JP2008091779A - Manufacturing method of semiconductor device - Google Patents

Abstract

An object of the present invention is to prevent defects (such as chipping or scattering of a semiconductor chip) that occur during a back grinding process and improve the reliability and yield of a semiconductor device.
First, a part of the surface of the semiconductor wafer 1 is removed along each street 2 formed on the surface of the semiconductor wafer 1 to form a groove 4 that reaches the middle in the thickness direction. The groove portion 4 is formed in a region excluding a predetermined interval of the outer peripheral portion 5 of the semiconductor wafer 1. Next, the protective tape 6 is bonded onto the surface of the semiconductor substrate 1 via an adhesive layer. Next, the semiconductor wafer 1 is held on the chuck table 7 so that the front side is opposed. Next, the device element non-formation surface (back surface) of the semiconductor wafer 1 is ground using the back surface grinding apparatus 8 while supplying cutting water. The back grinding process is performed until at least the groove 4 is exposed, whereby the semiconductor wafer 1 is divided into individual semiconductor chips 10.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for dividing a semiconductor wafer into individual semiconductor chips.

  As a method for dividing a semiconductor wafer into individual semiconductor chips, a DBG (Dicing Before Grinding) method is conventionally known. The DBG method is a method in which after cutting to a predetermined depth of a semiconductor wafer to form a groove, an uncut surface is ground (back grinding) to be divided into individual semiconductor chips. This method has advantages such as a reduction in the risk of conveyance cracks between processes and a significant reduction in the thickness of the semiconductor chip compared to a process of dicing after back grinding. The conventional DBG method will be briefly described with reference to the drawings.

  FIG. 4 is a plan view of the semiconductor wafer 100 as viewed from the device element formation surface (hereinafter referred to as the surface) side. The semiconductor wafer 100 in FIG. 5 corresponds to a cross-sectional view taken along the line ZZ in FIG.

  First, various device elements 101 are formed on the surface of the semiconductor wafer 100 using a known semiconductor manufacturing process. Next, the semiconductor wafer 100 is diced to a predetermined depth in the thickness direction along the streets 102 formed on the surface to form the groove portions 103.

  Next, as shown in FIG. 5, a protective tape 104 is attached to the surface side of the semiconductor wafer 100, and then the semiconductor wafer 100 is fixed to the chuck table 105.

  Next, the device element non-formation surface (back surface) of the semiconductor wafer 100 is ground using the back surface grinding device 106 while supplying cutting water. This process is referred to as a back grinding process (back grinding process). This back grinding process is performed until at least the groove 103 is exposed. As a result, the semiconductor wafer 100 is divided into individual semiconductor chips 107 as shown in FIG.

Techniques related to the present invention are described in, for example, the following patent documents.
JP 2001-223186 A

  However, in the conventional method for manufacturing a semiconductor device described above, the outer peripheral portion of the semiconductor wafer 100 particularly fluctuates due to a physical load acting on the semiconductor wafer 100 during the back grinding process, and the protective tape 104 is attached as shown in FIG. In some cases, the semiconductor wafer 100 is warped or distorted. Due to the warpage and distortion, there are problems that the individual semiconductor chips 107 are chipped, the semiconductor chips 107 are scattered outside the chuck table 105, and the semiconductor wafer 100 is detached from the chuck table 105. .

  From the viewpoint of reducing these defects, a special protective tape for firmly fixing the semiconductor wafer 100 to the chuck table 105, a special chuck table, or a special improvement to the back surface grinding apparatus may be added. Though conceivable, there is also a problem that the manufacturing cost increases.

  In view of the above situation, an object of the present invention is to prevent defects that occur during a back grinding process and improve the reliability and yield of a semiconductor device.

  The main features of the present invention are as follows. That is, according to the method for manufacturing a semiconductor device of the present invention, a semiconductor wafer having a surface partitioned into a plurality of regions and having a device element formed in each of the regions is prepared, and a part of the surface of the semiconductor substrate is removed. A step of forming a groove portion that extends along the section of the plurality of regions and reaches the middle of the thickness direction of the semiconductor wafer, a step of bonding a protective member on the surface of the semiconductor wafer on which the groove portion is formed, and at least the above The semiconductor wafer is thinned by grinding the back surface of the semiconductor wafer until the groove is exposed, and the semiconductor wafer is divided into individual semiconductor chips. In the step of forming the groove, the semiconductor The groove is formed in a region excluding the outer periphery of the wafer.

  In the present invention, the groove formed by the DBG method is formed in a region excluding the outer peripheral portion of the semiconductor wafer. As a result, the outer peripheral portion of the semiconductor wafer is held, and defects (such as chipping or scattering of semiconductor chips) during the conventional back grinding process can be prevented.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view of a semiconductor wafer 1 as viewed from the device element formation surface (hereinafter referred to as the surface) side. The surface of the semiconductor wafer 1 is partitioned into a plurality of matrix regions by vertical and horizontal streets 2. In each region, a device element 3 (for example, a light receiving element or a light emitting element) is formed using a known semiconductor manufacturing process.

  First, a part of the surface of the semiconductor wafer 1 is removed along each street 2, and the groove part 4 which reaches the middle of the thickness direction is formed. That is, the groove 4 is formed at a position corresponding to a dicing line that is a boundary between individual semiconductor chips. The depth of the groove 4 corresponds to the finished thickness of the semiconductor chip to be manufactured.

  Here, as shown in FIG. 1 and FIG. 2, the groove 4 is formed in a region excluding a predetermined interval (for example, about 2 mm) of the outer peripheral portion 5 of the semiconductor wafer 1. In other words, the groove portion 4 is formed so that the space of the groove portion 4 is not exposed to the outside when a protective tape 6 described later is attached. The semiconductor wafer 1 in FIG. 2 is a view corresponding to a cross-sectional view along the line XX in FIG.

  Specifically, for example, a resist layer (not shown) is formed on at least the region of the outer peripheral portion 5 on the surface of the semiconductor wafer 1, and dry etching is performed using the resist layer as a mask so that the region other than the outer peripheral portion 5 is removed. A desired groove 4 can be formed. The etching is preferably anisotropic etching from the viewpoint of accuracy, but isotropic etching is also possible.

  Moreover, the groove part 4 can also be formed by removing a part of the semiconductor wafer 1 using a dicing blade or a laser beam. At this time, a contact position and an irradiation position between the dicing blade or the laser beam and the semiconductor wafer 1 are controlled so that the groove 4 is not formed on the outer peripheral portion 5 of the semiconductor wafer 1.

  When a dicing blade is used, the cross-sectional shape of the groove 4 is inevitably a shape corresponding to the shape of the blade. However, according to etching, the cross-sectional shape is changed to a straight shape, a tapered shape, etc. by changing the etching angle. It is possible to Moreover, according to the etching, a planar pattern of the groove 4 can be freely drawn. Therefore, it is possible to arbitrarily finish the shape of the side surface or the plane of the semiconductor chip that is the final product. In addition, the etching can reduce the damage because the cutting surface is less susceptible to mechanical stress than when using a dicing blade or a laser beam, and the groove 4 can be formed smoothly and accurately. There is an advantage that it is possible to prevent chipping. Therefore, from the viewpoint of preventing a mechanical defect and manufacturing a semiconductor device with high reliability and yield, it is preferable to form the groove 4 by etching.

  Next, as shown in FIG. 2, a flexible film-like protective tape 6 is bonded onto the surface of the semiconductor substrate 1 via an unillustrated adhesive layer (for example, epoxy resin, resist, acrylic). The material of the protective tape 6 is not particularly limited as long as it has a function of supporting the semiconductor wafer 1 during the back grinding process and protecting the entire surface of the semiconductor wafer 1. For example, a rigid substrate such as glass, quartz, ceramic, plastic, or metal can be used as the protective member.

  Next, the semiconductor wafer 1 is fixed on the chuck table 7 so as to face the front side. The chuck table 7 is configured so that the semiconductor wafer 1 can be sucked and held.

  Next, the device element non-formation surface (hereinafter referred to as the back surface) of the semiconductor wafer 1 is ground using the back surface grinding apparatus 8 while supplying cutting water. Specifically, while rotating the chuck table 7 at a predetermined rotation speed, the grinding unit 9 of the back surface grinding device 8 is rotated at a predetermined rotation speed, and the grinding unit 9 and the back surface of the semiconductor wafer 1 are brought into contact with each other. Do by. The back grinding process is performed until at least the groove 4 is exposed, whereby the semiconductor wafer 1 is divided into individual semiconductor chips 10 as shown in FIG. Note that the divided semiconductor chip 10 is bonded to the protective tape 6 and thus does not fall apart.

  The target semiconductor chip 10 can be obtained by the above steps.

  In the present embodiment, the groove portion 4 is formed in a region excluding the outer peripheral portion 5 of the semiconductor wafer 1. As a result, the outer peripheral portion 5 of the semiconductor wafer 1 is kept rigid and strongly held. Moreover, since the outer peripheral part 5 is a barrier, cutting water is prevented from entering the groove part 4. For this reason, even if a physical load is generated on the semiconductor wafer 1, the outer peripheral portion of the semiconductor wafer flutters and the semiconductor wafer is not warped or distorted as in the prior art. Further, the distance between the divided semiconductor chips is stable, and there is little contact with each other. Therefore, defects such as chipping of individual semiconductor chips, scattering of the semiconductor chips to the outside of the chuck table, and removal of the semiconductor wafer from the chuck table can be greatly reduced as compared with the prior art.

  Also, unlike the conventional case (see FIG. 6), according to the configuration of the present embodiment, fluttering of the outer peripheral portion of the semiconductor wafer is suppressed, and when the back grinding process is completed, the back surface of each semiconductor chip 10 is substantially horizontal. Is retained. Therefore, it is possible to process the back surface of the semiconductor chip 10 using a well-known semiconductor manufacturing process after the back grinding process. For example, a conductive layer made of aluminum or the like can be formed on the back surface of the semiconductor chip 10 by sputtering, and the conductive layer can be used as a back electrode for substrate bias.

  Moreover, since the outer peripheral part 5 has a role of a barrier, the device elements on the surface of the semiconductor wafer 1 are protected from the intrusion of cutting water and corrosive substances as compared with the prior art.

  Also, with the configuration of this embodiment, a special protective tape (for example, a hard-to-bend protective tape) that firmly fixes the semiconductor wafer is used, a dedicated chuck table is used, and a special improvement is made to the back surface grinding apparatus. Since it is not always necessary to add (for example, a cross-feed polishing function), the manufacturing cost can be suppressed. Cross-feed polishing is a polishing method performed by changing the grinding direction (cutting direction / pattern) in the first stage and the second stage.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be changed without departing from the gist thereof. The present invention can be widely applied to a method of manufacturing a semiconductor device having a back grinding process.

It is a top view which shows the manufacturing method of the semiconductor device which concerns on embodiment of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device which concerns on embodiment of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device which concerns on embodiment of this invention. It is a top view which shows the manufacturing method of the conventional semiconductor device. It is sectional drawing which shows the manufacturing method of the conventional semiconductor device. It is sectional drawing which shows the manufacturing method of the conventional semiconductor device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Street 3 Device element 4 Groove part 5 Outer peripheral part 6 Protection tape 7 Chuck table 8 Back surface grinding apparatus 9 Grinding part 10 Semiconductor chip 100 Semiconductor wafer 101 Device element 102 Street 103 Groove part 104 Protection tape 105 Chuck table 106 Back surface grinding apparatus 107 Semiconductor chip

Claims (3)

Preparing a semiconductor wafer whose surface is partitioned into a plurality of regions and device elements are formed in each of the regions;
Removing a part of the surface of the semiconductor substrate, and forming a groove portion that reaches the middle of the thickness direction of the semiconductor wafer along with the sections of the plurality of regions;
Bonding a protective member on the surface of the semiconductor wafer on which the groove is formed;
The semiconductor wafer is thinned by grinding the back surface of the semiconductor wafer until at least the groove is exposed, and the semiconductor wafer is divided into individual semiconductor chips, and
In the step of forming the groove portion, the groove portion is formed in a region excluding the outer peripheral portion of the semiconductor wafer. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a part of the surface of the semiconductor wafer is etched in the step of forming the groove. After the step of dividing the semiconductor wafer into individual semiconductor chips,
The method for manufacturing a semiconductor device according to claim 1, further comprising a step of forming a conductive layer on a back surface of the semiconductor chip.

Images