JPH0658938B2 - Semiconductor device - Google Patents

Description

Description: (a) Technical Field of the Invention The present invention relates to a semiconductor device for memory, and more particularly to improvement of the shape of a light-transmitting plate included in a cap.

(b) Conventional technology EPROM (erasable programmable read only memor)
y) is a semiconductor memory device capable of erasing the memory by irradiating the semiconductor chip on which the memory has been written with ultraviolet rays, and the cap of the semiconductor container is provided with a transparent plate capable of transmitting the ultraviolet rays. The semiconductor chip in the container can be completely seen through the transparent plate and has a structure capable of sufficiently irradiating ultraviolet rays. A similar light-transmitting plate is also provided in the one-chip microcomputer in which the EPROM is incorporated.

FIG. 6 is an outline view of a glass-sealed EPROM.
Is a ceramic cap, 2 is a translucent plate, and 3 is a lead base for housing a semiconductor chip. The cap 1 is sealed to the lead base 3 with a low melting point glass 4. FIG. 7 is a cross-sectional view of the cap 1, and the translucent plate 2 is made of a highly translucent material such as a glass plate or a transparent quartz plate, and the inner wall of the window provided in the cap 1 and the side surface of the translucent plate 2 are shown. And are welded together, and the shape of such a conventional transparent plate is a perfect circle as shown in the figure.

However, since the degree of integration has increased and the semiconductor chip has grown in size, and strip-shaped elongated semiconductor chips have come to be used to solve problems in circuit design,
When the semiconductor chip is mounted on the lead base 3, it is necessary to increase the size of the transparent plate 2.

Therefore, when it is attempted to provide a perfect circular light-transmitting plate on the cap of the semiconductor container for accommodating such a strip-shaped semiconductor chip, there is a dimensional limitation, and an elongated rectangular transmission window as shown in FIG. 8 is provided. There must be.

However, when such a large translucent plate 22 is welded to the cap 21, the translucent plate 22 having weak mechanical strength is easily cracked due to thermal strain, and a gap is formed in the welded portion to maintain airtightness. Becomes difficult.

Therefore, the cap 21 and the translucent plate 22 are manufactured by using a material having a coefficient of thermal expansion that is as close as possible, but it is difficult to prevent the translucent plate from cracking only by selecting the material. The airtightness of the semiconductor container will be broken due to the occurrence of cracks or gaps in the welded portion.

(c) Object of the Invention The present invention proposes an improvement in the structure of a semiconductor device that can reduce the occurrence of cracks in such a large-sized light-transmitting plate and the airtight destruction of the welded portion.

(d) Structure of the Invention According to the present invention, the above object is to provide an inner wall of a rectangular window having at least four rounded corners provided in a cap made of ceramic, having the same thickness as the cap, and having the same shape as the window. The present invention is achieved by a semiconductor device characterized in that a cap, which is welded to the outer surface of a light-transmitting plate made of a light-transmitting material such as glass, is sealed on the upper surface of a lead base that houses a semiconductor chip having an EPROM. To be done.

(e) Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

FIG. 1 is an outline view of the EPROM of the first embodiment according to the present invention. As shown in the figure, a light-transmitting plate 32 made of a material having a good light-transmitting property such as a glass plate or a transparent quartz plate has an elliptical shape, and a cap 31 made of ceramic and a lead base 33 are sealed with a sealing material. .

As the adhesive material, a low melting point glass 34 having a melting point of 400 to 500 ° C. or an organic adhesive having a sealing temperature of 250 to 400 ° C. is used, and a ceramic is used as a material of the cap 31, and CERDIP is used. It is used to seal mold packages.

These sealing materials are applied to the sealing surface of the cap 31, and the cap 31 and the lead base 33 are sealed by low temperature heating.

2 is a plan view of the cap 31 and the translucent plate 32 shown in FIG. 1, and FIG. 3 is a cross-sectional structural view thereof. The elliptical window provided in the cap 31 has the same shape as the window. A transparent plate 32 having the same thickness as the cap is attached.

The translucent plate 32 of this embodiment has an elliptical shape, and since the four corners where stress is particularly likely to occur are rounded, stress is less likely to occur, and it has an excellent shape second only to a perfect circle. Since the cap 31 has the same thickness as that of the cap 31, the stress from the inner peripheral surface of the window to the outer peripheral surface of the transparent plate becomes uniform, and therefore the transparent plate is hardly cracked.

Since the inner side wall of the window of the cap 31 and the side wall of the transparent plate 32 are welded at a high temperature, they are not destroyed by heat even when sealing is performed at a low temperature.

Moreover, the EPROM having such an elliptical light-transmitting plate 32 has such a shape that the above stress is unlikely to occur.
Is significantly more reliable.

FIG. 4 is a plan view of the cap 41 and the light transmitting plate 42 of the second embodiment according to the present invention. The light transmitting plate 42 provided on the cap 41 is a rectangle having semicircular ends.

In order to embed the elliptical light-transmitting plate in the window provided in the rectangular cap, it is necessary to widen the width of the cap. When the width of the cap is narrow, the strength of the cap may decrease. However, if you use a rectangular translucent plate with semicircular ends, you do not have to worry about it.

FIG. 5 is a plan view of a cap 51 and a light-transmitting plate 52 according to a third embodiment of the present invention. The light-transmitting plate 52 provided on the cap 51 is a rectangle having rounded corners of radius R at its four corners. . When the width of this rectangle is L, the concentration of stress can be prevented by setting the dimension of R to 1/10 or more of L. When embedding a translucent plate having such a shape in the window of the cap, after welding the contact surface between the translucent plate and the cap at about 1,100 ° C., the opaque translucent material which is the material of the translucent plate is welded. A heat treatment at about 900 ° C. is performed to make the optical glass transparent, and the welding of the transparent plate and the cap is completed.

(f) Effects of the Invention As is clear from the above description, according to the present invention, in the EPROM or the one-chip microcomputer in which the light transmitting plate is enlarged, the occurrence of cracks in the light transmitting plate and the airtight destruction of the welded portion are reduced. As described above, it becomes possible to weld the cap and the transparent plate, which greatly contributes to the improvement of the quality of the semiconductor device.

[Brief description of drawings]

FIG. 1 is an external view of an EPROM according to the first embodiment of the present invention, FIG. 2 is a plan view of a cap according to the first embodiment of the present invention, and FIG. 3 is a cap of the first embodiment according to the present invention. 4 is a plan view of the cap of the second embodiment according to the present invention, FIG. 5 is a plan view of the cap of the third embodiment according to the present invention, and FIG. 6 is the outline of a conventional EPROM. Fig. 7 is a sectional view of a conventional cap, and Fig. 8 is a plan view of a conventional cap. In the drawing, 1,21 is a conventional cap, 2,22 is a conventional transparent plate, 3,33 is a lead base, 4,34 is a low-melting glass, 31,41,51 are caps of the examples according to the present invention, Reference numerals 32, 42 and 52 denote translucent plates according to the embodiments of the present invention.

Claims (1)

[Claims] 1. An inner wall of a rectangular window provided on a cap made of ceramic and having at least four rounded corners,
A cap having the same thickness as the cap and the window and the outer surface of a light-transmitting plate made of a light-transmitting material such as glass having the same shape is welded to the upper surface of the lead base for housing the semiconductor chip having the EPROM. A semiconductor device characterized by being worn.