JPH04332118A - Formation of pattern - Google Patents

Abstract

PURPOSE:To enable a pin hole as an entire second etching-resistance film to be reduced by forming first and second etching-resistance films on an object to be subjected to patterning and forming the second etching-resistance film by performing coating for two times. CONSTITUTION:A lower-layer resist film (first etching-resistance film) 11 is formed on an Al film as an object to be subjected to patterning on a substrate 9. Then, a middle-layer SOG film (second etching-resistance film) 12 is formed on the lower-layer resist film 11. After a first SOG is coated, heating treatment is performed and a lower-layer SOG film 12a is formed. After this, a second SOG is coated and heated and then an upper-layer SOG film 12b is formed. At this time, since the SOG film 12 is formed by coating which is performed two times, a possibility where pin holes are overlapped each other becomes extremely small even if the pin holes are produced at the SOG films 12a and 12b, thus nearly preventing pin holes from being produced as the entire middle- layer SOG film 12.

Description

[Detailed description of the invention]

[0001] (Table of Contents) - Industrial application fields - Conventional techniques (Figs. 5 and 6) - Problems to be solved by the invention (Fig. 7) - Means for solving the problems (Fig. 1) - Effects ( Figure 1) ・Example (Figures 2 to 4) ・Effects of the invention

0002

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 using a multilayer resist method.

In recent years, as the density of semiconductor integrated circuit devices has increased, there has been a demand for finer patterns. Conventionally, etching-resistant patterns have been formed using a single-layer resist method, but if the object to be patterned has unevenness, the difference in the thickness of the formed resist film will cause the focus to become uneven, making it difficult to obtain a sufficiently uniform pattern. Can't get resolution. Therefore, it is difficult to form fine etching-resistant patterns with high precision. For this reason, a so-called multilayer resist method such as a two-layer resist method or a three-layer resist method has come to be used.

0004

[Prior art] Figs. 5(a) to (c), Figs. 6(d), (e)
) is a cross-sectional view illustrating a pattern forming method using a conventional three-layer resist method.

First, a lower resist film 3 is formed on a patterned object 2 on a substrate 1 by a coating method. At this time, in order to flatten the unevenness of the object to be patterned 2, the lower resist film 3 is formed quite thick, and in order to prevent reflection of exposure light etc. from the object to be patterned 2 during exposure, The lower resist film 3 contains a light absorbing material.

Next, as an etching-resistant film for the lower resist film 3, an intermediate resist film 4 containing silicon is formed on the lower resist film 3. At this time, by containing silicon in the intermediate resist film 4, when the upper or lower resist film 3 and the intermediate resist film 4 are mutually etched, the upper or lower resist film 3 and the intermediate resist film 4 can be mutually etched. A difference in etching rate between the resist film 4 and the resist film 4 can be ensured.

Next, an upper resist film 5 is formed on the intermediate resist film 4. The upper resist film 5 has photosensitivity to exposure light and the like.

Next, the mask patterns 7a to 7c are transferred to the upper resist film 5 by an exposure method using the exposure mask 6 (FIG. 5(a)), and then developed to form the first resist film made of the upper resist film 5. patterns 5a to 5c are formed (see FIG. 5(b)).
)).

Next, using the first patterns 5a to 5c as a mask, the intermediate resist film 4 is etched, and the second patterns 4a to 4c made of the intermediate resist film 4 are formed on the first patterns 5a to 5c. (Figure 5(c)
).

Next, the underlying resist film 3 is selectively etched using the second patterns 4a to 4c as masks. This completes the formation of patterns 8a to 8c for etching the object to be patterned 2 (FIG. 6(d)).
.

Thereafter, the patterned object 2 is etched using the patterns 8a to 8c as masks (FIG. 6(e)
)).

0012

By the way, when forming a fine pattern, it is necessary to make the upper resist film 5 thinner in order to improve the resolution. For this reason, Fig. 7(a)
), when the intermediate resist film 4 is etched using the first patterns 5a to 5d formed from the upper resist film 5 as a mask to form second patterns 4a to 4d, the second patterns 4a to 4d are formed as shown in FIG. ), the first pattern 5
The maskability of a to 5d is not sufficiently ensured, and the second patterns 4a to 4d are not formed normally.

Therefore, in order to ensure sufficient maskability of the first patterns 5a to 5d, it is necessary to reduce the thickness of the intermediate resist film 4 as well as the thickness of the upper resist film 5. However, when the intermediate layer resist film 4 is made thinner, pinholes are generated in the intermediate layer resist film 4, which again poses a problem that it becomes difficult to form a normal pattern.

The present invention has been made in view of such conventional problems, and it is possible to reduce pinholes in the etching-resistant film even when the etching-resistant film is made thinner in order to improve patterning accuracy. The purpose of this invention is to provide a method for forming a pattern.

[0015]

[Means for Solving the Problems] The above problems, as illustrated in the principle cross-sectional view of FIG. forming a second etching-resistant film 12 on the first etching-resistant film 11 by coating at least twice; and forming a photosensitive film 1 on the second etching-resistant film 12;
3, patterning the photosensitive film 13 by an exposure method to form first patterns 13a to 13d, and etching the second etching resistance using the first patterns 13a to 13d as a mask. selectively etching the film 12 to form second patterns 12d to 12f made of the second etching-resistant film 12; and etching the first etching-resistant film using the second pattern as a mask. 11, and the second pattern 12d~
This is achieved by a pattern forming method including the step of forming third patterns 11a to 11d made of the first etching-resistant film 11 under the pattern 12f.

[0016]

[Operation] In the pattern forming method of the present invention, the first
First, a first etching-resistant film 11, a second etching-resistant film 12, and a photosensitive film 13 are sequentially formed on the object to be patterned 10, and the second etching-resistant film 12 is coated at least twice. It is formed by For example, if a resist film is used as the first etching-resistant film 11 and the photosensitive film 13, and an SOG film is used as the second etching-resistant film 12, a normal three-layer resist method structure is obtained. Then, a pattern consisting of the first etching resistant film/second etching resistant film is formed by a method similar to a normal three-layer resist method.

By the way, in order to improve the resolution, the photosensitive film is made thinner, and along with this, the second etching-resistant film 1 is
2 is made thinner, pinholes are likely to occur in each film formed by each coating, but since the second etching-resistant film 12 is formed by at least two coatings,
Each second etching-resistant film 12 formed by each application
Even if there are pinholes in the image, the possibility that the pinholes will overlap is extremely small.

As a result, the second etching-resistant film 12
Since pinholes can be reduced as a whole,
While improving the resolution, a normal first etching-resistant film 11 is formed using the second etching-resistant film 12 as a mask, and a normal film consisting of the first etching-resistant film/second etching-resistant film is formed. It is possible to form various patterns.

[0019]

[Example] Figures 2(a) to (c), Figures 3(d) to (f),
FIGS. 4(g) and 4(h) are cross-sectional views illustrating a pattern forming method using a three-layer resist method according to an embodiment of the present invention.

First, a novolak-based positive photoresist is applied by spin coating onto an Al film as a patterning target 10 on a substrate 9 whose surface is formed as an interlayer insulating film, and then heat-treated at a temperature of 200°C. By doing this, a lower resist film (first etching-resistant film) 11 having a film thickness of 2 μm is formed (FIG. 2(a)). At this time, in order to flatten the unevenness of the object to be patterned 10, the lower resist film 11 is formed quite thick, and in order to prevent reflection of exposure light etc. from the object to be patterned 10 during exposure, The lower resist film 11 contains a light absorbing material.

Next, as a mask for etching the lower resist film 11, an intermediate SOG film (second etching resistant film) 12 having a thickness of 1400 Å is formed on the lower resist film 11. At this time, in order to improve the resolution, the thickness of the intermediate layer SOG film 12 is reduced in conjunction with the thinning of the upper resist film 13.
In order to reduce pinholes in the OG film 12, SOG is applied twice by a spin coating method. That is, first, Figure 2 (
As shown in b), SOG was applied by the first spin coating method.
After coating, heat treatment was performed at a temperature of 200 °C to achieve a film thickness of 70 °C.
A lower layer SOG film 12a having a thickness of 0 Å is formed. Subsequently, as shown in Fig. 2(c), S was coated by a second spin coating method.
After applying the OG, heat treatment is performed at a temperature of 200° C. to form an upper SOG film 12b having a thickness of 700 Å. At this time, each SOG film 12a, 12b formed by each coating
Pinholes are likely to occur in S, but two coats of S
Since the OG film 12 is formed, even if pinholes are formed in the SOG films 12a and 12b formed by each coating, the possibility that the pinholes will overlap is extremely small. Therefore, almost no pinholes occur in the intermediate layer SOG film 12 as a whole.

Next, a novolac positive photoresist is applied by a spin coating method, and then heat treated at a temperature of 80° C. to form a film with a thickness of 0.3 μm on the intermediate layer SOG film 12.
A resist film (photosensitive film) 13 is formed as an upper layer of m (FIG. 3(d)). The upper resist film 13 has photosensitivity to exposure light and the like.

Next, the mask patterns 15a to 15d are formed on the upper resist film 1 by an exposure method using the exposure mask 14.
3 (FIG. 3(d)) and then developed to form first patterns 13a to 13d consisting of the upper resist film 13 (FIG. 3(e)).

Next, the first pattern 13a is etched by reactive ion etching (RIE) using CF4 gas.
~13d as a mask, the intermediate layer SOG film 12 is etched, and SOG is etched under the first patterns 13a~13d.
Second patterns 12c to 12f made of the film 12 are formed (FIG. 3(f)).

Next, ECR (Ele
ctron Cyclotron Resonance
) second patterns 12c-1 by plasma etching
Using 2f as a mask, the underlying resist film 11 is selectively etched to form third patterns 11a to 11d. At this time, since the second patterns 12c to 12f are made of SOG film and contain Si, the lower resist film 1
1. A sufficient difference in etching rate between the two can be obtained. Further, since the second patterns 12c to 12f have reduced pinholes, the maskability is more perfect. This completes the formation of normal patterns 16a to 16d for etching the object to be patterned 10 (FIG. 4(g)).

Thereafter, the patterned body 10 is selectively etched and removed using the patterns 16a to 16d as a mask to form wirings 10a to 10d (FIG. 4(h)).
).

As described above, according to the embodiment of the present invention,
Similar to the structure of the normal three-layer resist method, a lower resist film 11/an intermediate layer SOG is formed on the patterned object 10.
Film 12/upper resist film 13 were formed in sequence (see FIG. 3).
d) After that, S is applied using the same method as the normal three-layer resist method.
Patterns 16a to 16d consisting of the OG film 12 and the upper resist film 13 are formed (FIG. 4(g)).

In particular, in the case of the embodiment, the intermediate layer SOG film 1
2 is formed by applying it twice (Fig. 2(b),(c)
)) Therefore, even if the intermediate layer SOG film 12 is made thinner, which is related to improving the resolution of the upper resist film 13, the intermediate layer SOG film 12 can be made thinner by extremely reducing the possibility that pinholes overlap. Pinholes as a whole can be reduced. As a result, while improving the resolution, a normal lower resist film 11 is formed using the intermediate layer SOG film 12 as a mask, and as a result, the lower resist film 11
/Normal pattern 16a consisting of intermediate layer SOG film 12
~16d can be formed.

In the embodiment, the intermediate layer SOG film 12
Although it is formed by applying it twice, it can also be formed by applying it three times or more depending on the case.

[0030]

As described above, in the pattern forming method of the present invention, firstly, the first etching-resistant film is formed on the object to be patterned, similar to the structure of the usual three-layer resist method. After sequentially forming the second etching-resistant film and the photosensitive film, a pattern consisting of the first etching-resistant film/second etching-resistant film is formed by a method similar to a normal three-layer resist method. There is.

In particular, in the case of the present invention, since the second etching-resistant film is formed by coating at least twice,
Even when the second etching-resistant film, which is related to improving the resolution of the photosensitive film, is made thinner, the possibility of pinholes overlapping each other is extremely reduced, thereby increasing the overall pin-pointing of the second etching-resistant film. Holes can be reduced. As a result, while improving the resolution, a normal first etching-resistant film is formed using the second etching-resistant film as a mask, and the resulting structure consists of the first etching-resistant film/second etching-resistant film. A normal pattern can be formed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating the principle of the pattern forming method of the present invention.

FIG. 2 is a cross-sectional view (part 1) illustrating a pattern forming method using a three-layer resist method according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view (part 2) illustrating a pattern forming method using a three-layer resist method according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view (Part 3) illustrating a pattern forming method using a three-layer resist method according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view (part 1) illustrating a pattern forming method using a conventional three-layer resist method.

FIG. 6 is a cross-sectional view (part 2) illustrating a pattern forming method using a conventional three-layer resist method.

FIG. 7 is a sectional view illustrating problems in the conventional example.

[Explanation of symbols]

1, 9 substrate, 2, 10 object to be patterned, 2a to 2c, 10a to 10d wiring, 3 lower resist film, 3a to 3c, 11a to 11d third pattern, 4
Intermediate layer SOG film, 4a to 4c, 12a to 12d Second pattern, 5
Lower resist film, 5a-5c, 13a-13d First pattern, 6
Exposure mask, 7a-7c Mask pattern, 8a-8c, 16a-16d, 19a-19d Pattern, 11 Lower layer resist film (first etching-resistant film), 12 Intermediate layer SOG film (second etching-resistant film) 12a lower layer SOG film, 12b upper layer SOG film, 13 upper layer resist film (third etching resistant film)
, 14 exposure mask, 15a to 15d mask pattern, 17 lower layer resist film (etching resistant film), 17
a to 17d fifth pattern, 18 photosensitive SOG film, 18a lower layer photosensitive SOG film, 18b upper layer photosensitive SOG film, 18a to 18d fourth pattern.

Claims (2)

[Claims] 1. A step of forming a first etching-resistant film (10) on the object to be patterned, and forming a second etching-resistant film (11) on the first etching-resistant film (11) by coating at least twice. forming a photosensitive film (12), and forming a photosensitive film (13) on the second etching-resistant film (12);
and patterning the photosensitive film (13) by an exposure method to form first patterns (13a) to (13).
d) and the step of forming the first pattern (13a).
The second etching-resistant film (12) is selectively etched using ~(13d) as a mask to form a second pattern film (12d) made of the second etching-resistant film (12).
) to (12f), etching the first etching-resistant film (11) using the second patterns (12d) to (12f) as a mask, and etching the first etching-resistant film (11) to form the second patterns (12d) to (12f), a third pattern (11a) consisting of the first etching-resistant film (11)
(11d) A method for forming a pattern. 2. The first etching-resistant film (11)
is a resist film, and the second etching-resistant film (1
2. The pattern forming method according to claim 1, wherein 2) is an SOG film.