JP2000035678A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain metallic patterns having high accuracy and high reliability by forming mask patterns for a lift-off of an eaves structure by a process of preventing the contact of a substrate surface with water or aq. soln. on the substrate having high ruggedness. SOLUTION: The laminated patterns 3 of the eaves structure are obtd. by executing patterning by the process of preventing the contact of the substrate surface with the water or the aq. soln. after successively depositing a lower layer resist 2 and an upper layer resist 4 on the substrate 1 having the large ruggedness. After a sputter film 5 is deposited thereon, the laminated resist patterns are removed as the mask patterns for lift-off by lift-off, by which the high-accuracy metallic patterns are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pattern forming method using a lift-off process.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a metal pattern on a substrate, a metal is formed on the entire surface of the substrate, a desired pattern is formed by a photoresist, and etching is performed using the mask as a mask. A method of removing the photoresist with an organic solvent or the like has been used. Etching methods are roughly classified into a wet etching method using various chemicals and a dry etching method using plasma. However, these chemicals used for wet etching are often acidic or alkaline aqueous solutions. It is difficult to completely remove the chemical after the etching is completed on a substrate having an uneven surface such as a glass ceramic substrate.

[0003] For this reason, there is a problem that these chemicals remaining in the concave portion corrode the metal wiring and vaporize the aqueous solution in a subsequent heating step, thereby damaging the insulating layer formed on the metal pattern. there were. Further, in the etching of the laminated metal, a different chemical solution is used for each metal, so that a step such as cleaning is required for each etching, and the process is complicated. For this reason,
A photoresist serving as an etching mask is required to have resistance to various chemicals such as acids and alkalis, and there is a problem that options are reduced.

[0004] Further, when a treatment such as hard baking is performed in order to enhance chemical resistance, it may be difficult to remove the resist later. Further, when the dry etching method is used, it is difficult to etch the metal in the concave portion of the substrate and the etching residue is apt to occur, so that it is necessary to lengthen the etching time and the like, and the processing accuracy is lowered. there were.

In order to solve such a problem, there is a pattern forming method using a lift-off process of forming a metal pattern after forming a pattern of a desired shape using a photoresist, and finally removing the photoresist. Japanese Patent Application Laid-Open Nos. 3-21011 and 6-77106 disclose related techniques. However, in these methods, a single-layer resist is patterned into a reverse taper shape according to process conditions as a lift-off mask material.

However, on a substrate having large unevenness, light at the time of exposure largely reflects on the surface of the substrate, and it is difficult to accurately form a reverse tapered pattern. Further, in order to prevent the film from wrapping around during film formation, the film forming apparatus and conditions are often restricted. Furthermore, in the case where the lift-off mask material used is an alkali developing type photoresist, since a developing solution containing an alkaline aqueous solution as a main component is used, problems such as corrosion of wiring cannot be solved as in the case of forming a metal pattern by wet etching. Had a problem.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and is excellent in pattern accuracy on a substrate having unevenness and capable of reducing corrosion and damage. An object of the present invention is to provide a method for forming a metal pattern by a lift-off process.

[0008]

Means for Solving the Problems The present inventors have studied various methods for forming a lift-off mask pattern on an uneven substrate, and formed a mask pattern having an eaves structure without using water or an aqueous solution. It has been found that processing accuracy and reliability are greatly improved.

The results of specific experimental studies will be described below.

First, the following three methods can be used to form a lift-off mask pattern having an eaves structure using an organic resin having a two-layer structure.

(1) A process of sequentially patterning a mask material on a substrate.

(2) A process of sequentially laminating a mask material on a substrate and then sequentially patterning from the upper layer.

(3) A process of sequentially laminating a mask material on a substrate and subsequently patterning the mask material from the upper layer.

(1) A method of coating or laminating a lower organic resin layer on a substrate by coating or laminating,
Next, the upper organic resin layer is formed and patterned by a method such as coating or laminating. Therefore, to pattern each layer separately,
The organic resin layer is desirably a photoresist, but the mode may be liquid or film. Furthermore, since the surface of the substrate is exposed to a developing solution or a rinsing solution in any of the upper and lower layer patterning, it is desirable not to use an aqueous developing solution or a rinsing solution in order to reduce damage to wiring and the like. Therefore, it was found that in this process, it is necessary to perform patterning with an organic solvent using a solvent-developable photoresist for both the upper layer and the lower layer.

It has also been found that, depending on the combination of the photoresist in the upper and lower layers, the pattern of the already developed lower layer swells or dissolves during the development of the upper layer, thereby deteriorating the eaves shape and lowering the pattern accuracy. For this reason, when developing the upper layer, it is necessary to take care that the pattern of the lower layer is not damaged. Specifically, there is a method such as a post-bake treatment of the lower layer pattern.

The process (2) is a process in which the upper and lower organic resin layers are laminated and formed by a method such as coating or laminating, and then patterned sequentially from the upper layer. In this process, the upper layer pattern can be used as an etching mask at the time of lower layer patterning. For this reason, the upper layer is desirably a photoresist, but the lower layer may be an organic resin having no photosensitivity. When patterning the upper layer, the surface of the substrate is covered with the lower layer, so that the developing solution or the rinsing liquid does not directly touch the surface of the substrate. Therefore, it was found that any photoresist could be used. Specific examples include an alkali development type photoresist and a solvent development type photoresist, and the form may be liquid or film.

On the other hand, when patterning the lower layer, the surface of the substrate is exposed by development or etching, so that an aqueous developing solution, rinsing solution or etching solution cannot be used. Therefore, a method of patterning with a developer containing an organic solvent as a main component using a photoresist of a solvent development type, a method of performing wet etching with an organic solvent using an upper photoresist as an etching mask, or a method of performing upper photoresist There is a method in which dry etching is performed using as an etching mask.

As a specific method of forming a pattern by dry etching, ashing, sputter etching,
Methods such as reactive ion etching and ion milling can be used. However, during the development and wet etching of the lower layer, it is necessary to perform a process such as post-baking so that the pattern of the upper layer is not damaged such as swelling and dissolution.In the case of dry etching, the organic resin of the upper layer and the organic layer of the lower layer are required. It has been found that it is necessary to optimize the film thickness in consideration of the etching selectivity of the resin.

The point (3) is exactly the same as the step (2) in that the upper and lower organic resin layers are laminated by a method such as coating or laminating, but the patterning of the upper layer and the lower layer is performed continuously. There is a characteristic. This process is
It was confirmed that the upper layer pattern can be used as an etching mask at the time of lower layer patterning as in the process (2). For this reason, it has been found that the upper layer is desirably a photoresist, but the lower layer may be an organic resin having no photosensitivity. However, since the patterning of the upper layer and the lower layer is performed continuously, it is necessary that the lower layer can be developed or etched with a developer used for patterning the upper layer.

Since the surface of the substrate is exposed to a developing solution or a rinsing solution, it is desirable not to use an aqueous developing solution or a rinsing solution in order to reduce damage to wiring and the like. For this reason, it is desirable to use a solvent-developing type photoresist for the upper layer and pattern it with a developing solution containing an organic solvent as a main component.

On the other hand, since the lower layer can be etched with a developer used for patterning the upper layer and the eaves shape can be formed with high precision, no particular photosensitivity is required. No organic matter is acceptable.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, representative embodiments of the present invention will be described.

A first embodiment of the present invention will be described with reference to FIG.

First, a glass ceramic was used as the substrate 1 shown in FIG.

Next, as shown in FIG. 1B, an OM manufactured by Tokyo Ohka Co., Ltd.
R-83 was applied and baked to form a film having a thickness of about 3 microns. The baking condition is 90 ° C / 30 in a clean oven.
Minutes.

Next, exposure is performed with a projection exposure machine.
After developing for 30 seconds using a solvent developer SL (manufactured by Tokyo Ohka), 30 minutes using a solvent rinse solution for OMR (manufactured by Tokyo Ohka).
Rinsed for seconds. Further, post-baking was performed after rinsing to obtain a lower resist pattern 3-1 shown in FIG. Post-baking conditions are 140 ° C / 30 in a clean oven.
Minutes.

Next, as shown in FIG. 2D, BMR manufactured by Tokyo Ohka Co., Ltd. was applied and baked as an upper layer resist 4 to form a film having a thickness of about 10 μm. The baking condition was 90 ° C./30 minutes in a clean oven.

Next, the film was exposed with a projection exposure machine, developed with a solvent developer SK-4 (manufactured by Tokyo Ohka) for 2 minutes, and then rinsed with a solvent rinse solution SA (manufactured by Tokyo Ohka) for 1 minute. Further, post-baking was performed after rinsing to form an upper resist pattern 3-2, thereby obtaining an eave-shaped laminated pattern 3 shown in FIG. Post-baking conditions were 140 ° C./30 minutes in a clean oven.

Next, as shown in FIG. 1F, a Ni film 5 was formed to a thickness of about 2 μm by RF sputtering.

Lastly, the eave-shaped laminated resist pattern 3 was immersed in a resist stripper S502A (manufactured by Tokyo Ohka) at 110 ° C. for 10 minutes to obtain a Ni pattern 5 as shown in FIG.

The pattern accuracy of the metal pattern formed by the above method was as follows. In a 150-micron width portion, the variation in the shift amount from the mask dimension was 1.8 microns at 3σ, where σ was the standard deviation. In addition, the use of this method has also enabled a significant reduction in defects such as metal corrosion and damage to the insulating film.

A second embodiment of the present invention will be described with reference to FIG.

First, a glass ceramic was used as the substrate 1 shown in FIG.

Next, as shown in FIG.
As a lower resist 2 on the surface 1-1 to be processed
MR-83 was applied and baked to form a film having a thickness of about 3 microns. The baking condition is 90 ° C / 3 in a clean oven.
0 minutes.

Next, as shown in FIG. 2C, HN-920 made by Hitachi Chemical Co., Ltd. was thermocompressed as the upper layer resist 4 to obtain a laminated resist 2. The pressure bonding of the upper resist 4 was performed by heating the substrate 1 on which the lower resist 2-1 had been formed in advance to 60 ° C. and laminating the substrate 1 at a roll temperature of 110 ° C.

Next, the upper resist 4 was exposed by a projection exposure machine, developed with a 0.7% aqueous sodium carbonate solution for 35 seconds, and then rinsed with pure water for 1 minute. Further, post-baking was performed after rinsing to obtain an upper resist pattern 3-2 shown in FIG. Post-baking conditions were 140 ° C./30 minutes in a clean oven.

Next, the lower resist 2 is exposed by a projection exposure machine, developed with a solvent developer SL (manufactured by Tokyo Ohka) for 30 seconds, and then rinsed with a solvent rinse solution for OMR (manufactured by Tokyo Ohka) for 30 seconds. did. Further, post-baking was performed after rinsing to form a lower resist pattern 3-1 to obtain an eave-shaped laminated pattern 3 shown in FIG.
Post bake conditions: 140 ° C / 3 in a clean oven
0 minutes.

Next, as shown in FIG. 2F, a Ni—W alloy film 5 was formed to a thickness of about 2 μm by RF sputtering. Finally, the eave-shaped laminated resist pattern 3 was immersed in a resist stripper S502A (manufactured by Tokyo Ohka) at 110 ° C. for 10 minutes to obtain a Ni—W alloy pattern 5 as shown in FIG.

The pattern accuracy of the metal pattern formed by the above method was as follows: in a 150-micron width portion, the variation in the shift amount from the mask dimension was 1.2 microns at 3σ, where σ was the standard deviation. In addition, the use of this method has also enabled a significant reduction in defects such as metal corrosion and damage to the insulating film.

A third embodiment of the present invention will be described with reference to FIG.

First, a glass ceramic was used as the substrate 1 shown in FIG.

Next, as shown in FIG.
Was coated and baked as a lower-layer resist 2 to a thickness of about 3 microns. The baking condition is 140 in a clean oven.
° C / 30 minutes.

Next, as shown in FIG. 3C, HN-920 manufactured by Hitachi Chemical was laminated as the upper resist 4.
The lamination of the upper resist 4 was performed under the conditions of a preheat of 60 ° C. and a roll temperature of 110 ° C.

Next, the upper resist 4 was exposed by a projection exposure machine, developed with a 0.7% aqueous sodium carbonate solution for 35 seconds, and then rinsed with pure water for 1 minute. Further, post-baking was performed after rinsing to obtain an upper resist pattern 3-2 shown in FIG. Post-baking conditions were 140 ° C./30 minutes in a clean oven.

Next, the lower resist 2 is dry-etched by reactive ion etching of oxygen using the upper resist pattern 3-2 as a mask to form a lower resist pattern 3-1, and the eave shape shown in FIG. Was obtained. The plasma etching conditions were as follows: gas pressure 26.8 Pa, gas flow rate 20 sccm, R
The F power was 200 W.

Then, a nickel film 5 was formed to a thickness of about 2 μm by RF sputtering as shown in FIG.

Finally, the eaves-shaped laminated resist pattern 3 was immersed in a resist stripper S502A (manufactured by Tokyo Ohka) at 110 ° C. for 10 minutes to obtain a nickel pattern 5 as shown in FIG.

The pattern accuracy of the metal pattern formed by the above-mentioned method was 1.5 microns at 3 σ with a standard deviation of σ when the standard deviation was σ in a 150 μm wide portion. In addition, the use of this method has also enabled a significant reduction in defects such as metal corrosion and damage to the insulating film.

A fourth embodiment of the present invention will be described with reference to FIG.

First, a glass ceramic was used as the substrate 1 shown in FIG.

Next, as shown in FIG. 2B, a Z-Zone made by Nippon Zeon Co., Ltd.
PN2070 was applied and baked to form a film having a thickness of about 3 microns. The baking conditions are 90 ° C /
30 minutes.

Next, as shown in FIG. 3C, OMR-83 manufactured by Tokyo Ohka Co. was applied as an upper layer resist 4 and baked to form a film having a thickness of about 8 μm. The baking conditions were 90 ° C./30 minutes in a clean oven.

Next, the upper resist 4 was exposed by a projection exposure machine and developed for 1 minute using a solvent developer SL (manufactured by Tokyo Ohka), and at the same time, the lower resist 2 was wet-etched. Further, rinsing was performed for 30 seconds using a solvent rinsing solution for OMR (manufactured by Tokyo Ohka), and then post-baking was performed to obtain a lamination pattern 3 having an eaves shape shown in FIG. Post-baking conditions were 140 ° C./30 minutes in a clean oven.

Next, as shown in FIG. 3E, a Ni-W alloy film 5 was formed to a thickness of about 2 μm by RF sputtering. Finally, the eave-shaped laminated resist pattern 3 was immersed in a resist stripper S502A (manufactured by Tokyo Ohka) at 110 ° C. for 10 minutes to obtain a Ni—W alloy pattern 5 as shown in FIG.

The pattern accuracy of the metal pattern formed by the above-described method was as follows: in a 150-micron width portion, the variation in the shift amount from the mask dimension was 2.5 microns at 3σ where σ was the standard deviation. In addition, the use of this method has also enabled a significant reduction in defects such as metal corrosion and damage to the insulating film.

As a comparative example, an alkali-developed photoresist was patterned into an inversely tapered shape and examined. The wraparound during metal film formation was large, and the pattern accuracy of the obtained metal pattern was 150 μm. In the above, the variation of the shift amount from the mask dimension was 9.3 to 16.2 microns in 3σ where σ was the standard deviation.

[0057]

As described above, according to the present invention, a metal pattern with higher precision can be formed on a substrate having irregularities than a conventional lift-off mask pattern. Further, by using a process in which water or an aqueous solution does not come into contact with the substrate surface during patterning, it is possible to reduce the rate of occurrence of defects after wiring formation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining each step of a method of forming a pattern on a substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the order of each step by a pattern forming method on a substrate according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating the order of steps in a pattern forming method on a substrate according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating the order of steps in a pattern forming method on a substrate according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1-1 ... Work surface, 2 ... Lower layer resist, 3 ... Eave-shaped lamination pattern, 3-1
... lower layer resist pattern, 3-2 ... upper layer resist pattern, 4 ... upper layer resist, 5 ... metal film (pattern).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Maria Kazuki 1 Horiyamashita, Hadano-shi, Kanagawa Prefecture Hitachi Computer Co., Ltd. General-purpose Computer Division (72) Inventor Toshiro Terouchi 1- 1 Horiyamashita, Hadano-shi, Kanagawa F-term in the General Purpose Computer Division of Hitachi, Ltd. (reference) 2H096 AA30 CA12 CA16 DA01 GA03 GA08 GA17 HA01 HA23 HA28 JA04 KA02 LA02

Claims (7)

[Claims] 1. A pattern forming method, comprising: a step of patterning an eaves-shaped lift-off mask material on a substrate having an uneven surface; a step of forming a metal thin film; and a step of lifting off the mask material. 2. The pattern forming method according to claim 1, wherein said eave-shaped lift-off mask material is formed of a two-layer organic resin pattern. 3. The pattern forming method according to claim 2, wherein the patterning method of the organic resin pattern having the two-layer structure is a forming process using neither water nor an aqueous solution for both the upper layer and the lower layer. 4. The pattern forming method according to claim 3, wherein the forming process not using water or an aqueous solution is a process using an organic solvent. 5. The pattern forming method according to claim 3, wherein the patterning method of the lower layer of the organic resin pattern having the two-layer structure is a forming process not using water or an aqueous solution. 6. The pattern forming method according to claim 3, wherein a patterning method of a lower layer of the organic resin pattern having the two-layer structure is a dry etching method. 7. A pattern forming method according to claim 1, wherein a step of forming a thin film according to claim 1 uses a sputtering method.