JPH0483370A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent positional accuracy of a lead from decreasing by allowing a protrusion to protrude from a glass sealing part of at least one of a base and a cap toward the other opposed surface, and supporting a lead group in contact with the protrusion. CONSTITUTION:A group of inner parts 9a is bridged between both protrusions 16a and 16b to be mechanically secured in a unit lead frame 2 on a low melting point glass layer 15. Since the protrusions 16a, 16b have a mechanical strength, a group of leads 9 by the protrusions 16a, 16b is effectively supported from below. In this case, if a superposed part 20 is placed on a multistage lead frame 1 to apply a suitable load thereto, the group of the leads 8 is forcibly sunk when the glass 15 is melted. Thus, the group of the leads 9 is effectively brought into contact with the protrusions 16a, 16b. Therefore, the positional accuracy of the group 9 to a base 11 accurately coincides with a predetermined size by the protrusions 16a, 16b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technology for manufacturing semiconductor devices, particularly a technology for forming a hermetically sealed package using low-melting glass.
The present invention relates to a technique that is effective for use in manufacturing semiconductor integrated circuit devices (hereinafter referred to as ICs) that are equipped with a hermetically sealed package sealed with low melting point glass.

[Conventional technology]

As a method for manufacturing an IC having a hermetically sealed package, a low melting point glass is applied to a base or cap made of ceramic by screen printing, and
By pre-baking this at around the softening temperature of glass (approximately 400°C), a low melting point glass layer is formed in advance, and a semiconductor pellet (hereinafter referred to as "bellet") is formed on the base.
After assembling the lead frame, etc., the base and cap are combined, and the low melting point glass layer is heated to a high temperature (440°C or higher) with the lead frame sandwiched between the mating surfaces. There is a method in which a sealing portion is formed by melting and solidifying, and the bonding surfaces of the base and the cap are sealed by the sealing portion.

An example of a method for hermetically sealing a lead wire using low melting point glass is JP-A-53-90867.

In addition, as an example that describes an IC equipped with a hermetically sealed package, see "Electronic Materials 19" published by Kogyo Chosenkai Co., Ltd.
“November 1987 special issue” published November 1987 PL38
~P145, there is.

[Problem to be solved by the invention]

In manufacturing methods for semiconductor devices equipped with hermetically sealed packages using such low-melting-point glass, since low-melting-point glass is used as the sealing material, lead frame attachment is difficult due to the process or bullet bonding. As the low-melting glass melts or softens during each process, such as the manufacturing process and package molding process, the leads sink or become misaligned.As a result, the positions of the leads in the height and pitch directions change. The inventor of the present invention has revealed that there is a problem in that the accuracy decreases.

A first object of the present invention is to provide a semiconductor device manufacturing technique that can prevent a decrease in lead position accuracy.

By the way, even after the low-melting glass, which forms the glass seal, is melted and the inside of the cavity is cut off from the outside atmosphere, the entire package is still heated, so the gas remaining inside the cavity is heated. As a result of the expansion, gas escapes to the outside by displacing a portion of the molten glass, resulting in the formation of a so-called blowhole.

A second object of the present invention is to provide a semiconductor device manufacturing technique that can prevent the occurrence of blowholes.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, a semiconductor pellet in which an electronic circuit is built, a plurality of leads that are electrically connected to this semiconductor pellet and take out the electronic circuit to the outside, and an inner group of the semiconductor pellet and the leads are hermetically sealed. The package includes a base on which the semiconductor pellet is assembled, a cap placed on the base so as to cover the semiconductor pellet, and a base and cap made of low melting point glass. In a semiconductor device, the semiconductor device includes a glass sealing portion formed between mating surfaces, sealing the base and the cap, and having the lead group passed through the glass sealing portion. A convex portion is provided on the glass sealing portion to protrude toward the other opposing surface, and the lead group is abutted and supported by the convex portion.

The method for manufacturing the semiconductor device further includes: providing a protruding portion in a region corresponding to the glass sealing portion of at least one of the base and the cap; A process in which low-melting point glass is applied to corresponding areas, and the base and cap are arranged and put together so as to sandwich the lead group, and are heated to a temperature higher than the low-melting point glass to form a glass sealing part. and the step of abutting the lead group against the convex portion.

[Effect]

According to the above-mentioned means, in the step of forming the glass sealing part, since the protruding part is provided on at least one of the base and the cap, the lead group is supported on the protruding part when the low melting point glass is melted. state. Therefore, the position of the lead group is regulated by the convex portion, so that proper positional accuracy with respect to the hermetically sealed package is maintained.

On the other hand, since the glass sealing portion is properly formed by melting and solidifying the low melting point glass, a hermetically sealed package with good quality and reliability is manufactured.

In addition, if the thickness of the glass sealing part is partially narrowed by protruding protrusions inside the glass sealing part, penetration of the blowhole can be directly prevented. At the same time, since the surface tension of the low melting point glass is increased, deep penetration of the blowhole into the sealed portion is prevented.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view showing an IC equipped with a hermetically sealed package which is an embodiment of the present invention, and FIG. 2 and subsequent figures are explanatory diagrams showing a method for manufacturing the IC which is an embodiment of the present invention. It is.

In this embodiment, the semiconductor device 1 according to the present invention is a flat package op glass IC (hereinafter referred to as FP
It is structured as G.IC (G.IC).

Hermetically sealed package 25 in this FPG/IC 26
A base 11 in which semiconductor pellets (hereinafter referred to as pellets) 22 are bonded by a bonding layer 21 made of a gold-silicon eutectic layer, and a cap 17 attached to the base are bonded together with a low melting point glass between the mating surfaces. It is configured by being sealed by a sealing part 24 consisting of. A group of nine leads is inserted into the hermetically sealed package 25 so as to pass through the glass sealing portion 24 between the mating surfaces of the base and the cap, and this group of leads is connected to a multiple lead frame as described later. is formed using. Inside the package 25, wires 23 are bridged by bonding both ends between each lead and each electrode of the pellet, and outside the package 25, the leads are arranged in a straight line shape with the same length. Molded.

A square frame-shaped convex portion 16 is provided on the mating surface of the base 11 in the glass sealing portion 24 to protrude toward the cap 17 side, and the nine groups of leads are abutted on this convex portion 16. It is supported from below. The FPG/IC 26 configured as described above is manufactured by the following manufacturing method.

Hereinafter, a method for manufacturing this FPG/IC, which is an embodiment of the present invention, will be explained. This explanation clarifies the details of the configuration of the FPG/IC.

In this example, the FPG-IC manufacturing method includes a second
A multi-lead frame 1 shown in the figure is used. This multiple lead frame 1 is made of a thin plate made of iron-based (iron or its alloy) material such as 4270I, and is integrally formed by a suitable method such as punching press processing or etching processing. In this multi-lead frame l, a plurality of unit lead frames 2 are arranged side by side in one row in the lateral direction. However, in the drawing, only one unit is illustrated (the same applies hereinafter).

The unit lead frame 2 includes a pair of outer frames 3 each having a positioning hole 3a, and both outer frames 3 extend in parallel at a predetermined interval. Between the adjacent unit lead frames 2.2, a pair of section frames 4 are connected to both outer frames 3.3.
The unit lead frames 2 are arranged in parallel to each other and perpendicular to the outer frame and integrally constructed between them, and a unit lead frame 2 is constructed within a substantially square frame body formed by these outer frames and section frames.

In each unit lead frame 2, tie bar support portions 5 formed in a substantially square shape are integrally protruded from each connection portion of the outer frame 3 and section frame 4 and are arranged radially inward. Each tie bar support portion 5 has an inner corner cut out at approximately 45 degrees. Each tie bar support part 5
A slit 6 is disposed along the slope of the notch, and a tie bar hanging member 7 is formed in an arch shape inside the slit 6. There are four tie bars 8 inside each tie bar hanging member 7.
are arranged in a substantially square frame shape concentric with the frame formed by the outer frame 3 and the Cefsilon frame 4, and these tie bars 8 are approximately connected to the tie bar hanging members 7 at both ends thereof. It is suspended from these by being connected at a 45 degree angle. Adjacent tie bars 8.8 intersect at an angle of approximately 90 degrees.

A plurality of ties 9 are disposed on these tie bars 8 at equal intervals in the longitudinal direction, and project integrally so as to be parallel to each other and orthogonal to the tie bars 8. The inner ends of each lead 9 are arranged so that the tips are aligned in a square shape, thereby forming an inner part 9a,
An aluminum coating (not shown) is deposited on the surface of the tip end of the inner part 9a by a suitable means such as vapor deposition to improve the bondability of wire bonding, which will be described later. On the other hand, the outer end portions constituting the outer portions 9b of each lead 9 are connected to the outer frame 3 and the section frame 4.
They are separated and separated.

In this embodiment, the manufacturing method for the FPG・■c includes the base 11 shown in FIGS. 3 and 4.
The base 11 is configured to form a hermetically sealed package in cooperation with a cap to be described later. The base 11 includes a main body 12, which is made of ceramic whose main component is alumina (A 1 *Ox) and is formed into a substantially square planar shape. A cavity recess 13a is arranged concentrically on one plane (hereinafter sometimes referred to as a mating surface or upper surface) that is a mating surface with the cap of the main body 12, and has a square rich shape in plan view. Moreover, it is integrally formed to have a constant depth. A pounding bed 1-4 is placed in the center of the bottom of the cavity recess 13a and is adhered so as to have a shape slightly larger than that of the pellet, and this pounding bed 14 is made of gold (Au).
etc., and metallization is performed by an appropriate means such as a vapor deposition method.

Cavity recess 13a in the upper surface of the base body 12
A pair of protrusions 16a and 16b are integrally protruded outward from each other.The protrusions 16a and 16b are each formed in the shape of a square frame with large and small diameters, and are spaced at appropriate intervals from each other. and are respectively disposed concentrically in the cavity recess 13a. The cross-sections of both convex portions 16a and 16b are formed into a substantially equilateral triangular shape, and the convex portions 16a and 16b are disposed at the same height so that their negative sides touch the upper surface of the base body 12. It is set up.

Cavity recess 1 in base body 120 mating surface
3a, the low melting point glass layer 15 has convex portions 16a, 1
The thickness is more than the height of 6b, 250~300u
The low melting point glass layer 15 is formed into a square frame shape so as to completely surround the cavity recess 13a.

The low melting point glass layer 15 is made of amorphous glass having a melting point of about 400'C, a working temperature of about 435C, and the following composition. That is, in terms of weight ratio, PbO is about 51%, SnO is about 22%,
The base body 1 is made of an amorphous glass containing about 5% Sin and about 12% ZnO.
It is coated on the base body 12 by being coated on the mating surfaces of the base body 12 by a suitable means such as screen printing, and then heated and baked at 440° C. or higher in a heating furnace. In this way, the low melting point glass layer I5 is preliminarily fired at a temperature of 440° C. or higher, so that it is completely and strongly bonded to the ceramic surface of the base body 12.

On the other hand, as shown in FIGS. 5 and 6, the cap 17, which cooperates with the base 11 to form a hermetically sealed package, has a main body 18.
is formed into a square flat plate shape between the base body 12 and the groove. A cavity recess 13b is arranged concentrically on the surface of the cap body 18 that is mated with the base 11 (hereinafter sometimes referred to as the lower surface), and is larger than the cavity recess 13a on the base side. The depressions have similar shapes and are integrally formed to a constant depth.

On the outside of the cavity recess 13b on the mating surface of the cap body 18, a low melting point glass layer 19 is made of the same material as the low melting point glass layer 15 on the base side, and is coated by being fired in advance. It is worn. That is, the cap side low melting point glass layer 19 is formed by applying a paste made of the same amorphous glass material as the base side low melting point glass layer 15 onto the mating surface of the cap body 18 by a suitable process such as screen printing. After being coated by means of means, it is heated to 440'C or higher and baked in a heating furnace, so that it is coated on the cap body 18 in advance.

The base 11 configured as described above is assembled to the multiple lead frame 1 having the above configuration for each unit lead frame 2 as shown in FIGS. 7 and 8, respectively. That is, each base 11 is oriented so that its low melting point glass layer 15 is in contact with the flat surface (hereinafter sometimes referred to as the lower surface) of the unit lead frame 2 on which the aluminum coating is not applied, and the cavity The opening edge of the tee recess 13a is a reed inner part 9a.
are arranged and set so as to match the tip group of.

While the set state of the base 11 group is maintained, the multi-lead frame 1 is heated to a temperature of approximately 4°C, which is the working temperature of low-melting glass.
By passing through a heating furnace at a temperature of 35° C., the low melting point glass layer 15 is melted and then solidified. Accordingly, the inner portions 9a of the unit lead frame 2 are bridged between the convex portions 16a and 16b on the low melting point glass layer 15, and are mechanically fixed. This double convex portion 16
When the nine groups of leads are fixed by a and 16b, the convex portion 16a
, 16b have mechanical strength, so that they are reliably supported from below.

At this time, as shown in FIG. 8, by placing the stack 20 on the multi-lead frame 1, when an appropriate load is applied, when the low melting point glass layer 15 melts, the lead Since the 9th group is forcibly sunk, the 9th lead group is reliably brought into contact with the convex portions 16a and 16b. When the lead group 9 is reliably brought into contact with the protrusions 16a, 16b, the positional accuracy of the lead group 9 with respect to the base 11 will accurately match the dimensions predefined by the protrusions 16a, 16b.

In this way, for each unit lead frame 2, 1 base
A pellet bonding operation and a wire bonding operation are performed for each unit lead frame 2 on the multiple lead frame 1 in which the lead frame 1 is assembled. This bonding work is sequentially performed for each unit lead frame 2 by pitch-feeding the multiple lead frames 1 in the lateral direction.

Through this bonding process, as shown in FIGS. 9 and 10, the pellet 22, which serves as a semiconductor integrated circuit element into which an electronic circuit such as a bipolar integrated circuit has been built in the previous process, is bonded to each unit lead. It is brought into contact with the bonding floor 14 of the base 11 in the frame 2 via gold foil, and is fixed by a gold-silicon eutectic bonding layer 21 formed by rubbing at a working temperature of 420° C. to 430 ”C. At this time, the lead 9 groups in the unit lead frame 2 are connected to the convex portion 1.
6a and 16b, it will not sink even if the low melting point glass layer 15 melts. That will happen.

Then, the pellet 22 bonded to the base 11
An ultrasonic wire bonding apparatus (0) in which a wire 23 made of an aluminum-based material is connected between the electrode pad of the unit lead frame 2 and the inner part 9a of the lead 9 in each unit lead frame 2, and a wedge is used as a bonding tool.
By using a so-called US bonder, both ends are bonded and bridged. At this time as well, the initial accuracy of the nine groups of leads is maintained. As a result, the integrated circuit built into the pellet 22 is electrically exposed to the outside via the electrode pads, the wires 23, and the inner and outer portions 9a and 9b of the leads 9.

In this way, the multiple J-type frame 1 is assembled with each unit lead frame 2 and the block base 11, and the pellet bonding work and the wire bonding work are sequentially performed, as shown in FIGS. 11 and 12. A sealing operation is performed to form the hermetic sealing cage 25 shown in FIG.

That is, as shown in FIG. 11 and FIG. In addition, the base 1
It is covered and set to match 1. This center
The multi-lead frame 1 is heated in a heating furnace at approximately 435°C, which is the working temperature of the low-melting glass layers 15 and 19, while maintaining the same state and applying an appropriate joining force between the base 11 and the cap 17. When passed through, the low melting point glass layers 15, 19 of the base 11 and cap 17 are melted, thereby forming a sealing portion 24 made of the low melting point glass layer. As a result, the mating surfaces of the base 11 and the cap 17 are sealed together by the glass sealing portion 24, forming a package 25 that hermetically seals the inside of the cavity 13.

At this time, the heating temperature for forming the glass sealing portion 24 is set to a temperature at which the low melting point glass layers 15 and 19 soften, that is, 435° C. or lower. therefore,
The adverse effects of thermal stress on internal components such as the pellet 22 and wire 23 that have already been assembled to the base 11 of the hermetically sealed package 25 are suppressed.

In addition, since the convex portions 16a and 16b do not soften,
The group of leads 9 is supported by the convex portions 16a and 16b while maintaining the initial positional accuracy.

On the other hand, in the low melting point glass layers 15 and 19,
By reaching the softening temperature, a reliable glass sealing portion 24 can be stably formed. At this time, if the thickness of the glass sealing part 24 is partially reduced by protruding the convex parts 16a and 16b inside the glass sealing part 24, the penetration of the blowhole is prevented. Since this is directly prevented and the surface tension of the molten low-melting glass is increased, deep penetration of the blowhole into the glass sealing portion 24 is prevented.

By the way, between the low melting point glass layer and the ceramic surface, the adhesion between the low melting point glass layer and the ceramic surface becomes uncertain or unstable at the softening temperature of the glass. As a result, the hermetic sealing performance deteriorates, and the quality and reliability of the product deteriorate.

However, in this embodiment, as mentioned above, the base 1
1, before the pellets 22 are loaded on the low melting point glass layer 1.
5 and 19 are completely adhered to the surfaces of the base body 12 and the cap body 1B, respectively, by being heated to 440″C or more, so even if the heating temperature in this sealing step is about the softening temperature, The adhesive state between the surfaces of the base body 12 and the cap body 18 and the glass sealing portion 24 is safe, strong, and stable.

The multiple lead frame 1 has the glass sealing portion 24 formed as described above and the hermetically sealed package 25 formed therein.
In the solder plating process, a solder plating film is entirely applied (1 not shown).

After that, the multi-lead frame 1 was coated with a plating film.
In the lead cutting and forming step, the tie bars 8 are sequentially cut off for each unit lead frame, and the outer portion 9b of each lead 9 is formed into a linear shape of a predetermined length (not shown). In this way, the FPG/IC 26 shown in FIG. 1 was manufactured.

According to the embodiment described above, the following effects can be obtained.

(1) By providing a protruding portion in the area corresponding to the glass sealing portion on the upper surface of the base, the lead group is placed on the protrusion while the low melting point glass is in a molten state during the glass sealing portion forming process. Since it is in a supported state, the lead group can maintain the positional accuracy specified by the convex part, and on the other hand, the glass sealing part can be properly formed by melting and solidifying the low melting point glass. I can do it.

(2) By maintaining the positional accuracy of the lead group in the process of forming a hermetically sealed package with a glass sealing part, the position of the lead group in the height direction and pitch direction with respect to the hermetically sealed package is Since the precision can be improved, the quality and reliability of the hermetically sealed package using the glass sealing part can be improved.

(3) Before the pellet is assembled to the base, the low melting point glass layer formed on the base and cap is heated above the melting point to completely and completely bond the low melting point glass layer to the base and cap surfaces. Since it is possible to maintain stable adhesion, by setting the heating temperature during the sealing process low, it is possible to suppress thermal stress on the pellet assembled to the base while ensuring the desired sealing performance. This makes it possible to improve the quality and reliability of the hermetically sealed package using the glass sealing part.

(4) By providing a protrusion inside the glass sealing part, it is possible to prevent the blowhole from penetrating deeply, so the sealing allowance for the hermetically sealed package can be extremely small, allowing high-density mounting. It is possible to provide a compact package with improved sealing reliability.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, since the protrusions only need to mechanically support the group of leads 9, as shown in FIG.
c, 16d may be provided protrudingly.

Further, as shown in FIG. 14, convex portions 16e, 16f, and 16
g and 16h may be provided in a protruding manner. According to this embodiment, the height positional accuracy of the group of leads 9 can be ensured both in the vertical direction.

Furthermore, the material for forming the base and cap is not limited to alumina ceramic, but may also be mullite, aluminum nitride, silicon carbide ceramic, epoxy resin, or the like.

In the above explanation, the invention made by the present inventor was mainly applied to FPG-IC, which is the background field of application, and its manufacturing method, but it is not limited thereto. The present invention can be applied to general semiconductor devices such as other ICs that are equipped with a hermetically sealed pancage using a sealing part.

[Effects of the Invention] The effects obtained by typical inventions disclosed in this application are briefly explained as follows.

By providing a protrusion in a region corresponding to the glass sealing part on the mating surface of at least one of the base and the cap, the lead group can be removed while the low melting point glass is in a molten state in the glass sealing part forming process. Since it is supported on the convex part, the lead group can maintain the positional accuracy specified by the convex part, and on the other hand, the glass sealing part can be properly maintained by melting and solidifying the low melting point glass. It can be formed into

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an FPG-IC which is an embodiment of the present invention, and FIGS. Figure 2 is a partially omitted plan view showing the multi-lead frame used therein, Figures 3 and 4 are a plan view and front sectional view showing the base, and Figures 5 and 6 are the caps. A bottom view and a front sectional view, FIGS. 7 and 8 are a partially omitted plan view and a front sectional view showing the base and lead frame after they are assembled, and FIGS. 9 and 10 are the views after the bellet and wire bonding. FIGS. 11 and 12 are a partially omitted plan view and a front sectional view showing a multi-lead frame after molding a hermetically sealed package. FIG. 13 is a partially cutaway plan view showing a second embodiment of the present invention. FIG. 14 is a partially cutaway front view showing Embodiment 3 of the present invention. 1...Multiple lead frame, 2...Unit lead frame, 3...Outer frame, 4...Section frame, 5...
Tie bar support part, 6... Slit, 7... Tie bar hanging member, 8... Tie bar, 9... Lead, 9a.
...Inner part, 9b...Outer part, 1! ...Base, 12...Base wood 13a, 13b...Cavity recess, 13...Cavity 14...Bonding floor, 15...Low melting point glass layer, 16a to 16h
... Convex portion, 17... Cap, 18... Cap body, 19... Low melting point glass layer, 20... Overlapping,
21... Bonding layer, 22... Pellet, 23
... wire, 24 ... glass sealing part, 25 ... hermetically sealed package, 26 ... FPG/IC (semiconductor device).

Claims (1)

[Scope of Claims] 1. A semiconductor pellet in which an electronic circuit is built, a plurality of leads that are electrically connected to the semiconductor pellet and take out the electronic circuit to the outside, and inner parts of the semiconductor pellet and the leads. The package includes a base on which the semiconductor pellets are assembled, a cap placed on the base to cover the semiconductor pellets, and a package made of low melting point glass. a glass sealing portion formed between the mating surfaces of the base and the cap to seal the base and the cap, and through which the lead group is penetrated; A semiconductor device, wherein a convex portion is provided on the glass sealing portion of at least one of the glass sealing portions and protrudes toward the other opposing surface, and the lead group is abutted and supported by the convex portion. 2. The semiconductor device according to claim 1, wherein the convex portion is formed in a continuous ring shape. 3. A method for manufacturing a semiconductor device according to claim 1, comprising: providing a protruding portion in a region corresponding to the glass sealing portion on at least one of the base and the cap; A step in which low melting point glass is applied to areas corresponding to the glass sealing portions on both sides, and the base and cap are arranged and put together so as to sandwich the lead group, and heated to a temperature higher than the low melting point glass. A method for manufacturing a semiconductor, comprising: forming a glass sealing portion and bringing the group of leads into contact with the convex portion.