JP2000183280A - Semiconductor element, semiconductor device and power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability of the contact resistance characteristics and temperature rise characteristics of a semiconductor element by a method, wherein a Cu base material used as a Cu layer is left at a temperature higher than its melting point in a specified low pressure to refine the element. SOLUTION: A discal semiconductor substrate 2 within an insulating container 10 is arranged between a pressure-weldable discal cathode contact 4 and a disal anode contact 5, while both surfaces of the substrate 2 are held between discal Mo heat buffer plates 3a and 3b and is brought into contact with a gate contact 7 on the side of the contact 4. The contact 4 is coupled with one end of the container 10 via a first cover 11a, and the contact 5 is coupled with the other end of the container 10 via a second cover 11b to form a semiconductor element into a structure sealed to the outside. A gate current is given to the contact 7 via a gate conductor wire connected with the outside. When a Cu base material, which is left at a temperature higher than its melting point for at least one minute in a low pressure of 10-2 Torr or lower and is controlled in the amount of oxygen and the amount of hydrogen therein, is used as a Cu layer, and pores in the Cu layer can be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element such as a pressure contact type semiconductor element, a semiconductor element having a module structure, a semiconductor device using the semiconductor element, and a power converter using the semiconductor element.

[0002]

2. Description of the Related Art Conventionally, a press-fit flat type semiconductor element and a module-structured semiconductor element are formed with at least one of constituent members such as a base, a heat sink, a post, an insert material, a thermal shock plate and an insulating substrate. Cu layer (C
u foil, a Cu film, a Cu thin plate, or a Cu plating layer).

[0003]

The above-mentioned flattened-type semiconductor device and module-structured semiconductor device are required to have improved and stable current interrupting performance as a whole semiconductor device. As a key technology that satisfies this requirement, it is required to stabilize the contact resistance characteristic and the temperature rise characteristic between each of the constituent members and the Cu layer.

However, variations in the material characteristics of the Cu layer constituting the flattened-type semiconductor device and the module-structured semiconductor device give rise to variations in the contact resistance characteristics and the temperature rise characteristics of the semiconductor device, and these characteristics become unstable. It is assumed. For example, a high oxygen content in the Cu material forming the Cu layer causes voids and pores in the Cu material, which may cause variations in the contact resistance characteristics and temperature rise characteristics of the semiconductor element. Cause.

[0005] Further, after joining each of the constituent members via the Cu layer, since the strain remaining in the Cu layer is large, "warp" is also generated in each of the constituent members, which is also a semiconductor element. This causes a problem that the contact resistance characteristics and the temperature rise characteristics of the above-mentioned devices vary.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a semiconductor device having stable contact resistance characteristics and temperature rising characteristics, a semiconductor device using this semiconductor device, and An object of the present invention is to provide a power conversion device using the semiconductor element.

[0007]

According to a first aspect of the present invention, a C contacting at least one of a plurality of components.
In a semiconductor device having a u-layer, a Cu material used as the Cu layer is manufactured by being left at a temperature not lower than its melting point at a low pressure of 10 ^-2 Torr or lower.

In another preferred embodiment of the present invention, the Cu material is allowed to stand at a temperature not lower than its melting point for at least one minute at a low pressure of 10 ^-2 Torr or less, so that the oxygen content in the Cu material is reduced. In the range of 1 to 20 ppm and the amount of hydrogen in the range of 0.1 to 5 ppm, and Bi, P
One of the components consisting of b, Te, Se, Sb, As
~ 30 ppm, and the total amount of these is 2 ~
It is controlled to 50 ppm.

According to another preferred embodiment of the present invention, a metal or alloy composition having a melting point sufficient to select a connection and integration operation temperature of 200 to 550 ° C. between each of the constituent members and the Cu layer is provided. And a Cu layer is connected and integrated by the bonding material.

Another preferred embodiment of the present invention is characterized in that the joining material is heated and held for at least 5 minutes or more at the unifying operation temperature to connect and integrate the constituent members and the Cu layer. I do.

According to another preferred embodiment of the present invention, each of the constituent members and the Cu layer are connected and integrated while cooling at an average cooling rate of 0.16 to 10 ° C./min from the heating and holding temperature. It is characterized by.

According to another preferred embodiment of the present invention, the distance between each of the constituent members and the Cu layer is 0.1 to 1000 g / m 2.
After applying the load of m ² and holding the integration work temperature for at least 5 minutes or more, 0.16 to
The above components are connected and integrated with a Cu layer while cooling at an average cooling rate of 10 ° C./min.

In another preferred embodiment of the present invention, the bonding material is 50Sn-In or 65Sn-Pb or 97Sn-Ag or 18Au-Bi or 98P.
b-1, 5Ag-Sn or 85Au-Ga or 94
AU-Si or 73Au-In.

In another preferred embodiment of the present invention, the Cu layer is an Ag layer (any one or more of an Ag foil, an Ag film, an Ag thin plate, and an Ag plating layer).

In another preferred embodiment of the present invention, the Cu material is used for any or all of a base Cu member, a heat sink Cu member, and a post Cu member which are part of the plurality of constituent members. It is characterized by having done.

According to the above-mentioned invention, in order to stabilize the contact resistance characteristics and the temperature rise characteristics, the material conditions of the Cu layer are optimized, and the conditions for suppressing the "warpage" caused by the joining of each constituent member and the Cu layer are optimized. And the technology to obtain it.

Therefore, C which is arranged in contact with each of the above-mentioned constituent members is provided.
It is necessary to optimize the material properties of the u layer and to suppress the oxygen content in the Cu material forming the Cu layer to a low value. The reason is that if the oxygen content exceeds a predetermined amount,
Vacancies and pores are formed in the u-material. If such voids and pores remain in the Cu material, it is disadvantageous for stabilizing the temperature characteristics as a semiconductor element and has an unfavorable effect on the contact resistance characteristics. is there.

That is, the amount of oxygen and the amount of hydrogen in the Cu material are suppressed within a predetermined range, and the total amount of components other than Cu which is disadvantageous for stabilization of the resistance characteristics is controlled within a predetermined range. The Cu thus manufactured is used as a Cu material for the Cu layer. Due to these synergistic effects, the contact resistance characteristics and the temperature rise characteristics of the semiconductor element are improved.

Further, in the process of manufacturing and assembling the flattened semiconductor device and the module-structured semiconductor device, a step of connecting and integrating each of the constituent members with the Cu layer to be arranged in contact therewith is carried out.
After selecting a Cu material in which the amount of oxygen and the amount of hydrogen in the Cu material are optimized as the u material content, selecting a bonding temperature that is important for maintaining a balance between the bonding strength and the magnitude of the residual strain, and achieving it. Predetermined effective temperature range (200 ~
For example, 67% Au-In alloy having a melting point of 550 ° C. and exhibiting a melting point of 500 ° C.) Selection of joining material, preferable cooling during the cooling process after joining heating, which enables reduction of stress remaining in the Cu layer and the like. By selecting a rate (0.16 to 10 ° C./min) or the like, the strain remaining in the Cu layer is reduced,
As a result, a semiconductor device without "warpage" was obtained, and the contact resistance characteristics and the temperature rise characteristics of the semiconductor device were improved.

On the other hand, C during the bonding heating process and the cooling process
A semiconductor element is manufactured and assembled by applying a load of 0.1 to 1000 g / mm ² to each of the u-layer-attached components, thereby obtaining reliable contact at the interface between each component and the Cu layer. An element with high reliability can be obtained.

Further, such excessive pressurization in the cooling process is as follows.
A seizure phenomenon was also observed between the jig and the component with the Cu layer, which was not preferable because the surface of the component with the Cu layer was damaged. As is clear from these results,
Weighted upon cooling as a range of 0.1g / mm2~1000g / mm ² is to provide a contact at the contact surfaces entirely is obtained, there was no occurrence of the "warp" upward shown a preferred temperature characteristics.

[0022] As apparent from these results, weighted upon cooling as a range of 0.1g / mm ² ~1000g / mm ² is to give, to obtain contact at the contact surfaces entirely, on showing preferred temperature characteristic No "warping" occurs.

According to another preferred embodiment of the present invention, there is provided a flat contact type semiconductor device integrated with the Cu layer in contact with each of the constituent members, or a module structure semiconductor device integrated with the Cu layer. , 200-550 ° C
A joining material composed of a metal and an alloy composition having a melting point sufficient to select the connection and integration work temperature of
It is characterized in that it is arranged between the layers and connected and integrated.

Representative examples of alloys having a melting point sufficient to select the temperature of 200 to 550 ° C. → 50Sn-In (melting point: 116 to 127 ° C.), 18Au
-Bi (melting point 241 ° C), 80Au-Sn (melting point 280)
° C), 84.6 Au-Ga (melting point 341 ° C), 88 Au
-Ge (melting point: 356 ° C.), 75 Au-Sb (melting point: 360 °)
C), 94Au-Si (melting point 370C), 73.3 Au
—In (melting point: 451 ° C.) is preferred.

Also, 100Sn, 96.5Sn-Ag
(Melting point 221 ° C.), 95Sn—Sb (melting point 235 to 24)
0 ° C), 97.5Pb-Ag (melting point 304 ° C),
5Pb-1.5Ag-Sn (melting point 309 ° C), 10Sn
-Pb (melting point 268-301 ° C), 5Sn-Pb (melting point 300-314 ° C), 2Sn-Pb (melting point 316-32)
2 ° C.) is also preferred.

Further, 95Zn-Al (melting point: 382 ° C.) is also preferable.

In a preferred embodiment of the present invention, each of the constituent materials (base, heat sink, post,
Cu layer (Cu foil, Cu) placed in contact with one or more of the insert material, hot street hitting board, and green board
Film, a Cu thin plate, or a Cu plating layer), the Cu material used for each of the Cu layers is 10
^-2 Torr at a low pressure of not more than 1 minute at a temperature not lower than its melting point, so that the oxygen content in the Cu material is 1-20 ppm and the hydrogen content is 0.1-5 ppm.
And Bi, Pb, Te, Se, S
A Cu material produced by controlling one of the components consisting of b and As to a range of 1 to 30 ppm and controlling the total amount thereof to 2 to 50 ppm is used as the Cu layer.

Another preferred embodiment of the present invention is characterized in that the plurality of semiconductor elements are housed in the same package.

Another preferred embodiment of the present invention is characterized in that power conversion is performed using the above-mentioned semiconductor device.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the semiconductor device of the present invention. The semiconductor element 1 is formed of a disc-shaped laminate that can be pressed into the inside of a ring-shaped insulating container 10, and has a semiconductor substrate 2 at the center.

Disc-shaped semiconductor substrate 2 in insulating container 10
Has a disk shape on both sides, for example, a heat buffer plate 3a made of Mo,
While being sandwiched by 3b, it is arranged between a press-contactable disc-shaped cathode contact 4 and a press-contactable disc-shaped anode contact 5, and is connected to the gate contact 7 on the cathode contact side. The cathode contact 4
Is connected to one end of the insulating container 10 via a first cover 11a, and the anode contact 5 is connected to the other end of the insulating container 10 via a second cover 11b to be sealed from the outside. It has a structured structure. A gate current is applied to the gate contact 7 via a gate conductor 8 connected to the outside.

The heat accumulated in the semiconductor substrate 2 is M
o It is discharged to the outside through the thermal buffer plates 3a and 3b, or through the cathode contact 4 and the anode contact 5. Cooling means such as cooling fins may be individually added.

The flattened semiconductor device 1 as described above is composed of a snubber circuit composed of a snubber diode and a snubber capacitor, and a conductor connecting these components to each other, and is used, for example, in a power converter.

Since the effect of the present invention due to the use of a sound Cu layer is exhibited irrespective of a flat-plate type semiconductor device and a module-structured semiconductor device, a flat-plate type semiconductor device will be described here as a representative example.

Here, the basic concept of the present embodiment will be described. Generally, when two solids are brought into contact, the contact is not made over the entire contact area, but is actually made at the true contact area in which minute contact points are accumulated. Usually, the true contact area is smaller. The basis is the value of the true contact area between the opposing surfaces. With a given semiconductor substrate, there is a limit to the power and temperature (rise) that can be tolerated. One of the measures to improve the contact properties of a semiconductor element is to realize a uniform current distribution and good heat dissipation. Is a major issue.

According to the analysis by the inventors, the amount of gas and specific components in the Cu layer were particularly suppressed to optimize the Cu layer. As a result, it is possible to suppress the contact thermal resistance between the Cu layer and the constituent members by suppressing defects such as vacancies in the Cu layer itself to make the material sounder.

Further, by adding auxiliary technologies such as selection of a connection work temperature at the time of connection integration of each constituent member and the Cu layer, selection of a corresponding bonding material, and control of a cooling rate in a cooling process, a Cu layer is formed. Suppressing the "warpage" generated in the attached component also contributes to the improvement of the contact resistance characteristic and the temperature rise characteristic of the semiconductor element.

Bi, Pb, Te, and the like in the Cu material used for each Cu layer, which are particularly likely to inhibit the joining function,
1 to 30 ppm of one of the components consisting of Se, Sb and As
And the Cu material manufactured by controlling the total amount thereof to 2 to 50 ppm was used as the Cu layer, so that it has an effect of reducing the generation of vacancies in the Cu layer and has a structure. The interface between the member and the Cu layer obtains a perfect contact state. As a result, excellent contact resistance characteristics and temperature characteristics can be obtained.

Further, by leaving the material at a temperature not lower than its melting point for at least 1 minute at a low pressure of 10 ^-2 Torr or less, the oxygen content in the Cu material can be reduced to 1-20 ppm and the hydrogen content can be reduced to 0.1-5 ppm. Since the Cu material manufactured so as to be controlled in the range was used as the Cu layer, similarly,
The generation of vacancies in the u layer can be reduced. As a result, excellent contact resistance characteristics and temperature characteristics can be obtained.

Next, C constituting the semiconductor device shown in FIG.
An outline of an evaluation apparatus when optimizing the material condition of the u layer and optimizing the condition for suppressing the warpage due to the joining between each constituent member and the Cu layer will be described.

One surface of a semiconductor substrate 2 provided with a silicon wafer having a diameter of 150 mm (radius of 75 mm) has a heat buffer plate 3a having a thickness of 0.7 mm, and the other surface has a thickness of 0.7 mm.
mm heat buffer plate 3a,
An evaluation device was prepared in which the respective components were arranged in the order of the semiconductor substrate 2 and the Mo thermal buffer plate 3b.

Next, a thickness of 10 mm
A Cu post (cathode contact 4, anode contact 5) having an outer diameter of 170 mm (radius 85 mm) and a surface roughness of, for example, 2 μm is installed, and one post (cathode contact 4) is connected to the heat buffer plate 3a. So that the other post (anode contact 5) contacts the thermal buffer plate 3b in the order of the cathode contact 4, the thermal buffer plate 3a, the semiconductor substrate 2, the thermal buffer plate 3b, and the anode contact 5. Each member was arranged.

In some embodiments described below, one of the heat sinks and the other heat sink is in contact with the heat buffer plate 3b so that one heat sink contacts the heat buffer plate 3a. Each member was arranged in the order of the heat buffer plate 3a, the semiconductor substrate 2, the heat buffer plate 3b, and the other heat sink.

Conditions for evaluating the characteristics In order to evaluate the temperature characteristics, these were supported in a column (not shown), then placed in an experimental vessel, a load of 60 kg / cm ² was applied to the whole, and a power of 6 kV and 6 kA was applied. After shutting off,
In a state where the load is removed, that is, a cycle of [load application → power cutoff → load removal] is repeated once and five times,
Values including the ambient temperature were used as temperature characteristics.

At this time, when the temperature value of the third embodiment before the power of 6 kV and 6 kA was cut off was set to 1.0, the temperature value after the cutoff of 1 to 5 times was relatively compared. The temperature measurement position was one point at the center and the outer periphery of each component member surface. Since the temperature characteristics reflect the contact resistance characteristics and the contact heat resistance characteristics, in this example, the basic characteristics of the entire device can be comprehensively determined by evaluating the temperature characteristics.

For the evaluation of the contact resistance characteristics, the above-mentioned temperature characteristics were evaluated after arranging predetermined components in the above-described evaluation device. The contact resistance value of Example 3 was set at 1.0 before the power of 6 kV and 6 kA was cut off, and the contact resistance values after the cutoff of 1 to 5 times were relatively compared. Measurement is DC 24V, 100m
A was given and measured. In addition, for integration of each constituent member and the Cu layer, a joining material having a predetermined melting point was arranged and joined between them.

The table of FIG. 2 listing the evaluation conditions of the Cu material of the Cu layer of the semiconductor device shown in FIG. 1 and the temperature characteristics and contact characteristics of the semiconductor device using the Cu material for each of the above evaluation conditions Will be described with reference to the table of FIG.

Examples 1-3, (Comparative Example 1) Condition (a) of Comparative Example 1: vacuum degree 6 × 10 ⁻¹ Torr, condition (b) of Example 1: 1 × 10 ⁻² Torr, Example Condition 2 (c): 5 × 10 ⁻³ Torr; Condition (d) of Example 3: 2 × 10 ⁻⁴ Torr in an atmosphere of at least one minute while heating and holding at or above its melting point. A Cu material was manufactured.

As a result of examining the gas content in the Cu material thus manufactured, oxygen was 75 ppm and hydrogen was 12 ppm under the condition (a), but the conditions (b), (c) and
In (d), they were 15 to 20 ppm and 1 to 5 ppm, respectively.

Similarly, specific elements Bi, Pb,
As a result of investigating the total amount of Te, Se, Sb, and As, 125 ppm was obtained under the condition (a), and the conditions (b), (c), and (d) were obtained.
Was 30 to 50 ppm.

In the case of the condition (a), the evaporation loss of these specific elements during the production was small due to the low degree of vacuum. The reason for making these specific elements is that Bi in the Cu layer,
Pb, Te, Se, Sb, and As are connected to the Cu layer and the constituent members by a predetermined amount (50 pp) in connecting and integrating the constituent members.
If it is larger than m), the bonding strength is significantly reduced. Furthermore,
When these elements are present in a predetermined amount or more, the amount of vacancies and pores in the Cu layer increases. Accordingly, the total gas content in the Cu material is 2 to 50 ppm, and the specific element amount is 2 to 50 ppm.
50 ppm.

In the metallographic examination conducted as part of the quality evaluation of the Cu material, pores were present inside the material under condition (a), but the conditions (b), (c) and (d) Was not recognized. Further, the material was not preferable as an element material, for example, a material blistering phenomenon occurred when heated at 800 ° C. in hydrogen. However, the material blistering phenomenon did not occur under the conditions (b), (c) and (d).

As a result of examining the gas content, under the condition (a), oxygen was 75 ppm and hydrogen was 12 ppm.
In the conditions (b), (c) and (d), each is 20 to 15 pp
m, 5 to 1 ppm. These conditions (a),
The Cu material manufactured in (b), (c), and (d) was used as a raw material for the elemental Cu layer.

These Cu layers are arranged on one surface of a heat buffer plate (constituent member) made of Mo, and 30 mm is provided between the heat buffer plate and the Cu layer.
g / mm ² , and 80% by weight A
After heating and holding at a temperature of 300 ° C. for 10 minutes using u-Sn, a semiconductor device was manufactured by integrating at a cooling rate of 1.66 ° C./min (Examples 1 to 3 and Comparative Example 1).

As a result, assuming that the temperature characteristic of the third embodiment before the power of 6 kV and 6 kA was cut off was 1.0, the temperature characteristics of 6 kV and 6 kA were not changed.
After the power of kA is cut off, the load is removed, that is,
When comparing the temperature characteristics after one cycle of [load application → power cutoff → load removal], the condition (b),
(C) and (d) are in the range of 1.0 to 1.1, and the temperature characteristics after repeating the above evaluation cycle five times are also 1.
The range was from 02 to 1.13, all of which were at a low level, and the range of fluctuation was small and within an allowable range.

On the other hand, before the power of 6 kV and 6 kA was cut off, the temperature characteristic of the third embodiment was set to 1.0, and the power of 6 kV and 6 kA was cut off under the condition (a). When the temperature characteristics after one cycle of the removed state, ie, [load application → power cutoff → load removal] cycle, are 1.08 to 1.30, the temperature characteristic after five cycles is also 1 .11 to 1.37, and the fluctuation range increased with the level of the value, which was out of the allowable range.

Observation of the cross-sectional structure after completion of the evaluation shows that, in the case of the Cu layer made of the Cu material manufactured under the condition (a), a portion where the interface between the constituent member and the Cu layer is not completely adhered is obtained. , And minute voids were also observed. The poor adhesion is considered to be due to poor wettability due to the formation of a film on the contact surface by the gas.
This is considered to be due to pores due to the release of gas from the layer portion. Under the conditions (b), (c) and (d), such a phenomenon is not observed.

On the other hand, an effect was also observed in the contact resistance characteristics. That is, before the power of 6 kV and 6 kA is cut off, assuming that the temperature characteristic of the third embodiment is 100 and the power of 6 kV and 6 kA is cut off, the load is removed under the conditions (b), (c) and (d). The contact resistance after performing one cycle of [load application → power interruption → removal of load] is in the range of 108 to 127, and the contact resistance after repeating the above evaluation cycle 5 times is compared. The values are also 110-13
6, all of which were at a low level, and the fluctuation range was small and within an acceptable range.

On the other hand, assuming that the temperature characteristic of the third embodiment is 100 before the power of 6 kV and 6 kA is cut off, the power of 6 kV and 6 kA is cut off and the load is removed, that is, [load application]. → Electric power cut → Remove load]
Comparing the temperature characteristics after one cycle, the conditions (a) indicate 126 to 188, and the temperature characteristics after five cycles also indicate 131 to 263. Have also increased and are out of tolerance.

Observation of the cross-sectional structure after completion of the evaluation shows that, in the case of the Cu layer made of the Cu material manufactured under the condition (a), a portion where complete adhesion was not obtained at a part of the interface between the constituent member and the Cu layer. , And minute voids were also observed. The poor adhesion is considered to be due to poor wettability due to the formation of a film on the contact surface by the gas.
This is considered to be due to pores due to the release of gas from the layer portion. Under the conditions (b), (c) and (d), such a phenomenon is not observed.

Observation of the surface state of the Cu layer after completion of the evaluation revealed that the surface of the Cu layer made of the Cu material manufactured under the condition (a) showed a slight discoloration on a part of the surface and fine irregularities. . Light discoloration is considered to be mainly due to oxidation by oxygen gas released from the Cu layer itself in the heating process of contact integration of the component and Cu layer, and minute irregularities are due to gas release traces and loads during measurement cycle. It is thought to be due to the collapse of the internal micropores.

Examples 4 to 11 (Comparative Examples 2 to 4) In Examples 1 to 3 and Comparative Example 1, the integration of the component and the Cu layer during the contact integration of the component and the Cu layer was performed. 80% Au—Sn having a melting point of 280 ° C. as a joining material
The semiconductor element was assembled using an alloy at a joining operation temperature of 300 ° C., but the present embodiment is not limited to the 80% Au—Sn alloy, but the invention effect of the Cu layer on the improvement of the contact resistance characteristics and the temperature characteristics. Demonstrate.

The composition of the bonding material of Comparative Example 2 was 50 Bi-
31Pb-Sn (melting point 95 ° C, joining work temperature 115 ° C)
It is.

The compositions of the joining materials of Examples 4 to 11 are 50 Sn-In (melting point: 116 to 127 ° C., joining temperature: 150 ° C.) and 65 Sn-Pb (melting point: 183 to 185, respectively).
° C, joining operation temperature 200 ° C), 97Sn-Ag (melting point 2
21C, bonding work temperature 240C), 18Au-Bi (melting point 241C, bonding work temperature 260C), 98Pb-1,
5Ag-Sn (melting point 309 ° C, joining temperature 330
° C), 85 Au-Ga (melting point 341 ° C, joining work temperature 3
60 AU), 94 AU-Si (melting point 370 ° C, joining temperature 390 ° C), and 73 Au-In (melting point 451 ° C, joining temperature 550 ° C).

The compositions of the bonding materials of Comparative Examples 3 and 4 were 45 Ag-35Cu-In (melting point: 600 ° C., bonding temperature: 650 ° C.), 78Cu-5 and 7Ni-7P-S, respectively.
n (melting point 700 ° C., joining temperature 750 ° C.). A semiconductor device was assembled using the bonding material having the above composition.

Also in this example, the same methods as in Examples 1 to 3 and Comparative Example 1 were evaluated, and all showed acceptable temperature characteristics and contact resistance characteristics. However, in the case of 50 Bi-31Pb-Sn of Comparative Example 2, the state of contact integration between the constituent member and the Cu layer after the joining step is not sufficient, and the contact resistance characteristics vary, and the joint strength is sufficient. Is not obtained, due to the action of low pulling force and slight vibration,
Phenomena such as a state of easily peeling off from the contact interface and falling off occurred, and thus, it was not a preferable semiconductor element.

On the other hand, 45Ag-3 shown in Comparative Examples 3 and 4
In the case of 5Cu-In, 78Cu-5 and 7Ni-7P-Sn, the state of contact and integration between the component and the Cu layer after the bonding step was sufficient, and sufficient tensile strength was obtained, but the contact resistance after cooling was low. A phenomenon was observed in which the overall resistance of the material varied and the resistance level also increased. The occurrence of “warpage” was confirmed in the entire joint due to an increase in residual thermal stress and the like.

This is an example in which even if the material conditions of the Cu layer are properly selected, if the working temperature of the contact integration is not favorable, the characteristics of the whole semiconductor element are adversely affected.

Accordingly, the selection of a Cu layer made of an appropriate Cu material and the selection of a bonding material capable of selecting the working temperature for contact integration of the constituent member and the Cu layer in the range of 200 ° C. to 550 ° C. A combination with selection was required, and in Examples 4 to 11, good results were obtained in both contact resistance characteristics and temperature characteristics.

In addition to the above-mentioned bonding materials, for example,
00Sn, 95Sn-Sb (melting point 235 ° C to 240
C), 97.5 Pb-Ag (melting point 304 C), 97.5
Pb-11 and 5Ag-Sn (melting point 309 ° C), 10Sn-
Pb (melting point 268-301 ° C), 5Sn-Pb (melting point 3
00-314 ° C), 2Sn-Pb (melting point 316-322)
° C), 95Zn-Al (melting point: 382 ° C) and the like are also suitable.

Here, when a bonding temperature of 550 ° C. or more is selected, residual stress exists inside each constituent member, the Cu layer, and the like, and “warping” occurs in the semiconductor element after cooling.
For example, 77.6% Cu-5.7 having a melting point of about 700 ° C.
% Ni-7P-Sn was used to perform the bonding heat treatment at 750 ° C., but stable contact resistance characteristics and temperature rise characteristics were not obtained due to the occurrence of “warpage”, and the semiconductor device was not a preferable semiconductor device. Was. 45% with a melting point of about 600 ° C
Bonding heat treatment was performed at 650 ° C. using Ag-35% Cu—In, but stable contact resistance characteristics and temperature rise characteristics could not be obtained, so that a preferable semiconductor element was not obtained.

As described above, in the press-fit flat semiconductor device connected and integrated with the Cu layer in contact with each of the constituent members, or in the module-structured semiconductor device connected and integrated with the Cu layer, the predetermined condition of the present example is satisfied. After selecting the Cu layer, a metal having a melting point sufficient to select a connection and integration operation temperature of 200 to 550 ° C., and a bonding material made of an alloy composition are arranged between each constituent member and the Cu layer, It has been found that the integration of the connection is beneficial for the production of a semiconductor device having stable contact resistance characteristics and temperature rising characteristics.

Embodiments 12 to 14 In the above embodiments 4 to 11, the semiconductor device was assembled with the holding time at the joining operation temperature at the time of contact and integration of the constituent member and the Cu layer being 10 minutes. The invention effect of the Cu layer on the improvement of the contact resistance characteristics and the temperature characteristics is exhibited without limitation.

The evaluation of this example (Examples 12 to 14) was carried out in the same manner as in the above Examples and Comparative Examples.
The contact resistance characteristics were shown.

Examples 15 to 16 (Comparative Examples 5 and 6) In Examples 1 to 14, the cooling rate after maintaining the joining temperature at the time of contact integration of the constituent member and the Cu layer for 10 minutes was 1. Although the semiconductor element was assembled at 66 ° C./min, the cooling rate of the present invention is not limited to 1.66 ° C./min, and the effect of the Cu layer on the improvement of contact resistance characteristics and temperature characteristics is exhibited.

In the present embodiment (Examples 15 and 16), evaluation was performed in the same manner as in the above Examples and Comparative Examples.
By the synergistic action with the selection of ° C./min, the strain remaining in the Cu layer is reduced, and as a result, a semiconductor device without “warpage” is obtained, and the contact resistance characteristics and the temperature rise characteristics of the semiconductor device are improved. I was able to.

However, in Comparative Example 5 (0.05 to 0.1 ° C./min or less) in which the cooling rate was excessively slow, there was no problem with the contact resistance characteristics and the temperature rise characteristics of the semiconductor element.
Unfavorable for productivity. In Comparative Example 6 (2000 ° C./min) in which the cooling rate was excessively high, “warpage” occurred, the contact resistance characteristics and the temperature rise characteristics deteriorated, and the following problems were observed: Are excluded from the present invention.

Examples 17 to 19 (Comparative Examples 7 and 8) In Examples 1 to 16 and Comparative Examples 1 to 6, the components and C
The magnitude of the load applied at the time of contact integration with the u layer is 30 g /
Although the semiconductor element was assembled in mm ² , the cooling rate of this example is not limited to 30 g / mm ² , and the invention effect of the Cu layer on the improvement of the contact resistance characteristics and the temperature characteristics is exhibited.

This example was evaluated in the same manner as in the above examples and comparative examples.
All of ° C./min (Examples 17 to 19) showed acceptable temperature characteristics and contact resistance characteristics.

However, the cooling rate of Comparative Example 7 was 0.1 g /
If it is less than ² mm ² , “warpage” occurs, and
If the surface roughness is 000 g / mm ² , the surface roughness due to baking has an unfavorable effect on the contact resistance characteristics and the temperature characteristics of the semiconductor element, and is excluded from the present invention.

That is, C during the bonding heating process and the cooling process
The load applied to each of the constituent members with the u layer is 0.1 g / mm ²
In the case where the element was manufactured by integrating the component and the Cu layer as described below, occurrence of remarkable “warpage” was observed in the component with the Cu layer.

Also, due to the occurrence of "warpage", when the semiconductor element is assembled and assembled, a non-contact portion is observed microscopically, and the contact characteristics and the temperature characteristics are unstable.

That point: 0.1 g / mm ^{2 to} 1000 g / m
As m ² , the semiconductor element in the case of manufacturing the component members obtains reliable contact at the interface between each component and the Cu layer,
An element with higher reliability can be obtained without occurrence of “warpage”. After manufacturing under these conditions, when disassembling and pressing the surface under a microscope, it is recognized that microscopic contact points are distributed over almost the entire surface by selecting an appropriate cooling rate.

With such excessive pressurization during the cooling process (2000 g / mm ^{2 in} Comparative Example 8), contact at the contact point locally preferentially progresses in the microscopic portion where the contact point was first formed. It can be seen that a small area that is not touching around the contact point is generated.

As a result, the presence of microscopically uniform residual strain and the generation of minute surface roughness on the surface of the component with a Cu layer to which an excessive load has been applied, particularly in the evaluation cycle described above. As the number of times increases, the occurrence of variation in resistance characteristics tends to become remarkable, which is not preferable.

As is apparent from these results, after selecting the Cu layer under the predetermined conditions of the present embodiment (Examples 17 to 19), the applied load was 0.1 g / mm ^{2 to} 1000 g /
By contacting the entire surface of the contact surface by cooling and connecting and integrating it within the range of mm ² , it shows favorable temperature characteristics, no warpage, stable contact resistance characteristics and stable temperature rise characteristics. It has been found that the method is useful for manufacturing a semiconductor device having the same.

Examples 20 to 25 In Examples 1 to 19 and Comparative Examples 1 to 8, a thermal shock plate was selected as a constituent member, a plate shape was selected as a form of a Cu layer, and the plate thickness was 30 to 200 μm. And the semiconductor element is assembled, but the present embodiment is not limited to this and can be applied. Even with other constituent members, other Cu layer forms and layer thicknesses, a Cu layer obtained from a predetermined Cu material effectively exerts an effect, and a semiconductor element having stable contact resistance characteristics and temperature rising characteristics. Can be manufactured.

In Examples 20 to 24, E was applied to one side of the base.
A Cu film having a thickness of 3 to 30 μm by the B method, a thin Cu plate having a thickness of 0.1 to 1 mm on one surface of the heat sink, and a Cu film having a thickness of 3 to 30 μm by a plating method on one surface of the post
A semiconductor element having a Cu film having a thickness of 3 to 30 μm and a Cu foil having a thickness of 0.2 to 3 mm for an insert material was prepared on one surface of the layer and the insulating substrate (AlN) by a sputtering method in argon.

The Cu layer, the CuCu film, and the Cu foil effectively exerted their effects, and a semiconductor device having stable contact resistance characteristics and temperature rising characteristics could be manufactured. Also, as in the twenty-fifth embodiment, the same effect as described above can be obtained by using Ag instead of Cu in the Cu layer.

The evaluation results in Table 2 show the results of Examples 1 to 19 described above.
In the above, the values are shown as relative values with the value of Example 3 being 1.0.
In Examples 20 to 25, immediately after assembling each component as a semiconductor device for evaluation (before current interruption).
Was set to 1.0.

Other Examples In Examples 1 to 25 and Comparative Examples 1 to 8, the constituent members and Cu were used.
In the connection integration with the layer (Ag layer), Cu
The effect of the Cu layer (Ag layer) manufactured using the material (Ag material) has been described.
The present invention is effective not only for layers, plates, and foils, but also for uses of constituent members themselves.

For example, the condition (a): degree of vacuum 6 × 10 ^-1 Torr and the condition (d): degree of vacuum 2 × Assembling a semiconductor device using the Cu material manufactured in an atmosphere of 10 ^-4 Torr,
The invention effect was compared.

According to this, the component using the Cu material under the former condition (a) has a temperature rise characteristic of 1.15 to 1.15.
In addition to showing a 1.3 times higher (poor) value, the contact resistance characteristics also showed a 1.2-3.9 times high (poor) value.

[0094] Therefore, the Cu material has been confirmed to have the effect of the invention in addition to the Cu layer used integrally with the constituent members described above.

As described above, any one or all of the Cu member for the base, the Cu member for the heat sink, and the Cu member for the post forming the press-fit flat type semiconductor element, the module structure semiconductor element, and the semiconductor element using the Cu material are manufactured. By manufacturing, the stability of the contact resistance characteristic and the temperature rise characteristic of the semiconductor element can be improved.

[0096]

As described above in detail, according to the semiconductor device of the present invention, the optimization of the material conditions of the Cu layer and the optimization of the conditions for suppressing the warpage caused by the joining of the respective constituent members and the Cu layer are achieved. In addition, the stability of the member contact resistance characteristic and the temperature rise characteristic can be improved.

According to the semiconductor device of the present invention, it is possible to improve the stability of the member contact resistance characteristic and the temperature rise characteristic.

According to the power converter of the present invention, it is possible to improve the stability of the contact resistance characteristic and the temperature rise characteristic of the member, and to improve the reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor device of the present invention.

FIG. 2 is a table listing evaluation conditions of Examples and Comparative Examples of the present invention.

FIG. 3 is a table listing characteristics of a semiconductor element manufactured using a Cu material under the evaluation conditions of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Semiconductor substrate 3a, 3b Mo disk 4 Cathode contact 5 Anode contact 6 Insulated passive part 7 Gate contact 8 Gate conductor 10 Insulated container 11a First cover 11b Second cover

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Kusano 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (72) Inventor Atsushi Yamamoto 1-Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba ( 72) Inventor Takanori Nishimura 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Fuchu Plant, Toshiba Corporation (72) Inventor Kenji 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Fuchu Plant, Toshiba Corporation (72) Inventor Yutaka Ishiwatari Kanagawa 2-4-4 Suehirocho, Tsurumi-ku, Yokohama-shi In the Toshiba Keihin Works Co., Ltd. (72) Inventor Akira Tanaka 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Toshiba Keihin Works 5F036 AA01 BB01 BC08 BD01 BE06

Claims (11)

[Claims] 1. A semiconductor device comprising a Cu layer in contact with at least one of a plurality of constituent members, wherein a Cu material used as the Cu layer has a melting point or higher at a low pressure of 10 ⁻² Torr or lower. A semiconductor device characterized by being manufactured by being left at a temperature. 2. The oxygen content in the Cu material is reduced to 1 to 2 by leaving the Cu material at a temperature equal to or higher than its melting point for at least 1 minute at a low pressure of 10 ⁻² Torr or less.
0 ppm and the amount of hydrogen are controlled in the range of 0.1 to 5 ppm, and one of the components consisting of Bi, Pb, Te, Se, Sb and As is suppressed in the range of 1 to 30 ppm, and the total amount of these components is 2 to 30 ppm. 2. The semiconductor device according to claim 1, wherein the semiconductor device is controlled to 50 ppm. 3. Between each of the constituent members and the Cu layer, 20
A joining material made of a metal or alloy composition having a melting point sufficient to select a connection / integration operation temperature of 0 to 550 ° C. is arranged, and the constituent members and the Cu layer are connected and integrated with the joining material. 3. The semiconductor device according to claim 1, wherein: 4. Heating and holding the bonding material at the integration work temperature for at least 5 minutes or more, and
4. The semiconductor device according to claim 3, wherein the semiconductor device is integrated with a u layer. 5. The heating and holding temperature is 0.16 to 10 ° C.
The semiconductor device according to claim 3, wherein each of the constituent members and the Cu layer are connected and integrated while cooling at an average cooling rate of / min. 6. A 0.1 mm gap between each of the constituent members and the Cu layer.
After applying the load of 1 to 1000 g / mm ² and maintaining the integration work temperature for at least 5 minutes or more, the above-mentioned constituent members are cooled at an average cooling rate of 0.16 to 10 ° C./minute from the holding temperature. 5. The semiconductor device according to claim 3, wherein a Cu layer and a Cu layer are connected and integrated. 7. The bonding material is 50Sn-In or
65Sn-Pb or 97Sn-Ag or 18Au-
Bi or 98Pb-1, 5Ag-Sn or 85Au
7. The semiconductor device according to claim 3, wherein the semiconductor device is any one of -Ga, 94AU-Si, and 73Au-In. 8. The semiconductor device according to claim 1, wherein said Cu layer is an Ag layer. 9. The Cu material is used for any or all of a Cu member for a base, a Cu member for a heat sink, and a Cu member for a post, which are a part of the plurality of constituent members. 8. The semiconductor device according to any one of claims 7 to 7. 10. A semiconductor device comprising a plurality of semiconductor elements according to claim 1 housed in the same package. 11. A power converter using the semiconductor device according to claim 1 for power conversion.