JPS5885547A - Forming method for conductive pattern - Google Patents

Abstract

PURPOSE:To enable to form a conductive pattern having large thickness by forming the shape of the second pattern removed from the surface of a substrate substantially in an inverted trapezoidal shape in section in the final step. CONSTITUTION:When the entire surface of a negative resist film 13 is etched with oxygen plasma until the upper surface of a positive resist pattern 21A is completely exposed, the thickness of the film 13 becomes substantially equal to that of the pattern 12A, thereby forming a negative resist pattern 13A of substantially inverted trapezoidal shape in section longer in the length of the upper surface than the length of the lower surface. Then, the pattern 12A is completely dissolved and removed with a solvent which exhibits solubility to the pattern 12A and non solubility to the pattern 13A such as acetone, thereby allowing the pattern 13A of substantially inverted trapezoidal shape in section to remain on the substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming fine conductive wires, particularly metal wires.

As shown in FIGS. 1 to 3, there is a conventionally known method of forming an electrode metal layer having fine master turns on a substrate by using the so-called "lift-off method". For example, a boss-shaped photoresist/mother turn 2 is formed on the photoresist pattern 2 by a normal photolithography method (Fig. 1).Next, a wiring electrode metal layer 3 is formed on the resist pattern 2 by a vacuum evaporation method.
(FIG. 2). Thereafter, when the resist pattern 2 is removed using a solvent capable of dissolving and removing the renost/main turn 2, the metal 1 scratch 3 on the ston/main turn 2 is also removed together with the resist pattern 2. As a result, as shown in FIG. 3, a wiring metal layer 3 having a desired leanness is formed on the substrate 1. Good wiring metal obtained by implementing such a conventional method! -The shadow formation yield depends on whether the Lennost pattern 2 can be easily removed.

In order to easily remove the resist/main turn 2, the edges of the resist pattern 2 must be left exposed or well covered by the wiring metal layer 3 after the formation of the wiring metal layer 3. To achieve this, there is a limit to the relative ratio between the thickness of the Lennost film and the thickness of the wiring metal, and in general, the former must be approximately three times greater than the latter to ensure reliable wiring. It is difficult to form two turns of metal.If the Lennost film is formed thickly, it becomes possible to form a thick electrode wiring, but an increase in the resist film thickness generally reduces the resolution of the Lennost image. When the thickness of the metal film is reduced, if a step exists on the substrate, so-called "step breakage" occurs in the metal film.

An object of the present invention is to provide a method that can reliably form a conductive pattern having a sufficient thickness.

The method for forming a conductive two-turn structure of the present invention which can achieve the above object is to form a conductive double-turn structure on a substrate using a first material having a substantially trapezoidal cross section in which the length of the upper surface is longer than the length of the lower surface. forming a layer of a second substance on the surface of the substrate including the first turns; forming a layer of a second substance on the surface of the substrate including the first turns; Step of removing the first main turn to a depth where the upper surface protrudes; 2.
Step of leaving the turn on the substrate; 217th above)
A step of covering the surface of the substrate including the zR pattern with a conductive substance thinner than the thickness of the second groove; simultaneously removing the second groove and the conductive material thereon; The present invention is characterized in that it includes a step of leaving a third turn made of conductive rope on the substrate.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 1O.

A positive photoresist film (Tokyo Ohka Co., Ltd. product name: oFpRs 00) is formed on the substrate 1 to a thickness of 1.0 μm by spin coating, heated to approximately 90°0 to evaporate the solvent, and then subjected to conventional coating. The above film is selectively removed by photolithography to form a positive pattern (turns 12) (FIG. 4).

Next, when the positive resist pattern 12 is heated at a temperature of 140 to 160°C for 10 to 20 minutes, the positive resist pattern 12 is
2 is thermally deformed to form a positive resist pattern 12A having a substantially trapezoidal cross section in which the length of the upper surface is shorter than the length of the lower surface (FIG. 5). A negative photoresist film J3 (trade name: OMR-83, manufactured by Tokyo Ohka Co., Ltd.) is formed on the surface of the substrate 11 including the porcyst turns 12k to a thickness of 2.0 μm by spin coating (FIG. 6).

In this case, as is clear from FIG. 6, the thickness of the negative resist film 13 located on the positive resist layer 12A is necessarily thinner than the thickness of the negative resist film 13 located on the substrate 11.

Next 1. T? The entire surface of the negative resist film 13 is etched using oxygen plasma until the upper surface of the positive resist flat turf 12 is completely exposed. As a result, the thickness of the negative resist film 13 is almost the same as the film thickness of the I sole resist f-turn 12, and = 5 - the negative resist film 13 has a substantially inverted trapezoidal cross section in which the length of the upper surface is longer than the length of the lower surface. A turn 13k is formed (FIG. 7).

Next, positive resist pattern J,? Using a solvent (for example, acetone) that shows solubility in A and non-solubility in the negative resist/mother turn 13A, the T4 turn 121L is completely dissolved and removed, and a negative resist No. 11 (Figure 8). Next, heat at 80° C. for 10 minutes to evaporate acetone. At this temperature, the negative resist is approximately inverted trapezoidal) No. 4
The turn 13 can maintain its original shape without being deformed. Thereafter, a wiring metal 5, for example, At, is deposited on the surface of the substrate 11 including the negative resist pattern 13A by vapor deposition to make the wiring metal 5 thinner than the thickness of the negative resist/mother turn 13A, for example, about 0.8
The wiring metal layer 14 is formed by depositing it to a thickness of μm (Fig. 9).
.

As is clear from No. 91m, since it is difficult for wiring metal to adhere to the side surface of the negative resist/mother turf 131L, the wiring metal is deposited on the upper surface of the negative resist/mother turf 131L.
The metal layer 14 deposited on the upper surface of the substrate 11 is separated from the metal layer 14 deposited on the upper surface of the substrate 11. Therefore, in the next step, the metal layer 1-14 formed thereon along with the negative resist pattern 13 is removed. The task of doing so is extremely easy to perform. Finally, use a resist stripping solution (OMR stripping solution manufactured by Tokyo Ohka Co., Ltd., trade name) to remove the negative resist pattern 1.
3A and its AtI #14 are simultaneously removed to obtain the desired wiring electrode z mother turn 14 (FIG. 10).

In the above-mentioned embodiments, positive type 7 photoresist was used as the first pattern forming material and negative type photoresist was used as the second pattern forming material, but in the present invention, the first and second pattern forming materials are each of the above. You can do it the other way around. Alternatively, silicon oxide may be used as the first mother turn forming material, and a resin that can be formed by coating, such as polyimide, may be used as the second mother turn forming material. Further, in the above embodiment, a metal such as At was used as the material for forming the conductive pattern, but the present invention may also use other conductive materials such as doped polysilicon to which impurities are added.

As explained above, the present invention prevents the conductive material from adhering to the side surface of the second pattern by making the shape of the second pattern removed from the substrate surface in the final step substantially inverted trapezoidal in cross section. However, this makes it possible to easily form a conductive/mother turn with a large film thickness.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views showing the conventional method at step J@;
4 to 10 are cross-sectional views showing a method according to an embodiment of the present invention in order of steps. 1. Board, 7. 'A...first 1° turn, J
, 9A...second hole or turn, 14...conductive pattern.

Claims (1)

[Claims] A step of forming a first mother turn made of a first material having a substantially trapezoidal cross section in which the length of the upper surface is shorter than the length of the lower surface on the substrate; the first two turns; forming an I- made of a second material on the surface of the substrate containing the second material; removing the I- made of the second material to a depth where the upper surface of the first nine turns is exposed; removing the pattern and thereby leaving on the substrate a second pattern made of a second material having a generally inverted trapezoidal cross section in which the length of the upper surface is longer than the length of the lower surface; including the second flat turn; Coating the surface of the substrate with a conductive material thinner than the thickness of the second setane; removing the second setane and the conductive material thereon at the same time, thereby depositing a conductive material on the substrate. A method for forming a conductive i-pattern, comprising the step of leaving the pattern of step 3. 1-