JPS63144520A - Pattern formation - Google Patents

Abstract

PURPOSE:To facilitate the fine pattern formation while improving the throughput by a method wherein two kinds of resists with different characteristics are laminated with each other complementing the mutual defects to form resist patterns with specific shape and characteristics. CONSTITUTION:A silicon substrate 1 is coated with PMMA 2 e.g. 0.8mum thick to be baked. Then, the PMMA layer 2 is coated with RE 5000 P 3 as novolak base electron beam resist,e.g., 0.2 mum thick to be baked. First, the RE 5000 P layer 3 is written with electron beams 4. Second, the layer 3 is developed with organic alkali exclusive for RE 5000 P to form the first patterns in line width not exceeding 0.2mum. Then, the layer 3 is subjected to RIE by oxygen to remove degenerated layers 5. Third, when overall surface is irradiated with far ultraviolet rays 6, the upper and lower layer resists are exposed. Finally, when the upper and lower layer resists are developed with xylene, uncoated region with RE 5000 P on PMMA as the lower layer resist only is melted away to transfer the upper resist patterns to the lower layer resist.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for forming a resist pattern used in the manufacture of semiconductor elements, optical application parts, and X-ray masks, and in particular, a method for forming a resist pattern using the beam foot 7 method. Regarding the method.

<Conventional technology> In recent years, semiconductor devices such as microwave devices have become highly integrated,
With miniaturization, in the field of phosphorography, 0.1 to 0.2
It is necessary to form ultra-fine patterns on the order of micrometers. However, when the pattern size becomes this small, pattern formation using conventional light becomes difficult, and phosphorography using high-energy beams such as electron beams and X-rays has been developed. In particular, electron beam exposure technology has progressed in the development of exposure equipment, and its functions have been improved to the point where it can actually be used in production, such as optical mask production, pattern formation by direct seeding, and X-ray masks. Polymethyl methacrylate (hereinafter referred to as PMMA) is used as a positive resist for such electron beam exposure technology, but this resist lacks the dry etching resistance and heat resistance required for the pattern formation process, and has low sensitivity. There was a problem that throughput was poor.

, Against this background, the conventionally used
・A resist has been developed that incorporates a functional group sensitive to electron beams into the novolac skeleton of a novolac-based resist. This resist has PMMA in terms of heat resistance required in post-processing.
Furthermore, the resistance to plasma dry etching by fluorine carbide gas of RE5000P (manufactured by Hitachi Chemical), which is a type of novolak electron beam exposure resist, is more than twice that of PMMA, which is sufficient for practical use. Furthermore, the electron beam sensitivity varies depending on the exposed area of PMMA.
The throughput is also 10 to 100 times higher.

<Problems to be Solved by the Invention> The resist film thickness required for a general semiconductor pattern forming process is at least 0.5 μm, but a resist for lift-off requires a thickness of 1 μm or more. However, with RE5000P, which is the above-mentioned 7-borac type electron beam exposure resist, a line pattern of only 0.4 to 0.5 μm can be formed even with a very thin film thickness of 0.5 μm. , 1 to 0.2 μm. This is the above RE500
The upper part of the 0P opening expands laterally during development, and after development,
This is because the overhang shape (Fig. 2 (a)) shown in conventionally used electron beam resists does not occur, but the shape where the upper part of the opening widens (Fig. 2 (b)). Another problem is that even though RE5000P is superior to PMMA in dry etching resistance, heat resistance, and sensitivity, it is inferior to PMMA in resolution.

Means for Solving the Problems> The present invention was made to solve the above problems, and consists of forming a resist with excellent resolution to a desired thickness on a substrate, and applying a dry etching resistant film on this resist. The present invention provides a pattern forming method in which a two-layer resist pattern is formed by forming a thin resist having excellent properties, heat resistance, and sensitivity.

Effect> By laminating two types of resists having different characteristics as described above, it is possible to compensate for each other's defects and form a resist pattern having a desired shape and characteristics.

In addition, the upper layer of the resist can be made thinner, making it easier to form fine patterns.
This makes it possible to significantly improve throughput.

<Example> An example of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to the following example.

FIGS. 1(a) to 1(d) are cross-sectional views showing the steps of this embodiment. That is, as shown in FIG. 1(a), PMMA 2 is coated on a silicon substrate 1 to a thickness of 0.8 μm by spin coating, and baked at 140° C. for 20 minutes.

RE5000P3, which is a novolac-based electron beam resist, is applied onto the PMMA layer 2 by a spin coating method.
It is applied to a thickness of 2 μm and baked at 90° C. for 30 minutes. Next, drawing is performed on the RE5000P layer 3 using an electron beam 4. This is a spot beam type EB lithography machine with a stain flow value of 100 PA.

Beam diameter 0.05 μm and electron beam dose 0.2 nc/
This will be done under the conditions of the tsuba.

Next, when development is performed with an organic alkali exclusively used for RE5000P, only the electron beam irradiated portion of the RE5000P layer 3 forming the upper resist layer is melted, and a first pattern having a line width of 0.2 μm or less is formed. However, as shown in FIG. 1(b), due to electron beam irradiation, the PMMA layer 2 and RE5000
A degraded layer 5 is formed between the P layer 3 and the PMMA layer 2 forming the lower resist layer, which cannot be patterned. Therefore, the pattern of the RE5000P layer 3 and the altered layer 5 thus obtained are subjected to oxygen RIE to remove the altered layer 5. This RIE uses a parallel plate type etching device and outputs io
ow.

Oxygen flow rate 40 Seem under 0,5 Torr 7
Do it for seconds. The thickness of the altered layer 5 to be removed is 100~
300A, and even if RIE is performed to remove it, the upper resist pattern consisting of the RE5000P layer 3 will not be damaged.

Next, when the entire surface is irradiated with far ultraviolet rays 6 as shown in FIG. 1(c), the RE5 of the upper resist pattern and the lower resist pattern is
000P uncovered areas are exposed. When development is then carried out with xylene, only the RE5000P non-covered region of PMMA, which is the lower layer resist, is eluted and the upper layer resist pattern is transferred to the lower layer resist, as shown in FIG. 1(d).

When the two-layer resist pattern thus obtained was observed with a scanning electron microscope, the RE5000P layer at the opening was 0.
Leave the line width at 2 μm, and use PMM as the lower layer resist.
Depending on the development time, layer A 2 dissolves beyond the opening formed by the upper resist pattern, and an overhang shape advantageous for the chit-off process is obtained.

For comparison with the above example, 0.5
The RE5000P coated with a film thickness of μm was subjected to electron beam exposure at the same current value and beam diameter as in the above example, and at the optimum electron beam dose (0.6 n C/cm ),
When development was carried out using a developer for RE5000P, a pattern of 0.2 μm as in the example was not obtained for the openings, and the line width was 0.4 to 0.5 μm. RE5000 that forms the resist
Although an electron beam was used to spot-expose the P layer 3, the present invention is not limited to this, and X-rays or the like may be used as long as it is a high-energy beam.

In the above embodiment, the PMMA layer 2 forming the lower resist layer
Although far ultraviolet rays were used for exposure, the present invention is not limited thereto, and similar effects can be obtained using electron beams or X-rays.

In the present invention, a two-layer resist method was adopted because a resist film thickness of 1 μm in width is required in pattern forming processes such as lift-off, but the same purpose cannot be achieved even if the resist has three or more layers. It will be done. but,
For example, the use of the conventional three-layer resist method having an isolated layer as an intermediate layer is disadvantageous because the process becomes complicated. Well, with the assumption that novolac-based electron beam exposure resist would be used as the upper layer, we selected various resists for the lower layer, and as a result, only PMMA did not mix with the novolak-based resist during coating and was able to form two layers well. Furthermore, it was discovered that if xylene was used as a developer, the novolak resist could be developed without damaging it, and a two-layer resist method was adopted.

<Effects of the Invention> According to the present invention, the throughput during electron beam exposure and the resolution of a novolak electron beam exposure resist with excellent dry etching resistance can be simultaneously improved, and a complicated formation process is not required for this purpose. Therefore, formation of fine patterns becomes easy. In particular, the present invention is suitable for manufacturing highly integrated semiconductor devices, optical application components, and X-ray masks.
It has high industrial value.

[Brief Description of the Drawings] Figures 1 (a) to (d) are cross-sectional views showing the steps of an embodiment of the present invention, and Figures 2 (a) and (b) show two types of resist pattern shapes. FIG. 1. Silicon substrate; 2. PMMA layer, 3. R.E.
sooop layer, 4. electron beam, 5. Altered layer 6.
Far Ultraviolet Agent Patent Attorney Takeshi Sugiyama (and 1 other person) No. 12
1

Claims (1)

[Claims] 1. When forming a resist pattern by patterning a two-layer resist formed on a substrate, an electron beam or
A pattern forming method characterized by using a resist that is sensitive to a high-energy beam such as a line and has dry etching resistance, and using a resist having development characteristics different from those of the upper layer resist as a lower layer.