JP6787285B2 - Semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device including a semiconductor element.

There are various forms of semiconductor devices (for example, power modules or power cards) equipped with semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors). For example, lead frames, solder layers as bonding materials, and semiconductor elements. Examples thereof include those having a structure in which a laminate containing the above is housed in a case and a sealing resin body is further formed in the case. Further, there is also known a semiconductor device in which two lead frames are present at the top and bottom, and a laminate in which a semiconductor element is arranged between them with a bonding material is integrated with a sealing resin. The front surface and the back surface of this semiconductor device are electrically and thermally conductively bonded to each lead frame via a solder layer.

In a semiconductor device such as a power card, if the sealing resin body and the lead frame are peeled off, the function of the semiconductor element may be stopped due to cracking of solder in the semiconductor device or mixing of foreign matter. Therefore, a primer is used to improve the adhesiveness between the sealing resin body and the lead frame.

Patent Document 1 discloses a primer composition for adhering an epoxy resin molding material for semiconductor encapsulation, which contains an alkoxysilyl group-containing polyamide-imide resin represented by a predetermined formula. According to Patent Document 1, the primer composition is cured with excellent adhesiveness between an epoxy resin molding material for encapsulating a semiconductor and a semiconductor element sealed therein, and also having excellent properties such as heat resistance and water resistance. It is stated that the film can be applied by heat curing at low temperature for a short time.

Patent Document 2 discloses an electrical component using a primer layer containing a polyimide polymer having a structure represented by a predetermined formula. According to Patent Document 2, the primer layer can exhibit a high affinity with a sealing resin body containing an epoxy resin and / or a maleimide resin, and therefore, the inside of the sealing resin body in a wide temperature range. It is stated that peeling can be suppressed.

Japanese Unexamined Patent Publication No. 2006-241414 Japanese Unexamined Patent Publication No. 2016-15372

In recent years, in-vehicle semiconductor devices, miniaturization and SiC of elements have been proposed with the aim of improving performance, but there are concerns about an increase in heat generation temperature due to miniaturization and an increase in generated stress due to SiC. Specifically, since the SiC element has a larger coefficient of linear expansion than the conventional Si element and the operating temperature is higher than that of the SiC element (for example, over 240 ° C.), the generated stress tends to be large, and the generation stress tends to be large. , Highly likely to be exposed to high temperature environments.

However, although the polyimide disclosed in the above-mentioned patent document is presumed to be able to cope with an increase in heat generation temperature from the viewpoint of heat resistance, it may not be able to sufficiently cope with an increase in heat generation stress from the viewpoint of adhesive strength. There is sex. Specifically, since the polyimide disclosed in the above-mentioned patent document does not have sufficient adhesive strength, peeling may occur between the sealing resin body and the lead frame when the generated stress of the semiconductor element increases. There is. Therefore, it is desired to develop a semiconductor device in which peeling between members is suppressed even in a high temperature environment.

Therefore, an object of the present invention is to provide a semiconductor device having excellent durability even in a high temperature environment.

The present inventors have found that the adhesive strength between the sealing resin body and the lead frame can be improved by using a primer layer containing a polyimide polymer whose value X calculated by a predetermined formula is in a predetermined range. The headline came up with the present invention.

Therefore, one form of the present invention is
A semiconductor device including a semiconductor element, a lead frame, a sealing resin body, and a primer layer arranged between the lead frame and the sealing resin body.
The primer layer contains a polyimide polymer which is an imide of polyamic acid which is a polymer of acid anhydride and diamine.
A semiconductor device in which the value X calculated by the following formula (1) is 0.182 or more and 0.213 or less.
X = (α _a + α _b ) / (V _a + V _b ) Equation (1)
[In formula (1), α _a is the polarizability of the acid anhydride, α _b is the polarizability of the diamine, V _a is the van der Waals volume of the acid anhydride, and V _b is the van der Waals of the diamine. Waals volume. ].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a semiconductor device having excellent durability even in a high temperature environment.

It is a schematic sectional drawing for showing the semiconductor device which concerns on this embodiment. It is a schematic sectional drawing for showing the semiconductor device which concerns on this embodiment. It is schematic cross-sectional view for demonstrating the process example of manufacturing the semiconductor device which concerns on this Embodiment.

The present embodiment relates to a semiconductor device including a semiconductor element, a lead frame, a sealing resin body, and a primer layer arranged between the lead frame and the sealing resin body. In the present embodiment, the primer layer contains a polyimide polymer which is an imide of polyamic acid which is a polymer of acid anhydride and diamine. Further, in the present embodiment, the value X calculated by the above formula (1) is 0.182 or more and 0.213 or less.

In the semiconductor device according to the present embodiment, the polyimide polymer has heat resistance and can firmly bond the sealing resin body and the lead frame. Therefore, the semiconductor device according to the present embodiment can effectively suppress the peeling of the sealing resin body and the lead frame even under high temperature conditions, and is excellent in durability under high temperature conditions.

Hereinafter, the configuration of the semiconductor device according to the present embodiment will be described.

The lead frame is mainly composed of a metal material, and examples of the metal material include aluminum, copper, and alloys thereof. The lead frame may be formed by applying a nickel plating layer around a metal core such as aluminum or an alloy thereof, or copper or an alloy thereof. Further, a gold plating layer may be formed on the surface of the nickel plating layer.

Examples of the semiconductor element include, but are not limited to, a power element including a SiC substrate and the like.

The semiconductor element is arranged on the lead frame via a bonding material. The solder layer as the bonding material is not particularly limited, and may be, for example, either Pb-based solder or Pb-free solder. The solder layer is Pb-free, such as Sn-Ag solder, Sn-Cu solder, Sn-Ag-Cu solder, Sn-Zn solder, and Sn-Sb solder, from the viewpoint of reducing the impact on the environment. Solder is preferred.

The material (sealing resin) of the sealing resin body is not particularly limited, and examples thereof include a thermosetting resin and a thermoplastic resin. Examples of the thermosetting resin include epoxy resins, and examples of the thermoplastic resin include polyamide-imide. The epoxy resin is a thermosetting synthetic resin, and contains, for example, an epoxy compound having a reactive epoxy group at its terminal and a curing agent. Specific examples of the epoxy resin include bisphenol A type epoxy resin produced by a condensation reaction of bisphenol A and epichlorohydrin, novolac type epoxy resin, trisphenol methane type epoxy resin, bisphenol F type epoxy resin, and polyfunctional epoxy. Examples thereof include resins, flexible epoxy resins, biphenyl type epoxy resins, polymer type epoxy resins and glycidyl ester type epoxy resins, which may be used alone or in combination of two or more. Good. Examples of the thermosetting resin include engineering plastics such as polyphenylene sulfide and polybutylene terephthalate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and the like, in addition to polyamide-imide.

Further, the sealing resin may contain an inorganic filler such as silica, alumina, boron nitride, silicon nitride, silicon carbide or magnesium oxide for the purpose of improving thermal conductivity and thermal expansion.

The primer layer contains a polyimide polymer which is an imide of polyamic acid which is a polymer of acid anhydride and diamine. Further, for acid anhydride and diamine, the value X calculated by the formula (1) is 0.182 or more and 0.213 or less.
X = (α _a + α _b ) / (V _a + V _b ) Equation (1)
[In formula (1), α _a is the polarizability of the acid anhydride, α _b is the polarizability of the diamine, V _a is the van der Waals volume of the acid anhydride, and V _b is the van der Waals of the diamine. Waals volume. ].

The value X is a parameter representing the charge bias of the polyimide polymer, and the larger the value X, the larger the intermolecular force caused by the charge bias of the polyimide polymer, and as a result, the sealing resin of the polyimide polymer. Increases adhesive strength to the body. When the value X is 0.182 or more, the adhesive strength between the polyimide polymer and the sealing resin body can be effectively improved. Further, the value X is specified to be 0.213 or less, which is selected as a range that can be produced in the polyimide polymer.

For the polarizability of the acid anhydride or diamine, publicly available values can be used, for example, in "New Edition Latest Polyimide-Basics and Applications-, NTS, 102-128 (2010)". Are listed. Moreover, the polarizability of acid anhydride or diamine can be approximately obtained from the Lorentz-Lorenz equation.

For the van der Waals volume of acid anhydride or diamine, publicly available values can be used, for example, "New Edition Latest Polyimide-Basics and Applications-, NTS, 102-128 (2010). "It is described in. In addition, the van der Waals volume of acid anhydride or diamine can be calculated by using each van der Waals radius for the molecular structure optimized by the density functional theory.

The polyamic acid can be obtained by polymerizing an acid anhydride and a diamine. Specifically, an acid anhydride, a diamine and a solvent are mixed to prepare a mixed solution, and the acid anhydride and the diamine are reacted in the mixed solution to obtain a primer solution containing a polyamic acid. The content of the polyamic acid in the primer solution is preferably 2 to 50% by mass, more preferably 10 to 25% by mass. Further, the blending ratio of the acid anhydride and the diamine can be appropriately adjusted in consideration of the equivalent ratio of the functional groups of both.

The acid anhydride preferably has a structure represented by the following formula (2).

［式（２）中、Ｒ_１は、カルボニル基（−ＣＯ−）、エステル基（−ＣＯＯ−）、カーボネート基（−ＯＣＯＯ−）、又はチオエーテル基（−Ｓ−）である。］

[In the formula (2), R ₁ is a carbonyl group (-CO-), an ester group (-COO-), a carbonate group (-OCOO-), or a thioether group (-S-). ]

The diamine preferably has a structure represented by the following formula (3).

［式（３）中、Ｒ_２は、炭素数１〜３のアルキレン基、エーテル基（−Ｏ−）、カルボニル基（−ＣＯ−）、エステル基（−ＣＯＯ−）、カーボネート基（−ＯＣＯＯ−）、又はチオエーテル基（−Ｓ−）である。］

[In the formula (3), R ₂ has an alkylene group having 1 to 3 carbon atoms, an ether group (-O-), a carbonyl group (-CO-), an ester group (-COO-), and a carbonate group (-OCOO-). ), Or a thioether group (-S-). ]

The primer layer can be formed by applying and heating a primer solution containing a polyamic acid which is a polymer of an acid anhydride and a diamine. By this heating, dehydration and ring closure reaction (imidization) of the polyamic acid occur, and a polyimide polymer can be formed.

The primer solution may contain a solvent, additives and the like as appropriate in addition to the acid anhydride and diamine. Examples of the solvent include N-methyl-pyrrolidone (NMP).

The polyimide polymer preferably contains a structure represented by the following formula (A).

［式（Ａ）中、Ｒ_１は、カルボニル基（−ＣＯ−）、エステル基（−ＣＯＯ−）、カーボネート基（−ＯＣＯＯ−）、又はチオエーテル基（−Ｓ−）であり、Ｒ_２は、炭素数１〜３のアルキレン基、エーテル基（−Ｏ−）、カルボニル基（−ＣＯ−）、エステル基（−ＣＯＯ−）、カーボネート基（−ＯＣＯＯ−）、又はチオエーテル基（−Ｓ−）である。］

[In the formula (A), R ₁ is a carbonyl group (-CO-), an ester group (-COO-), a carbonate group (-OCOO-), or a thioether group (-S-), and R ₂ is With an alkylene group having 1 to 3 carbon atoms, an ether group (-O-), a carbonyl group (-CO-), an ester group (-COO-), a carbonate group (-OCOO-), or a thioether group (-S-). is there. ]

With respect to R ₂ of formula (A), the alkylene group is, for example, a methylene group (-CH _2- ) or an ethylene group (-CH ₂ CH _2- ). Further, the alkylene group may be linear or branched chain.

In the formula (A), n is, for example, an integer of 1 to 100,000.

The polyimide polymer preferably contains a structure represented by the above formula (A), and may partially contain a structure other than the above formula (A) within a range in which the effect of the present invention is substantially exhibited.

Hereinafter, the configuration of the semiconductor device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining a configuration example of the semiconductor device of the present embodiment. In FIG. 1, the semiconductor device 10 includes a lead frame 1 and a semiconductor element 2. In FIG. 1, a semiconductor element 2 is arranged on a lead frame 1 via a solder layer 3. The primer layer 4 is arranged so as to cover the laminate of the lead frame 1, the semiconductor element 2, and the solder layer 3. More specifically, the region where the solder layer 3 is not adhered on the surface of the lead frame 1 on the side where the semiconductor element 2 is arranged, and the surface of the solder layer 3 where the lead frame 1 and the semiconductor element 2 are adhered. The non-existing region and the region of the surface of the semiconductor element 2 to which the solder layer 3 is not adhered are coated with the primer layer 4. Further, the sealing resin body 5 is arranged on the primer layer 4 so as to cover the laminated body via the primer layer 4. In the figure, wires and the like connected to the semiconductor element 2 are omitted.

Further, the semiconductor device according to the present embodiment may include a plurality of semiconductor devices. Further, the semiconductor device according to the present embodiment may include two lead frames. FIG. 2 is a schematic cross-sectional view for explaining a configuration example of the semiconductor device of the present embodiment. In FIG. 2, the semiconductor device 100 includes two semiconductor elements, that is, a first semiconductor element 102a and a second semiconductor element 102b. In the semiconductor device 100, two semiconductor elements are mounted in parallel. Further, the semiconductor device 100 includes two lead frames, that is, a first lead frame 101a and a second lead frame 101b. In FIG. 2, a first semiconductor element 102a and a second semiconductor element 102b are arranged on the first lead frame 101a via a first solder layer (103a, 103b), respectively. Further, on the first semiconductor element 102a and the second semiconductor element 102b, the first metal block 106a and the second metal block 106b are arranged via the second solder layers (107a, 107b), respectively. ing. Further, on the first metal block 106a and the second metal block 106b, a second lead frame 101b is arranged via a third solder layer (108a, 108b), respectively. The primer layer 104 covers a laminate including a lead frame (101a, 101b), a solder layer (103a, 103b, 107a, 107b, 108a, 108b), a semiconductor element (102a, 102b), and a metal block (106a, 106b). It is arranged to do. Further, the sealing resin body 105 is arranged on the primer layer 104 so as to cover the laminated body via the primer layer 104. The metal block is preferably made of copper.

(Manufacturing example of semiconductor device)
FIG. 3 is a schematic cross-sectional view for explaining an example of a method for manufacturing the semiconductor device of the present embodiment.

First, as shown in FIG. 3A, the semiconductor element 2 is arranged on the lead frame 1 via the solder layer 3, and the intermediate body 10'of the semiconductor device is manufactured.

Next, as shown in FIG. 3B, a primer solution is applied to the surface of the intermediate 10'of the semiconductor device, and heat treatment is performed to cause an imidization reaction to form the primer layer 4. Examples of the method for applying the primer solution include a spin coating method, a spray method, and a dipping method.

Next, as shown in FIG. 3C, the sealing resin is placed on the primer layer 4 and cured to form the sealing resin body 5. As a result, the semiconductor device 10 is manufactured.

The semiconductor device of the present embodiment is not particularly limited, but can be used, for example, as a semiconductor device (power card) used in a power control unit for a hybrid vehicle.

Hereinafter, examples of the present invention will be described. The present invention is not limited to the description of the following examples.

(Example)
<Preparation of laminate>
Primer solutions A1 to A4 and B1 to B5 containing polyamic acids corresponding to the polyimide polymers of the following formulas (A1) to (A4) and (B1) to (B5) were prepared. Each primer solution was obtained by adding acid anhydride and diamine as raw materials in equal molar amounts to the N-methylpyrrolidone solution and stirring overnight. The values X of the polyimide polymers of the formulas (A1) to (A4) and (B1) to (B5) are shown in Table 1 below. Further, the polarizabilities (α _a , α _b ) and fans of acid anhydrides and diamines for producing polyamic acids corresponding to the polyimide polymers of the formulas (A1) to (A4) and (B1) to (B5). The Delwars volume (V _a , V _b ) is also shown in Table 1. These values were used with reference to "New Edition Latest Polyimide-Basics and Applications-, NTS, 102-128 (2010)".

Primer solutions A1 to A4 and B1 to B5 were each applied by spin coating to a lead frame plated with electroless nickel phosphorus. The film thickness of the primer solution after coating was about 1 μm. Then, after a drying treatment at 120 ° C. for 1 hour, a curing treatment (imidization) was performed at 210 ° C. for 1 hour to form a primer layer. Next, a sealing resin body (epoxy resin) was formed on the primer layer in the shape of a pudding cup to form laminates A1 to A4 and B1 to B5.

<Evaluation test>
The prepared laminates A1 to A4 and B1 to B5 were placed in a high temperature environment of 250 ° C. Then, a tool was applied to the sealing resin body portion, and the pressure when the sealing resin body was detached from the lead frame was measured as the adhesive strength (MPa) between the primer layer and the sealing resin body. The results are shown in Table 1. As the measuring device, a universal bond tester SERIES4000 manufactured by Nordson Advanced Technology Co., Ltd. was used.

As is clear from Table 1, it can be seen that the higher the value X of the polyimide polymer contained in the primer layer, the higher the adhesive strength between the primer layer and the sealing resin body.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope of the gist of the present invention, they are not limited to these embodiments. Is included in the present invention.

1 lead frame,
2 Semiconductor element 3 Solder layer 4 Primer layer 5 Encapsulating resin body 10 Semiconductor device 10'Intermediate body of semiconductor device,
101a First lead frame 101b Second lead frame 102a First semiconductor element 102b Second semiconductor element 103a, 103b First solder layer 104 Primer layer 105 Encapsulating resin body 106a, 106b Metal blocks 107a, 107b Second Solder layers 108a, 108b Third solder layer 100 Semiconductor device

Claims (1)

A semiconductor device including a semiconductor element, a lead frame, a sealing resin body, and a primer layer arranged between the lead frame and the sealing resin body.
The primer layer contains a polyimide polymer which is an imide of polyamic acid which is a polymer of acid anhydride and diamine.
A semiconductor device in which the value X calculated by the following formula (1) is 0.182 or more and 0.213 or less.
X = (α _a + α _b ) / (V _a + V _b ) Equation (1)
[In formula (1), α _a is the polarizability of the acid anhydride, α _b is the polarizability of the diamine, V _a is the van der Waals volume of the acid anhydride, and V _b is the van der Waals of the diamine. Waals volume. ].

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