JPH08124879A - Manufacture of mesa semiconductor device - Google Patents

Abstract

PURPOSE: To enable more mesa semiconductor devices than in prior art to be easily manufactured per one wafer. CONSTITUTION: After a P-type semiconductor region 11 is formed on the upper surface of an N-type semiconductor substrate 12 as shown in (b), cut-grooves 17 with width W1 and depth D1 as shown in (c) are formed by dicing. Then, through etching using a resist film, mesa grooves 14 with width W2 and depth D2 are formed longitudinally and transversely to divide the P-type semiconductor region 11 and the N-type semiconductor substrate 12 by respective devices as shown in (d), glass 15 is injected in the mesa grooves 14 as shown in (e) and baked at about 700 deg.C, and a glass passivation film 15a is formed in the mesa grooves 14 to cover exposed PN junction parts 13 as shown in (f). Finally, by dicing at the center lines of the mesa grooves 14 from the top of the glass passivation film 15a as shown by dotted lines, this is separated into individual semiconductor devices 16 as shown in (g).

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, and more particularly to a method for forming a mesa groove.

[0002]

2. Description of the Related Art Conventionally, in the case of forming a semiconductor device such as a diode or a transistor having a high voltage withstand voltage and a high frequency characteristic, it is formed by a manufacturing method as shown in FIG. 2A shows a state of the wafer viewed from the upper surface, and FIGS. 2B to 2E show cross-sectional shapes when the FIG. 2A is cut along Z3-Z4. 2F shows a sectional shape when the wafer of FIG. 2A is separated into individual semiconductor elements.

A manufacturing method will be described. The semiconductor element in FIG. 2 is formed by forming a P-type semiconductor region 11 on the upper surface of an N-type semiconductor substrate 12 as shown in FIG. 2), a groove (hereinafter referred to as a mesa groove) 14 for separating the P-type semiconductor region 11 and the N-type semiconductor substrate 12 into respective element units is formed vertically and horizontally with a width W3 and a depth D3. As shown in FIG. 2D, the glass 15 is injected into the mesa groove 14 and baked at a temperature of about 700 ° C., and the glass is formed so as to cover the PN junction 13 exposed in the mesa groove 14 as shown in FIG. The protective film 15a is formed. Finally, the central portion (the portion indicated by the dotted line) of the mesa groove 14 is scribed and cut from above the glass protective film 15a with a dicer or the like to separate into individual semiconductor elements 16 as shown in FIG. 2 (f). Individual semiconductor devices are completed by assembling by sealing with resin or the like.

[0004]

In the method of manufacturing a semiconductor device described above, when the mesa groove 14 is formed by etching,
Since the etching is performed not only in the depth direction of the groove but also in the lateral direction, the width W of the mesa groove 14 is larger than that of the isolation region (called a scribe line) of the semiconductor element having no mesa groove 14.
Since it is necessary to take 3 wide, there is a problem that the chip size becomes large and the number of semiconductor elements 16 that can be formed on one wafer 10 becomes small. In particular, when forming a high breakdown voltage semiconductor device, it is necessary to make the depth D3 of the mesa groove 14 deeper, so that the width W3 of the mesa groove 14 becomes wider and the chip size becomes larger. There was a problem that the number would be even smaller.

Therefore, the present invention solves these problems and adds a simple manufacturing process to increase the width W3 of the mesa groove 14.
By making it possible to obtain a mesa-type semiconductor device in which only the depth D3 of the mesa groove 14 is made deeper than before in order to improve the electrical characteristics of the mesa-type semiconductor device and reduce the chip size, It is an object to increase the number of wafers to be taken per wafer 10.

[0006]

In order to solve the above problems, a method of manufacturing a mesa type semiconductor device according to a first aspect of the present invention is a method of manufacturing a semiconductor device having a mesa groove for separating a PN junction. In the method, the mesa groove is etched after the cut groove is formed in advance in the portion to be the mesa groove. Further, the method of manufacturing a mesa type semiconductor device according to a second aspect is characterized in that the depth of the cut groove is not more than half the thickness of the wafer.

[0007]

According to the method of manufacturing the mesa type semiconductor device of the present invention, only the depth of the mesa groove can be increased without increasing the width of the mesa groove.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a mesa type semiconductor device which is an embodiment of the present invention will be described in detail below with reference to FIG.
In the present specification, the same or similar parts will be denoted by the same reference symbols throughout the drawings. FIG. 1 shows an outline of a method for manufacturing a mesa type semiconductor device of the present invention, and FIG.
1B shows a state of the wafer viewed from above, FIGS. 1B to 1F show sectional shapes when the wafer 10 of FIG. 1A is cut along Z1-Z2, and FIG. Shows a sectional shape when the wafer 10 of FIG. 1A is separated into individual semiconductor elements 16. Note that, in FIG. 1A, for the sake of explanation, the ratio of the sizes of the semiconductor elements 16 and the mesa grooves 14 is enlarged and schematically represented.

The manufacturing method will be described. The semiconductor device shown in FIG. 1 is formed by forming a P-type semiconductor region 11 on the upper surface of an N-type semiconductor substrate 12 as shown in FIG. ) Grooves shown below (hereinafter referred to as cut grooves)
17 is formed to have a width of W1 and a depth of D1 in the vertical and horizontal directions as shown in FIG. 1A, and then is etched using a resist film (not shown) to form P as shown in FIG.
A groove (hereinafter referred to as a mesa groove) 14 for separating the n-type semiconductor region 11 and the n-type semiconductor substrate 12 into respective element units is formed vertically and horizontally with a width of W2 and a depth of D2, as shown in FIG. Then, glass 15 is injected into the mesa groove 14 and baked at a temperature of about 700 ° C., and the PN exposed in the mesa groove 14 as shown in FIG.
The glass protective film 15a is formed so as to cover the bonding portion 13. Finally, the central portion (the portion indicated by the dotted line) of the mesa groove 14 is cut by dicing from above the glass protective film 15a, and the individual semiconductor elements 1 as shown in FIG.
Individual semiconductor devices are completed by separating into 6 and assembling by sealing with epoxy resin or glass.

In the above-described manufacturing method, since the cut groove 17 is formed in advance and then the mesa groove 14 is etched, it becomes the same as that in which the depth direction is larger than the width direction in advance. If the etching is performed, the mesa groove 14 which is deeper than the conventional one by the depth of the cut groove 17 is formed only in the depth direction. The glass protective film 15a has a function of preventing water and other unnecessary conductive substances from adhering to the PN junction 13 and generating a leak current in the semiconductor element.

The width W1 of the cut groove 17 is determined by the thickness of the tooth (blade) for dicing, and is about 3 in this embodiment.
It is 0 μm. Further, in order to prevent the mechanical strength of the wafer 10 from being significantly reduced due to the formation of the cut groove 17 and the wafer 10 from being cracked or chipped during manufacturing, the depth D1 of the cut groove 17 and the depth D2 of the mesa groove 14 are prevented. Is wafer 1
It is preferable to form it to a depth of about several tens of μm to 200 μm, which is less than half of the thickness of 0, and is about 40 μm in this embodiment.
And In order to keep the depth D1 of the cut groove 17 constant, the size of the blade should be measured at appropriate times for each wafer, before and after dicing, or the depth of the cut groove 17 should be measured by laser light or the like to determine the position of the blade. Should be adjusted. Further, it is more effective to use a wafer having a crystallographic direction such that the etching rate in the depth direction is higher than the etching rate in the lateral direction, because it is not necessary to make the depth of the cut groove 17 too deep.

In this embodiment, the mesa groove 14 is etched using a resist film (not shown) after the dicing, but the dicing may be performed after the resist film is formed.

[0013]

As described above in detail, according to the present invention, it is possible to obtain a mesa-type semiconductor device in which only the depth D2 of the mesa groove is increased without increasing the width W2 of the mesa groove 14 as compared with the conventional case. As a result, it becomes possible to form mesa-type semiconductor devices such as diodes and transistors having good withstand voltage and high frequency characteristics while increasing the number of wafers per wafer as compared with the conventional manufacturing method. There is an effect that the cost of the element 16 can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic flow of a manufacturing method of the present invention.

FIG. 2 is an explanatory diagram showing a schematic flow of a conventional manufacturing method.

[Explanation of symbols]

 10: Semiconductor wafer 11: P-type semiconductor region 12: N-type semiconductor substrate 13: Bonding part 14: Groove (mesa groove) 15a: Glass protective film 16: Individual semiconductor element 17: Cut groove

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device having a mesa groove for separating a PN junction, wherein a cut groove is formed in advance in a portion to be a mesa groove, and then the mesa groove is etched. Manufacturing method of mesa type semiconductor device. 2. The method of manufacturing a mesa type semiconductor device according to claim 1, wherein the depth of the cut groove is not more than half the thickness of the wafer.