JP2000068298A - Manufacture of semiconductor element and power converter incorporating semiconductor element manufactured thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing semiconductor element, by which the contacting efficiencies between heat impingement plates and post electrodes can be improved and a power converter incorporating the semiconductor element manufactured using the method. SOLUTION: An MoCu material is manufactured by applying a load of 0.1-1,000 gr/mm2 to at least one surface of the material and a semiconductor element 1 is manufactured by using the MoCu material for heat impinging plates 3a and 3b. Therefore, the contacting efficiencies between the plate 3a and a cathode contact (post electrode) 4 and between the plate 3b and an anode contact (post electrode) 5 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device using a MoCu material or the like, and a power converter incorporating the semiconductor device manufactured by the method.

[0002]

2. Description of the Related Art An ordinary semiconductor device comprises a semiconductor substrate (silicon wafer), an electrode in contact with the substrate, a heat buffer plate made of Mo in contact with the electrode, and a pressure contact between these components. A pair of external electrodes (post electrodes)
And consists of

[0003] As described above, the respective members are brought into contact with each other by the pressing force of the pair of external electrodes.
It is important to suppress the contact thermal resistance generated at the contact interface between the semiconductor substrate and the heat buffer plate and the contact interface between the heat buffer plate and the external electrode.

This will be described with reference to FIG. 1. Generally, in a semiconductor device, only the functions as electrodes and heat sinks are provided on the heat buffer plates 3a and 3b in order to suppress power consumption and heat generation per unit area. In addition, high mechanical strength is required to obtain particularly uniform contact with the semiconductor substrate surface, uniform current distribution, and high heat dissipation.

For this reason, conventionally, in assembling the semiconductor device 1, as a technique for maintaining the cooling capability of the device and eliminating the cause of device destruction due to temperature rise, heat is led out to the cooling fins or the heat buffer plate 3a. And 3b are placed in close contact with each other while applying a predetermined high pressure to the surface of the semiconductor substrate 2 to increase the efficiency of heat extraction. As the heat buffer plates 3a and 3b, generally, disk-shaped Mo plates, W plates, and the like having high mechanical strength are frequently used.

[0006]

In recent years, the semiconductor element 1 has been required to have a higher breakdown voltage and a larger current.
In order to increase the capacity of the semiconductor element 1 such as GTO, IGBT, etc., it is necessary to increase the diameter of the semiconductor substrate 2. In particular, when the current is increased, for example, the element area, that is, the area of the semiconductor substrate 2 is adjusted, and therefore, the uniformity of the gas flow in the element surface is an important issue. In the case where the current is non-uniform, there is a case where the device breaks down due to current concentration at the time of turn-off.

Here, when Mo is used as the thermal buffer plates 3a and 3b as described above, since it has a large mechanical strength, a certain amount of pressing force is applied to the semiconductor substrate 2.
It is possible to give to the surface.

Further, in order to alleviate the problem of contact resistance, a metal such as Ni is plated on the surface of the Mo thermal buffer plate. With these techniques, the non-uniformity of the current in the element surface is reduced.

However, the specific resistance value and contact resistance value of Mo itself are not sufficiently low, and the hardness is relatively large. At present, contact has not been sufficiently obtained.

Therefore, it may not always be satisfactory to obtain a more uniform current distribution and higher heat dissipation. Therefore, it is inevitable to increase the contact area by applying a larger pressing force to the semiconductor element 1.

As a result, there is a limit in suppressing the temperature rise of the semiconductor element 1, and there are inconveniences such as an obstacle to miniaturization of the semiconductor element 1. That is, in the contact portion between the cathode contact (post electrode) 4 and the Mo thermal buffer plate 3a and the contact portion between the Mo thermal buffer plate 3b and the anode contact (post electrode) 5, the contact state (contact resistance, thermal resistance) From the point of view of), some phenomena are not enough.

Therefore, from the viewpoint of improving the above-mentioned contact state, instead of Mo, Cu / M is obtained by superposing Mo and Cu.
o, a Cu / Mo / Cu composite or a MoCu alloy is used, and thermal buffer plates 3a and 3b suitable for improving contact resistance and thermal resistance are provided.

However, such Mo / Cu, Cu / Mo
It is essential for Mo / Cu composites and MoCu alloys to keep a sufficient contact state between Mo and Cu in order to improve contact resistance and thermal resistance.

Therefore, in the manufacturing process, diffusion contact or diffusion bonding by heating may be performed in order to obtain strong adhesion. In such bonding by heating, the MoCu material may be deformed, such as "warp", due to the difference in thermal expansion between the two metals. As a result, a portion of the contact interface is not sufficiently contacted when viewed microscopically, and problems (contact resistance, heat resistance) are pointed out from the viewpoint of reliability and productivity.

The present invention has been made in view of the above circumstances, and particularly relates to a method of manufacturing a semiconductor device in which the contact efficiency between a thermal buffer plate and a post electrode is improved, and a method of assembling a semiconductor device manufactured by the method. It is an object of the present invention to provide an embedded power converter. The contact efficiency mentioned here takes into account not only the contact resistance between the opposing members but also the heat transfer from one of the two members to the other.

[0016]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention provides a method of manufacturing a semiconductor device according to the present invention, in which Mo / Cu, Cu / Mo / Cu composite,
In the production of a material such as a Cu alloy, a method of producing a suitable material having no deformation such as "warp" in the composite, alloy, or the like, and developing a semiconductor element using the material is developed.

That is, the present invention is characterized in that a MoCu material is manufactured while applying a load of 0.1 to 1000 gr / mm ² to at least one surface of the MoCu material, and a semiconductor element is manufactured using the MoCu material. Is a method of manufacturing a semiconductor device.

Further, the present invention provides an average cooling in a cooling process from a holding temperature during heat treatment to 200 ° C. while applying a load of 0.1 to 1000 gr / mm ² to at least one surface of the MoCu material. Speed 0.16 ~ 10 ℃
/ Minute, a MoCu material is manufactured, and a semiconductor device is manufactured using the MoCu material.

Further, the present invention manufactures a MoCu material by setting a cooling rate in a cooling process from a holding temperature during the heat treatment of the MoCu material to 200 ° C. in a cooling process of 0.16 to 10 ° C./min. A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device using the method.

Further, according to the present invention, after the MoCu material is once manufactured by heat treatment, the MoCu material is kept at a temperature of 200 to 1000 ° C. for at least 5 minutes, and is applied to at least one surface of the MoCu material at 0.1 to 1000 gr / Mo by performing a reheating treatment of cooling while applying a load of mm ²
A method for manufacturing a semiconductor device, comprising manufacturing a Cu material and manufacturing a semiconductor device using the MoCu material.

Further, according to the present invention, after the MoCu material is once manufactured by heat treatment, the MoCu material is kept at a temperature of 200 to 1000 ° C. for at least 5 minutes, and at least one surface of the MoCu material is 0.1 to 1000 gr / While applying a load of ² mm2, a reheating treatment was performed by cooling at an average cooling rate of 0.16 to 10 ° C / min from the holding temperature to 150 ° C to produce a MoCu material.
A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device using a u material.

Here, when manufacturing a semiconductor device using the MoCu material, the semiconductor substrate placed in the insulating container is placed between the cathode contact and the anode contact while the both surfaces thereof are sandwiched between the thermal buffer plates. The cathode contact is connected to the gate contact on the cathode contact side, the cathode contact is connected to one end of the insulating container via the first cover, and the anode contact is connected to the other end of the insulating container via the second cover. It is also possible to use a MoCu material as a buffer plate of a semiconductor element that is connected and sealed to the outside and that receives a gate signal at a gate contact.

In the case of manufacturing a semiconductor device using a MoCu material, a plurality of semiconductor substrates sandwiched between a pair of heat buffer plates made of a MoCu material are installed in one package to manufacture the semiconductor device. It may be.

Further, WMoCu obtained by substituting Mo for a part or all of Mo in the MoCu material with W
It may be a material or a WCu material. Furthermore, MoCu
Material, WMoCu material, or WCu material
Material, WMoCu material, or MoCuAg material in which part or all of Cu in the WCu material is replaced with Ag,
oAg material, WMoCuAg material, WMoAg material, W
It may be a CuAg material or a WAg material.

Furthermore, MoCu material, WMoCu material, WCu material, MoCuAg material, MoAg material, WCu material
MoCuAg material, WMoAg material, WCuAg material,
Or Cu amount, Ag amount, or CuAg in WAg material
The amount may account for 0.5% to 50% by volume.

Further, a power converter can be constructed by incorporating the semiconductor elements manufactured by these manufacturing methods. Here, the operation of the method for manufacturing a semiconductor device according to the present invention will be described.

Generally, when two solids are brought into contact with each other, 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 allowable power and temperature (rise), so one of the measures for improving the contact property as a semiconductor element is to provide a uniform current distribution and good heat dissipation. Realization is a major problem, and according to the analysis of the inventors, it is particularly preferable to suppress the contact thermal resistance between the Mo thermal buffer slope and the Cu post electrode to be low.

On the other hand, the function of Mo in the conventional heat buffer plate is as follows.
Since Mo has sufficient mechanical properties (strength), it is useful to transmit an external force to the entire surface of the semiconductor substrate, but this sufficient mechanical property conversely reduces the above-mentioned true contact area. Direction, which is not always advantageous from that point of view.

Further, in a semiconductor element, if the state of equilibrium with cooling is broken and a temperature rise is caused, the element may be destroyed. Mo
Is not necessarily advantageous from the viewpoint of heat dissipation (semiconductor substrate / Mo thermal buffer plate / post electrode / cooling fin) from its thermal characteristics (thermal conductivity).

From these considerations, as a measure for solving the problem,
This suggests that it is advantageous to replace Mo of the Mo thermal buffer plate with a member having both mechanical properties and thermal properties to some extent.

As a heat buffer plate that satisfies this requirement, Mo, such as a MoCu composite or a MoCu alloy, whose heat dissipation is improved by Cu while maintaining its mechanical properties by Mo.
Cu material is mentioned as a useful means. But,
Due to the heat treatment given when manufacturing the MoCu material, "warp" occurs in the MoCu material such as the composite or alloy. This is caused by a remarkable difference in the coefficient of thermal expansion between Mo and Cu. The presence of the "warp" significantly reduces the value of the true contact area between the opposing surfaces. Generally, this will impair the contact between the electrodes.

Therefore, a method for manufacturing a semiconductor device according to the present invention comprises:
In the production of a MoCu material made of a MoCu composite, a MoCu alloy, or the like, in order to ensure reliable contact, optimization of production conditions free of the occurrence of “warpage” has been achieved.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings. A semiconductor device such as a GTO or an IGBT manufactured according to an embodiment of the present invention constitutes a power converter by using, for example, a snubber circuit including a snubber diode and a snubber capacitor and a conductor connecting these components. can do.

FIG. 1 is a sectional view of a semiconductor device manufactured according to an embodiment of the present invention. In FIG. 1, a semiconductor element 1 is formed of a disc-shaped laminate that can be pressed into a ring-shaped insulating container 10, and has a semiconductor substrate 2 at the center. This semiconductor substrate 2 has an M
It is in contact with thermal buffer plates 3a and 3b made of oCu material.

That is, the semiconductor element 1 is placed in the insulating container 1.
The disc-shaped semiconductor substrate 2 disposed at 0 is sandwiched between the disc-shaped MoCu thermal buffer plates 3a and 3b,
The gate contact 7 is disposed between the press-contactable disc-shaped cathode contact 4 and the press-contactable disc-shaped anode contact 5, and is disposed on the cathode contact 4 side.
And the cathode contact 4 is connected via the first cover 11a
The anode contact 5 is connected to one end of the insulating container 10, and the anode contact 5 is connected to the other end of the insulating container 10 via the second cover 11 b to be sealed from the outside. The gate contact 7 is connected to the outside. A gate current is applied via the gate conductor 8 thus formed, and the semiconductor device can be cut off.

The heat stored in the semiconductor substrate 2 is MoC
The heat is discharged to the outside through the heat buffer plates 3a and 3b made of u and / or the cathode contact 4 and the anode contact 5. Cooling means such as cooling fins may be individually added.

Although the semiconductor substrate 2 shown in FIG. 1 is a single disk-shaped semiconductor substrate, for example, as shown in FIG.
_a, 2 _b, FIG. (b) shows as three fan-panel-shaped semiconductor substrate 2 _A, 2 _B, 2 _C or drawing four square plate-shaped semiconductor substrate as shown in (c) 2 _1, , 2 ₂ , 2 ₃ , 2 ₄
May be arranged, and the plurality of semiconductor substrates may be sandwiched between the thermal buffer plates 3a and 3b so as to be installed in one package.

In this embodiment, the heat buffer plate 3a,
The MoCu material used as 3b is manufactured under the manufacturing conditions as in the following example, and the semiconductor element 1 is manufactured using the manufactured MoCu material. Here, first,
A method for evaluating a MoCu material manufactured in the following examples will be described.

(Evaluation method) The diameter was 150 mm (radius 7
5 mm) so that one surface of the semiconductor substrate 2 provided with a silicon wafer is sandwiched between a heat buffer plate 3a with a thickness of 0.7 mm and the other surface with a heat buffer plate 3b with a thickness of 0.7 mm. Each member was arranged in the order of plate 3a / semiconductor substrate 2 / thermal buffer plate 3b. In this embodiment, the heat buffer plate 3a particularly uses a MoCu material having a predetermined composition range.

Next, the thickness is 10 mm and the outer diameter is 170 m.
m (radius: 85 mm) and a post electrode (pure Cu post and MoCu post electrodes, ie, a cathode contact 4, an anode contact 5) whose surface roughness is finished to, for example, 2 μm, is prepared.
Cathode contact 4 / heat buffer 3a / semiconductor so that one post electrode (cathode contact) 4 contacts heat buffer 3a and the other post electrode (anode contact) 5 contacts heat buffer 3b. Each member may be arranged in the order of substrate 2 / thermal buffer plate 3b / anode contact 5.

In some implementations, one heat sink / heat buffer plate 3a / semiconductor substrate 2 / so that one heat sink contacts heat buffer plate 3a and the other heat sink contacts heat buffer plate 3b. Each member may be arranged in the order of the heat buffer plate 3b / the other heat sink.

The evaluation of the temperature characteristics was carried out by supporting these with a column (not shown), and then installing them in an experimental vessel, and measuring the total temperature for 60 k.
g / cm ² and the power of 6 kV and 6 kA was cut off, and then the load was removed, that is, when the number of repetitions of the “load application → power cutoff → load removal” cycle was one, and 30 At this time, the temperature characteristics including the ambient temperature were compared and evaluated (FIGS. 5 and 6).

Since the temperature characteristics reflect the contact resistance characteristics and the contact heat resistance characteristics, in this embodiment, the basic characteristics of the entire device were determined by evaluating the temperature characteristics. The temperature measurement position is 4 mm inside from the surface of the cathode contact 4 having a thickness of 10 mm, and the sum of one point at the center of the cathode contact disk and the outer periphery (six points on a concentric circle having a radius of 60 mm: at intervals of 60 degrees). 7 points were given. The same applies to the temperature measurement of the heat sink.

(Examples 1 to 4, Comparative Examples 1 and 2) Examples 1 to 4 and Comparative Examples 1 and 2 evaluated by changing the load applied to the MoCu material during the manufacturing process will be described (FIGS. 3 and 4). 5).

10% Cu-M with Cu content of 10% by volume
Prepare a heat buffer plate made of o. In this case, 10% Cu-
The cooling rate from the holding temperature of the heat treatment during the manufacturing process of the Mo thermal buffer plate to 150 ° C. is constant at 1.66 ° C./min, and a load of 0.1 to 2000 gr / mm ² is manufactured. The MoCu material is cooled by a method of cooling while giving to the 10% Cu-Mo in the process (FIG. 3, condition (a): applying a load to the MoCu material in the manufacturing process. The same applies to Examples 5 to 8 described later). It was manufactured (Examples 1 to 4, Comparative Example 2).

The holding temperature of the heat treatment is limited to 1000 ° C. when the conductive component in the heat buffer plate is Cu (9 ° C. for Ag).
If the temperature is equal to or higher than these temperatures, the evaporation loss of Cu or Ag is remarkable and is excluded. In addition, even if a temperature of 200 ° C. or less was selected as the holding temperature, “warpage” was not suppressed, so that it was excluded.

From these, the heat treatment during the manufacturing process of the 10% Cu—Mo thermal buffer plate was performed at a holding temperature of 1000 ° C.
(900 ° C. for Ag) to 200 ° C.

After mixing as a base member of the heat buffer plate to form a molded body, a predetermined ratio of Cu to Mo (10% by volume) is obtained by a sintering method, a hot press method or an arc melt method.
(Cu-Mo). After 10% Cu-Mo, MoC was formed by hot forging and hot / cold rolling.
u material.

If necessary, after bonding a Cu plate (100% Cu) to one surface of the MoCu material, the MoCu material having a surface Cu layer was again formed by hot / cold rolling.
Also, if necessary, both can be MoCu by a thermal diffusion method.
Cu in the material and Cu in the surface Cu layer were continuously integrated.

Further, a Mo skeleton whose porosity is adjusted,
Alternatively, Cu is infiltrated into the voids of Mo containing a small amount of Cu to form M
An oCu material may be manufactured. By leaving the remaining part of the infiltrant Cu used in the manufacturing on the surface of the MoCu material, the surface Cu layer continuously integrates Cu inside the MoCu material and Cu in the surface Cu layer from the beginning. You may get the material.

Alternatively, after a Cu plate (100% Cu) is adhered to one surface of the Cu-Mo alloy, a hot / cold rolling method is used to form a surface Cu layer, and Cu inside the MoCu material and Cu in the surface Cu layer are combined. A material that is continuously integrated may be used (MoCu, WCu, and Mo-WCu materials are the same).

Further, Mo and Cu (for example, in a plate shape) are superposed, and the two are integrated mechanically or metallurgically.
An oCu composite or, if necessary, a brazing material placed between the two, and a fusion or diffusion of the brazing material to join and integrate the MoCu composite or a MoCu composite in which one surface of Mo is coated with Cu (for example, thermal spraying). It may be used as a material for the body.

In Examples 1-4 and Comparative Examples 1-2, a post electrode was cut out from a 100% Cu block and used. The heat buffer plate (MoCu material) manufactured according to the method of the present invention manufactured through the above-mentioned predetermined cooling rate and the Cu post electrode opposed thereto are brought into close contact with each other by a silver brazing method or a thermal diffusion method, and are subjected to mechanical pressure. The method of closely contacting and opposing was appropriately selected and adopted.

[0055] Specific methods of temperature measurement, after decomposing apart arrangement of each member, except the weight of 60 kg / cm ^2, the task of providing a load of 60 kg / cm ² Assembly each member again, measurement performed once This operation was repeated 30 times and the same temperature was measured at the end.

That is, a comparison was made between the temperature characteristics when the number of repetitions of the [load application → power interruption → load removal] cycle was one and thirty. As a result, 10% by volume Cu-M
When the MoCu material (standard Mo plate (Comparative Example 1)) is manufactured with the weight given to o being less than the conventional condition of less than 0.1 gr / mm ² , the center is 7 when the number of repetitions is one.
At 2 ° C., the outer periphery was 70 to 75 ° C. (the range of the upper and lower limits at the time of six-point measurement), and when the number of repetitions was 30, the center was 92 ° C. and the outer periphery was 85 to 105 ° C. (Comparative Example 1). In this case, remarkable "warpage" occurred in the MoCu material. In Comparative Example 1, the occurrence of “sludge”
When assembled as a semiconductor element, microscopically non-contact portions are observed. Also, comparing the number of repetitions of the [load application → power cutoff → removal of load] cycle between 1 and 30, the increase in surface damage is more severe at 30 times.

On the other hand, the weight given is 0.1 gr /
When the MoCu material was manufactured under the condition of mm ^{2 to} 1000 gr / mm ^2, as a result of comparing the temperature characteristics when the number of repetitions of the “load application → power interruption → removal of load” cycle was 1 and 30 times, the number of repetitions was 1 The number of repetitions is 65 to 52 ° C., the outer portion is 64 to 50 ° C., and the number of repetitions is 30, the center is 66 to 54 ° C. and the outer portion is 6
7 to 52 [deg.] C., all of which were within a preferable range. In this case, the MoCu material not only secured a preferable temperature range, but also did not generate "warp" in the MoCu material (Examples 1 to 4).

After manufacturing the MoCu material, Examples 1-4
When the MoCu material is decomposed and subjected to microscopic observation of the pressurized surface, it is recognized that microscopic contact points are distributed over almost the entire surface by selecting an appropriate cooling rate.

However, when the MoCu material was manufactured with the applied load of 2000 / mm ² , the results of comparing the temperature characteristics when the number of repetitions of the [load application → power cutoff → load removal] cycle was one and thirty were compared. When the number of repetitions is 1, the central portion is in the range of 60 ° C. and the outer portion is in the range of 62 to 68 ° C., and when the number of repetitions is 30, the central portion is 67 ° C. and the outer portion is in the range of 66 to 81 ° C. Is 1
In the case where the number of repetitions was 30, the temperature characteristics tended to have remarkable variation, which was not preferable. In addition, due to excessive pressurization during the cooling process, a seizure phenomenon was observed between the jig and the MoCu material, and the surface of the MoCu material was damaged, which was not preferable (Comparative Example 2).

As apparent from these results, the applied weight was less than 0.1 gr / mm ² (standard Mo plate, Comparative Example 1).
0.1 gr / mm
^When cooled in the range of ^{2 to} 1000 gr / mm ² , contact was obtained on the entire contact surface, and a MoCu material showing favorable temperature characteristics and free from warpage was obtained (Examples 1 to 4). .

(Examples 5 to 8, Comparative Examples 3 and 4) In Examples 1 to 4 and Comparative Examples 1 and 2, the cooling rate during the manufacturing process of the 10% Cu-Mo thermal buffer plate was set to 1. The effect of the load applied to the MoCu material at a constant temperature of 66 ° C./min has been described. However, the cooling rate applied to the MoCu material in the method of the present invention is not limited to 1.66 ° C./min, and the effect is exhibited. I do.

Examples 5 to 8 and Comparative Examples 3 and 4 evaluated by changing the cooling rate applied to the MoCu material during the manufacturing process will be described (see FIGS. 3 and 5). That is, the cooling rate given to the MoCu material during the manufacturing process is 0.16-1.
When the MoCu material is manufactured in the range of 0 ° C./minute, the MoCu material can be manufactured without warping or deformation.
When the selected cooling rate is in the range of 0.16 to 10 ° C./min, the applied load is 30 gr / mm ² and the MoC
When u material is manufactured, the above-mentioned [load application → power cutoff →
Load removal] The number of cycles is 1 and 30
As a result of the comparison of the temperature characteristics, when the number of repetitions is 1, the central portion is in the range of 53 to 67 ° C., and the outer peripheral portion is in the range of 51 to 66 ° C. When the number of repetitions is 30, the central portion is 56 to 68.
° C and the outer peripheral portion showed 52 to 68 ° C, all of which were within the preferred range.

In this case, the MoCu material not only secured a preferable temperature range and exhibited stable temperature characteristics, but also did not generate "warp" in the MoCu material (Examples 5 to 8).

After manufacturing the MoCu material, Examples 5 to 8
When the MoCu material is decomposed and subjected to microscopic observation of the pressurized surface, it is recognized that microscopic contact points are distributed over almost the entire surface by selecting an appropriate cooling rate.

When the cooling rate applied to the MoCu material during the manufacturing process is 0.16 to 3 ° C./min (Examples 5 to 7), as shown in FIG.
Each time, the temperature is in the range of 51 to 57 ° C, while 10 ° C /
(Example 8) shows a temperature of 64-68 ° C., which is slightly higher than the above. However, since the MoCu material can be manufactured without any warpage or deformation, the allowable range was set (Example 8). ).

The cooling rate given to the MoCu material shown in Comparative Example 3 was 0.05 to 0.1 ° C./min, and the cycle of [load application → power cutoff → load removal] cycle was one and one. As far as the temperature characteristics at the time of 30 times were compared, the temperature characteristics were in a preferable value range,
According to the microscopic observation and microscopic analysis of the surface of the MoCu material after the heat treatment, the elongation of the heat treatment time causes the selective evaporation loss due to the difference in vapor pressure between Cu and Mo to be accumulated,
The surface of the MoCu material may have microscopic irregularities, and the prolonged heat treatment time is extremely disadvantageous to industrial economy and lacks realism. Therefore, it was excluded from the conditions of the present invention (Comparative Example 3). .

On the other hand, at the cooling rate of 30 ° C./min applied to the MoCu material shown in Comparative Example 4, the temperature characteristics were compared when the number of repetitions of the “load application → power cutoff → load removal” cycle was 1 and 30. As a result, when the number of repetitions is 1, the central part is in the range of 77 ° C., the outer peripheral part is in the range of 67 to 79 ° C.,
When the number of repetitions is 30, the central portion shows 94 ° C and the outer peripheral portion shows 87 to 97 ° C.
Regardless of the number of times, the temperature characteristics were unfavorable, and the temperature characteristics tended to show remarkable variations. Furthermore, the effect of correcting "warpage" was not obtained, which was not preferable (Comparative Example 4).

As is apparent from the results, when the cooling rate applied to the MoCu material during the manufacturing process is in the range of 0.16 to 10 ° C./min, the expected effect of preventing “warpage” of the MoCu material is preferable. It is possible to obtain a MoCu material having temperature characteristics and having reliability and economy.

(Examples 9 to 13 and Comparative Examples 5 to 6) In Examples 1 to 8 and Comparative Examples 1 to 4, as a method of manufacturing the MoCu material, a predetermined load was applied to the MoCu material during the manufacturing process. While cooling at a predetermined cooling rate,
Although the method using the u material has been described, the present invention is not limited to this, and as another method for obtaining the MoCu material,
The effect is also exerted by a method in which the MoCu material is heated again after it has been manufactured (after it has been once cooled) and then subjected to a reheating treatment of cooling while applying a predetermined load to the MoCu material ( 3 and 5).

That is, while applying a reheating treatment and applying a predetermined load (FIG. 3, (b): applying a load at the time of reheating treatment of the MoCu material after the manufacturing process), the cooling rate is set to 0.1.
When the temperature was set to the range of 16 to 10 ° C./min, as a result of comparing the temperature characteristics when the number of repetitions of the [load application → power interruption → removal of load] cycle was 1 and 30 times, when the number of repetitions was 1 Is 52-65 ° C and the outer periphery is 51-
In the range of 63 ° C. and the number of repetitions is 30, the center is 5
The temperature was 6 to 67 ° C., and the outer peripheral portion was 52 to 66 ° C., all of which were in the preferable values.

In this case, the MoCu material not only secured a preferable temperature range and exhibited stable temperature characteristics, but also did not generate warpage in the MoCu material (Examples 9 to 13).

For the MoCu materials of Examples 9 to 13,
After decomposing after the above-mentioned 30 temperature characteristic evaluations, microscopic observation of the pressurized surface revealed that microscopic contact points were distributed over almost the entire surface and "warpage" was not observed by selecting an appropriate cooling rate.

In the reheating treatment, the cooling rate applied to the MoCu material is in the range of 0.16 to 3 ° C./min (Examples 9 to 10).
In (12), as shown in FIG. 5, the temperature characteristic is in the range of 51 to 56 ° C. for one and 30 repetitions.
While the variation is small and extremely stable, 10
C / min (Example 13) shows 63-67 ° C, which is slightly higher than the above. However, since the MoCu material can be manufactured without any warpage or deformation, it was set to an allowable range. Example 13).

In the reheating treatment shown in Comparative Example 5, M
The cooling rate given to the oCu material is 0.05 to 0.1 ° C /
Min, and as long as the temperature characteristics when the number of repetitions of the [load application → power cutoff → removal of load] cycle was set to 1 and 30 were compared, the temperature characteristics were in a preferable value range. According to the microscopic observation and microscopic analysis of the surface of the MoCu material, the elongation of the heat treatment time causes the selective evaporation loss due to the difference in vapor pressure between Cu and Mo to accumulate. In some cases, microscopic irregularities having the same tendency as in Example 3 can be seen, and prolonged heat treatment time is extremely disadvantageous to industrial economics and is fatal to reality, and is therefore excluded from the preferred conditions of the present invention. (Comparative Example 5).

On the other hand, during the reheating treatment shown in Comparative Example 6, M
At a cooling rate of 30 ° C./min to be applied to the oCu material, the temperature characteristics of the cycle of [load application → power cutoff → load removal] cycle were once and 30 times. 75 ° C, the outer circumference is 65-7
In the range of 6 ° C. and 30 repetitions, the center was 92
° C, the outer peripheral portion shows 85 to 96 ° C, so that regardless of the number of repetitions, 30 times, unfavorable temperature characteristics,
The temperature characteristics tended to show remarkable variations. Furthermore, the expected effect of correcting the "warpage" was not obtained, which was not preferable (Comparative Example 6).

The processing temperature in the reheating treatment applied to the MoCu material is in the range of 200 to 1000 ° C. (900 ° C. for Ag). Here, if a temperature of 1000 ° C. (900 ° C. for Ag) or more is selected, C
The thermal selective evaporation of u or Ag is significantly large,
If the temperature is lower than ℃, the expected effect of correcting the "warpage" cannot be obtained.

Further, it is not economically advantageous to control the cooling to a temperature lower than 150 ° C. On the other hand, the holding time is preferably 5 minutes or more. If the time is less than 5 minutes, the expected effect of correcting the "warpage" cannot be obtained, which is not preferable.

As is evident from the results, when the cooling rate given to the MoCu material in the reheating treatment is in the range of 0.16 to 10 ° C./min, the expected effect of the “warp” correction on the MoCu material is preferable. It is possible to obtain a MoCu material having temperature characteristics and having reliability and economy.

As is apparent from the results, in Examples 1 to 13, the preferred range for the MoCu material during the manufacturing process or during the reheating treatment after the manufacturing was compared to the 10% Cu-Mo shown in Comparative Example 1. The synergistic effect of controlling the load on the substrate and controlling the cooling rate in a preferable range for the MoCu material during the manufacturing process or during the reheating treatment after the manufacturing was exhibited (see FIGS. 3 and 5).

(Examples 14 to 18, Comparative Examples 7 to 8) In Examples 1 to 13, 10% Cu-Mo was used as the heat buffer plate.
For the purpose of the present invention, it is possible to control the load of the MoCu material in the preferred range during the manufacturing process or at the time of the reheating treatment after the production and to control the M during the manufacturing process or the reheating treatment after the production.
(a synergistic effect with controlling the cooling rate in a preferable range for the oCu material), the effect of the present invention is as follows.
Not only for the thermal buffer plate made of 0% Cu-Mo, but also for (0.
5 to 50)% Cu is also effective for the remaining Mo (Examples 14 to 18) (see FIGS. 4 and 6).

That is, 10% Cu-M
Instead of o, 0.5% Cu remaining Mo, 1.5% Cu remaining Mo, 5% Cu remaining Mo, 15% Cu remaining Mo, 50
The same evaluation as described above was carried out for the MoCu material using the% Cu residual Mo.

As a result of comparing the temperature characteristics when the number of repetitions of the [load application → power interruption → removal of load] cycle is 1 and 30, the center is 51 to 66 ° C. and the outer periphery is In the range of 50 to 66 ° C. and the number of repetitions is 30, the center is 53 to 67 ° C. and the outer periphery is 5
2 to 69 ° C., all of which were within the preferable range. In this case, the MoCu material secured a preferable temperature range, exhibited stable temperature characteristics, and did not generate "warp" (Examples 14 to 18).

For each of the MoCu materials of Examples 14 to 18, after the temperature characteristic evaluation was performed 30 times, the MoCu material was disassembled and subjected to microscopic observation of the pressurized surface.
Microscopic contact points were distributed over almost the entire surface, and no "warpage" was observed.

On the other hand, 10% Cu
-The same evaluation as described above was performed on Mo materials using 100% Mo instead of Mo. [Load application →
Power cut-off → Remove load] 1 cycle
As a result of comparing the temperature characteristics of the cycle and the cycle of 30 times, when the number of repetitions is 1, the central portion is in the range of 78 ° C. and the outer portion is in the range of 76 to 79 ° C. Was 90 to 101 ° C., which was not preferable because of a high temperature rise and a variation in temperature value (Comparative Example 7). Thus, the Mo material exhibited an unfavorable temperature value and unstable temperature characteristics (Comparative Example 7). That is, Examples 1 to 1 described above were used.
In No. 8, the effect due to the presence of a predetermined range of Cu in the heat buffer plate is exhibited. However, in the Mo material (Comparative Example 7), the contact resistance and the contact heat resistance are not preferable, and Demonstrated temperature values and unstable temperature characteristics.

On the other hand, the same evaluation as described above was carried out on a MoCu material using 65% Cu-Mo instead of 10% Cu-Mo as a heat buffer plate. [Load application →
Power cut-off → Remove load] 1 cycle
As a result of comparing the temperature characteristics of the cycle and the cycle of 30 times, when the number of repetitions is 1, the central portion is 50 ° C. and the outer peripheral portion is in a range of 50 to 51 ° C., and when the number of repetitions is 30, the central portion is 52 ° C. Although the temperature characteristics were in the range of extremely good values as far as the temperature characteristics were compared, the temperature characteristics were in an extremely good range, but according to the microscopic observation and microscopic analysis of the MoCu material surface after the heat treatment, In some cases, large irregularities were observed, and the contact resistance values also varied (Comparative Example 8).

(Examples 19 to 21) Examples 1 to 13
In the above, Mo was selected as a material for supporting the strength as a heat buffer plate, and the effect of the present invention was shown. However, the effect of the present invention is exhibited without being limited thereto (Examples 19 to 2).
1) (see FIGS. 4 and 6).

That is, 10% Cu-M
10% Cu balance W, 10% Cu balance W-
Mo, WCu, WMo using remaining 10% AgCu W
The same evaluation as described above was performed for Cu and WAgCu materials.

As a result of comparing the temperature characteristics when the number of repetitions of the load application → power cutoff → removal of the cycle is 1 and 30 times, when the number of repetitions is 1, the center is 51 to 53 ° C. and the outer periphery is In the range of 50 to 53 ° C. and the number of repetitions is 30, the center is 53 to 55 ° C. and the outer periphery is 5
1 to 54 ° C., all of which were within the preferable range. As described above, the WCu, WMoCu, and WAgCu materials ensured a preferable temperature range, exhibited stable temperature characteristics, and did not generate "warp".

After the evaluation of the temperature characteristics for 30 times, the sample was decomposed and subjected to microscopic observation of the pressurized surface. On the surface, microscopic contact points were distributed over almost the entire surface, and "warpage" was not observed. 10% Cu-Mo (Examples 1 to 13)
(Examples 19 to 21).

(Examples 22 and 23) Examples 1 and 2
1. In Comparative Examples 1 to 8, MoCu, WCu, WM either during the manufacturing process or during the reheating process after the manufacturing.
Although a predetermined load is applied to the oCu and WAgCu materials, the present invention is not limited to this.

[0091] The MoCu and WCu materials in the manufacturing process were obtained by the ordinary general manufacturing method without applying the load.
oCu, WCu material is subjected to a reheating process, even when a predetermined load is applied during this reheating process and cooled, the same as when the load is applied to the MoCu and WCu material during the manufacturing process. (See the comparison between Example 22 and Example 3), but MoCu and WCu during the manufacturing process are obtained.
After the MoCu or WCu material is manufactured by applying a predetermined load to the material, the material may be subjected to a reheating process while further applying an equivalent load ((a) + (b) in FIG. After a load is applied to the MoCu material to obtain the MoCu material, a load is applied during reheating and cooling of the MoCu material after this manufacturing process), and the effect is exerted (Example 23) (see FIGS. 4 and 6).

In the above Examples 1 to 23, instead of 10% Cu-Mo, 10% Cu remaining W, 10% Cu remaining W-Mo, and 10% AgCu remaining W were used instead of 10% Cu-Mo.
Were evaluated for the WCu, WMoCu, and WAgCu materials using, but a heat buffer plate composed of these materials may be provided with a Cu layer as a surface layer. That is, as the material of the surface Cu layer of the heat buffer plate, 100% Cu, Cu-
0.2 Ag, Cu-7.5 Ag, Cu-28 Ag, Cu
-92.5Ag, Cu-0.1Ni, Cu-0.1S
n, Cu-0.15Zr, Cu-0.8Cr,
As a result of obtaining the same temperature characteristics, when the number of repetitions of the [load application → power interruption → removal of load] cycle is one, the central portion is in the range of 57 to 61 ° C. and the outer peripheral portion is in the range of 58 to 64 ° C. Even if the number of times is 30, the center is 59-6
The temperature was 4 ° C., and the outer peripheral portion was in the range of 55 to 65 ° C., and preferred temperature characteristics were exhibited. In each case, the conductivity was 80% IACS or more, and the Vickers hardness was in the range of Hv = 30 to 80 or less.

Further, the thickness of the surface Cu layer of the heat buffer plate is set to 0.
When the temperature was set to 1 to 30 μm, the same temperature characteristics were obtained. As a result, when the number of repetitions of the [load application → power interruption → load removal] cycle was one, the center was 55 ° C. and the outer periphery was 53 to 55 ° C. Even if the number of repetitions is 30 times, the central portion is in the range of 57 to 59 ° C. and the outer peripheral portion is in the range of 53 to 57 ° C., and favorable temperature characteristics are exhibited.

Further, the thickness of the surface Cu layer of the heat buffer plate was
As a result of obtaining the same temperature characteristics as described above in the range of 0.1 to 100 μm, when the number of repetitions of the [load application → power cutoff → load removal] cycle is one, the central portion is 66 points.
° C, the outer peripheral portion is in the range of 64 to 66 ° C. Even if the number of repetitions is 30, the central portion is 69 ° C, and the outer peripheral portion is 67 to 69 ° C.
° C, exhibiting favorable temperature characteristics.

In the case where the heat buffer plate and the heat sink are brought into contact with each other and Cu in them is continuously integrated,
As a result of obtaining the same temperature characteristics, when the number of repetitions of the [load application → power interruption → removal of load] cycle is one, the central portion is in the range of 56 ° C. and the outer peripheral portion is in the range of 54 to 59 ° C. 30 times, the central portion is in the range of 60 ° C., and the outer peripheral portion is in the range of 56 to 61 ° C., exhibiting favorable temperature characteristics.

(Examples 24-26) Examples 1-2
3. In Comparative Examples 1 to 8, Examples and Comparative Examples in which Cu (AgCu in Example 21) was used as the conductive component in the thermal buffer plate were shown, but in the present invention, a part or all of Cu was used. It is needless to say that the same effect can be exerted even if is replaced with Ag (Examples 24 to 26) (see FIGS. 4 and 6). In addition,
In the above description, the effects of the present invention have been shown mainly for flat elements, but it is needless to say that the present invention can be applied to semiconductor elements other than flat elements, and the same effects can be exerted.

[0097]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the temperature characteristics of the material of the heat buffer plate are made favorable, so that the temperature characteristics of the entire semiconductor device can be improved. . Therefore, the present invention contributes to the improvement of the reliability of the semiconductor device manufactured by the manufacturing method of the present invention and the power converter incorporating the semiconductor device.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing the arrangement of another example of a semiconductor substrate in a semiconductor device manufactured according to an embodiment of the present invention.

FIG. 3 is a table showing manufacturing conditions and material configurations in Examples 1 to 13 and Comparative Examples 1 to 6 of the present invention.

FIG. 4 shows Examples 14 to 26 of the present invention and Comparative Examples 7 to 8.
FIG. 2 is a table showing manufacturing conditions and material configurations in FIG.

FIG. 5 is a table showing evaluation results in Examples 1 to 13 and Comparative Examples 1 to 6 of the present invention.

FIG. 6 shows Examples 14 to 26 of the present invention and Comparative Examples 7 to 8.
FIG. 9 is a table showing evaluation results in FIG.

[Explanation of symbols]

1 ... semiconductor element _{2,2 a, 2 b, 2 A} , 2 B, 2 C, 2 1, 2 2, 2 3, 2 4
... Semiconductor substrate 3a, 3b ... Heat buffer plate 4 ... Cathode contact (post electrode) 5 ... Anode contact (post electrode) 6 ... Insulated passive part 7 ... Gate contact 8 ... Gate conductor 10 ... Insulated container 11a ... First cover 11b ... 2nd cover

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kusano 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Toshiba Fuchu Plant, Inc. 72) Inventor Atsushi Yamamoto 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba Corporation (72) Inventor Hiroshi Ishiwatari 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Keihin Plant (72) Inventor Atsushi Kimoto 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Toshiba Keihin Works Co., Ltd. 5F047 JA08 JC00

Claims (11)

[Claims] 1. At least one surface of a MoCu material,
Mo while applying a load of 0.1 to 1000 gr / mm ²
A method of manufacturing a semiconductor device, comprising manufacturing a Cu material and manufacturing a semiconductor device using the MoCu material. 2. The method according to claim 2, wherein at least one surface of the MoCu material has
While applying a load of 0.1 to 1000 gr / mm ² , the average cooling rate in the cooling process from the holding temperature during the heat treatment to 200 ° C. was set to 0.16 to 10 ° C./min.
A method of manufacturing a semiconductor device, comprising manufacturing a Cu material and manufacturing a semiconductor device using the MoCu material. 3. The cooling rate in the cooling step from the holding temperature during the heat treatment of the MoCu material to 200.degree.
A MoCu material was manufactured at 16 to 10 ° C./min.
A method for manufacturing a semiconductor device, comprising manufacturing a semiconductor device using an oCu material. 4. After the MoCu material is once manufactured by heat treatment, the MoCu material is kept at a temperature of 200 to 1000 ° C. for at least 5 minutes, and the MoCu material is formed on at least one surface of the MoCu material.
0.1～1000Gr / while applying a load of mm ² to produce a MoCu material by reheating process is performed for cooling, a method of manufacturing a semiconductor device characterized by manufacturing a semiconductor device by using the MoCu material. 5. Once the MoCu material has been manufactured by heat treatment, it is kept at a temperature of 200 to 1000 ° C. for at least 5 minutes, and at least one surface of the MoCu material is
While applying a load of 0.1 to 1000 gr / mm ² , the average cooling rate from the holding temperature to 150 ° C. is set to 0.1.
A method for manufacturing a semiconductor device, comprising manufacturing a MoCu material by performing a reheating treatment at a cooling rate of 16 to 10 ° C./min, and manufacturing a semiconductor device using the MoCu material. 6. When manufacturing a semiconductor device using a MoCu material, a semiconductor substrate disposed in an insulating container is disposed between a cathode contact and an anode contact while both surfaces thereof are sandwiched between thermal buffer plates. The cathode contact is connected to a gate contact on the cathode contact side, the cathode contact is connected to one end of the insulating container via a first cover, and the anode contact is connected to the other of the insulating container via a second cover. 4. The structure according to claim 1, wherein the MoCu material is used as the buffer plate of the semiconductor device which is connected to an end to be sealed to the outside and to which a gate signal is applied to the gate contact. A method for manufacturing a semiconductor device according to claim 5. 7. When manufacturing a semiconductor device using a MoCu material, a plurality of semiconductor substrates sandwiched between a pair of heat buffer plates made of the MoCu material are installed in one package to manufacture the semiconductor device. 7. The method for manufacturing a semiconductor device according to claim 1, wherein: 8. The MoCu material is a WMoCu material in which a part or all of Mo in the MoCu material is replaced with W, or a WCu material.
A method of manufacturing a semiconductor device according to claim 7. 9. The MoCu material, WMoCu material, or WCu material is replaced with the MoCu material, WMoCu material,
Alternatively, MoCuAg material, MoAg material, WMoCu in which part or all of Cu in WCu material is replaced with Ag
Ag material, WMoAg material, WCuAg material, or W
9. An Ag material, wherein the Ag material is used.
The method for manufacturing a semiconductor device according to any one of the above. 10. The MoCu material, WMoCu material, W
Cu material, MoCuAg material, MoAg material, WMoC
The amount of Cu, Ag, or CuAg in the uAg material, WMoAg material, WCuAg material, or WAg material is:
The method according to claim 1, wherein the semiconductor device occupies 0.5% by volume to 50% by volume. 11. A power converter incorporating a semiconductor element manufactured by the manufacturing method according to claim 1.