Semiconductor device and manufacturing method thereof

A semiconductor device includes: a semiconductor substrate; a heat sink mounted on an upper surface of the semiconductor substrate; wirings formed on a lower surface of the semiconductor substrate; and the like. The heat sink is mounted on the upper surface of the semiconductor substrate, and a planar size thereof is approximately the same as that of the semiconductor substrate. Moreover, the heat sink has a thickness of 500 μm to 2 mm, and may be formed to be thicker than the semiconductor substrate. By using the heat sink to reinforce the substrate, a thickness of the semiconductor substrate can be reduced to, for example, about 50 μm. As a result, a thickness of the entire semiconductor device can be reduced.

Priority is claimed to Japanese Patent Application Number JP2006-091170 filed on Mar. 29, 2006, the disclosures of which are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a manufacturing method thereof, and particularly relates to a semiconductor device having improved heat radiation properties and a manufacturing method thereof.

2. Description of the Prior Art

As to circuit devices set in electronic equipment, reduction in size, thickness and weight thereof has heretofore been demanded for adoption thereof in portable telephones, portable computers and the like. In order to satisfy these conditions, a semiconductor device called a CSP (Chip Scale Package) has been developed, which has the same size as that of a semiconductor element to be built thereinto.

Among the CSPs, there is a particularly small WLP (Wafer Level Package). With reference toFIGS. 6A to 6C, a method for manufacturing the WLP will be schematically described. This technology is described for instance in Japanese Patent Application Publication No. 2004-172542.

With reference toFIG. 6A, first, a number of semiconductor device parts102are formed on a semiconductor wafer100. In each of the semiconductor device parts102, a transistor and the like are formed by a diffusion step. Moreover, on an upper surface of each of the semiconductor device parts102, electrodes103are formed, which are connected to elements inside a substrate. Furthermore, an insulating layer101is formed in a state where upper parts of the electrodes103are exposed. On an upper surface of the insulating layer101, wirings104are patterned. Furthermore, the upper surface of the insulating layer101is covered with a covering layer110so as to cover the wirings104. Moreover, openings are provided in the covering layer110in regions where external electrodes105are to be formed. Furthermore, the external electrodes105made of, for example, solder or the like are welded to upper surfaces of the wirings104. A rear surface of the semiconductor wafer100having such a configuration is attached to an upper surface of a dicing sheet106.

With reference toFIG. 6B, next, the semiconductor device parts102are separated from each other by using a rapidly rotating blade107to cut the wafer100. The semiconductor wafer100and the insulating layer101are completely cut by the blade107. The separated semiconductor device parts102become semiconductor devices, respectively.

FIG. 6Cshows a cross-section of a semiconductor device108manufactured by the above steps. It is clear fromFIG. 6Cthat a planar size of the semiconductor device108is approximately the same as that of a semiconductor substrate109. The planar size of the semiconductor device108is, for example, about 5 mm×5 mm, which is very small.

However, in recent semiconductor devices, an operating frequency is increased for high-speed signal processing, and a heat release value is increased. Meanwhile, in the semiconductor device described above, since the size of the entire device is small, a surface area thereof is too small to obtain sufficient heat radiation properties. Accordingly, problems such as characteristic deterioration and destruction have occurred due to a rapid increase in a temperature of the semiconductor device along with operations thereof.

As a method for solving the above problems, there is a method for releasing heat from the semiconductor device through conductive patterns formed to be partially wide on a mounting substrate side on which the semiconductor device is mounted. However, by use of the above method, the conductive patterns on the mounting substrate side are formed to be wide. Then, an area of the mounting substrate, which is practically required for mounting the semiconductor device, is increased. As a result, there is a problem that packaging density is lowered.

Furthermore, in the manufacturing method described above, chipping occurs in the dicing step using the blade. As a result, there is a problem that a crack is generated in the semiconductor substrate109of each of the semiconductor device parts102. If this crack is large, characteristics of the semiconductor device are deteriorated to cause failures. Moreover, even if the crack is small, there is caused no performance failure. However, in the case where the semiconductor device108is the WLP, sides of the semiconductor substrate109are exposed to result in poor appearance.

SUMMARY OF THE INVENTION

The present invention has been made in consideration for the foregoing problems. It is a main object of the present invention to provide a semiconductor device having improved heat radiation properties and a manufacturing method thereof.

A semiconductor device of the present invention is including a semiconductor substrate having a first principal surface, on which electrodes electrically connected to circuit elements are formed, and a second principal surface facing the first principal surface; and a radiator which is mounted on the second principal surface, and which has the same planar size as that of the semiconductor substrate.

A method for manufacturing a semiconductor device of the present invention is including the steps of: preparing a semiconductor wafer which has a first principal surface, on which electrodes electrically connected to circuit elements are formed, and a second principal surface facing the first principal surface, and which has a plurality of semiconductor device parts formed thereon, which are defined by dicing lines; attaching the semiconductor wafer to a dicing sheet with a radiator plate interposed therebetween, and separating the semiconductor device parts from each other by dicing the semiconductor wafer and the radiator plate.

Furthermore, a method for manufacturing a semiconductor device of the present invention is including the steps of preparing a semiconductor wafer which has a first principal surface, on which electrodes electrically connected to circuit elements are formed, and a second principal surface facing the first principal surface, and which has a plurality of semiconductor device parts formed thereon, preparing a dicing sheet which has first and second sheets stacked with a first adhesion layer interposed therebetween, and which has an uneven adhesion surface between the sheets, attaching the semiconductor wafer to a surface of the first sheet of the dicing sheet with a second adhesion layer interposed therebetween, individually separating the semiconductor device parts by performing dicing so as to cut at least the semiconductor wafer and the first sheet, and separating the first sheet bonded to the semiconductor device part from the second sheet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, preferred embodiments of the present invention will be described in detail below.

First Embodiment

First, with reference toFIGS. 1A and 1B, a configuration of a semiconductor device10of this embodiment will be described.FIG. 1Ais a cross-sectional view of the semiconductor device10, andFIG. 1Bis a perspective view thereof.

With reference toFIGS. 1A and 1B, the semiconductor device10includes: a semiconductor substrate11; a heat sink17(radiator) mounted on an upper surface (a second principal surface) of the semiconductor substrate11; wirings14formed on a lower surface (a first principal surface) of the semiconductor substrate11; and the like.

The semiconductor substrate11is made of, for example, a semiconductor material such as silicon, and circuit elements are formed therein by a diffusion step. For example, a bipolar transistor, a MOSFET, a diode, a memory and the like are formed in the semiconductor substrate11. A thickness of the semiconductor substrate11is, for example, about 25 μm to 500 μm (for example, about 50 μm). In this embodiment, the semiconductor substrate11is reinforced by mounting thereon the heat sink17made of, for example, a metal such as copper. Thus, the thickness of the semiconductor substrate11can be set as small as about 50 μm. A planar size of the semiconductor substrate11is, for example, about 0.5 mm×0.5 mm to 10 mm×10 mm.

The heat sink17is mounted on the upper surface of the semiconductor substrate11, and a planar size thereof is approximately the same as that of the semiconductor substrate11. Moreover, the heat sink17has a thickness of 500 μm to 2 mm, and may be formed to be thicker than the semiconductor substrate11. The heat sink17is fixed to the upper surface of the semiconductor substrate11by use of an insulating adhesive or the like. Note that the heat sink17having grooves18formed therein can be fabricated by extruding a metal such as copper.

Furthermore, a preferable material of the heat sink17is a material having a thermal conductivity higher than that of the semiconductor substrate11. For example, a metal such as copper and aluminum is suitable as the material of the heat sink17. Here, a thermal conductivity of silicon that is the material of the semiconductor substrate11is 168 [W/m/K], a thermal conductivity of copper is 390 [W/m/K], and a thermal conductivity of aluminum is 236 [W/m/K]. As described above, by adopting the material having a high thermal conductivity as the heat sink17, heat radiation properties of the semiconductor substrate11can be improved.

Still furthermore, as the material of the heat sink17, resin can also be adopted. Generally, resin is inferior to metal in the thermal conductivity. However, by adopting the heat sink17made of resin, a surface area of the entire semiconductor device10is increased. Thus, the heat radiation properties thereof are improved. Furthermore, by using resin filled with fillers made of alumina or the like to form the heat sink17, the heat radiation properties can be further improved. Moreover, as the heat sink17, a dicing sheet used in the steps of manufacturing a semiconductor device can also be adopted. This will be described in detail later.

With reference toFIG. 1B, in the heat sink17, the grooves18are formed from a surface (upper surface) thereof which does not come into contact with the semiconductor substrate11. A width of each of the grooves18is about 20 μm to 100 μm, and a depth thereof is within a range that the groove18does not penetrate the heat sink17(for example, 400 μm or more and less than 2 mm). Furthermore, the grooves18are extended parallel with sides of the semiconductor substrate11, and are formed linearly and continuously from a front end of the semiconductor substrate11to a rear end thereof. Here, the grooves18may be provided in a lattice pattern. In this case, a surface area of the heat sink17is further increased, and a heat radiation effect can be improved.

On the lower surface of the semiconductor substrate11, electrodes13electrically connected to internal elements (active regions) are formed. The lower surface of the semiconductor substrate11, except for portions in which the electrodes13are formed, is covered with an insulating layer12. The insulating layer12is made of, for example, a nitride film or a resin film. Furthermore, lower surfaces of the electrodes13are exposed to a lower side from the insulating layer12.

On a lower surface of the insulating layer12, the wirings14are formed, which come into contact with the electrodes13. Here, the electrodes13are provided in a peripheral portion of the semiconductor device10, and the wirings14are extended toward the inside from the peripheral portion. A portion of each of the wirings14is formed into a pad shape, and an external electrode15is welded to the pad-shaped portion. The external electrodes15are made of a conductive adhesive such as solder. By providing the wirings14as described above, the electrodes13arranged close to each other can be rearranged as the external electrodes15which are to be away from each other. Furthermore, the wirings14, except for regions where the external electrodes15are formed, are covered with a covering layer16made of an insulating material such as resin.

Note that, when thermal expansion coefficients of the semiconductor substrate11and the heat sink17are significantly different from each other, warpage is likely to occur in the semiconductor substrate11. For this reason, the materials, thicknesses, and the like of the insulating layer12, the covering layer16and the wirings14are determined so as to set the upper and lower surfaces of the semiconductor substrate11to have the same thermal expansion coefficient. For example, when the heat sink17is formed to have a thickness of about 30 μm, each of the wirings14is also formed to have a thickness of about 30 μm. Moreover, a density of the grooves18may be controlled according to patterning of the wirings14. Furthermore, when the heat sink17is formed to have a thickness of about 30 μm, and when each of the wirings14is formed to have a thickness of about 15 μm, the grooves18may be formed so as to increase the density thereof. Specifically, the grooves18are formed so as to set a volume of the wiring14and a volume of the heat sink17to be the same.

Second Embodiment

In this embodiment, with reference toFIGS. 2 to 4, description will be given of a method for manufacturing the semiconductor device having the configuration described in the first embodiment.

With reference toFIG. 2A, a semiconductor wafer22includes an upper surface (a first principal surface), on which electrodes13and the like are formed, and a flat lower surface (a second principal surface). Furthermore, on the semiconductor wafer22, a number of (for example, a few hundred of) semiconductor device parts24are formed in a matrix pattern. The semiconductor device parts24are defined by dicing lines27which are provided in a lattice pattern. Here, each of the semiconductor device parts24is a part to become one semiconductor device. In each of the semiconductor device parts24, predetermined circuit elements (active regions) are formed inside the semiconductor wafer22, and the electrodes13connected to the elements are arranged in a peripheral portion of the semiconductor device parts24. The semiconductor wafer22made of a semiconductor material such as silicon has a thickness of, for example, about 50 μm to 500 μm.

With reference toFIG. 2B, a radiator plate19is made of a metal such as copper and aluminum having a thickness of about 500 μm to 2 mm, and a planar size thereof is the same as that of the semiconductor wafer22. An upper surface (a first principal surface) of the radiator plate19is a flat and smooth surface which comes into contact with the lower surface of the semiconductor wafer22, and grooves18are formed in a lower surface (a second principal surface) thereof. A direction in which the grooves18are extended is preferably in parallel with the dicing lines27described above. Accordingly, the direction in which the grooves18are extended can be set parallel with sides of the semiconductor device part24. Thus, external appearance of the device can be improved. Furthermore, by superposing the grooves18and the dicing lines27, the radiator plate19can be cut only by removing thick portions of the radiator plate19, in which the grooves18are not formed, in a dicing step.

The semiconductor wafer22and the radiator plate19are bonded to each other by use of an adhesive such as insulating resin. Specifically, after the adhesive is applied to the upper surface of the radiator plate19or the lower surface of the semiconductor wafer22, the wafer and the plate are attached and bonded to each other.

With reference toFIG. 2C, in each of the semiconductor device parts24, the electrodes13connected to the elements formed inside the semiconductor wafer22are formed in the peripheral portion thereof. The upper surface of the semiconductor wafer22is covered with an insulating layer12made of resin or the like, in a state where the electrodes13are exposed. Moreover, on an upper surface of the insulating layer12, wirings14are formed, which are extended toward a center portion of each semiconductor device part24from the peripheral portion thereof. Furthermore, a external electrode15made of solder or the like is welded to an upper surface of each of the wirings14, which is formed into a pad shape. Moreover, the upper surface of the insulating layer12, except for portions in which the external electrodes15are formed, is entirely covered with a covering layer16. The wirings14are covered with the covering layer16.

Note that, when thermal expansion coefficients of a semiconductor substrate11and the radiator plate19are significantly different from each other, warpage is likely to occur in the semiconductor substrate11. For this reason, materials, thicknesses, and the like of the insulating layer12, the covering layer16and the wirings14are determined so as to set the upper and lower surfaces of the semiconductor substrate11to have the same thermal expansion coefficient. For example, when the radiator plate19is formed to have a thickness of about 30 μm, each of the wirings14is also formed to have a thickness of about 30 μm. Moreover, a density of the grooves18may be controlled according to the patterning of the wirings14. Furthermore, when the radiator plate19is formed to have a thickness of about 30 μm, and when each of the wirings14is formed to have a thickness of about 15 μm, the grooves18may be formed so as to increase the density thereof. Specifically, the grooves18are formed so as to set a volume of the wiring14and a volume of the radiator plate19to be the same.

With reference toFIGS. 3A to 3C, next, the radiator plate19and the semiconductor wafer22are diced after being attached to a dicing sheet21.FIG. 3Ais a cross-sectional view showing this step,FIG. 3Bis a perspective view thereof, andFIG. 3Cis a cross-sectional view after the dicing is performed.

With reference toFIG. 3A, the upper surface of the radiator plate19is attached to the semiconductor wafer22, and the lower surface of the radiator plate19is attached to the dicing sheet21. The dicing sheet21is made of a soft and elastic resin material, and has a thickness of, for example, about 50 μm to 100 μm. Moreover, for the dicing sheet21, a material through which at least ultraviolet rays are transmitted well is preferable. Since the ultraviolet rays are transmitted through the dicing sheet21, the semiconductor device parts24can be easily separated from the dicing sheet21by performing ultraviolet irradiation from below the dicing sheet21in a subsequent step to reduce adhesive force of an adhesion layer25.

The adhesion layer25is formed so as to cover the entire upper surface of the dicing sheet21, and has a function of attaching the radiator plate19to the dicing sheet21. The adhesion layer25has a thickness of, for example, about 20 μm to 40 μm. Moreover, as the adhesion layer25, a material having adhesion reduced when hardened by external force applied thereto is preferable. As the external force, there are, for example, heat and light rays having a predetermined wavelength (for example, the ultraviolet rays). As an example, a resin material having adhesion reduced when hardened by irradiation of ultraviolet rays is suitable as the material of the adhesion layer25. The dicing sheet21having such a type of adhesion layer25coated to its surface is generally called a UV sheet.

With reference toFIG. 3B, next, the semiconductor wafer22and the radiator plate19are diced at the same time to individually separate the semiconductor device parts24. Here, a peripheral part of the dicing sheet21having the semiconductor wafer22and the like attached thereto is mechanically supported by a wafer ring23. Here, the wafer ring23is obtained by processing a metal plate made of stainless steel or the like, for example, into a ring shape, and an inside diameter thereof is larger than a diameter of the semiconductor wafer22.

Since the semiconductor device parts24are arranged in the matrix pattern, dicing is performed a number of times along the dicing lines27in one direction by use of a blade26. Thereafter, the wafer ring23is rotated 90°, and the dicing is performed again a number of times along the dicing lines27.

With reference toFIG. 3C, in this step, the dicing is performed so as to cut at least the covering layer16, the insulating layer12, the semiconductor wafer22and the radiator plate19. In order to surely perform the cutting, the dicing may actually be performed so as to cut the adhesion layer25and to partially cut the dicing sheet21.

In this embodiment, by providing the radiator plate19between the semiconductor wafer22and the dicing sheet21, breakage of the semiconductor wafer22is prevented. To be more specific, the dicing sheet21is made of a soft resin material. Accordingly, when pressing force of the blade26is applied to the semiconductor wafer22from above, the dicing sheet21below a portion with which the blade26comes into contact is sunk. Then, there is a risk that breakage is caused by a bending stress acting on the semiconductor wafer22. In this embodiment, the radiator plate19which is harder than the dicing sheet21, and which has good mechanical strength is provided on the lower surface of the semiconductor wafer22. Thus, the bending stress described above is reduced by the radiator plate19. As a result, the cracking of the semiconductor wafer22is prevented.

Furthermore, in this embodiment, the grooves18of the radiator plate19are positioned below the dicing lines27positioned between the semiconductor device parts24. Thereby, the radiator plate19is divided only by removing the thick portions of the radiator plate19by dicing, in which portions the grooves18are not provided. When the radiator plate19made of a metal such as copper is diced by use of the dicing blade26, the dicing blade26is easily worn away. Thus, by performing the dicing in the portions where the grooves18are provided, portions of the radiator plate19to be cut become thinner. As a result, there is an advantage that wear of the blade26can be reduced.

By this step, the individual semiconductor device parts24are obtained from the semiconductor wafer22. The individual semiconductor device parts24are also electrically separated from each other. Thus, electrical characteristics and the like of the individual semiconductor device parts24can be tested by connecting probes to the external electrodes15.

With reference toFIG. 4, next, the semiconductor device parts24are separated from the dicing sheet21.FIG. 4is a cross-sectional view showing this step.

With reference toFIG. 4, in this step, ultraviolet rays29are irradiated from below the dicing sheet21. Since the dicing sheet21is made of a resin material highly transparent to the ultraviolet rays, the ultraviolet rays29are transmitted through the dicing sheet21and reach the adhesion layer25. The adhesion layer25irradiated with the ultraviolet rays29is hardened, and the adhesive force thereof is reduced. Thus, a situation that facilitates separation of the semiconductor device parts24is created.

Next, by use of an unillustrated adsorption collet, the semiconductor device parts24are separated from the dicing sheet21. Since the adhesive force of the adhesion layer25is reduced by the ultraviolet irradiation described above, the semiconductor device parts24can be easily separated.

In this step, the radiator plate19is attached to the lower surface of the semiconductor substrate11in each of the semiconductor device parts24. Thus, cracking and chipping of the semiconductor substrate11in the separation step can be prevented. To be more specific, when the unillustrated adsorption collet is used to lift up the semiconductor device part24positioned in the center, the dicing sheet21is slightly lifted up along therewith. The reason why the dicing sheet21is lifted up is because the adhesive force of the adhesion layer25is slightly remaining.

When the semiconductor device part24in the center is further lifted up in the above-described state, the lifted semiconductor device part24in the center may come into contact with the semiconductor device parts24on both sides thereof. In the conventional case, the semiconductor substrates11are attached directly to the dicing sheet21. Thus, chipping or cracking of the fragile semiconductor substrates11is caused by contact therebetween. In this embodiment, the radiator plate19made of the metal is attached to the lower surface of the semiconductor substrate11. Thereby, even if the semiconductor device parts24adjacent to each other come into contact with each other along with picking up thereof, the metal radiator plates19come into contact with each other. Accordingly, the semiconductor substrates11are not damaged. Moreover, since the radiator plates19are made of highly ductile metal, the radiator plates19are hardly damaged by the contact therebetween. Even if the radiator plates19are damaged, there is hardly any problem in terms of appearance.

By the above steps, a semiconductor device10shown inFIGS. 1A and 1Bis manufactured. Moreover, each of the semiconductor device parts24separated from the dicing sheet21is carried to be mounted on a mounting substrate or the like by a reflow step of melting the external electrodes, and the like.

Third Embodiment

With reference toFIGS. 5A to 5C, description will be given of a method for manufacturing a semiconductor device according to another embodiment. The manufacturing method of this embodiment is different from that of the second embodiment in a point that a part of a dicing sheet is left as a radiator in the semiconductor device. In the other points, this embodiment is the same as the second embodiment described above.

With reference toFIG. 5A, first, a semiconductor wafer22having a number of semiconductor device parts24formed thereon by a diffusion step and the like is attached to a dicing sheet21with a second adhesion layer20interposed therebetween.

The dicing sheet21includes a first sheet31and a second sheet32, which are bonded to each other with a first adhesion layer28interposed therebetween. A boundary surface between the first and second sheets31and32is set to be an uneven surface. Here, the uneven surface has a cross-section with rectangular concaves and convexes. Accordingly, on the boundary surface between the sheets, the second sheet32is formed to be concave in a portion where the first sheet31is formed to be convex, and the second sheet32is formed to be convex in a portion where the first sheet31is formed to be concave. The dicing sheet21has a thickness of, for example, about 100 μm to 200 μm.

An adhesion surface between the first and second sheets31and32has an uneven shape. Accordingly, adhesion between the sheets is improved. Thus, separation between the sheets in the middle of manufacturing can be prevented. Furthermore, since a rear surface of the first sheet31, which forms a part of the device as a radiator, has the uneven shape, a surface area is increased to improve a heat radiation effect.

The first sheet31is an upper layer of the dicing sheet21, and an upper surface thereof is attached to a rear surface of the semiconductor wafer22with the second adhesion layer20interposed therebetween. The first sheet31is used as the radiator in the semiconductor device. Thus, for improvement in thermal conductivity, the first sheet31may be made of resin in which inorganic fillers such as silica are mixed. A thickness of the first sheet31may be about half that of the dicing sheet21, and is, for example, about 50 μm to 100 μm.

The second sheet32forms a lower layer of the dicing sheet21. A preferable material of the second sheet32is a resin material through which light rays (for example, ultraviolet rays) irradiated for reducing adhesive force of the first adhesion layer28are transmitted well. By using the resin material described above to form the second sheet32, the light rays irradiated from below the dicing sheet21can easily reach the first adhesion layer28. A thickness of the second sheet32may be about 50 μm to 100 μm, which is the same as that of the first sheet31.

The second adhesion layer20has a function of bonding the first sheet31, which forms a part of the semiconductor device as the radiator, to the semiconductor wafer22. As the second adhesion layer20, a normal insulating adhesive resin can be adopted. In order to maintain adhesive force also in the next step of ultraviolet irradiation and subsequent steps, the second adhesion layer20is required not to have the adhesive force reduced by the ultraviolet irradiation.

As the first adhesion layer28, a resin material having adhesive force reduced by heating or light irradiation is preferable. By using the resin material described above to form the first adhesion layer28, the first sheet31, which forms a part of the semiconductor device, and the second sheet32, which functions as a supporting member for dicing, are easily separated from each other.

With reference toFIG. 5B, the semiconductor wafer22is divided by dicing so as to separate the semiconductor device parts24from each other. Details of the dicing in this step are the same as those in the second embodiment described above. Here, the dicing is performed so as to divide at least a covering layer16, a insulating layer12, the semiconductor wafer22, the second adhesion layer20and the first sheet31. Furthermore, in order to surely perform the dicing, the dicing may be performed until the first adhesion layer28and part of the second sheet32are divided.

With reference toFIG. 5C, next, each of the semiconductor device parts24is separated from the dicing sheet21. First, ultraviolet rays29are irradiated from below the dicing sheet21. Accordingly, the irradiated ultraviolet rays29are transmitted through the second sheet32, and reach the first adhesion layer28. Thereby, the first adhesion layer28is hardened and the adhesive force thereof is reduced. Moreover, in the case where the first adhesion layer28has a property that the adhesive force is reduced by heating, the adhesive force of the first adhesion layer28is reduced by heat treatment. Meanwhile, the adhesive force of the second adhesion layer20is not changed even if the ultraviolet rays29reach the second adhesion layer20.

Next, by use of an unillustrated adsorption collet or the like, the semiconductor device parts24are separated (picked up) from the dicing sheet21. Here, the first sheet31, which is attached to the lower surface of a semiconductor substrate11with the second adhesion layer20interposed therebetween, is also separated from the dicing sheet21as a part of the semiconductor device part24.

Moreover, even if the semiconductor device parts24adjacent to each other come into contact with each other in the pick up step described above, the first sheets31made of the resin material at the bottoms come into contact with each other. Thus, the semiconductor substrates11do not come into contact with each other. As a result, cracking and damage of the semiconductor substrates11in this step are suppressed.

By the above steps, the semiconductor device having the radiator made of the resin material is manufactured.

Note that, when thermal expansion coefficients of the semiconductor substrate11and the first sheet31are significantly different from each other, warpage is likely to occur in the semiconductor substrate11. For this reason, materials, thicknesses and the like of the insulating layer12, the covering layer16and wirings14are determined so as to set upper and lower surfaces of the semiconductor substrate11to have the same thermal expansion coefficient and to have the same thermal expansion coefficient as that of the first sheet31. For example, the insulating layer12and the covering layer16are formed by use of the same material as that of the first sheet31.

According to the semiconductor device of the preferred embodiments of the present invention, since the radiator is mounted on the principal surface of the semiconductor substrate, a surface area of the entire device is increased. Thus, heat radiation properties can be improved. Furthermore, when a material having a thermal conductivity higher than that of the semiconductor substrate is adopted as the radiator, heat generated by operations of the circuit elements formed in the semiconductor substrate is actively discharged to the outside through the radiator. Therefore, even if high-speed processing circuits are built into the semiconductor device, an increase in a temperature of the semiconductor device can be suppressed.

According to the method for manufacturing a semiconductor device of the preferred embodiments of the present invention, after the semiconductor wafer is attached to the dicing sheet with the radiator plate interposed therebetween, the semiconductor device parts formed on the semiconductor wafer are individually separated. Therefore, the radiator plate relaxes a bending stress acting on the semiconductor wafer in the dicing step. As a result, cracking of the semiconductor wafer is suppressed.

Furthermore, in the preferred embodiments of the present invention, the semiconductor device parts are separated from the dicing sheet in a state where the radiator plates made of a metal or the like are attached to the semiconductor device parts. Therefore, even if the separated semiconductor device parts come into contact with the other adjacent semiconductor device parts, the radiator plates in the bottoms come into contact with each other. As a result, the semiconductor substrates in the semiconductor device parts do not come into contact with each other, and occurrence of chipping is prevented.

Still Furthermore, according to the method for manufacturing a semiconductor device of the preferred embodiments of the present invention, the semiconductor device is manufactured by use of the dicing sheet including the first and second sheets bonded by the uneven adhesion surface. Therefore, the first sheet can be left on the semiconductor device side by separating the first and second sheets after the semiconductor wafer is divided into the individual semiconductor device parts by use of the dicing sheet. As a result, the first sheet that is a part of the dicing sheet can be easily mounted, as the radiator, on the semiconductor device.