JPH104045A - Semiconductor integrated circuit device, method of manufacturing the same, and manufacturing apparatus - Google Patents

Abstract

(57) [Problem] To improve measurement accuracy of a wafer position in an exposure optical axis direction at the time of focusing or leveling adjustment at the time of pattern exposure. SOLUTION: Measurement sites 4 are provided at four corners of an exposure region 3 on a semiconductor wafer 1, and the measurement sites are irradiated with probe light to measure the position of the semiconductor wafer 1 in the exposure optical axis direction. Further, the surface shape of the measurement site 4 is fixed to a flat or specific pattern. As a result, measurement site 4
To specify the reflection position of the probe light at. Further, in the exposure apparatus, there is provided a measurement position variable mechanism capable of changing the irradiation position of the probe light and the light receiving position of the reflected probe light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device, a manufacturing technique therefor, and a manufacturing apparatus therefor, and more particularly to a technique effective when applied to formation of a fine pattern requiring fine processing.

[0002]

2. Description of the Related Art As a well-known technique for forming a fine pattern in a manufacturing process of a display device such as a semiconductor integrated circuit device, a printed circuit board, or a liquid crystal, there is a photolithography technology as is well known.

An exposure apparatus used for photolithography is described in, for example, "LSI Handbook", published by Ohm Co., Ltd. on November 30, 1984, p425-p42.
As described in No. 6, a transfer method for transferring a pattern on an original onto a processing target is mainly used.
There are known an equal-magnification projection method in which an original and an object to be processed are placed close to each other to project exposure light, and a reduction projection method in which exposure light is projected via an imaging optical system.

In these photolithography processes, it is important to control the positions of the original plate and the object to be processed. That is, in the 1 × projection method, the distance between the original and the surface of the object to be processed, and in the reduced projection method, the positional relationship between the original, the imaging surface of the optical system, and the surface of the object to be processed is important.
If these cannot be controlled accurately, the yield of products will be reduced due to the occurrence of defective resolution, defective dimensions, and the like.

Accordingly, the above positional relationships are adjusted, that is, leveling for adjusting the parallelism between the image plane and the surface of the workpiece in the original or reduced projection system in the 1: 1 projection system, and the projection of the surface of the workpiece. Focusing for adjusting the position in the optical axis direction needs to be performed accurately.

[0006]

The leveling or focusing described above includes (a) an air micro method for determining a distance between a reference surface and a surface to be measured by a pressure loss of a blown gas, or (b) an oblique direction. By irradiating the surface to be measured with light and measuring the distance from a certain reference plane, such as a reflected light method by measuring the position of the reflected light, a method of measuring the distance from a certain reference plane is adopted. He came to recognize that the measurement had the following problems.

[0007] Problems are listed below.

(1) Normally, μ
Although there are various steps on the order of m, in the measurement of the surface position, since it usually has an area of several square mm,
It is unknown which part in the surface to be measured, that is, which height or average height of the surface of the workpiece is being measured.

For this reason, it is necessary to reset the focusing conditions each time the original pattern is different so as to obtain the optimum resolution. Moreover, this resetting requires extracting a pattern with the smallest depth of focus and adjusting the focusing position to this pattern, which is a time-consuming and complicated operation.

(2) For leveling the surface of the object to be processed, surface position measurement cannot be performed at one point, and measurement at a plurality of points is required. It is very unlikely that the surface steps are equal in these measurement areas at a plurality of points, and it is generally considered that they are different. In such a case, the setting of the leveling condition which requires the same procedure as the setting of the focusing condition described in the above (1) becomes more complicated.

(3) In the case of an exposure apparatus of a type in which exposure is repeated within a semiconductor wafer to be processed, such as a step-and-repeat type, for example, the surface positions of a plurality of points described in (2) above for each exposure shot Measurement is performed. However, in the exposure apparatus mainly used at present, since the measurement area for surface position measurement is fixed, at the array end of the repeated exposure area, a part of the measurement area for the surface position is shifted from the pattern formation area in the array. It may come off. In this case, since the surface shape inside the pattern formation region is usually different from the surface shape outside the pattern formation region, the leveling condition set in the above (2) should be As a result, the leveling adjustment includes an error.

(4) A step-and-scan method can be cited as an exposure method expected next to the current mainstream step-and-repeat method. In the case of the step-and-scan method, the above-mentioned items (1) to (3) are used. The difficulty in leveling or focusing adjustments is expected to be even greater. That is, it is necessary to know the relationship between the position of the surface of the processing object in the direction of the exposure optical axis at each moment of scanning and the optimum focusing position at that moment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for manufacturing a semiconductor integrated circuit device having a high pattern resolution by improving the accuracy of leveling adjustment or focusing adjustment at the time of exposure, and a semiconductor integrated circuit device that can be used for the manufacture. To provide.

It is another object of the present invention to provide a method and apparatus for manufacturing a semiconductor integrated circuit device which facilitates setting of conditions for leveling adjustment or focusing adjustment at the time of exposure, and a semiconductor integrated circuit device which can be used for the manufacture. Is to do.

Still another object of the present invention is to provide a method and an apparatus for manufacturing a semiconductor integrated circuit device which can cope with a method requiring higher precision such as a step-and-scan method in leveling and focusing adjustment, and to provide them. It is an object of the present invention to provide a semiconductor integrated circuit device which can be used.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0017]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

(1) A method of manufacturing a semiconductor integrated circuit device according to the present invention includes a photolithography step in which a resist pattern is formed by irradiating projection light of an original pattern onto a surface of a semiconductor wafer. A measurement part for specifying the position of the semiconductor wafer in the optical axis direction of the projection light is provided on the surface of the semiconductor wafer, the measurement part is irradiated with the probe light, and the reflected probe light of the probe light is measured to automatically perform the measurement. Focusing or leveling is performed.

According to such a method of manufacturing a semiconductor integrated circuit device, a measurement portion for specifying the position of the semiconductor wafer in the projection optical axis direction is provided on the surface of the semiconductor wafer,
Since this is irradiated with probe light to measure the position of the semiconductor wafer, the position measurement of the semiconductor wafer for focusing or leveling can be accurately performed.

That is, in the conventional method in which no measurement site is provided, if a step or an arbitrary shape exists in the area to be measured, the probe light is reflected at any height or at any average height. Although it is unclear whether or not the measurement site is provided, the reflection height of the probe light can be specified, and as a result, the accuracy of position measurement can be improved.

Although it is clear that the reflection position of the probe light is clearly on the surface when the surface shape of the measurement site is flat, when the surface shape of the measurement site has a step, it is obvious. It is not clear at what height the probe light is being reflected. However, as long as the surface shape of the measurement site is the same, the manner of reflection of the probe light does not change. Therefore, once an empirical reflection position is specified by an experiment, the empirical specified position is used as a reference thereafter. Position measurement.

(2) The method of manufacturing a semiconductor integrated circuit device according to the present invention is the manufacturing method according to (1), wherein the focusing or leveling is performed in the optical axis direction of the projection light obtained by measuring the reflected probe light. This is performed by referring to the position information of the semiconductor wafer and the offset information having a certain correlation with the surface shape or the surface step of the semiconductor wafer in the region irradiated with the projection light.

According to such a method of manufacturing a semiconductor integrated circuit device, focusing or leveling is performed with respect to the position information of the semiconductor wafer and the surface shape or surface step of the semiconductor wafer in a region irradiated with the projection light. Since the adjustment is performed by referring to the offset information having a correlation, accurate focusing or leveling can be performed.

That is, if there is a step or a pattern on the surface to be measured only by referring to the position information of the semiconductor wafer, it is unknown which height is being measured. At the same time as measuring the surface of the determined height by measuring the measurement site, and referring to the offset information unique to the step or pattern of the projection light irradiation area, based on the measurement height of the measurement site. . In other words, the offset information is adjusted so that optimum focusing or leveling is achieved in the projection light irradiation area.

The adjustment of the offset information can be performed in advance by performing conditions on a surface where a step or a pattern is evident, and testing the offset conditions for optimal focusing or leveling. Further, a step or a pattern of the projection light irradiation area may be simulated from the layout design data, and an offset value may be theoretically calculated from the simulated information without any experience, and used as offset information.

(3) The method of manufacturing a semiconductor integrated circuit device according to the present invention is the manufacturing method according to the above (2), wherein the offset information has a minimum depth of focus extracted from the resist pattern with reference to the measurement site. This is given as a difference in height between portions.

According to such a method of manufacturing a semiconductor integrated circuit device, since the offset information is given as a height difference between the measurement site and a portion having the minimum depth of focus, focusing and leveling can be performed accurately.

That is, among the patterns in the projection light irradiation area, since the focusing on the pattern having the minimum depth of focus is the most critical, the offset information is set so as to focus on the pattern having the minimum depth of focus. It was made.

(4) The method for manufacturing a semiconductor integrated circuit device according to the present invention is the method as described in (1) to (3) above,
The measurement site is provided in a scribe line area of a semiconductor wafer.

According to such a method of manufacturing a semiconductor integrated circuit device, since the measurement site is provided in the scribe line region of the semiconductor wafer, the semiconductor wafer can be effectively used without waste.

That is, since the measurement site is used only in the exposure process, it is not necessary as a function of the semiconductor integrated circuit device. Therefore, in the final product, a measurement site is provided in an area that is scribed and disappears, thereby eliminating waste.

(5) The apparatus for manufacturing a semiconductor integrated circuit device according to the present invention is an apparatus for manufacturing a semiconductor integrated circuit device for irradiating a resist formed on the surface of a semiconductor wafer with projection light of an original pattern to expose the resist. Means for irradiating probe light to a measurement site provided on the surface of the semiconductor wafer for measuring the position of the semiconductor wafer in the optical axis direction of the projection light, reflected probe light of the probe light reflected by the measurement site Reflection probe light measuring means for measuring
With reference to the optical axis direction position of the semiconductor wafer measured by the reflection probe light measuring means, and offset information having a constant correlation with the surface shape or surface step of the semiconductor wafer in the region irradiated with the projection light. Optical axis direction position adjusting means for performing focusing or leveling.

According to such a semiconductor integrated circuit device manufacturing apparatus, the position of the semiconductor wafer in the optical axis direction measured by the reflection probe light measuring means and the surface shape or surface of the semiconductor wafer in the region irradiated with the projection light Since there is an optical axis direction position adjusting means for executing focusing or leveling with reference to offset information having a certain correlation with the step, focusing or leveling is performed for the same reason as described in (2) above. Can be done accurately.

(6) The manufacturing apparatus of a semiconductor integrated circuit device according to the present invention is the manufacturing apparatus according to the above (5), wherein the probe light irradiating means and the reflected probe light measuring means are each provided with a semiconductor to which the probe light is irradiated. A measurement position variable mechanism capable of changing a position on the wafer is provided.

According to such an apparatus for manufacturing a semiconductor integrated circuit device, since the measurement position variable mechanism is provided, it is possible to cope with measurement sites provided at different locations depending on the product type or chip size.

That is, in a conventional manufacturing apparatus for a semiconductor integrated circuit device such as an exposure apparatus, it is not allowed to change the area to be measured in terms of hardware, but in the manufacturing apparatus of the present invention, the irradiation position of the probe light is changed. By changing it, it corresponds to the position of a different measurement site. In the present invention, since the manufacturing apparatus is provided with the probe light irradiation means and the reflection probe light measurement means, it is easy to respond to such a demand.

(7) A semiconductor integrated circuit device according to the present invention is a semiconductor integrated circuit device in which a semiconductor integrated circuit element is formed on a main surface of a semiconductor substrate. A measurement part used for leveling measurement is provided.

According to such a semiconductor integrated circuit device,
Since the measurement site is provided, the accuracy of the alignment in the exposure optical axis direction is improved, and the reliability and yield of the semiconductor integrated circuit device can be improved.

(8) The semiconductor integrated circuit device of the present invention is the semiconductor integrated circuit device according to the above (7), wherein a measured part is correlated with an offset value at the time of focusing measurement or leveling measurement. Alternatively, it has a surface step or a flat surface.

According to such a semiconductor integrated circuit device,
By specifying the shape of the measurement site, it is possible to precisely determine at which height the measurement is being performed. As a result, the accuracy at the time of exposure is improved,
The reliability and the yield of the semiconductor integrated circuit device can be improved.

[0041]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a top view showing a semiconductor wafer to which a method of manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention is applied.

In the first embodiment, a case where the present invention is applied to exposure of a step-and-repeat method will be described.

On the semiconductor wafer 1, a semiconductor integrated circuit element is formed, and a chip area which is a chip 2 is formed.

In the first embodiment, the exposure region 3
Consists of two chip areas. That is, two chip areas are exposed simultaneously.

Measurement sites 4 as measurement sites are provided at four corners of each exposure region 3. The surface shape of the measurement site 4 may be, for example, a surface of a metal film having no pattern, or a specific pattern may be provided. If you have a specific pattern,
The pattern shape needs to be fixed within a wafer, between wafers, or between products. In other words, once the condition is set for the specific pattern, the offset value obtained at that time is a value specific to the specific pattern, and changing the pattern requires the condition to be set again. It is.

As described above, by providing the measurement sites 4 at the four corners of the exposure region 3, the measurement region can be specified and used as a reference for focusing or leveling adjustment at the time of exposure.

FIG. 2 is a side view showing a main part of an exposure apparatus which is an apparatus for manufacturing a semiconductor integrated circuit device according to the first embodiment.

The semiconductor wafer 1 is held on a fine movement stage 6 installed on the wafer stage 5, and is moved between the exposure regions 3 by moving the wafer stage 5, and the focusing or leveling adjustment is performed by the fine movement stage 6. Of the semiconductor wafer 1 is performed.

The exposure light 7 is emitted from an unillustrated ultraviolet light source, shaped by an appropriate optical system, and then irradiated onto a reticle 9 held by a reticle holder 8. Since the first embodiment exemplifies the reduced projection exposure method, the reticle 9 uses a pattern having a size five times as large as the actual pattern, but it can have any magnification of 1 or more.

The exposure light 7 transmitted through the reticle 9 passes through the image forming optical system 10 and irradiates the exposure area 3 of the semiconductor wafer 1. At this time, the pattern of the reticle 9 is 1/5
And irradiated.

Prior to the irradiation of the exposure light 7, a focusing or leveling operation for matching the image formation surface of the exposure light 7 with the optimum image formation surface of the surface of the semiconductor wafer 1 is required.

In the first embodiment, the position measurement of the semiconductor wafer 1 for focusing and leveling is performed by using the probe light 14 emitted from the light emitting element 11 and passing through the slit 12 and the position measurement optical system 13. The light is irradiated on the measurement site 4 provided above, reflected here, and the reflected probe light 15 that has passed through the position measurement optical system 13 is measured by the light receiving element 16 to determine the position of the measurement site 4 in the direction of the exposure light 7. Detect and perform.

Focusing and leveling are performed so that each position of the measurement site 4 obtained by the position measurement and the image plane of the pattern image of the reticle 9 determined by the image forming optical system 10 are maintained at a predetermined distance. Done by Here, the predetermined distance indicates a bias value that differs depending on a circuit pattern provided in a chip region on the semiconductor wafer 1. That is, a bias value, which is a deviation between a measured value and a target value, is formed when a feedback loop is formed to perform an automatic control by sensing a position measurement result of the measurement site 4 and realizing an optimum focus state or an optimum level state. This must be set in advance according to the pattern on the semiconductor wafer 1. The bias value is set for the semiconductor wafer 1
The condition is determined for each of the above patterns or theoretically obtained by calculation.

As described above, the measurement site 4 is positively provided, and focusing or leveling is performed by measuring the measurement site 4. , The accuracy of measurement can be significantly improved. That is, conventionally, since the pattern was an arbitrary pattern, the height at which the probe light 14 was reflected was different for each pattern. However, in the first embodiment, the measurement site 4 is specified, and the surface shape of the measurement site 4 is further determined. Since the pattern is also specified, the reflection height of the probe light at the time of focusing or leveling adjustment is always reflected in the same state and can be reflected at the same height. As a result,
It is not necessary to repeat the condition for the pattern once the condition has been completed, which simplifies the manufacturing process and can contribute to cost reduction, improvement in yield, and the like.

Further, the exposure apparatus of the first embodiment is provided with a rotary encoder 17 which is a measurement position changing means capable of changing the irradiation position of the probe light 14 and an angle variable mirror 18. At the same time, the reflected probe light 1
A rotary encoder 17 and a variable angle mirror 18 are also provided as variable measuring position means for deviating the light receiving position of No. 5. By these measurement position changing means, there is no need to fix the position of the measurement site 4 on the semiconductor wafer 1, and the measurement site 4 can be provided at an arbitrary position.

Although the position of the measurement site 4 may be provided inside the chip 2, in the first embodiment, it is provided inside a scribe line outside the chip 2. Therefore, after the semiconductor wafer 1 is scribed and cut, the measurement site 4 is also shaved and disappears.
Does not contribute to the function of the semiconductor integrated circuit device at all, and is rather preferable, and the area of the semiconductor wafer 1 can be effectively utilized. Further, unlike the chip 2, there is no complicated step in the scribe line, so that more accurate focusing or leveling can be performed.

The spot diameter of the probe light 14 is about 5
In this case, the measurement within the scribe line can be sufficiently performed.

As described above, prior to the exposure in each exposure area 3, the position of the exposure light 7 at the four measurement sites 4 in the optical axis direction is measured for each of the exposure areas 3 using the above-described measurement mechanism. By controlling the height or rotation of the semiconductor wafer 1 by the fine movement stage 6, highly accurate focusing and leveling can be performed.

(Embodiment 2) FIG. 3 is a top view showing an exposure area for one chip when the measurement method described in Embodiment 1 is applied to a step-and-scan type exposure apparatus.

In the second embodiment, on both sides of the chip 2,
A strip-shaped measurement site 19 is provided.

The exposure area 20 is formed linearly over the measurement sites 19 on both sides of the chip 2 and is scanned in the vertical direction.

According to such a method of manufacturing a semiconductor integrated circuit device, the height of the chip 2 at the location where the exposure light is being exposed is measured in real time while the exposure light is scanning the exposure area 20. Can be. Thus, it is possible to execute focusing and leveling adjustment at the same time as scanning, even during scanning, instead of performing focusing and leveling of the chip 2 prior to scanning at the time of scanning exposure and fixing the values until scanning is completed.

As a result, the exposure in the step-and-scan method can be performed with high accuracy, which can contribute to the improvement of the performance of the semiconductor integrated circuit device and the improvement of the yield. Further, it is possible to easily cope with a request for increasing the size of the chip 2.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the invention. Needless to say, it can be changed.

For example, in the first embodiment, the case of the reduced projection exposure method has been described, but it goes without saying that the invention may be applied to the same size projection exposure.

In the first embodiment, the measurement sites 4 are
Although the example in which the parts are provided has been described, it goes without saying that three or five or more places may be provided. At this time, everything may be provided in the scribe line,
All may be provided in the area of the chip 2. Further, a part thereof may be provided in the scribe line, and the other may be provided in the chip 2 region.

Further, in the first and second embodiments, the case of the semiconductor wafer 1 has been described, but the substrate may be glass or ceramic.

[0069]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) A measuring portion for specifying the position of the semiconductor wafer in the projection optical axis direction is provided on the surface of the semiconductor wafer, and the position of the semiconductor wafer is measured by irradiating the measuring portion with the probe light. Measurement of the position of the semiconductor wafer can be accurately performed.

(2) Focusing or leveling refers to the position information of the semiconductor wafer and offset information having a certain correlation with the surface shape or surface step of the semiconductor wafer in the region irradiated with the projection light. , Accurate focusing or leveling can be performed.

(3) Since the offset information is given as a height difference between the measurement site and the portion having the minimum depth of focus, focusing and leveling can be performed accurately.

(4) Since the measurement site is provided in the scribe line area of the semiconductor wafer, the semiconductor wafer can be effectively used without waste. In addition, highly accurate focusing and leveling can be performed using the flat surface.

(5) Since the measurement position variable mechanism is provided, it is possible to cope with measurement sites provided at different locations depending on the product type or chip size.

[Brief description of the drawings]

FIG. 1 is a top view showing a semiconductor wafer to which a method of manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention is applied.

FIG. 2 is a side view showing a main part of an exposure apparatus which is a manufacturing apparatus of the semiconductor integrated circuit device according to the first embodiment.

FIG. 3 is a top view showing an exposure region for one chip when a method of manufacturing a semiconductor integrated circuit device according to another embodiment of the present invention is applied to a step-and-scan exposure apparatus.

[Explanation of symbols]

 Reference Signs List 1 semiconductor wafer 2 chip 3 exposure area 4 measurement site 5 wafer stage 6 fine movement stage 7 exposure light 8 reticle holder 9 reticle 10 imaging optical system 11 light emitting element 12 slit 13 position measuring optical system 14 probe light 15 reflection probe light 16 light reception Element 17 Rotary encoder 18 Variable angle mirror 19 Measurement site 20 Exposure area

Claims (8)

[Claims] 1. A method for manufacturing a semiconductor integrated circuit device, comprising: a photolithography step in which a resist pattern is formed by irradiating a projection light of an original pattern onto a surface of a semiconductor wafer, wherein the projection is performed on the surface of the semiconductor wafer. Providing a measurement site for specifying the position of the semiconductor wafer in the optical axis direction of light, irradiating the measurement site with probe light, measuring the reflected probe light of the probe light, and automatically performing focusing or leveling. A method of manufacturing a semiconductor integrated circuit device. 2. The manufacturing method according to claim 1, wherein the focusing or the leveling is performed on position information of the semiconductor wafer in an optical axis direction of the projection light obtained by measuring the reflection probe light, and the projection light. And a offset information having a fixed correlation with a surface shape or a surface step of the semiconductor wafer in a region to be irradiated with the semiconductor integrated circuit device. 3. The manufacturing method according to claim 2, wherein the offset information is given as a height difference of a portion having a minimum depth of focus extracted from the resist pattern with reference to the measurement site. A method for manufacturing a semiconductor integrated circuit device. 4. The method according to claim 1, wherein the measurement site is provided in a scribe line region of the semiconductor wafer. 5. An apparatus for manufacturing a semiconductor integrated circuit device, which irradiates a resist formed on a surface of a semiconductor wafer with projection light of an original pattern and exposes the resist, wherein the semiconductor is arranged in an optical axis direction of the projection light. Probe light irradiating means for irradiating probe light to a measurement site provided on the surface of the semiconductor wafer for measuring the position of the wafer; reflected probe light for measuring the reflected probe light of the probe light reflected at the measurement site Measuring means, a constant correlation between the position of the semiconductor wafer in the optical axis direction measured by the reflection probe light measuring means and a surface shape or a surface step of the semiconductor wafer in a region irradiated with the projection light. Optical axis direction position adjustment means for executing focusing or leveling with reference to offset information having a relationship. Apparatus for manufacturing a semiconductor integrated circuit device according to claim Rukoto. 6. The manufacturing apparatus according to claim 5, wherein the probe light irradiation unit and the reflection probe light measurement unit can change a position on the semiconductor wafer to which the probe light is irradiated. An apparatus for manufacturing a semiconductor integrated circuit device, comprising a variable measurement position mechanism. 7. A semiconductor integrated circuit device in which a semiconductor integrated circuit element is formed on a main surface of a semiconductor substrate, wherein a measurement portion used for focusing measurement or leveling measurement in a photolithography process is provided on a part of the semiconductor substrate. A semiconductor integrated circuit device characterized in that: 8. The semiconductor integrated circuit device according to claim 7, wherein the measurement site is a surface shape or a surface step correlated with an offset value at the time of the focusing measurement or the leveling measurement, or a flat surface; A semiconductor integrated circuit device characterized by having: