JPH02242175A - Apparatus for evaluating heat resistance of resist - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for evaluating the heat resistance of resists such as photoresists and electron beam resists used in the production of semiconductor devices, RC devices, and the like.

<Prior Art> Semiconductor elements, IC elements, and the like are used in computers, various electrical products, and the like.

Manufacture of such elements is generally carried out by photo-etching.

The method of manufacturing an element by photoetching is to first form an electrode layer on an insulating substrate by a method such as vapor deposition or sputtering, and then apply a photoresist dissolved in a solvent to the electrode layer using a method such as a spin code. Apply.

After the photoresist is multiphased, the photoresist solvent is evaporated by a heat treatment called bribague.

Next, this photoresist is covered with a photomask and exposed by irradiation with light or laser light, and then developed with a prescribed developer. For example, if the photoresist is positive type, the exposed area will be dissolved. In this way, a microresist having a predetermined particularly fine resist pattern is formed.

After the development is completed, the formed microresist is subjected to a heat treatment called "bost bake" for the purpose of strengthening the etching resistance and evaporating the developer.

After the formation of the microresist is completed, etching is performed at night to dissolve the electrode layer on which the microresist layer is not formed and form a conductor layer in a predetermined pattern, which is applied to semiconductor devices and IC devices. Ru.

By the way, in order to form a microresist to be applied to photoetching, two heating steps, blibator and boss bake, are performed in the manufacturing process as described above. Therefore, it is formed into a predetermined resist pattern,
Applicable resists include at least this bribeta,
Heat resistance higher than the boiling temperature is required.

Such resist heat resistance tests are usually performed by measuring changes in the shape of the resist pattern before and after heating. Conventionally, this measurement was performed using an optical microscope or scanning electron microscope (SEM). This was done by direct observation.

However, this heat resistance evaluation method involves directly observing the resist pattern with the naked eye, and cannot quantitatively measure changes in the shape of the resist pattern, making it impossible to accurately evaluate the heat resistance of the resist. .

In addition, observation by SEM is a destructive test that requires cutting the sample into nine small pieces, and therefore has the problem of being very time-consuming.

In order to solve such problems, the present inventors irradiated coherent light onto a resist pattern formed on a substrate, diffracted the coherent light by the formed resist pattern, and removed the non-zero-order diffracted light. He invented a method for measuring changes in the shape of a resist pattern by measuring the strength of the resist pattern, and proposed this method earlier (Japanese Patent Application No. 63-253262).
.

According to this method, it is possible to quantitatively measure changes in the shape of a resist pattern, and by applying this method, it is possible to quantitatively and accurately evaluate the heat resistance of a resist, and to cut the sample into sections. It can be done without the need.

<Problems to be Solved by the Invention> In order to evaluate the heat resistance of a resist using the method described above, first, a sample in which a microresist having a fine resist pattern is formed on a substrate is prepared and heated.

``This sample is fixed on a sample mounting table, coherent light is irradiated onto the microresist, and the intensity of the diffracted light other than the 0th order is measured using a photodiode or the like.

The above measurements are performed at a plurality of temperatures, and changes in the shape of the microresist are measured from changes in the intensity of diffracted light to evaluate the heat resistance of the resist.

In order to perform accurate measurements, it is of course necessary that the positional relationship between the optical system such as the laser light source and photodiode and the sample remains exactly constant at all times. In some cases, it is necessary to place the sample before heating and the sample after heating at exactly the same location on the sample mounting table.

However, the resist pattern formed on the microresist is very fine, and it is extremely difficult to fix the sample at the same location on the sample stage again at this level.

Therefore, it is desirable to heat the sample while it is mounted on the sample mounting table, but the laser light source used for measurement
Photodiodes and the like have a high temperature dependence, and the heat generated during sample heating affects measurements, making it impossible to perform accurate heat resistance evaluations.

For example, the guaranteed temperature is 60℃, and the He-Ne laser is 63℃.
If a photodiode with a sensitivity of 0.4 A/W at 3 nm is used, the measured current is usually 10-5 ~
Since the dark current is about 10-'A, it is necessary to suppress the dark current to about 10-6 to 101A in order to perform accurate measurements. To this end, it is desirable that the ambient temperature during measurement be 40° C. or lower, and in order to perform accurate measurements, it is necessary that the heat generated during heating of the sample not affect the optical system during measurement.

An object of the present invention is to solve the problems of the prior art described above, and it is possible to easily and quantitatively evaluate the heat resistance of a resist, and there is no need to move the sample during measurement, and there is no need to move the sample during the measurement. To provide a resist heat resistance evaluation device that can perform accurate measurements without being affected by heat and can also measure changes over time while heating the microresist to be measured. be.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a resist heat resistance evaluation apparatus for evaluating the heat resistance of a resist formed on a substrate, which comprises: a light source that irradiates the resist with coherent light; , a measuring device that measures the intensity of diffracted light other than the 0th order of the coherent light that is incident on the resist and diffracted; a heating device that heats the resist; and between the resist, the light source, and the measuring device. Provided is a resist heat resistance evaluation device characterized by having a transparent heat shield plate arranged therein.

<Operation of the Invention> The resist heat resistance evaluation device of the present invention heats a sample on which a microresist having a predetermined, particularly fine resist pattern is formed on a substrate, places it at a predetermined position, and then heats the sample to place it at a predetermined position. Coherent light is irradiated, the intensity of the diffracted light other than the 0th order is measured, and the shape change of the resist pattern is measured from the change in the intensity of the diffracted light, and the temperature at which the microresist starts to change shape and the degree of shape change are measured. This is an apparatus for evaluating the heat resistance of a resist, and has a transparent heat shield plate between a sample on which a microresist is formed on a substrate, a coherent light source, and a diffracted light intensity measuring device.

Therefore, according to the resist heat resistance evaluation apparatus of the present invention, it is possible to easily and quantitatively evaluate the heat resistance of a resist without preparing a sample section or the like.

In addition, since the resist heat resistance evaluation device of the present invention has a transparent heat shield plate between the microresist, the coherent light source, and the measuring instrument, the heat resistance evaluation device of the present invention has a transparent heat shield plate between the microresist, the coherent light source, and the measuring instrument. There is no adverse effect on the light source and the measuring device, accurate measurements can be made, and even during heating, the adverse effect of heat on the light source and the measuring device can be prevented.

Furthermore, since it is possible to measure the intensity of the diffracted light while heating the sample, it is also possible to measure changes over time in the microresist due to heating.

Furthermore, the resist heat resistance evaluation apparatus of the present invention does not require moving the sample from the sample mounting stage during heating, etc., and the positional relationship between the light source and the measuring instrument and the sample does not move (always constant and always accurate). It is possible to evaluate heat resistance.

<Embodiments> Hereinafter, a resist heat resistance evaluation apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a conceptual diagram of a preferred embodiment of the resist heat resistance evaluation apparatus of the present invention.

The resist heat resistance evaluation apparatus 10 shown in FIG.
A laser light source 16 that irradiates the sample 12 with laser light as coherent light, a photodiode 18 that measures the intensity of diffracted light other than the 0th order of the laser light incident on the sample 12 and diffracted; It is composed of a heating device 20 for heating, a transparent heat shield plate 22, and a control device 24.

The resist heat resistance evaluation apparatus 10 of the illustrated example irradiates a laser beam from a laser light source 16 to a microresist of a sample 12 heated by a heating device 20, and diffracted light other than the 0th order of the diffracted light diffracted by the microresist. The intensity is measured by the photodiode 18.

Similar measurements are performed at a plurality of temperatures, and changes in the shape of the microresist are measured from changes in the intensity of diffracted light at each temperature, thereby evaluating the heat resistance of the resist.

A method for measuring changes in the shape of a microresist using such a laser beam is described in detail in Japanese Patent Application No. 63-253262 filed by the present applicant.

The sample 12 applied to the present invention has a microresist formed on a substrate. As the substrate, a silicon wafer, a glass plate, etc. can be suitably used.

The resist to be measured in the present invention can be measured regardless of whether it is a positive type or a negative type, and is not particularly limited. .

Note that the resist pattern of the microresist is preferably one in which stripe-like patterns are formed at equal intervals in order to facilitate the alignment of the optical axis and to receive diffracted light other than the 0th order without waste.

The sample mounting table 14 supports such a sample 12 at a predetermined position.

The sample mounting table 14 may simply be used to place the sample 12 on it, as long as it can position and place the sample 12 in a predetermined position, or it may be fixed by various means such as suction. It's okay.

Further, when the base material of the sample 12 is a silicon wafer, it is preferable to have a positioning means corresponding to the orientation flat that silicon wafers usually have.

Although such a sample mounting table 14 may be fixed at a predetermined position, it is configured to be movable in the vertical direction and parallel direction by various means, and is configured to be movable in the vertical direction and parallel direction. It is preferable that the irradiation position of the laser beam on the sample 12 can be changed accordingly.

Above the sample mounting table 14 is a laser light source 16 that irradiates the microresist formed on the sample 12 with laser light.
is placed.

In the present invention, as the laser light source 16, various types having wavelengths outside the photosensitive range of commonly used resists can be used, and there is no particular limitation, such as He-Ne laser, gas laser, semiconductor laser, etc.

Such a laser light source 16 may be configured so that the irradiation position of the laser light can be moved as necessary.

At the top of the sample mounting table 14 on the side opposite to the laser light source 16, there is a sample! A photodiode 18 is arranged to measure the intensity of diffracted light other than the 0th order of the laser light that is incident on the microresist 20 and diffracted.

The photodiode 18 constitutes a measuring instrument of the resist heat resistance evaluation apparatus 10 of the present invention. The measuring device is not particularly limited as long as it can measure the intensity of laser diffracted light other than the zero-order, and various photodetectors are applicable, and it is not limited to the photodiode 18 shown in the figure, but may also include phototransistors, photodetectors, etc. Examples include image sensors, electronic circuits incorporating these, and the like.

Here, in the resist heat resistance evaluation apparatus 1° of the present invention, in order to more accurately measure the shape of the microresist, the microresist formed on the sample 12 has the above-mentioned striped resist pattern. It is preferable that the diffracted light measured by the photodiode 18 be second-order or higher-order diffracted light.

The photodiode 18 is not particularly limited, and various types such as a pn photodiode, a pin photodiode, a Schottky photodiode, and various avalanche photodiodes such as St and Ge are applicable, and there is no particular limitation.

Note that in the illustrated example, the photodiode 18 is arranged at a position where it does not receive the zero-order diffracted light a;
The present invention is not limited to this.

A heating device 20 is arranged below the sample mounting table 14 .

The heating device 20 supports the sample 12 placed on the sample mounting table 14.
A device that heats the liquid to a desired temperature, and various hot plates, heaters, etc. are applicable.

Moreover, such a heating device 20 may be configured to be movable by a rack-and-binion, a drive screw, a ball screw, or the like, if necessary.

Note that the resist heat resistance evaluation apparatus 10 of the present invention may be configured so that the sample 12 can be placed directly on a predetermined position of the heating device 20. In this case, a sample mounting table 14 may be provided. is not necessary.

Further, in this case, it is preferable that the heating device 20 is provided with means such as suction so that the sample 12 can be securely fixed.

A transparent heat shield plate 22 is placed between the sample 12, the laser light source 16, and the photodiode 18.

In the resist heat resistance evaluation apparatus 10 of the present invention, by having the heat shield plate 22, the sample 12 can be completely moved from the initially placed position in any operation before heating, during measurement of the diffracted light intensity, and during heating. There is no need to use the laser light source 16 and the photodiode 18 eight times. Therefore, it is possible to accurately measure the intensity of the diffracted light while the positional relationship between the laser light source 16, the photodiode 18, and the sample 12 is exactly the same before and after heating the sample 12.

Further, although the laser light source 16 and the photodiode 18 are highly temperature dependent, by having a heat shield plate 22, the laser light is irradiated onto the microresist through this and the diffracted light is measured. It is possible to measure the intensity of the diffracted light in a state where the heat of the heating device 20 does not affect the laser light source 16 and the photodiode 18 at all, and it is possible to accurately measure the shape of the microresist. . Therefore, sample 12
It is also possible to measure changes in the shape of the microresist over time while heating it, and it is also possible to measure the temperature dependence of the resist's heat resistance.

Further, the laser light source 16 and the photodiode 18 are not adversely affected even while the sample 12 is being heated.

In the resist heat resistance evaluation apparatus 10 of the present invention, the heat shield plate 2
Since 2 is placed above the sample 12, it is strongly required to have high heat resistance and a low coefficient of thermal expansion.

Note that, in order to perform accurate measurements, it is preferable that the coefficient of thermal expansion of the heat shield plate 22 is such that the rate of change in the thickness of the heat shield plate 22 is 1/32λ or less of the wavelength of the laser beam.

As such a transparent heat shield plate 22, various types of transparent heat absorption filters, a box-shaped heat shield plate having a 21i structure, etc. can be used.

Such a heat shield plate 22 may be configured to be movable by various means as necessary.

Moreover, the heat shield plate 22 and the above-mentioned heating device 20 may be configured integrally.

The control device 24 processes measurement data from the photodiode 18 and controls the movement of the heating device 20 and the heat shield plate 24, and basically includes a voltmeter 26 and an A/D converter 2.
8, an interface 30 and a CPU 32.

The output end of the photodiode 18 is connected to a voltmeter 26 . Data on the intensity of diffracted light other than the 0th order measured by the voltmeter 26 is converted from analog to digital by the A/D converter 28, and then sent to the CPU 3 via the interface 30.
2, and the data is processed by the CPU 32.

On the other hand, the CP passes through the heating device 20 and the interface 30.
It is connected to tJ32 and the heating temperature, heating time, etc. are controlled.

In addition, in the resist heat resistance evaluation apparatus 10 of the present invention,
Microresist shape measurement, temperature control, etc.
It may be input by various manual means and automatically controlled by the CPtJ32, or it may be performed manually.

The operation of the resist heat resistance evaluation apparatus 10 of the present invention will be explained below with reference to FIG.

First, a sample 12 on which a microresist having a fine resist pattern is formed on a substrate is placed at a predetermined position on the sample mounting table 14, fixed as necessary, and heated to a desired temperature.

Next, as shown in FIG. 1, a laser beam is irradiated from the laser light source 16 and is incident on the microresist.
The diffracted light of orders other than the 0th order enters the photodiode 18.

The intensity of each diffracted light incident on the photodiode 18 is measured by a voltmeter 26, and then the intensity of each diffracted light is measured by the A/D converter 2.
The data is analog-to-digital converted at 8, and processed and stored by the CPU 32 via the interface 30.

Next, the sample 12 is further heated in the heating device 20,
Similarly, the intensity of the diffracted light is measured and processed and stored in the CPU 32.

When all the measurements of the diffracted light at the desired temperature are completed as described above, the data obtained is organized in the CPU 32, and the change in the shape of the microresist is measured from the change in the intensity of the diffracted light, and the shape of the microresist is The heat resistance of the resist is evaluated based on the temperature at which the change begins and the degree of shape change.

As above, the resist heat resistance evaluation apparatus of the present invention has been described in detail based on the preferred embodiment shown in the attached drawings, but the present invention is not limited thereto, and within the scope of the gist of the present invention. Of course, various changes and improvements may be made.

<Effects of the Invention> The resist heat resistance evaluation device of the present invention heats a sample in which a microresist is formed on a substrate, irradiates the microresist with coherent light, and measures the intensity of diffracted light other than the 0th order of the diffracted light. The change in the shape of the microresist is measured from the change in the intensity of this diffracted light, and the heat resistance of the resist is evaluated. It has a hot plate.

Therefore, according to the present invention, without preparing a sample section of a microresist formed in the shape of a substrate, it is possible to easily
Furthermore, it is possible to quantitatively evaluate the heat resistance of the resist.

In addition, since the resist heat resistance evaluation device of the present invention has a transparent heat shield plate between the microresist, the coherent light source, and the measuring instrument, the resist heat resistance evaluation device of the present invention has a transparent heat shield plate between the microresist, the coherent light source, and the measuring instrument. Not only can accurate measurements be performed without adversely affecting the light source and measuring instrument, but also the adverse influence of heat on the light source and measuring instrument can be prevented even during heating.

Furthermore, since it is possible to measure the intensity of the diffracted light while heating the sample, it is also possible to measure changes over time in the microresist due to heating.

Furthermore, the resist heat resistance evaluation device of the present invention does not require moving the sample from the sample mounting stage during heating, etc., and the positional relationship between the light source, the measuring device, and the sample remains constant without moving, and the resist heat resistance is always accurate. can be evaluated.

30...interface, 32...CPU 4,

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a resist heat resistance evaluation apparatus of the present invention. Patent applicant Fuji Photo Film Co., Ltd. Representative Patent attorney Minoru Watanabe Code explanation 10... Resist heat resistance evaluation device, 12... Sample, 14... Sample mounting table, 16... Laser light source, 18... Photodiode, 20... Heating device, 22... Heat shield plate, 24... Control device, 26... Voltmeter, 28... A/D converter,

Claims (1)

[Claims] (1) A resist heat resistance evaluation device that evaluates the heat resistance of a resist formed on a substrate, comprising: a light source that irradiates the resist with coherent light; and non-zero-order diffracted light of the coherent light that is incident on the resist and diffracted. A resist heat resistance evaluation comprising: a measuring device for measuring the intensity of the resist; a heating device for heating the resist; and a transparent heat shield plate disposed between the resist, the light source, and the measuring device. Device.