JPH0574935B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a supporting substrate for a semiconductor device constructed using a semiconductor material such as silicon, and in particular to a method for manufacturing a molybdenum substrate used as a supporting substrate. Regarding the method.

[Prior Art] Semiconductor devices such as diodes and thyristors generally have a structure in which external lead electrodes can be taken out from the mutually opposing main surfaces of a semiconductor pellet. On the other hand, since semiconductor pellets have low strength and are brittle, they are supported by a metal substrate during use. Molybdenum, which has a coefficient of thermal expansion close to that of the semiconductor material, is used as the metal substrate material for supporting the semiconductor pellets.

A molybdenum plate used as a semiconductor support substrate is generally manufactured from a molybdenum material plate by a punching process. This type of molybdenum plate is commercially available in the form of small circular or square pieces.
The user places a semiconductor pellet on the small piece by applying a brazing material or the like as necessary, and assembles a semiconductor device.

The rolled molybdenum material plate is punched using a die steel or a carbide mold to form a circular or square molybdenum plate piece.

Since such a molybdenum material plate has a layered fiber structure extending in a direction perpendicular to the punching direction, peeling is likely to occur during punching. Furthermore, during punching, cracks are likely to occur along the grain boundaries of the layered structure, resulting in serious defects (here, such cracks along the grain boundaries of the layered structure are referred to as lamination cracks). ).
When lamination cracks occur, the properties of the substrate as a semiconductor supporting substrate are significantly impaired. Therefore, conventionally, in order to prevent lamination cracks from being mixed in, a molybdenum plate was etched using a mixed acid such as hydrofluoric acid, nitric acid and acetic acid, and then inspected using a magnifying glass.

However, even if conventional etching is performed, lamination cracks are often not eliminated, and the properties of the substrate as a semiconductor supporting substrate are significantly impaired.

[Purpose of the invention]

An object of the present invention is to provide a method of manufacturing a molybdenum plate for supporting semiconductors by punching from a molybdenum material plate without producing lamination cracks.

[Structure of the invention]

The present invention relates to a method for manufacturing a molybdenum substrate used to support semiconductor materials, in which a molybdenum material plate is rolled and has a c-Vickers hardness of 220 to 250, with a thickness of 0.02 to 250. A method for manufacturing a molybdenum plate for semiconductor substrates in which the molybdenum plate for semiconductor substrates is punched using a mold having a clearance of 0.05, or a molybdenum plate that has been subjected to rolling processing and has a Vickers hardness of 220 to 250. This is a method for manufacturing a molybdenum plate for semiconductors, in which punching is performed at a temperature exceeding 300°C using a mold having a clearance of 0.02 to 0.05 with respect to the plate thickness.

[Embodiments of the invention]

The present invention will be explained below with reference to embodiments shown in FIGS. 1 to 3. (In this example, the molybdenum material plate subjected to rolling processing is simply referred to as a molybdenum material plate.) Example 1 First, each material has a Bitkers hardness (Hv) of 220~
Molybdenum material plates with a size of 250, 260 or more, and 200 or less and a thickness of 1.0 mm were prepared. These three types of molybdenum material boards are compared to the thickness of this molybdenum material board.
Using a mold with a clearance of 0.035mm,
Punching temperature 300~800℃, punching speed 80~90
1000 disc-shaped molybdenum substrates each having a diameter of 24 mm were produced by punching at a speed of mm/sec (Sample 1). Further, using molybdenum material plates having the same Vickers hardness and thickness as above, 1000 molybdenum substrate samples 2 and 2 were obtained for each Vickers hardness under the above punching conditions.

These samples 1 to 3 were examined to determine whether or not lamination cracks had occurred, and the incidence of lamination cracks for each sample was determined. The results are shown in FIG. As shown in Fig. 1, when the Vickers hardness is 220-250 for samples 1 and 2, there is no occurrence of lamination cracks, and for sample 3, when the Vickers hardness is 220-250, no lamination cracks occur. The incidence is extremely small at 0.01%. On the other hand, when the Bitkers hardness becomes less than 200, the Bitkers hardness decreases.
Compared to 220-250, the incidence of lamination cracks slightly increased, and the Vickers hardness was 260.
It can be seen that the occurrence rate of lamination cracks increases dramatically when the temperature exceeds this level.

Next, the Bitkers hardness is 220 to 250, respectively.
A molybdenum material plate with a size of 260 or more and 200 or less and a thickness of 0.5 mm was prepared. These three types of molybdenum material boards are 0.02% of the thickness of this molybdenum material board.
Using a die with a clearance of mm, punching was performed at a punching temperature of 300 to 700°C and a punching speed of 84.7 mm/sec to produce 2000 disk-shaped molybdenum substrates each with a diameter of 13.5 mm (Sample 4). .
Furthermore, 3000 molybdenum substrate samples 5 and 6 were obtained in the same manner using molybdenum material plates having each of the above-mentioned Vickers hardnesses.

These samples 4 to 6 were examined to determine whether or not lamination cracks had occurred, and the incidence of lamination cracks for each sample was determined. The results are shown in Figure 1. 1st
As shown in the figure, when the Vickers hardness was 220 to 250 for Samples 4 to 6, there was no incidence of lamination cracks.

Example 2 The incidence of lamination cracks when the punching temperature is varied will be explained with reference to FIG.

Bitkers hardness is 220-250 and 260 or more, respectively.
A molybdenum material plate of 200 or less and a plate thickness of 1.0 mm was prepared. These three types of molybdenum material plates were punched using a die with a clearance of 0.02 mm to the thickness of these molybdenum material plates, and the temperature was controlled.
Punching was performed at a punching speed of 84.7 mm/sec at three stages of 300°C or lower, 300 to 600°C, and 600 to 800°C, and a disk-shaped molybdenum substrate with a diameter of 24 mm was punched at 1000°C for each punching temperature. Made individually. In addition, in Figure 2, sample 7 is a molybdenum plate with a Bitkers hardness of 200 or less, and Sample 7 is a molybdenum plate with a Bitkers hardness of 260.
The above molybdenum plate is sample 8, Bitkers hardness
Sample 9 is a molybdenum plate of 220 to 250.

As is clear from Figure 2, for sample 9
No lamination cracks were observed in all temperature ranges of 300°C or lower, 300 to 600°C or lower, and 600 to 800°C. Regarding sample 8, lamination cracks were observed in the temperature range of 300°C or lower, but no lamination cracks occurred in the temperature ranges of 300 to 600°C and 600 to 800°C. For sample 7, the punching temperature was 300℃
Considerable occurrence of lamination cracks was observed below, but it decreased rapidly between 300 and 600℃, and
No flashes occurred at ~800°C.

Example 3 Bitkers hardness is 220-250 and plate thickness is 1.0mm
A molybdenum material board was prepared. This molybdenum material plate was punched at a temperature of 300°C using a mold having clearances of 0.02 or less, 0.02 to 0.05, and 0.06 to 0.1 relative to the thickness of the molybdenum material plate.
Punching was carried out at ~800°C and a punching speed of 84.7 mm/sec to produce 10,000 disc-shaped molybdenum substrates with a diameter of 24 mm for each of the above molds (Sample 10).
Further, in the same manner, using a molybdenum material plate with the above-mentioned Bitkers hardness, for each mold, an additional 10,000
Sample 11 was prepared by producing individual molybdenum substrates.

Samples 10 and 11 were examined to see if lamination cracks were occurring, and the incidence of lamination cracks was determined for each sample. The results are shown in Figure 3.
As is clear from Figure 3, 0.02mm or less and 0.06~
When punching is performed using a die with a clearance of 0.1 mm, the incidence of lamination cracks is extremely high. On the other hand, when a mold having a clearance of 0.02 to 0.05 mm was used, no lamination cracks were observed.

In addition, the Bitkers hardness is 220 to 250 and the plate thickness is
A 0.5 mm molybdenum material plate was prepared. This molybdenum material plate was punched using a mold having clearances of 0.02 or less, 0.02 to 0.06, and 0.05 to 0.1 with respect to the thickness of the molybdenum material plate, at a temperature of 300 to 800°C and a punching speed of 84.7 mm/sec. 10,000 disk-shaped molybdenum substrates with a diameter of 13.5 mm were produced by punching for each of the above molds (Sample 12). Furthermore, in the same manner, 10,000 molybdenum substrates were manufactured for each mold using the molybdenum material plates with the above-mentioned Bitkers hardness, and samples were prepared.
It was set at 13.

These samples 12 and 13 were examined to determine whether or not lamination cracks occurred, and the incidence of lamination cracks was determined for each sample. The results are shown in Figure 3. As shown in FIG. 3, when punching is performed using a die having a clearance of 0.02 mm or less or 0.06 to 0.1 mm, the incidence of lamination cracks is extremely high. On the other hand, when a mold having a clearance of 0.02 to 0.05 mm was used, no lamination cracks were observed.

As is clear from Examples 1 to 3 above, when manufacturing a molybdenum substrate by punching a molybdenum material plate with a Bitkers hardness of 220 to 250, the thickness of the molybdenum material plate is
If a die with a clearance of 0.02 to 0.05 is used for punching, lamination cracks will not occur in the molybdenum substrate.

In addition, when manufacturing a molybdenum substrate by punching a molybdenum material plate with a Bitkers hardness outside the range of 220 to 250, a mold having a clearance of 0.02 to 0.05 with respect to the thickness of the molybdenum material plate is used. Therefore, if the punching process is performed at temperatures above 300°C, lamination cracks will hardly occur.

〔Effect of the invention〕

As explained above, if the method for manufacturing a molybdenum substrate according to the present invention is used, lamination cracks will not occur in the molybdenum plate and the yield of the product will be extremely high.

[Brief explanation of drawings]

Figure 1 shows the relationship between Vickers hardness and the incidence of lamination cracks, Figure 2 shows the relationship between punching temperature and the incidence of lamination cracks, and Figure 3 shows the relationship between the punching temperature and the incidence of lamination cracks. FIG. 3 is a diagram showing the relationship between the mold clearance and the incidence of lamination cracks.

Claims (1)

[Claims] 1. In a method for manufacturing a molybdenum substrate used to support a semiconductor material, a molybdenum material plate that has been subjected to a rolling process and has a Vickers hardness in the range of 220 to 250 is used in accordance with the thickness of the molybdenum material plate. hand
1. A method for manufacturing a molybdenum plate for a semiconductor substrate, characterized in that punching is performed using a mold having a clearance of 0.02 to 0.05. 2. In a method for manufacturing a molybdenum substrate used to support a semiconductor material, a molybdenum material plate that has been subjected to rolling processing and has a Vickers hardness of 220 to 250 has a hardness of 0.02 to 0.05 relative to the thickness of the molybdenum material plate. A method for manufacturing a molybdenum plate for semiconductor substrates, characterized in that punching is performed at a temperature exceeding 300°C using a mold having a clearance.