JPH036651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a lift-off resist stencil using a photoresist film.

Prior Art and Problems to be Solved by the Invention With the increasing integration of electronic devices, precise lift-off technology has become required for electrode formation and electrode wiring. Refer to lift-off technology 1a-1
First, as shown in FIG. 1a, a resin layer 2 is formed on a base material, for example, a semiconductor wafer 1. Next, by etching the resin layer 2 into a desired pattern shape, the reference No. 1
A resist stencil for lift-off as shown in Fig. b is obtained. A metal layer 3 is deposited on the resist stencil by vapor deposition or sputtering as shown in FIG. 1c. Next, when the resin layer 3 is removed using a solvent or the like,
As shown in Reference FIG. 1d, metal wiring is formed on a semiconductor wafer. The reliability of lift-off depends on the quality of Slencil formation.

The stencil formation methods used so far are
It is roughly divided into the following four methods. These are (1) double resist method, (2) metal film/resist composite film method, (3) spacer method, and (4) single coating method. Methods (1) to (3) are
In both cases, two different types of films are superimposed, and an overhang-shaped stencil is obtained by individually etching the films.

An overhang stencil refers to a stencil having the cross section shown in FIG. Usually, metal vapor deposition does not occur as shown in the schematic diagram shown in reference FIG. 1c, but also occurs on the etched side surface 4 of the resin layer 2.
By simply removing the resin layer 2, complete wiring as shown in FIG. 1d cannot be formed. On the other hand, when the stencil is formed in an overhanging shape, metal vapor deposition is not performed on the etched side surfaces of the resin layer 2, and ideal wiring can be obtained. Therefore, the stencils produced by methods (1) to (3) are of good quality, but on the other hand, they require the production of two types of films and two different etching processes, which complicate the process and cause major problems. It has drawbacks.

As indicated in the name, method (4) improves the drawbacks of (1) to (3) in that a single coating film can be used. However, with method (4), it is difficult to form an overhanging resist stencil. Therefore, generally, after coating the resist, the resist film is brought into contact with a specific solvent (for example, chlorobenzene) to make only the surface layer hardly soluble in the phenomenon liquid, thereby forming an overhang-shaped resist film. However, this method requires immersion in a solvent for a long time to achieve the desired effect, and furthermore, the process is complicated because it is a wet process.

OBJECTS OF THE INVENTION The present invention provides a method for easily manufacturing overhang resist stencils by a single coat method.

Structure of the Invention The present invention involves coating a substrate with a positive photoresist consisting of a cresol novolac resin and an ester of naphthoquinonediazide sulfonic acid to form a photoresist film, and exposing the film to a bromine-containing gas before or after exposure. Provided is a method for producing a resist stencil characterized by contact.

In the present invention, it has been discovered that a positive resist film composed of a cresol novolac resin and an ester of naphthochitone diazidophonic acid has the property of causing a strong reaction to bromine gas and easily becoming poorly soluble in a developer.

Representative examples of the base material used in the present invention include semiconductor wafers, such as silicon, gallium arsenide, indium phosphide, and the like wafers. Various types of base materials can be used depending on the purpose of use, and the base material is not limited to the above examples.

The present invention uses a positive photoresist comprising a cresol novolac resin and an ester of naphthoquinonediazide sulfonic acid. This resist contains a photodegradable photosensitive agent that becomes soluble in the developing solution upon exposure, and a positive image can be obtained by printing from a positive film. As such a resist, for example, AZ-1350 manufactured by Shipley is commercially available. The photoresist is applied to the substrate by conventional methods, such as brushing, spin coating, and the like.

The above-mentioned photoresist film is exposed using a positive film, and is contacted with a bromine-containing gas before or after exposure. Examples of the bromine-containing gas include inert gas diluted bromine gas and vaporized methanol gas. Preferably, it is vaporized methanol gas. The bromine concentration of the bromine-containing gas, the contact time, and the flow rate of the bromine-containing gas vary as appropriate depending on the use of the resulting resist stencil, the length l of the eaves, and the like. For example, when AZ-1350 manufactured by Shipley Co., Ltd. is applied to a thickness of 1.5 μm, if a bromine/methyl alcohol mixture is used at a nitrogen gas flow rate of 100 c.c./min, the bromine gas will be removed in a short time of 40 to 50 seconds. After contact, a phenomenon is carried out for 2 minutes using a phenomenon liquid (MF-314 manufactured by Shipley) to obtain an eave of 0.4 μm.

The base material that has been in contact with bromine gas may be exposed to light if necessary.
The exposed portions of the resist layer are washed away with a solvent. On the other hand, the unexposed areas remain uncleaned and a resist stencil is obtained. In particular, in the present invention, due to the action of bromine, the surface layer portion of the non-exposed portion is sufficiently solidified and made difficult to dissolve, and an excellent stencil with no disturbance in the end shape can be obtained.

The present invention will be explained in detail with reference to the drawings. FIG. 1 shows a schematic cross-sectional view of a resist stencil obtained by the method of the present invention. FIG. 2 shows a schematic diagram of the apparatus used in the method of the invention.

In FIG. 2, 1 represents a nitrogen gas cylinder, and nitrogen gas is introduced into a bromine/methyl alcohol mixture 5 in a glass bubbler 4, and this pressure is applied to a semiconductor sample 7 coated with resist on a sample holder 6.
sends bromine-containing gas to. The flow rate of nitrogen gas is regulated by a flow controller 2. 3 represents a gas flow switching point. Using the above apparatus, a sample coated with Shipley's AZ-1350 to a thickness of 1.5 μm was exposed to nitrogen gas at 100 c.c./min and 50 c.c./min before exposure. Developer MF-
314 and 1/3 water by volume at 21℃.
FIG. 3 shows the relationship between the length l of the eaves and the bromine contact time when developing for a minute. The same results were obtained even if the film was exposed to bromine after exposure.

Effects of the Invention According to the manufacturing method of the present invention, a resist stencil with sufficient eaves can be obtained in a short time and in a drying process, thereby simplifying the process and making manufacturing extremely easy.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of an overhang resist stencil. Figure 1 shows the eaves of the resist stencil, which is formed through some kind of chemical reaction because it is poorly soluble in a resist developer; indicates a region that is soluble in a resist developer without passing through, and l indicates the length of the eaves of the overhang resist stencil. FIG. 2 is a schematic diagram of the apparatus used to create the resist stencil of the present invention.
1 is nitrogen gas cylinder, 2 is flow rate control, 3
4 indicates a gas flow switching pot, 4 indicates a glass bubbler, 5 indicates a bromine/methyl alcohol mixture, 6 indicates a sample holder, and 7 indicates a semiconductor sample coated with resist. Further, FIG. 3 is a diagram showing the relationship between the exposure time to bromine and the length l of the eaves of the formed resist stencil in an example of the present invention.

Claims (1)

[Scope of Claims] 1. A positive photoresist consisting of a cresol novolac resin and an ester of naphthoquinonediazide sulfonic acid is applied onto a substrate to form a photoresist film, and a bromine-containing gas is applied to the film before or after exposure. A method for producing a resist stencil, the method comprising contacting with a resist stencil. 2. The manufacturing method according to item 1, wherein the bromine-containing gas is diluted bromine gas or vaporized methanol bromine gas.