JP2003234499A - Optical coupling semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupling semiconductor device and its manufacturing method wherein an optical coupling semiconductor device having superior insulating characteristic can be formed in the state free from danger of FUV expose of a worker, manufacturing cost can be reduced by reducing activation treatment time by FUV, and cost of manufacturing equipment is low. <P>SOLUTION: This manufacturing method is provided with a process wherein a light emitting element 2 and a light receiving element 3 which are arranged at a prescribed interval on a lead frame 4 are coated with optical coupling material 7 composed of silicon resin, in which diphenyl siloxane of 1-20 mol% is added to polydimethyl siloxane which has transmissivity of at least 90% to radiant ion rays in a range from ultraviolet to infrared; a process wherein irradiation of far-ultraviolet rays whose peak wavelength is at most 180 nm is performed for 10 sec under an atmosphere, whose oxygen concentration is at most 5 vol.% after coating is performed with the optical coupling material 7; and a process wherein sealing is performed with sealing material 10 which has reflectivity of at least 90% to radiant ion rays in the range from ultraviolet to infrared after irradiation of far-ultraviolet rays is performed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type optically coupled semiconductor device having a single mold structure and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a reflection type optically coupled semiconductor device having a single mold structure includes a light emitting element that emits radiation from an ultraviolet region to an infrared region when a voltage is applied, and a light receiving element that has a light receiving sensitivity to the radiation emitted by the light emitting device. Are fixed to respective predetermined positions of the lead frame, and further, the light emitting element and the light receiving element are covered with an optical coupling material made of a silicone resin having a transparency to ultraviolet rays to infrared rays, which is obtained by polymerizing dimethylsiloxane, and Furthermore, the structure is such that it is sealed with a white epoxy resin sealing material having a reflectance of 50% or more with respect to radiation in the ultraviolet to infrared regions.

When sealing with a sealing material,
The surface of the light-coupled material, which covers the light emitting element and the light receiving element and is cured, is irradiated with deep ultraviolet rays (FUV) of wavelengths 254 nm and 185 nm emitted from the low-pressure mercury lamp having the wavelength distribution shown in FIG. 7 for about 15 minutes. By performing the activation treatment, a covalent chemical bond is formed between the silicone resin, which is an optical coupling material, and the white epoxy resin, which is a sealing material.
Interfacial peeling is less likely to occur between the two. In addition, the dielectric strength also increased, and dielectric breakdown occurred at 5 kV to 6 kV.
Dielectric breakdown did not occur even when a voltage of 0 kV or higher was applied.

However, in the optical coupling semiconductor device thus formed, the coefficient of thermal expansion of the silicone resin is 3.64 × 10 ⁻⁴ / ° C. and the coefficient of thermal expansion of the white epoxy resin is 2.50 × 10 ^−5. / ° C and the difference in the coefficient of thermal expansion between the two in close contact are about 10 times, and the tensile stress is always present in the silicone resin at room temperature. Due to the variation in the characteristics of the silicone resin, the insulation of the optically coupled semiconductor device is insulated. This is a factor that deteriorates the characteristics and reliability.

On the other hand, when the surface of the cured silicone resin as described above is irradiated with FUV for activation treatment, the peak emission wavelength of the low-pressure mercury lamp used is wavelength 25.
Since it is 4 nm and 185 nm, the photon energy is low, and it is necessary to take a long activation time in order to secure a good insulating property, and the processing time becomes long and the manufacturing cost is increased. In addition, since there is little absorption by oxygen in the air and the effective distance is as long as 15 cm to 20 cm, there is a high possibility that the worker will be exposed to radiation, which may cause a cancer, and it is necessary to pay close attention to the work. It was

Therefore, the activation time can be shortened to 60 seconds or less by using, for example, a xenon (Xe) type excimer lamp as the FUV light source and shortening the peak wavelength to 180 nm or less as shown in FIG. The effective distance in air can be set to 20 mm or less, and the safety of the worker can be secured.

However, by shortening the peak wavelength to 180 nm or less, the FUV is absorbed by oxygen in the air to generate ozone as shown in FIG. 9, and the FUV increases as the distance from the FUV light source increases. The illuminance is reduced. For this reason, the margin of design of the manufacturing apparatus is reduced, and it becomes necessary to increase the number of FUV light sources from one lamp to two, and the manufacturing apparatus cost is increased.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an object of the present invention is to provide an optically coupled semiconductor device which has a small variation in the characteristics of the optically coupled material and good insulation characteristics. In addition, it is possible to improve the reliability, to eliminate the risk of FUV exposure of the worker when forming the optically coupled semiconductor device, and to sufficiently secure the safety of the work. (EN) Provided are an optically coupled semiconductor device and a method for manufacturing the same, which can reduce the manufacturing cost by shortening the time of the activation process, and which does not require multiple lighting of the FUV light source and thus does not increase the cost of the manufacturing apparatus. Especially.

[0009]

In the optically coupled semiconductor device and the method of manufacturing the same according to the present invention, an optically coupled semiconductor device includes a light emitting element and a light receiving element which are arranged on a frame with a predetermined distance from each other. A polydimethylsiloxane having a transmittance of 90% or more for external radiation is coated with a photocoupling material made of a silicone resin in which 1 to 20 mol% of diphenylsiloxane is added, and the surface of the photocoupling material is exposed to deep ultraviolet rays for a predetermined time. After irradiation, the optical coupling material is sealed with a sealing material having a reflectance of 90% or more with respect to radiation in the ultraviolet region to the infrared region, and the optical coupling material has a tensile strength of 0.3 MPa or more. And an elongation of 150% or more, and further, the peak wavelength of the far ultraviolet rays is 180 nm or less, and the irradiation time is 10 seconds or less. According to the method of manufacturing an optically coupled semiconductor device, a light emitting element and a light receiving element which are arranged on a frame with a predetermined distance from each other are provided in an amount of 90% with respect to radiation in the ultraviolet region to the infrared region. Diphenylsiloxane is added to polydimethylsiloxane having the above transmittance.
A step of coating with a photo-bonding material made of a silicone resin added by ˜20 mol%, a step of irradiating with a deep ultraviolet ray for a predetermined time in an atmosphere having an oxygen concentration of 5 vol% or less after coating with a photo-bonding material, and an ultraviolet ray after irradiating with a deep ultraviolet ray. The method further comprises a step of sealing with a sealing material having a reflectance of 90% or more with respect to radiation in the infrared region to the infrared region, and further, the peak wavelength of the far ultraviolet rays is 180 nm or less. And the irradiation time is 10 seconds or less. Further, when irradiating the far-ultraviolet ray, the far-ultraviolet ray directly emitted from a radiation source of the far-ultraviolet ray is provided so as to face the radiation source. The method is characterized in that far ultraviolet rays reflected from the reflector are irradiated.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
It will be described with reference to FIGS. 1 is a vertical cross-sectional view showing an optically coupled semiconductor device, FIG. 2 is a cross-sectional view showing an FUV irradiation step, and FIG. 3 is a view showing a relationship between atmospheric pressure (O ₂ concentration in the atmosphere) and water contact angle. FIG. 4 is a diagram showing the relationship between tensile strength and insulation breakdown voltage defective rate of silicone resin at a constant elongation rate, FIG. 5 is a sectional view showing a modified form of the FUV irradiation step, and FIG. 6 is an optically coupled semiconductor. It is a longitudinal section showing a modification of a device.

1 to 6, in a reflection type optically coupled semiconductor device 1 having a single mold structure, a light emitting element 2 such as an LED which emits radiation from an ultraviolet region to an infrared region when a voltage is applied, and the light emitting device 2 emits the radiation. A light-receiving element 3 such as a photodiode having a light-receiving sensitivity to radiation is attached to each of the mounting portions 4a and 4b of the lead frame 4 made of, for example, copper (Cu) or a copper alloy, by using the conductive paste 5
It is configured by being fixed by. further,
The light emitting element 2 and the light receiving element 3 are provided with respective electrode portions 2a,
3a is connected to an inner lead portion (not shown) of the lead frame 4 by using, for example, gold (Au) lead wires 6a and 6b.

Further, the light emitting element 2 and the light receiving element 3 fixed on the lead frame 4 are made of diphenylsiloxane of 5 m.
It is covered with an optical coupling material 7 made of a silicone resin having transparency to ultraviolet to infrared radiation obtained by polymerizing dimethylsiloxane added in an amount of ol%. After curing the optical coupling material 7, the inside of the chamber 8 is cured. It is housed and the outer surface of the optical coupling material 7 is activated.

The activation treatment is carried out by irradiating the outer surface of the photocoupling material 7 with deep ultraviolet rays (FUV). In the step, first, the atmosphere in the chamber 8 is changed to nitrogen gas (N
₂ ) A low oxygen concentration atmosphere is created by sending a forming gas having a base oxygen (O ₂ ) concentration of 5 vol% or less into the chamber 8. Then, for example, xenon (X
e) FUV light source 9 using a type excimer lamp 10
Light for only a second, and use optical coupling material 7 in a low oxygen concentration atmosphere.
The outer surface of the is irradiated with FUV having a peak wavelength of 172 nm for 10 seconds.

Regarding the activation state of the outer surface of the optical coupling material 7, the relation between the atmospheric pressure: atm (oxygen concentration:%) and the activation effect is the contact angle between the glass plate and water. As a result of verification in the atmosphere based on the fact that they are equivalent in a high concentration state, the FUV illuminance is 6.7 mW / cm.
² , the irradiation distance was 5 mm, and the contact angle was measured while changing the irradiation time. As shown in FIG.
The characteristic line X ₁₀ was obtained in the case of second, and the characteristic line X ₅ was obtained in 5 seconds. As a result, there is a minimum value of the contact angle of water at a point where the oxygen concentration is about 0.2%, and the contact angle of water is reduced by lowering the oxygen concentration from the atmospheric state, and the activation process is promoted. I understand. Then, in order to obtain the best active state, it is preferable to set the oxygen concentration to about 0.2 vol%, but practically, the oxygen concentration may be set to 0.05 vol% to 5 vol%. The irradiation time is also 10 seconds or less, preferably 5 seconds to 10 seconds.
It may be about a second.

After that, the lead frame 4 including the light emitting element 2 and the light receiving element 3 on which the photocoupling material 7 has been activated is taken out from the chamber 8 and is 50% or more, preferably 50% or more, with respect to the radiation from the ultraviolet region to the infrared region. Is a white epoxy resin encapsulating material 10 having a reflectance of 90% or more.
The whole is sealed, and the optically coupled semiconductor device 1 in which only the outer leads (not shown) extend is formed.

With the above-mentioned structure, FUV irradiation is performed in the chamber 8, there is no fear of FUV exposure of the worker, and sufficient work safety can be ensured. Furthermore, the activation treatment of the optical coupling material 7 is irradiation of FUV in an atmosphere of low oxygen concentration, and a large distance from the FUV light source 9 can be taken, so that it is possible to increase the margin in the design of the manufacturing apparatus. Irradiation can be shortened to 10 seconds or less, and the FUV light source 9 can be intermittently lit instead of being continuously lit. Therefore, the life of the FUV light source 9 can be extended and maintenance is not required, and the manufacturing cost can be reduced. Can be reduced.

Further, when the insulating characteristics of the above-mentioned structure are examined, the dielectric strength does not cause dielectric breakdown even when a voltage of 10 kV or more is applied, and has good insulating characteristics. Further, with respect to the optical coupling material 7 made of a silicone resin, the state of the withstand voltage (BVs) defect rate of the optical coupling semiconductor device 1 in which the resin characteristics after the surface is irradiated with FUV is combined with the tensile strength and the elongation rate is examined. The results shown in FIG. 4 were obtained.

That is, when the elongation rate is 100%, the dielectric strength failure rate with respect to the tensile strength is as shown by the characteristic line Y ₁₀₀ , when the elongation rate is 150%, it becomes the characteristic line Y ₁₅₀ , and when the elongation rate is 200%. It becomes like a characteristic line Y ₂₀₀ . Therefore, the resin characteristics of the optical coupling material 7 are set to have an elongation of 1
By setting the tensile strength to 50% or more and the tensile strength to 0.3 MPa or more, the characteristic variation becomes small, and it is possible to stably obtain a high dielectric strength while maintaining a low withstand voltage failure rate. 0.5 MPa to 2 M
By setting the pressure to Pa, it is possible to improve the quality, and the formed optical coupling semiconductor device 1 has higher reliability.

In the above embodiment, the activation treatment of the surface of the optical coupling material 7 is performed by the direct irradiation FUV from the FUV light source 9. However, for example, as in the modification shown in FIG. The FUV reflecting member 11 is disposed so as to face the FUV light source 9, and the FUV light source 9 and the FUV reflecting member 11 are arranged.
The FUV irradiation step may be performed by placing the optical coupling material 7 between them. By doing so, not only the direct FUV light emitted from the FUV light source 9 but also the surface portion of the optical coupling material 7 which is a shadow for the FUV light source 9 is reflected directly or indirectly from the FUV reflecting member 11. FUV irradiation by the reflected FUV can be performed, an efficient activation process can be performed, and the device cost can be reduced.

Further, although the optically coupled semiconductor device 1 in the above-mentioned embodiment has a reflection type structure, it is not limited to this, and for example, the optically coupled semiconductor device 12 having an opposed type structure as shown in a modification of FIG. 6 and the like. But it's okay.

Furthermore, regarding the formation of the low oxygen concentration atmosphere during the activation process in the above-described embodiment, the chamber 8 is kept in a decompressed state with the atmospheric configuration, or N
_It may be created by a method such as purging _two gases.

[0022]

As is apparent from the above description, according to the present invention, an operator can obtain an optically coupled semiconductor device having less variation in the characteristics of the optically coupled material, good insulating characteristics, and improved reliability. It can be formed in a work environment where there is no risk of FUV exposure and the safety is sufficiently secured, and because activation processing can be performed in a short time, manufacturing costs can be reduced, and multiple lamps with FUV light sources can be used. There is an effect that it is not necessary to make the manufacturing cost higher and the cost of the manufacturing apparatus is not increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an optically coupled semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an FUV irradiation step in one embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the atmospheric pressure (O ₂ concentration in the atmosphere) and the contact angle of water according to the embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between tensile strength and insulation breakdown voltage defective rate at a constant elongation rate of a silicone resin according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a modification of the FUV irradiation step according to the embodiment of the present invention.

FIG. 6 is a vertical sectional view showing a modification of the optically coupled semiconductor device according to the embodiment of the present invention.

FIG. 7 is a spectral distribution diagram of a low-pressure mercury lamp according to a conventional technique.

FIG. 8 is a spectral distribution diagram of a xenon type excimer lamp.

FIG. 9 is a diagram showing a relationship between FUV illuminance and irradiation distance.

[Explanation of symbols]

1, 12 ... Optically coupled semiconductor device 2 ... Light emitting element 3 ... Light receiving element 4 ... Lead frame 7 ... Optical coupling material 8 ... Chamber 9 ... FUV light source 10 ... Sealing material 11 ... FUV reflecting member

Continued front page    (72) Inventor Kenichi Tanishita             Fukuoka Prefecture Kitakyushu City Kokurakita-ku Shimonitsu 1-10-10             No. 1 Toshiba Kitakyushu Factory F-term (reference) 4M109 AA02 BA01 CA05 CA21 EA02                       EA10 EA15 EC11 EC12 EE12                       EE13 GA01                 5F061 AA02 BA01 CA05 CA21 DE03                       FA01                 5F089 AB01 AB03 AC15 DA14 EA04

Claims (5)

[Claims] 1. A light-emitting element and a light-receiving element, which are arranged on a frame at a predetermined distance from each other, wherein diphenylsiloxane is added to polydimethylsiloxane having a transmittance of 90% or more for radiation in the ultraviolet region to the infrared region. A seal having a reflectance of 90% or more with respect to radiation from the ultraviolet region to the infrared region is obtained by coating the surface of the photocoupling material with deep ultraviolet rays for a predetermined period of time by coating with 20 mol% of a silicone resin-containing photocoupling material. An optical coupling semiconductor device, which is sealed with a stop material, wherein the optical coupling material has a tensile strength of 0.3 MPa or more and an elongation of 150% or more. 2. The deep ultraviolet has a peak wavelength of 180 nm.
2. The optically coupled semiconductor device according to claim 1, wherein the irradiation time is 10 seconds or less. 3. A light emitting element and a light receiving element, which are arranged on a frame with a predetermined distance therebetween, wherein polydimethylsiloxane having a transmittance of 90% or more for radiation in the ultraviolet region to the infrared region has 1 to 1 diphenylsiloxane. A step of coating with an optical coupling material made of a silicone resin added with 20 mol%, a step of irradiating with deep ultraviolet rays for a predetermined time in an atmosphere with an oxygen concentration of 5 vol% or less after coating with the optical coupling material, and an ultraviolet region after irradiation with deep ultraviolet rays. From 90 to infrared radiation
A method for manufacturing an optically coupled semiconductor device, comprising a step of sealing with a sealing material having a reflectance of at least%. 4. The deep ultraviolet has a peak wavelength of 180 nm.
The method for manufacturing an optically coupled semiconductor device according to claim 3, wherein the irradiation time is 10 seconds or less. 5. When irradiating the far-ultraviolet rays, direct-ray far-ultraviolet rays from a radiation source of the far-ultraviolet rays and reflected far-ultraviolet rays from a reflector provided so as to face the radiation source are emitted. The method of manufacturing an optically coupled semiconductor device according to claim 3, wherein