JPS606852A - Monitoring method of plasma and monitor - Google Patents

Abstract

PURPOSE:To obtain the density or rate distribution of a specific chemical species in plasma by selecting sequentially measurement positions of the plasma and separating plasma light from each measurement position. CONSTITUTION:A monitor collect plasma light 2 at measurement positions in a working device 1, and a spectral means 4 extracts all of the plasma light 2 and plasma light 2a of specific wavelength emitted by the specific chemical species in the plasma light 2 alternately. The spectral means 4 is formed by fixing the discoid filter 43 consisting of a filter part 41 passing the light of the specific wavelength and plural kinds of dimming filter parts 42 having no wavelength selectivity and the discoid mask 46 consisting of a light transmission part 44 and a light shield part 45 to the rotating shaft 48 of a motor. The phases of the filter 43 and mask 46 are so set that the detection output ratio of the plasma light 2 and plasma light 2a is a proper value. A light collecting means 3 is moved to an optional position in a window 14 through a scanning mechanism.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is directed to processing processes that utilize plasma, such as sputtering and dry etching, to improve the chemistry of specific molecules, atoms, ions, etc. contained in plasma. Regarding plasma monitoring methods and monitors that determine the distribution of species concentration, in the manufacturing process of LSI and VLSI, fine circuit patterns with line widths of several μm or less or 1 μm or less can be arranged at high density. requested.

For this reason, a shift is being made from wet processes such as plating and etching using chemical liquids to dry processes such as dry etching and sputtering that enable fine processing.

In order to accurately perform fine machining using a dry process, it is necessary to minimize fluctuations in machining conditions and to monitor the progress of machining. For this reason, several monitors have been proposed that monitor the machining status by utilizing the light emission of plasma generated during machining in a dry process.

For example, in dry etching monitoring, the amount of light emitted by the entire plasma generated during processing and the amount of light emitted by the etching substance contained in the plasma are measured using separate measuring means, and the results are compared. The end point of etching is detected by measuring the concentration of the etching substance contained in the plasma.ΦAlso, in sputtering monitoring, two types of chemical species are detected from among the chemical species that make up the plasma generated during processing. By measuring the amount of light emitted by each using separate measurement means and comparing the results, the sputtering rate and the composition of the film to be formed can be predicted.

These monitors measure the luminescence of the entire target plasma (or a part of it), so
or a part of it).

For this reason, it is not possible to grasp variations in the machining conditions within the machining area. For example, in the case of dry etching, excessive or insufficient etching occurs, and in the case of sputtering, it is impossible to prevent variations in the thickness and composition of the formed film. Furthermore, it is not possible to obtain information necessary to maintain the uniformity of processing within the same lot or the reproducibility of processing conditions between lots.

Furthermore, since two detection means are used, the apparatus becomes expensive and large. Furthermore, it has many drawbacks, such as errors occurring due to differences in sensitivity of each detection means and differences in amount of light received due to differences in placement positions.

[Purpose of the invention]

An object of the present invention is to provide a plasma monitoring method and monitor for measuring the concentration of a specific chemical species in plasma or the distribution of the ratio of two specific chemical species.

[Summary of the invention]

In order to achieve the above object, in the present invention, plasma measurement positions are sequentially selected, and plasma light from each measurement position is combined with plasma light emitted by all chemical species constituting the plasma and plasma light contained therein. By detecting the plasma light emitted by a specific chemical species contained in the plasma light, or by detecting the plasma light emitted by two specific chemical species contained in the plasma light, and comparing the detection results, Concentration of specific chemical species at each of those measurement positions or 2
It is characterized by determining the concentration or ratio distribution of specific chemical species in plasma by measuring the ratio of specific chemical species.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a monitor that monitors the plasma generated in the processing device 1 is a lighting means 3 that faces the window 14 of the processing device 1, and that collects plasma light 2 at a measurement position, guides it to a predetermined position, and radiates it. and a spectroscopic means that receives the plasma light 2 emitted from the lighting means 3 and alternately extracts all of the plasma light 2 and plasma light 2a of a specific wavelength caused by the emission of specific chemical species contained in the plasma light 2. 4, a light detection means 5 for converting the plasma light 2, 2a extracted by the spectroscopic means 4 into an electric signal 21, 21a according to its intensity, and a control means for instructing the light collecting means 6 to a measurement position. 6 and the electric signal 21.21a connected to the photodetection means 5 and the control means 6 and applied from the photodetection means 5 to calculate the concentration of the specific chemical species in the plasma at the measurement position, A measuring means 7 that makes the concentration correspond to a signal at a measuring position applied from the control means 6, a measuring position connected to this measuring means 7 and applied from the measuring means 7, and a concentration of a specific chemical species at the measuring position. a display means 8 such as a display for displaying information; and the measuring means 7.
The recording device 9 is connected to the measurement means 7 and records information on the measurement position where the voltage is applied from the measurement means 7 and the concentration of the specific chemical species at the measurement position.

Note that only one of the display means 8 and the recorder 9 may be used.

The processing device 1 includes a pair of upper and lower electrodes 1 in an airtight container 11.
2.13, and a window 14 on the side wall for monitoring the interior.
is formed. Then, by placing a workpiece on the electrode 15 and applying a voltage between the electrodes 12 and 13, plasma is generated between the workpiece and the electrode 12, and this plasma emits light.

The lighting means 6, as shown in FIGS. 2 and 6,
It is composed of a lighting optical system 31 and a scanning mechanism 310.

The lighting optical system 61 includes an optical fiber 62, a collimator 33 fitted onto one end of the optical fiber 32, and lenses 3456 and 57 supported within the collimator 53.
A partition plate 59 is supported between the lenses 56 and 57 so that the pinhole 58 is located at the focal point of the lens 3637.

The other end of the optical fiber 62 is connected to the spectroscopic means 4. Further, the lens 64 has a focal length that is large enough to reach the inner wall of the processing device 1 on the opposite side from the window 14 .

The scanning mechanism 310 is supported by a pace 311 attached to the processing device 1. Four guide plates 312 are installed on the pace 311, and a ceiling plate 3 is attached to the upper end of the guide plate 312.
16 is fixed. Further, a first feed screw 314 is disposed between the pace 511 and the top plate 515.
12 and is rotatably supported, and the ceiling plate 313
It is rotated in forward and reverse directions by a motor 315 supported above. Print on the guide pa 312! A first movable base 616 is formed with a hole that can be freely fitted into the feed screw 314 and a screw hole that is screwed into the feed screw 314, and is disposed between the pace 611 and the top plate 313. As a result, it moves along the guide path 612. A pair of guide pavers 518 are fixedly supported on the movable table 316 by a pair of brackets 617. A second feed screw 319 is inserted between the brackets 317 and a guide pawl 618.
The motor 320 is supported rotatably in parallel with and is rotated in forward and reverse directions by a motor 320 supported on a moving table 316. A bearing 321 that is slidably placed on the guide pawl 318 and a nut 322 that is screwed onto the feed screw 619.
A second moving table 325 is fixed to the feed screw port 1.
It is designed to move in the horizontal direction by rotation of 9. Note that the moving table 523 is formed sufficiently long in the direction perpendicular to the window 14 of the processing apparatus 1. The moving table 62
A pair of guide pads 625 are fixedly supported on a pair of platen plates 324 (one of which is not shown) between the brackets 324.
A feed screw 326 is rotatably supported in parallel with the guide pawl 325, and a motor (
(not shown) rotates in forward and reverse directions. A sixth moving table 329 is fixed to a bearing 527 that is slidably fitted to the guide pad 325 and a nut 328 that is screwed to the feed screw 526. It is designed to move vertically.

The optical fiber 32 of the lighting optical system 31 and the collimator are connected to the moving table 529 via a platen 530.
A lens filter 4 is supported so as to face the window 14.

With such a configuration, the collimator 3 of the lighting optical system 31 can be adjusted by rotating the feed screw 314°619.
5 can be moved to any position within a plane parallel to the window 14 of the processing device 1. Furthermore, by rotating the feed screw 326, the collimator 33 can be moved to any position in the direction Ia perpendicular to the window 14.

Therefore, the focal point 55 of the lens 64 can be moved to any position within the vertically extended range of the window 14 in the processing device 1. Then, the lens 34 projects the plasma light 2 from the focal point 35 position of the incident plasma light 2 and the plasma light 2 passing through the same locus as the plasma light 2 into a lens 56vM as parallel light. . lens 3
6 condenses this parallel light 2 and focuses it 9 on the pinhole 38 of the partition plate 59 as an image at the focal point 35 of the lens 34 .

Then, the plasma light 27/- transmitted through the pinhole 38
The lens 37 converts the light into parallel light again and projects it onto the optical fiber 32.

At this time, other than the plasma light 2 that emits light at the focal point 65 of the lens 64 and the plasma light 2 that follows the same trajectory 311 as this plasma light 2, it enters the lens filter 4. plasma light 2
does not become parallel light even if it passes through the L/lens 34, so
When the light is focused by the lens filter 6, it is reflected around the outer periphery of the pinhole filter 8 and cannot pass through the pinhole 67. Therefore, the two plasma lights transmitted through the pinhole 37 and the plasma light 2 at the focal point 35 of the lens 64,
Other plasma light 2 passing along the same trajectory as this plasma light 2
By regarding this as the plasma light 2 from the focal point 65 of the lens 34, it becomes possible to measure the plasma three-dimensionally.

The spectroscopic means 4 includes a filter section 41 that passes only light of a specific wavelength, and a filter section 41 that passes only light of a specific wavelength, and a filter section 41 that passes only light of a specific wavelength.
A motor 47 rotates a disc-shaped filter A consisting of a dark filter part 42 and a disc-shaped mask 46 formed with a part 44 that transmits the plasma light 2 and a part 45 that blocks it. It is integrally fixed to the shaft 48.

The phase of the filter 43 and the mask 46 is such that the ratio of the intensity of the plasma light 2 collected by the light collection means and the plasma light 2a of the specified chemical name contained in this plasma light 2 is large, that is, When the plasma light 2a of the specific chemical species is extremely small compared to the plasma light 2, in order to prevent a decrease in detection accuracy in the light detection means 5, the plasma light 2a is
Since the light amount is set to be reduced at a predetermined ratio 0 This is 4Q g, the part A4 of the mask 46 crosses the original axis of the two plasma beams projected from the lighting means 6. When the light passes through the mask +16 and reaches the filter 43, and when the portion 45 crosses the optical axis, it is MUM'd by the mask 46 and does not reach the filter 43. When the plasma light 2 reaches the filter 45,
. When the filter portion 41 crosses the front axis, only the plasma light 2n of a specific wavelength in the plasma light 2 is transmitted and reaches the photodetecting means 5. When the neutral density filter section 42 crosses the optical axis of the plasma 920, the plasma light 2 whose light is attenuated at a predetermined ratio reaches the professional detection means 5. In this way, the plasma light 2 and the specific chemical contained therein! Heavy plasma light 2a can be taken out alternately.

The photodetector 5 includes a photoelectric converter 51 that receives the plasma light 2, 2a that has passed through the spectrometer 4 and converts it into an electrical signal corresponding to the intensity of the plasma light 22a; The amplifier 52 amplifies the electrical signal to a size suitable for signal processing, and the rotation of the amplifier 47 (
That is, the filter 410 rotation) phase is detected to determine whether the electrical signal applied from the amplifier 52 is the electrical signal 21 corresponding to the plasma light 2 or the electrical signal 21a corresponding to the plasma light 2a. The discriminator circuit 53 is configured by a discriminator circuit 53.

The control means 6 includes three motors 51 of the lighting means 6.
5, 520 (the other one is not shown) to move the lighting optical system 51 to a required position, and based on the commands given to the motors 515 and 620 (the other 1). The coordinates of the focal point 35 of the lens 34 of the lighting optical system 31 with respect to the plasma in the processing apparatus 1 (that is, the measurement position @) are given to the measuring means 7.

In the above configuration, the position in the processing apparatus 1 at which the plasma is to be measured is set and the control means 6 is controlled. and,
The lighting means 6 is operated by a command from the control means 60, and the lighting optical system 61 is positioned at the first measurement position. At this time, if plasma is generated and emitted within the processing device 1, the plasma light 2 at the measurement position will be transmitted to the lens 34. The light passes through the collimator 33 and enters the optical fiber 32, is guided by the optical fiber 32 to the spectroscopic means 4, and is emitted from the optical fiber halo 2. At this time, the operation of the motor 47 causes the mask 4 to
6 and the filter 43 are rotating, the plasma light 2 becomes
Plasma light 2 attenuated at a predetermined ratio and plasma light 2
The plasma light 2a of a specific wavelength (that is, the emission wavelength of a specific chemical species) contained therein is alternately projected from the spectroscopic means 4 to the photoelectric converter 51. Then, each plasma light 2,
2a are converted into electrical signals according to their respective intensities, amplified by an amplifier 52, discriminated by a discrimination circuit 53, and applied to the measuring means 7 as electrical signals 21, 21a. Then, the electric signals 21 and 21a are compared by the measuring means 7, and the concentration of the specific chemical species in the plasma at the measurement position is determined.

Then, the coordinates of the measurement position and the concentration applied from the control means 6 to the measurement means 7 are applied to the display means 8 and/or the recording means 9, and are displayed and recorded.

The concentration distribution of the specific chemical species in the plasma can be determined by sequentially moving the measurement positions based on the commands of the control means B and determining the concentration of the specific chemical species in the plasma at each measurement position. .

Note that if the filter 4 of the spectroscopic means 4 is configured with two types of filter sections 41 that transmit different wavelengths, it is possible to detect the concentrations of two types of specific chemical species contained in the plasma. Become.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to measure the concentration distribution of a specific chemical species (for example, Ali or AlCl in the case of aluminum etching) in the plasma generated in the processing apparatus 1. , the processing status (for example, the end point in the case of etching) can be accurately grasped. Furthermore, it is possible to grasp changes in machining conditions and obtain information for appropriately controlling machining conditions.

In addition, since only one photodetection means is required, there are no errors in the photodetection means1, and the entire device can be made compact and supplied at low cost, which is an extremely advantageous effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a monitor according to the present invention, FIG. 2 is an enlarged partial sectional view showing the condensing optical system of the condensing means in FIG. 1, and FIG. FIG. 4 is a front view showing the scanning mechanism of the condensing means, and FIG. 4 is a side view of FIG. 3. 2...Plasma light 3...Lighting means 4...Spectroscopy means 5...Light detection means 6...Control means 7...5 measuring means 8...Display means 9...Recording total

Claims (1)

[Claims] 1. Sequentially select plasma measurement positions, collect plasma light at 1 g of each measurement position, and collect plasma light from each measurement position for all chemical species constituting the plasma. The plasma light emitted by the plasma and the plasma light emitted by the specific chemical species contained in the plasma are separated and detected, and based on these detection results, the concentration of the specific chemical species at each measurement position is calculated. A plasma monitoring method characterized by fully measuring the distribution state of the concentration of specific chemical species contained in the plasma. 2.Sequentially select the plasma measurement position #, collect the plasma light at each measurement position, and use the plasma light collected from each measurement position to detect two types of chemical species among all the chemical species that make up the plasma. The 2fi [ 1. A method for monitoring plasma, comprising: determining a distribution of ratios of specific chemical species of type 1. 3. A lighting optical system is provided that faces the window of the processing equipment H and receives plasma light at the measurement position in the processing equipment through the window, and the measurement position is determined by moving this lighting optical system in three dimensions with respect to the window. a light collecting means to select; a spectroscopic means for separating the plasma light collected by the light collecting means into two types of plasma light to be detected; and a spectroscopy means for alternately receiving the two types of plasma light separated by the spectroscopic means. In addition to converting and amplifying the electrical signal corresponding to the intensity of the plasma light,
A light detection means for determining which of the two types of plasma light the electric signal corresponds to, and a control means for instructing the light collecting means of the measurement position of the plasma and transmitting a coordinate signal of the measurement position with respect to the plasma. is connected to the photodetection means and the control means, and measures a specific chemical species based on two electrical signals applied from the photodetection means, and also measures the measurement result and a coordinate signal applied from the control means. A plasma monitor, comprising: a measuring means that corresponds to the measuring means; and a displaying means and/or recording means connected to the measuring means and displaying and/or recording the coordinates of the measurement position and the measurement results applied from the measuring means. 4. A patent characterized in that the lighting optical system is constituted by an optical fiber, a collimator provided at the end of the optical fiber on the lighting side, and a lens provided at the end of the collimator on the lighting side. A plasma monitor according to claim 6. 5. The spectroscopy means rotates the rotational driving means to rotate the mask that opens and closes the optical path of the plasma light emitted from the lighting means and the filter that separates the plasma light that has passed through the mask into two types of plasma light to be detected. 4. The plasma monitor according to claim 3, wherein the plasma monitor is supported on a shaft. 6. The plasma monitor according to claim 5, wherein the filter is constituted by a pair of filters each having wavelength selectivity that allows only plasma light of a specific wavelength to pass through. 7. A patent claim characterized in that the filter is constituted by a filter having wavelength selectivity that passes only plasma light of a specific wavelength, and a filter having less wavelength selectivity and having a light attenuation characteristic. Plasma monitor 0 described in scope 5