JPH08220770A - Formation of resist pattern and formation of metallic pattern - Google Patents

Abstract

PURPOSE: To provide a method for forming resist patterns and method for forming metallic patterns for the purpose of obtaining metallic films which have no hook-shaped projections to be the cause for degradation in device characteristics, such as noise generation, at the ends of the metallic films to be formed on a base material and have extremely smooth surfaces. CONSTITUTION: A polyamide acid coating film 2 is previously formed as a pretreatment on the base material 1 and a photoresist 3 of a butadiene system is applied and formed thereon. The resist 3 is then irradiated thereon with active rays via a photomask 4 and thereafter the development processing and the etching of the polyamide acid coating film of the lower layer are executed, by which the resist patterns are formed. Further, the metallic film 5 is formed by sputtering on the base material surface exposed by etching of the polyamide acid coating film 2. The resist 3 and polyamide acid coating film 2 remaining on the base material 1 are then peeled away by a liquid chemical, by which the metallic patterns are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method and a metal pattern forming method using the obtained resist pattern.

[0002]

2. Description of the Related Art A photoresist material has been conventionally used in the formation of a semiconductor device or a device using a vacuum film forming process. However, as a commonly used resist material, a reversal type The metal pattern obtained is an inverted pattern.

As shown in FIG. 3, such a conventional method is such that a photoresist is formed on a substrate, exposed and developed, and then a metal layer is formed by a method such as sputtering. As shown in c), erosion is observed at the interface between the substrate surface and the photoresist. Therefore, if sputtering is performed in this state, the metal atoms wrap around this eroded part due to the semi-isotropic nature of the metal, so 1000 Å
When the metal pattern having the above thickness is formed, hook-shaped protrusions as shown in FIG.

If such hook-shaped projections are formed on the metal pattern, it may lead to deterioration of device characteristics such as generation of noise, which is not preferable.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resist pattern for forming a metal pattern without hook-shaped protrusions formed by the above-mentioned conventional method.

Another object of the present invention is to provide a metal pattern having a smooth surface using the resist pattern obtained as described above.

[0007]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, prior to forming a photoresist on the surface of a base material, a polyamic acid coating film was previously prepared as a pretreatment. It was found that a metal pattern having a smooth surface without hook-shaped projections can be obtained by forming it, and the present invention has been completed.

That is, the method of forming a resist pattern of the present invention is characterized by including the following steps (a) to (d). (A) a step of applying a polyamic acid solution on a substrate and drying it to form a polyamic acid coating film, (b) a step of applying a photoresist on the formed coating film, (c) a photo through a photomask After irradiating the resist with actinic rays, it is developed to form a desired resist pattern, and (d) a step of etching only the polyamic acid coating film exposed by the alkaline chemical solution.

In addition to the steps (a) to (d), the metal pattern forming method of the present invention further includes the following (e) to (e).
It is characterized by including the step (f). (E) A step of forming a metal layer on the surface of the base material exposed by etching the polyamic acid coating film by sputtering, and (f) a step of sequentially peeling off the resist and the polyamic acid coating film remaining on the base material with a chemical solution.

The resist pattern forming method and the metal pattern forming method of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows an example of a resist pattern forming method and a metal pattern forming method of the present invention. FIGS. 1 (a) to 1 (d) show the resist pattern forming method of the present invention, and FIG. 7A to 7F are process drawings for explaining the method for forming a metal pattern of the present invention.

In the method of forming a resist pattern of the present invention, first, as a first step, a polyamic acid solution is applied onto a base material such as an AlTiC (aluminum oxide / titanium carbon) substrate and dried to 0.2 ~ 1 μm
A polyamic acid coating film having a certain thickness is formed (Fig. 1
(See (a)). In the polyamic acid solution used in this step, a wavelength of an actinic ray (for example, a compound (photosensitizer) that absorbs 300 to 450 nm) such as 4- (2′-nitro) for irradiating a photoresist formed in a later step is used. Phenyl) -2,6-dimethyl-3,5-dicarbomethoxy-1,4-dihydropyridine and the like may be contained in any amount.

As the polyamic acid used in the present invention, the tetracarboxylic acid unit and the diamine unit in the structural unit of the polyamic acid are benzene, biphenyl, triphenyl, terphenyl, toluene, xylene, tolidine, naphthalene, biphenyl ether, Examples include so-called all-aromatic compounds having a tetravalent aromatic group and a divalent aromatic group such as biphenyl sulfone, biphenyl propane, biphenyl hexafluoropropane, and benzophenone. Of these aromatic groups,
From the viewpoint of the film removal property (the dissolution rate in the film removal solution is high), benzene is preferred as the tetravalent aromatic group and biphenyl ether is preferred as the divalent aromatic group.

As a solvent (reaction solvent) for preparing these polyamic acid solutions, for example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, dimethylformamide, hexamethylphosphoramide are used. And the like, and these solvents can be used alone or in combination of two or more.

Next, a photoresist is applied on the polyamic acid coating film formed by the above process (see FIG. 1 (b)). The thickness to be applied can be set arbitrarily,
From the viewpoint of resolution and the like, it is usually 0.5 to 2 μm, preferably 1 to 1.5 μm. The photoresist used in this step is not particularly limited as long as it can form a pattern with the developer used in the developing step described later. As a preferable photoresist, non-polar one can be used so as not to mix with the lower polyamic acid. Specifically, a butadiene-based resist material or the like can be used. Particularly preferred butadiene-based photoresist materials include OMR-83 and OMR-85, trade names, manufactured by Tokyo Ohka.

Next, an actinic ray is irradiated from above the photoresist formed above through a photomask. If you want to obtain a negative pattern by the development process, develop only with a developer that dissolves only the photoresist in the unirradiated area and does not dissolve the photoresist in the irradiated area and the lower polyamic acid coating film, such as hexane. A resist pattern having a desired shape can be obtained (see FIG. 1 (c)).

Finally, only the exposed polyamic acid coating film is treated with an alkaline chemical solution, for example, an inorganic alkali aqueous solution such as sodium hydroxide aqueous solution or potassium hydroxide aqueous solution, or an organic alkaline aqueous solution such as tetramethylammonium hydroxide aqueous solution or acetylcholine aqueous solution, Alternatively, the resist pattern of the present invention can be obtained by etching with a mixed solution of these and alcohol (see FIG. 1D).

On the other hand, in the method for forming a metal pattern of the present invention, a metal layer is formed on the resist pattern obtained above by a sputtering method (see FIG. 1 (e)). That is, the metal layer is formed on the surface of the base material exposed by the etching in the step (d). The metal layer to be formed is preferably made of copper, tungsten or silicon, and is usually 500 to 3000 Å, preferably 10
It is formed with a thickness of about 00 to 2000Å.

After the formation of the metal layer, the photoresist layer and the polyamic acid coating film remaining on the substrate can be sequentially peeled off with a chemical solution to form the metal pattern of the present invention (see FIG. 1 (f)). As the chemicals used in this step, in addition to the alkaline chemicals exemplified in the etching step (step in FIG. 1D), these chemicals and N-methyl-2 are used.
-Pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide and the like can be used as a mixed liquid with a high boiling point organic solvent. Among these, as a preferable chemical solution, a tetramethylammonium hydroxide aqueous solution or
N-methyl-2-pyrrolidone is mentioned.

[0020]

In the resist pattern forming method and the metal pattern forming method of the present invention, since the polyamic acid coating film is previously formed on the surface of the base material and the photoresist is formed thereon, the lower surface of the photoresist is formed. There is no etching around the edges. Therefore, the metal pattern finally obtained does not have hook-shaped projections formed at the ends thereof as in the conventional case, and does not cause deterioration of device characteristics such as noise generation.

[0021]

EXAMPLES Examples of the present invention will be shown below and described in more detail. However, the present invention is not limited to these examples, and various modifications can be made without departing from the technical idea of the present invention. Can be modified and applied.

EXAMPLE 1 Pyromellitic dianhydride and 4,4'-diaminodiphenyl ether were mixed in N-methyl-2-pyrrolidone in approximately equimolar amounts (so that the concentration of polyamic acid is about 10% by weight). Was added) and reacted at room temperature with stirring to obtain a polyamic acid solution.

Then, this solution was formed into a film on a 4-inch silicon wafer using a spin coater, and dried on a pot plate at 80 ° C. for 15 minutes to form a polyamic acid coating film having a thickness of about 2 μm.

Next, a photoresist (manufactured by Tokyo Ohka Co., Ltd., trade name OMR-83) was formed on the above polyamide coating film by a spin coater, and the film was formed on a hot plate at 115 ° C. for 2 minutes.
It was dried for 0 minutes to form a photoresist layer having a thickness of about 2 μm.

After that, light irradiation was performed for 2 seconds with a high pressure mercury lamp (10 mW / cm ² ) through a photomask. After completion of irradiation, spray development is carried out for 1 minute with the above photoresist-dedicated developer (Tokyo Ohka Co., Ltd., trade name OMR developer SG), and 1 with a dedicated rinse solution (Tokyo Ohka Co., Ltd., trade name OMR rinse solution). After performing a rinsing process for a minute, post baking was performed on a hot plate at 160 ° C. for 20 minutes to form a negative pattern having a desired shape on the silicon substrate. The resolution at this time was about 2 μm in the independent line width.

Using the obtained negative pattern as a mask, 3
The exposed polyamic acid coating of the lower layer is etched by a dip method using a wt% tetramethylammonium hydroxide aqueous solution, and then, where the polyamic acid coating is slightly side-etched inside the pattern from the photoresist layer edge, continue to wash with water. , Dried.

As a result, it was possible to obtain a resist pattern of the present invention in which the polyamic acid coating film was side-etched by about 0.5 μm from the end of the photoresist layer toward the inside of the pattern.

Example 2 A base vacuum degree of 1 × 10 was applied on the resist pattern obtained in Example 1 using a high frequency high rate sputtering device (trade name SMH-2306RE) manufactured by Nippon Vacuum Technology Co., Ltd.
E-6 torr, vacuum degree during processing 2 × 10E-3 torr
r, argon gas introduction amount 30 SCCM, processing power RF3
Copper was sputter deposited under the conditions of 50 W and a treatment time of about 6 minutes to obtain a copper film of about 1000 Å. Observation of this cross section revealed a copper film having the form shown in FIG.

Next, a 10% by weight tetramethylammonium hydroxide aqueous solution / N-methyl-2-pyrrolidone (1
/ 1 volume ratio mixture)
For 10 minutes, the photoresist layer and the polyamic acid coating film were dissolved and peeled off, and the copper film formed on the photoresist layer was also peeled off.

As a result, a silicon wafer on which only the copper sputtered film pattern was left was obtained. The edge portion of the obtained copper film had no hook-shaped protrusions and had a smooth surface. In addition, in the step of dissolution and peeling with the peeling chemical, when the ultrasonic waves were used in addition to the above-mentioned conditions, the peeling treatment time could be reduced to about half.

Example 3 Instead of pyromellitic dianhydride in Example 1,
Instead of the 3 wt% tetramethylammonium hydroxide aqueous solution used for etching the polyamic acid coating film by the dipping method using biphenyltetracarboxylic dianhydride, a 10 wt% tetramethylammonium hydroxide aqueous solution / isopropyl alcohol ( 1/1
A resist pattern of the present invention could be obtained by the same method as in Example 1 except that a volume ratio mixed solution) was used.

As a result of performing this resist pattern in the same manner as in Example 2, as in Example 2, a copper sputtered film pattern could be obtained on the silicon wafer.
The edge portion of this copper film had no hook-shaped projections and had a smooth surface.

Example 4 In the polyamic acid solution used in Example 1, 5 parts by weight of 1,4-parts by weight per 100 parts by weight of polyamic acid solids were added.
A resist pattern of the present invention was formed in the same manner as in Example 1 except that dihydropyridine was added. Further, using this pattern, copper was sputtered in the same manner as in Example 2, and as a result, a copper film pattern having a smooth surface without hook-shaped protrusions at the edge portion of the copper film could be obtained as in Example 2. .

Comparative Example 1 A resist pattern was formed in the same manner as in Example 1 except that naphthoquinone diazide and phenol novolac resin were used instead of the photoresist used in Example 1, and then Example 2 and The same copper sputtering was performed.

As a result, the edges of the formed copper film were raised (that is, boat-shaped projections were formed on the edges), and it was not possible to obtain a copper film pattern having a smooth surface as in the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of each step for explaining a resist pattern forming method and a metal pattern forming method of the present invention.

FIG. 2 is an enlarged sectional view of FIG.

FIG. 3 is a cross-sectional view of each step for explaining a conventional resist pattern forming method and metal pattern forming method.

FIG. 4 is an enlarged sectional view of FIG.

[Explanation of symbols]

 1 Base Material 2 Polyamic Acid Coating 3 Photoresist 4 Photomask 5 Metal Layer 6 Hook-like Protrusion

Claims (6)

[Claims] 1. A method for forming a resist pattern, which comprises the following steps (a) to (d): (A) a step of applying a polyamic acid solution on a substrate and drying it to form a polyamic acid coating film, (b) a step of applying a photoresist on the formed coating film, (c) a photo through a photomask After irradiating the resist with actinic rays, it is developed to form a desired resist pattern, and (d) a step of etching only the polyamic acid coating film exposed by the alkaline chemical solution. 2. The method of forming a resist pattern according to claim 1, wherein the photoresist is a butadiene-based resist material. 3. The resist pattern forming method according to claim 1, wherein the pattern is a negative pattern. 4. A method for forming a metal pattern, which further comprises steps (e) to (f) in addition to the steps (a) to (d) described in claim 1. (E) A step of forming a metal layer on the substrate surface exposed by etching of the polyamic acid coating film by sputtering, and (f) A step of sequentially peeling off the resist and the polyamic acid coating film remaining on the substrate with a chemical solution. 5. The method of forming a metal pattern according to claim 4, wherein the metal layer is formed of copper, tungsten or silicon. 6. The method for forming a metal pattern according to claim 4, wherein the chemical solution is a mixed solution of an alkaline aqueous solution and a high boiling point organic solvent.