JP2009123809A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To favorably form a protection film to a side surface of a thin semiconductor chip by a grinding process. <P>SOLUTION: A plurality of channels (4) are formed in the shape of a lattice to one principal plane (1a) of a semiconductor wafer (1), a thermally-vaporizing substance (5) vaporized by heat treatment is supplied to a part of the channel (4), and thereafter a protection resin (6) is supplied to fill the channel (4) on the thermally vaporizing substance (5). Next, after the thermally vaporizing substance (5) is vaporized by heating the semiconductor wafer (1) to form a cavity (7) in the lower channel (4) of the protection resin (6), the other principal plane (1b) of the semiconductor wafer (1) is ground by a grinder (10) until the grinding surface reaches the cavity (7). Thereafter, the protection resin (6) is cut along the center of the protection resin (6) to divide the wafer into a plurality of semiconductor chips (3) covered with the protection resin (6) at the side surface (3c). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a protective film can be favorably formed on a side surface of a semiconductor chip that is thinned by grinding.

  For example, in the conventional method of manufacturing a semiconductor device in which a protective film is formed on the side surface of a thin semiconductor chip, a main surface (1a) of a semiconductor wafer (1) is formed along a partition line (D) as shown in FIG. After the plurality of grooves (4) are formed in a lattice shape by a dicer or the like, the protective resin (6) is filled into the plurality of grooves (4) by a dispensing method or a screen printing method as shown in FIG. For example, a groove (4) having a bottom (4a) width of about 150 μm and a side wall (4c) depth of about 200 μm is formed on a semiconductor wafer (1) having a thickness of about 400 μm. As the protective resin (6), for example, a siloxane resin such as a silicone resin or a thermosetting resin such as a polyimide resin is used. Next, the semiconductor wafer (1) in the state shown in FIG. 9 is carried into a clean oven or the like, the protective resin (6) in the plurality of grooves (4) is heated and cured, and then the semiconductor wafer (1) is inverted. Then, as shown in FIG. 10, a holding tape (2) as a holding body is attached to one main surface (1a) of the semiconductor wafer (1) including the groove (4). Then, as shown in FIG. 10, the semiconductor wafer (until the grinding surface (G) at which the protective resin (6) is exposed is reached by a grinding device (10) such as a grinding wheel connected to the drive device (11). The other main surface (1b) of 1) is ground uniformly. Finally, by cutting along the center of the protective resin (6), a plurality of thin semiconductor chips (3) whose side surfaces (3c) are covered with the protective resin (6) with the protective resin (6) can be obtained. A method for manufacturing a semiconductor device whose side surfaces are covered with a protective resin is disclosed, for example, in Patent Document 1 below.

JP 2006-32598 A

  In the manufacturing method of the semiconductor device described in Patent Document 1, a groove is formed in a divided region partitioned into a plurality of chip regions on the main surface of the semiconductor wafer, and the semiconductor wafer is filled with a silicon oxide film in the groove. Wafer reinforcement adhesive tape and cover adhesive tape are attached to the surface to reinforce the semiconductor wafer, and in that state, the back surface opposite to the main surface of the semiconductor wafer is ground to reduce the thickness of the semiconductor wafer, and then into the groove Various heat treatments are performed in a state where the silicon oxide film is embedded. According to Patent Document 1, a thin semiconductor chip can be satisfactorily manufactured without causing cracks, defects or warpage in a wafer-like semiconductor wafer.

By the way, in the above-described conventional method for manufacturing a semiconductor device, as a physical property required for the protective resin (6) to be filled in the groove (4) of the semiconductor wafer (1), the protective resin is used after grinding by the grinding device (10). To avoid problems such as warping of the semiconductor wafer (1) or cracking of the protective resin (6) due to stress from (6), for example, Shore A hardness is small and flexible. It is necessary to use a high resin. However, filling the groove (4) of the semiconductor wafer (1) with a highly flexible protective resin (6) and grinding the semiconductor wafer (1) and the protective resin (6) at the same time with the grinding device (10), When the grinding device (10) comes into contact with the protective resin (6), a large tensile stress is generated on the protective resin (6), so that the protective resin (6) is damaged after grinding or is severe. As shown in FIG. 11, there is a problem that the protective resin (6) is scraped from the groove (4) and the side surface (3c) of the semiconductor chip (3) is exposed. For example, when the Shore A hardness after curing is 15 or less and the protective resin (6) has a tensile strength of about 5.0 × 10 ⁵ Pa or less, the grinding device (10) rotates while rotating 0.3 to 0.3. When the semiconductor wafer (1) and the protective resin (6) are ground simultaneously by moving horizontally at a speed of about 5 μm / s, almost all of the protective resin (6) is scraped out of the groove (4). Therefore, in the conventional manufacturing method in which the semiconductor wafer (1) is thinned by grinding and divided into regions of a plurality of semiconductor chips (3), a protective resin (on the side surface (3c) of each semiconductor chip (3) to be thinned ( It was difficult to satisfactorily form a protective film by sufficiently attaching 6).

  Therefore, an object of the present invention is to provide a method for manufacturing a semiconductor device, in which a protective film can be favorably formed on the side surface of a semiconductor chip that is thinned by grinding.

  The method of manufacturing a semiconductor device according to the present invention includes a step of forming a plurality of grooves (4) in a lattice shape on one main surface (1a) of a semiconductor wafer (1), and a thermally vaporizable substance (5) that is vaporized by heating. By supplying a part of the groove (4), filling the groove (4) with a protective resin (6) from above the thermally vaporizable substance (5), and heating the semiconductor wafer (1) Vaporizing the thermally vaporizable substance (5) to form a cavity (7) in the groove (4) below the protective resin (6); and until the cavity (7) is reached, the semiconductor wafer (1) A step of grinding the other main surface (1b), and a plurality of semiconductors in which the protective resin (6) is cut along the center of the protective resin (6) and the side surfaces (3c) are respectively covered with the protective resin (6) Dividing the chip (3).

  After supplying the thermally vaporizable substance (5) into the groove (4) formed on one main surface (1a) of the semiconductor wafer (1), the heat vaporizable substance (5) is placed into the groove (4) from above. Fill with protective resin (6). After that, when the semiconductor wafer (1) is heated, the thermally vaporizable substance (5) at the bottom (4a) of the groove (4) is vaporized to form the cavity (7) or the cavity (7) is formed. At the same time, the protective resin (6) is cured. In this state, until the grinding surface reaches the cavity (7) adjacent to the protective resin (6) in the groove (4), if the other main surface (1b) of the semiconductor wafer (1) is uniformly ground, The protective resin (6) can be held in the groove (4) without being damaged or scraped off by the grinding device (10). Thereafter, if the protective resin (6) is cut along the center, a plurality of semiconductor chips (3) whose side surfaces (3c) are covered with the protective resin (6) can be obtained.

  In the present invention, when a semiconductor wafer is thinned by grinding and divided into a plurality of semiconductor chips by dicing or the like, a protective resin having a sufficient thickness is attached to the side surface of each thin semiconductor chip and the protective resin is ground during grinding. Thus, a highly reliable semiconductor device with a high manufacturing yield can be manufactured.

  Hereinafter, an embodiment of a method of manufacturing a semiconductor device according to the present invention will be described with reference to FIGS. However, in FIGS. 1-8, the same code | symbol is attached | subjected to the part substantially the same as the location shown in FIGS. 9-11, and the description is abbreviate | omitted.

  In the method of manufacturing the semiconductor device of the present embodiment, first, as shown in FIG. 2, a high impurity concentration N + type semiconductor region as the first semiconductor region of the first conductivity type is formed by impurity diffusion, epitaxial growth, or the like. A low impurity concentration N− type semiconductor region as a third conductivity type third semiconductor region and a high impurity concentration P + type semiconductor as a second conductivity type second semiconductor region different from the first conductivity type A disk-shaped semiconductor wafer (1) shown in FIG. 1 composed of a silicon single crystal substrate formed by sequentially stacking regions is prepared. As is well known, the semiconductor wafer (1) of FIG. 1 is later divided into a large number of semiconductor chips (3) by dicing. In the present embodiment, the semiconductor chip (3) is shown as a general PN junction type diode structure, but the present invention is not limited to the diode, and other various semiconductors such as a transistor, a thyristor, a triac (TRIAC), etc. It can be applied to the manufacture of devices.

  Subsequently, as shown in FIG. 2, the semiconductor wafer (1) is cut from one main surface (1a) of the semiconductor wafer (1) by a dicer or the like along the grid-like partition lines (D) shown in FIG. Then, lattice-like grooves (4) are formed in the semiconductor wafer (1). In the present embodiment, the width of the bottom portion (4a) is about 150 μm to 200 μm and the depth of the side wall portion (4c) with respect to the semiconductor wafer (1) having a thickness of about 400 μm, for example, by dicing with a dicer and wet etching. Forms a groove (4) of about 200 μm. Thus, since the lattice-like groove (4) is formed on one main surface (1a) of the semiconductor wafer (1), the semiconductor wafer (1) has a plurality of semiconductor chips (3 ).

  Next, as shown in FIG. 3, the heat vaporizable substance (5) is applied to the bottom (4a) of the groove (4) using a dispenser or screen printing. As the heat vaporizable substance (5) which is vaporized by heating, polyethylene glycol (PEG) which is liquid at normal temperature having a boiling point of 197 ° C. is used. When the liquid heat-evaporable substance (5) is applied to the bottom (4a) of the groove (4), it protrudes above the heat-evaporable substance (5) due to the surface tension acting on the upper surface of the heat-evaporable substance (5). A part (5a) is formed.

  Subsequently, as shown in FIG. 4, a liquid protective resin (6) is filled into the groove (4) from above the thermally vaporizable substance (5) using a dispenser or screen printing. As the protective resin (6), a thermosetting silicone resin or a polyimide resin is used. For example, a curing temperature is about 150 ° C., and a silicone resin having a heat resistance of 300 ° C. or more is preferable. When the liquid protective resin (6) is filled into the groove (4) from above the thermally vaporizable substance (5), it is below the protective resin (6) in contact with the convex part (5a) of the thermally vaporizable substance (5). The recess (6a) shown in FIG. 5 is formed.

  After that, as shown in FIG. 5, the semiconductor wafer (1) is carried into a heating device such as a clean oven (not shown) and heated at a temperature of about 150 ° C. for 1 hour to protect the protective resin (6 in the groove (4)). ) Is cured. After curing of the protective resin (6), when the temperature is further raised to around 200 ° C. to completely vaporize the thermally vaporizable substance (5), the protective resin (6) enters the groove (4) below the recess (6a). A cavity (7) is formed.

  After forming the cavity (7) in the groove (4), as shown in FIG. 6, the semiconductor wafer (1) is inverted, and one main surface (1a) of the semiconductor wafer (1) including the groove (4) is formed. ) Is attached with a holding tape (2) as a holding body having elasticity. As the holding tape (2), a tape material or a film material made of a resin having elasticity is used, and an adhesive surface facing the one main surface (1a) of the semiconductor wafer (1) including the groove (4) is adhered. The agent is applied.

  Next, as shown in FIG. 6, the grinding device (10) connected to the driving device (11) is moved on the other main surface (1b) of the semiconductor wafer (1) in the horizontal direction while rotating. Rotate the other main surface (1b) of the semiconductor wafer (1) until it reaches the grinding surface (G) that contacts the peripheral edge (6b) of the recess (6a) of the protective resin (6) filled in the groove (4). Grind uniformly. Thereby, as shown in FIG. 7, the N + type semiconductor region on the other main surface (1b) side of the semiconductor wafer (1) is ground and thinned, and the protective resin (6) in the groove (4) is obtained. Is divided into a plurality of adjacent semiconductor chips (3).

  After that, when the protective resin (6) shown in FIG. 7 is cut along the center line (C) and the holding tape (2) is pulled and expanded in the horizontal direction, a large gap is formed between the plurality of semiconductor chips (3). It is formed. In this state, if the divided semiconductor chips (3) are adsorbed by a collet or the like and removed from the holding tape (2), a plurality of thin semiconductor chips whose side surfaces (3c) are covered with the protective resin (6) (3) is obtained.

  In the present embodiment, after supplying the thermally vaporizable substance (5) vaporized by heating into the groove (4) formed on one main surface (1a) of the semiconductor wafer (1), the thermally vaporizable substance (5 The thermosetting protective resin (6) is filled into the groove (4) from above. Thereafter, the semiconductor wafer (1) is heated at about 150 ° C. for 1 hour to cure the protective resin (6) in the groove (4), and further heated to about 200 ° C., the bottom (4a) of the groove (4) All of the thermally vaporizable substance (5) is vaporized to form the cavity (7). In this state, the other main surface (1b) of the semiconductor wafer (1) is uniformly ground until it reaches the grinding surface (G) that contacts the peripheral edge (6b) of the recess (6a) of the protective resin (6). The protective resin (6) can be held in the groove (4) without damaging or scraping the protective resin (6) by the grinding device (10). Thereafter, the protective resin (6) is cut along the center line (C) to divide the semiconductor wafer (1) into a plurality of semiconductor chips (3), and the divided semiconductor chips (3) are held on the holding tape (2 ), A plurality of thin semiconductor chips (3) whose side surfaces (3c) are covered with the protective resin (6) can be obtained. Therefore, when the semiconductor wafer (1) is thinned by grinding and divided into a plurality of semiconductor chips (3) by dicing, a thickness sufficient or necessary for the side surface (3c) of each thin semiconductor chip (3) A protective film (6) can be adhered to form a protective film. Further, when the other main surface (1b) of the semiconductor wafer (1) is ground by the grinding device (10) and divided into regions of a plurality of semiconductor chips (3), each semiconductor chip is placed on the holding tape (2). Since (3) is securely held by the adhesive force, it does not scatter when each semiconductor chip (3) contacts the grinding device (10). Furthermore, when the holding tape (2) having elasticity is expanded by pulling in the horizontal direction, a large gap is formed between the semiconductor chips (3). Can be easily adsorbed, removed from the holding tape (2), and easily moved.

  Embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made. For example, in the above embodiment, since the boiling point (197 ° C.) of the heat vaporizable substance (5) is higher than the curing temperature (about 150 ° C.) of the protective resin (6), the protective resin (6) is cured. Later, the thermally vaporizable substance (5) was vaporized to form the cavity (7) .On the contrary, the thermally vaporizable substance (5) having a boiling point lower than the curing temperature of the protective resin (6) was obtained. In use, the protective resin (6) may be cured after vaporizing the thermally vaporizable substance (5) to form the cavity (7). In this case, after attaching the heat-resistant holding tape (2) to one main surface (1a) of the semiconductor wafer (1) including the groove (4) and directing the other main surface (1b) upward The semiconductor wafer (1) may be heated. Further, as shown in FIG. 8, a pore (8) communicating with the other main surface (1b) of the semiconductor wafer (1) is formed in the bottom (4a) of the groove (4), and the groove (4) When supplying the heat-vaporizable substance (5), the heat-vaporizable substance (5) is held in the groove (4) by the viscosity of the heat-vaporizable substance (5) itself, and vaporized by heating the semiconductor wafer (1). The vapor of the thermally vaporizable substance (5) to be released may be released from the pores (8) provided at the bottom (4a) of the groove (4). Further, in the above embodiment, the semiconductor wafer (1) until the grinding surface (G) in contact with the peripheral edge (6b) of the recess (6a) of the protective resin (6) filled in the groove (4) is reached. The other main surface (1b) is uniformly ground by the grinding device (10), but when the grinding device (10) reaches the cavity (7) adjacent to the protective resin (6) in the groove (4). The grinding of the other main surface (1b) of the semiconductor wafer (1) may be stopped. In the above embodiment, a silicone resin is used as the protective resin (6), but a polyimide resin may be used. Furthermore, the present invention is not limited to the manufacture of a PN junction type diode chip, and the present invention can be applied to the manufacture of various transistors or thyristors, monolithic integrated circuits, and the like.

  The present invention can be suitably applied to the manufacture of a semiconductor device having a resin protective film that covers the side surface of a semiconductor chip that is thinned by grinding.

The perspective view which shows the state which forms a some groove | channel on one main surface of a disk-shaped semiconductor wafer in a grid | lattice form. Sectional drawing which shows the state which forms several groove | channels in one main surface of a semiconductor wafer Sectional drawing which shows the state which apply | coats a heat vaporizable substance to the bottom part of several groove | channels Sectional drawing which shows the state which fills a protective resin in a groove | channel from the upper direction of a thermally vaporizable substance Sectional drawing which shows the state which heated the semiconductor wafer and vaporized the heat vaporizable substance in a groove | channel Sectional drawing which shows the state which grinds the other main surface of a semiconductor wafer with a grinding device until it reaches the peripheral part of the recessed part of protective resin Sectional drawing which shows the state divided | segmented into several semiconductor chips on both sides of protective resin by grinding Sectional drawing which shows the state which apply | coats a heat vaporizable substance to the bottom part of the some groove | channel provided with the pore Sectional drawing which shows the state filled with protective resin in the some groove | channel formed in one main surface of a semiconductor wafer Sectional drawing which shows the state which grinds the other main surface of a semiconductor wafer with a grinding device until it reaches protection resin Sectional drawing which shows the state in which protective resin was scraped from the plurality of grooves after grinding

Explanation of symbols

  (1) ・ ・ Semiconductor wafer, (1a) ・ ・ One main surface, (1b) ・ ・ Other main surface, (2) ・ ・ Holding tape (holder), (3) ・ ・ Semiconductor chip, (3a ) ・ ・ One main surface, (3b) ・ ・ Other main surface, (3c) ・ ・ Side, (4) ・ ・ Groove, (4a) ・ ・ Bottom, (4b) ・ ・ Bottom, (4c) ・・ Sidewall part (5) ・ ・ Heat-vaporizing substance, (5a) ・ ・ Convex part (6) ・ ・ Protective resin, (6a) ・ ・ Concave part (6b) ・ ・ Rim, (7) ・ ・Cavity, (8) ・ ・ Pore, (10) ・ ・ Grinding device, (11) ・ ・ Drive device, (D) ・ ・ Division line, (G) ・ ・ Grinding surface, (C) ・ ・ Center line ,

Claims (6)

Forming a plurality of grooves in a lattice shape on one main surface of the semiconductor wafer;
Supplying a thermally vaporizable substance that is vaporized by heating to a part of the groove;
Filling the groove with a protective resin from above the thermally vaporizable substance;
Heating the semiconductor wafer to vaporize the thermally vaporizable substance to form a cavity in the groove below the protective resin; and
Grinding the other main surface of the semiconductor wafer until reaching the cavity,
Cutting the protective resin along the center of the protective resin, and dividing the protective resin into a plurality of semiconductor chips each having a side surface covered with the protective resin.   The method for manufacturing a semiconductor device according to claim 1, further comprising a step of attaching an elastic holding body to one main surface of the semiconductor wafer including the groove before grinding the other main surface of the semiconductor wafer. .   3. The method of manufacturing a semiconductor device according to claim 1, wherein the protective resin is a thermosetting silicone resin or a polyimide resin, and the heat-vaporizable substance is polyethylene glycol.   The manufacturing method of the semiconductor device of Claim 3 including the process of hardening the said protective resin, after vaporizing the said heat vaporizable substance which has a boiling point lower than the hardening temperature of the said protective resin. Forming a pore communicating with the bottom surface of the semiconductor wafer at the bottom of the groove;
Holding the thermo-vaporizable substance in the groove by the viscosity of the thermo-vaporizable substance itself when supplying the thermo-vaporizable substance in the groove;
The manufacturing method of the semiconductor device of any one of Claims 1-4 including the process of discharge | releasing the vapor | steam of the said heat vaporizable substance to vaporize from the said pore.   Before forming a plurality of grooves on one main surface of the semiconductor wafer, a first semiconductor region having a first conductivity type and a second conductivity type different from the first conductivity type The manufacturing method of the semiconductor device of any one of Claims 1-5 including the process of forming the semiconductor area | region of this in the said semiconductor wafer.

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