JPS5994821A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To form a semiconductor element whose back-side electrode is excellent in the adhesion and stable in the same way as the surface electrode thereof, by leaving a back-side oxide film as it is until the back-side electrode is just formed, and by using said film for protection. CONSTITUTION:In the process wherein a number of PN junctions are formed on one silicon plate and, after electrodes are connected on both surfaces, the plate is divided into a number of diodes, a high-density N<+> layer 2 is formed on the whole of one surface of an N type silicon substrate, and further oxide films 3 and 4 are formed on both surfaces of the substrate by a thermal oxidation method, for instance. Next, the whole surface of the back-side oxide film 4 is covered with pitch 5, and a part of the region of the surface oxide film 3 is removed by a photoetching method. Then, the pitch 5 on the back side is removed, a P layer 6 is formed by diffusing an impurity such as boron, for instance, through a window opened in the surface oxide film 3, and an anode electrode 7 is connected by the evaporation of aluminum, or the like. Subsequently, the surface being covered with pitch or the like, the back-side oxide film 4 is removed by etching or the like, and a cathode electrode 8 is provided in the place wherefrom the film 4 is removed. lastly the plate is cut at the middle of each P-N junction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor element having electrodes on the entire surface of one surface of a semiconductor substrate and in a predetermined region on the other surface.

For example, in the case of manufacturing planar semiconductor devices, the back side of the device generally tends to be managed more roughly than the front side of the device. However, there are problems such as contamination of the solid surface of the wafer from the support stand, etc., and adverse effects on the adhesion between the semiconductor substrate and the electrode, such as peeling of the electrode after the back electrode is attached.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor element in which not only the front electrode but also the back electrode have good and stable adhesion by eliminating the above-mentioned drawbacks.

The purpose of this is to coat both sides of a semiconductor substrate with a high concentration impurity-containing layer on the entire negative side, remove a predetermined area of the oxide film on the other side, diffuse impurities into that area, and then coat the entire surface with an oxide film. This is accomplished by removing the oxide film of the area and depositing electrodes on the - side and the other side of the region.

In the present invention, the oxide film on the back side was also removed at the same time when removing a predetermined area on the front side of the oxide film formed on both sides of the semiconductor substrate for forming the front electrode. This is based on the idea that the oxide film on the back side is left and used for protection.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 (A) to tC) shows a large number of PNs on one silicon plate.
A part of the process of forming a junction, depositing electrodes on both sides, and then dividing it to produce a large number of diodes is shown. 1st figure)
As shown in FIG. 1, a high concentration N+ layer 2 is formed on one surface of an N-type silicon substrate 1, and oxide films 3 and 4 are further formed on both surfaces by, for example, a thermal oxidation method. Next, in FIG. 2(B), the entire surface of the back oxide film 4 is covered with a pitch 5, and a part of the front oxide film 3 is removed by photo-etching. In FIG. 2(C), the pin on the back side.

Then, an impurity such as boron is diffused through the window of the surface oxide film 3 to form a second layer 6, and an anode electrode 7 is deposited by vapor deposition of aluminum or the like. Next, after covering the surface with pitch or the like, the backside oxide film 4 is removed by etching or the like, and then a hecathode electrode 8 is provided as shown in FIG. By covering the exposed portion of the PN junction with the oxide film 3, a large number of planar diode chips having an anode electrode 7 and a cathode electrode 8 on both sides can be obtained.

As described above, in the present invention, by leaving an oxide film on the back surface before forming the back electrode, it is possible to protect the back surface from contamination during the process up to that point, and the back surface is physically, chemically and stably stabilized. Since this state is maintained, peeling of the back electrode does not occur, and the effect of very good contact between the semiconductor and the electrode can be obtained.

Of course, the present invention is not limited to the diodes of the above embodiments, but can be effectively applied to the manufacture of a wide variety of semiconductor devices such as transistors and ICs.

[Brief explanation of the drawing]

FIGS. 1(A) to 1(D) are cross-sectional views showing a part of a diode manufacturing process according to an embodiment of the present invention. 1...Silicon substrate, 2...10 N layers, 3.4...Oxide film, 7...Surface electrode (anode), 8...Back surface electrode (cathode).

Claims (1)

[Claims] 1) When manufacturing a semiconductor element having electrodes on the entire surface of one surface of a semiconductor substrate and a predetermined region on the other surface, an oxide film is coated on both surfaces of the semiconductor substrate that has a highly concentrated impurity-containing layer on the entire surface of the negative surface. A semiconductor device characterized in that a predetermined region of an oxide film on a surface is removed, an impurity is diffused into the region, the oxide film on one surface is removed, and an electrode is deposited on the - surface and the other surface of the region. manufacturing method.