JPH0348419A - Method and system for controlling production of thin film and method and system for exposure - Google Patents

Abstract

PURPOSE:To obtain an exposure method or the like for always stably holding a pattern size irrespective of an irregularity in various processes by radiating with a light of exposure wavelength having known illuminance, measuring timing variation in optical properties of a resist, and controlling exposure energy amount based on optimum exposure energy amount obtained from the measured result. CONSTITUTION:A region on a substrate of semiconductor or the like coating with a resist is previously radiated with a light having exposure wavelength of known illuminance, timing variation in optical properties of the resist is measured, optimum exposure energy amount is obtained based on the measured result, the exposure energy amount is controlled based on the optimum exposure energy amount to expose the substrate coated with the resist. For example, data measured by an optical property measuring system 107 is used, the data measured by an optical property measuring system 56 is corrected by a process control system 45, the optical properties of only a photoresist is extracted, and optimum exposure energy is set to form a pattern as required for the data. The exposure energy is fed back to a projection exposure unit 58 through an interface 57 for exposure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the production of semiconductors, etc., and particularly to a thin film production control method and method suitable for stabilizing the production or processing of semiconductor thin films, and an exposure method and its method. This is related to the method. [Prior Art] As semiconductors become more highly integrated, pattern dimensions become finer, element structures become three-dimensional, and manufacturing processes become more complex. For this reason, it is necessary to pay more attention than ever to stabilizing the manufacturing process conditions of the equipment used in each manufacturing process. For example, when a projection exposure device transfers and exposes a pattern on a reticle onto a wafer, exposure light of a single wavelength with a relatively narrow wavelength band width is used, so it is necessary to When the photoresist film 74 exists, the exposure light 71 undergoes multiple reflections within the photoresist film 74 as shown in FIG. For this reason, there is a difference in exposure energy in the depth direction, and when viewed in an IR image, the cross section of the photoresist becomes uneven in the depth direction, as shown in FIG. 2(b). Also,
If there are variations in process conditions in various manufacturing equipment, the photoresist film thickness t and the formation state of the light-transmitting underlayer 74 will change, and as shown in Figure 3, when the photoresist is exposed with the same exposure energy, the lower The pattern dimensions change as the radius W of the photo resist in contact with the top layer of the stratum 73 changes. Therefore, in order to stabilize this pattern dimension W,
It is necessary to set the optimum light energy corresponding to the variation in the photoresist film thickness t and the formation state of the underlayer 74. Furthermore, if the optical properties and film thickness of the photoresist change due to changes in the coating and baking conditions of the photoresist coating equipment, the pattern dimensions will change even if the shape or state of the wafer underlying layer and the exposure and development conditions are the same. Therefore, even with this photoresist coating equipment, it is necessary to constantly monitor variations in coating and baking conditions, which are factors that cause variations in photoresist film thickness and optical properties, and to control them to keep them constant. On the other hand, in some thin film production/processing processes such as film and etching before and after the exposure process shown in FIG.
The thickness and optical properties of the processed thin film change due to slight variations in manufacturing process conditions. Therefore, in thin film production and processing equipment, it is necessary to constantly monitor the thickness and optical properties of the thin films being produced and processed, and to control the manufacturing process conditions to keep them constant. As described above, while there are variations in the manufacturing process conditions in the equipment used in each manufacturing process, for example, in the exposure process, as a way to keep the pattern dimensions constant, conventionally, one or several wafers were exposed on a trial basis. , @ image, measure the pattern dimensions with a measuring device, determine whether the exposure energy is good or bad based on the results, and provide feedback to the shutter opening/closing time of the illumination optical system, etc. in a so-called advance work. However, in the production of high-mix, low-volume products such as ASICs, it is necessary to perform this preliminary work every time a product is replaced, which increases the number of operations and becomes the main cause of a decline in the operating rate of exposure equipment. Additionally, as the level of integration increases, it is no longer possible to obtain sufficient accuracy with this method of correcting process condition fluctuations through preliminary work. Therefore, in order to eliminate this preliminary work,
As described in Publication No. 31116, assuming that the relationship between photoresist film thickness and pattern dimensions and the relationship between exposure energy and pattern dimensions are known, photoresist film thickness measurement is performed using a reduction projection theater optical device. A method was devised in which a device was installed to measure the photoresist film thickness on the wafer to be exposed, and the results were reflected in the exposure energy, thereby reducing variations in pattern dimensions and stabilizing them. In addition, in the thin film production/processing process, the thickness of the film produced and processed by the thin film production/processing equipment on the preceding wafer was measured, and the manufacturing process conditions were set based on this value. [Problem to be solved by the invention] Among the above conventional techniques, regarding pattern dimension stabilization,
By measuring the variation in the thickness of the applied photoresist film,
This is done by determining the optimal exposure energy and controlling the pattern dimensions. However, with the increasing integration of semiconductors, variations in the shape and state of the underlying layer due to variations in the formation and processing conditions during the thin film production and processing process, as well as variations in the coating and baking conditions during the photoresist coating process, have caused variations in the optical properties of photoresists. The influence of variations in manufacturing process conditions, such as variations in manufacturing process conditions, can no longer be ignored. In addition, in the thin film production and processing process of the above-mentioned conventional technology, the current film thickness measurement equipment is affected by variations in the shape of the underlying layer created in the previous process, resulting in errors in the film thickness measurement value. As a result, it has become difficult to accurately set optimal manufacturing process conditions from this film thickness measurement value. It is an object of the present invention to provide a thin film production control method and method for reducing variations in these various manufacturing process condition settings and constantly maintaining stable thin film production and processing. Another object of the present invention is to provide an exposure method and system that can always keep pattern dimensions stable despite these various process variations. [Means for solving the problem] The above purpose is to measure the optical properties of the underlying layer before forming and processing the desired thin film layer, and to measure the optical properties during or after the formation and processing of the thin film layer. This is achieved by accurately controlling manufacturing process conditions by adding corrections to fixed values. In other words, taking as an example the exposure process in which a pattern is transferred and exposed to photoresist, which is a thin film with light transmittance whose complex refractive index changes among the optical properties during thin film production and processing, in order to obtain the required pattern dimensions, Optimal exposure energy
This is achieved by determining the changes in the optical properties of the photoresist from the optical properties of the underlayer before coating the photoresist and the changes in optical properties due to exposure of the wafer after the photoresist is coated. As the photoresist is exposed to light, Figure 5(a)
, as shown in (b), the optical absorption coefficient (κ) and refractive index (n)
The optical properties such as The manner in which this characteristic changes over time differs due to changes in the reflectance of the underlayer due to changes in the manufacturing process conditions of the manufacturing equipment in the process before the exposure process, but when the transfer exposure to the wafer is completed, the photo The optical properties of the resist, such as its light absorption coefficient and refractive index, are almost constant. In Fig. 5, the optimum exposure end time varies as Tl, T2, and T3 due to the influence of manufacturing process condition variations, but W
The light absorption coefficient κl and the refractive index n1 in the light termination state are approximately constant. Therefore, we focused on this point and pre-exposed a part of the wafer coated with photoresist prior to the pattern exposure process to determine the light absorption coefficient (κ) and refractive index (n) of the photoresist.
) and other optical properties over time during the preliminary exposure process. However, since these values cannot be measured directly, the complex refraction of the photoresist is calculated from the change in the overall reflectance R of the wafer after the photoresist is applied, based on the measurement results of the optical properties of the underlying layer before the photoresist is applied. It is obtained by correcting and converting the ratio N (N=n-i・κ). Then, based on this, the exposure energy T, photoresist coating conditions, or photoresist baking conditions necessary for the photoresist on the wafer to meet the required pattern dimensional accuracy are determined, and the projection exposure apparatus that performs the actual pattern transfer is determined. This can be fed back to the illumination system or photoresist coating equipment, etc. to stabilize pattern dimension control. Similarly, we measured the temporal change in the spectral transmission spectrum of the base layer before photoresist application and the spectral transmission spectrum due to exposure of the wafer after photoresist application, and from these results, we determined the temporal change in the spectral transmission spectrum of the photoresist. There is also a method of calculating the exposure energy T, photoresist coating conditions, or photoresist baking conditions necessary for the photoresist on the wafer to satisfy the required pattern dimensional accuracy. Alternatively, taking as an example a thin film forming process in which a thin film with light transmission properties is formed, the optimum film forming conditions to obtain a desired film thickness can be determined based on the optical properties of the underlying layer before film formation and the film forming process. This is achieved by determining the changes in the optical properties of the film being coated from the changes in the optical properties of the wafer in the film. When a film is deposited on a wafer, the reflectance Rd from the wafer changes as the film is deposited, as shown in FIG. The appearance of this change in reflectance over time differs due to variations in the manufacturing process conditions of the manufacturing equipment in the process before a certain film process, so if the film deposition time is controlled from the reflectance change of the wafer, this time will become To
, TI. Here, when the optical characteristics of the underlying layer before being deposited are measured, the reflectance Rd from the wafer and the deposited film thickness d are measured.
The relationship is as shown in Figure 7, and if the change in reflectance of the wafer during film formation is converted to change in film thickness, the relationship between the reflectance from the wafer and the film formation time in Figure 6 is as follows: It can be replaced by the relationship between film thickness and certain film time. Therefore, using this relationship, the film thickness during film formation can be determined in real time.
Therefore, by converting the film deposition speed and film thickness obtained from this into the amount of process condition variation of the film deposition equipment and controlling it, it is possible to stabilize a certain film deposition equipment. In this way, the manufacturing process conditions can be accurately controlled by measuring the optical properties in advance before producing and processing the desired thin film layer, and by making corrections to the measured optical properties during or after the production and processing. This allows for stabilization. (Operation) The optical properties of the thin film in the thin film generation/processing process will be explained using reflectance as an example. This is done by measuring the total reflectance R at the same position on the wafer that was measured before forming and processing the thin film, or after forming and processing the thin film. Based on the complex refractive index n' of the upper layer, the optical properties of the thin film (thin film thickness d, absorption By analyzing changes in the coefficient κ and refractive index n), changes in the optical properties of thin films due to thin film formation and processing can be determined, and from this the amount of variation in process conditions can be determined accurately. "Wave Optics" (written by Hiroshi Kubota, Iwanami) According to the bookstore),
The total reflectance R from a thin film with optical transparency is R=f (N, n', R' I2t d)
N: Complex refractive index of the thin film to be produced/processed N=n−i・
κ n: Refractive index of the thin film produced/processed κ: Absorption coefficient n″ of the thin film produced/processed
Complex refractive index R' of the top layer of the thin film base layer to be processed: Reflectance of the thin film base layer to be generated/processed ■2: Irradiation illuminance d: Given by the thickness of the thin film to be generated/processed, n' I2 is determined in advance. If you measure it,
By measuring R' before forming and processing the thin film and correcting the measured value of the temporal change in the total reflectance R, it is possible to accurately determine the temporal change in the optical properties of the thin film being formed and processed. For example, when photoresist is irradiated with exposure light, the film thickness does not change before and after exposure, so from equation (1), n'
I2. If d is measured in advance, the complex refractive index N (N==n−
i・κ) can be accurately determined over time even if the reflectance of the underlayer changes due to variations in manufacturing process conditions. Therefore, in order to obtain the required pattern size, if we find the exposure energy E1 = I2 (illuminance) x T2 (time) that makes the complex refractive index of the photoresist N1 = nl-i・κ1, we get:
That energy is the optimal exposure energy. Furthermore, as shown in FIGS. 5(a) and 5(b), the optical characteristics of the photoresist eventually converge to a constant value κω,noo, which is a known value. Therefore, the relationship of equation (1) (where Noo = n
oo − i・κω is known. ), if we measure the reflectance R with respect to the change in the resist film thickness d in this state, we can determine the resist film thickness d from the reflectance using the relationship shown in Figure 15, as previously measured. The reflectance of the underlayer can be accurately determined even if it changes due to variations in manufacturing process conditions. Furthermore, the spectral transmission spectrum of a photoresist before and after exposure generally has characteristics as shown in Figure 16, but this curve changes when the reflectance of the underlying layer changes due to variations in manufacturing process conditions. Therefore, by measuring the spectral transmission spectrum of the underlayer before applying the photoresist and correcting the measured value of the spectral transmission spectrum during the exposure process, the temporal change in the spectral transmission spectrum with respect to the photoresist can be determined, and the spectral transmission spectrum at the end of exposure is calculated. The reference pattern data of the measured spectral transmission spectrum at the end of exposure is compared with the reference pattern data of -1.
By measuring the time until 3, the optimum exposure energy E(
I (illuminance) × T (time)) can be accurately determined. Then, by feeding back the optimal exposure energy determined here to the shutter opening/closing circuit of the exposure illumination system of the projection exposure apparatus, the reflectance of the underlayer is adjusted to reflect variations due to manufacturing process conditions when starting the actual exposure and transferring the pattern. It is possible to accurately and stably control pattern dimensions even if they change. In addition, it is known that the photoresist film thickness and initial light absorption coefficient vary from wafer to wafer or lot to lot due to instability of process conditions in the photoresist coating process. By partially exposing the photoresist on the wafer's scribe line, etc. using the above method, the measured value of the change in optical properties is corrected, and if this result is fed back to the spin step and bake step so that it is constant, the photoresist The coating process can be stabilized. This also makes it possible to further reduce variations in pattern dimensions due to variations in process conditions. On the other hand, if the thin film to be produced/processed is a thin film produced/processed by a film forming device, an etching device, or a thin film coating device other than photoresist, the complex refractive index N of the thin film will be
(N=ni・κ) does not change, so from equation (1),
If n'I2,N is measured in advance, the reflectance R'' of the wafer before thin film formation and processing can be measured, and the measured value of the temporal change in the total reflectance R during formation and processing can be corrected.
It is possible to determine the temporal change in the film thickness d of the treated thin film.
Therefore, if the manufacturing process conditions of the generation/processing equipment are feedback-controlled so that the film thickness determined here is constant, the reflectance of the wafer before the thin film is generated/processed will change due to variations in the manufacturing process conditions. can also stabilize the generation and processing equipment. Transmittance, polarization characteristics, etc. are also available as methods for measuring the above-mentioned optical properties, and even if these are used, by performing the same correction as reflectance, it is possible to accurately determine fluctuations in manufacturing process conditions and stabilize the production/processing equipment. Can be done. [Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a thin film production control system according to a first embodiment of the present invention. In this figure, a wafer transport path 104
The optical properties of the wafer transferred to the optical property measurement system 108 are measured before the thin film is formed or processed. This measurement result is sent to the process control system 45 via the interface 103. The wafer whose optical characteristics have been measured by the optical measurement measurement system 108 is sent to the thin film production/processing device 107 via the wafer transport path 104, where a thin film is produced and processed. The wafer on which a thin film has been generated and processed in the thin film generation/processing device 107 is sent to the optical property measuring system 56 via the wafer transport path 104, and the optical property is measured at the same position where the optical property was measured in the optical property measuring system 108. It is measured. This result is sent to the process control system 45 via the interface 101 and corrected using the data sent from the optical property measurement system 108. The amount of process variation in the thin film production/processing equipment is calculated from this corrected data. The amount of process variation is fed back to the thin film production/processing device 107 via the interface 102, and the thin film production/processing device is stabilized by controlling the process conditions of the thin film production/processing conditions. In this embodiment, the optical property measurement system 108 and the optical property measurement system 56 can also be connected to a plurality of thin film production/processing devices to stabilize the thin film production/processing conditions. When the thin film generation/processing device of this embodiment is applied to a photoresist coating device, the thin film generation/processing device 107 applies the process fluctuation amount calculated by the process control system 45 to the photoresist coating/baking condition. It should be the amount of variation. In addition, when applying this embodiment to a thin film deposition apparatus as the thin film production/processing apparatus, the thin film production/processing apparatus 1i107 may be used as the thin film production apparatus. In addition, when applying this embodiment to an etching device as the thin film production/processing device, the thin film production/processing device 10
7 should be an etching device. In addition, when the thin film production/processing device of this embodiment is applied to a thin film coating device that coats a thin film whose optical properties do not change even when irradiated with light,
The thin film generation/processing device 107 may be a thin film coating device. FIG. 8 shows an example in which the thin film production processing device is a photoresist coating device and the controlled device is a projection exposure device. Using the data measured by the optical property measuring system 108, the process control system 45 uses the data measured by the optical property measuring system 56.
The optical characteristics of the photoresist alone are extracted, and from this data the optimal exposure energy is set to create the desired pattern. This exposure energy is fed back to the projection exposure apparatus 58 via the interface 57, and when the wafer whose optical properties have been measured by the optical property measurement systems 108 and 56 is carried into the projection exposure apparatus 58, the wafer is exposed using the exposure energy. Therefore, the dimensions of the pattern created by the projection exposure device 58 are stabilized. Figure 9 shows an example in which the thin film/formation processing device is a photoresist coating device and the device to be controlled is a developing device. Using the data measured by the optical property measuring system 108, the data measured by the optical property measuring system 56 is corrected by the process control system 45, the optical properties of only the photoresist are extracted, and the requested pattern is extracted from this data. The optimal development conditions are set to create the . These development conditions are fed back to the development device 109 via the interface 110, and when a wafer whose optical properties have been measured by the optical property measurement systems 108 and 56 is loaded into the development device 109, the wafer is developed under the development conditions for this wafer. , the pattern dimensions created by the developing device 109 are stabilized.

FIG. 10 is a schematic diagram of a device having a practical form of an optical property measuring system 56 and an interface 57, which is a first embodiment of the present invention. In this figure, a light source 26 such as a mercury lamp
The illumination light is guided to an optical fiber or the like by a lens 81 and is split into two. Each of these branched lights passes through shutters 29 and 30 via lenses 82 and 83, and is filtered by an interference filter 27 that passes the exposure wavelength, and a sharp cut filter 28 that passes the light of the exposure wavelength and light of a wavelength that is not involved in the exposure. It is converted into light that is not involved in exposure and extracted, and is turned on and off by switching the shutters 28 and 30. The optical axes of the two lights are brought together again by the dichroic mirror 31. The light is then irradiated onto the wafer by a half mirror 85. Lens 84 is an objective lens.
The field stop 55 narrows and limits the irradiation area of the exposure wavelength light onto the wafer. Close the shutter 29,
When the shutter 30 is opened, the wafer is irradiated with light that is not involved in exposure, transmitted through the half mirror 85, and reflected by the dichroic mirror 86. By moving, the fo. It is possible to search for specific areas on the wafer without exposing the resist. Also, if you stop the stage, open the shutter 29 and close the shutter 30,
Exposure light can be irradiated to that location. On the other hand, data on the complex refractive index n' of the underlayer and the irradiation intensity IO and resist film thickness d detected from the light amount measurement system 35 (described later) are measured in advance and input into the optimum exposure amount detection system 37, and the data are reflected from the underlayer. The ratio R' is measured by the optical property measuring system 108 and input to the optimum exposure amount detecting system 37. Therefore, the optimum exposure amount detection system 37 detects the above-described (( 1) Calculate the temporal change in the complex refractive index N of the resist from the relationship of formula, and set the complex refractive index N of the resist to the desired value N [(=n
The optimum exposure energy E1 (=exposure time T2
2) can be obtained. In addition, the optical properties of the photoresist are shown in Figures 5(a) and (
As shown in b), it finally converges to a constant value κ●,n-, which is a known value. Therefore, based on the relationship of equation (1) (however, Nea = no + - i · κψ is known), the reflectance R - with respect to the change in resist film thickness d in this state is as shown in Figure 11. ．． Therefore, if the photoresist is exposed and the reflectance Rcs is measured when the optical properties converge to a certain value, the film thickness d of the resist can be determined in advance from the relationship shown in FIG. It is required without doing anything. Therefore, the film thickness d of the photoresist can be determined from the change in the overall reflectance R from the photoresist as described above without measuring the film thickness of the photoresist in advance. Therefore, when calculating the temporal change in the complex refractive index N of the resist in the optimum exposure amount detection system 37, the determined film thickness d of the photoresist may be used. The illuminance detector 34 is a photoelectric conversion element that measures the illuminance at the wafer position. Exposure level 111! When the illuminance detector 34 is moved to the position where the change in the total reflectance R from the photoresist is detected using the xy stage, the optical measurement system 35 determines the illuminance of the exposure light based on the signal obtained from the illuminance detector 34. (irradiation illuminance I2) can be measured. Therefore, the optimum exposure amount detection system 37 detects the complex refractive index n + of the base layer, the reflectance R' of the base layer, which has been previously measured and input.
Data on the irradiation intensity z and resist film thickness d detected from the light amount measurement system 35 and the optical property measuring device (photo sensor) 3
Based on the change in the total reflectance R from the photoresist measured from 3, the temporal change in the complex refractive index N of the resist is calculated from the relationship of equation (1) described above, and the complex refractive index N of this resist is The optimum exposure energy El (=exposure Time TIX irradiance I2
).

The optimal exposure energy E1 determined in this way is the projection exposure system I! The data is transferred to the lighting control system 38 of 58. Next, we will explain the operation using the above structure. First, a wafer 18 coated with photoresist is loaded into the apparatus. Then, the shutter 29 is closed, the shutter 30 is opened, and the wafer 18 is irradiated with light that is not involved in exposure, and the alignment detection system 32 uses the scribe line, which is a part of the wafer that does not affect a part of the wafer, such as a place where circuits are transferred, to the wafer. a part of
Move and search the wafer 18 on the Y stage 36. At this position, the area to be exposed is limited by the field stop 55, the shutter 30 is closed, the shutter 29 is opened, and the wafer l8 is exposed to light at the exposure wavelength. Then, an optical property measuring device (photo sensor) measures the change in the catfish reflectance R from the photoresist, which is a secondary optical property from the wafer during exposure.
33, and the optimum exposure amount detection system 37 calculates the complex refractive index n' of the base layer measured and inputted in advance, the reflectance R' of the base layer, the irradiance I2 detected from the light amount measurement system 35, and the resist film. Based on the data on the thickness d and the change in the total reflectance R from the photoresist measured by the optical property measuring device (photo sensor) 33, the complex refractive index N of the resist can be calculated over time from the relationship of equation (1) above. The change is calculated, and the complex refractive index N of this resist is set to the desired value Nl (=nl-i・κl)
, that is, the optimum exposure time T2 for exposing the wafer 18 is determined. Next, the illuminance detector 34 is moved to the exposure position on the XY stage 36, and the illuminance of the exposure light is detected by the illuminance detector 34 and determined by the light amount measuring system 35. In this way, the optimum exposure amount detection system 37 determines the optimum exposure energy E1 (=exposure time TAX irradiation intensity I2) based on the irradiation illuminance I2 obtained from the light amount measurement system 35 and the optimum exposure time T2, and calculates the optimum exposure energy E1 (=exposure time TAX irradiation illuminance I2) It is transferred to the lighting control system 38 of W58.
When the wafer 18 for which the optimum exposure energy El has been determined as described above is carried into the projection exposure apparatus 58, the exposure light illuminance detector (the first
Not shown in Figure 0. It is shown as 9 in Figure 16. ), the illumination control system 38 determines the exposure time T! corresponding to this energy based on the exposure light illuminance rt detected by the exposure light intensity rt. is set, and the shutter of the exposure illumination system 39 is activated. In this embodiment, the optical property measuring system 56 can also be connected via an interface 57 to a plurality of projection exposure apparatuses into which the wafer 18 for which the optimum exposure energy El has been determined is loaded.

In this embodiment, by using a spectrometer instead of the photosensor 33, it is also possible to measure the spectroscopic spectrum during the exposure process as a secondary optical characteristic. At this time, as in the previous embodiment, first, the shutter 29 is closed, the shutter 30 is opened, the wafer 18 is irradiated with light that does not involve exposure, and the alignment detection system 32 is used to irradiate a part of the wafer, for example, a part of the wafer where the circuit is to be transferred. The wafer 18 is moved on the XY stage 36 to find a part of the scribe line that does not affect the process. At this position, the field diaphragm 55 limits the area to be exposed, and with the shutter 30 open, the shutter 29 is further opened, and the wafer 18 is exposed to light containing many wavelengths and light of the exposure wavelength. Then, as shown in FIG. 12, the spectrometer detects the spectral transmittance that changes over time from the spectral transmittance before exposure to the spectral transmittance after exposure. Therefore, data on the spectral transmittance after exposure (reference spectral transmittance), which shows a constant value, is input to the optimum exposure amount detection system 37, and the optimum exposure amount detection system 37 detects the spectral transmittance detected by the spectrometer. Temporal change in transmittance and spectral transmittance after exposure (
and the reference spectral transmittance) data, and find the optimal exposure time T2 that matches. Next, the illuminance detector 34 is moved to the exposure position on the XY stage 36, and the illuminance of the exposure light is detected by the illuminance detector 34 and determined by the light amount measuring system 35. In this way, the optimum exposure amount detection system 37 determines the optimum exposure energy El (=exposure time TAX irradiation intensity I2) based on the irradiation illuminance I2 obtained from the light amount measurement system 35 and the optimum exposure time T2.
Find. It is transferred to the illumination control system 38 of the projection exposure system ii58. Therefore, similarly to the embodiment described above, the wafer 18 for which the optimum exposure energy El was determined as described above is transferred to the projection exposure apparatus 5.
8, the exposure light illuminance II detected by the exposure light illuminance detector (not shown in FIG. 10, shown as 9 in FIG. 16) installed in the projection exposure apparatus 58.
From this point, the illumination control system 38 sets an exposure time Tl corresponding to this energy, and the shutter of the exposure illumination system 39 is moved. Different examples of this embodiment are shown in FIGS. 13 and 14. The basic structure is based on Figures 13 and 14 or is the same as Figure 10. Figure 13 shows the influence of the underlayer by illuminating light of a wavelength that is not involved in exposure to measure secondary optical characteristics from an oblique direction, detecting it obliquely, and examining the polarization characteristics and reflectance at this time. Optical properties can be measured in a way that is less susceptible to damage. In addition, in FIG. 14, changes in the transmittance or spectral transmittance of the photoresist on the transparent substrate due to exposure are measured using photosensors 33 and 33'. It can be measured by This is effective when transferring and exposing a pattern to a material 90 that transmits light, such as a TPT liquid crystal display. Also, unlike the above embodiment, the device controlled by the optical property measuring system 56 is a photoresist coating device! ! The first example is 49.
Shown in 5. That is, data is sent from the process control system 45 to the interface 102 so that the measurement results of changes in optical properties measured by the optical property measuring system 56 are always constant, and based on this data, for example, the rotation speed of the spinner 41, the baking furnace etc. The photoresist coating process can be stabilized by controlling the temperature and baking time of 42 degrees. In this embodiment, the optical property measurement system 56 is connectable via an interface 57 to a plurality of photoresist coating devices for stabilizing the photoresist coating process. 40 indicates a wafer stocker. In addition, the projection exposure system can be used using the optical property measurement system 56! ! 58
It is also possible to control both the photoresist coating device 49 and the photoresist coating device 49.

Figure 16 shows an example in which a reduction projection exposure apparatus is equipped with a system for measuring changes in optical characteristics due to exposure of a wafer. In this figure, the illumination light from a mercury lamp 1 is controlled to have a constant illuminance by a power supply control system 2. On the other hand, the half mirror 3 branches the system into an exposure system and a real alignment system. The opening/closing time of the shutter 5 is controlled by the shutter control system 4 for the light transmitted through the half mirror 3. Note that in this system, only the exposure wavelength is extracted by the interference filter 59. The light transmitted through the condenser lens 6 is irradiated onto the reticle 7 that has formed the required pattern, and then is projected by the reduction projection lens 8.
A reticle image is formed on the wafer 18. On the other hand, the light reflected by the half mirror 3 is guided to the pre-alignment system via a field stop 55 using means such as an optical fiber 90. For the light guided through the Bria alignment system, the light that passes through the filter 12 or 13 is selected by switching between the sharp cut filter 12, which transmits only light with wavelengths that are not involved in exposure, and the interference filter 13, which corresponds to the exposure wavelength. ．． By selecting the sharp cut filter 12 as the filter, the alignment pattern on the wafer 18 is detected by the clear alignment detection system 32 without exposing the photoresist, and the light with the focused exposure wavelength is detected at the scribe line position on the wafer 18. It can be set to . Here again, by switching to the interference filter 13, the wafer 18 can be partially exposed, and the field diaphragm 55 can limit the area irradiated with the exposure light. The photosensor 33 measures the temporal change in the total reflectance R of the photoresist during the exposure process, and the optimum exposure amount detection system 37 detects the complex refractive index n' of the underlayer measured and inputted in advance, and the film thickness d of the resist. From the light amount measuring system 35 which inputs the reflectance R' of the base layer measured by the optical property measuring system 108, the total reflectance R of the photoresist measured by the photosensor 33, and the output of the illuminance detector 9. Based on the value of the detected illuminance I2, the temporal change in the complex refractive index N of the resist is calculated from the above equation (1), and the complex refractive index N of the resist is set to the desired value N, (=n, -i・κ The optimal exposure time T until , )
2 is calculated, and the optimum exposure energy E is calculated from the values of this optimum exposure time T2 and the illuminance I detected from the light amount measurement system 35.
1 is determined, and the exposure illuminance I2 is measured by the illuminance detector 9 when a circuit pattern is actually exposed on the reticle 7 using the reduction projection lens 8 for the wafer 18 for which the optimum exposure energy E is determined. Based on the exposure illuminance I obtained from 35, the optimum exposure energy E. In the same manner as in the above embodiment, the exposure illuminance or exposure time T1 is determined, and the light source voltage is controlled by the power supply control system 2 which is the illuminance control system via the interface 57, and the shutter opening/closing time is controlled by the shutter control system 4. ．． The illuminance detector 9 is a photoelectric conversion element that measures the illuminance at this imaging position, and the illuminance is measured by the light amount measuring system 35. Further, the illuminance detector 9 can also measure the illuminance in the Bria alignment system by moving the XY stage 36. In this embodiment, there is no need to measure absolute illuminance. ? An illuminance detector 9 measures the illuminance at the exposure position where the pattern drawn on the reticle 7 is transferred onto the wafer l8 in the exposure system.
The illuminance detector 9 is moved to the position where the Bria alignment was performed, and the illuminance of the light guided to the Bria alignment system is determined. Then, the optimum exposure time T. at the exposure position for transferring the pattern drawn on the reticle 7 onto the wafer 18 is determined. teeth,
If the illuminance at this exposure position is T2, the illuminance at the rear alignment position is T8, and the optimum exposure time for the light guided to the rear alignment system is T8, then it is determined by the following equation (2). Tyu=(L/I■)×T2 (2) As a result, the optimum exposure time T at the exposure position for transferring the pattern drawn on the reticle 7 onto the wafer 18 is the optimum exposure time. The optical properties (
(reflectance, spectroscopic spectrum, etc.) and the illuminance measured by the illuminance detector 9. In order to obtain the exposure time determined here, the control system 4 controls the illuminance of the mercury lamp by the power supply control 2 of the illumination system and the opening/closing time of the shutter 5, and the pattern drawn on the reticle 7 is transferred to the wafer 18 with the optimum exposure time. Transfer it on top. In this way, the pattern on the reticle 7 can be transferred and exposed in accordance with the required pattern.In addition, in this embodiment, the optimum exposure energy for the wafer immediately before exposure is obtained, and since the time from obtaining the optimum exposure energy to exposure is short, the process It is not affected by fluctuations. Next, FIG. 17 shows an example in which an optical property measuring system 56 is mounted on the photoresist coating device 49. In this figure, a wafer 18 has its underlayer optical properties measured by an optical property measuring system 108, and passes through a wafer tensioner 40, a spinner 41 for coating photoresist, and a baking oven 42.
Thereafter, the optical measurement system 56 measures changes in the reflectance of the photoresist during the exposure process. The results obtained from the optical property measuring system 56 and the results obtained from the optical property measuring system 108 are input to the process control system 45 via the interfaces 57 and 103, and the results are inputted to the process control system 45 via the interfaces 57 and 103, and the results are inputted to the process control system 45 via the interfaces 57 and 103, and (bake conditions etc. by the furnace 42) are controlled. This embodiment makes it possible to stabilize the photoresist coating process by reducing changes in the photoresist film thickness and optical properties such as absorption coefficient due to variations in process conditions during the photoresist coating process. As a result, uniform exposure can be performed on a stabilized wafer during the photoresist coating process. In addition, in the above example, the total reflectance R of the photoresist
Although the complex refractive index N of the photoresist is calculated from the above, it is clear that it is sufficient if the complex refractive index N of the photoresist can be directly measured. In Figure 18, the device that corrects process variations is a photoresist coating device! 49 and a reduction projection exposure device 58 to stabilize the photoresist coating, baking and exposure process. In this figure, the optical properties of the wafer carried into the exposure process are measured in an optical property measurement system 108 before photoresist is applied, and this data is sent to the process control system 45 via an interface 103. The wafer whose optical characteristics have been measured is transported to a photoresist coating device It49 via the wafer transport path 104, where it is coated with photoresist. It is baked. The wafer coated with this photoresist is carried into the optical property measuring system 56 via the wafer transport path 104, and its optical properties are measured by the optical property measuring system 108 before coating the photoresist, and this data is sent to the process via the interface 101. It is sent to the control system 45. The data sent from the optical property measurement system 108 is used to correct the data sent from the optical property measurement system 56, and based on the results, the process control system 45 determines the amount of process condition variation in the exposure process. The optimum exposure energy and the amount of process condition variation in the photoresist coating process are determined. When the wafer whose optical characteristics have been measured is carried into the projection exposure apparatus 58 via the wafer transport path 104, the optimum exposure energy corresponding to this wafer is transmitted from the process control system 45 to the projection exposure apparatus 5 via the interface 57.
The amount of process variation in the photoresist coating process determined by the process control system 45 is inputted to the interface 102 and exposed at the optimum exposure time commensurate with this energy to stabilize the pattern dimensions. This is fed back to the photoresist coating device 49, and the photoresist coating and baking conditions are stabilized. In this example, the optical property measuring system 108 and the optical property measuring system 56 are equipped with a plurality of photoresist coating devices that can stabilize the photoresist coating and baking conditions, which are the manufacturing process conditions, and the optimum exposure energy. It can also be connected to multiple projection exposure systems into which wafers are loaded. If the above exposure, coating, and baking condition controls are performed once every few wafers, it has the effect of automating conventional preliminary work. Also,
Process conditions vary from wafer to wafer even with the same manufacturing equipment, and if this needs to be taken into consideration, it is possible to control the exposure, coating, and baking conditions described above for each wafer. Furthermore, if variations in process conditions within a wafer become a problem, it is possible to control the exposure conditions and the coating and baking conditions within the wafer for each chip.

In the above embodiment, the optical property measuring system 108 can be built into the photoresist coating equipment 1i49, and the optical property measuring system 56
can be built into the photoresist coating device 49 or the projection exposure device 58, and the optical property measuring system 56 can be incorporated into the projection exposure device 58.
If built into the 8, it becomes a projection exposure system! The optimum exposure energy for the wafer can be set just before the pattern is transferred and exposed in step 58.
Since the time from finding the optimal exposure energy to exposure is short, it is not affected by process variations due to the time from photoresist application to exposure. Additionally, since the wafer transport path is short, this has the advantage of improving the efficiency of this process and reducing the adhesion of foreign matter during transport. Furthermore, in the above embodiment, if the optical property measuring system 56 is built into the photoresist coating device 49, it is possible to measure the optical properties of the photoresist immediately after coating and baking. ! 49 process variations can be controlled in real time, making it possible to create stable wafers. [Effects of the Invention] As explained above, according to the present invention, in the process of producing and processing a thin film having optical transparency, the optical characteristics of the wafer before being produced and processed are measured, and the optical properties of the wafer are measured after being produced and processed. By extracting data only for the thin film produced/processed by adding corrections to the measured values of the optical properties of The processing equipment can be stabilized.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the schematic structure of a thin film production control system according to the first embodiment of the present invention, and Fig. 2 shows the effects of multiple reflections within the photoresist and the underlying layer type or film having light transparency. Figure 3 is a diagram showing the standing wave effect, Figure 4 is a diagram showing the flow of the exposure process, Figure 5 is a diagram showing the relationship between exposure energy and the reflectance and refractive index of photoresist, and Figure 3 is a diagram showing the standing wave effect. 6 is a diagram showing the relationship between a certain film time and the reflectance, FIG. 7 is a diagram showing the relationship between the film thickness d and the reflectance Rd, and FIG. 8 is a diagram showing the relationship between the film thickness d and the reflectance Rd.・A block diagram showing a schematic configuration of a system in which the processing device is a photoresist coating device and the controlled device is a projection exposure device. FIG. FIG. 10 is a block diagram showing a schematic configuration of a system in which the device controlled by the resist coating device is a developing device, and FIG. 10 is a block diagram showing a system showing a practical form of the optical property measuring system of the first embodiment of the present invention. , Figure 1l is a diagram showing the relationship between the reflectance R of the photoresist and the change in the film thickness d of the photoresist, Figure 12 is a diagram showing the spectral spectrum of the photoresist before and after exposure, and Figure 13 is a diagram showing the practical use of optical properties. Fig. 14 is a configuration diagram of a system that illuminates from an oblique direction and detects obliquely, which is a modification of the embodiment of the optical characteristics. FIG. 15 is a system configuration diagram when the process to be controlled is a photoresist coating process in an embodiment of the present invention, and FIG. 16 is a diagram showing the optical characteristic measurement of an embodiment of the present invention. FIG. 17 is a diagram showing a system configuration in which an optical property measuring system is installed in a photoresist coating apparatus according to an embodiment of the present invention, and FIG. 18 is a diagram showing an embodiment of a projection exposure apparatus according to the present invention. FIG. 2 is a diagram showing a system configuration having a function of controlling the photoresist coating process and the exposure amount in a modified example of FIG. 18... Wafer, 26... Light source, 27... Interference filter 28... Sharp cut filter 29.30... Shutter, 31... Dichroic mirror 32... Alignment detection system (TV camera) 3
3... Optical property measuring device (photosensor) 35... Light amount measurement system, 37... Optimal exposure amount detection system 38... Illumination control system, 45... Process control system 49... Photoresist Coating device 56, 108... Optical property measuring system 57, 101, 102, 103... Interface 58... Projection exposure device, 104... Wafer transport path 107... Thin film production, processing device

Claims (1)

[Claims] 1. A region on a substrate such as a semiconductor coated with a resist is irradiated with light of an exposure wavelength whose illuminance is known in advance to measure temporal changes in the optical properties of the resist, and based on the measurement results. An exposure method characterized by determining an optimum amount of exposure energy based on the optimum amount of exposure energy, controlling the amount of exposure energy based on the optimum amount of exposure energy, and exposing a substrate coated with a resist. 2. Measure the temporal changes in the optical properties of the resist by irradiating the area on the substrate, such as a semiconductor, coated with a resist, with light of an exposure wavelength whose illuminance is known in advance. Based on the measurement results, determine the optimal resist An exposure method characterized by determining coating or baking conditions, controlling coating or baking conditions for a resist on a substrate based on the optimum coating or baking conditions, and exposing the controlled substrate. 3. The temporal change in the exposure characteristic of the resist is measured by the reflectance of light, the refractive index of light, the transmittance of light, the polarization property, or the absorption coefficient of light from the resist. The exposure method according to claim 1 or 2. 4. The exposure method according to claim 1 or 2, characterized in that temporal changes in optical characteristics are measured using light having an exposure wavelength and at least one type of light different from the exposure wavelength. 5. The exposure method according to claim 1 or 2, characterized in that the film thickness of the resist is measured from changes in optical properties of the resist before and after exposure. 6. Measuring means for measuring temporal changes in the optical properties of the resist by irradiating a region on a substrate such as a semiconductor coated with a resist with light of an exposure wavelength whose illuminance is known in advance; Optimal exposure energy amount calculation means for determining the optimum exposure energy amount based on temporal changes in optical properties of the resist, and control for controlling the exposure energy amount based on the optimum exposure energy amount calculated by the optimum exposure energy amount calculation means. 1. An exposure method comprising: a control means; and an exposure means for controlling an amount of exposure energy by the control means and exposing a substrate coated with a resist. 7. The exposure method according to claim 6, wherein the control means includes means for controlling opening and closing of a shutter of the illumination optical system. 8. Measuring means for measuring temporal changes in the optical properties of the resist by irradiating a region on a substrate such as a semiconductor coated with resist with light of an exposure wavelength whose illuminance is known in advance, and Optimal coating or baking condition calculation means for determining the optimum coating or baking conditions for the resist based on temporal changes in the optical properties of the resist; and the optimum coating or baking conditions calculated by the optimum coating or baking condition calculation means. 1. An exposure method comprising: a control means for controlling coating or baking conditions for resist on a substrate based on the above; and an exposure means for exposing the substrate controlled by the control means. 9. The exposure method according to claim 8, wherein the control means is a resist coating device. 10. Claim characterized in that the measuring means is configured to measure by the reflectance of light from the resist, the refractive index of light, the transmittance of light, the polarization property, or the absorption coefficient of light. 6 or 8. The exposure method described in 6 or 8. 11. The measuring means according to claim 6 or 8, wherein the measuring means is configured to measure temporal changes in optical properties using light at an exposure wavelength and at least one type of light different from the exposure wavelength. Exposure method. 12. The exposure method according to claim 6 or 8, wherein the measuring means measures the film thickness of the resist based on changes in optical properties of the resist before and after exposure. 13. Before producing or processing a thin film having light transmission properties on a substrate such as a semiconductor, the first optical property of this substrate is measured, and during or after producing or processing the thin film on the substrate. , of the thin film produced or processed or produced or processed by measuring a second optical property of the substrate and correcting the measured second optical property based on the measured first optical property. A thin film production control method characterized by accurately determining optical properties and controlling conditions of a thin film production or processing device based on the determined optical properties of the thin film to produce or process a thin film on a substrate. 14. The thin film production control method according to claim 13, wherein the thin film is a resist, and the conditions to be controlled are an amount of exposure energy, resist coating or baking conditions, or development conditions. 15. The thin film production control method according to claim 13, wherein the thin film is a base thin film, and the conditions to be controlled are thin film forming conditions, thin film etching conditions, or thin film coating conditions. 16. Measuring the first and second optical properties above based on light reflectance, light refractive index, light transmittance, polarization property, spectral transmission spectrum, or light absorption coefficient. 14. The thin film production control method according to claim 13. 17. The thin film production control method according to claim 13, wherein the first and second optical characteristics are measured based on temporal changes. 18. The thin film production control method according to claim 13, wherein the first and second optical characteristics are measured using light at an exposure wavelength and at least one type of light different from the exposure wavelength. 19. The thin film production control method according to claim 13, wherein the first and second optical properties are measured based on changes in the optical properties of the resist before and after formation and processing with respect to the film thickness of the thin film. 20. The optical characteristics of the underlying layer are measured by irradiating light of an exposure wavelength whose illuminance is known in advance to a region on a semiconductor or other substrate before photoresist is applied to the semiconductor or other substrate coated with photoresist. The upper region is irradiated with light of an exposure wavelength whose illuminance is known in advance, and the temporal changes in the optical properties of this photoresist are measured. Based on these measurement results, the optimum amount of exposure energy is determined. An exposure method characterized by controlling the amount of light and exposing a pattern drawn on a photomask onto a substrate coated with photoresist. 21. The optical characteristics of the underlying layer are measured by irradiating a region on a substrate such as a semiconductor with photoresist coated with light of an exposure wavelength whose illuminance is known in advance. The above area is irradiated with light of an exposure wavelength whose illuminance is known in advance, and the temporal changes in the optical properties of this photoresist are measured, and the optimal coating or baking conditions for the photoresist are determined based on these measurement results. , controlling the coating or baking conditions of the photoresist on the substrate based on the optimal coating or baking conditions, and exposing the controlled substrate with a pattern drawn on the photomask. Method. 22. A measuring means for measuring the optical properties of a substrate such as a semiconductor on which a thin film having light transmission properties is produced or processed, and a method for accurately measuring the optical properties of the thin film produced or processed based on the optical properties measured by the measuring means. The calculation means to obtain,
a control means for controlling the conditions of a thin film production or processing device based on the characteristics of the thin film determined by the calculation means; and a control means for controlling the production or processing conditions by the control means to produce a thin film on a substrate or to produce a thin film on a substrate. 1. A thin film production control method characterized by comprising a thin film production or processing means for processing. 23. Irradiate the area on the substrate such as a semiconductor before applying the resist with light of an exposure wavelength whose illuminance is known in advance to determine the optical characteristics of the underlayer and the area on the substrate such as the semiconductor to which the resist is applied. A measuring means for measuring temporal changes in the optical properties of the resist by irradiating light with an exposure wavelength of known illumination intensity, and temporal changes in the optical properties of the underlayer and the optical properties of the resist measured by the measuring means. an optimum exposure energy calculation means for calculating an optimum exposure energy amount based on the optimum exposure energy amount; and a control means for controlling the exposure energy amount based on the optimum exposure energy amount calculated by the optimum exposure energy amount calculation means; An exposure method characterized by comprising an exposure means for controlling the amount of exposure energy to expose a pattern drawn on a photomask onto a substrate coated with a photoresist. 24. The exposure method according to claim 23, wherein the control means includes means for controlling opening and closing of a shutter of the illumination optical system. 25. Irradiate the area on the substrate such as a semiconductor before applying the resist with light of an exposure wavelength whose illuminance is known in advance to determine the optical characteristics of the underlayer and the area on the substrate such as the semiconductor to which the resist is applied. A measuring means for measuring temporal changes in the optical properties of the resist by irradiating light with an exposure wavelength of known illumination intensity, and a temporal change in the optical properties of the underlayer and the optical properties of the photoresist measured by the measuring means. a means for calculating optimal coating or baking conditions for a photoresist based on changes in conditions; and conditions for coating or baking a photoresist on a substrate based on the optimal coating or baking conditions calculated by the optimal coating or baking condition calculating means. 1. An exposure method comprising: a control means for controlling the control means; and an exposure means for exposing a pattern drawn on a photomask onto a substrate controlled by the control means.