JPH11191608A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for preventing package cracks by increasing the package strength in a semiconductor device having thin resin-made package. SOLUTION: This device is constituted of a tab 1 encircled by a plurality of leads 2 is arranged at a position lower than a lead 2, a semiconductor chip 6 is fixed on the tab 1, and then a wire 9 is connected between a pad electrode 8 and an inner lead 2a as a front end part of the lead 2, while the tab 1, the wire 9 and the inner lead 2a of the lead 2 are encapsulated in a resin-made package 10. In this case, a thickness Z2 of the tab 1 is formed thinner than a thickness Z1 of the lead 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device in which a semiconductor chip fixed on a tab thereof using a lead frame is sealed with a resin package. Regarding effective technology.

[0002]

2. Description of the Related Art A resin-sealed semiconductor device is known as a kind of semiconductor device represented by an LSI (semiconductor integrated circuit device) such as a memory or a microprocessor. This resin-encapsulated semiconductor device uses a lead frame having a tab surrounded by a plurality of leads, and after fixing a semiconductor chip on the tab, a space between the pad electrode of the semiconductor chip and the tip of the lead is formed. Are connected (bonded) to the semiconductor chips, tabs, wires, and the ends of the leads are sealed with resin.

That is, a resin-sealed semiconductor device has a structure in which the whole is sealed by a so-called resin package, except for leads (outer leads) serving as external terminals. Such a resin-encapsulated semiconductor device is:
Utilization of a well-known transfer molding technique enables mass production and has an advantage that manufacturing cost is low. Therefore, it is applied to many semiconductor devices. In addition, resin-encapsulated semiconductor devices are incorporated in various electronic devices. As these electronic devices are required to be smaller and lighter, thinner resin packages are desired.

As a package structure suitable for such thinning, TSOP (Thin Small Outline Package),
TQFP (Thin Quad Flat Package), LQFP (Lowp
rofile Quad Flat Package) is known.

[0005] For example, a technique relating to the above TSOP is disclosed in "Nikkei Micro Device", published by Nikkei BP, June 1990, pages 32 to 62. This document describes an LSI composed of a resin package having a thickness of 1 mm.
It is shown.

By the way, in an LSI having such a thin resin package, when heat is applied such as reflowing a completed LSI or performing a temperature cycle test,
When the resin is sealed, the moisture trapped inside the package expands, and a package crack occurs.
This package crack is liable to occur particularly in a region having a small volume among upper and lower regions of the package centering on the semiconductor chip.

In order to prevent such package cracks, it is known that it is effective to make the volume of the package substantially equal in the upper and lower regions of the semiconductor chip. Therefore, in order to satisfy the above-described conditions, a so-called tab lowering is generally performed in which the position of the tab is lower than the position of the lead around the tab.
For example, FIG. 1 on page 47 of the above document shows an LSI having a tab-down structure. Here, the tabs and the leads have the same thickness because they are formed at the same time as the lead frame is formed from the conductive plate material by patterning.

[0008]

However, in the prior art as described above, since the tab is originally lowered inside the thin resin package, the resin thickness between the back surface of the tab and the lower end of the resin package is reduced. Since it is extremely thin, the strength of the resin package becomes insufficient. For this reason, when heat is applied such as reflowing the completed LSI or performing a temperature cycle test, thermal stress is applied particularly to the thin portion thereof.
There is still a problem that package cracks are likely to occur.

Further, recent tabs are known to have a so-called small tab structure or a cross tab structure. However, since these tabs have a large amount of tab lowering, the back surface of the tab and the resin package are not provided. Since the resin thickness with the lower end becomes thinner, the package strength becomes more insufficient.

It is an object of the present invention to provide a technique for improving the strength of a package and preventing a package crack in a semiconductor device having a thin resin package.

Another object of the present invention is to provide a technique for manufacturing a semiconductor device having a thin resin package and preventing cracking of the package without increasing the cost.

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

[0013]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

(1) In the semiconductor device of the present invention, a tab surrounded by a plurality of leads is arranged at a position lower than the leads, a semiconductor chip is fixed on the tab, and a pad electrode of the semiconductor chip is connected to the tab. A wire is connected between the tip of the lead and the semiconductor chip, the tab,
In a semiconductor device in which a tip of the wire and the lead is sealed with a resin package, a thickness of the tab is formed smaller than a thickness of the lead.

(2) In the semiconductor device according to the present invention, in the semiconductor device according to (1), the volume of the resin package in the upper and lower regions of the semiconductor chip is substantially equal.

(3) In the semiconductor device according to the present invention, in the semiconductor device described in (1) or (2), the tab has a circular or square structure whose periphery is supported by a tab suspension lead.

(4) In the semiconductor device according to the present invention, in the semiconductor device according to (1) or (2), the area of the tab is smaller than the area of the semiconductor chip.

(5) In the semiconductor device according to the present invention, in the semiconductor device according to (1) or (2), the tab is wider than the width of the tab suspension lead, the end of which is supported by the tab suspension lead. Has a crossed structure.

(6) The method of manufacturing a semiconductor device according to the present invention comprises:
(A) patterning a conductive plate material to form a lead frame having at least a tab for fixing a semiconductor chip and a plurality of leads surrounding the tab, and then processing the tab to be thinner than the thickness of the lead; (B) lowering the lead frame so that the tab is at a position lower than the lead; (c) fixing a semiconductor chip on the tab; (d) pad electrode of the semiconductor chip and the semiconductor chip. (E) sealing the semiconductor chip, the tab, the wire, and the tip of the lead with a resin package.

(7) The method of manufacturing a semiconductor device according to the present invention
(6) In the method for manufacturing a semiconductor device according to (6), in the step (a), the processing of making the tab thinner than the thickness of the lead is performed by an etching method or a pressing method.

(8) The method of manufacturing a semiconductor device according to the present invention comprises:
In the method for manufacturing a semiconductor device according to (6) or (7), the step (b) is performed by a pressing method.

(9) The method of manufacturing a semiconductor device according to the present invention comprises:
In the method for manufacturing a semiconductor device according to any one of (6) to (8), the step (e) is performed so that the volumes of the resin packages in the upper and lower regions of the semiconductor chip are substantially equal.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a top perspective view showing a semiconductor device according to Embodiment 1, and FIG.
It is arrow sectional drawing.

For example, a tab 1 made of an Fe (iron) -Ni (nickel) alloy material is surrounded by a plurality of leads 2 made of the same material, and the tab 1 is lower than the leads 2 by a height h. So-called tab lowering is performed. The tab 1 is formed in, for example, a circular structure whose periphery is supported by the tab suspension leads 3. However, this structure may be formed in a square shape. The tab suspension lead 3 is integrally connected to the lead frame main body 4. The plurality of leads 2 are also integrally connected to the lead frame main body 4 via dam bars 5 formed in a direction orthogonal to the leads 2.

The lead 2 is formed by integrally connecting an inner lead 2a disposed inside the dam bar 5 and an outer lead 2b disposed outside the dam bar 5, and the outer lead 2b is used as an external terminal. .
In FIG. 1, the dam bar 5
However, in an actual finished product, the dam bar 5 is cut and the leads 2 are electrically insulated.

Here, the lead 2, the tab suspension lead 3, the lead frame body 4, the dam bar 5, etc.
When a lead frame is patterned and formed by an etching method or a press method using a conductive plate material made of an e (iron) -Ni (nickel) alloy material, the lead frame is formed at the same time. Has become. A plate having a thickness of about 0.125 mm is used as an example.

In the present embodiment, the thickness Z ₂ of the tab 1 is
Is formed to be thinner than the thickness Z ₁ lead 2 consisting of the inner leads 2a and outer leads 2b. The thickness Z ₂ of the tab 1 is basically equal to the thickness Z ₁ of the lead 2 (for example, 0.
(Approximately 125 mm), it is more effective. The minimum thickness is determined by the processing accuracy of processing the tab 1 to be thin, but several μm is possible by using the current processing technique by the etching method or the press method.

A semiconductor chip 6 (for example, about 250 to 330 μm in thickness) made of, for example, single crystal silicon is provided on the tub 1 via an adhesive 7 (for example, about 30 μm in thickness) such as Ag (silver) paste. Fixed. Tab 1
Is formed smaller than the area of the semiconductor chip 6 and has a so-called small tab structure. A wire 9 made of, for example, an Au (gold) wire or the like is connected (bonded) between the pad electrode 8 of the semiconductor chip 6 and the inner lead 2 a which is the tip of the lead 2. The height of the uppermost end of the wire 9 is 2 mm from the surface of the semiconductor chip 6.
It is kept at about 00 μm.

The semiconductor chip 6, the tab 1, the wire 9, and the inner lead 2a, which is the tip of the lead 2, are sealed by a resin package 10 made of, for example, epoxy resin and having a thickness of about 1 mm.

[0031] Thus, in molded with a resin-made package 10, the thickness Z ₂ of the tab 1 is formed thinner than the thickness Z ₁ of the lead 2, at the upper and lower region of the semiconductor chip also in the package volume is lowered tab to be substantially equal structures, it is possible to increase amount with a reduced tab 1 than conventional distance Z ₀ between the lower end of the back surface and the resin package 10 of the tab 1. That is, the resin thickness can be increased. Therefore,
Since the strength of the resin package can be improved, a margin for thermal stress can be increased, so that a package crack can be prevented.

Next, a method of manufacturing a semiconductor device having the above-described structure will be described with reference to FIGS.

First, as shown in FIG.
(Iron) -Ni (nickel) alloy material with a thickness of 0.1
A conductive plate material 11 of about 25 mm is prepared. Next, FIG.
As shown in FIG. 1, the conductive plate 11 is patterned by etching or pressing to form a tub 1 for fixing a semiconductor chip, and inner tabs 2 arranged around the tub 1.
The lead frame 12 having the lead 2 and the like formed of the outer lead 2b and the outer lead 2b is formed. Here, the tab 1 is formed in a so-called small tab structure so that the planar area is smaller than the area of the semiconductor chip fixed thereon.

Next, as shown in FIG. 5, the tab 1 of the lead frame 12 is processed by an etching method such as half-etching or a press method such as half-pressing (coining) to form the lead 2 around the lead. Thickness Z
_It is formed to have a thickness Z ₂ (Z ₁ > Z ₂ ) smaller than ₁ . The thickness Z ₂ of the tab 1 is basically the thickness Z of the lead 2.
_It is sufficient that the thickness is smaller than ₁ (for example, about 0.125 mm). The minimum thickness is determined by the processing accuracy of processing the tab 1 to be thin, but several μm is possible by using the current processing technique by the etching method or the press method.

Next, as shown in FIG. 6, the tab 1 of the lead frame 12 is processed by, for example, a press method, and the tab is lowered to a position lower than the position of the lead 2. The amount h of tab lowering is selected so that the volumes of the resin package formed in the subsequent resin sealing step in the upper and lower regions of the semiconductor chip are substantially equal.

Next, as shown in FIG. 7, a semiconductor chip 6 (thickness;
(About 250 to 330 μm) is fixed via an adhesive 7 (thickness: about 30 μm) such as an Ag (silver) paste.

Next, as shown in FIG.
A wire 9 made of, for example, an Au (gold) wire or the like is connected (bonded) between the pad electrode 8 and the inner lead 2a which is the tip of the lead 2. In this case, wire 9
Is 200 μm from the surface of the semiconductor chip 6.
It is controlled so as to be kept to the extent. This prevents the uppermost end of the wire 9 from being exposed to the outside from a resin package formed in a later resin sealing step.

Next, as shown in FIG. 2, the semiconductor chip 6, the tab 1, the wire 9, and the inner lead 2a which is the tip of the lead 2 are formed by resin molding the lead frame 12 by transfer molding. The package is sealed with a resin package 10 made of epoxy resin and having a thickness of about 1 mm. Thus, the distance Z ₀ between the lower end of the back surface and the resin package 10 of the tab 1, than conventional thin tabs 1 minute (Z ₁ -Z ₂₎ only increases.
At the time of this resin molding, as shown in FIG. 1, since the dam bar 5 is provided so as to connect the respective leads 2, the resin is blocked by the dam bar 5, so that the resin flows into the outer lead 2 b. Absent. Subsequently, the semiconductor device is completed by cutting the dam bar 5 and forming the outer lead 2b into a gull-wing shape.

According to the present embodiment, in a semiconductor device sealed by a resin package 10, the thickness Z ₂ of the tab 1 is formed thinner than the thickness Z ₁ of the lead 2, the semiconductor chip In the structure in which the tabs are lowered so that the volume of the resin package 10 in the upper and lower regions of the resin package 10 is substantially equal, the back surface of the tab 1 and the resin package 1
The distance Z ₀ from the lower end of 0 can be increased by the thickness of the tab 1 as compared with the conventional case. Therefore, since the strength of the resin package can be improved, the margin for the thermal stress can be increased, so that the package crack can be prevented.

Further, this semiconductor device can be easily manufactured by using a well-known etching method or press method without using any special manufacturing process, so that it can be manufactured without increasing the cost.

(Embodiment 2) In this embodiment, an example in which a tab is applied to a semiconductor device having a so-called cross-tab structure will be described with reference to FIGS. 9 and 10. FIG.

FIG. 9 is a top perspective view showing a semiconductor device, and FIG.
0 is a sectional view taken along the line AA in FIG. That is, FIG.
As shown in FIG. 2, the tab 13 formed at the same time as the formation of the lead frame made of the same material as the tab 1 in the first embodiment is supported at the end by the tab suspension lead 14, and has a width W1 of the tab suspension lead 14. Wider width W2 than
Are formed in a crossed structure. The tab 13 is surrounded by a plurality of leads 16 and is lowered to a position lower than the leads 16 by a height h.

The thickness Z ₂ of the tab 13 is smaller than the thickness Z _{1 of the} lead 16 composed of the inner lead 16a and the outer lead 16b, as in the first embodiment. The thickness Z ₂ of the tab 13 is basically sufficient if thinner than the thickness Z ₁ of the lead 16 (for example, about 0.125 mm), a thinner effective. This minimum thickness is determined by the processing accuracy of processing the tab 13 to be thin, but several μm is possible by using the current etching or pressing processing technology.

On the tab 13, as in the first embodiment,
For example, a semiconductor chip 6 (thickness dimension: about 250 to 330 μm) made of single crystal silicon is fixed via an adhesive 7 (thickness dimension: about 30 μm) such as an Ag (silver) paste, and a pad of the semiconductor chip 6 is formed. Electrode 8 and lead 1
A wire 9 made of, for example, an Au (gold) wire or the like is connected (bonded) between the inner lead 16a, which is the tip of the wire 6, and the like. The height of the uppermost end of the wire 9 is kept at about 200 μm from the surface of the semiconductor chip 6.

The semiconductor chip 6, tab 1, wire 9
And an inner lead 16a which is a tip of the lead 16.
Is sealed by a resin package 17 made of, for example, epoxy resin and having a thickness of about 1 mm.

Next, a method for manufacturing a semiconductor device having the above-described structure will be described with reference to FIGS.

First, similarly to the process shown in FIG. 3, the thickness of a material made of, for example, an Fe (iron) -Ni (nickel) alloy is used.
A conductive plate material 11 of about 0.125 mm is prepared. next,
As shown in FIG. 11, a tab 13 for fixing the semiconductor chip by patterning the conductive plate material 11 by an etching method or a pressing method, a lead 16 disposed around the tab 13 and including an inner lead 16a and an outer lead 16b, etc. Is formed. Here, the end of the tab 13 is supported by the tab suspension lead 14, and a pair of band-shaped members 15 having a width W2 wider than the width W1 of the tab suspension lead 14 crosses the tab 13.
It is formed in a so-called cross-tab structure.

Next, as shown in FIG. 12, the tab 13 of the lead frame 18 is processed by an etching method such as half-etching or a press method such as half-press (coining) to form the lead 16 around the lead frame 18. It is formed to have a thickness Z ₂ (Z ₁ > Z ₂ ) smaller than the thickness Z ₁ . The thickness Z ₂ of the tab 13 is basically the same as that of the lead 16.
The thickness may be smaller than the thickness Z ₁ (for example, about 0.125 mm), but the thinner, the more effective. This minimum thickness is determined by the processing accuracy of processing the tab 13 to be thin, but several μm is possible by using the current etching or pressing processing technology.

Next, as shown in FIG. 13, the tab 13 of the lead frame 18 is processed by, for example, a press method, and the tab is lowered to a position lower than the position of the lead 16. The amount h of tab lowering is selected so that the volumes of the resin package formed in the subsequent resin sealing step in the upper and lower regions of the semiconductor chip are substantially equal.

Next, as shown in FIG. 14, a semiconductor chip 6 made of, for example, single crystal silicon (having a thickness of about 250 to 330 μm) is formed on the tub 1 by an adhesive 7 such as an Ag (silver) paste. After fixing the semiconductor chip 6 through a pad electrode 8 of the semiconductor chip 6 and an inner lead 16a which is a tip of the lead 16, for example, an Au (gold) wire or the like is used as shown in FIG. Are connected (bonded). In this case, the height of the uppermost end of the wire 9 is 200 μm from the surface of the semiconductor chip 6.
m so as to prevent the top end of the wire 9 from being exposed to the outside from a resin package formed in a later resin sealing step.

Next, the lead frame 18 is resin-molded by the transfer molding method, and as shown in FIG. 10, the semiconductor chip 6, the tab 13, the wire 9 and the inner lead 16a which is the tip of the lead 16 are made of, for example, epoxy. Resin package 1 about 1mm thick made of resin
7 seal. Thus, the distance Z ₀ between the lower end of the back surface and the resin package 17 of the tab 13, than conventional thin tabs 13 min (Z ₁ -Z ₂₎ only increases.
At the time of this resin molding, as shown in FIG.
Since the dam bar 5 is provided so as to connect the space therebetween, the resin is blocked by the dam bar 5, so that the resin does not flow into the outer lead 16b. continue,
The semiconductor device is completed by cutting the dam bar 5.

According to the present embodiment, in the semiconductor device sealed by resin package 17, only the tab is replaced with the cross tab structure from the small tab structure as compared with the first embodiment. The thickness Z ₂ is the lead 16
It is formed to be thinner than the thickness Z ₁ of the. Therefore, even in a structure in which the tabs are lowered so that the volumes of the resin package 17 in the upper and lower regions of the semiconductor chip 6 are substantially equal, the distance Z ₀ between the back surface of the tab 13 and the lower end of the resin package 17 is set to be larger than that of the conventional case. Since 1 can be increased by reducing the thickness, the strength of the resin package can be improved, the margin for thermal stress can be increased, and package cracks can be prevented.

Further, since this semiconductor device can be easily manufactured by using a well-known etching method or press method without using any special manufacturing process, it can be manufactured without increasing the cost.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the scope of the invention. Needless to say, it can be changed.

For example, the materials and thickness dimensions of the tabs or leads described in the above embodiment are merely examples, and the present invention is not limited to this. Other good materials can be used.
Also, the thickness dimension depends on the size of the resin package,
Can be changed.

Further, the tab structure is not limited to the small tab or cross tab structure, but can be applied to a structure in which a part thereof is deformed.

The semiconductor chip fixed on the tub is not limited to a specific element, but can be applied to all LSI chips.

[0058]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) In a semiconductor device having a thin resin package, the strength of the package can be improved and package cracks can be prevented.

(2) A semiconductor device having a thin resin package and preventing cracking of the package can be manufactured without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a top perspective view showing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 4 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 5 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 6 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 7 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 8 is a sectional view illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 9 is a top perspective view illustrating a semiconductor device according to a second embodiment of the present invention;

FIG. 10 is a sectional view taken along the line AA of FIG. 9;

FIG. 11 is a sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment of the present invention;

FIG. 12 is a sectional view illustrating the method of manufacturing the semiconductor device according to the second embodiment of the present invention;

FIG. 13 is a sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment of the present invention;

FIG. 14 is a cross-sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment of the present invention;

FIG. 15 is a sectional view illustrating the method of manufacturing the semiconductor device according to the second embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tab (small tab) 2 Lead 2a Inner lead 2b Outer lead 3 Tab suspension lead 4 Lead frame main body 5 Dam bar 6 Semiconductor chip 7 Adhesive 8 Pad electrode 9 Wire 10 Resin package 11 Conductive plate 12 Lead frame 13 Tab (cross tab ) 14 tab suspension leads 15 strips 16 lead 16a inner leads 16b outer lead 17 resin package 18 leadframe Z ₀ of the distance Z ₁ leads to the lower end of the tab of the back surface and the resin package thickness Z ₂ tabs thickness h Tab lowering amount W1 Width of tab suspension lead W2 Width of band member for cross tab

Claims (9)

[Claims] A tab surrounded by a plurality of leads is disposed at a position lower than the leads, and a semiconductor chip is fixed on the tabs and between a pad electrode of the semiconductor chip and a tip of the leads. A tip of the semiconductor chip, the tab, the wire, and the lead are sealed with a resin package, wherein the thickness of the tab is greater than the thickness of the lead. A semiconductor device which is formed to be thin. 2. The semiconductor device according to claim 1, wherein the volume of the resin package in a region above and below the semiconductor chip is substantially equal. 3. The semiconductor device according to claim 1, wherein the tab has a circular or square structure whose periphery is supported by a tab suspension lead. 4. The semiconductor device according to claim 1, wherein an area of the tub is smaller than an area of the semiconductor chip. 5. The semiconductor device according to claim 1, wherein the tab is formed by a pair of band-shaped members each having a width larger than the width of the tab suspension lead, the end of which is supported by the tab suspension lead. A semiconductor device having a structure as described above. 6. (a) patterning a conductive plate material,
A step of forming a lead frame having at least a tab for fixing a semiconductor chip and a plurality of leads surrounding the tab, and then processing the tab to be thinner than the thickness of the lead; Lowering the tab so that it is lower than the lead, (c)
Fixing a semiconductor chip on the tab, (d) connecting a wire between a pad electrode of the semiconductor chip and a tip of the lead, and (e) connecting the semiconductor chip, the tab, the wire and the wire. A method of manufacturing a semiconductor device, comprising a step of sealing a tip portion of a lead with a resin package. 7. The method of manufacturing a semiconductor device according to claim 6, wherein, in the step (a), the process of making the tab thinner than the thickness of the lead is performed by an etching method or a press method. Manufacturing method of a semiconductor device. 8. The method for manufacturing a semiconductor device according to claim 6, wherein the step (b) is performed by a press method. 9. The method of manufacturing a semiconductor device according to claim 6, wherein the step (e) is performed such that a volume of the resin package in a region above and below the semiconductor chip is substantially equal to that of the semiconductor chip. A method for manufacturing a semiconductor device, wherein the steps are performed so as to be equal.