JP2755383B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device which maintains excellent reliability even in a high-temperature atmosphere and does not cause a malfunction of a memory due to a radioactive substance. [Prior Art] Semiconductor elements such as transistors, ICs and LSIs are generally encapsulated with an epoxy resin composition to form semiconductor devices. The epoxy resin has been used for encapsulation of a semiconductor device because of its good electrical properties, moisture resistance, adhesiveness and the like, and has achieved good results. However, in recent years, semiconductor devices have been used in large quantities in many outdoor devices such as automobiles, and as the output of semiconductor devices has increased due to the increase in size and integration thereof, there has been a greater demand for semiconductor devices than ever before. In recent years, many semiconductor devices have been required to have high heat resistance, especially storage reliability at high temperatures which has not been a problem in the past, and at the same time, it has been required to prevent malfunctions of memories caused by radioactive materials. ing. [Problems to be Solved by the Invention] In order to improve such heat resistance, conventionally, it has been carried out by increasing the flame retardancy of an epoxy resin used for sealing. That is, by combining the brominated epoxy resin and antimony oxide into the epoxy resin composition, the flame retardancy of the cured epoxy resin composition is increased, thereby improving the heat resistance of the sealing resin. I'm wearing The combination of the above brominated epoxy resin and antimony oxide shows good results in terms of flame retardancy. However, there is a problem in terms of storage stability at high temperatures. That is, in a high temperature state, hydrogen bromide is generated due to the thermal decomposition of the brominated epoxy resin, and this hydrogen bromide reacts with the junction between the gold wire of the semiconductor element and the aluminum pad to promote the formation of an alloy. This leads to an increase in the electric resistance value, resulting in poor conduction. In addition, with the recent increase in capacity and density of semiconductor memory, the inconvenience that the memory malfunctions due to alpha rays emitted from radioactive substances such as U and Th contained in the encapsulation resin has occurred. I have. As described above, in the conventional semiconductor device, there is no problem in terms of flame retardancy, but there is a problem in terms of reliability when left in a high temperature state, particularly when left for a long time. In addition, there is a problem that a memory malfunctions due to a radioactive substance contained in silica, antimony oxide, and the like existing in the sealing resin. The present invention has been made in view of such circumstances, and maintains excellent reliability even when left in a high-temperature atmosphere for a long time.
It is another object of the present invention to provide a semiconductor device which does not cause a malfunction of a memory due to a radioactive substance. [Means for Solving the Problems] To achieve the above object, a semiconductor device of the present invention encapsulates a semiconductor element using an epoxy resin composition containing the following components (A) to (F). Take the configuration to do. (A) Epoxy resin. (B) a phenolic resin. (C) Brominated epoxy resin. (D) Antimony oxide powder having a U and Th content of 10 ppb or less. (E) Fused silica powder having a U and Th content of 10 ppb or less. (F) Bi hydroxide, Bi oxide, Al hydroxide and Al
At least one compound selected from the group consisting of oxides of That is, the present inventors have conducted a series of studies in order to achieve the above object, and as a result, the halogen compound gas generated during the thermal decomposition of the brominated epoxy resin as a flame retardant is Bi, Al water. Oxides and hydrated oxides are effectively trapped, ensuring reliability under high temperature atmosphere. The inventors have also found that the cause of the malfunction of the memory is caused by radioactive substances in antimony oxide and fused silica, and that when the content is suppressed to 10 ppb or less, the malfunction of the memory disappears, and the present invention has been achieved. The epoxy resin composition used in the present invention comprises an epoxy resin (component A), a phenol resin (component B), a brominated epoxy resin (component C), and an antimony oxide powder (D) having a U and Th content of 10 ppb or less. Component), fused silica powder having a U and Th content of 10 ppb or less (component E) and at least one selected from the group consisting of Bi hydroxide, Bi hydrated oxide, Al hydroxide and Al hydrated oxide. It is obtained by using one compound (component F) and is usually in the form of a powder or a tablet obtained by compressing it. The epoxy resin serving as the component A of the epoxy resin composition is not particularly limited, and various types of conventionally used epoxy resins such as a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, and a bisphenol A type epoxy resin can be used. Epoxy resin. These epoxy resins may be used alone or in combination. Among the epoxy resins mentioned above, preferred epoxy resins are novolak type epoxy resins having an epoxy equivalent of 170 to 300, such as phenol novolak side epoxy resin,
Cresol novolak type epoxy resin and the like can be mentioned. The phenol resin of the component B serves as a curing agent for the epoxy resin, and phenol novolak resin, cresol novolak resin and the like are preferably used. These phenolic resins have a softening point of 50-110 ° C,
It is preferable that the hydroxyl group equivalent is 70 to 150. One or both of the above epoxy resins or phenolic resins have the following general formula (1) When reacted with the organopolysiloxane represented by
The effect of improving crack resistance and temperature cycle resistance can be obtained. However, it is somewhat disadvantageous in terms of heat resistance. However, by using the F component, the disadvantage of heat resistance is eliminated and excellent heat resistance can be obtained. As the brominated epoxy resin of the component C, it is desirable to use one having an epoxy equivalent of 420 or more, preferably 420 to 550. Particularly, the use of a brominated bisphenol-type epoxy resin as the brominated epoxy resin brings good results. When the epoxy equivalent is less than 420, not only the tendency of the resin to be inferior in heat resistance is seen,
This is because a hydrogen halide gas is also easily generated. The amount of the brominated epoxy resin used is preferably set in the range of 1 to 10% in the resin component (A + B + C component) of the epoxy resin composition. That is, if the amount of the brominated epoxy resin is less than 1%, the effect of improving the flame retardancy becomes insufficient, while if it exceeds 10%, the generation of hydrogen halide gas tends to increase, which tends to adversely affect the semiconductor element. Because it can be done. The mutual use ratio of the phenolic resin and the epoxy resin is appropriately selected from the relationship with the epoxy equivalent of the epoxy resin, and is set so that the equivalent ratio of the phenolic hydroxyl group to the epoxy group is in the range of 0.5 to 1.5. Is preferred. If the equivalent ratio is out of the above range, the heat resistance of the cured epoxy resin composition obtained tends to decrease. The antimony oxide powder serving as the component D has a U and Th content of 10 ppb or less. As such antimony oxide powder, the average particle diameter is 0.1 to 30 μm, and setting the maximum particle diameter to 44 μm or less increases the fluidity of the epoxy resin composition and shortens the burr during molding. Is preferred. And the U and Th content needs to be 10 ppb or less. If it exceeds 10ppb, it will cause a malfunction of memory. The fused silica powder as the E component also has a U, Th content of 10
It must be less than ppb. Something like this
The silica can be produced by various methods known as a method for producing fumed silica, for example, thermal decomposition or hydrolysis of silicon compounds such as silicon tetrachloride, trichlorosilane, methylchlorosilane, and methylmethoxysilane. In this case, if the compound as a raw material is purified in advance, a fused silica powder in which the radioactive substance is reduced to 10 ppb or less can be easily produced. In such a fused silica powder, spherical silica is used in an amount of 5 to 100% by weight in order to increase the fluidity of the epoxy resin composition and shorten the burr during molding.
(Hereinafter abbreviated as “%”), and it is preferable to set the average particle size of the fused silica to 1 to 30 μm and the maximum particle size to 96 μm or less. The spherical silica preferably has an aspect ratio (major axis / minor axis) of 1 to 1.3. Such materials can be obtained, for example, by melting synthetic or natural quartz powder in a flame using a combustible gas such as hydrogen or propane and oxygen gas, or by hydrolyzing tetraethoxysilane or tetramethoxysilane. It can be produced by sintering or melting the product obtained or hydrolyzing it. The F component is at least one compound selected from the group consisting of a hydroxide of Bi, a hydroxide of Bi, a hydroxide of Al, and a hydroxide of Al. Such compounds are:
From the viewpoint of dispersibility in the epoxy resin composition, it is preferable that the average particle size is 0.5 to 30 μm and the maximum particle size is 74 μm or less. The content of the F component is 1 to 1 with respect to the resin component (A + B + C) of the epoxy resin composition.
It is preferable to set it to 10%. That is,
If the amount is less than 1%, the effect of improving the high-temperature storage characteristics will not be sufficiently exhibited, and if it exceeds 10%, a phenomenon of lowering the moisture resistance will be observed. Representative examples of such an F component include bismuth hydroxide, aluminum hydroxide, hydrous dibismuth trioxide, and hydrous dialuminum trioxide. Such compounds may be used alone or in combination. The epoxy resin composition used in the present invention contains, if necessary, other additives conventionally used in addition to the above-mentioned components A to F. Examples of the other additives include a curing accelerator, a release agent, a coloring agent, and a silane coupling agent. Examples of the curing accelerator include tertiary amines, quaternary ammonium salts, imidazoles, organic phosphorus compounds and boron compounds. These compounds are used alone or in combination. Examples of the release agent include conventionally known long-chain carboxylic acids such as stearic acid and palmitic acid, metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, and waxes such as carnauba wax and montan wax. Can be used. The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, the above A
-F component and the above-mentioned other additives are appropriately blended, the mixture is melted and mixed in a heating state by a kneading machine such as a mixing roll machine, and then cooled to room temperature, and then pulverized by a known means. The desired epoxy resin composition can be obtained by a series of steps of tableting. The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding. The semiconductor device obtained in this way has excellent performance of maintaining reliability when left at a high temperature and also preventing malfunction of a memory. [Effects of the Invention] As described above, the semiconductor device of the present invention comprises a brominated epoxy resin (C component), an antimony oxide powder (D component) having a U and Th content of 10 ppb or less, and a fused silica powder (E component). ) And a special epoxy resin composition containing a compound (F component) composed of a hydroxide or a hydrated oxide of Bi, Al, etc., and the F component in the sealing resin has a high temperature. It has excellent reliability when left at high temperatures because it captures halogen compounds generated when left for a long time in an atmosphere. Further, since the content of the radioactive substance is greatly reduced, no malfunction of the memory occurs. Next, examples will be described together with comparative examples. [Examples 1 to 11, Comparative Examples 1 to 4] First, raw materials as shown in Table 1 below were prepared. Next, the above-mentioned raw materials were blended in the proportions shown in Table 2 below, kneaded with a mixing roll machine, cooled and pulverized to obtain a desired powdery epoxy resin composition. The cured product characteristics of the powdery epoxy resin composition obtained as described above were examined and are shown in Table 3 below. In Table 3, the spiral flow is EMMI
-66 and gel time were measured according to JIS-K-5966. The linear expansion coefficient and the glass transition temperature were measured by TMA (manufactured by Rigaku Corporation). The flexural modulus and flexural strength were measured with a Tensilon universal tester (manufactured by Toyo Baldwin Co., Ltd.). The volume resistivity was measured according to JIS-K-6911. Also,
The measurement of element failure in a high temperature state was performed by assembling a semiconductor device by sealing a semiconductor element with a resin, exposing a total of 20 devices to a high temperature, and determining and evaluating the number of conduction failures. In the TCT test, the semiconductor element was sealed with a resin, a semiconductor device was assembled, and a temperature cycle test was performed 2000 times at −50 ° C./5 minutes to 150 ° C./5 minutes to measure the number of generated cracks. The α dose is an α-ray counter (Sumitomo Chemical Co., Ltd.)
It measured using. From the results in Table 3, it can be seen from the results of Table 3 that the number of defective elements when the product is left at high temperature and the TCT test result show that the reliability of the device when left at high temperature is high and that the α dose that causes memory malfunction is small. Recognize.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 61/10 C08L 61/10 (72) Inventor Minoru Minoru 1-2-1 Shimohozumi, Ibaraki-shi, Osaka Nitto Denki Kogyo Co., Ltd. In-house (72) Inventor Fujio Kitamura 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nichito Electric Industry Co., Ltd. (72) Inventor Kazuo Ika 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Electric (56) References JP-A-60-226147 (JP, A) JP-A-62-207319 (JP, A) JP-A-62-59626 (JP, A) JP-A-57-195151 (JP , A)

Claims (1)

(57) [Claims] A semiconductor device in which a semiconductor element is sealed using an epoxy resin composition containing the following components (A) to (F). (A) Epoxy resin. (B) a phenolic resin. (C) Brominated epoxy resin. (D) Antimony oxide powder having a U and Th content of 10 ppb or less. (E) Fused silica powder having a U and Th content of 10 ppb or less. (F) at least one compound selected from the group consisting of a hydroxide of Bi, a hydrated oxide of Bi, a hydroxide of Al and a hydrated oxide of Al. 2. 2. The semiconductor device according to claim 1, wherein the fused silica contains 5 to 100% by weight of spherical silica. 3. Fused silica has an average particle size of 1 to 30 μm and a maximum particle size of 96
Claim 1 or Claim 2 wherein the thickness is not more than μm.
13. The semiconductor device according to claim 1. 4. At least one of the epoxy resin and the phenol resin has the following general formula (1) The semiconductor device according to any one of claims 1 to 3, wherein the semiconductor device is reacted with an organopolysiloxane represented by the following formula: 5. The compound of the above component (F) has an average particle size of 0.5 to 30 μm,
5. The semiconductor device according to claim 1, wherein the maximum particle size is 74 μm or less. 6. 6. The semiconductor device according to claim 1, wherein the epoxy resin as the component (A) is a novolak type epoxy resin having an epoxy equivalent of 170 to 300. 7. The semiconductor device according to any one of claims 1 to 6, wherein a phenol resin having a softening point of 50 to 110 ° C and a hydroxyl equivalent of 70 to 150 is used as the phenol resin as the component (B). 8. 8. The semiconductor device according to claim 1, wherein the brominated epoxy resin as the component (C) is a brominated epoxy resin having an epoxy equivalent of 420 or more. 9. The amount of the brominated epoxy resin used as the component (C) is not more than the epoxy resin (A), the phenol resin (B),
In the total amount (A + B + C) of the brominated epoxy resin (C),
9. The semiconductor device according to claim 1, wherein the content is 1 to 10% by weight. 10. 10. The semiconductor device according to claim 1, wherein the antimony oxide powder as the component (D) has an average particle diameter of 0.1 to 30 [mu] m and a maximum particle diameter of 44 [mu] m or less. 11. The compounding amount of the compound of the component (F) is 1 to 10% by weight based on the total amount (A + B + C) of the epoxy resin (A), the phenol resin (B), and the brominated epoxy resin (C). 11. The semiconductor device according to any one of items 1 to 10.