JPS58201330A - Formation of conductor film pattern - Google Patents

Abstract

PURPOSE:To obtain a conductive film at the clean surface and eliminate deterioration at the interface by providing selectively a photo sensible resin on an insulating film deposited on a substrate, and depositing a conductive film, removing the resin and leaving the conductive film at the etching area after etching the insulating film up to the interim area with said resin used as the mask. CONSTITUTION:An Si3N4 film 2 is deposited as thick as those to be removed by etching on the GaAs substrate 1 and a mask consisting of positive photo sensible resin 3 is formed at the area where a metal wiring is not provided. The substrate 1 is exposed to the CF4 plasma, the exposed part of film 2 is etched in order to remove the film as much as an increased thickness, and the surface is purified and the edge 5 of mask is extruded like a penthouse. Thereafter, the Au layer 4 is vacuum-deposited while it is discontinued at the remaining film 2 and the resin 3. The resin 3 is removed together with the upper layer 4 and thereby the Au wiring pattern 4a can be obtained. Next, an Si3N4 film 6 is deposited for obtaining a multi-layer wiring and an Au wiring 7 is again formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a conductive film pattern, and particularly to a treatment before metal deposition in a lift-off method.

The lift-off method is used for metals that are difficult to pattern by etching. For example, when a gallium arsenide (GaAs) substrate is used as a semiconductor substrate and gold (Au) wiring is provided on a silicon nitride (Si3N4) film as an insulating film, it has been carried out as follows.

As shown in FIG.
On the surface of the Si3N4 film 2 having a thickness of 3,000 layers deposited by method D, a photosensitive resin 3 is selectively deposited on areas where metal wiring is not desired. Here, selective application of the photosensitive resin is achieved by spin-coating the photosensitive resin to a thickness of, for example, 1.4 .mu.m, followed by exposure and development using a desired mask. After this development, the photosensitive resin is washed with an organic solvent or water. Thereafter, an Au layer 4 is deposited to a thickness of, for example, about 6,000 mm using a vacuum evaporation method or the like.

Next, by removing the photosensitive resin 3 with a solvent, the Au layer 4 deposited on the surface of the photosensitive resin 3 is also removed at the same time. Then, as shown in FIG. 2, a desired Au pattern 4a is formed. Here, the steeper the edge part of the photosensitive resin 3, the easier the lift-off becomes. Conversely, if the edge part of the photosensitive resin 3 is gentle, the Au layer 4 will break on the slope of the photosensitive resin 3, thereby preventing the solvent from entering. This makes lift-off difficult.

In such a method, only cleaning with an organic solvent or water is performed before metal deposition, and 10% of the surface of the Si3N4 film 2 is
A thin photosensitive resin with a thickness of 00 Å or less remains, which causes deterioration in reliability due to peeling of the Au layer 4 and deterioration of the interface during lift-off. Further, on the flat surface of the Si3N4 film 2,
The U layer 4 protrudes by 6000 nm, so when an insulating film is further applied to form a multilayer wiring, the adhesion of the insulating film on the side surface of the Au layer may be poor, causing a short circuit.
The stepped portions often caused disconnections in the second layer metal wiring.

The present invention provides a method for forming a conductive film pattern that solves the above-mentioned drawbacks. Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG.
6008 0813N4 film 2 deposited by C, V, D method
AZ1350 (trade name) 3 as a positive type photosensitive resin 3 is spin-coated on top to a thickness of about 1.471 m, and after exposure with a mask, development is performed by immersing in a developer, and cleaning is performed by rinsing with water. As a result, the photosensitive resin 3 is selectively deposited on areas where metal wiring is not desired. l
The resin layer 3 is then exposed to CF4 plasma.
The Si3N4 film 2 in the area where the S Z 3N4 film 2 was not deposited is etched until the middle of the process, as shown in FIG.

As a result, the exposed surface of the Si3N4 film 2 is in a clean state without any remaining film of the photosensitive resin 3 as described above.

Furthermore, since the Si3N4 film 2 is etched laterally as well, a canopy 6 is formed by the resin 3.

Next, as shown in FIG. 6, an Au layer 4 of approximately 50° is deposited by vacuum evaporation. At this time, the Au layer 4 wraps around the lower part of the eaves 5 and is deposited to approximately 150°, but there is no space. Even if the slope of the edge of the resin 3 is somewhat gentle, the eaves 5 has Au on the slope.
This prevents or significantly reduces the adhesion of layer 4.

Next, the resin 3 is removed by immersing it in acetone or a photosensitive resin stripping solution 1-100 (trade name), and an Au wiring pattern 4a is formed as shown in FIG. Here, the adhesion of the Au layer 4 to the slope of the resin 3 is small, and the thickness of the resin 3 exposed due to the space created by the eaves 6 and the step difference due to the etching of the S L 3N4 film 2 becomes thicker.
The resin layer 3 can be easily melted by acetone or l-1oo, and lift-off can be easily performed.

After that, as shown in Figure 7, 513N4 for multilayer wiring
After forming 5,000 layers of the film 6, 5,000 layers of Au7 are selectively deposited on the surface of the Si3N4 film 6 as a second layer wiring. At this time, the first layer Au 4 is formed in the etched recess, and since the protrusion of the Au layer 4 is small, the adhesion of the Si3N4 film 6 is good, and the Au layer 4 is formed in the etched recess.
Disconnection of the layer 7 can also be eliminated.

As explained above, in the present invention, by etching the surface to which a conductive film such as metal is deposited, the metal is deposited on a clean surface, improving adhesion and reducing reliability due to interface deterioration. This not only prevents this, but also facilitates lift-off.

Furthermore, the protrusion of the conductive film such as metal is reduced by the etched thickness, achieving flattening, and prevents insulator adhesion and disconnection of the second layer metal when making multilayer wiring, which improves yield. It is something that improves.

Note that the substrate used in the explanation may be other semiconductors, ceramics, etc., and the insulator may be silicon oxide, alumina, etc.

In addition to Au, the metals are Al and Mo.

W or the like may be used, but there is no particular limitation, and it goes without saying that the present invention can also be implemented in the second and third layer metal wiring.

[Brief explanation of drawings]

The first diagram is a cross-sectional view of the process for explaining the conventional wiring pattern forming method;
The figure is a process sectional view showing a method for forming a wiring pattern according to an embodiment of the present invention. 1...G a A a board, 2,6...
・Si3N4 film, 3...photosensitive resin, 4,7・
...Au, 4a...Au pattern. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 5 Figure 6 Figure 7 4ζ

Claims (1)

[Claims] a step of selectively depositing a photosensitive resin on the insulator deposited on the substrate; a step of etching the insulating film halfway using the photosensitive resin as a mask; and a step of depositing a conductive film. A method for forming a conductive film pattern, comprising the step of removing the photosensitive resin and leaving the conductive film in the etched portion of the insulating film.