JP2002064165A - Diode and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in breakdown voltage of a diode during process of manufacturing. SOLUTION: In a structure of a pn-junction exposed part of a diode molded with undercoat resin and overcoat resin, a silicon rubber with coefficient of elasticity lower than the undercoat and overcoat resin is inserted between the undercoat resin and the overcoat resin. Delamination between the silicon and the undercoat resin cannot be caused by tightness between the undercoat resin and the overcoat resin. A decrease in breakdown strength of the diode can be prevented, so the diode can be manufactured stably with high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly, to a diode and a method for manufacturing the same.

[0002]

2. Description of the Related Art Various techniques have been proposed for increasing the withstand voltage and the reliability of a resin-molded semiconductor device in which a diode in which a plurality of pn diode pellets are laminated with a brazing material is molded with a resin.

For example, as a technique for suppressing the generation of microplasma in a stacked high withstand voltage semiconductor device, Japanese Patent Laid-Open No.
There is a technique described in JP-A-209150. According to this conventional technique, the volume resistivity of the surface protective layer provided on the semiconductor surface is selected so that the current flowing through the surface protective layer when a reverse voltage is applied is larger than the leak current of each diode chip. Generation of noise can be suppressed.

Further, as a technique for increasing the withstand voltage of a resin molded semiconductor device, there is a technique described in Japanese Patent Application Laid-Open No. 58-48955. According to this conventional technique, a plurality of stacked semiconductor chips are made of a brazing material that contains 90% or more of lead, has an average thickness of 60 to 100 μm, and has a portion protruding from the side surfaces of the plurality of semiconductor chips. By connecting, defects such as a decrease in withstand voltage can be solved.

[0005]

However, in the above prior art, no consideration has been given to the problem that the blocking characteristic varies every time a plurality of insulators are formed in the diode manufacturing process.

An object of the present invention is to provide a diode and a method of manufacturing the same which have solved the problems of the conventional semiconductor device and the method of manufacturing the same.

Specifically, the object of the present invention is to provide a resin mold diode to which a high reverse voltage is applied, without reducing the withstand voltage in each step of applying and curing a resin, and at the same time, ensuring various reliability. An object of the present invention is to provide an excellent diode having no change in blocking characteristics even in a test and a method of manufacturing the same.

[0008]

In a diode according to the present invention, a first insulator covering a pn junction exposed at an end face of a semiconductor pellet and a second insulator covering an upper portion of the first insulator are provided.
An insulator, interposed between the first insulator and the second insulator;
And a third insulator having a lower elastic modulus than the second insulator. According to the present invention, the third insulator having a low elastic modulus is formed of the first insulator.
Since it serves as a buffer against the stress between the insulator and the second insulator, the adhesion between the first insulator and the pn junction or the adhesion between the insulators is improved. Therefore, the reliability of electrical characteristics such as withstand voltage and leak current is improved.

A preferable value of the elastic modulus is such that the elastic modulus of the first insulator and the second insulator is 10 ¹⁰ dyn / cm ² or more,
The insulator has an elastic modulus of 10 ⁶ dyn / cm ² or more and less than 10 ¹⁰ dyn / cm ² . Further, a preferable insulator material is that the first insulator is any of polyimide silicone, glass and silicon dioxide, the second insulator is any of photopolymer resin, epoxy resin and acrylic resin, and the third insulator is silicone rubber. It is.

The preferred electrode structure of the diode according to the present invention includes a first header and a first header in which the first electrode lead and the second electrode lead contacting the semiconductor pellet are in contact with the semiconductor pellet. And a second header provided separately from the second header. The first insulator covers the pn junction between the first header of the first electrode lead and the first header of the second electrode lead. The third insulator is interposed between the first insulator and the second insulator between the second header of the first electrode lead and the second header of the second electrode lead.

The method of manufacturing a diode according to the present invention includes the following steps. (1) A first step of preparing a semiconductor pellet having a pn junction exposed at an end face. (2) A second step of covering the pn junction with the first insulator. (3) A third step of covering the surface of the first insulator with a third insulator having a lower elastic modulus than the first insulator. (4) A fourth step of covering the surface of the third insulator with a second insulator having a higher elastic modulus than the third insulator.

According to the present invention relating to the above manufacturing method, the third insulator having a low elastic modulus serves as a buffer against the stress between the first insulator and the second insulator. Between the electrodes or between the insulators is improved. Therefore, during the manufacture of the diode, the electrical characteristics such as the breakdown voltage and the leak current of the semiconductor pellet do not deteriorate. Therefore, diodes with high reliability of these electric characteristics can be manufactured with high yield.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view showing a first embodiment of a diode according to the present invention.

In the semiconductor pellet, the p ⁺ -type semiconductor region 3 (third semiconductor region) having a high impurity concentration, and the n-type semiconductor region 1 (the second semiconductor region) having a lower impurity concentration than the p ⁺ -type semiconductor region 3.
A semiconductor region) and an n ⁺ -type semiconductor region 2 (first semiconductor region) having an impurity concentration higher than that of the n-type semiconductor region 1 are formed adjacent to each other, and p ⁺ -type semiconductor regions 3 and n ⁺ located at both ends of the semiconductor pellet. An anode electrode 11 (first electrode) and a cathode electrode 12 (second electrode) are electrically connected to the mold semiconductor regions via the first solder 4 respectively. The first insulating film 6 which is an undercoat resin so as to cover the surfaces of the p ⁺ -type semiconductor region 3, the n-type semiconductor region 1, and the n ⁺ -type semiconductor region 2, the first solder 4, and a part of the anode electrode 11 and the cathode electrode 12. Is formed, and the pn junction exposed on the end face of the semiconductor pellet is covered with the first insulating film 6. Further, a third insulating film 7 is formed so as to cover the first insulating film 6, and an epoxy-based overcoat also serving as a package so as to cover the third insulating film 7 and at least a header portion of the anode electrode 11 and the cathode electrode 12. The second resin
An insulating film 8 is formed.

As the third insulating film 7, an insulator having a lower elastic modulus than the first insulating film 6 and the second insulating film 8, for example, silicone rubber having an elastic modulus of 10 ⁶ to 10 ¹⁰ dyn / cm ² is used. Thus, it is possible to prevent the blocking characteristic from being changed in each manufacturing process for the following reasons, and to obtain a highly reliable diode.

That is, when the undercoat resin 6 is applied and cured, the p ⁺ type semiconductor region 3, the n type semiconductor region 1,
A siloxane bond ({Si—O—Si}) is formed between the surface of the n ⁺ type semiconductor region 2 and the undercoat resin 6 and is stable. For this reason, in the usual process, after the undercoat resin 6 is applied and cured, the blocking characteristics are good.
However, if the undercoat resin 6 is coated and cured without forming the third insulating film 7, the overcoat resin 8 as the second insulating film is molded, and then cured after molding, the undercoat resin 6 and the overcoat resin are formed. 8 and a siloxane bond (≡Si—O—Si
≡) can be done. Although the above siloxane bond is strong,
Depending on the manufacturing process, if the adhesion between the undercoat resin 6 and the overcoat resin 8 is stronger than the adhesion between the semiconductor surface and the undercoat resin, the siloxane between the semiconductor surface and the undercoat resin 6 may be used. The bond ({Si-O-Si}) is broken, and the film may be peeled off on the semiconductor surface to partially form a cavity. Since the electric field locally increases in this hollow portion, a soft waveform such that the leak current increases in a voltage region lower than the voltage indicating the original withstand voltage is shown. Therefore, during the manufacturing process, the third insulating film 7 made of silicone rubber or the like should be formed in order to mold the overcoat resin while maintaining the adhesion due to the siloxane bond between the semiconductor surface and the undercoat resin. Even if the third insulating film 7 and the undercoat resin 6 are siloxane-bonded, the elasticity of the third insulating film 7 is lower than that of the undercoat resin 6, so that the third insulating film 7 has elasticity, so that the semiconductor surface and the undercoat resin 6 have good elasticity. Excellent adhesion can be maintained.

Further, by forming the third insulating film 7, even if the adhesion between the third insulating film 7 and the overcoat resin 8 becomes strong, the elastic modulus of the third insulating film 7 becomes too large. Since it is lower than the coat resin, the third insulating film 7 plays a role of a buffer against stress, and can maintain good adhesion between the semiconductor surface and the undercoat resin 6.

Another effect of the third insulating film 7 is that alkali ions (Na ⁺ ions), which are cations that are harmful to the semiconductor surface, are usually present in the overcoat resin. When heat treatment is performed, this harmful alkali ion may diffuse into the undercoat resin 6 and induce electrons on the semiconductor surface. If electrons exist in excess of the thermal equilibrium state on the semiconductor surface, an electron accumulation layer is formed on the n-type semiconductor surface, and p
^{When a} reverse voltage is applied to the ⁺ n junction, the width of the depletion layer that spreads over the surface of the n-type semiconductor becomes narrower than the inside, so that leakage current increases and abnormalities in blocking characteristics such as a decrease in breakdown voltage appear. This problem can be solved by forming the third insulating film 7 in advance. That is, since the third insulating film 7 has a low diffusion coefficient of harmful alkali ions in the overcoat resin 8, even if heat treatment is performed after molding, alkali ions in the overcoat resin may not be mixed into the undercoat resin 6. In addition, since no excessive electrons are induced on the semiconductor surface, the diode can be produced extremely stably without fluctuation in the blocking characteristics during the manufacturing process. (Embodiment 2) FIG. 2 is a sectional view showing a second embodiment of the diode according to the present invention. In FIG. 2, those having the same reference numerals as those in FIG. In FIG. 1, the anode electrode 11 and the cathode electrode 12 use a single header, but in FIG. 2, the anode electrode 11 has a portion 11a where the diameter of the portion connected to the first solder 4 is larger than the diameter of the other lead wires. And a portion 11b larger than the diameter of the lead wire at an arbitrary distance from this portion
It has a double header. Further, the cathode electrode 12 has a portion 12a where the diameter of the portion connected to the first solder 4 is larger than the diameter of another lead wire, and has a larger diameter than the lead wire at an arbitrary distance from this portion. The double header has a portion 12b. A description will be given of how the adoption of the double header improves the mass productivity of the diode. In FIG. 1, the undercoat resin 6 which is the first insulator is used.
Is applied as an undercoat so as to cover the surfaces of the p ⁺ -type semiconductor region 3, the n-type semiconductor region 1, the n ⁺ -type semiconductor region 2, the first solder 4, and the anode electrode 11 and the cathode electrode 12. A first insulating film 6 made of a resin is formed, a third insulating film 7 is formed so as to cover the first insulating film 6, and a third insulating film 7 and at least a header portion of the anode electrode 11 and the cathode electrode 12 are formed. A second insulating film, which is an epoxy-based overcoat resin also serving as a package, is formed so as to cover the resin. On the other hand, in FIG. 2, the undercoat resin 6 includes the p ⁺ -type semiconductor region 3, the n-type semiconductor region 1, the surface of the n ⁺ -type semiconductor region 2, the first solder 4, the anode electrode 11 a and the cathode electrode 12.
a formed to cover a part of the undercoat resin
Are not in contact with the anode electrode 11b and the cathode electrode 12b. Further, by making the silicone rubber 7 as the third insulator cover the undercoat resin 6 and straddle the anode electrode 11b and the cathode electrode 12b, the undercoat resin is compared with the embodiment shown in FIG. There is an advantage that the contact between the resin 6 and the overcoat resin 8 can be easily prevented.

Therefore, the effect as described with reference to FIG. 1, that is, the third insulating film 7 has, for example, an elastic modulus of 10 ⁶ to 10 ¹⁰ dyn.
/ The use of silicone rubber cm ² or the like is applied to cure the undercoat resin 6, the third insulating film 7 is coated cured, when the heat treatment after the last molded overcoat resin 8 mold, p ⁺ Type semiconductor region 3, n
A siloxane bond (半導体 Si—O—Si) is formed between the surface of the type semiconductor region 1 and the n ⁺ type semiconductor region 2 and the undercoat resin 6.
Iv), the adhesion is high, and even if the adhesion between the third insulator 7 and the overcoat resin 8 is high, the elasticity of the third insulating film is lower than that of the undercoat resin 6 or the overcoat resin. In addition, since the third insulating film plays a role of a buffer against stress, the third insulating film has elasticity, and has an advantage that good adhesion between the semiconductor surface and the undercoat resin 6 can be maintained. (Embodiment 3) FIG. 3 is a sectional view showing a third embodiment of the diode according to the present invention. Two of the semiconductor pellets in which the n ⁺ -type semiconductor region 2 with a high impurity concentration, the n-type semiconductor region 1 and the p ⁺ -type semiconductor region 3 with a high impurity concentration are formed adjacent to each other are:
It has a stack connected via the second solder 5 so that the n-type semiconductor regions 2 of the respective semiconductor pellets are electrically connected. Further, a first electrode 21 and a second electrode 22 are ohmic-connected to the two p ⁺ -type semiconductor regions 3 located at both ends of the stack via the first solder 4. The undercoat resin 6 has an elastic modulus of 10 such as polyimide silicone at the pn junction exposed at the end face of the semiconductor pellet.
¹⁰ / cm ² or more of the first insulator 6 is formed.
Elasticity of the silicone rubber or the like so as to cover the can 10 ⁶ to 10
^A third insulator 7 of ¹⁰ / cm ² is formed, and a second insulator 8 such as an epoxy resin is molded as an overcoat resin. By connecting two pn diodes in series in this manner, a diode exhibiting a bidirectional blocking characteristic can be obtained, and the effect shown in FIG. There is. That is, after the undercoat resin 6 is applied and cured, the third insulating material 7 is formed, so that the third insulating film 7 and the undercoat resin 6 are bonded after the overcoat resin is molded or subjected to a heat treatment after the molding. Even with siloxane bonding, the elasticity of the third insulating film is lower than that of the undercoat resin, so that the third insulating film has elasticity and can maintain good adhesion between the semiconductor surface and the undercoat resin. In addition, the third
By forming the insulating film, even if the adhesion between the third insulating film and the overcoat resin becomes strong,
Since the elastic modulus of the insulating film is lower than that of the overcoat resin,
The third insulating film plays a role of a buffer against stress, and the adhesion between the semiconductor surface and the undercoat resin can be kept good.

Further, since the third insulating film has a low diffusion coefficient of harmful alkali ions in the overcoat resin,
Even if heat treatment is performed after molding, alkali ions in the overcoat resin will not be mixed into the undercoat resin, and excessive electrons will not be induced on the semiconductor surface. And a diode can be produced extremely stably. (Embodiment 4) FIG. 4 is a sectional view showing a fourth embodiment of the diode according to the present invention. 4, the description of the same reference numerals as those shown in FIG. 3 is omitted. In FIG. 3, the first electrode 2
Although a single header is used for the first and second electrodes 22, in FIG. 4, the first electrode 21 has a portion 21a where the diameter of the portion connected to the solder is larger than the diameter of the other lead wires.
And a double header having a portion 21b larger than the diameter of the lead wire at an arbitrary distance from this portion. The second electrode 22 has a portion 22a where the diameter of the portion to be connected to the solder is larger than the diameter of another lead wire, and a portion 22b where the diameter is larger than the diameter of the lead wire at an arbitrary distance from this portion. It has a double header. The reason why the adoption of the double header improves the mass productivity of the diodes is the same as that explained in detail with reference to FIG. That is, in FIG. 4, the undercoat resin 6 includes the p ⁺ -type semiconductor region 3, the n-type semiconductor region 1, the surface of the n ⁺ -type semiconductor region 2, the first solder 4, the second solder 5, the first electrode 21a and the second electrode 21a.
The undercoat resin 6 is formed so as to cover a part of the electrode 22a, so that the undercoat resin 6 does not contact the first electrode 21b and the second electrode 22b. Further, the undercoat resin 6 is formed by completely covering the undercoat resin 6 with the silicone rubber 7 as the third insulator and straddling the first electrode 21b and the second electrode 22b.
There is an advantage that it is easy to prevent the contact with the overcoat resin 8.

Therefore, the effect as described with reference to FIG. 3, that is, the third insulating film 7 has, for example, an elastic modulus of 10 ⁶ to 10 ¹⁰ dyn.
By using / cm ² such as silicone rubber, is applied to cure the undercoat resin, a third insulating film 7 is coated cured, even if the last heat treatment overcoat resin 8 molded after molding, p ⁺ -type A siloxane bond ({Si-O-Si}) is formed between the surface of the semiconductor region 3, the n-type semiconductor region 1, and the n ⁺ -type semiconductor region 2 and the undercoat resin 7.
And the adhesion becomes higher. In addition, even if the adhesion between the third insulating material 7 and the overcoat resin 8 is high, the elasticity of the third insulating film is lower than that of the undercoat resin or the overcoat resin. Since it has a role, it has elasticity and has an advantage that good adhesion between the semiconductor surface and the undercoat resin can be maintained. (Embodiment 5) FIG. 5 is a sectional view showing a fifth embodiment of the diode according to the present invention. 5, the description of the same components as those shown in FIG. 3 is omitted. In FIG. 5, the p ⁺ -type semiconductor region 3a (fourth semiconductor region) having a high impurity concentration, the n-type semiconductor region 1 (fifth semiconductor region), and the p ⁺ -type semiconductor region 3b (sixth semiconductor region) having a high impurity concentration are adjacent to each other. Pn formed
First semiconductor pellet having p structure and n with high impurity concentration
The second semiconductor pellet having the pn structure in which the ⁺ semiconductor region 2, the n-type semiconductor region 1, and the p ⁺ -type semiconductor region 3 having a high impurity concentration are formed adjacent to each other is the p ⁺ -type semiconductor region 3a of the first semiconductor pellet. And the n ⁺ type semiconductor region 2 of the second semiconductor pellet has a stack connected via the second solder 5.
Further, the first electrode 31 ohmically connected to the p ⁺ -type semiconductor region 3a at both ends of the stack via the first solder 4 and the first electrode 31 ohmically connected to the p ⁺ -type semiconductor region 3 via the first solder 4 It has two electrodes 32. A first insulator 6 having a modulus of elasticity of 10 ¹⁰ / cm ² or more such as polyimide silicone is formed as an undercoat resin at the pn junction exposed at the end face of the semiconductor pellet. A third insulator 7 having an elastic modulus of 10 ⁶ to 10 ¹⁰ / cm ² is formed, and a second insulator 8 such as an epoxy resin having an elastic modulus of 10 ¹⁰ / cm ² or more is molded as an overcoat resin. .

With such a configuration, the first
Assuming that the withstand voltage of the pellet has a bidirectional Zener breakdown voltage of 15 V and the withstand voltage of the second pellet is 600 V, a voltage is applied such that the first electrode 31 is positive and the second electrode 32 is negative. When a voltage is applied such that the first electrode 31 is negative and the second electrode is positive, a diode exhibiting a constant voltage characteristic at a Zener breakdown voltage of 15 V can be obtained. .

The present embodiment also has the effects as shown in FIGS. (Embodiment 6) FIG. 6 is a sectional view showing a sixth embodiment of the diode according to the present invention. 6, the description of the same components as those shown in FIG. 5 is omitted. The first electrode 31 is the first
The double header has a portion 31a where the diameter of the portion connected to the solder 4 is larger than the diameter of the other lead wire, and a portion 31b where the diameter of the lead wire is larger than the diameter of the lead wire at an arbitrary distance from this portion. The second electrode 32 has a portion 32a where the diameter of the portion to be connected to the solder is larger than the diameter of the other lead wire, and has a larger diameter than the lead wire at an arbitrary distance from this portion. The double header has a portion 32b.
As described above, by employing the double header, the electrode structure employing the single header shown in FIG.
If the diode electrode structure according to the present invention shown in FIG. 6 is used, the reason why the mass productivity is further improved is the same as that described in detail with reference to FIGS. 2 and 4, and the description is omitted here. (Embodiment 7) FIG. 7 is a sectional view showing a seventh embodiment of the diode according to the present invention. In FIG. 7, the description of the same reference numerals shown in FIG. 1 is omitted. Figure 1, a high impurity concentration p ⁺ -type semiconductor regions 3, n-type semiconductor region 1, n ⁺ -type semiconductor region 2 have been used one semiconductor pellet formed adjacent, p ⁺ -type semiconductor regions 3 And an n ⁺ type semiconductor region via the first solder 4 to the anode electrode 11.
In FIG. 7, a plurality of semiconductor pellets are stacked in series with the second solder 5 interposed therebetween, and p ⁺ is located at both ends of the stack.
Electrode 11 which is ohmic-connected to the semiconductor region 3 via the first solder 4 and a cathode electrode 12 which is ohmic-connected to the n ⁺ -type semiconductor region 2 via the first solder 4 and is exposed on the end face A first insulator 6 having an elastic modulus of 10 ¹⁰ / cm ² or more of polyimide silicone or the like is formed as an undercoat resin for bonding, and an elastic modulus of silicone rubber or the like is 10 ⁶ to ¹⁰ 10 so as to cover the first insulator 6. / Cm ² is formed, and a second insulator 8 such as an epoxy resin is molded as an overcoat resin.

By using a plurality of semiconductor pellets as described above, the breakdown voltage can be increased. (Embodiment 8) FIG. 8 is a sectional view showing an eighth embodiment of the diode according to the present invention. 8, the description of the same reference numerals as those shown in FIG. 7 is omitted. The anode electrode 11 has a portion 11a in which the diameter of the portion connected to the first solder 4 is larger than the diameter of another lead wire, and a portion 11b in which the diameter is larger than the diameter of the lead wire at an arbitrary distance from this portion. The cathode electrode 12 has a portion 12a where the diameter of the portion connected to the solder 4 is larger than the diameter of the other lead wire, and the diameter of the lead wire at an arbitrary distance from this portion. The double header has a larger portion 12b. The reason why the adoption of the double header makes it possible to further improve the mass productivity by adopting the diode electrode structure of the present invention shown in FIG. 8 from the electrode structure adopting the single header shown in FIG. 2, which is the same as that described in detail with reference to FIGS. 4 and 6, and the description is omitted here. (Embodiment 9) FIG. 9 is a cross-sectional view showing a step for manufacturing the diode of the first embodiment. The description of the same components as those shown in FIG. 1 by the reference numerals in FIG. 9 is omitted. The diode assembly shown in FIG.
The surface of the semiconductor is etched by about several μm using H or an alkali of NaOH to remove a strained layer on the surface. Thereafter, the surface is cleaned by pure water washing or the like, and FIG.
As shown in (b), the first insulator 6 having an elastic modulus of 10 ¹⁰ / cm ² or more such as polyimide silicone is applied as an undercoat resin to the pn junction exposed on the end face,
Cure at a temperature of 250 ° C. in a nitrogen atmosphere. Subsequently, as shown in FIG. 9C, a third insulator 7 having an elastic modulus of 10 ⁶ to 10 ¹⁰ / cm ² such as silicone rubber is applied so as to cover the first insulator 6, Curing at a temperature of ° C. in a nitrogen atmosphere. Next, as shown in FIG. 9D, an overcoat resin 8 having an elastic modulus of 10 ¹⁰ / cm ² or more of an epoxy resin or the like is formed by a transfer molding method, and is heated at a temperature of 170 to 250 ° C. after the molding. Carry out after cure.

By using such a manufacturing method,
After application and curing of the undercoat resin, the elastic modulus is 10 ⁶ to
After application and curing of the third insulating material 7 such as silicone rubber of 10 ¹⁰ / cm ² , and after application and curing of the overcoat resin, deterioration and fluctuation of the blocking characteristics are almost eliminated.

FIG. 10 shows experimental data representing the effect of the present invention. The vertical axis of FIG.
The reverse direction applied voltage in μA, that is, the breakdown voltage is shown, and the horizontal axis shows the manufacturing process. As shown in this figure, the withstand voltage is distributed in the range of 620 to 1060 V after the undercoat resin is applied and cured. In the conventional structure to which the present invention is not applied, that is, in the structure in which the third insulator 7 is replaced with the overcoat resin 8 in FIG. 1, after the overcoat resin is molded, the withstand voltage is reduced to 220 to 700 V, and the curing after the molding is performed. Withstands 410 when implemented at 190 ° C
When the temperature is restored to ９930 V, and then recured at 250 ° C. after molding, the breakdown voltage is restored to 600 to 1000 V, but does not recover to the value after application of the undercoat resin.
However, according to the diode shown in FIG. 1 and the manufacturing method shown in FIG. 9 according to the present invention, no characteristic variation due to the manufacturing process, particularly no decrease in withstand voltage is observed, but rather the withstand voltage increases after molding, and further, 190 ° C. after molding. Or 250 ° C
, The withstand voltage tends to increase, and
It maintains a high value of 00 to 1140 V, and there is no fluctuation due to the manufacturing process. In each embodiment, the conductivity type p of the semiconductor region is used.
The effects of the present invention and each embodiment are the same even if the type and the n-type are set to the opposite conductivity types.

[0027]

As described above, according to the present invention, high adhesion at the interface can be maintained without peeling off the film between the semiconductor surface and the undercoat resin.

Further, according to the present invention, there is an effect that excessive accumulation of electrons on the semiconductor surface can be prevented. For this reason, the blocking characteristics of the diode are such that a leakage current is small and a high withstand voltage can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a diode according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the diode according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the diode according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the diode according to the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of the diode according to the present invention.

FIG. 6 is a sectional view showing a sixth embodiment of the diode according to the present invention.

FIG. 7 is a sectional view showing a seventh embodiment of the diode according to the present invention.

FIG. 8 is a sectional view showing an eighth embodiment of the diode according to the present invention.

FIG. 9 is a sectional view showing a step of manufacturing a diode according to the present invention.

FIG. 10 is a diagram showing a variation in the breakdown voltage of the diode according to the present invention in the manufacturing process.

[Explanation of symbols]

1 ... n-type semiconductor region, 2 ... n ⁺ -type semiconductor region, 3 ... p ⁺
Mold semiconductor region, 4 ... first solder, 5 ... second solder, 6 ... first
Insulating film, 7: Third insulating film, 8: Second insulating film, 11: Anode electrode, 12: Cathode electrode, 21, 31, 41: First electrode, 22, 32, 42: Second electrode.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsuyuki Matsuzaki 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Works (72) Inventor Minoru Sugano 3-chome Bentencho, Hitachi-shi, Ibaraki No. 2 Hitachi Haramachi Electronics Co., Ltd. (72) Inventor Kenji Terashima 3-10-2 Bentencho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Haramachi Electronics Co., Ltd. 4M109 AA02 BA01 CA21 EA02 ED03 ED04 ED05 ED06 EE02 EE20

Claims (5)

[Claims] 1. A semiconductor pellet having a pn junction exposed at an end face, a first insulator covering the pn junction, a second insulator covering the first insulator, the first insulator and the first insulator. A third insulator interposed between the second insulators and having a lower elastic modulus than the first insulator and the second insulator;
An insulator. 2. The method according to claim 1, wherein the first insulator and the second insulator have an elastic modulus of 10 ¹⁰ dyn / cm ² or more, and the third insulator has an elastic modulus of 10 ⁶ dyn / cm ² or more. 10 ¹⁰ dyn / cm
Diode that is less than ² . 3. The method according to claim 1, wherein the first insulator is any of polyimide silicone, glass, and silicon dioxide, and the second insulator is one of a photopolymer resin, an epoxy resin, and an acrylic resin; A diode in which the third insulator is a silicone rubber. 4. The semiconductor device according to claim 1, further comprising a first electrode lead and a second electrode lead that are in contact with said semiconductor pellet, wherein each electrode lead has a first header which is a contact portion with said semiconductor pellet and said first header and a second header. A second header provided apart from the first header, wherein the first insulator is disposed between the first header of the first electrode lead and the first header of the second electrode lead; The third insulator covers the pn junction, and the third insulator is provided between the second header of the first electrode lead and the second header of the second electrode lead. 2 Diode interposed between insulators. 5. A first step of preparing a semiconductor pellet having a pn junction exposed at an end face, a second step of covering the pn junction with a first insulator, and a step of covering the surface of the first insulator with the first insulator. A third step of covering with a third insulator having a lower elastic modulus than the first insulator; and a fourth step of covering a surface of the third insulator with a second insulator having a higher elastic modulus than the third insulator. And a process for producing a diode.