JP7614295B2 - Substrate for semiconductor device and semiconductor device - Google Patents

Description

The present invention relates to a substrate for a semiconductor device that has a metal part that serves as a semiconductor element mounting part and an electrode part on a mother substrate, and a semiconductor device that uses the substrate for a semiconductor device.

A semiconductor device in which a semiconductor element is mounted on a substrate (printed circuit board) for supporting the semiconductor element, the semiconductor element is electrically connected to a terminal for external output, and the entire substrate including the semiconductor element is covered with a protective material such as resin, has a limit to how small it can be made due to its structure. In contrast, a semiconductor device in which a metal part that serves as a semiconductor element mounting part and an electrode part is provided, the semiconductor element is mounted on this metal part, and after processing such as electrical connection, the surface side of the semiconductor element and the metal part are sealed with a sealing material such as resin, and the metal part is exposed from the bottom, can be made low in height to save space, and has the advantage of being excellent in terms of heat dissipation, as heat generated by the semiconductor element can be released to the outside through the exposed metal part, and is therefore increasingly used in the field of small semiconductor devices such as chip size.

Such semiconductor devices are mainly manufactured through a manufacturing process in which metal parts that will become the semiconductor element mounting parts and electrode parts are formed on a conductive mother substrate by plating (electroforming) in the desired number of semiconductor devices at once, the surface side of the metal parts that have been subjected to processes such as mounting the semiconductor elements and electrically connecting the semiconductor elements to the electrode parts is sealed with a sealant, and then only the mother substrate is removed and the many integrated semiconductor devices are cut into individual pieces. Examples of manufacturing methods for such semiconductor devices are disclosed in Patent Documents 1 and 2.

JP 2002-9196 A JP 2004-214265 A

As shown in the above-mentioned patent document, in the conventional method of manufacturing a semiconductor device, when forming metal parts on a mother substrate, a resist layer is formed in advance on the parts of the mother substrate where the metal parts are not to be placed, so that the metal parts are formed in the appropriate positions by electrolytic plating. Metals such as nickel, which are suitable for formation by plating, are used for these metal parts. Then, after dissolving and removing this resist layer with a solvent or the like, the mother substrate and the metal parts formed on its surface are supplied as a substrate for a semiconductor device. Using this substrate for a semiconductor device, the mounting of semiconductor elements, wiring, sealing with a sealing material, etc. are carried out in the actual manufacturing process of the semiconductor device.

The present invention has been made to solve the above problems, and aims to provide a substrate for a semiconductor device that can further reduce the size of the semiconductor device and increase the formation density of the semiconductor device, and a semiconductor device that uses this substrate for a semiconductor device.

However, in conventional processes, it is difficult to precisely control the amount of overhang of the overhanging parts on the upper part of the metal part, so the metal parts must be spaced apart widely so that the gap between the overhanging parts is not so narrow that it would prevent the subsequent removal of the resist layer. This makes it difficult to further miniaturize the semiconductor device and to improve production efficiency by increasing the formation density of the semiconductor device on the semiconductor device substrate.

The present invention has been made to solve the above problems, and aims to provide a substrate for a semiconductor device that can further reduce the size of the semiconductor device and increase the formation density of the semiconductor device, and a semiconductor device that uses this substrate for a semiconductor device.

The substrate for semiconductor device according to the present invention comprises a metal part 11 which becomes a semiconductor element mounting part 11a and/or an electrode part 11b on a mother substrate 10. A protruding part 11c is formed on the metal part 11. The protruding part 11c has a lower surface which is parallel to a direction perpendicular to the axial direction of the metal part 11, an upper surface which is formed continuously with the upper surface of the metal part 11, and a side surface which is formed between the lower surface and the upper surface.

The side of the protrusion 11c is parallel to the axial direction of the metal part 11. The height of the protrusion 11c is the same as or greater than the width of the protrusion 11c.

In addition, a surface metal layer 13 is formed on the upper surface of the metal portion 11 and the upper surface of the protruding portion 11c, and the thickness of the surface metal layer 13 appears as the side surface of the protruding portion 11c.

Furthermore, the metal part 11 is formed with the protruding part 11c and/or the protruding part 11c', and this protruding part 11c' has a lower surface parallel to a direction perpendicular to the axial direction of the metal part 11, and an upper surface formed continuous with the upper surface of the metal part 11. In this way, the metal part 11 is formed with the protruding part 11c having a side surface and/or the protruding part 11c' not having a side surface, resulting in a configuration in which different protruding parts are mixed.

The present invention also provides a method for manufacturing a substrate for a semiconductor device having a metal portion 11 that becomes a semiconductor element mounting portion 11a and/or an electrode portion 11b on a mother substrate 10, the method including the steps of forming a first resist layer 12 of a predetermined pattern for forming the metal portion 11 on the mother substrate 10, forming a second resist layer 16 of a predetermined pattern on the first resist layer 12, and forming the metal portion 11 on the exposed area of the mother substrate 10 that is not covered by the first resist layer 12. In the step of forming the metal portion 11, the metal portion 11 is formed to a predetermined thickness that exceeds the thickness of the first resist layer 12 but does not exceed the thickness of the second resist layer 16, and includes a portion that contacts the side surface of the second resist layer 16, thereby forming a protruding portion 11c on the metal portion 11.

The second resist layer 16 is formed so that the inner surface of the opening of the predetermined pattern is parallel to a direction perpendicular to the surface direction of the mother substrate 10. Here, "the inner surface of the opening of the predetermined pattern of the second resist layer 16 is perpendicular to the surface direction of the mother substrate 10" means that when a straight line (imaginary line) is drawn from the inner surface of the opening of the predetermined pattern of the second resist layer 16 toward the surface of the mother substrate 10, it intersects at a right angle.

A step portion 20 is formed between the inner surface of the opening of the predetermined pattern of the first resist layer 12 and the inner surface of the opening of the predetermined pattern of the second resist layer 16, and the width dimension of the step portion 20 is set to 5 μm or more. Note that there may be a portion where this step portion 20 is not formed, that is, there may be an area where the second resist layer 16 is not formed on the first resist layer 12, and thus, in the process of forming the metal portion 11, the metal layer 11 is formed to a thickness exceeding that of the first resist layer 12, thereby forming a protruding portion 11c' in the metal portion 11.

The present invention also provides a semiconductor device that includes a semiconductor element 14 and a metal part 11 that serves as a semiconductor element mounting part 11a and/or an electrode part 11b, the metal part 11 having a protruding part 11c formed therein, the semiconductor element 14 being mounted and electrically connected to the metal part 11, and sealed with a sealing material 19, the protruding part 11c having a lower surface parallel to a direction perpendicular to the axial direction of the metal part 11, an upper surface formed continuously with the upper surface of the metal part 11, and a side surface formed between the lower surface and the upper surface.

According to the present invention, the protrusions 11c can be adjusted to a predetermined appropriate distance between adjacent protrusions 11c while ensuring the minimum amount of protrusion necessary to provide sufficient strength against leakage from the sealing material. This allows the arrangement interval of the metal parts 11 on the mother substrate 10 to be smaller than in the past, further miniaturizing the semiconductor device formed on the substrate 1 for semiconductor device, and increasing the formation density of the semiconductor device on the substrate 1 for semiconductor device, thereby making the manufacturing of semiconductor devices more efficient. Moreover, the protrusions 11c can be easily obtained by forming the first resist layer 12 and the second resist layer 16 into the desired shape.

1 is a partially enlarged view of a substrate for a semiconductor device according to a first embodiment of the present invention; 1 is a cross-sectional view of a substrate for a semiconductor device according to a first embodiment of the present invention; 3A and 3B are explanatory views of a metal portion in the substrate for the semiconductor device according to the first embodiment of the present invention. 1 is an explanatory diagram of a semiconductor device according to a first embodiment of the present invention; 1A to 1C are diagrams illustrating steps in a method for manufacturing a substrate for a semiconductor device according to a first embodiment of the present invention. 1A to 1C are diagrams illustrating steps in a method for manufacturing a substrate for a semiconductor device according to a first embodiment of the present invention. 3A to 3C are diagrams illustrating a state of a metal portion in the substrate for the semiconductor device according to the first embodiment of the present invention. 1A to 1C are diagrams illustrating steps in a manufacturing method of a semiconductor device according to a first embodiment of the present invention. 11 is an explanatory diagram of a metal portion in a substrate for a semiconductor device according to another embodiment of the present invention. 11 is an explanatory diagram of a semiconductor device according to another embodiment of the present invention. 10A to 10C are diagrams illustrating steps in a method for manufacturing a substrate for a semiconductor device according to another embodiment of the present invention. 11 is an explanatory diagram of a substrate for a semiconductor device according to another embodiment of the present invention. FIG. FIG. 1 is a cross-sectional view showing a conventional substrate for a semiconductor device.

First Embodiment
A substrate for a semiconductor device according to a first embodiment of the present invention will now be described with reference to Figures 1 to 3. As shown in the figures, the substrate for a semiconductor device 1 according to this embodiment includes a mother substrate 10 made of a conductive material, and a plurality of metal parts 11 formed on the mother substrate 10 to serve as semiconductor element mounting parts 11a or electrode parts 11b of a semiconductor device 70 manufactured using the substrate for a semiconductor device 1. A surface metal layer 13 is formed on the surface of the metal parts 11 by plating.

Figure 2 shows a schematic configuration of a substrate for a semiconductor device, and Figure 3 shows a schematic configuration of metal part 11, with Figure 3(A) being a top view, Figure 3(B) being a cross-sectional view, Figure 3(C) being a bottom view, and Figure 3(D) being a perspective view. As shown in Figure 3, a protruding part 11c is provided on the periphery of metal part 11, preferably on the upper end periphery, and this protruding part 11c has a lower surface A parallel to a direction perpendicular to the axial direction of metal part 11, an upper surface C formed continuously with upper surface D of metal part 11, and a side surface B formed between the lower surface and the upper surface. Metal part 11 and protruding part 11c are formed in a circular shape when viewed from above. In FIG. 3, a line is drawn at the boundary between the top surface D of the metal part 11 and the top surface C of the protruding part 11c, but this is to clearly show the area of the top surface D of the metal part 11 and the top surface C of the protruding part 11c. In reality, the top surface D of the metal part 11 and the top surface C of the protruding part 11c are continuous surfaces with no boundary.

The upper surface C of the protruding portion 11c is a curved surface. Specifically, the upper surface C of the protruding portion 11c is a curved surface that is continuously formed from the upper surface D of the metal portion 11 to the side surface B of the protruding portion 11c. Note that the surfaces of the metal portion 11 (upper surface D, side surface, lower surface) and the surfaces of the protruding portion 11c (upper surface C, side surface B, lower surface A) may be convex or concave.

Here, the dimensions of the metal part 11 (semiconductor element mounting part 11a, electrode part 11b) and the overhanging part 11c will be described. As shown in FIG. 3B, the width dimension W1 of the metal part 11 is preferably 50 μm or more, the height dimension H1 of the metal part 11 is preferably 20 to 100 μm, the width dimension W2 of the overhanging part 11c is preferably 5 μm or more, and the height (thickness) dimension H2 of the overhanging part 11c is preferably in the range of 5 to 50 μm. In addition, it is preferable that the width dimension (overhang length) W2 of the overhanging part 11c and the height dimension H2 of the overhanging part 11c satisfy the relationship W2≦H2. This allows the arrangement interval of the metal part 11 to be reduced while ensuring the strength of the overhanging part 11c. The outer dimensions of the metal part 11 and the overhanging part 11c can be easily set by forming the first resist layer 12 and the second resist layer 16 described later into the desired shape. In this embodiment, the width dimension W1 of the semiconductor element mounting portion 11a of the metal portion 11 is set to 500 μm, the width dimension W1 of the electrode portion 11b is set to 250 μm, the height dimension H1 of the metal portion 11 is set to 70 μm, the width dimension W2 of the protruding portion 11c is set to 20 μm, and the height (thickness) dimension H2 of the protruding portion 11c is set to 30 μm.

As shown in FIG. 4, the semiconductor device 70 manufactured using the semiconductor device substrate 1 includes, in addition to the metal part 11 and surface metal layer 13 obtained from the semiconductor device substrate 1, a semiconductor element 14 mounted on the semiconductor element mounting portion 11a of the metal part 11, a wire 15 electrically connecting the semiconductor element 14 to the electrode portion 11b of the metal part 11, and a sealant 19 that covers and seals the surface side of the metal part 11 including the semiconductor element 14 and the wire 15.

At the bottom of this semiconductor device 70, the back surface of the metal part 11 is exposed from the sealing material 19 as an electrode, heat dissipation pad, etc. (see FIG. 4B). The exposed back surface of the metal part 11 and the back surface of the sealing material 19 that appears as part of the device exterior are located on approximately the same plane. On each surface of the semiconductor device 70 other than the bottom, only the sealing material 19 that forms the device exterior is exposed. However, this is not limited to this, and a part of the metal part 11 (the side of the metal part 11) may be exposed on each surface of the semiconductor device 70 other than the top (front, back, left and right side surfaces, bottom surface).

The semiconductor device substrate 1 is manufactured by forming a first resist layer 12 corresponding to the non-placement portion of the metal portion 11 on the mother substrate 10, forming a second resist layer 16 that adjusts and controls the shape of the upper portion of the metal portion 11 (the amount of protrusion of the protruding portion 11c), and then forming the metal portion 11 by plating, and removing the first resist layer 12 and the second resist layer 16. The surface metal layer 13 can be formed by plating the surface of the metal portion 11 including the surface of the protruding portion 11c following the formation of the metal portion 11. Here, by forming the surface metal layer 13 on the upper surface C of the protruding portion 11, the thickness of the surface metal layer 13 appears on the side surface B of the protruding portion 11c, but the surface metal layer 13 may be formed on the entire side surface B of the protruding portion 11c. This makes it possible to further expand the area that has excellent bonding properties with the wire 15 while ensuring the strength of the protruding portion 11c and the placement interval of the metal portion 11. Furthermore, if the surface metal layer 13 is formed on the entire side surface B of the protruding portion 11c, the thickness of the surface metal layer 13 will be present on the underside A of the protruding portion 11c. In this way, the surface metal layer 13 may be formed not only on the upper surface C of the protruding portion 11, but also on part or the entire surface of the side surface B and underside A of the protruding portion 11.

When manufacturing a semiconductor device using this semiconductor device substrate 1, the semiconductor element 14 is mounted and wired on the surface side of the metal part 11 of the semiconductor device substrate 1, and then the substrate 10 is sealed with a sealing material 19, and the mother substrate 10 is removed from the semiconductor device portion (the portion sealed with the sealing material) to obtain the semiconductor device 70.

The mother substrate 10 is formed of a conductive metal plate of stainless steel (e.g., SUS430), aluminum, copper, etc., with a thickness of about 0.1 mm, and constitutes a major part of the substrate 1 for the semiconductor device until it is removed in the manufacturing process of the semiconductor device. At each stage of the manufacturing process of the substrate for the semiconductor device, a first resist layer 12, a second resist layer 16, and a metal part 11 are formed on the front side, and a resist layer 18 is disposed on the back side. When forming the metal part 11, electricity is passed through the mother substrate 10, and the metal part 11 is formed by electrolytic plating on the part of the mother substrate 10 surface that is not covered by the first resist layer 12 and the second resist layer 16 and can be electrically conducted. In addition, when the surface metal layer 13 is also formed by electrolytic plating, electricity is passed through the mother substrate 10.

The metal parts 11 are made of nickel or copper suitable for electrolytic plating, or a nickel alloy such as nickel-cobalt, and are formed by electrolytic plating in the areas of the mother substrate 10 where there is no first resist layer 12. In the substrate 1 for semiconductor device, the metal parts 11 are formed on the surface of the mother substrate 10 in a form in which a combination of a semiconductor element mounting part 11a and an electrode part 11b arranged in the vicinity thereof is regarded as one unit, and a large number of such combinations are aligned in an order equal to the number of semiconductor devices to be manufactured.

The metal part 11 is formed to a thickness (for example, about 20 to 100 μm) that exceeds the thickness of the first resist layer 12, and has a shape with a generally eaves-like protruding part 11c that protrudes toward the second resist layer 16 at the upper end periphery. The protruding part 11c is obtained as a shape that protrudes from the upper end of the metal part 11 beyond the first resist layer 12 to the second resist layer 16 side by continuing the electrolytic plating even after the metal part 11 is formed to the thickness of the first resist layer 12, so that the growth of the metal part 11 proceeds not only in the thickness direction (the axial direction of the metal part 11) but also in the direction toward the second resist layer 16 (the direction perpendicular to the axial direction of the metal part 11). Here, the growth of the metal part 11 toward the second resist layer 16 by electrolytic plating can be restricted from further growth in that direction by the presence of the second resist layer 16, and the interval between the metal parts 11 can be made constant. Furthermore, when the protruding portion 11c is sealed with the sealing material 19, it becomes sandwiched and fixed by the sealing material 19.

In addition, the semiconductor element mounting portion 11a of the metal portion 11 can be provided with a recess into which the semiconductor element 14 can be inserted and mounted during the manufacture of the semiconductor device. When the semiconductor element 14 is inserted and arranged in this recess, the position of the semiconductor element 14 can be lowered by the depth of the recess compared to the conventional case where the semiconductor element 14 is mounted on the upper surface of the semiconductor element mounting portion. This recess is deep enough to ensure a thickness below the recess that maintains the necessary strength of the semiconductor element mounting portion 11a. A recess can also be provided in the electrode portion 11b. When the sealing material 19 is sealed in this recess, the upper surface of the electrode portion and the sealing material of the semiconductor device come into contact widely due to the recess, improving the support strength of the electrode portion in the semiconductor device and increasing durability. In addition, when a structure is adopted in which the electrode portion is exposed not only to the bottom but also to the side due to the need for mounting the semiconductor device, a recess is provided in the electrode portion 11b and this recess is cut and separated, so that the cutting position is lowered by the depth of the recess, reducing the amount of metal cut in the cutting process, reducing the burden on the cutting device associated with cutting, and suppressing deterioration of the blade portion. The shape of the recess is not limited to a bottomed one, but may be a through hole.

The metal part 11 is mostly made of nickel or a nickel alloy suitable for electrolytic plating, but on the back side of the metal part 11, a thin film 11d of a metal with better solder wettability than the main material part such as nickel, for example, gold, tin, palladium, solder, etc. is arranged so that soldering can be performed appropriately when mounting the semiconductor device (see FIG. 6(B)). The thickness of this thin film 11d is preferably about 0.01 to 1 μm. In addition, the thin film 11d can also be given a function to prevent the metal part 11 from being corroded and deteriorated by the etching solution when the mother substrate 10 is etched away, and in that case, it is preferable to arrange a thin film of gold, silver, tin, etc. Note that the formation of this thin film on the back side of the metal part 11 is not limited to before forming the main material part of the metal part 11 by electrolytic plating, but may be formed on the exposed back side of the metal part 11 by plating after the semiconductor device 70 is completed.

The surface metal layer 13 is formed as a plating film made of a metal, such as gold or silver, that has excellent bonding properties with the gold wires that form the wiring wires 15. This surface metal layer 13 is formed as a plating of a predetermined thickness, for example, about 0.1 to 1 μm in the case of gold plating and about 1 to 10 μm in the case of silver plating, on the surface of the metal part 11 and the protruding part 11c by a plating bath for each mother substrate 10. When plating the surface metal layer 13, the back side of the mother substrate 10 is covered with a resist layer 18, so that no plating adhesion occurs (see FIG. 6 (D)). In this way, by forming the surface metal layer 13 on the upper surface D of the metal part 11 and the upper surface C of the protruding part 11c, the thickness of the surface metal layer 13 appears as the side surface B of the protruding part 11c, so that the surface area of the surface metal layer 13 that has excellent bonding properties with the wires 15 can be increased. When plating the surface metal layer 13, a plating solution that corresponds to the metal to be plated will be used, such as a plating solution that is different from that used for plating the metal portion 11.

When plating this surface metal layer 13, if the plating is difficult to adhere, it is desirable to first perform a base plating (copper strike plating, silver strike plating, or gold strike plating) on the surface of the metal part 11 before plating the surface metal layer 13, in order to improve the adhesion of the surface metal layer 13 to the metal part 11.

Next, we will explain the method for manufacturing a substrate for a semiconductor device according to this embodiment and the method for manufacturing a semiconductor device using the substrate for a semiconductor device.

The method for manufacturing a substrate for a semiconductor device includes the steps of forming resist layers 12 and 18 on the front and back of the mother substrate 10, forming a second resist layer 16 on the upper side of the first resist layer 12 in a position where it is desired to suppress the formation of the metal portion 11 formed as the protruding portion 11c, forming the metal portion 11 to a predetermined thickness on the portion of the surface of the mother substrate 10 that is not covered by the first resist layer 12 and the second resist layer 16, forming a surface metal layer 13 on the surface of the metal portion 11, and removing the first resist layer 12, the second resist layer 16 on the front side of the mother substrate 10, and the resist layer 18 on the back side. Each of these steps for manufacturing a substrate for a semiconductor device is specifically described below.

First, in order to plate the metal parts 11 on the mother substrate 10, a first resist layer 12 is formed on the mother substrate 10 so that the parts where the metal parts 11 are to be disposed are exposed (corresponding to the parts where the metal parts 11 are not disposed). Specifically, a photosensitive resist 12a is formed on the front side of the mother substrate 10 to a predetermined thickness (for example, about 50 μm) corresponding to the metal parts 11 to be formed (see FIG. 5(A)). The photosensitive resist 12a is subjected to processes such as curing by exposure to ultraviolet light and development to remove the resist from the non-irradiated parts while a mask film of a predetermined pattern corresponding to the positions where the metal parts 11 are disposed is placed on the photosensitive resist 12a, thereby forming a first resist layer 12 having an opening pattern corresponding to the parts where the metal parts 11 are not disposed (see FIG. 5(B)). In addition, a photosensitive resist is also formed on the back side of the mother substrate 10 in the same manner as on the front side, and a resist layer 18 is formed over the entire back side through a process such as exposure to light.

In the process of forming the second resist layer 16, the second resist layer 16 is disposed on the first resist layer 12 formed initially, corresponding to the area where the formation of the metal portion 11 is to be suppressed. Specifically, a photosensitive resist 16a is disposed in close contact with the surface side of the mother substrate 10 and the first resist layer 12 so as to have a predetermined thickness (for example, about 40 μm) (see FIG. 5 (C)). With a mask film of a predetermined pattern corresponding to the position where the formation of the protruding portion 11c is to be suppressed placed on this photosensitive resist 16a, the photosensitive resist 16a is cured by exposure to ultraviolet light, and developed to remove the resist agent in the non-irradiated portion, forming a second resist layer 16 having an opening pattern corresponding to the area where the metal portion 11 is not to be formed (see FIG. 6 (A)). The presence of this second resist layer 16 makes it possible to regulate the amount of protrusion of the protruding portion 11c when the metal portion 11 is formed by plating. A step 20 is formed between the inner surface of the opening of the predetermined pattern in the first resist layer 12 and the inner surface of the opening of the predetermined pattern in the second resist layer 16 (see FIG. 6A), and the desired amount of protrusion can be achieved by setting the width dimension of this step 20. The width dimension of the step 20 is preferably 5 μm or more, and in this embodiment, it is set to 20 μm. If the width dimension of the step 20 is less than 5 μm, the amount of protrusion is insufficient, and it is difficult to obtain the effect of the protrusion 11c.

After the second resist layer 16 is formed, the exposed areas of the surface of the mother substrate 10 that are not covered by the first resist layer 12 and the second resist layer 16 are pre-treated for plating (acid immersion, cathodic electrolysis, chemical etching, strike plating, etc.). After that, a thin gold film 11d for improving solder wettability is formed on the exposed areas by plating or the like to a thickness of, for example, 0.01 to 1 μm (see FIG. 6(B)). Nickel is then layered on top of this thin film 11d by electrolytic plating to form the metal part 11 (see FIG. 6(C)).

In this metal part 11 forming process, the metal part 11 is formed to a predetermined thickness (for example, about 60 μm) that exceeds the thickness of the first resist layer 12 but does not exceed the upper surface of the second resist layer 16, and a roughly eaves-shaped protruding part 11c that protrudes toward the first resist layer 12 side is formed on the upper edge of the metal part 11 near the first resist layer 12, with a portion that contacts the side of the second resist layer 16 (see FIG. 6 (C)). The formation range of this protruding part 11c is restricted by the second resist layer 16 that is arranged so that the metal part 11 is not formed, so the protruding amount of the protruding part 11c is preset. In addition, the metal part 11 is formed in a form in which a combination of a semiconductor element mounting part 11a and a plurality of electrode parts 11b arranged in the vicinity thereof is treated as one unit on the surface of the mother substrate 10, and a large number of such combinations are arranged in an aligned state in the number of semiconductor devices to be manufactured.

After the metal portion 11 has been formed to a predetermined thickness, a surface metal layer 13 is formed on the surface of the metal portion 11 to a predetermined thickness, for example, about 1 to 10 μm in the case of silver plating (see FIG. 6(D)). The first resist layer 12 and the second resist layer 16 have sufficient resistance to the plating solution used in the plating bath, so they do not deteriorate and maintain their function as resist layers, preventing plating from adhering to areas other than the required areas, such as the metal portion 11. In addition, when plating the surface metal layer 13, the back side of the mother substrate 10 is covered with the resist layer 18, so no plating adheres to it.

After the surface metal layer 13 is formed, the first resist layer 12 on the surface side of the mother substrate 10, the second resist layer 16, and the resist layer 18 on the back side are dissolved and removed with a specific remover, completing the semiconductor device substrate 1 shown in FIG. 2.

In this way, the metal part 11 is formed beyond the thickness of the first resist layer 12, and a generally eaves-shaped protruding part 11c that protrudes toward the first resist layer 12 is formed at the upper end periphery of the metal part 11 near the first resist layer 12 (see FIG. 6(C)). At this time, since the second resist layer 16 is disposed on the first resist layer 12, the protruding part 11c is formed with a portion that contacts the side of the second resist layer 16, with its formation range being regulated by the second resist layer 16. As a result, the protruding amount of the protruding part 11c is managed to a predetermined amount based on the arrangement of the second resist layer 16 that is set in advance. In this case, since each of the adjacent metal parts 11 on the mother substrate 10 has a protruding part 11c at the top, and these protruding parts 11c can be adjusted to a state where they are spaced apart from each other at a predetermined appropriate interval, the arrangement interval of the metal parts on the mother substrate 10 can be made smaller than in the past. That is, in the conventional process, since the amount of overhang of the overhanging portion of the metal portion cannot be strictly controlled, it was necessary to arrange the metal portions 11 at a wide interval so that the interval between the overhanging portions would not become too narrow to prevent the subsequent removal of the resist, whereas in the present embodiment, since the amount of overhang of the overhanging portion 11c can be adjusted by the arrangement of the second resist layer 16, even if the arrangement interval of the metal portions 11 is narrowed, the amount of overhang of the overhanging portion 11c can be suppressed to an extent that the resist can be removed without problems, and the minimum interval between adjacent metal portions 11 can be made an appropriate amount. Also, by adjusting the amount of overhang of the overhanging portion of the metal portion 11 that faces the side surface of the semiconductor device (sealing material 19), it is possible to prevent the metal portion 11 from protruding from the sealing material 19. The spacing between the metal parts 11 can be made small to the extent that the minimum amount of overhang required to provide sufficient strength against removal at the overhanging parts 11c is ensured, and the remover for the first resist layer 12 can reach between the metal parts 11 to properly remove the first resist layer 12 (see FIG. 7). By making the side surface B of the overhanging parts 11c parallel to the axial direction of the metal parts 11, the spacing between the metal parts 11 can be made more accurate and appropriate. This allows the semiconductor device formed on the substrate 1 for semiconductor device to be further miniaturized, and increases the formation density of the semiconductor device on the substrate 1 for semiconductor device, making the manufacturing of the semiconductor device more efficient.

In addition, by forming the second resist layer 16 following the process of forming the first resist layer 12 on the mother substrate 10 and then forming the metal portion 11, the formation range of the metal portion 11 (protruding portion 11c) that reaches the upper side of the first resist layer 12 can be controlled, and the resist layers 12 and 16 can be formed together in advance to form the metal portion 11 in one process (one plating), thereby improving production efficiency. In the above explanation, when forming the first resist layer 12 and the second resist layer 16, the first resist layer 12 is formed and then the second resist layer 16 is formed, but in the process of forming the first resist layer 12, after the photosensitive resist 12a is exposed to light in a predetermined pattern, the photosensitive resist 16a may be formed on the photosensitive resist 12a without development, and after the photosensitive resist 16a is exposed to light in a predetermined pattern, the photosensitive resist 12a and the photosensitive resist 16a (unexposed portion) may be developed together. In this case, the photosensitive resist 16a (second resist layer 16) is formed on the photosensitive resist 12a formed on one side of the mother substrate 10, so that the photosensitive resist 16a can be easily formed and the development process can be completed in one step. Furthermore, the photosensitive resist 12a and the photosensitive resist 16a can be formed using resists having different exposure sensitivities. For example, if the photosensitive resist 12a and the photosensitive resist 16a having a lower exposure sensitivity than the photosensitive resist 12a are laminated in order on the mother substrate 10, the state in which the second resist layer 16 is formed on the first resist layer 12 as shown in FIG. 6(A) can be obtained by one exposure and development process. Furthermore, the exposure of the photosensitive resist 12a and the photosensitive resist 16a is performed using a mask having a predetermined pattern formed thereon, but it is also possible to directly expose them using a direct writing exposure device.

Next, a method for manufacturing a semiconductor device using the obtained semiconductor device substrate 1 will be described. First, a semiconductor element 14 is mounted on the semiconductor element mounting portion 11a of the metal portion 11 of the semiconductor device substrate 1 with an adhesive interposed therebetween, and the semiconductor element 14 is fixed in an adhesive state. Furthermore, the electrodes on the surface of the semiconductor element 14 are joined to the corresponding electrode portions 11b by wires 15 such as gold wires, and the semiconductor element 14 and each electrode portion 11b are electrically connected (see FIG. 8(A)). This electrical connection by wiring is performed by an ultrasonic bonding device or the like. Since a surface metal layer 13 is formed on the surface of the electrode portion 11b, the connection with the wire 15 can be made reliable, and the reliability of the connection can be improved. This semiconductor element 14 is a so-called chip on which a fine electronic circuit is formed. The adhesive may be solid, viscous, or liquid, and examples of the adhesive include silver paste, resin paste, and die attach film. Although the electrical connection between the semiconductor element 14 and the electrode portion 11b is performed by wire bonding, it may also be performed by flip chip method.

After the connection between the semiconductor element 14 and each electrode portion 11b is completed, the area on the surface side of the mother substrate 10 that will become the semiconductor device, including the metal portion 11, etc., is sealed with a sealing material 19 such as a thermosetting epoxy resin with high physical strength, isolating the semiconductor element 14 and wires 15 from the outside and protecting them (see FIG. 8(B)). In detail, the surface side of the mother substrate 10 is attached to a mold die that will become the upper die, and the sealing is performed in the process of pressing the epoxy resin before hardening that will become the sealing material 19 into the mold die while the mother substrate 10 plays the role of the lower die, and on the mother substrate 10, the combination of the semiconductor element mounting portion 11a and the multiple electrode portions 11b that will become one semiconductor device is uniformly sealed in a multiplicity of aligned states, and the semiconductor device appears in a multiplicity of connected states. Note that when the semiconductor element 14 is a light-emitting element such as an LED, a light-transmitting material is used.

Once these multiple connected semiconductor devices are obtained, the mother substrate 10 is removed, leaving the back side of the metal part 11 exposed at the bottom of each semiconductor device (see FIG. 8(C)). The mother substrate 10, which is made of stainless steel, is removed by physically peeling it off from the semiconductor device. By using stainless steel, which has excellent strength and peelability, as the mother substrate 10, it can be peeled off from the semiconductor device and quickly removed. At this time, by making the sealing material 19 have sufficient physical strength, even when the mother substrate 10 is peeled off and removed, it can maintain its integrated state with the metal part 11 without cracking or other damage.

In addition, when the mother substrate 10 is made of another metal material, for example, copper, the mother substrate 10 can be removed by immersing it in an etching solution and dissolving it. In this etching, an etching solution is used that has selective etching properties such that the mother substrate 10 dissolves but the material of the metal portion 11 and the surface metal layer 13 is not damaged. When removing by dissolution, no excessive force is applied to the semiconductor device, so the probability of adverse effects occurring due to removal of the mother substrate 10 can be reduced.

At the bottom of the semiconductor device after the mother substrate 10 has been removed, the exposed back side of the metal part 11 and the back side of the sealing material 19 are positioned on approximately the same plane. After removing the mother substrate 10, the multiple connected semiconductor devices are separated one by one to complete the semiconductor device 70.

Inside the obtained semiconductor device 70, the upper edge of the metal part 11 is formed as a protruding part 11c that protrudes in a roughly eave-like shape, and in a sealed state with the sealing material 19, this protruding part 11c is surrounded and fixed by the hardened sealing material 19. Therefore, the protruding part 11c bites into the sealing material 19, which is tightly integrated with the resin, and acts as a resistor against external forces applied to the metal part 11. Even if an external force is applied to the back side of the metal part 11 to separate it from the device exterior, such as when stainless steel or the like is used for the mother substrate 10 and the mother substrate 10 is physically peeled off and removed from the semiconductor device side, the protruding part 11c prevents the metal part 11 from moving, and it is possible to eliminate the misalignment of the metal part 11 with respect to other parts, thereby improving the yield during manufacturing, increasing the strength of the semiconductor device, and improving the durability during use and the reliability of the operation of the semiconductor device.

The first resist layer 12, the second resist layer 16, and the resist layer 18 are formed of an insulating material that is resistant to dissolution in the plating solution used in plating the metal part 11 and the surface metal layer 13. The first resist layer 12, the second resist layer 16, and the resist layer 18 can be formed, for example, by disposing an alkali-developable photosensitive film resist by thermocompression bonding or the like, and then undergoing various processes such as exposure and development. The first resist layer 12, the second resist layer 16, and the resist layer 18 are not limited to the above-mentioned photosensitive resist, and can also be formed by applying a paint that is not altered by the plating solution and can provide a strong coating film to the non-positioned parts of the metal part 11 on the mother substrate 10 and the positions where the formation of the protruding parts 11c is to be restricted, to the required coating thickness by electrochemical coating or the like.

In the above embodiment, the metal part 11 is cylindrical, but it may be a square prism as shown in FIG. 9 or a triangular prism. The shape of the lower part of the metal part 11 (the part formed within the thickness of the first resist layer 12) may be different from the shape of the upper part and the protruding part 11c of the metal part 11 (the part formed within the thickness of the second resist layer 16). For example, the lower part of the metal part 11 may be formed in a square prism shape, and the upper part of the metal part 11 and the protruding part 11c may be formed in a cylindrical shape. Such a shape can be obtained by forming the opening pattern in the first resist layer 12 in a square shape and the opening pattern in the second resist layer 16 in a circular shape. In this way, the shapes of the metal part 11 and the protruding part 11c can be freely set by forming the opening patterns of the first resist layer 12 and the second resist layer 16 in the desired shapes.

In addition, the second resist layer 16 formed on the first resist layer 12 may be partially formed to regulate the amount of overhang of the overhang 11c. This is because it is required to secure as large an area as possible for the surface of the metal part 11 (semiconductor element mounting part 11a) in order to prevent the adhesive (paste) used when mounting the semiconductor element 14 on the metal part 11 (semiconductor element mounting part 11a) from falling off the surface of the metal part 11 (semiconductor element mounting part 11a). However, since the shape and dimensions of the semiconductor device and the position, shape and dimensions of the back surface of the metal part 11 exposed from the bottom of the semiconductor device (the back surface of the sealing material 19) as an external electrode or heat dissipation pad are determined as specifications, if the shape and dimensions of the front surface of the metal part 11 are made the same as the shape and dimensions of the back surface of the metal part 11, the surface area of the metal part 11 will be small. Therefore, by adopting a configuration in which some overhanging portions have side B and others do not, specifically, as shown in FIG. 10, only the overhanging portion 11c that faces the side of the semiconductor device (sealing material 19) has side B, it is possible to ensure a large surface area of the metal portion 11. This configuration is achieved by partially forming the second resist layer 16, that is, the overhang amount of the overhanging portion 11c on the side of the metal portion 11c that faces the side of the semiconductor device (sealing material 19) is restricted, and the overhang amount of the overhanging portion 11c on the side adjacent to the metal portion 11 is not restricted. Below, a method for manufacturing a substrate for a semiconductor device having such a configuration will be described with reference to FIG. 11.

First, a photosensitive resist 12a is formed on the surface side of the mother substrate 10, and the photosensitive resist 12a is exposed, developed, and other processes are performed to form a first resist layer 12. Then, a photosensitive resist 16a is formed on the surface side of the mother substrate 10 and the first resist layer 12. A resist layer 18 is also formed on the back side of the mother substrate 10. Since the process up to this point is the same as the above embodiment (see FIG. 5), a detailed description is omitted, but the photosensitive resist 12a is formed to a thickness of 20 to 40 μm (25 μm in this case), and the photosensitive resist 16a is formed to a thickness of 30 to 80 μm (45 μm in this case). Next, with a mask film of a predetermined pattern corresponding to the position where the formation of the protruding portion 11c is to be suppressed placed on the photosensitive resist 16a, a process such as curing by exposure to ultraviolet light irradiation and development to remove the resist in the non-irradiated portion is performed to form a second resist layer 16 having an opening pattern corresponding to the position where the metal portion 11 is not to be formed (see FIG. 11 (A)). The presence of this second resist layer 16 makes it possible to regulate the amount of overhang of the overhang 11c when the metal portion 11 is plated. Here, the second resist layer 16 is formed at a position facing the side of the semiconductor device (sealing material 19). A step 20 is formed between the inner surface of the opening of the predetermined pattern of the first resist layer 12 and the inner surface of the opening of the predetermined pattern of the second resist layer 16. The width of this step 20 is the amount of overhang of the overhang 11c, and the width of the step 20 is preferably 5 μm or more.

After the second resist layer 16 is formed, the exposed area of the surface of the mother substrate 10 that is not covered by the first resist layer 12 and the second resist layer 16 is pre-treated for plating (acid immersion, cathodic electrolysis, chemical etching, strike plating, etc.), and then the thin film 11d and the metal part 11 are laminated on the exposed area (see FIG. 11(B)). Here, the thin film 11d is plated with gold to a thickness of 0.01 to 1 μm, and the metal part 11 is plated with nickel to a thickness of 50 to 100 μm on the thin film 11d. At this time, the metal part 11 is formed to a thickness exceeding that of the first resist layer 12, and in the area where the second resist layer 16 is formed, it is formed to a predetermined thickness (here, 60 μm) that does not exceed the upper surface of the second resist layer 16, and at the upper end periphery of the metal part 11 near the first resist layer 12, a roughly eaves-shaped protruding part 11c protruding toward the first resist layer 12 side is formed with a part that contacts the side of the second resist layer 16. The shape of the protrusion is different in the area where the second resist layer 16 is formed and the area where it is not formed. The characteristic is that in the area where the second resist layer 16 is formed, a protrusion 11c having a side B is formed, and in the area where the second resist layer 16 is not formed, a protrusion 11c' without a side B is formed.

After the metal portion 11 is formed, a surface metal layer 13 is formed on the surface of the metal portion 11 (see FIG. 11(C)). Here, the surface metal layer 13 is formed by plating silver to a thickness of 1 to 10 μm. After the surface metal layer 13 is formed, the first resist layer 12, the second resist layer 16, and the resist layer 18 on the front and back of the mother substrate 10 are removed, completing the substrate 1 for the semiconductor device (see FIG. 11(D)).

As for the manufacturing method of the semiconductor device using the semiconductor device substrate 1 obtained in this way, as in the above embodiment (see FIG. 8), the semiconductor element 14 is mounted on the semiconductor element mounting portion 11a, the electrodes of this semiconductor element 14 are joined to the corresponding electrode portions 11b by wires 15 to electrically connect the semiconductor element 14 to each electrode portion 11b, and then the semiconductor device is sealed with a sealing material 19, and the mother substrate 10 is removed and cut out one by one as a semiconductor device to complete the semiconductor device. As a result, even if the position, shape, and dimensions of the exposed back surface of the metal portion 11 at the bottom of the semiconductor device (back surface of the sealing material 19) are specified as an external electrode or heat dissipation pad, the surface shape of the metal portion 11 can be freely set, and a large surface area of the metal portion 11 can be secured.

The surface area of the metal part 11 can be increased by reducing the shape (width) of the second resist layer 16 (increasing the width of the step part 20). However, if the shape (width) of the second resist layer 16 is made too small, it may be difficult to remove the first resist layer 12 formed under the second resist layer 16. Therefore, in consideration of productivity, the manufacturing method shown in FIG. 11 is preferable. In addition, in the semiconductor device shown in FIG. 10 and the semiconductor device substrate shown in FIG. 11(D), the second resist layer 16 is partially formed to restrict the protrusion amount of the protrusion part 11c on the side facing the side of the semiconductor device (sealing material 19). However, as shown in FIG. 12, the protrusion amount of the protrusion part 11c may be restricted on the side adjacent to the metal part 11. In this case, by restricting the side adjacent to the metal part 11 (semiconductor element mounting part 11a and electrode part 11b), the arrangement interval of the metal part 11 can be reduced while ensuring a large surface area of the metal part 11.

REFERENCE SIGNS LIST 1 Substrate for semiconductor device 10 Mother substrate 11 Metal part 11a Semiconductor element mounting part 11b Electrode part 11c Extension part (first extension part)
11c' Overhanging part (second overhanging part)
Reference Signs List 11d thin film 12 first resist layer 13 surface metal layer 14 semiconductor element 15 wire 16 second resist layer 18 resist layer 19 sealing material 20 step portion 70 semiconductor device

Claims (2)

A substrate for a semiconductor device comprising a mother substrate (10) and a plurality of metal portions (11) serving as semiconductor element mounting portions (11a) and/or electrode portions (11b),
A protruding portion is formed on the metal portion (11),
The protruding portion is formed to protrude from the metal portion (11) in a direction perpendicular to an axial direction of the metal portion (11),
The area of the upper surface of the metal portion (11), including the protruding portion, is formed to be larger than the area of the rear surface of the metal portion (11) that is in contact with the front surface of the mother substrate (10);
The protruding portion has a first protruding portion (11c) and a second protruding portion (11c') having different shapes,
The first protruding portion (11c) has a lower surface parallel to a direction perpendicular to the axial direction of the metal portion (11), an upper surface formed continuously with the upper surface of the metal portion (11), and a side surface formed between the lower surface and the upper surface,
an upper surface of the first protruding portion (11c) is a curved surface that is continuously formed from an upper surface of the metal portion (11) to a side surface of the first protruding portion (11c);
The second protruding portion (11c') has a lower surface parallel to a direction perpendicular to the axial direction of the metal portion (11) and an upper surface formed continuously with the upper surface of the metal portion (11),
In each of the metal portions (11), the second protruding portion (11c') is formed on a side facing the adjacent metal portion (11), and the first protruding portion (11c) is formed at a position other than the side facing the adjacent metal portion (11),
A substrate for a semiconductor device, characterized in that in each of the metal portions (11), the amount of protrusion of the second protrusion portion (11c') on the side facing the adjacent metal portion (11) is formed to be greater than the amount of protrusion of the first protrusion portion (11c) at a position other than the side facing the adjacent metal portion (11). A semiconductor device comprising a semiconductor element (14) and a metal portion (11) serving as a semiconductor element mounting portion (11a) and/or an electrode portion (11b), the semiconductor element (14) and the metal portion (11) are electrically connected to each other, and the semiconductor element (14) and the metal portion (11) are sealed with a sealing material (19),
A protruding portion is formed on the metal portion (11),
The protruding portion is formed to protrude from the metal portion (11) in a direction perpendicular to an axial direction of the metal portion (11),
The area of the upper surface of the metal portion (11) including the protruding portion is formed to be larger than the area of the back surface of the metal portion (11) exposed from the bottom surface of the sealing material (19),
The protruding portion has a first protruding portion (11c) and a second protruding portion (11c') having different shapes,
The first protruding portion (11c) has a lower surface parallel to a direction perpendicular to the axial direction of the metal portion (11), an upper surface formed continuously with the upper surface of the metal portion (11), and a side surface formed between the lower surface and the upper surface,
an upper surface of the first protruding portion (11c) is a curved surface that is continuously formed from an upper surface of the metal portion (11) to a side surface of the first protruding portion (11c);
The second protruding portion (11c') has a lower surface parallel to a direction perpendicular to the axial direction of the metal portion (11) and an upper surface formed continuously with the upper surface of the metal portion (11),
In each of the metal portions (11), the second protruding portion (11c') is formed on a side facing the adjacent metal portion (11), and the first protruding portion (11c) is formed in a position other than the side facing the adjacent metal portion (11),
A semiconductor device characterized in that, in each of the metal portions (11), the amount of protrusion of the second protrusion portion (11c') on the side facing the adjacent metal portion (11) is formed to be greater than the amount of protrusion of the first protrusion portion (11c) at a position other than the side facing the adjacent metal portion (11).

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