JPS6066432A - Forming method of fine pattern - Google Patents

Abstract

PURPOSE:To obtain a flattened fine pattern by providing a process, etc. in which a thin-film on a resist pattern is removed through a lift-off method in a solvent capable of dissolving an organic high molecular material film. CONSTITUTION:An organic high molecular material film 22 as a lower layer is applied on a substrate 1 and an organic metallic negative type resist 23 as an upper layer, beams, electron rays or X-rays are projected in a pattern shape, and a resist pattern is formed through development. The organic high molecular material film 22 is patterned by using oxygen gas plasma etching while employing the resist pattern as a mask. The upper section of the pattern of the film 22 is coated with a thin-film 3 consisting of a metal, a semiconductor or a dielectric through evaporation, etc., and a pattern of the thin-film is obtained through a lift-off method by using a solvent for the organic high molecular material film. When the pattern of the thin-film is flattened, the organic high molecular material film 22 is patterned, the substrate is patterned through plasma etching, an etched depth section is coated with the thin-film, and the thin-film pattern is formed through the lift-off method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming a fine pattern using a negative resist by a lift-off method.

[Prior art]

First, FIG. 1 shows a conventional method for forming fine patterns using a lift-off method. That is, FIG. 1 is a process diagram of the conventional lift-off method. In FIG. 1, reference numeral 1 indicates a substrate, 21
3 is a resist, 3 is a metal, semiconductor or dielectric thin film, (a
) is a sample with resist coated on the substrate, (b) is exposed,
Resist pattern with overhang structure after development,
(C) Pattern after thin film coating and (C) Pattern after lift-off.

In the lift-off method, a metal, semiconductor, or dielectric thin film is deposited on a resist pattern, and the thin film on the resist is removed together with the resist using a solvent, so the resist used must be soluble in the solvent. For this reason, positive type resists are mostly used. However, although negative exposure is sometimes desired depending on the shape of the pattern, ordinary negative resists cannot be used for lift-off processing because the resist polymer is crosslinked by high-energy rays and becomes insoluble in solvents. Also, when using a positive resist, in order to improve the yield of 7-to-7 processing, see Figure 1 (1).
) As shown in J, it is necessary to make the resist cross-section vertical or inversely tapered (overhang structure), and the resist cross-sectional shape must be accurately controlled by exposure and development conditions, and the required exposure amount is also large. I have no choice but to do it.

On the other hand, lift-off processing has recently been used in combination with dry etching to completely planarize a processed substrate. This will be explained with reference to FIG. That is, FIG. 2 is a process diagram of conventional planarization. Reference numerals 1 to 5 in FIG. 2 have the same meanings as in FIG.
1) J shows the resist pattern after exposure and development, (C) shows the pattern after etching the substrate, (d) shows the pattern after thin film coating, and (θ) shows the pattern after beam 7 to 7. As shown in Figure 2, in the conventional planarization process, the substrate is dry-etched to a certain depth, and then a different type of material is lifted on to that depth to planarize the substrate. With the miniaturization of element dimensions, the difficulties of lamination lithography on stepped substrates can be solved all at once.

However, it has sufficient resistance to dry etching,
Moreover, a suitable resist that can be used as a mask for subsequent lift-off processing has not been developed.

In this case, controlling the cross-sectional shape of the resist is much more difficult than in simple lift-off processing.

[Purpose of the invention]

The present invention was made in order to solve the problems of the prior art, and its purpose is to flatten the substrate by using the negative resist type 7-to-7 process and the beam 7-to-7 process. The object of the present invention is to provide a method for forming fine patterns.

[Structure of the invention]

To summarize the present invention, the first invention of the present invention is an invention of a fine pattern forming method, which includes the step of providing an organic polymer material film layer on a substrate to be processed, and applying a negative resist containing an organic metal on top of the film layer. a step of exposing the negative resist in a pattern using light, electron beams or X-rays, and then developing the organic polymer material by oxygen gas plasma etching using the developed negative resist pattern as a mask; The process of patterning the film layer, ``The process of coating the entire surface with a thin film of metal, semiconductor, or dielectric material by vapor deposition or sputtering, and lifting off the thin film on the resist pattern in a solvent that can dissolve the organic polymer material film. It is characterized in that it includes each step of removing by a method.

The second invention of the present invention includes the step of patterning the organic polymer material film layer of the first invention, and coating the entire surface with a thin film of metal, semiconductor, or derivative by vapor deposition or sputtering. The method is characterized in that a step of plasma etching the substrate to be processed is inserted using the pattern obtained in the patterning step as a mask.

The basic processing process of the present invention is shown in FIG. That is, FIG. 3 is a process diagram of forming fine turns according to the present invention. In FIG.
indicates a thin film of metal, semiconductor or dielectric. First, an organic polymer material film is applied as a lower layer on a substrate, and an organic metal negative resist is applied as an upper layer (FIG. 3a).

Next, a resist pattern is formed by irradiating light, electron beams, or X-rays in a pattern and developing it (FIG. 6b).

Using this resist pattern as a mask, a patterned polymer material film is patterned using oxygen gas plasma etching (FIG. 5C). After coating this pattern with a thin film of metal, semiconductor, or dielectric material by vapor deposition or sputtering (Fig. 5 d), a thin film pattern is obtained by using a solvent for an organic polymer material film by the 7-to-7 method ( Figure 3 θ). When planarizing, the organic polymer material film was patterned (Fig. 3 c').
After that, the substrate is further plasma etched to form a pattern (Fig. 3 f), and the etched depth is coated with the thin film (Fig. 3 g). A thin film pattern is formed by lift-off method (Fig. 6 g). h).

As the above-mentioned organic metal-containing negative resist,
An organic silicon-based, organic aluminum-based, organic germanium-based, or organic tin-based polymer material can be used. In particular, general-purpose silicone resins among organic silicon-based polymer materials are known to act as negative resists, and can be easily applied to the process of the present invention. In addition, since the lower layer uses a polymeric material that is soluble in a solvent, when the organometallic resist is coated on the lower polymeric material and further developed, the coating solvent and developing solvent are selected so that the lower polymeric material does not dissolve. Therefore, such a two-layer material must be selected. In this respect, silicone resin-based negative resists are particularly effective in the process of the present invention since they have excellent solubility.

The overhang structure in the present invention will be explained with reference to FIGS. 4 and 5. FIG. 4 is a schematic cross-sectional view of a pattern immediately after just etching, and FIG. 5 is a schematic cross-sectional view of a pattern in which an overhang structure has become noticeable due to overetching. Code 1.22.25 in each figure
is synonymous with Fig. 5. The overhang structure effective in the lift-off method can be controlled as shown in FIGS. 4 and 5 by changing the etching conditions of oxygen gas plasma etching, regardless of the exposure and development conditions of the upper resist layer.

As explained above, the present invention has the following advantages.

(1) Organic metal negative resists have high resistance to oxygen gas plasma etching, so the resist film can be thin and have high resolution.

(2) The overhang structure that is effective in the lift-off method can be controlled by changing the etching conditions of oxygen gas plasma etching.

(3) The upper layer negative resist is exposed to light, electron beam or
Although the resist polymer is cross-linked by the radiation and becomes insoluble in the solvent, the lower organic polymeric material film is soluble, so it is possible to process a negative pattern.

〔Example〕

The present invention will be explained in more detail below using Examples, but the present invention is not limited thereto.

Example 1 A phenyl methacrylate and methacrylic acid copolymer was applied to a thickness of 0.6 μm on a silicon substrate (surface thermally oxidized) and prebaked. Furthermore, a silicone-based negative resist (sensitivity of about 80 μC/at?) was coated on this to a thickness of 0.15 μm. A 20 KV electron beam was applied to this resist for 0.4μ.
Irradiation was performed over a length of 0.5 steps at a pitch of m. The irradiated edges were immersed in a mixed solvent of diimbutylketone-cyclohexane (*:1) for 20 seconds, developed, and then rinsed in cyclohexane for 20 seconds to obtain a 0.5.0 resist pattern with a line width of about 2 μm and 1 long. Oxygen reactive ion etching using the resist pattern as a mask (oxygen flow rate 50 acay,
Pressure 10 millitorr, power α1W/cm”) is 3/8
When this was carried out for 0 seconds, a resist pattern with a line width of 0.2 μm and a lower ffi film pattern with a line width of 01 μm were formed therebeneath, resulting in an Oparts 1 ring structure. At this time, the resist film thickness was approximately 0.14 μm. After depositing about 0.3 μm of gold on this pattern, irradiating it with ultrasonic waves in methyl ethyl ketone for 5 minutes and lifting it on, the line width was 0.2 μF.
++% A fine gold pattern with a height of about 03 μm and a length of 0.5 cm was obtained.

Example 2 After applying an organic polymer material film and a resist in the same manner as in Example 1, a 0.5 μm square area was irradiated with a 20 KV electron beam, developed and rinsed in the same manner as in Example 1, resulting in an isolated resist of approximately 15 μm square. A film (turns were obtained). When etching was performed with oxygen for 8 minutes and 30 seconds under the same conditions as in Example 1, a 4 μm square lower layer film (turns) were obtained under the O, S μm square resist film turns. Next, after depositing silicon oxide (810) to a thickness of 0.4 μm, irradiation with ultrasonic waves in methyl ethyl ketone for 5 minutes and lift-off resulted in a surface of approximately 0.5 μm square and 0.4 μm deep.
A window was created.

Example 3 A phenyl methacrylate and methacrylic acid copolymer was applied to a thickness of 5 μm on a silicon substrate coated with a thermal oxide film (0.2 μm thick), and prebaked. A silicone-based negative resist (sensitivity: 40 μO/l:w') was applied onto this to a thickness of 0.2 μm.

This resist was irradiated with a 20 KV electron beam over a length of 0.5 m at a pitch of 0.5 μm. Development, rinsing, and oxygen plasma etching were carried out in the same manner as in Example 1.
When the process was carried out for minutes and 30 seconds, a resist pattern with a line width of 0.25 μm and a lower layer pattern with a line width of 0.2 μm were obtained. Using this as a mask, reactive ion etching was performed with OF4 + H2 (20%) gas (flow rate 20 AAA, pressure 60 mTorr, power a 2 W/cm") for 8 minutes.
A silicon oxide film pattern with a depth of 0.2 tlm and a line width of 125 μm was obtained. Gold was evaporated to a thickness of 0.2 μm on top of this, and when lift-off was performed in the same manner as in Example 1, the line width [1L]
A flattened gold pattern of 25 μm and 0.2 μm thickness was obtained.

〔Effect of the invention〕

As explained in detail above, according to the method of the present invention, a system composed of an organic metal negative resist and an organic polymer material film can be used to form fine patterns on the submicron order, flatten the patterns, and moreover, it is difficult to achieve conventional methods. Because it is possible to lift off negative patterns such as isolated patterns,
It has the advantage that it can be used for VLSI element processing, which requires miniaturization.

[Brief explanation of drawings]

Figure 1 is a process diagram of the conventional lift-off method, Figure 2 is a process diagram of conventional planarization, Figure 5 is a process diagram of fine pattern formation according to the present invention, and Figure 4 is a cross section of the pattern immediately after just etching. FIG. 5 is a schematic cross-sectional view of a pattern in which an overhang structure is noticeable due to overetching. 1: Substrate, 21 Resist, 22: Organic polymer material film, 23: Organometallic negative resist, 5: Thin film of metal, semiconductor or derivative Patent applicant: Nippon Telegraph Corporation Agent Hirotoshi Nakamoto Akira Inoue ~2/ D8 Figure 1 Figure 2 ~23 22 Go to 22

Claims (1)

[Claims] 1. A step of providing an organic polymer material film layer on a substrate to be processed, a step of providing an organic metal-containing negative resist on top of the layer, and a step of applying the negative resist using light, electron beams or X-rays. a step of patterning the organic polymer material film layer by oxygen gas plasma etching using the developed negative resist butter as a mask; The method includes the steps of coating the entire surface of the body with a thin film by vapor deposition or sputtering, and removing the thin film on the resist pattern by a 7-off method in a solvent that can dissolve the organic polymer material film. A fine pattern formation method using Hanzheng. 2. The fine pattern forming method according to claim 1, wherein the organic metal-containing negative resist is a silicone-based negative resist. (v) The step of providing an organic polymer material film layer on the substrate to be processed, the step of providing an organic metal-containing negative resist on top of the layer, and after exposing the negative resist in a pattern using light, electron beams, or X-rays. , a step of developing, a step of patterning the organic polymer material film layer by oxygen gas plasma etching using the developed negative resist pattern as a mask, and a step of plasma etching the substrate to be processed using the pattern thus obtained as a mask. A step of coating the entire surface with a thin film of metal, semiconductor or dielectric material by vapor deposition or sputtering, and a step of coating the thin film on the resist pattern in a solvent capable of dissolving the organic polymer material film by a 7-to-7 method. A fine pattern forming method characterized by including each step of a removing step. 4. The fine pattern forming method according to claim 3, wherein the organic metal-containing negative resist is a silicone-based negative resist.