JPS62165651A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To form a resist pattern with a simple stage by coating an intermediate layer which prevents property deterioration between an upper layer resist and lower layer resist and can be developed together with the upper layer resist in the lower layer resist. CONSTITUTION:A PMMA which is a deep UV resist is coated as the lower layer resist 2 on a substrate 1 and the intermediate layer 11 which prevents the property deterioration between the upper layer resist 3 and the lower layer resist 2 and can be developed together with the upper layer resist 3 is coated thereon. A UV resist which is the upper layer resist 3 is then coated. AUV resist which is the upper layer resist 3 is exposed and developed, by which said resist is patterned. The intermediate layer 11 is also stripped at the same instant. The lower layer resist 2 is then exposed with the upper layer resist 3 as a mask. The upper layer resist 3 is removed and at the same time, the intermediate layer 11 is removed as well; finally the lower layer resist 2 is etched.

Description

Detailed Description of the Invention "Industrial Application Field" This invention relates to multilayer resist technology in light exposure technology, which is the mainstay of LSI production, and in particular to a method for separating upper and lower resist layers in this multilayer resist technology. It is related to.

"Conventional technology" As integrated circuits become faster and more highly integrated, there is an increasing demand for finer patterns to be formed on substrates. Processing technology: When performing photoetching, the original image is directly projected onto the wafer in a reduced size and exposed.The X-Y moving stage on which the wafer is placed is moved in small increments, and the positioning is performed using an automatic focusing mechanism and a computer. The technology of printing the same pattern over and over again) is reaching its limits.

In other words, ∎ There are limits to the optical system in obtaining high resolution, ∎ The flatness of the pattern deteriorates due to step differences and it becomes impossible to focus, ∎ Also, light interferes within the resist due to reflection from the substrate surface. , pattern edges are no longer sharp, etc., and the resolution of single-layer resist technology is 1μ.
The limit was about m.

As a solution to the above-mentioned problem, the steps of the base pattern on the substrate are flattened and the focus is adjusted.

Attempts to reduce substrate reflectance. Multilayer resist techniques have been proposed.

Figure 2 shows PCM (portable resist technology), which is the most famous two-layer resist technology, which is a type of multi-layer resist technology.
This figure shows the conformal mask process.

An overview of the PCM process will be described below. In this process, a r)eep UV (g external light) resist is used as the lower resist layer, and a UV resist is laminated on the two-layer resist.

That is, as shown in FIG. 2(a), 1. First, PMMA (polymethyl methacrylate), which is a DeCp TJV resist, is applied on a substrate 1 as lower layer resists 1 and 2, and a tJV resist is applied thereon as an upper layer resist 3.

Next, as shown in FIG. 2(b), the upper layer of UV resist 3
A pattern edge is created by exposing and developing.

Then, as shown in FIG. 2(c), the lower resist 2 made of PMMA is exposed all at once using the upper UV resist 3 as a mask, and then developed as shown in FIG. 2(d).

The above is an overview of the PCM process, and according to this,
A degraded layer 4 is formed between the upper layer and the lower layer due to the influence of the solvent, etc., and this becomes a residue 5 during development. This phenomenon is called an interlayer, and when developing the lower resist 2 made of PMMA, it is necessary to separate the upper resist 3 and the lower resist 2 by some means in order to impair the uniformity of the development.

Therefore, according to the three-layer resist technique, 5OG (spin-on glass) is used as an intermediate separation layer between the upper resist layer 3 and the lower resist layer 2 to prevent the above-mentioned interlayer. A three-layer structure resist process using this SOG as an intermediate layer is called a TLR process.

To give an overview of the above TLR process, first see Figure 3 (
As shown in a), De is first deposited on the substrate as the lower resist 2.
After applying PMMA, which is an ep UV resist, and applying 5OG6, a UV resist as an upper layer resist 3 is applied thereon.

Next, as shown in FIG. 3(b), the upper layer resist 3
Pattern edges are created by exposing and developing the resist.

Then, as shown in FIG. 3(o), the TJV of the upper layer resist 1-
Using the resist 3 as a mask, the lower resist 2 made of PMMA is exposed. and 5 as shown in Figure 3(d).
The OG 6 is etched, the tJV resist 1-3 is removed as shown in FIG. 3(A), and the lower resist 2 is etched.

"Problems to be Solved by the Invention" The above is an overview of the TLR process, and although interlayers that occur in the PCM process can be prevented by this means of interlayer separation, as mentioned above, the process is complicated. There was a drawback that it could be stored away.

The purpose of this invention is to solve the above-mentioned drawbacks of the conventional example.
It is an object of the present invention to provide an interlayer separation method between multilayer resists that is simple in terms of process.

"Means for Solving the Problems" That is, the present invention is a resist pattern forming method comprising the following steps.

b) Deeρ as a lower resist (2) on the substrate (1)
A certain PMMA is applied to the UV resist 1, and thereon an intermediate layer (11) that prevents deterioration between the upper resist (3) and the lower resist h (2) and can be developed together with the upper resist (3). After coating, UV resist 1- is further coated as an upper layer resist (3).

(Example) Next, the TJV resist, which is the upper resist (3), is exposed and developed to pattern it. At the same time, the intermediate layer (11) is also peeled off.

c) Then, the lower resist (2) is exposed using the upper resist (3) as a mask.

2) Remove the upper resist layer (3). At the same time, the intermediate layer (11) is also removed.

e) Finally, the lower resist layer (2) is etched.

The lower layer resist (2) is preferably a Deep UV resist, and P M
M A, PMG T (poly [dimet
hyl glut, arimjde]) can be used. Ordinary novolak photoresists can also be used.

In addition, as the upper layer resist (3), various photoresists such as novolac type, styrene type, etc. can be used, but because the lower layer resist (2) is exposed using this upper layer resist (3) as a mask, it is difficult to resist UV irradiation. The condition for use is that it becomes opaque upon exposure to light.

As the intermediate layer (11), any material can be used as long as it prevents deterioration between the upper resist (3) and the lower resist (2) and can be developed together with the upper resist (3). This intermediate layer (11) includes a lower resist (2).
) is useful for preventing deterioration between PMMA suitable as the upper layer resist (3) and a UV resist suitable as the upper layer resist (3).
Polyvinyl alcohol can be particularly preferably used as a material that can be developed together with the upper resist (3) made of V resist.

"action" Next, the operation of the present invention will be explained.

As mentioned above, the upper resist layer (3) is used as the intermediate layer (11).
), we used an intermediate layer (II) that could be developed with this intermediate 7! The process of specially treating only (11) becomes unnecessary.

Therefore, the present invention does not require consideration of the upper resist layer (3), which was necessary in the process of treating the intermediate layer (11).

"Example" The present invention will be explained in detail below based on examples.

FIG. 1 is a process diagram showing an embodiment of the resist pattern forming method according to the present invention.

In FIG. 1, reference numeral 1 indicates a substrate on which a resist pattern is formed, which has been cleaned with pure water or the like. Next, as the lower resist 2, 1) deep UV resist such as PMMA is spin-coated to a thickness of 2 μm, and heat treated at 180° C. for 2 minutes.

On top of the lower resist 2 after processing, there is also an intermediate layer that prevents deterioration between the upper resist 3 and the lower resist 2 and can be developed together with the upper resists 1 to 3! j11
is spin coated to a thickness of 0.3 μm. As such an intermediate layer 11, polyvinyl alcohol or a modified resin thereof is suitable. The reason is as follows.

(1) Reaction between the upper resist layer 3 and the lower resist layer 1-2 can be prevented. Therefore, no altered layer is generated between the upper resist layer 3 and the lower resist layer 2.

・It is good to layer ■ and - without 7 in each of resists 1-3 and lower resists 1-2. Therefore, delamination and uneven coating do not occur.

An upper resist 3 is spin-coated on the intermediate layer 11 to a thickness of 1 μm, and prebaked at 90° C. for 1 minute. As this upper layer resist 3, various photoresists such as novolac type, styrene type, etc. can be used, but the lower layer resist 2 can be replaced with this upper layer resist 3.
Since it is exposed as a mask, it is a condition for its use that it becomes opaque upon exposure to UV irradiation.

Next, this upper resist layer 3 is aligned with a photomask and exposed to ultraviolet light, and then developed and rinsed with a solvent to perform patterning. At the time of this development, the intermediate layer 11 is also peeled off at the same time, and the above-mentioned interlayer is not generated. Of course, the patterning at this time depends on whether the upper layer resist 3 is positive type or not.
It depends on whether it is a negative type.

Then, using the patterned upper resist 3 as a mask, the lower resist 2 is exposed to deep UV light.

After that, the upper resist layer 3 is removed. At the same time, the intermediate layer 11 is also removed, similar to the time of development.

Finally, the lower resist 2 is etched. Of course, post-baking is required if necessary.

"Effects of the Invention" As described above, in the resist pattern forming method of the present invention, between the upper resist 3 and the lower resist 2,
Since the interlayer 11 is interposed to prevent deterioration in quality and can be developed together with the upper resist 3, it dissolves in the solvent when the upper resist 3 is developed. Therefore, the etching step of the intermediate separation layer in the conventional interlayer separation method is unnecessary, and a resist pattern can be formed through a simple process.

Further, in the present invention, since the etching step of the intermediate layer 11 is not necessary as described above, there is no accompanying adverse effect on the resist pattern, etc. Furthermore, the resist pattern can have excellent resolution, and the resist pattern can be made finer.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a process diagram showing an example of the resist pattern forming method of the present invention, and FIGS. 2 and 3 are process diagrams showing an example of the conventional resist pattern forming method. be.

Claims (1)

[Claims] 1. A resist pattern forming method comprising the following steps. b) A lower resist (2) is coated on the substrate (1), which prevents deterioration between the upper resist (3) and the lower resist (2), and which can be developed together with the upper resist (3). After applying the intermediate layer (11), the upper resist layer (3) is further applied thereon. b) Next, the upper resist layer (3) is exposed and developed to pattern it. At the same time, the middle class (11
) is also peeled off. c) Then, the lower resist (2) is exposed using the upper resist (3) as a mask. d) Remove the upper resist layer (3). At the same time, the intermediate layer (11) is also removed. e) Finally, the lower resist layer (2) is etched. 2. The method for forming a resist pattern according to claim 1, wherein the intermediate layer (11) is made of polyvinyl alcohol.