JPH0685056A - Manufacture of mesa type semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing the mesa type semiconductor device in which the insulation film formed at the shoulder of it is farmed so that it is not lower than the surface of a semiconductor substrate and sufficient voltage-resistance is obtained. CONSTITUTION:When a recessed section is formed on a semiconductor wafer for forming a shoulder part of mesa type, a spacer film 4 consisting of a resist film, etc., is coated on the surface of a semiconductor wafer 3 in advance, and then a recessed section 6 is formed by etching the semiconductor wafer together with the spacer film, and further, a glass slurry liquid 7 is poured into the recessed section for baking. By this, the spacer film is burned out, so that the insulation film (glass part 7a) higher than the surface of the semiconductor substrate is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mesa type semiconductor device. More specifically, the present invention relates to a method for manufacturing a semiconductor device in which a shoulder insulating film of a mesa type semiconductor device is improved and is electrically insulated more effectively (hereinafter, simply referred to as insulation).

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a mesa type semiconductor device has a pn junction surface 55 on a side portion of a semiconductor substrate 51 thereof.
In order to maintain the insulation of the above, an inclined surface 52 is formed on the shoulder of the upper end portion, and an insulating film 53 such as glass is formed on the inclined surface. Since the insulating film 53 applied to the inclined surface 52 is thin and shrinks during firing, it is usually present at a position below the main surface 54 of the substrate 51. Therefore, the length of the insulating film 53 is short, and when voltage is applied to both upper and lower surfaces during use, the substrate 51
Leakage easily occurs between the upper and lower electrodes through the surface of the insulating film 53.

The reason why only the insulating film 53 having such a shape can be formed is due to the following manufacturing method.

That is, as shown in FIG.
In the process, for example, an etching protection film 62 made of a black mask or the like formed on the main surface of the silicon wafer 61 composed of the p layer 61a and the n layer 61b by a printing method or the like.
Patterning is performed.

Then, in step b, etching is performed with an etching solution so that the recess 63 is formed in the silicon wafer 61, and then the etching protection film 62 is removed with an organic solution.

Then, in step c, a glass slurry liquid 64 is injected into the recess 63 of the silicon wafer 61. As the glass slurry liquid 64, a mixture of powder such as powdered glass and alcohol is used. Then, the glass slurry liquid 64 is fired by heating.

In step d, the silicon wafer 61 is diced at the center of the fired glass portion 64a (the alternate long and short dash line in the drawing indicates the cutting line), so that the mesa shape of the shape shown in FIG. 3 is obtained. A semiconductor device can be obtained. The glass portion 64a constitutes the insulating portion 53.

According to such a manufacturing method, the insulating portion 53 is formed only below the upper surface of the substrate 51 because it shrinks during firing of the glass slurry liquid, and the thickness of the insulating portion 53 becomes thin. The distance of the surface of the insulating film 53 to reach (different potential when used) is shortened.

[0009]

In the mesa type semiconductor device manufactured by the conventional manufacturing method, the insulating effect is not sufficient. That is, the voltage applied between the electrode formed on the main surface 54 of the substrate 51 and the electrode formed on the lower surface is held via the insulating film 53, but the distance is short, so the insulating film
It is easy to leak through the surface of 53. As a result, there is a problem that the defect rate as a product of the semiconductor device increases, the cost increases, and the reliability also decreases.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a mesa type semiconductor device having an insulating film having a dramatically improved insulating effect.

[0011]

The manufacturing method of the present invention comprises (a)
A spacer film is formed on the main surface of the semiconductor wafer, (b) the upper surface thereof is patterned by an etching protection film, and (c) etching is performed so that a recess is formed on the main surface of the wafer. d) Then, the etching protection film is removed, and (e) a glass slurry liquid is injected into the recess so as to substantially reach the surface of the spacer film, and (f)
Then, the wafer is heated to remove the spacer film and fire the glass, and (g) dicing is performed on the fired glass portion.

[0012]

According to the manufacturing method of the present invention, when the glass slurry liquid is injected into the recess of the wafer, it can be injected to a position higher than the upper surface of the wafer by the thickness of the spacer film. Then, after the glass is baked and the spacer film is removed, the glass portion is formed in a state of protruding on the upper surface of the wafer. As a result, in the mesa-type semiconductor device obtained by dicing the wafer, the insulating film (the glass portion) is thick and has a shape protruding from the upper surface of the wafer. Therefore, the surface distance from the upper end to the lower end of the insulating film is increased. Is much longer than the conventional one.

Therefore, the insulation between the upper layer and the lower layer of the substrate having different potentials due to the pn junction during use can be effectively maintained.

[0014]

The manufacturing method of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a process diagram showing an embodiment of the manufacturing method of the present invention, and FIG. 2 is a sectional view showing an example of a mesa type semiconductor substrate manufactured by the manufacturing method of FIG.

In step a of FIG. 1, first, a photoresist film 4 is applied onto the main surface of a wafer 3 on which ap layer 1 and an n layer 2 have been formed (p layer and n layer may be reversed). To do. The photoresist film 4 is a kind of the spacer film in the claims, and is not particularly limited to the photoresist film, and may be any one that is easily corroded by the etching solution and burns off at the firing temperature. .

Then, in step b, the upper surface of the photoresist film 4 is masked by an etching protection film 5 patterned by screen printing. The etching protection film 5 is made of, for example, coal tar which is not easily dissolved by acid.

Then, in step c, etching is performed with a nitric acid solution so that the recess 6 is formed on the upper surface of the wafer 3. As this etching liquid, an etching liquid suitable for the type and purpose of the semiconductor is used.

In step d, the etching protection film 5 formed in step b is removed, and then the glass slurry liquid 7 is injected into the recess 6 formed through the photoresist film 4 to the wafer 3. . As in the conventional manufacturing method, as the glass slurry liquid, a mixture of powder such as powdered glass and alcohol is used, and it is injected up to the vicinity of the upper surface of the photoresist film 4.

In step e, the glass slurry liquid is fired by heating the wafer into which the glass slurry liquid has been injected. By this heating, the photoresist film 4 is simultaneously burned and removed. The fired glass portion 7a contracts slightly as shown in the figure, and its cross section becomes like a heart shape. Next, a semiconductor chip is formed by dicing the center portion of the baked glass portion 7a (the dashed line in the drawing indicates a cutting line), and by providing electrodes and the like, the cross-sectional shape shown in FIG. A mesa type semiconductor device (electrodes and the like are not shown) can be obtained.

In FIG. 2, the same reference numerals are used for the same components as in FIG. However, the glass portion 7a in step d of FIG. 1 is called the insulating film 9 in FIG.
In FIG. 2, reference numeral 10 denotes a pn junction surface formed on the semiconductor substrate, and the insulating film 9 is formed so as to cover the side surface portion of the substrate 8 just corresponding to the pn junction surface 10 and from the upper surface of the substrate 8. It is thicker as it protrudes upward. This protrusion 9
The formation of a is due to the fact that the glass slurry liquid 7 shown in step d of FIG. By thus projecting and being thickly formed, the distance on the surface of the insulating portion 9 from the p layer 1 to the n layer 2 of the substrate 8 is much longer than that of the conventional insulating portion 53 (see FIG. 3). It has become a thing.

The substrate 8 having such a structure has an extremely excellent insulation performance between the p layer 1 and the n layer 2, and since the insulating film 9 is thick, the electrostatic withstand capability is also improved.

[0023]

According to the manufacturing method of the present invention, since it is possible to easily manufacture a mesa type semiconductor device having an excellent insulating performance, it is possible to significantly reduce the defective rate of semiconductor products.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view showing an example of a mesa type semiconductor device manufactured by the manufacturing method of FIG.

FIG. 3 is a cross-sectional view showing an example of a conventional mesa type semiconductor device.

FIG. 4 is a process drawing showing an example of a method for manufacturing the mesa semiconductor device of FIG.

[Explanation of symbols]

 3 Semiconductor Wafer 4 Photoresist Film 5 Etching Protective Film 6 Recess 7 Glass Slurry Liquid 7a Glass Part 8 Substrate 9 Insulating Film

Claims (1)

[Claims] 1. A spacer film is formed on a main surface of a semiconductor wafer, and a pattern is formed on the upper surface of the spacer film by an etching protection film, and a recess is formed on the main surface of the wafer. Etching is performed as follows, (d) then the etching protection film is removed, (e) a glass slurry liquid is injected into the recess so as to substantially reach the surface of the spacer film, and (f) then the wafer. The spacer film is removed and the glass is baked by heating the
(G) A method for manufacturing a mesa-type semiconductor device, which comprises dicing the baked glass portion.