KR19980066545A - High heat-resistant encapsulant for semiconductor devices - Google Patents

Abstract

The present invention relates to a high heat dissipating encapsulant for a high heat dissipation semiconductor device for encapsulating a high integration semiconductor device to effectively dissipate heat therein.

High heat-resistant encapsulant for semiconductor devices according to the present invention, 7 to 12% by weight of epoxy resin, 3 to 7% by weight of the curing agent, 0.01 to 0.2% by weight of the curing accelerator, 77.8 to 89.69% by weight of aluminum nitride as a filler (AlN; Aluminum Nitride), 0.1 to 1.0 wt% binder, 0.1 to 1.0 wt% release agent and 0.1 to 1.0 wt% modifier.

Therefore, the present invention can be used to encapsulate a highly integrated, high heat generating semiconductor device, and also has an effect of providing a high heat dissipation encapsulant having improved crack resistance due to signal transmission speed and thermal stress.

Description

High heat-resistant encapsulant for semiconductor devices

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat dissipating encapsulant for semiconductor devices, and more particularly to a high heat dissipating encapsulant for high heat dissipation for encapsulating a highly integrated semiconductor device to effectively dissipate heat therein.

The semi-finished semiconductor device, which is completed by repeatedly performing various processes such as epitaxial process, oxidation process, diffusion process, and annealing according to a predetermined design, must be sealed with an encapsulant in a packaging process after performing a final inspection. It is well known that the purpose of encapsulating is to protect the internal semiconductor device from an external environment such as external physical shock or chemical change and to facilitate the mounting of the semiconductor device.

Therefore, the encapsulant for semiconductor devices is based on the moisture absorption rate and the saturated moisture absorption, mainly based on the heat resistance subdivided into moldability and thermal stability, glass transition temperature, thermal expansion, thermal conductivity and thermal shock resistance, etc. Moisture resistance, such as amount and moisture resistance after soldering; Adhesiveness, in particular, with an insulating film or a protective film on a silicon die, a metal lead frame, a die pad or a die surface; Electrical characteristics such as electrical insulation, high frequency characteristics, and chargeability; Mechanical properties subdivided into tensile properties, bending properties, strength, elasticity and / or strain high temperature properties and toughness; Other marking properties, flame retardancy and coloring should be considered.

In particular, excessive heat generation in an encapsulated semiconductor device due to high integration of the semiconductor device may cause problems such as delayed signal transmission of the semiconductor device, generation of cracks due to heat, and destruction by thermal fatigue of the encapsulant itself. Therefore, the heat resistance and the thermal conductivity of the encapsulant are increasingly important, and the development of a superior encapsulant may be an important factor such that it can act as one of the direct factors enabling the commercialization of highly integrated semiconductor devices.

As a sealing agent for this purpose, many commercially available sealing agents have been developed and commercialized. Efforts have been made to develop an encapsulant having superior physical properties. In addition, an epoxy molding compound (EMC) is commercialized. Epoxy Molding Compound) is widely used, and epoxy molding compound is adjusted and used to satisfy various characteristics required as a semiconductor encapsulant by blending various materials.

Until now, epoxy molding compounds for encapsulation of semiconductor devices have been used as epoxy resins that act as binders as base resins, hardeners that react with the epoxy resins to form crosslinks, and reaction times between epoxy resins and hardeners. Adjusting curing accelerator (Accelerator), a filler added to the epoxy resin to adjust the thermal expansion coefficient, thermal conductivity and mechanical strength, etc. for improving the bonding force between the organic material represented by the epoxy resin and the inorganic material represented by the filler Coupling Agent, Release Agent and Other Low Stress Additive for Imparting Mold Release from Mold, Flame Retardant, Colorant, Ion Catcher and // Or modifying agents such as adhesion promoters. Epoxy molding compounds currently commercially available include 5 to 20 weight percent epoxy resin, less than 2 weight percent hardener, less than 1 weight percent curing accelerator, 60 to 85 weight percent filler, and less than 1 weight percent binder. Less than 5% by weight low stress agent, less than 1% by weight release agent, less than 1% by weight flame retardant aid, less than 1% by weight colorant, less than 1% by weight ion trapping agent and less than 1% by weight adhesive agent In particular, as a filler, fused silica is used.

However, conventional epoxy molding compounds filled with molten silica as described above have a direct effect on the thermal conductivity, and also because the thermal conductivity of the molten silica itself, which occupies most of the encapsulating agent, is considerably low, so that conventional fillers using such conventional fillers Epoxy molding compound has a problem that there is a limit to high heat dissipation.

Particularly, in the case of high-density semiconductor devices such as 16M DRAM, which have been mass-produced and commercialized in recent years, heat generated inside the sealed semiconductor device is sufficiently released to the outside, and cracks generated by the heat and the sealing agent itself There was a problem that problems such as destruction due to thermal fatigue occur frequently.

Therefore, the development of a new sealing agent for semiconductor devices having high heat dissipation is urgently required.

An object of the present invention is to provide a high heat dissipating encapsulant for encapsulating a semiconductor device which is highly integrated to generate a large amount of heat.

High heat-sealing encapsulant for semiconductor devices according to the present invention for achieving the above object, 7 to 12% by weight of epoxy resin, 3 to 7% by weight of the curing agent, 0.01 to 0.2% by weight of the curing accelerator, fillers 77.8 to 89.69 Wt% aluminum nitride (AlN), 0.1 to 1.0 wt% binder, 0.1 to 1.0 wt% release agent and 0.1 to 1.0 wt% modifier.

As the aluminum nitride, preferably, a spherical aluminum nitride having a particle diameter of 10 μm or more may be used.

In the above, preferably, a silane-based and zirconia-based binder may be used.

The modifier may be selected from the group consisting of a low stress agent, a flame retardant aid, a colorant, an ion trapping agent or an adhesive agent or a mixture of two or more thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The heat dissipating encapsulant for semiconductor devices according to the present invention is characterized in that aluminum nitride is used as a filler, unlike ordinary epoxy molding compound filled with silica, and 7 to 12% by weight of epoxy resin, 3 to 7 Weight percent curing agent, 0.01 to 0.2 weight percent curing accelerator, 77.8 to 89.69 weight percent aluminum nitride as filler, 0.1 to 1.0 weight percent binder, 0.1 to 1.0 weight percent release agent and 0.1 to 1.0 weight percent modifier It is made to include.

In the epoxy resin as a base resin forming the base of the semiconductor encapsulant as a binder, a conventional epoxy resin can be used, satisfying the various properties required as the encapsulant, low cost, electrical insulation It is excellent in use, and has a low shrinkage rate compared to other thermosetting resins, and is widely used because it exhibits evenly excellent properties in adhesion, heat resistance, moisture resistance, and chemical resistance. Such epoxy resins are well known to those skilled in the art so that they can be easily understood, and particularly in the present invention, preferably novolak-based epoxy resins can be used. The epoxy resin is preferably used in the range of 7 to 12% by weight, when the epoxy resin is used in less than 7% by weight, the problem that the proper molding is difficult due to the poor adhesion and flowability during molding If the epoxy resin exceeds 12% by weight, the content of the resin, which is a poor conductor in heat, and the content of the filler for the thermal conductivity is relatively low, so the problem of deterioration of the thermal conductivity is particularly exceeded. That is not desirable.

The curing agent may increase crosslinking density by increasing crosslinking density by reacting with the epoxy resin to increase crosslinking density, and the chemical properties thereof may be similar to epoxy resins. The curing agent is preferably used in the range of 3 to 7% by weight, and when the curing agent is used at less than 3% by weight, it does not significantly affect the increase in the crosslinking density and thus does not significantly increase the adhesiveness and heat resistance. In this case, when the curing agent exceeds 7% by weight, the crosslinking density increases so much that it tends to be brittle mechanically, and in particular, since the moisture absorption amount increases in proportion to the increased crosslinking point, the cracks in the increased soldering process ( Problems such as cracks may occur.

Preferably, as the curing agent, a phenol novolak curing agent may be used, and such a phenol novolak curing agent is produced by domestic and foreign leading manufacturers and is provided commercially, and to those skilled in the art It can be understood to be known to the extent that it can be easily understood. However, it can be understood that other commercially available hardeners such as Xylok type hardeners can be used in addition to the phenol novolac hardener as the hardener.

The curing accelerator is used to prevent deformation during release by promoting crosslinking reaction between the epoxy resin as the base resin and the curing agent to enable rapid curing, and is easily understood by those skilled in the art. Obviously, amines such as imidazole or phosphorus compounds such as TPP can be used. The curing accelerator may be used in an amount of about 0.01 to 0.2% by weight, and those skilled in the art may determine the use of an appropriate curing accelerator in consideration of workability of molds and mold releases, determination of curing rate, flowability, and the like. When the amount is less than the weight%, it is difficult to expect the effect of increasing the curing rate, and when it exceeds 0.2 weight%, problems such as poor mold release and mold contamination may occur.

As a filler considered as a main element for showing high heat dissipation in the high heat dissipating encapsulant for semiconductor devices according to the present invention, aluminum nitride is used, and the coefficient of thermal expansion is the same as or similar to that of silica used as a filler in the conventional encapsulant. It is added to epoxy resin and used to control thermal conductivity and mechanical strength. In particular, the aluminum nitride has a high thermal conductivity properties that can be used in the engine ignition site for automobiles, and the aluminum nitride material itself is also known to be commercially available. The aluminum nitride may be filled with a high content of 77.8 to 89.69% by weight, and when aluminum nitride is filled to less than 77.8% by weight, thermal conductivity and strength may be reduced, and aluminum nitride may be 89.69% by weight. If it exceeds, the content of the filler may be too high to lower the fluidity (flow), thereby reducing the workability in the mold, the defects will occur frequently. Preferably, as the aluminum nitride, spherical aluminum nitride having a particle diameter of 10 μm or more may be used. When the particle diameter is less than 10 μm, the effect of increasing thermal conductivity may be further improved, but the flow may increase due to the increase in the specific surface area of the particle. There may be a problem that the molding process may be impossible by reducing the property, and preferably a spherical one may be used, which may be understood to increase flowability, that is, flowability.

The binder is used to improve the bonding strength between the organic material represented by the epoxy resin and the inorganic material represented by the filler, it can also be understood to play the same or similar role as the conventional binder. The binder may be used in the range of 0.1 to 1.0% by weight, when the binder is used in less than 0.1% by weight, insufficient bonding may occur between the epoxy resin and aluminum nitride, and the binder may be 1.0% by weight. When exceeded, workability, such as a decrease in mold release property, may be caused, and a problem may occur in which long-term water resistance and a decrease in binding force may occur due to self-reaction of the binder.

As the binder, silane-based and zirconia-based binders may be preferably used, and for example, a binder such as KZ 55H (trade name of Kenreact company) may be used.

In addition to the above components, a mold release agent and various kinds of modifiers may be used to facilitate mold release from the mold and increase productivity, and such mold release agents or modifiers may be easily understood by those skilled in the art. It is obvious.

In particular, the modifier may be selected from the group consisting of low stress agents, flame retardant aids, colorants, ion trapping agents or adhesion imparting agents or mixtures of two or more thereof, and these low stress agents, flame retardant aids, colorants, ion trapping agents or Adhesive force-imparting agents and the like can also be easily understood by those skilled in the art, and it is obvious that they can be purchased and used commercially.

Example

97.3g of novolac epoxy resin, 51.5g of phenol novolak curing agent, 55g of Kage Act brand name, 1.1g of aluminum nitride as filler, 83g of aluminum nitride, 5g of binder, 5g of release agent, and 2g of modifier 2g An encapsulant was prepared, and the physical properties such as thermal conductivity, thermal expansion coefficient, dielectric constant, scattering coefficient and gel time were measured and shown in Table 1. Here, the thermal conductivity test conditions are made of disk-shaped specimens (40ψ * 2mm, 4mm) and inserted into a copper rod of HVS-40-300SDS to test the thermal conductivity of the disk-shaped specimens to be tested through the thermal conductivity of the known copper The dielectric constant and the scattering coefficient were also measured using a LF IMPEDANCE ANALYSER (model name: HP4192A) at room temperature by making disk shaped specimens (2ψV * 4mm). The coefficient of thermal expansion was measured in the form of a rod according to ASTM test conditions and measured by ANTER Linear Dilatometer, and gel time was measured by the time required for curing according to the conventional method. Got it.

[Calculation Formula 1]

Physical Properties of High Thermal Sealant for Semiconductor Devices According to the Present Invention Test Items Test result Test equipment Thermal conductivity 13.472 W / mK HVS-40-300SDS Coefficient of thermal expansion (α ₁ ) 17.5 / ℃ * 10 ^-6 Dilatometer Coefficient of thermal expansion (α ₂ ) 28.8 / ℃ * 10 ^-6 Dilatometer Dielectric constant 2.02 HP4192LF IMPEDANCE ANALYSER Scattering coefficient 0.02 HP4192LF IMPEDANCE ANALYSER Gel time 35 seconds DSC

Comparative example

Except that 700g was filled with crystalline silica having the highest thermal conductivity among silica as a filler, an encapsulant was prepared using the same composition as in the above example, and thermal conductivity, thermal expansion coefficient, and dielectric constant were also obtained using the same measuring instrument. Physical properties such as, scattering coefficient and gel time were measured and shown in Table 2.

Physical Properties of Conventional Encapsulant Using Silica Test Items Test result Test equipment Thermal conductivity 1.7 W / mK HVS-40-300SDS Coefficient of thermal expansion (α ₁ ) 35.5 / ℃ * 10 ^-6 Dilatometer Coefficient of thermal expansion (α ₂ ) 55.8 / ℃ * 10 ^-6 Dilatometer Dielectric constant 5.0 HP4192LF IMPEDANCE ANALYSER Scattering coefficient 0.02 HP4192LF IMPEDANCE ANALYSER Gel time 15 seconds DSC

In contrast with the physical properties of Tables 1 and 2, the thermal conductivity sealing agent for semiconductor devices according to the present invention has a thermal conductivity improved by at least 8 times and a thermal expansion coefficient at least 1/2 lower than that of a conventional sealing agent using silica. can confirm.

Therefore, according to the present invention, there is an effect of providing a high heat dissipating encapsulant that can be used to seal a highly integrated, high heat generating semiconductor device.

In addition, according to the present invention has an effect of providing a high heat-dissipating encapsulant improved crack resistance by the signal transmission rate and thermal stress.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (5)

7-12 wt% epoxy resin, 3-7 wt% curing agent, 0.01-0.2 wt% curing accelerator, 77.8-89.69 wt% aluminum nitride as filler, 0.1-1.0 wt% binder, 0.1-1.0 wt% A high heat dissipating encapsulant for a semiconductor device, comprising:% release agent and 0.1 to 1.0 wt% modifier. The method of claim 1, The high heat-sealing encapsulant for the semiconductor device, characterized in that aluminum nitride having a particle diameter of 10 μm or more is used as the aluminum nitride. The method of claim 1, A spherical aluminum nitride is used as the aluminum nitride. The method of claim 1, The heat dissipating encapsulant for the semiconductor device, characterized in that the binder is a silane-based and zirconia-based binder. The method according to any one of claims 1 to 4, Wherein the modifier is selected from the group consisting of low stress agents, flame retardant aids, colorants, ion trapping agents or adhesion imparting agents or mixtures of two or more thereof.