JP7132298B2 - Substrate for semiconductor device, method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device substrate having a die pad and/or leads on a mother die, and a semiconductor device manufacturing method using the semiconductor device substrate.

A substrate for a semiconductor device is prepared on which a metal portion to be used as a die pad and leads is formed, a semiconductor element is mounted on the substrate for a semiconductor device, and after processing such as wiring, the surface side of the metal portion having the semiconductor element and the wiring is removed. A semiconductor device that is sealed with a sealing resin and has a structure in which the metal part is partially exposed at the bottom can be reduced in height to save space, and is being used in the field of small semiconductor devices. . Such semiconductor devices are mainly formed by plating (electroforming) a desired number of metal portions, which will become die pads and leads, on a matrix, and forming the desired number of semiconductor devices. After sealing the surface side of the semiconductor device with a sealing resin, only the matrix is removed, and a large number of integrated semiconductor devices are individually cut into pieces. is disclosed in Patent Document 1.

JP 2004-214265 A

In recent years, there has been a demand for further miniaturization of semiconductor devices, and in order to meet this demand, it is necessary to miniaturize metal portions that serve as die pads and leads. However, miniaturizing the metal parts that become the die pads and leads reduces the contact area between the metal parts and the encapsulation resin, weakening the adhesion force, and there is a risk that the metal parts will be misaligned or missing when the matrix is removed. There is

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide a substrate for a semiconductor device capable of preventing the occurrence of misalignment and voids in metal portions, and a method for manufacturing a semiconductor device using this substrate for a semiconductor device. to do.

The present invention is a substrate for a semiconductor device in which a metal part that becomes the lead 3 or the die pad 4 exposed on the bottom surface of the device is formed on a mother mold 20, the mother mold 20 including a first base material 20a serving as the outermost layer. A plurality of substrates are laminated, and the adhesiveness between the substrates is weaker than the adhesiveness of the surface of the first substrate 20a on which the metal part is formed. This can be achieved by setting the adhesion between the base materials weaker than the surface of the first base material 20a on which the metal portion is formed. Further, the mother die 20 is characterized in that a first base material 20a and a second base material 20b are laminated, and the first base material 20a is plated on the second base material 20b. Also, the second base material 20b is made of stainless steel, and the first base material 20a is made of nickel.

The present invention also relates to a method of manufacturing a substrate for a semiconductor device in which a metal part that becomes the lead 3 or the die pad 4 exposed on the bottom surface of the device is formed on the mother mold 20, and includes the first base material 20a that becomes the outermost layer. forming a matrix 20 by laminating a plurality of base materials; forming a resist pattern layer 25 for forming a metal part on the surface of the first base material 20a of the matrix 20; and a step of removing the resist pattern layer 25 on the surface of the first base material 20a exposed from the substrate. Further, the matrix 20 is characterized in that the first base material 20a is laminated on the second base material 20b made of stainless steel by nickel plating.

Further, according to the present invention, the semiconductor element 2 and the lead 3 connected to the semiconductor element 2 or the metal part that becomes the die pad 4 on which the semiconductor element 2 is mounted are sealed with a resin, and the metal part is exposed on the bottom surface. A method for manufacturing a semiconductor device, comprising a step of forming a matrix 20 by laminating a plurality of substrates including a first substrate 20a serving as an outermost layer; a step of forming a resist pattern layer 25 for forming a portion; a step of forming a metal portion on the surface of the first base material 20a exposed from the resist pattern layer 25; a step of removing the resist pattern layer 25; A step of mounting the semiconductor element 2 on the part and electrically connecting the semiconductor element 2 and the metal part, and a process of sealing the semiconductor element 2 and the metal part with resin to form a resin sealing body 7 and a step of removing the matrix 20 from the resin sealing body 7, and in the step of removing the matrix 20, after removing the base material excluding the first base material 20a on which the metal part is formed, It is characterized by removing the first base material 20a. Further, the matrix 20 is formed by laminating the first base material 20a by nickel plating on the second base material 20b made of stainless steel, and the second base material 20b is peeled off.

According to the present invention, by using a semiconductor device substrate in which a metal part serving as a lead or a die pad is formed on a master mold in which a plurality of base materials including a first base material serving as the outermost layer are laminated, a production process can be performed. Thus, a semiconductor device with excellent performance and reliability can be provided.

1 is a cross-sectional view of a semiconductor device substrate according to a first embodiment of the present invention; FIG. 1A and 1B are a sectional view and a perspective view of a semiconductor device according to a first embodiment of the present invention; FIG. FIG. 4 is a diagram for explaining the method of manufacturing the semiconductor device substrate according to the first embodiment of the present invention; FIG. 4 is a diagram for explaining the method of manufacturing the semiconductor device substrate according to the first embodiment of the present invention; It is a figure for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment of this invention. FIG. 4 is a cross-sectional view of a semiconductor device substrate according to another example of the first embodiment of the present invention;

(First Embodiment) FIGS. 1 to 5 show a semiconductor device substrate and a semiconductor device according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a semiconductor device substrate according to this embodiment. 2A is a cross-sectional view of the semiconductor device according to this embodiment, and FIG. 2B is a perspective view of the semiconductor device according to this embodiment.

A substrate 10 for a semiconductor device is obtained by forming a metal portion that will become the lead 3 and the die pad 4 on a mother mold 20 . The semiconductor device 1 is a leadless surface mount type manufactured using this semiconductor device substrate 10, and includes a semiconductor element 2, a die pad 4 on which the semiconductor element 2 is mounted, and a semiconductor element 2 surrounding the semiconductor element 2. and wires 6 for electrically connecting the leads 3 to the electrodes 5 formed on the upper surface of the semiconductor element 2. These semiconductor element 2, leads 3, die pad 4 and wires 6 is sealed with a resin such as epoxy resin to form a block-shaped resin sealing body 7 as a whole, and the die pad 4 and the leads 3 are exposed on the bottom side. In this embodiment, as shown in FIGS. 1 and 2, one semiconductor element 2, six (plural) leads 3, and one die pad 4 are provided and sealed with resin. A configuration without the die pad 4 may be used, in which case the semiconductor element 2 and the leads 3 are connected by flip-chip bonding or the like.

The matrix 20 is configured by laminating a plurality of base materials including a first base material 20a serving as the outermost layer, and as shown in FIG. It will be. The first base material 20a and the second base material 20b are made of a metal such as stainless steel, aluminum, nickel, or copper, and the first base material 20a and the second base material 20b are made of the same metal. , or may be composed of different metals. As the first base material 20a, it is preferable to use a base material on which the first metal layer 12 formed on the surface is difficult to diffuse. Here, the configuration of the matrix 20 that can prevent the lead 3 and the die pad 4 from being dislocated or missing in the matrix removing process in the manufacturing method of the semiconductor device to be described later, particularly in the case of removing the matrix 20 by peeling, will be described. The first base material 20a is preferably formed thinner than the second base material 20b. Specifically, the thickness of the first base material 20a is preferably 10 to 30 μm, and the thickness of the second base material 20b is preferably 100 to 500 μm. Also, the first base material 20a is preferably made of a softer material than the second base material 20b. For example, the second base material 20b may be made of stainless steel and the first base material 20a may be made of nickel, or the second base material 20b may be made of nickel and the first base material 20a may be made of copper. Moreover, it is preferable to form the first base material 20a after applying a peeling treatment to the surface of the second base material 20b. Formation of an oxide film, an organic film, or the like can be cited as the peeling treatment. Moreover, it is preferable to bond the first base material 20a and the second base material 20b via a resin such as a resist or an adhesive. In this case, the two-dimensional or three-dimensional curved warp of the first base material 20a and the second base material 20b is offset by joining the convex arc surfaces or the concave arc surfaces facing each other, and the matrix 20 is formed. Since they can be formed flat, the flatness of the leads 3 and die pads 4 formed on the matrix 20 can be improved, and the reliability of the semiconductor device can be improved. When the first base material 20a and the second base material 20b are bonded via a resin such as a resist or an adhesive, the method for removing the matrix 20 may be removal by peeling off or removal by dissolution using a treatment liquid. However, when the first base material 20a and the second base material 20b are bonded via a resist, it is difficult to separate and remove the second base material 20b from the first base material 20a. And/or semi-exposure may be performed after forming a resist on the surface of the second base material 20b. As described above, the matrix 20 may have the above-described configuration, but the functions required of the first base material 20a and the second base material 20b are the metal parts forming the leads 3 and the die pad 4. The first base material 20a preferably has high strength and flexibility, and the second base material 20b, on which the first base material 20a is laminated, preferably has flexibility and stiffness.

The lead 3 and the die pad 4 are constructed by laminating a single layer or a plurality of layers. It is a thing. The first metal layer 12 is made of a metal such as gold, silver, palladium, tin, solder, or the like, which is excellent in conductivity and solder wettability, and is formed with a thickness of about 0.01 to 1 μm. The second metal layer 14 is made of nickel, copper, an alloy of these metals, or the like, and is formed with a thickness of about 20 to 100 μm. The third metal layer 16 is made of metal such as gold, silver, palladium, and platinum, and is formed with a thickness of about 0.01 to 1 μm. Note that the third metal layer 16 may not be formed on the die pad 4 .

FIG. 3 shows each step of the method for manufacturing the semiconductor device substrate. First, as shown in FIG. 3(a), an alkali type photosensitive resist is applied by thermocompression bonding or the like on a master mold 20 in which a first base material 20a is laminated on a second base material 20b made of stainless steel by nickel plating. After forming a resist layer 21 by laminating by a method, and exposing a pattern film 23 (glass mask) having a predetermined pattern 22 on the resist layer 21 on one surface side of the master mold 20, exposure is performed by irradiating ultraviolet rays. 3(b), a resist pattern layer 25 having a resist body 25a on one side of the mother die 20 is obtained. The resist pattern layer 25 may be formed by direct drawing without using the pattern film 23 (glass mask).

Next, as shown in FIG. 3(c), the lead 3 and the die pad 4 are formed by plating the first substrate 20a on one side of the mother die 20. Then, as shown in FIG.

Specifically, the process of forming the die pad 4 and the leads 3 will be described. First, as shown in FIG. , After performing plating pretreatment (acid immersion, cathodic electrolysis, chemical etching, strike plating, etc.) and stripping treatment, gold is plated to a thickness of 0.05 to 1 μm on the exposed surface to form the first metal layer 12. Form. When a thin layer of gold (first metal layer 12) is plated on the matrix 20 (first base material 20a) as in the present embodiment, the occurrence of poor growth and poor adhesion of gold plating can be prevented in advance. In order to achieve this, the pretreatment for plating is appropriately performed to remove the inert film on the matrix 20 (first base material 20a). Depending on the material and thickness of the metal layer 12), the above pre-plating treatment is appropriately selected or omitted. The peeling process is also the same. When the exposed surface of the matrix 20 is subjected to chemical etching as pre-plating treatment, the exposed surface becomes a rough surface and has a concave shape corresponding to the amount of the chemical etching.

Next, as shown in FIG. 4B, the surface of the first metal layer 12 is plated (electroformed) with nickel to a thickness of 20 to 80 μm to form a second metal layer 14 as a laminate. In this step, by plating (electroforming) the second metal layer 14 so as to exceed the thickness of the resist pattern layer 25, it is possible to form overhangs on the periphery of the upper ends of the die pad 4 and the leads 3. .

Next, as shown in FIG. 4(c), silver is plated to a thickness of 1.0 to 2.5 μm on the surface of the second metal layer 14 in order to improve binding strength during wire bonding, which will be described later. 3. A metal layer 16 is laminated. Thereafter, by removing the resist pattern layer 25, a semiconductor device substrate having the die pad 4 and the leads 3 formed on the matrix 20 is obtained as shown in FIG. 4(d) and FIG. Note that when the second metal layer 14 is made of nickel or a nickel alloy and the third metal layer 16 grown by plating on the second metal layer 14 is made of silver as in the present embodiment, nickel and silver are not compatible with each other. Therefore, the second metal layer 14 is plated with gold, palladium, or the like, or the second metal layer 14 is strike-plated with gold, silver, copper, or the like. Then, the third metal layer 16 is grown by plating, thereby preventing the occurrence of such defects. Also, the third metal layer 16 may be formed not on the entire surface of the second metal layer 14 but on a portion thereof to be wire-bonded.

Next, a method for manufacturing a semiconductor device will be described. FIG. 5 shows each step of a method of manufacturing a semiconductor device using the substrate for a semiconductor device described above. First, as shown in FIG. 5A, a semiconductor element 2 is mounted on a die pad 4 by die bonding, and as shown in FIG. Then, the electrodes 5 on the semiconductor element 2 and the corresponding leads 3 are connected by an ultrasonic bonding device or the like. In such connection, ball bonding is preferably used for the electrode 5 portion, and wedge bonding is preferably used for the lead 3 portion. In this way, the lead 3 has the third metal layer 16 formed at the connection point of the wire 6, and a metal having excellent binding properties between the lead 3 and the wire 6 is used as the third metal layer 16. As a result, the connection force is further improved, and connection errors can be reduced.

Next, as shown in FIG. 5(c), the portion of the mold 20 on which the semiconductor element 2 is mounted is molded with a resin 38 such as a thermosetting epoxy resin to form the resin sealing body 7 on the mold 20. As shown in FIG. Specifically, one surface side of the mother die 20 is attached to a mold (upper mold), and a sealing resin 38 is press-fitted into the mold through a cavity. Thus, a resin sealing body 7 is formed in which a plurality of sets of semiconductor element 2 mounting portions are continuously sealed with the sealing resin 38 . In this case, the mother die 20 itself functions as a lower die during resin molding. If a plurality of mother dies 20 are arranged in parallel during molding and the sealing resin 38 is press-fitted between each mother die 20 and the upper mold through a liner, a large number of resin sealing can be efficiently performed. It is possible to do

Next, as shown in FIG. 5(d), the matrix 20 is removed from the resin sealing body 7. Next, as shown in FIG. As a method for removing the matrix 20, the matrix 20 is peeled off from the resin sealing body 7 to be removed. Specifically, first, the second base material 20b is peeled off from the first base material 20a constituting the matrix 20, and then the first base material 20a is peeled off from the resin sealing body . At this time, the surface of the second base material 20b is subjected to peeling treatment, and then the first base material 20a is layered, thereby facilitating the peeling and removal of the second base material 20b. As another method for removing the matrix 20, the first base material 20a is made of a dissolvable material, and after removing the second base material 20b from the first base material 20a, the resin sealing body 7 is removed. It can be dissolved and removed by dissolving (etching) the first base material 20a using a treatment liquid or the like that does not affect the first base material 20a. By removing the matrix 20 from the resin sealing body 7 in this way, the back surfaces of the plurality of sets of the leads 3 and the die pads 4 are exposed on the bottom surface of the resin sealing body 7 , and the die pads 4 and the leads 3 are exposed on the bottom surface of the resin sealing body 7 . and the bottom surface of the resin sealing body 7 are substantially flush with each other. That is, the first metal layer 12 of the die pad 4 and the leads 3 is exposed substantially flush with the bottom surface of the resin sealing body 7 .

Next, as shown in FIG. 5(e), through a dicing step of cutting the resin sealing body along the cutting line XX for each semiconductor element 2, the individual resin sealing bodies 7, that is, The semiconductor device 1 is completed.

According to such a method of manufacturing a semiconductor device, the master mold 20 is formed in which the adhesion between the first base material 20a and the second base material 20b is weaker than that of the surface of the first base material 20a on the metal part forming side. In the step of removing the master mold 20, the first base material 20a and the second base material 20b are removed step by step so that the first base material 20a is removed after the second base material 20b is removed. By doing so, it is possible to prevent the leads 3 and the die pad 4 from being deformed, displaced, and missing as much as possible when the matrix is removed, as compared with the case of the single-layer matrix. In addition, if the first base material 20a is formed by plating, not only can the first base material 20a be formed thin, but also by adjusting the amount of the brightener added and the current density during plating, the first base material can be thinned. Since the surface roughness of the matrix 20a can be easily set, the flatness of the matrix 20 (first base material 20a) can be improved, and the leads formed on the matrix 20 (first base material 20a) can be improved. Since the flatness of 3 and die pad 4 can be improved, the reliability of the semiconductor device can be improved. Further, if the mold 20 is transported or stored in a state in which only the second base material 20b is removed (a state in which the resin sealing body 7 is formed on the first base material 20a), there is no second base material 20b. Accordingly, transportation and storage are facilitated, and the first base material 20a can serve as a protective layer for preventing oxidation and adhesion of dust to the back surfaces of the leads 3 and the die pad 4. FIG. In peeling and removing the master mold 20, the strength of adhesion between the layers of the metal portion that becomes the lead 3 and the die pad 4, the sealing resin 38, the first base material 20a, and the second base material 20b is as follows: Between the metal portion (first metal layer 12) and the first base material 20a>Between the first base material 20a and the second base material 20b, Between the sealing resin 38 and the first base material 20a>First Between the base material 20a and the second base material 20b, between the metal part and the sealing resin 38>between the metal part (first metal layer 12) and the first base material 20a". . Such conditions can be set by appropriately selecting pre-plating treatment and peeling treatment on the surfaces of the first base material 20a and the second base material 20b.

Moreover, since the first metal layer 12, the second metal layer 14, and the third metal layer 16, which constitute the lead 3 and the die pad 4, are laminated in a continuous plating/electroforming process, the mass productivity is excellent. Since the first metal layer 12 made of a metal with excellent conductivity and solder wettability is exposed from the back surface of each semiconductor device, the mounting process on the mounting board can be performed without subsequent barrel plating or electroless plating. It is also excellent in mass productivity in terms of being able to move to.

In this embodiment, when forming the metal portion (second metal layer 14) that becomes the lead 3 and the die pad 4 shown in FIG. As shown in FIG. 6, the die pad 4 and the leads 3 can be formed with overhangs on their upper edges. Since the die pad 4 and the upper ends of the leads 3 have protrusions in this manner, the encapsulation resin 38 hardens in a state of being bitten in when the encapsulation resin 38 is sealed. Due to the effect (anchor effect), when the mother die 20 is peeled off and removed from the resin encapsulant 7 in the post-process, the die pad 4 and the leads 3 reliably remain on the resin encapsulant 7 side and stick together with the mother die 20. Therefore, it is possible to prevent misalignment and missing. Further, as described above, by forming the matrix 20 to have a laminated structure, it is possible to more effectively prevent the die pad 4 and the leads 3 from being displaced or missing when the matrix 20 is removed, thereby improving the manufacturing yield. The reliability of the semiconductor device itself completed by such a manufacturing method is also improved.

REFERENCE SIGNS LIST 1 semiconductor device 2 semiconductor element 3 lead 4 die pad 5 electrode 6 wire 7 resin sealing body 10 substrate for semiconductor device 12 first metal layer 14 second metal layer 16 third metal layer 20 matrix 20a first base material 20b second second Base material 25 resist pattern layer

Claims (6)

A substrate for a semiconductor device in which a metal part that becomes a lead (3) and/or a die pad (4) is formed on a matrix (20),
The master mold (20) includes a first base material (20a) and a second base material (20b) on which the metal part is formed,
The first base material (20a) is formed by plating on the second base material (20b),
The matrix (20) is separable between the first substrate (20a) and the second substrate (20b),
A semiconductor device, wherein the first base material (20a) is thinner than the second base material (20b) and is made of a softer material than the second base material (20b). substrate. The surface of the second base material (20b) is subjected to release treatment, and the first base material (20a) is formed on the second base material (20b) subjected to the release treatment. 2. The semiconductor device substrate according to claim 1. 3. The semiconductor device according to claim 1, wherein the thickness of the first base material (20a) is 10-30 μm, and the thickness of the second base material (20b) is 100-500 μm. substrate. The strength of adhesion between the metal portion and the first base material (20a) is stronger than the strength of adhesion between the first base material (20a) and the second base material (20b). 4. The semiconductor device substrate according to claim 1, wherein: A method for manufacturing a semiconductor device using the semiconductor device substrate according to any one of claims 1 to 4, wherein the semiconductor element (2) and the metal portion are sealed with a resin, and the metal portion is exposed on the bottom surface. There is
forming a resist pattern layer (25) on the surface of the first substrate (20a) of the master mold (20);
forming the metal part on the surface of the first base material (20a) exposed from the resist pattern layer (25);
removing the resist pattern layer (25);
a step of mounting the semiconductor element (2) on the metal part and electrically connecting the semiconductor element (2) and the metal part;
a step of molding the semiconductor element (2) and the metal part with a sealing resin (38) to form a resin sealing body (7);
removing the matrix (20) from the resin sealing body (7);
In the step of removing the matrix (20), after peeling and removing the second base material (20b) from the first base material (20a), the first base material ( 20a) is removed by peeling. The strength of adhesion between the metal portion and the first base material (20a) is stronger than the strength of adhesion between the first base material (20a) and the second base material (20b), The strength of the adhesion between the sealing resin (38) and the first base material (20a) is determined by the strength of the adhesion between the first base material (20a) and the second base material (20b). strength, and the strength of adhesion between the metal portion and the sealing resin (38) is stronger than the strength of adhesion between the metal portion and the first base material (20a). 6. The method of manufacturing a semiconductor device according to claim 5, wherein

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