JPH02126264A - Pattern forming method - Google Patents

Abstract

PURPOSE:To increase the aspect ratio of resist patterns by exposing a resist by using a 1st mask and insolubilizing the exposed part, then exposing the resist by using a 2nd mask reversed from the 1st mask, and developing the resist. CONSTITUTION:The positive resist 2 is formed on a substrate 1 consisting of a semiconductor, etc., and is exposed with UV rays 40 through the mask 3 to insolubilize the exposed part 20. The resist is then irradiated with the UV rays 41 by using the mask 6 reversed from the mask 3 so that the irradiated regions 21 are made soluble in an alkaline developing soln. The resist is then developed to obtain the resist patterns 2A. A wear of the film of the resist surface is suppressed according to this method and, therefore, the patterns having the good shapes are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pattern forming method in a phosphorography process for semiconductor manufacturing or the like.

Conventional technology In patterning positive resist, the second pattern forming method uses a process of insolubilizing the exposed area after pattern exposure, and then exposing the entire surface to light and developing it.
The second exposure is usually the front exposure.

This process is illustrated using FIG.

A 1.2 μm thick film of positive T/JS (MP2400° Sibley) 2 is formed on a substrate 1 made of semiconductor, etc., and the pattern is exposed to i-line (NA 0.40) 4A through a mask 3 (
Figure 4-(a)). Next, the resist surface is treated (gas adsorption) with an amine compound γ, and heat treatment is performed on a hot plate 5 to insolubilize the exposed area 2o (FIG. 4-Φ)).

Next, the entire surface is exposed to ultraviolet rays (i-ray) 4B, and the unexposed area 2
Only part 1 was made soluble in the developer (Fig. 4-(C)), and the part 21 was further developed with an alkaline developer and became soluble in the developer.
is removed to form a negative resist film turn 2B having a width of 0.6 μm (FIG. 4-(d)).

Problems to be Solved by the Invention However, 7, the turn profile obtained in this way had a reverse chuck shape with the resist surface being thinned as shown in pattern 2B.

Here, the cause will be explained in detail using FIG. Figure 3 (&)
The light 4A exposed through the mask 3 exposes the portion of the resist 2 indicated by the broken line 100. However, the treatment with the amine compound 7 in the next step is performed from the surface, and the heat treatment diffuses the compound into the resist and insolubilizes the exposed area 20, but the compound does not diffuse sufficiently at the bottom of the resist and becomes insolubilized. Hard to get. Therefore, exposure section 2
The area surrounded by the broken line 0 will be insolubilized.

Further, the exposure amount of the light 4A requires twice as much energy as normal because it is necessary to photobleach the resist completely to the lower part.

Next, the entire surface is exposed using light 4BK, but this exposure light 4
B also enters the insolubilized area, and as shown in FIG. 3(b)'lc, the area 21 below the insolubilized area 20 is also exposed, and everything except the exposed area 20 becomes soluble.

Therefore, by the next development, a reverse tapered resist pattern 2B as shown in FIG. 3(C) is formed. Such a shape is difficult to use in an actual semiconductor process. An object of the present invention is to easily solve the problem of pattern shape deterioration caused by conventional cutting/forming methods.

Means for Solving the Problems In order to solve the conventional problems, the present invention performs the second exposure using a second mask that is an inversion of the first mask, rather than the entire surface exposure.
By pattern exposure using a mask, film thinning on the resist surface is suppressed and an ideal pattern is formed without reverse taper.

That is, the pattern forming method of the present invention includes a step of applying a resist onto a substrate, a step of exposing the resist in a pattern using a first mask, a step of insolubilizing the exposed portion of the resist, and a step of applying the resist to the first mask. The second inverted mask of
The method includes a step of exposing the resist in a pattern using a second mask, and a step of developing the resist to remove the portion exposed with the second mask.

The photoreceptor in the working positive photoresist is exposed to ultraviolet light.
Indene carboxylic acid (-COOH) is formed, but when an amine catalyst (R1R2R3N) is applied to this, a salt (-COOH) is formed.
oo-N''R1R2R3) and 1lXIi%-1
- The carboxylic acid is eliminated and becomes indene, which becomes insolubilized.

In this case, the amine catalyst treatment near the resist surface
Although insolubilization is promoted, as described above, it is difficult to be insolubilized in the substrate portion, and an inverted Taber pattern is inevitably formed in the next development.

Therefore, by exposing an inverted pattern, light can be prevented from penetrating to the bottom of the insolubilized layer that has already been formed.
A nearly vertical pattern can be formed. Further, in the present invention, since the unexposed fins of the second exposure are insolubilized, an ideal pattern without resist film loss can be formed. Furthermore, since the first exposure is only for the purpose of suppressing this film loss, it is only necessary to insolubilize only the surface with a small amount of exposure, and the exposure can be completed in a short time, thereby reducing the throughput. This forms a pattern in the second exposure, and
This is because the method differs from the conventional concept in that the second exposure plays an auxiliary role.

Embodiment FIG. 1 shows the main part of a method according to an embodiment of the present invention. A positive resist is formed on a substrate 1 such as a semiconductor, and an exposed portion 20 is formed by exposing the inside of the broken line portion to ultraviolet rays 4o through a pattern mask 3. The exposure amount at this time does not need to be completely photobleached to the bottom of the resist;
You can also use less. Furthermore, the surface was treated with amine compound 7,
Although heat treatment is applied, it is not necessary to insolubilize the lower part of the resist, and a short heat treatment is sufficient. Therefore, by this treatment, an insolubilized region 200 shown by diagonal lines is formed (, ). As mentioned above, in this process, the photoreceptor in the resist 2 is exposed to indenecarboxylic acid (-CO) by ultraviolet rays 40.
OH), which is then treated with an amine compound catalyst (R1R2R3
A salt (-Coo-N"R1R2R3) is generated by the action of N), and by heating K, the carboxylic acid is desorbed and becomes indene, forming an insolubilized region 200. Next, ultraviolet rays 41 Expose to light.

At this time, as shown in FIG. 1(b), the region 21 outside the broken line portion is photobleached, but the lower part of the insolubilized region 200 is not exposed due to the presence of the mask 6. Therefore, by removing the region 21 in the next development process, the reverse taper is not created.
A resist pattern 2A having a high aspect ratio as shown in FIG. 4(C) is formed.

Note that the first and second exposures may be performed using light of different wavelengths, and in this case, a standing wave suppressing effect also occurs, and good results can be obtained.

A specific example of the pattern forming method of the present invention will be explained using FIG.

A positive resist (MP2400 Sibley) 2 with a thickness of 1.2 μm is formed on a substrate 1 such as a semiconductor, and a mask 3 is passed through it.
Ultraviolet light (i
(line) 40 is exposed in a shorter time than before (,). Next, it is treated with amine compound γ (gas adsorption), and then heated on a hot plate 6.
The exposed area is insolubilized by heating to form an insolubilized region 200). One line 41 is exposed with an i-line stepper through the original reversal mask 6 to make the region 21 soluble in an alkaline developer (,). Paddle development was performed for 60 seconds using an alkaline developer to form a resist pattern 200. As a result, a good 0.6 of Taber around 1 which is close to vertical without film loss is obtained.
A resist pattern 2A of μm was formed (d).

The first exposure is carried out using an excimer stabilizer (NAO, 35).
This was performed using 248 nm excimer laser light.

Thereafter, a treatment experiment similar to that of the above example was conducted. As a result, a good resist butter/with a good aspect ratio of 0.4 μm of aSO was obtained.

Effects of the Invention According to the method of the present invention, it is possible to form a resist pattern in a good shape in the phosphorography process, and the throughput is also good, making industrial use possible easily and having industrial value. expensive.

[Brief explanation of drawings]

1 and 2 are process cross-sectional views of an embodiment of a pattern forming method according to the present invention, and FIGS. 3 and 4 are process cross-sectional views of a conventional pattern forming method. 1...Substrate, 2...Positive resist (MP
2400), 3... Mask, 4... Ultraviolet rays [i-ray (3SS--)), 5... Hot plate, 6... Inversion mask, Finished...Amine compound, 200...Insolubilized area, 2 people...
...Resist pattern. Name of agent Patent attorney Shigetaka Awano and 1 other person Fig.

Claims (3)

[Claims] (1) A step of applying a resist onto a substrate, a step of exposing the resist in a pattern using a first mask, a step of insolubilizing the exposed portion of the resist, and a second mask in which the first mask is reversed. selectively exposing portions of the resist not exposed by the first mask using a mask;
A pattern forming method comprising the step of developing the resist and removing the resist in the portion exposed with the second mask. (2) The pattern forming method according to claim 1, wherein the exposure using the first mask and the exposure using the second mask are performed with light of different wavelengths. (3) The pattern forming method according to claim 1, wherein the step of insolubilizing the exposed area involves adsorption of an amine compound to the resist and heating.