JP4085639B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device having a module structure such as an IGBT (insulated gate bipolar transistor) module and a method for manufacturing the same.
[0002]
[Prior art]
As shown in FIG. 8, a power semiconductor device (semiconductor device) such as an IGBT module is usually provided on a copper wiring 65 formed on a wiring substrate 66 on a semiconductor chip 51 (hereinafter referred to as a chip) such as an IGBT chip shown in FIG. The main electrode 54 and the gate electrode 55, which are the front electrodes of the chip 51, are bonded to each other by bonding one or a plurality of aluminum wires 73 and 74 to the emitter terminal 68 and the gate. Each is connected to an external lead-out terminal which is a terminal 69. Usually, a plurality of chips 51 are housed in a package.
[0003]
[Problems to be solved by the invention]
The aluminum wire bonding has the following problems.
1) As the chip capacity increases, the number of wires required to secure the necessary current capacity increases, and the man-hours for bonding and wire bonder increase, resulting in higher costs.
2) It is structurally difficult to ensure a sufficient cross-sectional area of the copper wiring pattern on the wire 73 and the wiring board, and as a result, problems arise in heat generation of the element and response characteristics due to an increase in wiring resistance and wiring inductance. There is.
3) Even if an attempt is made to increase the diameter of the wire 73 used to reduce the number of wires 73, the bonding condition for bonding the thick wire becomes strict and the chip may be damaged, so there is a limit to increasing the thickness.
[0004]
In order to solve these problems, a structure in which copper lead frames 68 and 69 are directly bonded to the main electrode 54 and the control electrode 55 of the chip 51 as shown in FIG. ing.
However, when the lead frames 68 and 69 are connected to the main electrode of the chip as shown in FIG. 9, the lead frames 68 and 69 have a circle 74 in order to relieve the stress generated in the chip 51 by the lead frames 68 and 69. As shown in the figure, it is necessary to have a complicated structure, which increases the manufacturing cost. The reason for this complicated structure is that the lead frames 68 and 69 have flexibility.
[0005]
Also, if the copper wiring formed on the printed circuit board is joined directly to the main electrode or control electrode on the chip surface with solder or the like, the solder spreads in the lateral direction and the distance between the chip surface and the printed circuit board becomes extremely short. As a result, the electrical insulation between the main electrode formed on the chip surface and the control electrode, and the electrical insulation between the copper wiring connected to the main electrode and the control electrode and the withstand voltage structure (such as a guard ring) are reduced. .
[0006]
The object of the present invention is to solve the above-mentioned problems, at low cost, and to have good electrical insulation between the main electrode and the control electrode, and between the main electrode and the copper wiring connected to the control electrode and the pressure-resistant structure. And a method of manufacturing the same semiconductor device.
[0007]
[Means for Solving the Problems]
To achieve the above object, a main electrode and a control electrode formed on the same plane of a semiconductor chip, a breakdown voltage structure formed on the semiconductor chip, a first external lead conductor connected to the main electrode, and the control In a module-structured semiconductor device comprising a second external lead conductor connected to an electrode,
An insulating film is formed on the entire surface of the semiconductor chip and is opened on the main electrode and the control electrode, and is formed on the insulating film by being fixed to the main electrode through a fixing material at the opening of the insulating film. A first external lead conductor, and a second external lead conductor fixed to the control electrode and formed on the insulating film.
[0008]
The insulating film may be an organic insulating film.
The insulating film may have a thickness of 50 to 100 μm.
The first and second external lead conductors may be leads of a lead frame or a printed circuit board.
The fixing material may be solder or solder paste.
[0009]
In addition, a main electrode and a control electrode formed on the same plane of the semiconductor chip, a breakdown voltage structure formed in the semiconductor chip, a first external lead conductor connected to the main electrode, and a second external connected to the control electrode In a manufacturing method of a semiconductor device having a module structure comprising a lead-out conductor,
Forming a main electrode and a control electrode on a semiconductor wafer having a breakdown voltage structure and an active region; forming an insulating film having openings on the entire surface of the semiconductor wafer; a step of chips by cutting the wafer, and a main electrode and a control electrode formed on said chip semiconductor chip, a first outer lead conductor,, respectively Re its at fixing material to the second external lead conductors secured The manufacturing method including the process to do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a semiconductor device according to a first embodiment of the present invention. FIG. 1 is a plan view of a semiconductor chip, FIG. 2 is a plan view of an insulating sheet, and FIG. .
1 to 3, an insulating sheet 6 provided with openings 7 and 8 at positions located on the emitter electrode 4 and the gate electrode 5 shown in FIG. 2 is pasted on the IGBT chip 1 shown in FIG. 1. To do. Solder 9, 10 (solder paste, etc.), which is a fixing material, is attached on the emitter electrode 4 and the gate electrode 5 located in the openings 7 and 8 of the insulating sheet so as to be slightly higher than the thickness of the insulating sheet. Copper wirings 11 and 12 (corresponding to first and second external lead-out conductors) formed on the surface of the substrate 13 are fixed to the emitter electrode 4 and the gate electrode 5 via solders 9 and 10. The back surface of the IGBT chip is fixed to the copper wiring 15 formed on the surface of the wiring substrate 16 via the solder 17. The wiring board 16 and the copper base 21 (cooling conductor) are fixed with solder 17. The copper wirings 11, 12 and 15 are fixed to the emitter terminal 18, the gate terminal 19 and the collector terminal 18, and the plastic case 22 is fixed to the copper base 21. The wiring board 13 and the copper wirings 11 and 12 constitute a wiring circuit board (such as a Direct Bonding Copper board).
[0011]
The main purpose of the insulating sheet over DOO 6, since it is to ensure the electrical insulation between the guard ring 3 provided on the copper wiring 11, 12 and the IGBT chip peripheral portion is externally drawn body, while It must be able to withstand the electric field applied to the battery without long-term deterioration. Usually, the voltage during this period is several tens of volts to several kV, and therefore an insulation thickness corresponding to the rating of the element may be selected. When a polyimide resin film is used as the organic insulating film, the withstand voltage is usually about 100 kV / mm or the like, and only needs to have a thickness of about 50 μm.
[0012]
However, the actual thickness of the insulating film should be determined in consideration of the availability and workability of the film, and is practically about 50 to 100 μm. When the thickness exceeds 100 μm, the film material has poor processability and is expensive, and it is difficult to obtain a film thickness exceeding 100 μm by a coating method. Moreover, when it is less than 50 μm, there is a possibility that sufficient electrical insulation reliability cannot be obtained.
[0013]
Accordingly, the material of the insulating sheet 6 is preferably a polyimide resin sheet having a thickness of 50 μm to 100 μm, but the thickness is not limited to this. Also, the resin material is not limited to polyimide resin, and organic insulating materials such as engineering plastic resin sheets such as polyethylene terephthalate resin, polyether ether ketone resin, polyether imide resin, polysulfone resin, etc., depending on the required heat resistance temperature and dielectric strength Can be used.
[0014]
In addition, it is desirable to use an adhesive that can be heat-sealable in the process or use the heat-sealability of the sheet itself. However, a thermosetting adhesive may also be used.
The presence of the insulating sheet 6 ensures insulation between the main electrode that is the emitter electrode and the control electrode that is the gate electrode.
Further, since the insulating sheet 6 has a structure bonded directly above the guard ring portion, the copper wiring 11 fixed to the emitter electrode 4 and the guard ring 3 which is a withstand voltage structure are insulated by the insulating sheet 6. Yes.
[0015]
As described above, by sticking the insulating sheet 6 provided with the openings 7 and 8 to the surface of the IGBT chip 1, it is possible to prevent the solder 9 and 10 from spreading in the lateral direction, and the main electrode which is the emitter electrode 4. And the electrical insulation between the control electrode which is the gate electrode 5 can be ensured reliably. In addition, the insulating sheet 6 can ensure electrical insulation between the copper wirings 11 and 12 connected to the emitter electrode 4 and the gate electrode 5 and the guard ring 3 which is a withstand voltage structure.
[0016]
The dimensions of the openings 7 and 8 are for joining the main electrode and the control electrode to the external lead-out conductor, respectively, and may be any opening area corresponding to the area of the main electrode and the control electrode. Practically, the opening area is preferably 30 to 100% of the main electrode and control electrode area. In the case where the main electrode is divided into a plurality of cells, the main electrode opening may be a plurality of openings corresponding to each cell.
[0017]
In addition, the structure of the copper wirings 11 and 12 that are the external lead-out conductors can be a simple flat plate (conventionally has a complicated bent structure as shown by a circle 72 in FIG. 9).
Thus, the manufacturing cost can be reduced by simplifying the shapes of the copper wirings 11 and 12 which are the external lead-out conductors.
FIG. 4 is a cross-sectional view of the main part of the semiconductor device according to the second embodiment of the present invention. The difference from the first embodiment is not a structure in which an insulator such as an insulating sheet 6 is adhered, but a thick insulating layer 23 is formed in other portions except the emitter electrode 4 and the gate electrode 5. It is. The material of the insulating layer 23 may be any curable resin (organic insulating material) that can be patterned on the surface of the IGBT chip 1, but preferably heat resistant heat such as epoxy resin, polyimide resin, bismaleimide resin, etc. Curable resin is good.
[0018]
This pattern can be formed by screen printing, spin coating, vacuum printing, or the like.
Also, if the openings 7 of the emitter electrode 4 are not single but a plurality of openings are made for one emitter electrode 4, stress such as thermal stress applied to the joint portion with the solder 9 is relieved. can do.
[0019]
In addition, when a liquid insulating material is used in forming the insulating layer 23, when a plurality of openings are provided, the degree of freedom of the planar pattern of the openings is improved. Of course, a plurality of openings 8 of the gate electrode 5 may be formed.
According to the present invention, as in the first embodiment, the insulation between the emitter electrode 4 and the gate electrode 5 and the distance between the copper wirings 11 and 12 connected to the emitter electrode 4 and the gate electrode 5 and the guard ring 3 are low. It is possible to reliably ensure the insulation.
[0020]
FIG. 5 shows a method of manufacturing a semiconductor device according to a third embodiment of the present invention. FIGS. 5A to 5D are process cross-sectional views shown in the order of processes. This is a method of manufacturing the semiconductor device of FIG.
An insulating layer 23 in which the emitter electrode and the gate electrode are exposed is formed on the surface on the emitter electrode side of the wafer 100 on which a large number of IGBT units in which the p-type diffusion region and the n-type diffusion region are formed are integrated (FIG. 1A).
[0021]
Next, in order to obtain an IGBT chip, the wafer 100 is cut along the cutting line 24 ((b) in the figure).
Next, the openings 9 and 10 are filled with solder 9 and 10 (FIG. 3C).
Next, an emitter electrode and a gate electrode (not shown) and the copper wirings 11 and 12 formed on the wiring board 13 are fixed through solders 9 and 10. On the other hand, the back surface of the IGBT chip 1 is also fixed to the copper wiring 15 formed on the wiring board 16 via solder (not shown) ((d) in the figure).
[0022]
Next, as shown in FIG. 4, the copper base 21, the emitter terminal 18, the gate terminal 19, and the collector terminal 20 are fixed, and a plastic case 22 is covered to obtain a semiconductor device.
Thus, by forming the insulating layer 23 in a lump in the wafer state before cutting the chip, the cost for forming the insulating layer 23 can be greatly reduced. The insulating layer 23 is formed by the method described with reference to FIG. Furthermore, there is also a method in which the insulating sheet 13 shown in FIG.
[0023]
FIG. 6 is a cross-sectional view of the main part of the semiconductor device according to the fourth embodiment of the present invention. The difference from the above embodiment is that a conductor such as a lead frame is used instead of the copper wiring formed on the wiring board. FIG. 6 is a cross-sectional view of the main part corresponding to FIG. In this case, since the lead frames 24 and 25 (corresponding to the first and second outer lead-out conductors) are arranged on the insulating sheet 6, the thickness of the lead frames 24 and 25 can be made extremely thin. Therefore, a flat lead frame may be used instead of the bent complicated structure as shown in FIG. 9, and the cost can be reduced. In addition, the insulation between the main electrode and the control electrode and the insulation between the main electrode, the control electrode and the pressure-resistant structure can be ensured.
[0024]
【The invention's effect】
According to this invention, the main electrode and the control electrode are electrically connected to the external lead-out conductor through the opening of the insulating film formed on the semiconductor chip, and the external lead-out conductor is formed on the insulating film. The insulation between the main electrode and the control electrode and the insulation between the external lead conductor connected to the main electrode and the control electrode and the pressure resistant structure can be easily ensured.
[0025]
In addition, since the thin outer lead conductor is formed on the insulating film, the shape of the outer lead conductor can be simplified, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a plan view of a semiconductor chip of a semiconductor device according to a first embodiment of the present invention. FIG. 2 is a plan view of an insulating sheet of the semiconductor device according to the first embodiment of the present invention. FIG. 4 is a fragmentary cross-sectional view of a semiconductor device according to a second embodiment of the present invention. FIG. 5 is a method of manufacturing a semiconductor device according to a third embodiment of the present invention. ) To (d) are cross-sectional views of the steps shown in the order of the steps. FIG. 6 is a cross-sectional view of the main part of the semiconductor device according to the fourth embodiment of the present invention. Cross-sectional view of relevant parts [FIG. 9] Cross-sectional view of relevant parts of another conventional semiconductor device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 IGBT chip | tip 2 Active region 3 Guard ring 4 Emitter electrode 5 Gate electrode 6 Insulation sheet 7, 8 Opening 9, 10, 14, 17 Solder 11, 12, 15 Copper wiring 13, 16 Wiring board 18 Emitter terminal 19 Gate terminal 20 Collector terminal 21 Copper base 22 Plastic case 23 Insulating layers 24 and 25 Lead frame

Claims (6)

A main electrode and a control electrode formed on the same plane of the semiconductor chip, a breakdown voltage structure formed on the semiconductor chip, a first external lead conductor connected to the main electrode, and a second external lead conductor connected to the control electrode In a module-structured semiconductor device comprising:
Is the pressure-resistant structure directly above the cover there is a main electrode and a control electrode portions each opening on a semiconductor chip, and the organic insulating film is a thickness of 50 .mu.m to 100 .mu.m, the area corresponding to the area of the main electrode and the control electrode The organic insulating film has an opening, and the opening is formed on the organic insulating film by being fixed to the main electrode through a fixing material attached to the opening higher than the thickness of the organic insulating film. 1. A semiconductor device comprising: an outer lead conductor; and a second outer lead conductor fixed to the control electrode and formed on the insulating film. The semiconductor device according to claim 1, wherein the organic insulating film is a resin sheet in which the opening is formed in advance. The semiconductor device according to claim 1, wherein the organic insulating film is a curable resin capable of patterning the opening. 2. The semiconductor device according to claim 1, wherein the first and second outer lead-out conductors are leads of a lead frame or a printed circuit board. The semiconductor device according to claim 1, wherein the fixing material is solder or solder paste. A main electrode and a control electrode formed on the same plane of the semiconductor chip, a breakdown voltage structure formed on the semiconductor chip, a first external lead conductor connected to the main electrode, and a second external lead conductor connected to the control electrode In a manufacturing method of a semiconductor device having a module structure comprising:
A step of forming a main electrode and a control electrode on a semiconductor wafer on which a breakdown voltage structure and an active region are formed, and a portion where the main electrode and the control electrode are located on the semiconductor wafer and directly cover the breakdown voltage structure; Forming an organic insulating film having an area corresponding to the area of the electrode and having a thickness of 50 μm to 100 μm; cutting the semiconductor wafer into chips; and forming the chip on the semiconductor chip And a step of adhering a fixing agent to the opening on the main electrode and the control electrode which is higher than the thickness of the organic insulating film and fixing the first outer lead conductor and the second outer lead conductor with a fixing material. A method for manufacturing a semiconductor device.

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