JPH0616515B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention mainly relates to a power semiconductor device and a method for manufacturing the same, and in particular, the mechanical strength of a semiconductor pellet is reinforced, and creeping discharge is prevented. For example, the present invention relates to a semiconductor device of a type in which an insulator or an insulator is attached to the outer peripheral edge of a semiconductor pellet and a method for manufacturing the same.

(Prior Art) When applying an encapsulating agent to the peripheral portion of a semiconductor pellet of a power semiconductor device or the like, an insulator such as silicone rubber is used for the purpose of reinforcing mechanical strength, preventing creeping discharge, etc.
A method of sticking semiconductor pellets to this via an encapping agent is used. FIG. 13 shows a cross-sectional view of this conventional semiconductor device. In this semiconductor device, an encapsulating agent (for example, an adhesive heat-curable liquid silicone rubber) is applied to a ring-shaped first insulator 1 made of silicone rubber, and the semiconductor pellets 2 are placed on the first insulator so that their mutual positions are fixed. After being determined and then filled with the encapsulation agent 3, the encapsulation agent is heated and cured to be manufactured.

In the conventional method for manufacturing a semiconductor device, when the above-mentioned encapsulation agent is filled, a part 4 of the encapsulation agent flows out between the bottom surface of the semiconductor pellet and the first insulator. When this is left as it is and the electrode is assembled and pressure-welded,
As shown in the figure, the outflowing encapping agent 4 may be sandwiched between the pressure contact electrode 5 and the pellet 2 to deteriorate the electrical characteristics or destroy the pellet. Further, when the encapsulating agent flows out, the encapsulating agent on the surface of the pellet, which should be originally applied, becomes thin, or a part of the encapsulating agent is not applied. For this reason, the emcapsulation agent 4 that protruded
Was cut off at the end, but it is a problem in manufacturing process control such as encapsulation waste.

(Problems to be Solved by the Invention) In the conventional semiconductor device in which the first insulator of silicone rubber is fixed to the semiconductor pellet through the encapsulating agent and the manufacturing method thereof, the above-mentioned method is used when the encapsulating agent is filled. In addition, the encapsulation agent flows out and adheres to the main surface of the chip, which becomes a problem when the pressure contact electrode is attached, and the removal of the outflowing encapsulation agent is also a problem in process control. Further, if the encapsulating agent flows out or the filling amount is adjusted, the encapsulating agent applied to the tip bevel surface becomes thin, or the unapplied portion is formed to reduce the surface protection effect, or the pellet and the first insulator May peel off.

An object of the present invention is to prevent the encapsulating agent from flowing into the pressure contact region between the main surface of the semiconductor pellet and the electrode post when the encapsulating agent is filled, and the encapsulating agent is firmly fixed to the semiconductor pellet. In order to satisfy the functions of the insulator and the encapsulating agent, the semiconductor pellet and the first
It is an object of the present invention to provide a semiconductor device which can be filled with a sufficient amount of an encapping agent between an insulator and a manufacturing method thereof.

[Structure of the Invention] (Means and Actions for Solving Problems) In order to solve the problems, according to the present invention, the shape of the first insulator is used in the semiconductor device, and the encapsulating agent is used in the manufacturing method. Each method is improved. That is, the first insulator of the semiconductor device of the present invention is an annular insulator made of silicone rubber or the like, and is in contact with the main surface of the semiconductor pellet along the inner peripheral edge of the main surface and faces the side wall of the pellet. And has a protruding portion surrounding the pellet main surface, the first insulator terminal portion located further inside than the portion in contact with the pellet main surface has a gap between the pellet main surface and the pellet main surface. A second insulating material (hereinafter referred to as an encapsulating agent) filled with a space formed between the first insulator and the pellet main surface from the outer peripheral edge to a portion in contact with the first insulator inside the outer peripheral edge. The outer peripheral edge of the pellet is surrounded by a U-shape, and the first insulator is shaped so as to form a space filled with a sufficient amount of the encapping agent between the first insulator and the first insulator.

The first insulator is integrated with the semiconductor pellet via an encapsulant, and strengthens the mechanical strength of the semiconductor pellet such as preventing chipping of the end of the pellet and increases the creepage distance from the top surface to the bottom surface of the semiconductor pellet. It has the functions of preventing creeping discharge and positioning the pressure contact electrodes (called posts).

The first insulator in the present invention satisfies this function. Particularly, even if the encapsulating agent leaks from the contacting portion, the gap provided between the first insulator terminal end portion inward of the portion contacting the pellet principal surface and the pellet main surface is the leakage end. According to the method for filling the encapsulating agent of the present invention described later, the amount of the capping agent is small, and the capping agent does not flow out from the end of the first insulator because it is stored in the void. Accordingly, it is not necessary to adjust the amount of the encapsulation agent in consideration of the outflow thereof, and it is possible to fill a sufficient amount.

The encapsulating agent is applied to the bevel surface of the pellet where the PN junction is exposed and in the vicinity thereof to protect the pellet surface from contamination and damage, prevent creeping discharge, and firmly bond and integrate the semiconductor pellet and the first insulator. Have. The sufficient amount of the encapping agent means an amount necessary to satisfy this function. The encapsulating agent in the present invention is
The space between the pellet main surface and the first insulator, including the area between the outer peripheral edge of the pellet main surface and the portion inside the outer peripheral edge that contacts the first insulator, is filled. To be done. In this way, the area of adhesion between the semiconductor pellet main surface and the first insulator increases, and there is no peeling between the pellet and the first insulator.

According to the method for manufacturing a semiconductor device of the present invention, after the semiconductor pellets are incorporated into the first insulator and positioned relative to each other, a pressure is applied between the first insulator and the pellets to bring the contacting parts into contact with each other. By the method of filling the capping agent, the adhesion between the first insulator and the pellets is always maintained during the filling process, and the outflow of the encapsulating agent is prevented.

(Embodiment) FIG. 1 is a sectional view showing one embodiment of a semiconductor device of the present invention. The semiconductor device 10 includes a silicon pellet 2 having a PN junction and a first insulator 11 as an encapsulating agent 13
It is fixed and integrated via. In this embodiment, the silicon pellet 2 is a GTO (Gate Turn Of) having a diameter of 33 mm.
f Thyristor), the bevel surface 2a has two PN junctions 2
b and 2c are exposed. The first insulator 11 is made of a ring-shaped silicone rubber, and its plan view, sectional view and partially enlarged sectional view are shown in FIGS. 2 (a), (b) and (c), respectively. The first insulator is
The main surface 2d is in contact with the main surface 2d along an inner ring 11c which is inward from the outer peripheral edge of one main surface 2d (downward in the drawing) of the pellet, and the inner surface of the first insulator is further inside the contacting portion 11c. An air gap 11a is provided between it and 2d. Outside the contacting portion 11c, the first insulator 11 and the pellet main surface 2
is space 11b is formed between the d, projecting section 11d of the pellet 2 side walls of the first insulator second insulator together with the space 11b so as to face the (bevel surface) 2a surrounds the pellet 2 (encapsulants) A space for filling 13 is formed.

The method of filling the encapsulating agent will be described with reference to FIG. The silicon pellets 2 are placed on the first insulator 11 and positioned relative to each other. Next, as shown in FIG. 3, a weight 16 is placed on the silicon pellet 2 and the first insulator 11 is placed.
And pellet 2 are pressed together. The pressure contact force required at this time varies depending on the diameter of the pellet and the contact area between the pellet and the first insulator, but in this example, a weight of about 100 g was used and good results were obtained. Next, the encapsulating agent is filled while applying a pressing force. Finally, the encapsulating agent is heat-cured to obtain a semiconductor device. In this semiconductor device 10 , the encapsulating agent does not flow out to the pressure contact region between the semiconductor pellet main surface and the electrode post, and the semiconductor pellet and the first insulator are firmly fixed by the encapsulating agent.

Other embodiments of the present invention are shown in FIGS. 4, 7 and 8 and reference examples are shown in FIGS. However, in the reference example, the shape of the first insulator other than the portion below the main surface of the semiconductor pellet and outside the portion in contact with the main surface of the pellet is referred to as the shape of the first insulator of the present invention. (The same applies to the following reference examples.) The same reference numerals as in FIG. 1 indicate the same or corresponding parts. The semiconductor (silicon) pellets 2 mainly include diodes, transistors, various thyristors and the like used for electric power, and have different bevel structures. All the first insulators 11 have voids 11a and the encapsulating agent 13 is filled by the manufacturing method of the present invention. It is desirable to provide a space 11b between the semiconductor pellet main surface and the first insulator, but as shown in FIGS. 5 and 6, the space 11b is provided.
Even if the encapsulation agent is not provided, the outflow of the encapsulation agent is eliminated according to the present invention, so that it is possible to fill a sufficient amount to satisfy the function of the encapsulation agent.

FIG. 9 shows another embodiment of the semiconductor device of the present invention, FIGS. 10 and 11 show a reference example of the semiconductor device of the present invention, and FIG.
The figure shows another filling method of the encapsulating agent in the present invention. The semiconductor device shown in FIGS. 9 and 11 has the auxiliary insulator 1 of silicone rubber in addition to the first insulator 11 of the present invention.
4a and 14b are added to the top side of the pellet,
This aims at securing a creepage distance, reinforcing the mechanical strength of the pellet, and positioning the electrode post.

The auxiliary insulator is provided with a gap 11a for preventing the outflow of the encapsulating agent. In FIG. 9, after filling the encapsulation agent 13a between the pellet 2 and the first insulator 11 by the manufacturing method of the present invention, the bevel groove on the top surface of the pellet is filled with the second encapsulation agent 13b. Auxiliary insulator 14a is attached to. In FIG. 11 , the semiconductor pellet 2 is placed on the first insulator 11 of the present invention, and the auxiliary insulator 14b is placed on the top surface side of the pellet. After alignment, the weights 17 and 18 are placed as shown in FIG. And the encapsulating agent is filled while the pellet 2 and both insulators are pressed against each other.

FIG. 10 shows that the encapsulant is filled between the pellet 2 and the first insulator 11 by the manufacturing method of the present invention, and then the auxiliary insulator 15 for positioning the electrode post is attached.

As a result of verifying the above various examples, good results were obtained. For example, according to the conventional first insulator and encapsulating agent filling method shown in FIG.
Although 50 GTOs of 33 mmφ were prepared, outflow of the encapping agent was observed in all GTOs. On the other hand, a similar GTO was prepared by the first insulator of the present invention shown in FIG. 1 and the encapsulating agent filling method, but no outflow of the encapping agent was observed in all GTOs. This eliminates the need for a step of scraping off the encapsulation agent that has flowed out, and keeps the manufacturing process clean without the generation of encapsulation. This also contributes to improving the manufacturing yield. Moreover, since the encapsulating agent is not sandwiched between the pellet main surface and the pressure contact electrode (post), good contact is obtained, and a sufficiently long creepage distance can be obtained.
As a result, a semiconductor chip having stable characteristics can be formed and the manufacturing yield can be improved.

[Effects of the Invention] According to the semiconductor device and the method for manufacturing the same of the present invention, at the time of filling the encapsulating agent, the encapsulating agent does not flow out into the pressure contact region between the main surface of the semiconductor pellet and the electrode post. A sufficient amount of the encapsulating agent is provided between the pellet and the first insulator so that the peripheral edge does not separate from the encapsulating agent or the first insulator and the functions of the first insulator and the encapsulating agent are satisfied. Can be filled in the meantime.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device of the present invention, FIG. 2 (a),
(B) and (c) are respectively a plan view, a cross-sectional view and a partially enlarged cross-sectional view of the first insulator according to the present invention, and FIG. 3 is a view for explaining the method for manufacturing the semiconductor device of FIG. 1, and FIG. 5 is a partially enlarged cross-sectional view showing another embodiment of the semiconductor device of the present invention,
6 and 6 are partially enlarged sectional views showing a reference example of a semiconductor device of the present invention, and FIGS. 7 to 9 are partially enlarged sectional views showing another embodiment of the semiconductor device of the present invention, respectively. 10 and 11 are partially enlarged cross-sectional views showing another reference example of the semiconductor device of the present invention, FIG. 12 is a view for explaining another filling method in the present invention, and FIG. 13 is a conventional semiconductor device. FIG. 14 is a cross-sectional view for explaining the conventional problems. 1, 11 ... First insulator, 11a ... Air gap, 11b ...
Space, 11c ・ ・ ・ Part that contacts the main surface of the pellet, 11d ・ ・ ・
… Projection part, 2, 2 …… Semiconductor pellet, 2a …… Pellet side wall, 2b b, 2c …… PN junction, 2d …… Pellet main surface, 3, 13 …… Second insulator (encapping agent), 5 ...
... Pressure contact electrodes, 14a, 14b ... Auxiliary insulators, 16, 1
7, 18 ... Weight.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-60-207340 (JP, A) Actual opening 57-69240 (JP, U) Actual opening 57-91246 (JP, U)

Claims (2)

[Claims] 1. A semiconductor pellet having a PN junction and a ring-shaped insulator which is in contact with the pellet main surface along the inside of the outer peripheral edge of the pellet main surface and faces the pellet side wall to surround the pellet. A first insulator having a portion, and a second insulator filled between the pellet and the first insulator, the first insulator terminal portion further inside than a portion in contact with the pellet main surface. A space between the pellet and the main surface of the pellet, and a space between the pellet and the first insulator that is filled with a sufficient amount of the second insulating material. A semiconductor device comprising a space formed between the first insulator and the pellet main surface up to a portion in contact with the first insulator on the inner side of the outer peripheral edge. 2. A semiconductor pellet having a PN junction and a ring-shaped insulator which is in contact with the main pellet surface along the inside of the outer peripheral edge of the main pellet surface and faces the side wall of the pellet to surround it. A first insulator having a portion and a second insulator filled between the pellet and the first insulator, the first insulator terminal portion being further inside than a portion in contact with the pellet main surface. A space between the pellet and the main surface of the pellet, and a space between the pellet and the first insulator that is filled with a sufficient amount of the second insulating material. In a method for manufacturing a semiconductor device including a space formed between a first insulator and a pellet main surface up to a portion in contact with a first insulator on an inner side of an outer peripheral edge, the pellet is incorporated into the first insulator, After positioning the The while applying pressure between the Tsu bets 2
A method of manufacturing a semiconductor device, comprising the step of filling an insulator.