JP3173250B2 - Method for manufacturing resin-encapsulated semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the up and down movement and the inclination of a semi conductor chip with the pressure of molten resin, which is injected into a forming metal mold. CONSTITUTION:A plurality of protruding parts 30 of resin or metal having the height corresponding to the thickness of sealing resin 12 is provided on the surface and/or rear surface of a semiconductor chip, or on the rear surface of the die pad of a lead frame. The end part of the protruding parts 30 are brought into contact with cavity faces 43A and 44A of upper and lower metal molds 43 and 44 of a forming metal mold. Under this state, molten resin M is injected, and resin sealing is performed. Therefore, the stay shift of the semiconductor chip can be suppressed by the presence of a plurality of the protruding parts 300. Therefore, wire breakdown can be prevented, the contact of inner leads and the edge of the semiconductor chip 10 can be avoided and the yield rate is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-encapsulated semiconductor device (hereinafter, simply referred to as an "IC chip") in which an electronic circuit is integrated and formed by a transfer molding method. (Hereinafter simply referred to as “IC”).

[0002]

2. Description of the Related Art First, a conventional IC and a resin sealing method thereof will be described with reference to FIGS. FIG. 7 is a cross-sectional view of a semiconductor chip, a sealing mold, and the like showing one resin sealing step of a conventional method of manufacturing an IC, and FIG. 8 is an inconvenience caused in the resin sealing step shown in FIG. FIG. 9 is a cross-sectional view of a semiconductor chip, a molding die, and the like for describing a state. FIG.
FIG. 2 is a cross-sectional view of an IC showing an example of a defect that can occur in
FIG. 10 is a cross-sectional view of an IC showing another example of a defect that can occur in the IC manufactured by the resin sealing process shown in FIG. 7, and FIG. FIG. 12 is a cross-sectional view showing a process, FIG. 12 is a cross-sectional view of an IC manufactured by the resin sealing process shown in FIG. 7, and FIG. 13 is a resin-sealed semiconductor device manufactured by the manufacturing method of the present invention. And FIG. 12 is a graph showing a comparison of a change in data holding voltage depending on the presence or absence of external light irradiation when a memory device is mounted as a semiconductor chip in a resin-encapsulated semiconductor device manufactured by the conventional manufacturing method shown in FIG. It is.

[0003] Resin sealing of a conventional IC is usually performed using a molding die as shown in FIG. This molding die includes an upper die 1 and a lower die 2, and seals the IC chip 10 placed between the two upper and lower dies 1, 2 in a resin molded package of a predetermined shape. Cavities 1A and 2A, and a gate portion 4 serving as an inlet to each of the cavities 1A and 2A from a runner 3 serving as a passage for the molten resin. Reference numeral 13 indicates a wire such as a gold wire, and reference numeral 14 indicates a part of a lead frame.

When performing resin molding using such a molding die, molten sealing resin is injected from the gate portion 4 and the runner portion 3 on one side of the cavities 1A and 2A. When the molten resin is injected, the IC chip 10 and a semiconductor chip mounting portion (hereinafter, referred to as a die pad) 11 on which the IC chip 10 is mounted are provided.
However, as shown in FIG. 8, a so-called stay shift, which may move up and down or tilt from a design position due to the pressure of the injected molten resin M, may occur.

In particular, in recent years, the degree of integration of electronic circuits has increased,
Accordingly, the area of the IC chip 10 also increases, and
The area of the die pad 11 has also become larger than before. On the other hand, the number of pins of the IC is increasing, the pitch between the external leads is becoming narrower, and accordingly, the width of the support bar suspending the internal leads and the die pad 11 is becoming thinner and longer. With such a structure, the IC chip 10 and the die pad 11 undergo a stay shift even with a slight resin pressure.

Further, in recent years, in the IC having a floating chip structure which has been developed for the purpose of thinning, the die pad 11 does not exist in the lead frame. Occurs more frequently in comparison.

When the stay shift of the IC chip 10 and its die pad 11 is severe, On the IC chip 10 or its die pad 11
Below (IC chip 1 for floating chip structure)
(Below 0), the space in which the sealing resin is sealed is narrowed, so that the fluidity of the molten resin M deteriorates, and unfilled or voids are generated on the surface of the injected molten resin M. 2. The balance of the vertical cross-sectional structure of the IC is lost, and the IC package is warped due to the difference in the coefficient of thermal expansion between the internal constituent materials. Furthermore, especially when the IC chip 10 is lifted upward, as shown by reference numeral 3A in FIG.
Wire 1 bonding between lead 0 and lead 14
3 is exposed on the surface of the sealing resin 12. When the position of the bonding point on the IC chip 10 further rises, the wire 13 falls down and touches the edge of the IC chip 10 as shown by reference numeral 13B in FIG. Further, as shown in FIG. 13C, the wire 13 may be pulled and disconnected, causing various troubles.

[0008]

SUMMARY OF THE INVENTION In order to suppress such a stay shift that causes a fatal defect, Japanese Patent Laid-Open Publication No. Hei.
7848, the invention disclosed in JP-A-3-9538, or the patent application No. 4 filed on July 13, 1992 by the present applicant.
In the invention described in 184854, as shown in FIG. 11, in the molding die for IC, the upper die 1 and the lower die 2
And a fixed or movable vertical movement preventing pin 16 for holding the IC chip 10 therebetween. JP-A-4-7
In the invention disclosed in FIG. 848, as shown in FIG.
Pin marks 17 remain on the surface of the C package 10, and depending on the case, the thickness of the resin at that portion, particularly on the surface side of the IC chip 10, becomes thin, or the surface of the IC chip 10 is exposed. May be.

When the IC enters such a state, a new
The following matters are problems. That is, A. Since pin traces 17 remain on the surface of the sealing resin 12,
This is a cosmetic problem. B. The mechanical strength of the sealing resin 12 decreases. C. Moisture or the like enters the inside of the sealing resin 12 from the location of the pin mark 17, which lowers the reliability of the IC. D. At the pin mark 17, the resin on the IC chip 10 is extremely thin, and in some cases, the surface of the IC chip 10 is exposed. The electric properties of the IC may be impaired by reaching the surface of the chip 10 and being affected by the energy of the light. For example, if the IC is a memory device,
As shown by the dotted line B in FIG. 13, the data holding voltage rises and the data stored in the memory device disappears. In this case, the original function of the IC is impaired, and normal operation cannot be performed.

As described above, when the pin mark 17 remains on the surface of the sealing resin 12, a new problem occurs. To eliminate the problem, the applicant of the present invention filed on February 17, 1993. The invention of Japanese Patent Application No. 5-52890 attempts to solve the above-mentioned problems by filling the traces of pins remaining on the package surface with resin or metal. Also, JP-A-3-953
8 or in the invention disclosed in Japanese Patent Application No. 4-184854 filed on July 13, 1992, the projecting pin of the molding die is made movable, and the timing is adjusted at the time of resin sealing. While pulling in this pin, IC
Pin marks are not left on the surface of the package 12.

However, in these embodiments of the present invention, when the resin is sealed, the pin for preventing the vertical movement of the molding die is basically an IC.
It often contacts the surface of the chip 10,
The surface of the IC chip may be damaged. For example,
If the portion damaged by the vertical movement prevention pin is the uppermost layer of the passivation film on the surface of the IC chip, the penetration of moisture or impurity ions from the damaged portion causes
The underlying aluminum wiring may be corroded. Further, when the damage itself further reaches the internal aluminum wiring or the like, a shift in wiring, a structural defect, or the like causes a leak current or a short circuit phenomenon. When such a phenomenon occurs, the IC no longer operates normally.

[0012]

SUMMARY OF THE INVENTION Therefore, an IC of the present invention is provided.
In the case of a lead frame having a die pad, one a collision Okoshibutsu formed on one surface of the semiconductor chip,
Further, a projection is formed on the other surface of the semiconductor chip or on the semiconductor chip mounting portion . The other one is for semiconductor chips
Form protrusions. In any case, the surface on which the protrusion is formed is directed downward, and at this time, the latter protrusion is formed while holding the semiconductor chip on a stage in which a recess is formed to avoid the already formed protrusion. The above-mentioned problem has been solved, for example, the semiconductor chip fits in the cavity via the protrusion without being moved, and does not deform during resin sealing.

[0013]

Accordingly, I present in the cavity of the molding die.
Even if the C chip has a speed difference in the flow of the molten resin injected into the molding die, the movement of the IC chip is restricted by the plurality of protrusions even if the IC chip is moved upward or downward. Will be done. Although a slight boundary is formed between the protrusion and the sealing resin, holes, burrs, and the like as seen in the prior art do not remain on the surface of the sealing resin of the IC.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an IC according to the present invention and a method for manufacturing the same will be described below with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a first step of forming protrusions on a semiconductor chip mounted on a lead frame, showing a state before resin sealing for obtaining an IC according to the present invention, FIG.
FIG. 4 is a cross-sectional view showing a second step following the step shown in FIG. 1, FIG. 3 is a cross-sectional view showing another method for forming a projection on a semiconductor chip, and FIG. FIG. 5 is a cross-sectional view of a state in which the semiconductor chip on which the protrusions are formed in the step 3 is housed in a molding die, and FIG. 5 is a manufacturing method of the present invention obtained by completely resin-sealing the state of FIG. FIG. 2 is a cross-sectional view of an IC obtained by the above method.

FIG. 6 shows a state before resin encapsulation for obtaining an IC by the manufacturing method of the present invention, and shows another step of forming a projection on a semiconductor chip mounted on a lead frame. It is sectional drawing which showed.

First, the manufacturing method of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 shows an IC chip 10 of the present invention.
Is shown in a state where the lead frame on which is mounted is mounted on the stage 61. The IC chip 10 includes a die pad 11, a plurality of leads 14 formed on a peripheral portion of the die pad 11, and a normal lead frame including other components.
A plurality of electrode pads 15 formed on the surface of the IC chip 10 are connected to the inner ends of the respective leads 14 by wires 13.

The potting resin 31 is dropped on the surface of the IC chip 10 in such a state using the nozzle 60. Thereafter, a heat treatment is applied to the potting resin 31.
To cure. The height of the cured protruding resin (hereinafter, simply referred to as “protrusion 31A”) is the height of the sealing resin 12 (FIG. 1) required above the IC chip 10 and below the die pad 11.
The minimum thickness of 1) is secured, and each sealing resin 1
The thickness may be equal to or slightly smaller than the designed thickness of 2. The height of the projection 31A is adjusted by adjusting the application conditions according to the viscosity of the potting resin 31 to be applied.

When the potting resin 31 is dropped on the back surface of the die pad 11 (the IC chip 10 in the case of a floating chip structure, the same applies hereinafter), the lead frame may be turned upside down in the same manner as described above. When the protrusion 31A is formed on the surface of the IC chip 10 first, it is preferable to use a stage 61A on which a relief 62 is formed as shown in FIG.

A projection 31B made of resin is formed on the back surface of the die pad 11 in advance, and then, as shown in FIG. 3, a stage 61B provided with a plurality of reliefs 62 is used.
A lead frame may be placed on the stage 61B with the projections 31B inserted into these clearances 62, and the potting resin 31 may be applied on the IC chip 10 on which the die pad 11 is mounted.

Thereafter, as shown in FIG. 4, the lead frame is sandwiched between the upper mold 1 and the lower mold 2, and the molten resin M is injected from the runner 3 and the gate 4 to perform resin sealing. After the molten resin M is cured, the IC 52 of the present invention as shown in FIG. 5 can be obtained by taking it out of the molding die.

An example in which the projection is formed of metal will be described. In this example, it is intended to prevent a stay shift of the IC chip 10 by attaching a metal projection 31C having an appropriate height on the surface of the IC chip 10. The projection 31C is formed by bonding a metal ball formed at the time of performing wire bonding to a dummy pad (not shown) provided on the surface of the IC chip 10 in advance, and using this as a projection 31C. Things.

That is, as shown in FIG. 6, for example, a gold ball 66A is formed at the tip of a gold wire 66 by a wire bonding apparatus 63 including a wire clamper 64, a capillary 65 and the like. After applying an appropriate load to the gold ball 66A and bonding it to the dummy pad, the opening and closing of the wire clamper 64 and the capillary 65
By this movement, the gold ball 66A can be cut, and the gold protrusion 31C can be formed on the surface of the IC chip 10. Similarly, such protrusions 31C can be formed on the back surface of the IC chip 10.

An IC having such a projection 31C formed thereon
As shown in FIG. 4, the chip 10 is divided into an upper mold 1 and a lower mold 2.
Then, it is housed and fastened in a molding die consisting of: And after hardening of the sealing resin 12,
The IC 53 shown in FIG. 5 can be obtained from the molding die.

The method of determining the height of the gold ball 66A is the same as the design thickness of the upper and lower sealing resins, or a value slightly smaller than the thickness. Alternatively, on the contrary, the value may be set to a slightly larger value, and as shown in FIG. 4, when sandwiched between the upper and lower dies, the metal ball 66A may be slightly crushed by the die. In this case, there is an advantage that the portions of the IC chip 10 and the die pad 11 are more firmly fixed in the mold during resin sealing. In any case, the gold ball 66A of the IC chip 10 can be set to a predetermined height by adjusting the bonding conditions such as the initial ball diameter and the load.

In the IC 53 of this embodiment, the IC chip 1
The protrusion 31 bonded to the front surface of the IC package 12 and the back surface of the die pad 11 may be exposed on the front surface and the back surface of the IC package 12, but there is no problem in reliability. In this embodiment, the protrusion 31C is made of gold. However, when the wire bonding method is used, copper can be used as the metal. Furthermore, as a method of forming metal protrusions on the surface of the IC chip 10, in addition to a method using a conventional wire bonding technique, a forming method using a vapor deposition method, a sputtering method, a plating method, or the like may be applied. Can be.

[0026]

Advantages of the Invention As described above, the use of the IC chip according to the manufacturing method of the present invention makes it possible to control the position inside the package, which is the sealing resin. As a result, 1) unfilling and void generation on the package surface 2) package warpage 3) exposure of the bonding wire to the package surface 4) short-circuit failure (the bonding wire touches the edge of the chip) 5) the bonding wire Problems such as disconnection can be reduced. Also,

1. The position control of the IC chip can be performed without providing a vertical movement preventing pin on a molding die, especially on the upper die. As a result, no pin mark remains on the resin package. As a result, 1) the problem of the appearance of the package is reduced. 2) The decrease in the mechanical strength of the package can be reduced. 3) The penetration of moisture or the like into the package is reduced, and the reliability of the IC is reduced. 4) Since the incidence of light from the outside is suppressed, effects such as not adversely affecting the electrical characteristics of the IC (see the solid line A in FIG. 13) can be obtained. Furthermore,

2. The position of the IC chip was controlled so that the surface of the IC chip was not damaged by a protrusion on the mold. Therefore, inconvenience such as impairing the original function of the IC can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first step of forming protrusions on a semiconductor chip mounted on a lead frame in a state before resin sealing for obtaining an IC according to the present invention.

FIG. 2 is a cross-sectional view showing a second step following the step shown in FIG.

FIG. 3 is a cross-sectional view showing another method for forming a protrusion on a semiconductor chip.

FIG. 4 is a cross-sectional view of a state in which the semiconductor chip on which the protrusions are formed in the steps of FIGS.

5 is a cross-sectional view of an IC according to the present invention obtained by completely resin-sealing from the state of FIG.

FIG. 6 is a cross-sectional view showing another example in which protrusions are formed on a semiconductor chip mounted on a lead frame in a state before resin sealing for obtaining an IC according to the present invention.

FIG. 7 is a cross-sectional view of a semiconductor chip, a sealing mold, and the like showing a resin sealing step in a conventional method of manufacturing an IC.

8 is a cross-sectional view of a semiconductor chip, a molding die, and the like for explaining an inconvenient state generated in the resin sealing step shown in FIG.

9 is a cross-sectional view of the IC showing an example of a possible defect in the IC manufactured by the resin sealing step shown in FIG. 7;

FIG. 10 is a cross-sectional view of the IC showing another example of a defect that can occur in the IC manufactured by the resin sealing process shown in FIG. 7;

FIG. 11 is a cross-sectional view showing one resin sealing step of another conventional method of manufacturing an IC.

FIG. 12 is a sectional view of an IC manufactured by the resin sealing step shown in FIG. 7; It is sectional drawing which showed the manufacturing process of the conventional resin sealing type semiconductor device.

FIG. 13 shows a memory device mounted as a semiconductor chip in the resin-sealed semiconductor device manufactured by the manufacturing method of the present invention and the resin-sealed semiconductor device manufactured by the conventional manufacturing method shown in FIG. 7; 6 is a graph showing a comparison of a change in data holding voltage depending on the presence or absence of external light irradiation in the case.

[Explanation of symbols]

1 upper mold, 1A cavity, 2A cavity, 2
... lower mold, 10 ... semiconductor chip (IC chip), 11 ...
Die pad, 12 sealing resin, 13 wire, 14 lead, 17 pin trace, 30 protrusion, 31 potting resin, 31A protrusion, 31B protrusion, 31C
Projection, 53 ... IC, 60 ... Nozzle, 61 ... Stage,
61A: Stage, 62: Escape, 63: Wire bonding device, 64: Wire clamper, 65: Capillary, 66: Gold wire, 66A: Gold ball

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Makoto Ito 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-4-165634 (JP, A) JP-A 5-267369 (JP, A) JP-A-5-90315 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/56, 23/28

Claims (2)

(57) [Claims] A projection is formed on one surface of a semiconductor chip, and when the projection is formed on another surface of the semiconductor chip or on a semiconductor chip mounting portion, the surface on which the projection is formed is removed. A method of manufacturing a resin-encapsulated semiconductor device, comprising: forming a lower portion of a semiconductor chip while holding the semiconductor chip on a stage in which a recess is formed to avoid the already formed protrusion. 2. A projection is formed on a semiconductor chip mounting portion,
Further, when a projection is formed on a semiconductor chip, the surface on which the projection is formed is turned downward. At this time, the latter is held while holding the semiconductor chip on a stage in which a recess is formed to avoid the already formed projection. A method for manufacturing a resin-encapsulated semiconductor device, comprising: forming a projection.