JPH04291345A - Pattern formation method - Google Patents

Abstract

PURPOSE:To allow the elimination of alignment and electron beam plotting, the improvement in throughput and the formation with good reproducibility and to improve the yield of non-defective reticules. CONSTITUTION:Patterned level differences 1a are formed on a substrate 1 by forming a 1st film 2 on the substrate 1, etching the 1st film 2 to form patterned 1st film patterns 2a on the substrate 1, forming a 2nd film 3 so as to cover the 1st film patterns 2a, anisotropically etching the 2nd film 3 to form side wall films 3a on the side walls of the 1st film patterns 3a, etching the substrate 1 with the 1st film patterns 2a and the side wall films 3a as a mask, and further removing the side wall films 3a.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more particularly to a pattern forming method that can be applied to photolithography technology in the manufacture of semiconductor integrated circuits, and in particular can improve throughput and yield.

[0002] In recent years, there has been a demand for higher integration of LSIs, and there is a demand for larger LSI chips while miniaturizing circuit patterns. For this reason, efforts are being made to improve the resolution of exposure equipment, but the current speed of pattern miniaturization is outpacing the improvement of the performance of exposure equipment, and recently the phase shift method, which is a device for masks (reticles), has become popular. There is a need for stable formation of phase shift masks.

0003

[Prior Art] Conventional edge-enhancing phase shift masks have to be manufactured using an extremely tricky method, even though the width of the phase shifter around the edge must be precisely set and manufactured. Ta. For example, a phase shift film is formed on a pattern formed of a light shielding film, and then, after alignment is performed and a resist pattern is formed, the phase shift film is etched.

0004

[Problems to be Solved by the Invention] However, in the conventional pattern forming method for forming the above-mentioned phase shift mask, the throughput is poor due to the necessity of alignment, electron beam lithography, etc. The width of the shifter at the edge changes, making it difficult to form reticles with good reproducibility, resulting in problems such as a low yield of good reticles.

Therefore, the present invention can eliminate the need for alignment and electron beam lithography, improve throughput, and form reticles with good reproducibility, thereby improving the yield of good reticles. The purpose is to provide a pattern forming method.

[0006]

[Means for Solving the Problems] In order to achieve the above object, a pattern forming method according to the present invention includes forming a first film on a substrate, and then etching the first film to form a pattern on the substrate. forming a first film pattern of
A second film is formed to cover the film pattern, and then
The second film 3 is anisotropically etched to form a sidewall film on the sidewall of the first film pattern, and then the substrate is etched using the first film pattern and the sidewall film as a mask. A patterned step is formed on the substrate by removing the sidewall film.

[0007]

[Operation] FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, 1 is a substrate, 1a is a patterned step formed on the surface of the substrate 1, 2 is a first film formed on the substrate 1, and 2a is a pattern formed by etching the first film 2. 3 is a second film formed to cover the first film pattern 2a; 3a is the second film 3 formed on the side wall of the first film pattern 2a by anisotropic etching; This is the sidewall membrane.

Next, the pattern forming method will be explained. First, as shown in FIG. 1(a), a first
After forming the film 2, as shown in FIG. 1B, the first film 2 is anisotropically etched to form a first film pattern 2a. At this time, the substrate 1 is exposed.

Next, as shown in FIG. 1C, after forming a second film 3 to cover the first film pattern 2a, as shown in FIG. 3 is removed by anisotropic etching so that the second film 3 remains at least on the side wall of the first film pattern 2a, thereby forming a side wall film 3a on the side wall of the first film pattern 2a. At this time, the substrate 1 is exposed.

Then, the substrate 1 is anisotropically etched using the first film pattern 2a and the sidewall film 3a as a mask (FIG.
(e)), by further removing the side wall film 3a, FIG.
A patterned step 1a on the surface of the substrate 1 as shown in (f)
It is possible to obtain a pattern formed by

As described above, in the present invention, the sidewall film 3a is formed with a uniform width on the sidewall of the first film pattern 2a in a self-aligned manner, and the sidewall film 3a is formed with a uniform width on the sidewall of the first film pattern 2a, which becomes a light shielding film. The width of the phase shifter and the position of the outer pattern edge (X section shown in FIG. 1(f)) are determined by the width of the sidewall film 3a formed with a uniform width on the sidewall of the first film pattern 2a. Therefore, the width of the phase shifter and the position of the pattern edge can be made substantially equal such that a=b as shown in FIG. 1(f). Therefore, it is extremely effective in forming an edge-enhanced phase shift mask, and can be formed with good reproducibility, thereby improving the yield of reticle manufacturing. Note that it is only necessary to control the thickness of the side wall film 3a;
At present, this can be done with control within ±5%.

[0012] Also, it can be formed in a self-aligned manner,
Moreover, since alignment and electron beam lithography can be made unnecessary, the throughput of reticle manufacturing can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. FIG. 2 is a diagram illustrating a pattern forming method according to an embodiment of the present invention, and the illustrated example is a case where the pattern forming method is applied to a phase shift mask forming method. In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, 4 is a resist formed on the first film 2, and 4a is a resist pattern formed by patterning the resist 4. In FIG.

Next, the pattern forming method will be explained. First, as shown in FIG. 2(a), a light-shielding film 2b made of Cr or the like is formed on a substrate 1 made of synthetic quartz or the like for transmitting exposure light. As shown in FIG. 2(c), the resist 4 is patterned by exposure and development to form a resist pattern 4.
form a.

Next, as shown in FIG. 2(d), the Cr film 2b is anisotropically etched using the resist pattern 4a as a mask, and as shown in FIG. 2(e), the Cr film 2b and the resist pattern 4a are etched. After forming a second film 3 (not shown) made of polysilicon, for example, to cover it, the second film 3
is anisotropically etched to form resist pattern 4a and Cr.
A sidewall film 3a is formed on the sidewall of the film 2b.

Then, the resist pattern 4a, the Cr film 2
By etching the substrate 1 using the resist pattern 4a and the sidewall film 3a as a mask, and further removing the resist pattern 4a and the sidewall film 3a, a patterned step 1a was formed on the surface of the substrate 1 as shown in FIG. 2(f). You can get the pattern.

That is, in this embodiment, the substrate 1 is an exposure light transmitting substrate used in an exposure apparatus, and one layer of light shielding film 2 is used.
In this case, the sidewall film 3a is formed with a uniform width on the resist pattern 4a and the sidewall of the light shielding film 2b in a self-aligned manner, and the width of the phase shifter around the edge of the light shielding film 2b and the outer pattern are Since the position of the edge (X section shown in FIG. 2(f)) is determined by the width of the sidewall film 3a formed with a uniform width on the sidewall of the light shielding film 2b, the phase shifter width and the position of the pattern edge are They can be made approximately equal. Therefore, it is extremely effective in forming edge-enhanced phase shift masks, and can be formed with good reproducibility.
The yield of reticle manufacturing can be improved. Note that it is only necessary to control the thickness of the sidewall film 3a, and at present it can be controlled within ±5%. Further, since the reticle can be formed in a self-aligned manner and alignment and electron beam lithography are not required, the throughput of reticle manufacturing can be improved.

Next, in the present invention, a substrate may be used in which one layer (at least one layer or more) of the third film is formed on the surface of the substrate. , as shown in FIG. 3(a), a third SiO2 film 5 is formed on the substrate 1, and a first poly-Si film 2 is formed on the third film 5.
After forming the first film 2 and anisotropically etching the first film 2 to form the first film pattern 2a, as shown in FIG. 3(b),
A PSG second film 3 is formed to cover the first film pattern 2a. Next, as shown in FIG. 3C, the second film 3 is anisotropically etched to form a sidewall film 3a on the sidewall of the first film pattern 2a, and as shown in FIG. The third film 5 is anisotropically etched using the first film pattern 2a and sidewall film 3a as masks, and the sidewall film 3a is further removed to form a step on the substrate 1. In this case, since a step can be formed on the substrate 1, when forming an insulating layer such as SiO2 or PSG to cover the first film pattern 2a and the third film 5, it is possible to form a step in a vertical shape. A wiring layer can be formed with better coverage than when covering a pattern.

Next, in FIG. 3, the case where SiO2 is used for the third film 5 has been described, but in the present invention, an exposure light transmitting film may be used for the third film 5. Specifically, as shown in FIG. 4(a), a substrate 1 is made of a material that transmits exposure light (for example, OCD: manufactured by Tokyo Ohka Co., Ltd.).
After forming a P third film 5 and a first film 2 that is a light shielding film such as Cr, and forming a resist pattern 4a on the first film 2 as shown in FIG. As shown in (c), the first film pattern 2a is formed by anisotropically etching the first film 2 using the resist pattern 4a as a mask. Next, as shown in FIG. 4(d), the first film pattern 2
A second film made of, for example, polysilicon or PSG is formed to cover the resist pattern 4a and the resist pattern 4a, and the second film is anisotropically etched to form a sidewall film on the sidewalls of the first film pattern 2a and the resist pattern 4a. Form 3a. Then, as shown in FIG. 4(e), the first film pattern 2a,
The third film 5 is anisotropically etched using the resist pattern 4a and the sidewall film 3a as a mask, and then the resist pattern 4a and the sidewall film 3a are removed to form a step on the substrate 1. In this case, the same effect as the embodiment of FIG. 2 can be obtained.

Next, in the present invention, the substrate 1 is an LSI
It may be a wafer substrate on which PS is formed on the Si substrate 1. Specifically, as shown in FIG. 5(a), PS
G. A third film 5 is formed, a first film pattern 2a is formed on the third film 5, and the third film 5 is formed using the first film pattern 2a as a mask as shown in FIG. 5(b). After performing anisotropic etching (stopped midway so as not to expose the substrate 1), a sidewall film 3a is formed on the sidewall of the first film pattern 2a, as shown in FIG. 5(c). Then, as shown in FIG. 5D, the third film 5 is anisotropically etched using the first film pattern 2a and the second film 3 as a mask to expose the substrate 1,
As shown in FIG. 5E, a step is formed on the substrate 1 by removing the first film pattern 2a and the sidewall film 3a. In this case, the same effect as the embodiment of FIG. 3 can be obtained.

Next, in the present invention, the first film may be formed of multiple layers. Specifically, as shown in FIG. 6(a), a Cr film is formed on the substrate 1. 2b and PS
A first film 2 made of a G film 2c is formed, and as shown in FIG. 6(b), a resist 4 is formed on the first film 2 by resist coating, and as shown in FIG. 6(c), Resist pattern 4 is formed by patterning resist 4 by exposure and development.
After forming the PSG film 2c, as shown in FIG. 6D, the PSG film 2c is anisotropically etched using the resist pattern 4a as a mask, and the resist pattern 4a is removed. Then, as shown in FIG. 6(e), a poly-Si sidewall film 3a is formed on the sidewall of the PSG film 2c, and as shown in FIG. 6(f), a Cr film 2b is formed using the PSG film 2c and the sidewall film 3a as a mask. Etching is performed, and the sidewall film 3a is further removed to form a step on the substrate 1.

Next, in FIG. 6, the case where the sidewall film 3a is formed on the sidewall of the PSG film 2c has been described.
A sidewall film 3a may be formed on the sidewalls of the PSG film 2b and the PSG film 2b shown in FIG. 6(d).
After forming the c pattern, as shown in FIG. 7(a), the Cr film 2b is anisotropically etched using the PSG film 2c pattern as a mask to form a Cr film 2b pattern, and as shown in FIG. 7(b), A sidewall film 3 is formed on the sidewalls of the PSG film 2c and the Cr film 2b.
a, and as shown in FIG. 7(c), a PSG film 2c,
The substrate 1 is etched using the Cr film 2b and the sidewall film 3a as a mask, and the sidewall film 3a is further removed to form a step on the substrate 1.

In FIGS. 6 and 7, the case where the resist pattern 4a is removed after forming the PSG film 2c pattern has been described, but the next step may be carried out with the resist pattern 4a remaining. Specifically, as shown in FIG. As shown in a), the PSG film 2c is anisotropically etched using the resist pattern 4a as a mask to form a PSG film 2c pattern.
As shown in FIG. 8B, after forming a sidewall film 3a on the sidewalls of the resist pattern 4a and the PSG film 2c without removing the resist pattern 4a, as shown in FIG. Then, the Cr film 2b is anisotropically etched using the sidewall film 3a as a mask, and the resist pattern 4a and the sidewall film 3a are further removed to form a step on the substrate 1.

In FIG. 8, resist pattern 4a and PS
Although the case where the sidewall film 3a is formed on the sidewall of the G film 2c has been described, the resist pattern 4a, the PSG film 2c and the Cr
A sidewall film 3a may be formed on the sidewall of the film 2b. Specifically, as shown in FIG. 9(a), the PSG film 2c and the Cr film 2b are anisotropically etched using the resist pattern 4a as a mask. As shown in FIG. 9(b), after forming a sidewall film 3a on the sidewalls of the resist pattern 4a, the PSG film 2c, and the Cr film 2b, as shown in FIG. 9(c), the resist pattern 4a, the PSG film 2c are , the substrate 1 is etched using the Cr film 2b and the sidewall film 3a as masks, and the resist pattern 4a and the sidewall film 3a are further removed to form a step on the substrate 1.

Next, in the present invention, as shown in FIG. 10, the formation of the second film, the subsequent anisotropic etching of the second film, and the etching of the substrate are repeated to form a multi-patterned step. It is also preferable that the step can be made gentler, and when forming a wiring layer of Al or the like on the step, it can be formed with better coverage.

Next, in the present invention, as shown in FIG. 11, the formation of the second film and the subsequent anisotropic etching of the second film are repeated to form multiple sidewalls, and then one part of the sidewalls is formed. After only the sidewalls are removed, the substrate may be etched to form a multi-pattern step. In this case, the present invention can be preferably applied to the formation of multi-pattern steps in LSI manufacturing and the like. It can also be applied to the formation of special types of phase shift reticles.

[0027]

[Effects of the Invention] According to the present invention, it is possible to eliminate the need for alignment and electron beam lithography, improve the throughput of reticle production, and also make it possible to form reticles with good reproducibility. It has the effect of being able to improve the

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2 is a diagram illustrating a pattern forming method according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 4 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 5 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 6 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 7 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 8 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 9 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 10 is a diagram illustrating a pattern forming method applicable to the present invention.

FIG. 11 is a diagram illustrating a pattern forming method applicable to the present invention.

[Explanation of symbols]

1　　　　Substrate 1a Step 2 First film 2a First film pattern 3 Second film 3a Side wall membrane 4 Resist 4a Resist pattern 5 Third film

Claims (8)

[Claims] 1. A first film (2) is formed on a substrate (1), and then the first film (2) is etched to form a patterned first film on the substrate (1). A pattern (2a) is formed, then a second film (3) is formed to cover the first film pattern (2a), and then the second film (3) is formed to cover the first film pattern (2a).
A sidewall film (3a) is formed on the sidewall of the first film pattern (2a) by anisotropic etching, and then the first film pattern (2a) and the sidewall film (3a) are used as a mask to form a sidewall film (3a) on the sidewall of the substrate. (1) and further removes the sidewall film (3a) to form a patterned step 1a on the substrate 1. 2. The pattern according to claim 1, wherein the substrate is an exposure light-transmissive substrate used in an exposure apparatus, and the first film pattern film includes at least one light-shielding film. Formation method. 3. At least one third layer on the surface of the substrate.
2. The pattern forming method according to claim 1, wherein a substrate having a film formed thereon is used. 4. The pattern forming method according to claim 3, wherein a material transparent to exposure light is used for the third film. 5. The pattern forming method according to claim 1, wherein the substrate is a wafer substrate on which a semiconductor element is formed. 6. The pattern forming method according to claim 1, wherein the first film is formed of multiple layers. 7. A pattern characterized in that the formation of the second film according to claim 1 and subsequent anisotropic etching of the second film and etching of the substrate are repeated to form a multi-patterned step. Formation method. 8. Repeating the formation of the second film according to claim 1 and the subsequent anisotropic etching of the second film,
A pattern forming method comprising forming multiple sidewalls, removing only a portion of the sidewalls, and then etching the substrate to form multiple patterned steps.