JPH03173219A - Manufacture of element having pattern structure - Google Patents

Abstract

PURPOSE:To attain accurate pattern transfer of even a minute pattern by varying a phase difference of a lighting light transmitted through a pattern opening periodically, moving a wafer and eliminating a connection border region whose phase difference changes suddenly with a 2nd exposure. CONSTITUTION:A phase difference is supplied to lighting light transmitted through a pattern opening 1 with phase shift regions 4 of inverse-L shape complementarily in the vertical direction in an interdigital pattern comprising one opening pattern 1 and two interdigital light shield patterns 2, 3. That is, a phase difference of 0 deg. is given to a region 5 of opening pattern and a phase difference of 180 deg. is given to the phase shift region 4 of the opening pattern. SiO2 of a prescribed thickness is provided to the region 4. When patterns are formed on the wafer by using the phase shift reticle, the interdigital patterns are formed. However, exfoliation of the pattern takes place in the connection part 6 of the opening pattern. Thus, the phase shift pattern is used to move the position of the wafer with respect to the circuit pattern on a fixed photo mask by a prescribed quantity to transmit 2nd light, thereby forming the pattern.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing an element having a pattern structure, and particularly to a method suitable for manufacturing a surface acoustic wave element.

[Conventional technology]

A photomask with a circuit pattern of an electronic device, etc.
Projection/exposure equipment that illuminates a reticle with an irradiation optical system and transfers a circuit pattern onto a substrate wafer is required to be able to miniaturize the pattern that can be transferred. As a means of transferring fine patterns near the resolution limit of such pattern transfer devices, a method has been proposed in which a phase difference is applied to illumination light that passes through adjacent openings across a fine light-shielding portion on a photomask. There is. Regarding the conventional pattern formation method that gives a phase difference, see IE Transactions on Electron Devices 29 (1
982) pp. 1282 et seq. (IE E E, T
rans, on E 1ectron Device
s. Vol. ED-29, No. 12 (1982) p. 1
Mark Day Lebunson (M. 282~)
“Im
providing Re5solution inPhoto
olithography with a phase
-Shifting Mask". The pattern formation method proposed in this document is based on the technique of applying illumination light that passes through adjacent openings across a light-shielding part.
It provides a phase difference of 80° and is suitable for improving the resolution of periodically arranged patterns.

[Problem to be solved by the invention]

However, the above-mentioned prior art is effective only when adjacent openings are separated from each other. When adjacent openings are connected at a certain portion, it is impossible to provide a phase difference because the openings are continuous, so there is a problem in that pattern formation and resolution cannot be improved. In addition, in the circuit pattern of an actual electronic device,
Adjacent linear open patterns are often connected at their ends. In the conventional pattern forming method that provides a phase difference, the phase of the illumination light suddenly changes at this connection part, resulting in a region where the phase difference becomes 0.
Although the pattern is resolved, the pattern also separates in areas where it should be connected. Therefore, there was a problem that a desired continuous pattern shape could not be obtained on the wafer. An object of the present invention is to provide a method for forming a pattern that enables accurate pattern transfer even for a fine pattern in which adjacent open patterns are connected at a certain portion, and a method for manufacturing an element having the pattern. It's about doing. [Means for Solving the Problems] In order to achieve the above object, the present invention provides illumination that passes through continuous open patterns when adjacent linear open patterns are connected at their ends via a light shielding part. In the boundary region, which gives a phase difference to the light and where the phase of the illumination light suddenly changes at the connection part, for example, the phase of the second illumination light (second exposure) can be changed by slightly changing the relative position of the wafer with respect to the irradiation light. The pattern is configured to be different from the boundary area, which changes suddenly, so that the pattern does not separate at the part where it should be connected. Furthermore, in order to achieve the above object, the present invention is configured such that the phase difference of the illumination light transmitted through the continuous open pattern is changed continuously or stepwise inside the continuous open pattern. Furthermore, in order to achieve the above object, the continuous aperture pattern is partially divided and arranged in a plurality of photomasks, and the illumination light that passes through the aperture pattern on each of the divided and arranged photomasks is 180°. By periodically imparting a phase difference of This structure eliminates the boundary region where the phase of the illumination light suddenly changes at the part to be connected, and prevents the patterns from separating. [Function 1] By periodically imparting a phase difference of 180° to the illumination light that passes through the continuous aperture portions that are in contact with each other on the circuit pattern, the resolution of pattern transfer is improved. A slight change in the wafer position is achieved by using the second illumination light (
By the second exposure), the phase difference of the illumination light is O
. Or it acts so that it becomes 18o°. Thereby, a continuous pattern shape can be formed without separating the pattern at the portion of the open pattern to be connected. In addition, changing the phase difference of the illumination light continuously or stepwise near the connection part of the open pattern works to prevent the patterns from separating at the part where adjacent openings are connected at one end. However, a pattern with continuous openings can be formed. A first photomask, which is obtained by partially dividing a continuous opening pattern and arranging the divided patterns to give a phase difference, is formed by resolving the divided opening pattern. In this first photomask, the apertures are arranged so as to be separated by light-shielding parts, so there is no boundary area where the phase of the illumination light passing through the aperture changes suddenly, that is, an area with poor pattern resolution. , and the resolution of the pattern can be improved. A second photomask obtained by arranging the divided patterns and giving a phase difference is formed by resolving the divided opening patterns. And also in this second photomask. Since the opening portions are arranged so as to be independently separated from each other, it is possible to improve the resolution of the pattern without causing a region with poor pattern resolution. The first one like this
By combining patterns that can be resolved with a second photomask and forming patterns on the same substrate wafer, the phase difference between the illumination light caused by the connection of the openings of adjacent patterns becomes zero. It acts so that a boundary area does not occur. Therefore, it is possible to form a continuous pattern shape in which the patterns do not separate at the portions where continuous opening patterns should be connected. (Example) An example of the present invention will be described below with reference to FIG. 1st
The figure shows an interdigital pattern consisting of one continuous open pattern 1 formed by combining continuous comb-shaped patterns 1 and two comb-shaped light-shielding patterns 2 and 3 on a photomask to which the present invention is applied. It is. The dimensions of the portion where the open pattern and the light-shielding pattern intersect with each other in the figure are 0.25 μm on the wafer, respectively. In this case, since a 1/10 reduction projection exposure method is used, on a 10x reticle, these dimensions are each 2.5 μm. Here, as shown in FIG. 1(b), the illumination light passing through the open pattern 1 is given a phase difference by the upwardly and downwardly complementary inverted-shaped phase shift layers 4. That is, the phase difference is 0° in the region 5 of the open pattern, and 1 in the phase shift layer region 4 of the open pattern.
A phase difference of 80° is given. The phase shift layer 4 is provided with a thickness of about 0.38 μm and a size of 5 in 2 . The value of this thickness d satisfies the relationship λ 2 (n-1), where n is the refractive index of 5in2 and λ is the wavelength of the illumination light. The phase of the light is 1 compared to the phase of the illumination light that passes through the region 5 of the open pattern where no phase shift layer is provided.
Shifted by 80°. Note that the width of the opening provided with the phase shift layer is as shown in the figure. The width of the shift layer is the same as the size of the aperture, that is, 2.5 μm on a 10x reticle. A shift layer may be applied to the light shielding portion. However, due to the principle of the 1 phase shift method, it is not allowed to extend the shift layer to the next opening on the pattern. When a pattern is formed on a wafer using the phase shift reticle formed in this way, the exposure wavelength λ = When using an i-line 1/10 reduction projection exposure apparatus with a wavelength of 365 nm and a reduction lens numerical aperture NA=0.42, a comb-shaped interdigital pattern with a dimension of 0.25 μm can be resolved. However, as shown in FIG. 1(b), at the connection part 6 of the opening where the phase of the illumination light changes suddenly,
Pattern separation occurs. Therefore, in the present invention, (b
), as shown in (Q) of the figure, the position of the wafer is moved by 0.20 μm relative to the circuit pattern on the fixed photomask, and the second illumination light (second (exposure) was transmitted to form a pattern on the wafer. In (C) of the figure, 7 and 7' are (
Figure b) shows a region that was a light-shielding area that became an opening due to the movement of the wafer position, and 8 shows an opening where a phase shift was formed in part (b) of the figure, where there is no phase shift layer due to the movement of the wafer position. The area that became the opening is shown, and 8' is (
b) shows a region where light originally passed through the opening, but which becomes a light-shielding portion due to the wafer position movement. Also, the positions indicated by broken lines 9 and 9' in the figure are as follows. This is the position of the connecting portion 6 of the opening where the phase of the illumination light suddenly changes as shown in (b) of the figure. As can be seen from the figure, the positions of the connecting parts 10 and 10' of the opening where the phase of the illumination light changes suddenly in (c) of the figure change to the original connecting parts 9 and 9 due to the positional movement of the wafer. ′ (6 in figure (b)). As a result, the openings of the original connecting portions 9 and 9' are continuously connected by the transmission of the illumination light. In the newly formed connecting portions 10 and 10' of the openings, since the illumination light is transmitted through the openings as shown in FIG. 3(b), pattern separation does not occur. In this way, as shown in FIG.
．． It was possible to form a 25 μm interdigital pattern. As described above, according to the present invention, even a fine pattern in which adjacent open patterns are connected to form a continuous pattern as shown in (b) of the figure can be transferred without causing poor resolution. This makes it possible to fabricate a device with a fine interdigital pattern. FIG. 2 is a diagram showing an interdigitated finger pattern for explaining another embodiment of the present invention. Illumination light passing through the open lever pattern 1 shown in the figure is transmitted through three areas 11, 12.1 as shown in the figure.
Different phase differences are given in 3. That is,
In region 11, a phase difference of 0° is given, in region 12 a phase difference of 90", and in region 13 a phase difference of 180". In order to change the phase difference of the illumination light stepwise in one divided open pattern, the thickness of the phase shift layer, that is, SiO , the film thickness was changed. It goes without saying that the same effect can be obtained by changing the refractive index of the shift material of the shift layers 12 and 13. In this way, when the pattern is transferred, there is no connection part where the phase suddenly changes in the illumination light that passes through the apertures, so it is possible to form a comb-shaped interdigital pattern in which the pattern does not separate at consecutive apertures. Can be done. As described above, according to the present invention, the phase difference of the illumination light transmitted through the aperture is changed stepwise from Qo to 180°, so the light intensity distribution becomes zero during this period and the pattern are never separated. Therefore, it is possible to form a pattern with high resolution even for a fine pattern in which adjacent open patterns are connected and continuous. In addition, in the pattern forming method described above, the exposure wavelength λ = 365 nm and the numerical aperture NA of the reduction lens = 0.4.
This is an example in which an i-line 1/10 reduction projection exposure apparatus of 2 is used. In the phase shift pattern of the present invention and the conventional pattern forming method that does not apply double exposure, the pattern resolution limit was about 0.5 μm. In the embodiment described in the present invention, this resolution limit of 0.5 μm can be improved by about 50% to 0.25 μm, making it possible to manufacture an element having a fine interdigital pattern. By using the pattern manufacturing method of the present invention, when the exposure wavelength λ is shortened and used as excimer laser or X-ray, it is possible to further improve the resolution of the pattern, and it is possible to further improve the resolution of the pattern. Needless to say, formation is possible. Next, another embodiment of the present invention will be described with reference to FIG. FIG. 3 shows one continuous open pattern 1 formed by combining continuous comb-shaped shadows, and two comb-shaped light-shielding patterns 2 and 3 on a photomask to which the present invention is applied.
It is a diagram showing an interdigitated pattern consisting of. The dimensions of the portions where the open pattern and the light-shielding pattern intersect with each other in the figure are 0.25 μm on the wafer. In this case, a 1/10 reduction projection exposure method was used, so on a 10x reticle, these dimensions are each 2.5 μm. Such a continuous open pattern 1 is divided into a vertical opening and a horizontal opening. As shown in (b) of the figure, the illumination light transmitted through the vertical open pattern 14 formed on the first photomask passes through the light shielding part 15 and is alternately changed to a phase difference of 1806 by the phase shift layer 16. It is given. That is, the region 17 of the open pattern
In this case, the phase is Oo, and in the phase shift layer region 16 of the open pattern, the phase is 180°. In this case as well, the phase shift R16 is 5in2 with a depth of 0.38μm.
It is set up in Since the value of this thickness d satisfies the above-mentioned relationship, the phase of the illumination light transmitted through the phase shift layer region 16 is the open pattern region where no phase shift layer is provided. It is shifted by 180° compared to the phase of the illumination light transmitted through 17. Note that the width of the opening provided with the phase shift layer is the same as the width of the opening in the figure, that is, 2.5 μm on a 10x reticle. The purpose is to shift the phase of the light that passes through the aperture, as shown above.
A shift layer may cover adjacent light-shielding portions. However, due to the principle of the phase shift method, it is not allowed to extend the shift layer to the next adjacent opening on the pattern. When a pattern is formed on a wafer using the first phase shift mask (reticle) formed in this way, the exposure wavelength λ = 365 nm and the numerical aperture NA of the reduction lens =
When using an i-line 1/10 reduction projection exposure system with a diameter of 0.42, the resolution limit was approximately 0.5μ in the absence of a phase shift. , 25 μm grid pattern 18 can be resolved. Next, as shown in FIG. 5(a), a horizontal open pattern 19 obtained by dividing the continuous open pattern l shown in FIG. 3(a) formed on the second photomask is transmitted. The illumination light is alternately given a phase difference by the phase shift layers 21 via the light shielding parts 20. That is, the phase is Oo in the open pattern region 22, and the phase is 180'' in the open pattern phase shift layer region 21. Using the second phase shift mask (reticle) formed in this way, Then, a horizontal pattern with a size of 0.25 μm was formed as shown in (b) of the figure, matching the grid pattern 18 with a size of 0.25 μm formed on the wafer shown in FIG. As a result,
As shown in FIG. 6, a comb-shaped interdigital pattern 23 having exactly the same size of 0.25 μm as the pattern shown in FIG. 3(a) can be resolved. As a result, the connection part 2 of the opening part
4, the openings are continuously connected by the transmission of the illumination light of the first photomask and the second photomask. That is, since the illumination light from the first and second photomasks is transmitted through the connection portion 24, pattern separation does not occur. Therefore, even for fine patterns in which adjacent open patterns are connected and continuous, pattern transfer with high resolution is possible. In this way, as shown in FIG. 6, it is possible to form an interdigital pattern in which the size of the comb-shaped portion where the opening pattern and the light-shielding pattern intersect with each other is 0.25 μm at the opening and the light-shielding portion. The pattern forming method described here has a resolution limit of approximately 0.3
In excimer laser exposure, which is said to be .mu.m, the resolution limit can be improved by about 50% to about 0.15 .mu.m. As described above, according to the present invention, even for open patterns in which adjacent open patterns are connected and continuous, as shown in FIG. A method for manufacturing an element having a fine pattern can be provided. FIG. 7 is a diagram showing a comb-shaped interdigital electrode pattern for exciting surface acoustic waves (SAW) on a piezoelectric substrate for explaining another embodiment of the present invention. The illumination light transmitted through the open pattern 1 shown in the figure is given a phase difference of 180'' by the phase shift layer 4 as shown in the figure. However, the illumination light transmitted through the adjacent opening portion across the conventional light shielding portion When arranged with alternating phases of 0° and 18o°, in such a complex pattern, a region 25 where openings with a phase of 180° are adjacent to each other will occur, as shown by the circle in the figure. , poor pattern resolution occurs in this region. However, according to the phase shift layer formation and pattern formation method shown in FIGS. Since the phases of transmitted light are never equal, poor pattern resolution does not occur.As described above, according to the present invention, it is possible to form a complex fine interdigital electrode pattern such as that used in a SAW device. Further, according to the present invention, it is possible to form a surface acoustic wave element having a fine interdigital electrode pattern with a line width of about 0.25 μm as shown in FIG. Using such an element, it becomes possible to realize mobile communication equipment and ultrahigh-speed optical transmission equipment in the quasi-microwave band (1 to 3 GHz) and even higher frequency bands (up to 10 GHz). An example will be explained with reference to Fig. 8. Fig. 8 is a diagram showing a circuit wiring pattern on a photoreceptor formed by a continuous light-shielding pattern.
The opening 27 through which the illumination light is transmitted forms one continuous pattern due to the light shielding part 26 serving as the wiring pattern part. Here, in order to improve the resolution of the pattern, if phase shift layer regions are provided alternately in the opening pattern separated by the light shielding part, the phase of the light transmitted through the opening will be (b). In (b) of the figure, the phase of the transmitted light is such that a region 28 of 0° and a region 29 of 18° whose phase is inverted by the phase shift layer are arranged alternately. Therefore, when viewed from the AA' cross section in the figure, the resolution of the pattern is improved. However, in the conventional method of providing phase shift layers alternately, in the case of this circuit wiring pattern, as shown in (a) of the figure. Portion 30 where the phase difference of illumination light suddenly changes and the light intensity becomes zero
There are portions 31 where the phase of light is the same in adjacent openings separated by a light shielding portion, and the pattern cannot be resolved in these portions. However, FIGS. 1, 3 and 5 of the present invention
By using the pattern forming method shown in the figure, it is possible to give a phase difference to the illumination light between adjacent apertures even in a pattern with one continuous aperture, so that poor pattern resolution will not occur. Wiring patterns can be formed without any problems. Another embodiment of the present invention will be explained with reference to FIG. FIG. 9 is a diagram showing a circuit pattern on a photomask in which opening patterns are each independently formed in a light shielding part. In (a) of the figure, the openings 27 through which the illumination light passes are each in an isolated pattern within the light shielding section 26. Here, in order to improve the resolution of the pattern, if phase shift layer regions are provided alternately in the opening pattern, the phase of the illumination light will be B-
If you look at the concave cross section of B' and c-c', you will see a region 28 where the phase is 0° and a region 2 where the phase is 180°, as shown in (b) of the figure.
9 are arranged alternately, so the pattern is resolved. However, as shown in (c) of the figure, D-D'
When looking at the phase of the illumination light in the cross section, there is a portion 31 where the phases of the lights that pass through adjacent openings across the light shielding portion are 180° and have the same phase, and the resolution of the pattern cannot be improved in this portion. . However, according to the phase difference exposure process of the present invention, the pattern resolution can be improved even in such a circuit pattern, and even finer through-hole patterns for forming city poles can be formed. [Effects of the Invention] According to the present invention, by periodically changing the phase difference of the illumination light that passes through the pattern opening and moving the substrate tool, the phase difference can be suddenly changed by the second exposure. do(
Since the connection boundary area (where the light intensity becomes zero) disappears, the light intensity distribution does not become zero at the boundary area and the pattern does not separate. Furthermore, since the phase difference of the illumination light is changed stepwise from 0° to 180°, the aperture patterns will not be separated. Therefore, even for fine patterns in which open patterns that are adjacent to each other are continuous, there is an effect that the resolution can be improved by imparting a phase difference to the illumination light. Furthermore, since there is no region where the phase difference of transmitted light is equal between the openings, it is possible to form a complex fine comb-shaped interdigital electrode pattern such as that used in a SAW filter. Furthermore, the continuous open pattern is divided into one continuation part, each having an aperture separated by a light shielding part, and a phase difference is periodically given to the illumination light passing through the aperture.
The resolution of the pattern is greatly improved, and pattern separation, which occurs in the conventional case where the light intensity distribution becomes zero at the connection boundary area, which occurs due to a sudden change in phase difference, does not occur. Furthermore, it is possible to form a circuit wiring pattern or a through-hole pattern for electrode wiring in which the phase of illumination light becomes equal between the openings, and there is an effect that these patterns can be further miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a comb-shaped interdigital pattern having one continuous open pattern in which the pattern forming method of the present invention is implemented, and FIG. 2 is a diagram showing a comb-shaped interdigital pattern for explaining another embodiment of the present invention. 3 to 6 are diagrams showing interdigital patterns formed by dividing an opening pattern for explaining other embodiments. Electron of the surface acoustic wave device (diagram showing yellow pattern,
FIGS. 8 and 9 are diagrams showing a circuit wiring pattern and an electrode forming pattern to which the present invention is applied. Explanation of symbols 1...Open pattern, 2...Comb-shaped light-shielding pattern, 3...
・Comb-shaped light-shielding pattern, 4 ・Phase shift layer region, 5
・Opening pattern with a phase difference of 0°, 6. Connecting part of the opening where the phase suddenly changes, 7 and 7' ・A region that has become an opening,
8...A region that is an opening without a phase shift layer, 8'
・A region that became a light shielding part, 9 and 9'...position of the connection part 6, 10 and 10'...a connection part of the newly created opening, 11...a region with a phase difference of 0°, 12...Region with a phase difference of 90', 13...Area with a phase difference of 180°, 14.Long pattern in the vertical direction, 15...Light shielding part, 16...Phase shift layer, 17...Phase 0° Open pattern, 18...
- Grid pattern, 19... Open pattern divided in the horizontal direction, 20... Light shielding part, 21... Phase shift layer,
22... Opening pattern with phase O°, 23... Comb-shaped interdigital pattern, 24... Connecting portion of opening, 25
...A region where openings with a phase of 180° are adjacent, 26...
Light shielding part, 27...Aperture, 28...Area where the phase is O°, 29...A phase inversion area, 3o...A portion where the light intensity is zero, 31...The phase of the light is the same The part that becomes. \-Yo, 4 Funeral map (b) ¥ Figure 3 Figure (b) 5 Figure Figure 4 Kaya? Figure (of) c Cb) 1 7 Kaya 7 Figure CC)

Claims (1)

[Scope of Claims] 1. A method for manufacturing an element having a pattern structure, which comprises the following steps. (1) A first step of irradiating and exposing a plurality of adjacent regions with illumination light having a phase difference; (2) A second step of exposing a boundary portion of the plurality of regions; The method for manufacturing an element having a pattern structure, wherein the first step includes a step of irradiating each of the plurality of regions with illumination light having a phase difference of approximately 180°. 3. The method of manufacturing an element having a pattern structure according to claim 1, wherein the first step includes a step of exposing the illumination light in a desired pattern shape using a photomask. 4. The method for manufacturing an element having a pattern structure according to claim 3, wherein the second step includes a step of shifting the positions of the plurality of regions irradiated with the illumination light in the first step. A method for manufacturing an element having 5. The method for manufacturing an element having a pattern structure according to claim 1, wherein the first step is a step of using light having a phase difference continuously or intermittently as the illumination light. manufacturing method. 6. In the method for manufacturing an element having a pattern structure according to claim 5, in the first step, the illumination light is 0°.
A method for manufacturing an element having a pattern structure, the method comprising the step of using a phase difference between 180° and 180°. 7. The method for manufacturing an element having a pattern structure according to claim 1, wherein the second step includes a step of using a photomask for exposing the boundary portions of the plurality of regions. . 8. The method of manufacturing an element having a pattern structure according to claim 3, wherein the first step includes forming the plurality of regions by combining a plurality of photomasks. 9. The method for manufacturing an element having a pattern structure according to claim 1, wherein the first step includes a step of selecting a region surrounded by interdigital regions as the plurality of regions. Production method. 10. The method for manufacturing an element having a pattern structure according to claim 9, wherein the first step includes a step of selecting a thin film conductor region to be formed on the piezoelectric substrate as the interdigital region. Method of manufacturing elements.