JPS6295856A - Formation of metallic pattern - Google Patents

Abstract

PURPOSE:To facilitate the formation of fine metallic patterns, by forming a resist pattern on a substrate, applying plasma vertically to the surface of the pattern, depositing a metal layer on the surface and removing the pattern together with the overlaid metal layer. CONSTITUTION:A semiconductor substrate 1 is provided with resist 3 having a pattern opened according to a design as desired. Plasma 7 containing F or Cl is applied approximately vertically to the surface of the pattern 3. The substrate is then dipped in an organic solvent so that the pattern 3 is configured to have an undercut space. A metal 4 is vapor deposited on the whole surface and the pattern 3 is removed together with the overlaid metal 4 by the lift-off technique. A fine metallic pattern 5 can be provided in this manner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming fine metal patterns using lift-off for electrodes and wiring of semiconductor devices.

(Prior Art) As the performance and integration of semiconductor devices progresses, techniques for forming fine patterns have become extremely important.

A conventional metal pattern forming method will be explained based on FIGS. 2 and 3.

As shown in FIG. 2(a), a semiconductor substrate]-Si3
After forming a resist pattern 3 on a thin film (spacer) 2 such as N4 or 5i02, as shown in FIG.
), using resist pattern 3 as a mask,
The spacer 2 is etched to form an undercut-shaped gap suitable for lift-off.

Thereafter, as shown in FIG. 2(c), a metal 4 is deposited on the entire surface, and the metal on it is removed together with the resist pattern 3 and spacer 2 by a lift-off method, resulting in a metal as shown in FIG. 2(d). Form pattern 5.

As shown in FIG. 3(a), after coating the resist 6 on the semiconductor substrate 1, it is immersed in chlorobenzene, exposed and developed, or exposed and then immersed in chlorobenzene.
When developed after that, in either case, the surface of the resist 6 becomes difficult to dissolve in the developer, so that undercut-shaped voids suitable for lift-off are formed as shown in FIG. 3(b).

Thereafter, as shown in FIG. 3(C), a metal 4 is deposited on the entire surface, and the resist pattern 3 and the metal 4 thereon are removed by a lift-off method, resulting in a metal pattern as shown in FIG. 3(d). form 5.

(Problems to be Solved by the Invention) In the above configuration, when using a spacer, Si, N4
Since a thin film of SiO or SiO□ must be formed, the process becomes complicated and etching is difficult to control. Furthermore, when chlorobenzene treatment is performed, the cross-sectional shape of the resist pattern changes depending on the chlorobenzene solution temperature and dipping time, resulting in poor reproducibility.

The purpose of the present invention is to eliminate the conventional drawbacks and to
It is an object of the present invention to provide a metal pattern forming method that does not use a spacer such as iO□ and has a simple process.

(Means for Solving the Problems) The metal pattern forming method of the present invention involves forming an organic resin thin film layer with a watermark of a desired pattern on a substrate, and applying plasma containing F or C1l to the organic resin thin film layer. After the layer is irradiated in a substantially perpendicular direction and then immersed in an organic solvent to form a metal layer on the entire surface, the organic resin thin film layer is removed together with the metal layer above it.

(Function) The above configuration eliminates the need to use spacers such as Si, N, or 5in2, making the process extremely simple and eliminating the need to etch spacers. In addition, it has excellent reproducibility because it is only necessary to irradiate F or Cρ plasma almost perpendicularly to the surface of a resist pattern of a predetermined shape and then immerse it in an organic solvent, making metal evaporation and lift-off easier. This makes it possible to form a metal pattern.

(Example) An embodiment of the present invention will be described based on FIG.

FIG. 1 is a process sectional view of the metal pattern forming method of the present invention. In this figure, the same parts as those in the conventional example shown in FIGS. 2 and 3 are given the same numbers, and the explanation thereof will be omitted.

As shown in FIG. 1(,), after forming an organic resin thin film layer (resist pattern) 3 with a watermark of a desired pattern on a semiconductor substrate 1, as shown in FIG. 1(b), an F
Alternatively, the plasma 7 containing C& is irradiated almost perpendicularly to the surface of the resist pattern 3.

After that, it is immersed in an organic solvent to form a resist pattern 3 having an undercut-like void as shown in FIG. 1(C), and a metal 4 is deposited on the entire surface as shown in FIG. 1(d). , the resist pattern 3 and the metal on it were removed by the lift-off method, and the metal pattern 5 was removed as shown in FIG.
Form as shown in e).

A more detailed explanation will be given below based on FIG. 1.

First, a resist pattern 3 is formed on a semiconductor substrate 1. The resist pattern 3 can be formed, for example, by the following steps. On the semiconductor substrate 1, Tokyo Ohka (
Co., Ltd. photoresist 0FPR-800 was applied to a thickness of 1.2 μm, and prebaked at 85° C. for 20 minutes.

Next, exposure was performed using a stepper at 100 rnJ/cJ to expose a 0.8 μm pattern, and
A resist pattern 3 can be formed by developing for 1 minute using developer NMD-3 manufactured by Co., Ltd. As shown in FIG. 1(b), the resist pattern 3 is irradiated with plasma (7) almost perpendicularly to the surface of the resist pattern 3 using a reactive ion etching device using gas CCj, 10□. Plasma irradiation (7) is performed for the purpose of altering the resist surface. Next, by immersion in isoamyl acetate, a resist pattern 3 having undercut-shaped voids as shown in FIG. 1(c) is formed. After that, using an electron beam evaporation device, AI
is deposited, and the resist pattern 3 and the metal 4 thereon are removed by a lift-off method, thereby forming an AN metal pattern 5 as shown in FIG. 1(e).

In the above embodiments, the positive photoresist 0FPR-800 made of diazo novolac resin was described, but resist patterns can be formed in the same way with other resists. Also, instead of 00g410□, CF
Pattern formation can be similarly performed with plasma irradiation using gas No. 4102.

Note that plasma irradiation can remove resist residue and clean the surface of the semiconductor substrate in the metal vapor deposition area, and also improves the heat resistance of the resist, so that the metal pattern width does not change even if the substrate is heated during metal vapor deposition.

(Effects of the Invention) According to the present invention, an undercut shape can be easily obtained, and a fine metal pattern can be easily formed by a lift-off method.

[Brief explanation of drawings]

FIG. 1 is a process sectional view of a metal pattern forming method according to an embodiment of the present invention, and FIGS. 2 and 3 are process sectional views of a conventional example. 1...Semiconductor substrate, 2...Spacer, 3.
・・・Resist pattern, 4...Metal, 5...
Metal pattern, 6... resist, 7... plasma. Patent applicant Matsushita Electronics Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An organic resin thin film layer with a watermark in a desired pattern is formed on a substrate, and a plasma containing F or Cl is irradiated almost perpendicularly to the organic resin thin film layer, and then immersed in an organic solvent to completely cover the metal layer. 1. A method for forming a metal pattern, characterized in that the organic resin thin film layer is removed together with the metal layer thereon.