JPS6152566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which an electrode window and an electrode/wiring can be formed by self-aligning.

As the scale of semiconductor devices increases from ICs to LSIs and VLSIs, it has become an important issue to minimize the area of elements such as transistors, which are components of LSIs, in order to increase the degree of integration.

A method of forming a pattern by self-alignment that does not require a margin for alignment is an effective method for reducing the device area. From this point of view, the present invention attempts to achieve self-alignment in the process of forming electrode windows and electrodes/wirings.

Conventionally, when forming electrodes and wiring, first, as shown in FIG. The window 6, etc. were opened, and then, as shown in Figure b, an electrode metal layer such as aluminum (Al) was deposited by vapor deposition, etc., and this was patterned to form the base electrode 7, emitter electrode 8, etc. .

In such a method, the distance D between the electrode windows 5 and 6 is 2
The distance D ₁ between the two electrodes 7 and 8 must be added to the alignment margin D ₂ . For example, electrode spacing
When forming a fine pattern in which D ₁ is 2 [μm], the alignment margin D ₂ is required to be 3 [μm] to 4 [μm], so the electrode window interval D is 5 [μm] to 6 [μm].
m], and the element area increases accordingly. As a result, this not only hinders the increase in the density of semiconductor devices, but also has an adverse effect on the electrical characteristics of the device due to an increase in unnecessary area.

An object of the present invention is to provide a method for forming electrodes and wiring that does not require the above-mentioned alignment margin.

The method for manufacturing a semiconductor device of the present invention is characterized by forming a negative photoresist film on an insulating film covering a surface of a substrate to be processed, selectively forming a positive photoresist film on the negative photoresist film, and forming a positive photoresist film on the negative photoresist film. forming an opening in the insulating film by removing the exposed insulating film directly under the negative photoresist film by exposing the substrate to be processed to a hydrogen fluoride atmosphere under reduced pressure;
removing the exposed negative photoresist film to expose the opening of the insulating film to the surface of the substrate to be processed; depositing a metal film on the surface of the substrate including the positive photoresist film; The film and the remaining negative photoresist film are removed, and the electrodes and/or electrodes are brought into contact with the substrate to be processed in the opening of the insulating film and are led out onto the insulating film.
or a step of forming wiring.

Embodiments of the method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view and a top view of essential parts showing an embodiment of the present invention in the order of steps.

In the figure a, 1 is a silicon substrate, 2 is a base region, 3 is an emitter region, 4 is a silicon dioxide (SiO ₂ ) film covering the surface of the silicon substrate, 9 is a collector region, and 9' is a buried layer in the collector region. , 10
is the collector contact area. First of all
A polyisoprene-based negative photoresist such as OMR83 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to a thickness of approximately 5000 Å and left selectively in accordance with a predetermined pattern to form electrode windows for the base and emitter. A negative photoresist film 11 covering the area where the collector electrode window is to be formed and a negative photoresist film 11'' covering the area where the collector electrode window is to be formed are formed.This pattern is shown in the top view of a' in the same figure.

Next, as shown in FIGS. b and b', a novolak resin-based positive photoresist film 12 such as OFPR77 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is selectively formed to a thickness of about 2 μm, and the base and emitter layers are Openings 13 and 1 are formed in the areas where collector electrodes and wiring are to be formed.
3', 13'' are provided.

Next, the silicon substrate 1 is exposed to a hydrogen fluoride (HF) atmosphere at a pressure of about 10 [Torr] in a vacuum processing tank, and processed at a temperature of about 120 [°C] using the so-called dry ox method. As shown in FIG. 2c, openings 13, 13', 1
The SiO ₂ film directly under the 3'' portion where the surface is exposed is removed to form an electrode window.

Next, the negative photoresist films 11, 11', 11'' remaining in the electrode windows are removed by plasma assembling. Since the negative photoresist film 1 is formed thickly, the surface can be exposed by only slightly reducing the thickness.
Only 1, 11', 11'' are removed and the figure 2d,
As shown in d', the surface of the silicon substrate is exposed at the electrode windows 14, 14', 14''.

As already clear, the electrode windows 14, 14', 1
4'' is a portion located within the opening 13 of the positive type photoresist 12 and covered with the negative type resists 11 and 11', where the SiO ₂ film 2 is removed and the surface of the silicon substrate 1 is exposed. Further, in the portions which are within the openings 13, 13', 13'' and where no negative resist film is present, the SiO ₂ film 4 is not removed and remains with the surface exposed.

After this, aluminum (Al) or the like is deposited on the entire surface of the silicon substrate 1 using a vapor deposition method or the like, and then the positive type photoresist film 12 and the remaining negative type are coated by a method such as immersion in a photoresist stripping solution. By using a so-called lift-off method in which the photoresist film is removed and the aluminum layer deposited on the positive photoresist film 12 is removed at the same time, the base, emitter, and collector electrodes and wiring are removed as shown in FIG. 2e and e'. 15,1
5', 15'' are formed.

The electrodes/wirings 15, 15', 15'' are electrode windows 1
4, 14', and 14'' portions make ohmic contact with the surface of the silicon substrate 1, and are led out onto the SiO ₂ film 4 to form wiring.

In this embodiment, the photoresist film pattern used to form the electrode window is used as it is to form the electrodes and wiring, so the mutual positional relationship between the two is completely self-aligned. Therefore, the alignment margin D ₂ is not required, and the electrode window spacing D can be made equal to the electrode spacing D ₁ , making it possible to significantly reduce the element area.

In the above embodiments, a method for forming electrodes and wiring in contact with the surface of a semiconductor substrate has been described, but the present invention can also be used for forming multilayer wiring.

That is, as shown in the cross-sectional view of the main part of FIG. , 16' and the insulating film 4
The present invention can be practiced when forming second layer electrodes/wirings 17, 17' led out above. In such multilayer wiring, the electrode window becomes a through hole. Note that the first layer electrodes/wirings 16, 16' may be electrodes of a bipolar element or a MOS structure element, or may simply be a wiring layer.

Note that 4' is an insulating film that covers the surface of the substrate 1 to be processed.

Further, in the above embodiments, a semiconductor substrate was used as the substrate to be processed, but this need not be limited to a semiconductor substrate; for example, a hybrid circuit board or the like may be used.

As explained above, according to the method for manufacturing a semiconductor device of the present invention, electrodes and wiring can be formed in self-alignment with electrode windows, so alignment margins are not required, and the element area can be reduced, so that the semiconductor device It becomes possible to increase the degree of integration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part to explain a conventional electrode/wiring forming method, FIG. 2 is a cross-sectional view and a top view of a main part showing an embodiment of the present invention in order of steps, and FIG. FIG. 3 is a cross-sectional view of a main part showing a modification example of FIG. 1...Substrate to be processed, 2...Base region, 3...
Emitter region, 4... Insulating film, 10... Collector contact area, 11, 11', 11''... Negative photoresist film, 12... Positive photoresist film, 13, 13', 13''... Positive type Opening of photoresist film, 14, 14', 14''...electrode window, 1
5,15'15''...electrode/wiring, 16,16'...
...First layer electrode/wiring, 17,17'...Second layer electrode/wiring.

Claims (1)

[Claims] 1. A negative photoresist film is formed on an insulating film covering the surface of the substrate to be processed, a positive photoresist film is selectively formed on the negative photoresist film, and the substrate to be processed is placed in a hydrogen fluoride atmosphere under reduced pressure. The insulating film directly under the exposed negative photoresist film is removed by exposing the insulating film to form an opening in the insulating film, and the exposed negative photoresist film is removed to form a substrate to be processed in the opening of the insulating film. exposing the surface, depositing a conductive film on the surface of the substrate to be processed including the surface of the positive photoresist film, removing the positive photoresist film and the remaining negative photoresist film, and depositing the conductive film in the opening of the insulating film. A method for manufacturing a semiconductor device, comprising the step of forming an electrode and/or a wiring in contact with a processing substrate and led out on the insulating film.