JPH02266517A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve yield and throughput at the time of the formation of a fine pattern by executing specific etching while using the mask layers of three layers on a layer to be etched formed onto a semiconductor substrate as masks. CONSTITUTION:A first mask layer 5 is patterned through photolithographic treatment, a second mask layer 7 in thickness thinner than the pattern interval (d) of the layer 5 is applied and a sidewall section 7A is shaped, and the width (h) of the sidewall section of the second mask layer 7 is made smaller than the pattern interval (d). A third mask layer 9 is applied onto the second mask layer 7. The selection ratios of etching of each mask layer 5, 7, 9 differ, and the top face of a layer to be etched in the sidewall section 7A is exposed when only the second mask layer 7 is removed selectively through a specified etching process. Etching is conducted while using the residual first mask layer 5 and third mask layer 9 as masks. Accordingly, yield is improved and throughput is also enhanced when a fine pattern is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a semiconductor device, for example, a method of processing a fine electrode pattern using RIE.

<Prior Art> As a conventional method for manufacturing this type of semiconductor device, there has been a method as shown in FIGS. 2(a) to 2(C), for example. This shows a method of forming an electrode pattern of a bipolar transistor.

First, as shown in FIG. 3A, an electrode metal 3 made of aluminum or the like is deposited on a semiconductor substrate 1 on which a semiconductor device (not shown) is formed, and a photoresist 9 is applied on the metal 3. Apply.

Next, as shown in FIG. 3(b), this photoresist 9 is coated at a predetermined interval d(2) by a well-known photolithography process.
(on the order of μm) to expose a part of the surface of the electrode metal 30.

Thereafter, as shown in FIG. 2C, the electrode metal 3 was etched using the photoresist 9 as a mask, and the photoresist was removed to obtain a desired electrode pattern. 3A in the figure.

3B and 3C indicate, for example, base, emitter, and collector electrodes.

<Problems to be Solved by the Invention> However, in such a conventional semiconductor device manufacturing method, the distance d between each electrode depends on the accuracy of photolithography, that is, the performance of the photolithography equipment used for this process. It was highly dependent on.

As a result, in order to obtain fine patterns, it is necessary to use high-grade photolithography equipment, resulting in problems such as low yield, low throughput, and complicated maintenance of the equipment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that has a high yield and improved throughput in forming fine patterns.

<Means for Solving the Problems> A method for manufacturing a semiconductor device according to the present invention includes a step of depositing a first mask layer on a layer to be etched formed on a semiconductor substrate, and a step of depositing a first mask layer on a layer to be etched formed on a semiconductor substrate. forming a second mask layer on the layer to be etched and the first mask layer to a thickness smaller than the spacing; covering the sidewalls of the first masking layer with the sidewalls of the second masking layer, and covering the second masking layer between the opposing sidewalls with a third masking layer; a step of exposing a part of the upper surface of the layer to be etched by selectively removing the sidewall portion of the second mask layer;
The method is characterized in that it includes a step of etching the layer to be etched using the mask layer and the third mask layer as masks.

Effect> In the method for manufacturing a semiconductor device according to the present invention, the first mask layer is patterned by a well-known photolithography process. In this case, the pattern spacing may be approximately the same as in the conventional case. Then, a second mask layer having a thickness thinner than the pattern spacing is applied thereon to form a side wall portion. This second
The width of the side wall portion of the mask layer is smaller than the pattern interval.

A third mask layer is then deposited on the second mask layer between opposing sidewall portions of the second mask layer.

In this case, the first, second, and third mask layers have different etching selectivity.

Therefore, when only the second mask layer is selectively removed by a predetermined etching process, the upper surface of the layer to be etched on the sidewall portion is exposed. Thereafter, a desired fine pattern is formed by etching using the remaining first mask layer and third mask layer as masks.

<Example> Hereinafter, an example of the method for manufacturing a semiconductor device according to the present invention will be described based on the drawings. This embodiment is for forming an electrode pattern in a bipolar transistor.

As shown in FIG. 1(a), on an electrode metal 3 made of aluminum, for example, as a layer to be etched deposited on a semiconductor substrate 1, silicon dioxide (Si), for example, is deposited.
20) is applied. The thickness of this first mask layer 5 is a predetermined thickness.

Next, the first mask layer 5 is etched using a well-known photolithography process. As a result, the first mask N5 is left on the electrode metal 3 at intervals d of a predetermined pattern width (FIG. 2(b)).

Next, the upper surface of this electrode metal 3 and the remaining first
A second mask layer 7 made of, for example, a silicon nitride film (SIN) is formed on the mask layer 5 to a predetermined thickness h by, for example, CVD.
It is deposited and adhered by the method ((C) in the same figure). This thickness h
is smaller than the above-mentioned interval d. For example (1=2
In the case of μm, it is easy to set the armpit thickness 11 to 0.4 μn1. Further, the selection ratio of the second mask layer 7 to the electrode metal 3 is greater than the selection ratio of the second mask layer 7 to the first mask layer 5.

As a result, a side wall portion 7A of the second mask layer 7 having a constant thickness h is formed on the side wall surface 5A (δ and upper surface) of the first mask layer 5.
is deposited.

A photoresist 9, which is a third mask layer, is deposited to a predetermined thickness on the upper surface of the second mask N7, for example, by spin coating. That is, the photoresist 9 is applied so that it is deposited on the second mask N7 between the opposing sidewall portions 7A, 7A of the second mask layer 7 (FIG. 4(d)).

Thereafter, the upper surface of the photoresist 9 is etched to make it a flat surface, exposing the upper surface of the second mask layer 7 disposed on the first mask layer 5. That's right, second mask N.
The photoresist 9 is removed leaving the photoresist 9 between the side wall portions 7A and 7A of the photoresist 7 (e) in the same figure).

Then, only this second mask layer 7 is selectively removed using dry etching such as reactive ion etching. As a result, a part of the upper surface of the electrode metal 3, which is the layer to be etched, is exposed over a predetermined width (FIG. 2(f)).

This exposure width corresponds to the thickness of the side wall portion 7A of the second mask N7. The second mask N7 on the top surface of the first mask layer 5 has also been removed by etching, but the mask 7 below the photoresist 9 remains.

Then, the electrode metal 3 is etched using the first mask M5 and the photoresist 9 (a portion above the second mask N7) remaining on the electrode metal 3 as masks. As a result, in the semiconductor device 2, a plurality of electrodes 3A, 3B are formed on the semiconductor substrate 1 at intervals of a fine width h (for example, 0.4 μm).

3C, 3D, and 3E are formed ((g) in the same figure).

Note that the method of the present invention is not limited to the above-mentioned embodiments, and can also be applied to, for example, forming contact holes. In this case, the silicon dioxide film is used as the layer to be etched, for example.

<Effects of the Invention> As explained above, in the method of manufacturing a semiconductor device according to the present invention, the yield in forming thin patterns is improved, and the throughput is also improved. On the other hand, if the pattern formation is the same as conventional methods, the cost of the mask can be reduced.

0......First mask layer (silicon dioxide), 5A......Side wall, 7... Second mask layer (silicon nitride), 7A...Side wall part, 9・・・・・・・・・Photoresist (Third mask layer).

[Brief explanation of drawings]

1(a) to 1(g) are cross-sectional views for explaining each step of a method for manufacturing a semiconductor device according to an embodiment of the present invention;
Figures (a) to (c) are cross-sectional views for explaining the steps of a conventional manufacturing method of this type of semiconductor device.

Claims (1)

[Claims] (1) A first layer is placed on the layer to be etched formed on the semiconductor substrate.
a step of depositing a mask layer; a step of removing a portion of the first mask layer to leave the first mask layer on the layer to be etched at predetermined intervals; and a step of depositing a mask layer on the layer to be etched and the first mask. covering the sidewalls of the first masking layer with the sidewalls of the second masking layer by depositing a second masking layer on the layer to a thickness smaller than the spacing; and the opposing sidewalls. a step of depositing a third mask layer on the second mask layer between the parts; and a step of exposing a part of the upper surface of the layer to be etched by selectively removing the sidewall part of the second mask layer. A method for manufacturing a semiconductor device, comprising: etching a layer to be etched using the first mask layer and the third mask layer as masks.