JPS62193127A - Formation of metallic pattern - Google Patents

Abstract

PURPOSE:To make it possible to use resist, which is hard to be deformed and peeled, by providing a process for forming a metal film on a substrate including the resist, and providing a process for applying plasma etching, removing the resist and removing the metal film on the resist by lift-off. CONSTITUTION:Resist 12 is applied on a GaAs substrate 11, on which an N<+> layer 10 is formed. Thereafter, ultraviolet rays are applied through a photomask 13 with a line having a width of 4mum being made to remain, and the resist is exposed. Then the device is rinsed and undergoes post-baking. Thus the pattern of the resist 12 is formed. Thereafter with the resist 12 as a mask, a metal film 15 is formed. Plasma etching using oxygen gas is performed, and the resist 12 is removed. Metallic patterns 14 and 15 are made to remain on the substrate 11. When lift-off is performed, a substrate 23 is set on a substrate holding stage 24. Air in a bell jar 16 is sucked through an exhausting pipe 17 and oxygen gas is supplied. A high frequency electric field is formed between electrodes 18 and 18, and oxygen plasma is yielded. Thus, the resist, which is hard to be deformed and peeled with etching liquid, can be used, and the pattern accuracy of the formed metal film is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Industrial Application Field The present invention relates to a method for forming a metal pattern using a lift-off method.

Mouth) Conventional technology As for the conventional method of forming thin film patterns.

(A thin film is formed on the entire surface of the Al substrate, and then unnecessary parts are removed. (B) A film is previously formed on the parts of the substrate where the thin film is not to be formed, and a thin film is then formed on the entire surface. There are two types of methods: one in which the thin film is removed by subsequently removing the coating.

First, the method described above will be illustrated and explained using FIGS. 6 to 9. AI on silicon semiconductor substrate (1)!
A film (2) is deposited, a resist (3) is applied thereon, a photomask (4) is adhered thereto, and the resist (3) is exposed to ultraviolet light (5) (FIG. 6). There are two types of resist: negative type and positive type, and this example shows the case of negative type. When the resist (3) is developed, it has the shape shown in (6) in FIG. After that, remove the Al film (2) with a phosphoric acid etching solution and use AI! The wiring (7) is formed (FIG. 8), and the resist (6) is removed ('49 factor). However, with this method, AI! When the film is etched, it is also etched inward from the periphery, so p,! The film pattern is always smaller than the resist pattern. For this reason, it is impossible to form accurate fine patterns. Furthermore, if there are steps on the silicon substrate, the resist may not be completely removed and the Al film may remain unetched.

Next, the fBl method will be explained based on FIGS. 10 to 13. First, a resist (
2) is applied and exposed to ultraviolet light (5) through a photomask (4) (FIG. 10). Resist (2)
When developed using a negative type, a resist having the shape of (8) in FIG. 11 remains. In this state fi! By depositing the film (2) (Fig. 12) and removing the resist (6), the Al film (2) above it is also removed, leaving the p and l wiring (7) (Fig. 13). .

(With the Bl method, if an accurate pattern can be formed with the resist, the AJ film is formed as a negative pattern, making it easy to create fine patterns.

This method (g)) is generally called the lift-off method, and such a technique was developed, for example, by the Japanese Patent Publication Publication No. 58-45
It is described in No. 81Q, Special Publication No. 5B-46846, etc.

c) Problems to be solved by the invention By the way, in the lift-off method, if the resist is not made sufficiently thick (approximately 6.1μ), the A I Iu% (remains as 2+) that should be lifted off as shown in Figure 14. The AJ wiring (9) that should be used is not separated.For this reason, if the thickness of the resist is increased, it is likely to be deformed and peeled off during the heat during post baking or when using an etching solution (for example, hydrofluoric acid, phosphoric acid) for etching the substrate surface. Resist that does not deform or peel off due to etching solution or etching solution (for example, OMF+-
85,0NNR-22) may be used, but
Such resists do not easily dissolve in organic solvents such as acetone.

2) Means for solving the problems The present invention has been made in view of the above points,
A step of forming a resist on a substrate, a step of patterning this resist into a desired shape, a step of providing a resistive film on the substrate including this resist, a step of removing the resist by plasma etching, and a step of patterning the resist into a desired shape. and a step of removing the battle membrane by lift-off.

E) Function Since plasma etching is performed, a resist that is not easily deformed or peeled off by heat or the use of an etching solution for substrate surface treatment can be used, and the resist can be removed using the lift-off method.

f) Embodiments FIGS. 1 to 5 are cross-sectional views showing an embodiment of the metal film forming method of the present invention in the order of steps, and the present invention will be described in detail using these figures. First, 1μ thick n+1Nf1 on the surface.
G & A 8 f plate with 0+ formed (K on 111).

For example, 0NNR-22 (manufactured by Tosou Ohka) (regis)!
After applying 121, it was exposed to ultraviolet light for 14 seconds through a photomask α3, leaving a 4 μ wide line (Figure 1).
. Subsequently, development is carried out for 60 seconds, cleaning is performed for 60 seconds with Rinse H, cleaning is performed for 60 seconds with Rinse H, and a post bake is performed at 160° C. for 30 minutes to form a resist pattern (121) having a width of 4 μm and a thickness of approximately 1 μm. Figure]. Then use this resist (121 as a mask).

Using CCz 2 F 2 gas, 3X10 To
rr.

Etching is performed on the surface of the substrate [11] for 30 seconds under the condition of a gl Momouchi force of 0.517-, and a depression of 0.5 μ is made in the area other than the resist 117J portion (FIG. 3). Next, Au+Ge, Ni
.

A metal film α9 is formed by depositing Au in the order of 2000A, 1000A, and 2ooo1 (Fig. 4), and the resist az is removed by plasma etching using oxygen gas to form metal patterns with intervals of 4μ in width. a41ns
1Fe substrate ail (FIG. 5).

FIG. 15 is a schematic cross-sectional view of a Pel jar used to carry out the lift-off method of the present invention, and FIG. 16 is an exploded perspective view of various parts within the Pel jar. In these figures C61
is Pelger, σn is this Pelger (exhaust pipe that exhausts 1b1 circle, (181Qlc is 130x30 respectively)
Six plate electrodes are arranged facing each other with a size of 0 m and an interval of 150 m, and a high frequency electric field of 13.56 MHz and 250 W is generated. ril is a one-man tube that is installed under the electrode aa on the upper surface side, is set in a rectangular shape approximately the same size as the electrode a second, and is made of a pipe with many small holes. Supplied between flat electrodes 0 & Oa. C21+ is a shelf formed in the shape of a slit, and is arranged between the electrodes 0■a. This is a substrate holding stand bent in a 5-shape, and the substrate is held at an angle of 45° to 60° with respect to the electrode 0■δ plane.
A locking portion Q4J is provided to maintain and hold the angle.

When performing lift-off using such a device, the substrate c! When the substrate holding stand C241 is placed on the shelf, the electrodes 0810 on the substrate
81 to form an angle FIF of 45 to 60 degrees. In this state, while pulling the inside of the Pelger (lLbl) to 0.5-0.8℃ by suction from the exhaust pipe ση,
Oxygen gas is supplied from the tumor entry tube α9, and at the same time the electrode [18]
A high frequency electric field was generated at 16°56MHz and 250W between QE9.

Generates oxygen plasma. As a result, plasma is supplied to the substrate from an oblique direction, increasing the etching effect of the resist under the metal film. By performing etching for 15 minutes under the above conditions, a lift-off of 4 microns width was achieved. Therefore, using GaAS with μ-order lift-off, 7'? F
It can be used to form beam lead electrodes for F;T and Schottky diodes. As a reference example, in a case where the resist was etched without tilting the substrate under the above conditions, it took about 45 minutes to perform a lift-off of 4 microns width.

g) Effects of the Invention As described above, the method for forming a metal film of the present invention includes the steps of forming a resist on a substrate, patterning this resist into a desired shape, and forming a metal film on the substrate containing this resist. This method uses a resist that is not easily deformed or peeled off by heat or the etching solution used in substrate surface treatment. The pattern accuracy of the formed metal film is increased.

[Brief explanation of drawings]

1J111 to 85 are schematic cross-sectional views showing the metal film forming method of the present invention in the order of steps, FIGS. 6 to 9 are schematic cross-sectional views showing the conventional method of forming a metal film by etching in the order of steps, and FIGS. Fig. 13 is a schematic cross-sectional view showing the conventional lift-off method for forming a metal film in the order of steps; Fig. 14 is a schematic cross-sectional view showing a defective state in the lift-off process;
FIG. 5 is a schematic cross-sectional view of a Pel jar for carrying out the metal film forming method of the present invention, and FIG. 16 is an exploded perspective view of the internal parts of the Pel jar. α...G&AB board, (1z...resist, 031
... Photomask, f141 (15... Metal film,
(161... Pelger, [71... Exhaust pipe, 0
&0■...electrode, α1...air supply pipe, CA■...small hole, QB...shelf, z...substrate holding stand, c! 3...
Board, 3 leaks...locking part.

Claims (1)

[Claims] 1) A step of forming a resist on a substrate, a step of patterning this resist into a desired shape, a step of providing a metal film on the substrate including this resist, and a step of removing the resist by plasma etching and forming a metal film on the resist. A metal pattern forming method consisting of a lift-off removal process.