JPS6159751A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To use a photo resist provided on an insulation film as the mask for dry etching and lift-off as the material having excellent dry etching characteristic by making small solubility for the developer through processing with monochrol benzene to said photo resist. CONSTITUTION:An insulation material layer 13 and a photo resist film 14 are formed on the main surface of a semiconductor substrate 12. Next, it is processed with the monochrol benzene to convert the surface of film 14 into the converted part 14a which does not easily dissolve into the developer. The pattern is exposed and developed to form an overhanging aperture 15 and thereafter an aperture 16 which reaches the main surface of substrate 12 is formed by the reactive ion beam etching with the film 14 used as the mask. Next, an electrode material 17 is deposited to the inside of hole 16 of layer 13 and on the film 14, the film 14 is removed and a wiring material 19 is deposited. Thereafter, electrode wiring is formed by patterning the material 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention particularly relates to a method of manufacturing a semiconductor device in which a means for drawing out an electrode portion of a semiconductor substrate to a wiring portion is improved.

[Technical Background of the Invention] There are two methods for forming electric bridge wiring in a semiconductor device: a method in which an electrode portion and a wiring portion are formed at the same time, and a method in which they are formed separately. The latter method is called the lift-off method.

In the former method, first, as shown in FIG. 3A, an insulator layer 33 is provided on the main surface of a semiconductor substrate 32 on which a predetermined electrically active layer, here a resistance layer 31, is formed. Then, an opening 34 is formed in this insulator layer 33, and a hole 34 is formed in the semiconductor substrate 3.
The electrode formation region on the main surface of No. 2 is exposed.

Next, as shown in 31iJ(B), the insulator layer 33
An electrode wiring material is deposited on top and in the opening 34 by sputtering to form an electrode wiring material layer 35.

Furthermore, this electrode wiring material 1135 is selectively etched to form electrode wiring 3B as shown in FIG. 3(C).

On the other hand, in the lift-off method, first, as shown in FIG.
A first insulator layer 43 made of silicon oxide, for example, is formed on the main surface of the substrate. Then, this first insulator layer 43
A second insulating layer 4 made of phosphosilicate glass (PSG) or the like having a faster etching rate than this insulating layer 43 is provided thereon.
4 is formed, and a photoresist 1I45 is roughly formed on this second insulating layer 44. Thereafter, this photoresist 111I45 is exposed to light to form mask holes facing the electrode formation regions at both ends of the resistance layer 41.

Next, as shown in FIG. 4(B), the first
The insulator layer 43 and the second insulator 1i144 are etched to form an opening 46 to expose a part of the surface of the resistance layer 41, that is, a region where an electrode is to be formed.

Here, the opening 46 has a size similar to that of the mask hole for the first insulating layer 43, and is larger than the mask hole for the second insulating layer 44 due to its high etching speed. It is formed to a larger diameter than the Therefore, the portion of the photoresist 45 around the mask hole protrudes from the opening 46 like a canopy.

Next, as shown in FIG. 4(C), electrode material 4 is deposited on the photoresist 1145 and in the opening 46 by sputtering.
Deposit 7. Here, the photoresist film 45 is
Since the electrode material 47 covers the hole 6 like a canopy, the electrode material 47 extends around the opening with the photoresist film 4S as the border.

The deposits are completely separated between the surrounding area and the inside of the aperture.

Thereafter, as shown in FIG. 4(D), the photoresist [
145 is removed. At this time, as described above, the electrode material is deposited completely separately around the hole and inside the hole, so that it is easily controlled only in the electrode formation region on the main surface of the resistance layer 41.
Electrode material 47 can be left behind to form an electrode section.

Then, as shown in FIG. 4E, a wiring material 48 is deposited on the second insulator 1144 including the remaining electrode portion. Further, the deposited wiring material 48 is selectively etched to form wiring, thereby obtaining a resistance device having electrode wiring 49 shown in FIG. 4(F).

The two types of methods for forming electrode wiring have been described above, with respect to the case of forming single-layer wiring, but multilayer wiring can also be formed by these methods.

[Problems with the Background Art] In the method for forming electrode wiring of a semiconductor device described above, first,
In the method shown in FIG. 3, when forming the electrode wiring material layer 35 by the sputtering method in FIG. Have difficulty. Therefore, as shown at 37 in this figure, in the vicinity of the opening 34, the electrode wiring material l
There is a high possibility that 135 will be separated onto the insulator 1133 and inside the opening 34. This is the electrode wiring 36 in FIG. 3(C).
This will lead to a disconnection condition. Such disconnection is particularly likely to occur when forming an electrode that is miniaturized to the submicron region, and in which the diameter of the electrode opening is smaller than the thickness of the insulating layer.

Therefore, attempts have been made to prevent this disconnection by making the holes formed in the insulator layer tapered, such as the holes 38 in FIG. 3(D), but the electrode wiring material layer 39 Figure (E)
The problem of wire breakage as shown at 40 has not been solved.

On the other hand, in the lift-off method, as explained with reference to FIGS. 4(D) and (E), the wiring material 48 is deposited on the electrode material 47 left as the electrode part. , so there is no problem with wire breakage. However, in this method, in order to cover the opening 46 in the form of a canopy, various steps are performed, namely, a second insulator made of a material having a higher etching rate than the first insulator layer 43 is formed on the first insulator layer 43. The manufacturing process is complicated because it requires a step of providing layer 44 and a step of forming photoresist film 45 on this second insulating layer.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device that can form an IF electrode wiring without disconnection and a smaller number of steps.

[Summary of the Invention] That is, in the method for manufacturing a semiconductor device according to the present invention, first, a photoresist is applied on an insulating layer formed on the main surface of a semiconductor substrate to form a photoresist film;
This photoresist film is subjected to a treatment such as an organic solvent treatment to modify only the surface portion of the photoresist so that it is difficult to dissolve in a developer.

Then, the photoresist film whose surface portion has been modified is exposed to light using a mask having a pattern for forming electrodes, and then developed. Through this development, openings with a size matching the pattern are formed on the surface of the photoresist, which has been modified to be less soluble in the developer.
Since the internal unmodified portion is more easily dissolved in the developer than the surface portion, the opening formed in the photoresist has an overhang shape in which the inside is larger than the surface.

After this development, dry etching is performed perpendicularly to the insulating layer using the photoresist having the overhang-like opening as a mask to form an opening reaching the main surface of the semiconductor substrate. Expose the electrode contact area of the main surface. In this directional dry etching,
Openings corresponding to the shape of the modified surface of the photoresist film are obtained.

Next, an electrode material is deposited in the opening of the insulating layer to form an electrode portion, and then the photoresist is peeled off. Roughly, a wiring material is deposited on the insulating layer including the electrode part, and this is patterned to form a wiring part, which is combined with the electrode part to complete the electrode wiring.

Note that the term "semiconductor substrate" here refers not only to the substrate itself made of a normal semiconductor material, but also to the case where an oxide layer, electrically active region, or electrode wiring is formed on the main surface of such a substrate. It also refers to

[Embodiments of the Invention] Hereinafter, with reference to the drawings, one diagram of a semiconductor device according to the present invention (A
), N+low resistance! An insulator [13 is formed on the main surface of the P-type silicon semiconductor substrate 12 having a layer 111, and a positive photoresist is further applied on the insulator layer 13 to form a photoresist [114].

Next, monochlorobenzene treatment is performed, and as shown in Figure 1 (B).
The surface portion of the photoresist film 14 is modified so that it is difficult to dissolve in a developer. Hereinafter, this surface portion will be referred to as a modified portion 14a.

The photoresist modification treatment performed here is treatment with an organic solvent such as monochlorobenzene (M.

HfltZakis et al. IBM J, Res De
velop, 1980 Vol, 24. No, 4
PaQe452-460), oeepuv processing <
Robert AHen et al. J.E.C.S. 1982
．． Vol, 129 No. 6 Paae 1379
~1381 etc.) or plasma treatment (J, M
, P IoIIbley et al. IE3EDL-3, No.
4 1982 Paae99-100, etc.).

Thereafter, the photoresist whose surface portion has been modified is exposed to light using a plate having a pattern for forming electrodes, and then developed. In this way, an overhang-shaped opening 15 shown in FIG. 1(C) is formed. The reason why such an overhang-like opening 15 is obtained is that an opening of a size matching the pattern for forming an electrode is formed in the modified portion 14a of the photoresist surface portion, but an opening of a size matching the pattern for forming an electrode is formed in the modified portion 14a of the photoresist surface. This is because the unmodified portion 14b is more easily soluble in the developer than the modified portion 14a, so that openings larger than the surface portion are formed inside the unmodified portion 14b.

After the development, reactive ion beam etching is performed in a direction perpendicular to the main surface of semiconductor substrate 12 using photoresist 1114 having overhang-shaped openings 15 as a mask. As a result of this etching, as shown in FIG.
exposing the electrode contact area of the major surface of the electrode. Here, since the reactive ion beam etching has a direction perpendicular to the semiconductor substrate 12, the surface of the opening 15 of the photoresist film 14 is etched in the insulating layer 13, as shown in the drawing. An opening 16 corresponding to the shape of the part is formed. This reactive ion beam etching is performed using a mixed gas of tetrafluoromethane and hydrogen.

Next, as shown in FIG. 1(E), the inside of the opening 16 formed in the insulator 113 and the photoresist 114 are
An electrode material 17 such as aluminum-silicon is deposited thereon by sputtering. This sputtering method is also set in a direction perpendicular to the semiconductor substrate 12, similar to the ion beam etching. Therefore, as shown in the drawing, the insulator 1113 has 't!' only in the portion below the surface portion of the opening 15! The i-pole material is deposited to form the electrode portion 18.

Next, as shown in FIG. 1(F), a photoresist 11
14 is peeled off. At this time, N on the photoresist film 14
The pole material 17 is removed together with the photoresist $14, but the electrode material of the electrode portion 18 is selectively left behind.

After removing the photoresist film 14 in this way, the photoresist film 14 is removed as shown in FIG.
G), the insulator layer 1 including the above electrode part 18
3, a wiring material 19 such as aluminum-silicon is deposited by sputtering.

Then, this deposited wiring material 19 is patterned to form a wiring part, and further sintered to form a first
A resistor device having electrode wiring 20 as shown in Figure (H) is completed.

By the modification treatment carried out in the above embodiments, the photoresist is hardened and becomes less soluble in a developer and at the same time has excellent dry etching resistance.

Therefore, even after being used as a mask during dry etching of an insulating layer, it can be used as is as a lift-off mask, that is, a mask for sputtering electrode material.

Note that as the electrode wiring material, in addition to aluminum-silicon, a high melting point metal or a silicide of a high melting point metal can also be used.

Further, in the above embodiments, a case was explained in which a single-layer wiring was formed, but it is also possible to form a multi-layer wiring by this method. In that case, first, an insulator 1725 is formed on the semiconductor substrate 24 on which the N active layer 21 and the electrode wirings 22, 23 have been formed in advance as shown in FIG. 2(A). Furthermore, a photoresist 1126 is formed on this insulator 1l125.

Then, as in the previous embodiment, this photoresist 2
After modifying the surface portion of 6, exposure and development are performed to form overhang-shaped openings 27 as shown in FIG. 2(B).

Next, using this opening 27, the insulating layer 23 is etched to form an opening 28 shown in FIG. 2(C).

Then, electrode material 29 is deposited as shown in FIG. 2(D).

Hereinafter, the electrode arrangement 113G shown in FIG. 2(E) is formed by the method described with reference to FIGS. 1(G) and (H).

[Effects of the Invention] As described above, in the method for manufacturing a semiconductor device according to the present invention, the surface portion of the photoresist film provided on the @edge layer is subjected to a modification treatment, thereby improving the quality of the photoresist film. An overhang-shaped opening is formed. The photoresist film having the openings is then used as a mask twice: when etching the insulator layer and when forming the electrode portion. Therefore, electrode wiring without disconnection can be formed by the lift-off method with fewer steps than in the conventional method.

[Brief explanation of drawings]

FIG. 1 is a process sectional view for explaining one embodiment of the method for manufacturing a semiconductor device according to the present invention, the second factor is a process sectional view for explaining another embodiment, and FIGS. 3 and 4 2A and 2B are process cross-sectional views for explaining a conventional method for manufacturing a semiconductor device. 11--Resistance ia, 12-Half 1 body 1 plate, 13-Iaa body m, 14--Photoresist film, 15--Opening, 1
7... Electrode material, 18... Electrode part, 19-... Wiring material, 20... Electrode wiring. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A step of forming a photoresist film on an insulating layer formed on the main surface of a semiconductor substrate, and modifying only the surface portion of the photoresist film so that it is difficult to dissolve in a developer. A step of exposing a pattern for forming an electrode on the photoresist film with the modified surface portion and then developing it to form an opening that is larger inside than the modified surface; The insulating layer is etched to correspond to the shape of the modified surface of the opening formed in the opening, and the insulating layer is etched to expose the electrode contact area of the semiconductor substrate. a step of forming an opening that reaches the main surface; a step of depositing an electrode material in the opening of the insulating layer to form an electrode portion; a step of peeling off the photoresist; and a step of removing the formed electrode. A method for manufacturing a semiconductor device, comprising the steps of: depositing a wiring material on the insulating layer from which the photoresist has been peeled off, including the portion thereof, and patterning the wiring material to form a wiring portion.