JPH0483364A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the position accuracy of leads from decreasing by forming sealing sections made of two sorts of sealing glass having different melting points. CONSTITUTION:The joined face of a base 11 and that of a cap 16 are sealed with glass sealing parts 24 to form a package 25 having a hermetically sealed cavity 13. The heating temperature to form the glass sealing parts 24 is set to 435 deg.C or lower to soften amorphous glass layers 15A and 19. Therefore, the bad effects of thermal stress applied to inner components, such as a pellet 22 and wires 23, built in the base 11 of the hermetically sealed package 25 are suppressed. Because the heating temperature is lower than 460 deg.C, which is the melting point of a crystal glass layer 16A, the layer 16A is not softened and a lead group 9 is indicated with the initial position accuracy thereof maintained by the crystal glass layer 16A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technology for manufacturing semiconductor devices, and in particular to a technology for forming a hermetically sealed pancage 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 manufacturing method for an IC with a hermetically sealed package, a low melting point glass is applied by screen printing to a base or cap made of ceramic, and this is heated at around the softening temperature of glass (approximately 400 degrees Celsius). A low melting point glass layer is previously formed by calcination, and semiconductor pellets (hereinafter referred to as pellets) are formed on the base.

), lead frame, etc. are assembled, the base and the cap are combined, and the lead frame is sandwiched between the mating surfaces, and heat treatment is performed at a high temperature (440°C or higher) to form the low melting point glass. There is a method in which the layers are melted and solidified to form a sealing portion, 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 Edition” Published November 1987 P138
~P145, there is.

[Problem to be solved by the invention]

In the manufacturing method of semiconductor devices equipped with hermetically sealed packages using such low-melting point glass, since low-melting point glass is used as the sealing glass, lead frame attachment is carried out during the process or pellet bonding process. As the low-melting glass melts or softens during each process, such as the package molding process, the leads sink or become misaligned, resulting in positional accuracy in the height and pitch directions of the leads. The inventor of the present invention has revealed that there is a problem in that the

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device manufacturing technique that can prevent a decrease in lead position accuracy.

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 for Solving the Problems] Representative inventions disclosed in this application will be summarized 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 sealing glass that is used to connect the base and the cap. A semiconductor device comprising a sealing portion formed between mating surfaces, sealing the base and the cap, and having the lead group passed through, the sealing portion having two types having different melting points. It is characterized by being made of sealing glass.

The manufacturing method for the semiconductor device also includes: applying two types of sealing glass having different melting points to regions corresponding to the sealing portion of at least one of the base and the cap, and applying both glasses. The lead group is attached to the glass layer portion which is heated to a temperature higher than the melting point of the low melting point glass on the high temperature side, and the coated layer portion of the low melting point glass on the high temperature side is melted and solidified. and a step in which the base and the cap are arranged and brought together so as to sandwich the lead group, and are heated at a temperature higher than the low-temperature side low-melting point glass to form a sealed part. Features [Function] According to the above-described means, in the glass sealing portion forming step, the high temperature side low melting point glass layer portion to which the lead group is attached is not melted, so that the low temperature side low melting point glass is in a molten state. In this case, the lead group is supported on the high temperature side low melting point glass layer.

Therefore, the lead group maintains positional accuracy in the initial state where it is attached to the high temperature side low melting point glass.

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

〔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. It is a diagram.

In this example, the semiconductor device according to the present invention is a flat package of glass IC (hereinafter referred to as F
It is configured as PG・rc.

Hermetically sealed package 25 in this FPG-1c26
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 leads 9 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, the cap, and the plate 7. It is formed using a continuous lead frame.

Inside the pan cage 25, a wire 23 is bridged between each lead and each electrode of the pellet by bonding both ends thereof, and outside the package 25, the leads are arranged in a straight line shape with the same length. It is molded into.

The glass sealing portion 24 is composed of two types of sealing glass having different melting points. The FPC-IC 26 configured as described above is manufactured by the following manufacturing method.

A method of manufacturing this FPG-IC, which is an embodiment of the present invention, will be described below. With this explanation, the FP(1,-I
Configuration details for C are revealed.

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, only one unit is illustrated in the drawing (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
Slits 6 are arranged along the slopes of the notches and are bored therein, respectively, and a tie bar hanging member 7 is formed in an arch shape inside the slits 6. There are four tie bars 8 inside each tie bar hanging member 7.
are arranged in a substantially square frame shape that is concentric with the frame formed by the outer frame 3 and the section frame 4, and these tie bars 8 are substantially 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 leads 9 are disposed on these tie bars 8 at regular intervals in the longitudinal direction, and are integrally protruded from each other 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.
separated and separated from.

In this embodiment, the manufacturing method for the FPG-IC 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 1-1 includes a main body 12, and the main body 12 is made of ceramic whose main component is alumina (Altos), and is formed into a substantially square planar shape. One plane that is the mating surface of the main body 12 with the cap (hereinafter sometimes referred to as the mating surface or the top surface).

) A cavity recess 13a is arranged concentrically on the top,
It is integrally formed to have a square depression shape in plan view and a constant depth. Cavity recess 13
A ponding floor 14 is arranged in the center on the bottom surface of a.
The bonding bed 14 is deposited so as to have a shape slightly larger than that of the pellet, and the pounding bed 14 is made of gold (Au) or the like and is metalized by a suitable means such as vapor deposition.

Cavity 13a on the mating surface of base body 12
On the outside of
The glass coated layers 15 and 16 are uniformly coated to a thickness of approximately μm, and are formed into a square frame shape so as to completely surround the cavity recess 13a. Low temperature side low melting point glass coating layer 1
No. 5 is constructed using an amorphous glass having a melting point of about 400°C and a working temperature of about 435°C. The high temperature side low melting point glass coating layer 16 is made of crystalline glass having a melting point of about 460°C and a working temperature of about 500°C, and has particularly low thermal expansion and high mechanical properties. things are used. High temperature side low melting point glass coating layer (hereinafter sometimes referred to as crystal glass coating layer) 1
6 is disposed approximately at the center in the radial direction on the outside of the cavity recess 13a, and is formed into a square frame shape with a constant width. In addition, the low temperature side low melting point glass coating layer 15 (hereinafter referred to as
It is sometimes called an amorphous glass coating layer. ) are arranged on both sides of this crystal glass coating layer 16, and are each formed in the shape of a square frame with a constant width. These coating layers 15 and 16 are made of a paste that is made of a specific amorphous glass material and a crystalline glass material, respectively, on the base body 12.
The base body I2 is coated by coating the mating surfaces of the base body I2 by suitable means such as screen printing.

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, includes a body 18.
is formed into a square flat plate shape between the base body 12 and the groove. The mating surface of the cap body 1B with the base 11 (
Hereinafter, it may be referred to as the bottom surface. ) A cavity recess 13b is arranged concentrically on the top, and is integrally formed with a recess shape similar to that larger than the cavity recess 13a of the base example and having a constant depth. There is. On the outer side of the cavity 13b on the mating surface of the cap body 18, a low temperature side low melting point glass layer 19 is made of the same material as the low temperature side low melting point glass coating layer 15 on the base side and is fired in advance. It is covered by this. That is, this cap low-temperature side low-melting point glass layer 19 is formed by applying a paste using an amorphous glass material of the same quality as the low-temperature side low-melting point glass layer 15 onto the mating surface of the cap body 1B by a suitable method such as screen printing. After being coated by suitable means, it is heated to 440° C. or higher and fired in a heating furnace, thereby being deposited 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 both low melting point glass coating layers 15 and 16 are in contact with the flat surface (hereinafter sometimes referred to as the lower surface) of the unit lead frame 2 on the side to which the aluminum coating is not applied. At the same time, they are arranged and set so that the opening edge of the cavity recess 13a is aligned with the tip group of the inner part 9a of the lead.

While maintaining the set state of the base 11 group, the multiple lead frame 1 is passed through a heating furnace at a temperature of about 500°C, which is the working temperature of the high-temperature side low-melting glass.
After the low temperature side low melting point glass coating layer 15 and the high temperature side low melting point glass coating layer 16 are melted, they are solidified. Along with this, the low temperature side low melting point glass coating layer 15 forms a low temperature side low melting point glass layer (hereinafter sometimes referred to as an amorphous glass layer).

) 15A and a high temperature side low melting point glass layer (hereinafter sometimes referred to as a crystalline glass layer) 16A are fired by the high temperature side low melting point glass coating layer 16, respectively. These amorphous glass layer 15A and crystalline glass layer 16A are welded and integrated with the base body 12 by firing.

At the same time, the inner portions 9a group of the unit lead frame 2 are mechanically fixed on the crystal glass layer 16A. The group of leads 9 are fixed by the crystal glass layer 16A in a state where they are reliably supported from below because the crystal glass layer 16A has mechanical strength.

In this way, for each unit lead frame 2, 1 base
A pellet bonding operation is performed for each unit lead frame 2, and then a wire bonding operation is performed on the multiple lead frame 1 to 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.

As a result of this bonding operation, as shown in FIGS. 9 and 10, the pellet 22 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 formed in each unit. It is brought into contact with the bonding floor 14 of the base 11 in the lead 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. Ru. At this time,
Since the 9 groups of leads in the unit lead frame 2 are mechanically supported by the crystalline glass layer 16A, they will not sink even if the amorphous glass layer 15A melts. The initial positional accuracy will be maintained.

Then, the pellet 22 bonded to the base 11
A wire 23 made of an aluminum 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. By using a bonder), both ends are bonded and bridged. At this time too,
The initial accuracy of the lead 9 group is maintained. Thereby, the integrated circuit built into the pellet 22 is electrically extracted to the outside via the electrode pad, the wire 23, and the inner part 9a and outer part 9b of the lead 9.

For each unit lead frame 2, there is 1 base.
1 was assembled, and the multiple lead frame 1 was sequentially subjected to pellet bonding and wire bonding operations. Sealing processing work is carried out.

That is, as shown in FIGS. 11 and 12, the cap 17 is oriented such that its low temperature side low melting point glass layer 19 is in contact with the upper surface of the unit lead frame 2 on the side opposite to the base 11. At the same time, the base 11 is covered and set in alignment with the base 11. While this set state is maintained, the base 11 and the cap 16 are
When the multi-lead frame 1 is passed through a heating furnace at approximately 435°C, which is the working temperature of the amorphous glass layers 15A and 19, while applying a suitable joining force between the base 1
By melting the amorphous glass layers 15A and 19 of the cap 16 and the cap 16, a sealing portion 2 made of the amorphous glass layer is formed.
4 is formed. As a result, base 11 and cap 16
The mating surfaces are sealed together by the glass sealing part 24,
A package 25 that hermetically seals the inside of the cavity 13 is formed.

At this time, the heating temperature for forming the glass sealing part 24 is a temperature at which the amorphous glass layers 15A and 19 soften;
That is, the temperature is set to 435°C or less. Therefore, the adverse effects of thermal stress on internal components such as the beret 22 and the wires 23 that have already been assembled to the base 11 of the hermetically sealed package 25 are suppressed.

In addition, since the temperature is below 460° C., which is the melting point of the crystal glass layer 16A, the crystal glass layer 16A does not soften.
The group of leads 9 is supported by this crystal glass layer 16A while maintaining the initial positional accuracy.

On the other hand, when the amorphous glass layers 15A and 19 reach a softening temperature, a reliable glass sealing portion 24 is stably formed. At this time, even if cracks or the like are formed in the crystalline glass layer 16A, these cracks or the like are reliably sealed by the molten amorphous glass layers 15A and 19.

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. Therefore, 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, the low-temperature side low melting point glass layers 15A and 19 are heated to 440°C or higher and are completely adhered to the surfaces of the base body 12 and the cap body 18, respectively. Even if the heating temperature in this sealing step is around the softening temperature, the surfaces of the base body 12 and cap body 18 and the glass sealing portion 2
The adhesion state between the base plate and the base plate 4 is safe, strong, and stable.

A multiple lead frame l on which the glass sealing portion 24 is formed and the hermetically sealed package 25 is formed as described above.
In the solder plating process, a solder plating film is entirely applied (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. In this way, the FPG shown in FIG.
This means that IC26 has been manufactured.

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

(1) By configuring the glass sealing part with two types of sealing glasses with different melting points, the high temperature side low melting point glass layer part to which the lead group is attached is not melted in the glass sealing part forming process. When the low melting point glass on the low temperature side is melted, the lead group is supported on the low melting point glass layer on the high temperature side, and as a result, the position of the lead group when attached to the low melting point glass on the high temperature side is Accuracy can be maintained, and on the other hand, the glass sealing portion can be appropriately molded by melting and solidifying the low melting point glass on the low temperature side.

(2) By maintaining the positional accuracy of the lead group during the molding process of a hermetically sealed pancage with a glass sealing part, the positional accuracy of the lead group with respect to the package in the height direction and pitch direction is improved. Therefore, it is possible to improve the quality and reliability of the hermetically sealed barragage by the glass sealing part.

(3) Before the pellets are assembled to the base, the low melting point glass layer formed on the base and cap is heated to a temperature above the melting point, so that the low melting point glass layer and the base and can knob surfaces are heated in advance. complete, and
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 pellets assembled to the base while ensuring the desired sealing performance. Therefore, the quality and reliability of the hermetically sealed package due to the glass sealing part can be improved.

The invention made by the present inventor has been specifically explained based on the examples above, but the present invention is based on the examples described above! It goes without saying that the present invention is not fixed and that various changes can be made without departing from the gist thereof.

For example, the material for forming the high temperature side low melting point glass layer is not limited to crystalline glass, but also low melting point glass made of amorphous glass that can secure a predetermined melting point temperature difference with respect to the low temperature side low melting point glass. etc. may also be used.

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 the FPG-IC1 and its manufacturing method, which is the background field of application, but the invention is not limited thereto. The present invention can be applied to all semiconductor devices, such as other ICs, which are equipped with a hermetically sealed package using a mounting portion.

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

By configuring the glass sealing part with two types of sealing glasses with different melting points, the high temperature side low melting point glass layer part to which the lead group is attached is not melted in the glass sealing part forming process, so the low temperature side low melting point glass layer part to which the lead group is attached is not melted. When the melting point glass is molten, the lead group is supported on the high temperature side low melting point glass layer, and as a result, the positional accuracy of the lead group when attached to the high temperature side low melting point glass is maintained. On the other hand, the glass sealing portion can be appropriately molded by melting and solidifying the low melting point glass on the low temperature side.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an FPG-IC which is an embodiment of the present invention, and Fig. 2 and subsequent figures show a method for manufacturing an FPG-IC which is an embodiment of the invention. The figure 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 bottom view showing the cap. Figures 7 and 8 are partially omitted plan views and front sectional views showing the base and lead frame after assembly. Figures 9 and 10 are the views after pellet and wire bonding. A partially omitted plan view and a front sectional view. FIGS. 11 and 12 are a partially omitted partially cutaway plan view and a front sectional view showing a multiple lead frame after molding a hermetically sealed package. 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, 11... Base, 12... Base copy 13a, 13b... Cavity recess, 13... Cavity 14... Ponding floor, 15...low temperature side low melting point glass coating layer, 15
A...low temperature side low melting point glass layer (amorphous glass layer), 1
6... High temperature side low melting point glass coating layer, 16A... High temperature side low melting point glass layer (crystalline glass layer), 17... Cap, 1B... Cap body, 19... Low temperature side low melting point glass layer (amorphous glass layer), 21... bonde ink layer, 22... pellet, 2309. 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 sealing glass. A semiconductor device comprising: a sealing portion formed between mating surfaces of the base and the cap to seal the base and the cap, and through which the lead group is passed, the sealing portion having a melting point. 1. A semiconductor device comprising two different types of sealing glass. 2. In the sealing part, crystalline glass is used as the low melting point glass on the high temperature side, and amorphous glass is used as the low melting point glass on the low temperature side.
1. Semiconductor device described in Section 1. 3. A method for manufacturing a semiconductor device according to claim 1, wherein two types of sealing glass having different melting points are respectively applied to regions corresponding to the sealing portions of at least one of the base and the cap. In the process, a group of leads is brought into contact with both of the glass coating layers, heated to a temperature higher than the melting point of the high temperature side low melting point glass, and the coating layer of the high temperature side low melting point glass is melted and solidified to form the above-mentioned glass layer. a step in which a group of leads is attached; a step in which a base and a cap are arranged and brought together so as to sandwich the group of leads, and are heated to a temperature equal to or higher than the low-temperature side low-melting point glass to form a sealed portion; A semiconductor manufacturing method characterized by comprising: