JP2010040662A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, which improves position precision of sticking and reduces thickness variance of an adhesive even when a semiconductor wafer and a substrate with optical transparency are stuck together. <P>SOLUTION: In a step of sticking the semiconductor wafer and coating substrate together, the coating substrate is bonded to a correction substrate to correct curvature of the coating substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device of a sensor CSP (Chip Scale Package or Chip Size Package) type.

  With recent miniaturization and high performance of mobile phones, camera modules used in mobile phones are becoming increasingly compatible with high pixels and have a low profile. In addition, downsizing of sensor components built in camera modules for mobile phones is also required. Conventionally, a wire bond method, a flip chip method, or the like has been employed for mounting a sensor, but in recent years, a method for mounting a sensor as a CSP (Chip Scale Package or Chip Size Package) has attracted attention. This method enables high-density mounting because the sensor is formed to be ultra-small and thin, close to the chip size. In addition, this method can use a conventional surface mounting technique for mounting a sensor on a printed circuit board. In the following, such a sensor is referred to as a sensor CSP.

  There are various methods for the sensor CSP. When the sensor is manufactured in a wafer state (hereinafter referred to as a wafer level CSP), a method of forming wiring on the side of the package and each sensor CSP (that is, for each sensor chip). There is known a TSV (Through Silicon Via) method in which a through hole (via hole) is provided in a semiconductor device.

  An example of a TSV type sensor CSP will be described with reference to FIG. FIG. 1A shows a cross-sectional view of a TSV sensor CSP100. The sensor CSP 100 includes a semiconductor element substrate 101 on which semiconductor elements are formed, an adhesive 102 applied on the main surface of the semiconductor element substrate 101, a cover glass 103 attached to the semiconductor element substrate 101 via the adhesive 102, The TSV 104 that penetrates the semiconductor element substrate 101 from the main surface to the back surface, the back surface wiring 105 formed on the back surface of the semiconductor element substrate 101, the back surface sealing layer 106 that covers the back surface wiring 105, and the back surface wiring 105 are connected to the TSV 104. Terminal 107. In such a configuration, a main surface wiring (not shown) formed on the main surface of the semiconductor chip 101 is connected to the terminal 107 via the TSV 104 and the back surface wiring 105.

Next, the structure of the camera module using the sensor CSP 100 will be described with reference to FIG. FIG. 1B shows a cross-sectional view of a camera module 200 using the sensor CSP 100. The camera module 200 includes a substrate 201 on which a pad (not shown) on which a circuit and the sensor CSP 100 are mounted is formed on the main surface, a sensor CSP 100 mounted on the pad, a casing 202 surrounding the sensor CSP 100, a sensor The IR cut glass 203 is fixed to the housing 202 so as to face the cover glass 103 of the CSP 100, and the two optical lenses 204 are fixed to the upper portion of the IR cut glass by the housing 202. Since the IR cut glass 203 has a structure in which a thin film of about 50 layers is coated on the surface of a glass substrate, transmission of light in the infrared region can be prevented. Such a 50-layer thin film structure is formed by alternately depositing a low refractive index (for example, silicon dioxide: SiO ₂ ) and a high refractive index (for example, tantalum pentoxide: Ta ₂ O ₅ ) as a dielectric film on the surface of the glass substrate. It is the structure which forms into a film.

  In recent years, it has been studied to apply the above-described coating process to the cover glass 103 of the sensor CSP 100 and to remove the IR gut glass 203 in response to a request for reducing the height of the camera module 200.

Note that Patent Document 1 describes a method in which a hot melt type adhesive is used and the wafer and the reinforcing substrate are bonded so that bubbles do not enter the adhesive.
JP2007-109999

  However, since the cover glass is as thin as 0.3 to 0.5 mm, warpage is generated by the above-described coating process. Such warpage of the cover glass is caused by the order of vapor deposition (low refractive index film and vapor deposition order of high refractive index), variation in film thickness, etc., and thus the warpage is completely eliminated even if coating is applied to both surfaces of the glass substrate. It is difficult. For example, when the cover glass has a diameter of 8 mm and a thickness of 0.3 mm, when the above-described coating is applied to both sides of the cover glass, the coated cover glass (hereinafter simply referred to as coating glass) is coated with the coating glass. A warpage of about 0.1 mm occurs on the circumference with respect to the center. When such warpage occurs in the coating glass, there arises a problem that it becomes difficult to bond the coating glass and the semiconductor wafer on which the semiconductor element is formed.

  Using a film-like adhesive and applying a predetermined pressure to the coating glass when the coating glass and the semiconductor wafer are bonded to each other can be bonded, but the coating glass warps and is positioned between the coating glass and the semiconductor wafer. Deviation occurs. In addition, even if liquid resin adhesive is used and the coating glass and semiconductor wafer are bonded together with a predetermined pressure applied to the coating glass to correct the warp, the adhesive will protrude from between the coating glass and the semiconductor wafer. End up. In addition, when a liquid resin adhesive is used, there is a problem that the thickness variation of the adhesive becomes large.

  The present invention has been made in view of the above circumstances, and in the case of bonding a semiconductor wafer and a light-transmitting substrate, the positional accuracy of the bonding is improved and the thickness variation of the adhesive is reduced. A method for manufacturing a semiconductor device is provided.

  In order to solve the above-described problems, a method of manufacturing a semiconductor device according to the present invention includes a semiconductor wafer preparation step of preparing a semiconductor wafer including a plurality of semiconductor element structures, and a coating film on a light-transmitting substrate having optical transparency. A method for manufacturing a semiconductor device, comprising: a coating substrate preparation step for preparing a formed coating substrate; and a bonding step for bonding the coating substrate and the semiconductor wafer. The bonding step includes applying the coating substrate to the correction substrate. And a warp correction step of correcting the warpage of the coated substrate.

  According to the method for manufacturing a semiconductor device of the present invention, in the bonding process between the semiconductor wafer and the coating substrate, the coating substrate is bonded to the correction substrate to correct the warpage of the coating substrate. The thickness variation of the adhesive can be reduced.

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

  A method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flow diagram of the manufacturing process of the semiconductor device, FIG. 3 is a cross-sectional view for each manufacturing process of the semiconductor device, and FIG. 4 is the temperature in the manufacturing process of the semiconductor device, and the coated glass on the semiconductor wafer at the time of bonding. It is a time chart which shows the time change of the distance of the amount of pressing of a board | substrate, and the cover glass (henceforth only coating glass) with which the semiconductor wafer was coated. FIG. 5A is a cross-sectional view of a semiconductor device manufactured by the method of manufacturing a semiconductor device of this embodiment, and FIG. 5B is a cross-sectional view of a glass substrate covered with a dielectric film. .

  First, a semiconductor wafer 11 having a plurality of semiconductor elements formed on a semiconductor substrate such as silicon is prepared. (FIG. 2: Step S1, FIG. 3 (a)). For example, as shown in FIG. 5A, the semiconductor wafer 11 includes a semiconductor element substrate 21 in which a semiconductor element region (for example, a PN diode region made of a PN junction) is formed, and the semiconductor element substrate 21 as a main surface. A semiconductor chip comprising a TSV 22 penetrating from the back surface to the back surface, a back surface wiring 23 formed on the back surface of the semiconductor element substrate 21, a back surface sealing layer 24 covering the back surface wiring 23, and a terminal 25 connected to the TSV 22 via the back surface wiring 23. Reference numeral 26 denotes a wafer on which a plurality of wafers are formed. An electrode pad (not shown) such as aluminum may be formed on the semiconductor element substrate 21.

  Next, an adhesive (first adhesive) 12 is applied on the semiconductor wafer 11 (FIG. 2: step S2, FIG. 3 (b)). For example, the adhesive may be an epoxy resin. In addition, the adhesive application process may be an application using a spin coating method, a printing method, or a spray coating method in which the epoxy resin is applied by centrifugal force generated by high-speed rotation of the semiconductor wafer 11.

Next, a light-transmitting substrate 13 (hereinafter referred to as coating glass) in which a thin film (that is, a coating film) is coated on both surfaces of the glass substrate is prepared (FIG. 2: Step S3). The prepared coating glass 13 and the semiconductor wafer 11 coated with the adhesive 12 are arranged in a bonding apparatus (not shown) separated by a predetermined distance. As shown in FIG. 4, the distance between the semiconductor wafer 11 and the coating glass 13 is set to 0.3 to 1.0 mm. As shown in FIG. 5B, the coating glass 13 has a structure in which a coating layer 32 composed of about 50 thin films is formed on a glass substrate 31. Therefore, the coating glass 13 can prevent transmission of light in the infrared region. The coating layer 32 may have a structure in which vapor deposition materials having a low refractive index (for example, silicon dioxide: SiO ₂ ) and a high refractive index (for example, tantalum pentoxide: Ta ₂ O ₅ ) are alternately deposited. Further, the coating layer 32 may be provided only on one side of the glass substrate 31. By the coating, the coating glass 13 has a warp as shown in FIG.

  After the semiconductor wafer 11 and the coating glass 13 are arranged in the bonding apparatus, the temperature in the bonding apparatus rises to a predetermined temperature by a predetermined heating. Further, the temperature of the adhesive 12 rises to a predetermined temperature (that is, a semi-curing temperature) as the temperature in the bonding apparatus rises. Specifically, as shown in FIG. 4, heating is performed until the adhesive 12 reaches about 120 degrees Celsius (120 ° C.). Then, the temperature of the adhesive 12 is maintained at about 120 ° C. for about 10 minutes. The adhesive 12 changes to a semi-cured state when reaching about 120 ° C. (FIG. 2: step S4). The semi-cured state is a state before the adhesive 12 is completely cured, and the coating glass 13 can be temporarily fixed and the coating glass 13 is pressed against the semiconductor wafer 11 with a predetermined pressing amount. No. 12 is a cured state in which the adhesive 12 does not protrude or the thickness of the adhesive 12 does not vary. In addition, this process is called a 1st heating process.

  After heating for 10 minutes at 120 ° C., the coating glass 13 is placed on the semiconductor wafer 11 via the adhesive 12 (FIG. 2: step S5, FIG. 3 (c)). The coating glass 13 state in this step is temporarily fixed to the adhesive 12 because the adhesive 12 is in a semi-cured state, and further the position of the coating glass 13 (position with respect to the semiconductor wafer 11 and its warpage) by a predetermined press described later. Is in a state where it can be adjusted. In FIG. 3C, the central part of the coating glass 13 is arranged with the upper body warped from the surroundings, but the coating glass 13 is arranged in reverse and the central part is more adhesive than the surroundings. You may arrange | position in the state close | similar to 12 (namely, the state where the circumference | surroundings went up).

  After the coating glass 13 is arranged, the temperature in the laminating apparatus rises again to a predetermined temperature (that is, a curing temperature) by predetermined heating. As the temperature rises, the pressing amount of the semiconductor wafer 11 against the coating glass 13 increases to a predetermined pressing amount (FIG. 2: step S6, FIG. 3 (d)). Specifically, as shown in FIG. 4, heating is performed until the adhesive 12 reaches about 140 ° C., and the state of 140 ° C. is maintained for about 5 minutes. Further, the pressing amount is increased until the pressing amount of the co-semiconductor wafer 11 against the coating glass 13 reaches 0.1 MPa (megapascal), and the pressing by 0.1 MPa is maintained for about 5 minutes. The adhesive 12 changes to a fully cured state when the temperature reaches 140 ° C. The fully cured state is a state in which the occurrence of displacement of the coating glass 13 bonded to the adhesive 12 is eliminated and the bonding position is determined. After the pressing state at 140 ° C. and 0.1 MPa is maintained for 5 minutes, the temperature and the pressing amount gradually decrease. In addition, this process is called a 2nd heating process.

  The warp of the coating glass 13 is corrected by applying a predetermined pressure (0.1 MPa) to the coating glass 13 in the above-cured state of the adhesive 12 (FIG. 3E). Since the pressure is gradually applied from the semi-cured state of the adhesive 12 (that is, the position and the warp of the coating glass 13 can be adjusted), it becomes possible to correct the warp of the coating glass 13 on the adhesive 12. . From the above-described steps, in this embodiment, the semiconductor wafer 11 is also used as a correction substrate for correcting the warp of the coating glass 13.

  When the temperature of the adhesive 12 returns to room temperature, additional heat treatment is performed on the semiconductor wafer 11 on which the coating glass 13 is bonded by another heating device or the like (FIG. 2: Step S7). For example, additional heating at about 160 ° C. for 1 hour may be performed. Such additional heating completes the complete curing of the adhesive 12.

  After the additional heat treatment, dicing is performed on a predetermined dicing region of the semiconductor wafer 11 to form the semiconductor wafer 11 into chips. Specifically, a sensor CSP 20 as shown in FIG. 5A is formed. As shown in FIG. 5A, the coating glass 13 is bonded to the semiconductor wafer 11 through the adhesive 12 without warping.

  As described above, according to the manufacturing method of the semiconductor device of this embodiment, in the bonding process of the semiconductor wafer 11 and the coating glass 13, the coating glass 13 is placed on the semiconductor wafer 11 via the semi-cured adhesive 12. Further, a predetermined pressure is applied until the adhesive 12 is fully cured, thereby improving the positional accuracy of the bonded state of the semiconductor wafer 11 and the coating glass 13 and reducing variations in the thickness of the adhesive. be able to.

  In the first embodiment, the cured state of the adhesive is divided into two stages (semi-cured state and main-cured state), and when the adhesive is in the semi-cured state, the coating glass is placed on the semiconductor wafer, Although the positioning of the coating glass is sometimes performed, the coating glass may be bonded to the semiconductor wafer via an adhesive without dividing the cured state. Specific examples thereof will be described below with reference to FIGS. The same members as those in the first embodiment are denoted by the same reference numerals.

First, a semiconductor wafer 11 having a plurality of semiconductor elements formed on a semiconductor substrate such as silicon is prepared. (FIG. 6: Step S101, FIG. 7A). The semiconductor wafer 11 has the same structure as that of the first embodiment. As shown in FIG. 5A, the semiconductor element substrate 21, the TSV 22, the back surface wiring 23, the back surface sealing layer 24, and the terminals. Next, the adhesive 12 is applied onto the semiconductor wafer 11 (FIG. 6: step 102, FIG. 7 (b)). As in the first embodiment, the adhesive 12 may be an epoxy resin. In addition, the adhesive application process may be an application using a spin coating method, a printing method, or a spray coating method in which the epoxy resin is applied by centrifugal force generated by high-speed rotation of the semiconductor wafer 11.

  Next, a support substrate 71 is prepared as a correction substrate for correcting the warp of the coating glass 13 (FIG. 6: step S103, FIG. 7C). For example, the support substrate 71 is a substrate made of a material such as glass, ceramic, or resin. In addition, since the support substrate 71 is used for correcting the warp of the coating glass described later, it is desirable that the support substrate 71 be a flat inflexible substrate.

  Next, an auxiliary adhesive (second adhesive) 72 is applied on the support substrate 71 (FIG. 6: step S104, FIG. 7 (d)). For example, the auxiliary adhesive 72 may be a UV curable adhesive. The reason why a UV curable adhesive is used as the auxiliary adhesive 72 is that it becomes possible to easily peel off a coating glass, which will be described later, bonded to the support substrate 71 via the UV curable adhesive. Accordingly, the auxiliary adhesive 72 may be another auxiliary adhesive as long as it can easily peel the coating glass.

  Next, a light-transmitting substrate 13 (hereinafter referred to as coating glass) having a thin film coating on both surfaces of the glass substrate is prepared (FIG. 6: Step S5). The coating glass 13 is the same as that of the first embodiment and has a warp as shown in FIG.

  Next, the coating glass 13 is disposed on the support substrate 71 via the auxiliary adhesive 72. Subsequently, the auxiliary adhesive 72 is irradiated with UV light, and the coating glass 13 is temporarily bonded to the support substrate 71 via the auxiliary adhesive 72 (FIG. 6: Step S106, FIG. 7E). In the temporary bonding process, the coating glass 13 is pressed against the support substrate 71 with a predetermined pressing amount. The warp of the coating glass 13 is corrected by such pressing (FIG. 7 (f)). For example, the pressing amount may be 0.1 MPa. Although the auxiliary adhesive 72 may protrude by pressing, the problem as the sensor CSP does not occur because the auxiliary adhesive 72 is removed by a peeling process described later. In this step, a WSS (Wafer support system) using a sheet-like adhesive can also be used. The process of correcting the warp described above is referred to as a correction bonding process.

  Next, the semiconductor wafer 11 and the support substrate 71 coated with the adhesive 12 so that the coating glass 13 temporarily bonded to the support substrate 71 is opposed to the surface of the semiconductor wafer 11 coated with the adhesive 12. The coating glass 13 temporarily bonded to is placed in a bonding apparatus (not shown). Then, the coating glass 13 is arrange | positioned on the adhesive agent 12 (FIG. 6: step S107, FIG. 8 (a)). In the placement step, the surface of the coating glass 13 that is not bonded to the temporary adhesive 72 is placed facing the semiconductor wafer 11 with the adhesive 12 interposed therebetween.

  Next, the temperature in the bonding apparatus is heated to a predetermined temperature, and accordingly, the adhesive 12 is also heated to the curing temperature. The adhesive 12 is cured by such heating and bonds the semiconductor wafer 11 and the coating glass 13 (FIG. 6: Step S108, FIG. 8B). In the present embodiment, heating to bring the adhesive 12 into a temporarily cured state is not performed as in the first embodiment, and only heating at 140 ° C. for 5 minutes is performed. Such a heating process is referred to as a curing heating process. In this heating step, the coating glass 13 may be pressed against the semiconductor wafer 11 with a predetermined pressing amount.

  Thereafter, similarly to the first embodiment, additional heat treatment is performed at 160 ° C. for 1 hour on the bonded semiconductor wafer 11 using another thermostatic layer. Further, predetermined heat is applied to the temporary adhesive 72, and the support substrate 71 is peeled off from the coating glass (FIG. 6: step 109, FIG. 8C). For example, in the case of a UV curable adhesive having an acrylic resin as a component, the support substrate 71 is peeled from the coating glass 71 by heating at 85 ° C. for 30 minutes or more. Thereafter, dicing is performed on a predetermined dicing region of the semiconductor wafer 11 to form the semiconductor wafer 11 into chips. Specifically, the sensor CSP 20 as shown in FIG. 5A is formed as in the first embodiment.

  In this embodiment, the adhesive 12 is applied on the semiconductor wafer, but may be applied on the coating glass 13. This is because the warping of the coating glass 13 is corrected by temporary bonding with the support substrate 71 via the temporary adhesive 72, so that the bonding is performed with high accuracy even when the adhesive 12 is applied on the coating glass 13. Because it can.

  As described above, in the second embodiment, the coating glass 13 is bonded to the semiconductor wafer 11 after correcting the warp of the coating glass 13, so that the coating glass is bonded to the semiconductor wafer 11 with high accuracy even with a liquid adhesive. Can do. In addition, since heating for the temporarily-cured state as in the first embodiment is not required, the coating glass can be bonded to the semiconductor wafer with high accuracy even in an adhesive that is difficult to generate the temporarily-cured state. It becomes possible.

  In the embodiment described above, the substrate bonded onto the semiconductor wafer is a glass material, but it may be a substrate made of a light-transmitting organic material, ceramic, silicon, or the like.

(A) is sectional drawing of the semiconductor device of the conventional sensor CSP (Chip Scale Package or Chip Size Package) type, (b) is sectional drawing of the camera module using the conventional semiconductor device. It is a flowchart figure which shows the manufacturing method of the semiconductor device which is the 1st Example of this invention. It is sectional drawing in each manufacturing process of the manufacturing method of the semiconductor device which is the 1st Example of this invention. It is a time chart figure of the manufacturing method of the semiconductor device which is the 1st example of the present invention. (A) is sectional drawing of the semiconductor device manufactured by the manufacturing method of the semiconductor device which is the 1st Example of this invention, (b) is sectional drawing of the glass substrate coat | covered with the dielectric film. It is a flowchart figure which shows the manufacturing method of the semiconductor device which is the 2nd Example of this invention. It is sectional drawing in each manufacturing process of the manufacturing method of the semiconductor device which is the 2nd Example of this invention. It is sectional drawing in each manufacturing process of the manufacturing method of the semiconductor device which is the 2nd Example of this invention.

Explanation of symbols

11 Semiconductor wafer 12 Adhesive (first adhesive)
13 Coating glass 20 Sensor CSP
21 Semiconductor element substrate 22 TSV
23 Back wiring 24 Back sealing layer 25 Terminal 26 Semiconductor chip 31 Glass substrate 32 Coating layer 71 Support substrate 72 Auxiliary adhesive (second adhesive)

Claims (8)

A semiconductor wafer preparation step of preparing a semiconductor wafer including a plurality of semiconductor element structures;
A coating substrate preparing step of preparing a coating substrate in which a coating film is formed on a light transmitting substrate having light transmittance;
A bonding step of bonding the coating substrate and the semiconductor wafer, and a manufacturing method of a semiconductor device,
The method of manufacturing a semiconductor device, wherein the bonding step includes a warp correction step of correcting the warpage of the coating substrate by bonding the coating substrate to a correction substrate. The correction substrate is the semiconductor wafer,
The warpage correction step includes an adhesive forming step of applying an adhesive on the semiconductor wafer, a first heating step of heating the adhesive at a semi-curing temperature, and the coating substrate via the adhesive. The semiconductor device according to claim 1, further comprising: an arrangement step of arranging the wafer on the wafer; and a second heating step of heating the adhesive at a curing temperature while pressing the coating substrate against the semiconductor wafer. Manufacturing method.   The warp correction step includes an adhesive forming step of applying an auxiliary adhesive on the correction substrate, and the correction substrate and the coating substrate are temporarily bonded to the correction substrate via the auxiliary adhesive. A warp correction adhesion step of pressing the coating substrate, an arrangement step of arranging the temporarily bonded coating substrate on the semiconductor wafer via an adhesive, and a curing heating step of heating the adhesive at a curing temperature. 2. The method of manufacturing a semiconductor device according to claim 1, further comprising:   The method for manufacturing a semiconductor device according to claim 3, further comprising a peeling step of peeling the correction substrate from the coating substrate after the bonding step.   The method for manufacturing a semiconductor device according to claim 3, wherein the adhesive is applied onto the semiconductor wafer.   5. The method of manufacturing a semiconductor device according to claim 3, wherein the adhesive is applied onto the coating substrate bonded to the correction substrate. 6.   The method of manufacturing a semiconductor device according to claim 4, wherein the auxiliary adhesive is a UV curable adhesive.   The method for manufacturing a semiconductor device according to claim 1, wherein the adhesive is an epoxy resin.

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