JPH05129251A - Resist pattern formation - Google Patents

Abstract

PURPOSE:To provide a method, which prevents bottom layer resist residue at the recessed part on a substrate without excessively overetching the bottom layer resist when the substrate has a recessed part, for pattern formation using multi-layer resist in semiconductor device production. CONSTITUTION:The bottom layer resist of multi-layer resist has poly methyl methacrylate 2 as the first layer, the film of novolak resist 3 as the second layer, and top layer resist 4 is formed on the bottom layer resist for patterning and etching.

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 using a multilayer resist in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional multilayer resist pattern forming process.

FIGS. 3A to 3E are schematic views of the steps.
In FIG. 2, 1 is a substrate to be processed, 2 is a lower layer resist, and 3 is an upper layer resist.

First, in FIG. 2 (a), a lower resist 2 having a thickness capable of covering the steps of the substrate 1 is applied onto a substrate 1 to be processed, and then a hot plate or a high temperature atmosphere is used for 200-2.
Heat at 50 ° C.

Next, as shown in FIG. 2B, an upper layer resist 3 is applied and heated on the flattened substrate to form a multilayer resist structure. After that, in FIG. 2C, the energy beam 4 is irradiated according to a desired pattern, and the upper layer resist pattern 3 is obtained by the developing process of FIG. 2D.

Finally, as shown in FIG. 2E, the lower layer resist is patterned by reactive ion etching or the like using the upper layer resist pattern 3 obtained in FIG. 2D as a mask, and the process is completed.

[0007]

However, in the steps described above, when a concave portion exists in the exposed region of the substrate after etching the lower layer resist, the lower layer resist remains inside the concave portion and a defect is generated in a later step. There was a problem that it would occur. In addition, when over-etching is performed to sufficiently etch the recesses, the dimension of resist patterning is reduced, and the surface of the substrate step upper portion exposed earlier is
Excessively sputtered and adhered to the sidewall of the resist pattern,
There is a problem that the resist cannot be removed in the subsequent resist stripping process.

As described above, according to the present invention, when the lower layer resist having a step on the substrate to be processed is patterned by reactive ion etching or the like, it is possible to form the resist in the recess on the substrate to be processed without excessive overetching. It is an object of the present invention to provide a lower layer resist structure capable of preventing the lower layer resist from remaining.

[0009]

According to the present invention, in a step of forming a resist pattern on a substrate to be processed, polymethylmethacrylate (hereinafter referred to as PMMA) is coated on the substrate to be processed, and a novolac resist is coated on the upper portion thereof. The two-layer structure is used as a lower layer resist.

[0010]

As described above, in the present invention, since the PMMA film having a high etching rate is provided on the bottom of the lower resist, excessive over-etching required for etching the concave portion of the substrate to be processed is reduced. You can As a result, the dimensional controllability of the resist pattern is improved, and it is possible to prevent a film that is difficult to peel off from being formed on the sidewall of the resist pattern due to sputtering of the substrate to be processed.

[0011]

EXAMPLE FIG. 1 shows a process of an example of the present invention, which will be described in order below.

In FIG. 1 (a), P is formed on the substrate 1 to be processed.
Spin-apply MMA2. The film thickness of PMMA is determined by the depth of the concave portion of the substrate 1 to be processed so that it can be filled. 18 after application in a hot plate or high temperature atmosphere
Heat at 0 ° C.

Next, referring to FIG. 1B, for example, HPR204
A novolak resist 3 such as that manufactured by Fuji Hunt Co., Ltd. is spin-coated at a film thickness such that the surface of the resist 3 can be completely flattened, and then 200 ° C. in a hot plate or a high temperature atmosphere.
These two layers 2 and 3 which are heated to 250 ° C. are used as a lower layer resist. Next, as shown in FIG. 1C, the upper layer resist 4 is directly spin-coated on the novolac resist 3 (FIG. 1C left view) or the intermediate film 5 is formed and then the intermediate film 5 is formed. The upper layer resist 4 is spin coated on the top surface (see FIG.
(C) Right diagram), heating is performed in a hot plate or a high temperature atmosphere, and the entire film forming process is completed.

Next, as shown in FIG. 1D, a desired pattern is obtained by a known method such as exposure, development, or etching. Thereafter, as shown in FIG. 1E, the lower layer resists 2 and 3 are patterned by oxygen-based reactive ion etching. Here, the etching progresses, and when the surface of the substrate 1 is exposed, the etching of the PMMA 2 in the concave portion on the substrate 1 to be processed is started. Oxygen 98s
ccm, nitrogen 98sccm, RF1.5KW, pressure 10
When etching is performed under the condition of mTorr, the etching rate of the novolac resist (eg, HPR204) 3 is 10,000 Å / min, whereas the etching rate of PMMA2 is 18500 Å / min, which is about 1.9 times larger. Therefore, while etching the concave portion of the substrate 1 on which the PMMA 2 is formed, the film reduction and the size reduction mainly occurring in the mask pattern made of the novolac resist 3 are caused when only the resist 3 is used as the lower layer resist. Can be further reduced. Further, when the substrate 1 to be processed is subsequently subjected to etching, if conditions with strong anisotropy are used, good processing can be performed with a mask pattern having a novolac resist having strong etching resistance on the upper part thereof.

[0015]

As described above, according to the present invention,
Since the PMMA film having a high etching rate is provided on the bottom of the lower resist layer, it is possible to reduce the excessive over-etching required for etching the recesses of the substrate to be processed. As a result, the dimensional controllability of the resist pattern is improved, and it is possible to prevent a film that is difficult to peel off from being formed on the sidewall of the resist pattern due to sputtering of the substrate to be processed.

[Brief description of drawings]

FIG. 1 Example of the present invention

FIG. 2 Conventional example

[Explanation of symbols]

 1 substrate 2 PMMA 3 novolac resist 4 upper layer resist 5 intermediate film

Claims (1)

[Claims] 1. A method of forming a multi-layered resist pattern in the manufacture of a semiconductor device, the step of depositing polymethylmethacrylate as a first layer of a lower layer resist on a semiconductor substrate, and novolak as a second layer of the lower layer resist. A step of forming a resist, a step of applying and patterning an upper layer resist that serves as a mask of the lower layer resist, and a step of etching the first and second layers of the lower layer resist by oxygen-based reactive ion etching A resist pattern forming method comprising: