JP2011029439A - Method for manufacturing chip with metal layer - Google Patents

Abstract

When dividing a workpiece such as a semiconductor wafer having a metal layer formed on the back surface to obtain a large number of chips, high-quality chips are efficiently obtained.
A groove having a depth equal to the thickness of a solder layer 5 is formed at a position corresponding to the planned dividing line 2 of the solder layer (metal layer) 5 on the back surface 1b side before cutting the planned dividing line 2 of the wafer 1. 6 is formed, and then the wafer 1 is cut along the division line 2 to divide the wafer 1 into a large number of chips 4 with solder layers. At the time of division, only the wafer 1 is cut, and since the solder layer 5 is not cut, no burrs are generated from the solder layer 5.
[Selection] Figure 4

Description

  The present invention relates to a method for manufacturing a chip such as a semiconductor chip, and more particularly to a method for manufacturing a chip with a metal layer in which a metal layer such as a solder layer is formed on the back surface.

  For example, when a semiconductor wafer having a large number of devices formed on its surface is divided into devices to obtain individual semiconductor chips, a cutting dicing apparatus is widely used. The cutting-type dicing apparatus uses a cutting blade in which a superabrasive such as diamond or CBN (Cubic Boron Nitride) is fixed to the outer peripheral edge of a disk-shaped substrate made of metal or resin to form a blade, for example, 30000 rpm ( It is cut into a semiconductor wafer while rotating at a high speed of about revolutions per minute), and the cutting allowance of the semiconductor wafer is cut and removed (see Patent Document 1, etc.).

  A semiconductor chip divided from a semiconductor wafer is mounted on a printed circuit board, and soldering is widely adopted as a technique for mounting. For soldering, it is necessary to form a solder layer on the back surface of the semiconductor chip. Therefore, at the stage of the semiconductor wafer, the solder layer is formed on the back surface of the semiconductor wafer.

JP-A-8-25209

  By the way, when a semiconductor wafer is divided into a large number of semiconductor chips, the semiconductor wafer is usually supported on the inner side of a ring-shaped frame via an adhesive tape in order to facilitate transport of an extremely thin semiconductor wafer. The adhesive tape is provided with an adhesive layer on one side, and the back side and the frame of the semiconductor wafer are adhered to the adhesive layer, and the semiconductor wafer is conveyed by handling the frame.

  A semiconductor wafer having a metal layer such as a solder layer formed on the back side as described above has an adhesive tape attached to the metal layer side. When the semiconductor wafer is cut from the front side with a cutting blade in this state, In some cases, burrs generated in the layer bite into the adhesive tape. When the burrs of the metal layer bite into the adhesive tape in this way, there arises a problem that it becomes difficult to pick up individual semiconductor chips after division. On the other hand, when cutting from the metal layer side is considered, since the metal layer becomes an obstacle and it is impossible to image the planned division line on the surface side, cutting from the metal layer side is impossible.

  The present invention has been made in view of the above circumstances, and its object is to divide a workpiece such as a semiconductor wafer having a metal layer formed on the back surface to obtain a large number of chips. An object of the present invention is to provide a chip manufacturing method that can be obtained efficiently.

  The present invention is a method for manufacturing a chip with a metal layer having a metal layer, and a protective member attaching step of attaching a protective member to the surface of a work whose surface is partitioned into a plurality of chip regions by a division line. And a workpiece grinding step of thinning the workpiece by grinding the back surface opposite to the surface of the workpiece after the protective member attaching step, and an outer peripheral edge at least on the back surface of the workpiece after the grinding step A metal layer forming step of forming a metal layer on the back surface except for at least a part of, and after the metal layer forming step, by imaging an area where the metal layer on the back surface of the workpiece is not formed with an infrared camera, Based on the planned dividing line detection step for detecting the position of the planned dividing line formed on the surface of the workpiece, and the position of the planned dividing line detected in the planned dividing line detection step, A groove forming step of forming a groove having a depth equal to the thickness of the metal layer at a position corresponding to the division line on the metal layer side; and after the groove forming step, on the surface of the metal layer on the back side of the workpiece Adhesive tape adhering step for adhering the adhesive tape, a protective member peeling step for removing the protective member from the surface of the workpiece after the adhesive tape adhering step, and a line for dividing the workpiece after the protective member peeling step And a dividing step of dividing the workpiece into a plurality of chips.

  According to the above method, in the groove forming process, a groove is formed at a position corresponding to the planned division line of the metal layer and the metal layer at the position is removed in advance. It becomes possible to cut. For this reason, the problem that the burr | flash which generate | occur | produced in the metal layer, for example at the time of cut | disconnecting and cutting | disconnecting a workpiece | work cuts into an adhesive tape can be prevented.

  In addition, although the workpiece said by this invention is not specifically limited, For example, semiconductor wafers, such as a silicon wafer, the package of a semiconductor product, a ceramic, glass type, or a silicon-type board | substrate, Furthermore, the precision of a micron order is requested | required. Various processing materials are mentioned.

  According to the present invention, when a workpiece such as a semiconductor wafer having a metal layer formed on the back surface is cut and divided into a large number of chips, a high-quality chip can be efficiently obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the wafer divided | segmented into many semiconductor chips in one Embodiment of this invention, Comprising: (a) Wafer single-piece | unit, (b) The wafer by which the protective tape was affixed on the surface at the protective tape affixing process, (C) A wafer having a solder layer formed on the back surface in the solder layer forming step. It is a perspective view of the wafer by which the adhesive tape with a frame was stuck on the solder layer side in the adhesive tape sticking process of one embodiment. It is sectional drawing which shows the process of one Embodiment, Comprising: (a) Masking tape sticking process, (b) Wafer grinding process, (c) Solder layer formation process, (d) The division | segmentation scheduled line detection process is shown. It is sectional drawing which shows the process of one Embodiment, Comprising: (a) Groove formation process, (b) Adhesive tape sticking process, (c) Protection tape peeling process, (d) Dividing process are shown. It is sectional drawing which shows the division | segmentation process by the conventional method which does not form a groove | channel in a solder layer. (A) It is sectional drawing which shows the division | segmentation process by the conventional laser processing, (b) It is sectional drawing which shows the division | segmentation process of other embodiment of this invention by laser processing.

  Hereinafter, an embodiment in which the present invention is applied to a manufacturing method for obtaining a large number of semiconductor chips from a semiconductor wafer will be described with reference to the drawings.

(1) Wafer In this embodiment, a disk-shaped semiconductor wafer (hereinafter referred to as wafer) 1 shown in FIG. 1A is used as a workpiece, and a solder layer is formed on the back surface of the wafer 1. In this method, the wafer 1 with the solder layer is divided to obtain a large number of semiconductor chips (hereinafter referred to as chips) having solder layers on the back surface. The wafer 1 is a silicon wafer having a thickness of, for example, about 700 μm, and a large number of rectangular devices (chip regions) 3 partitioned by lattice-shaped division lines 2 are formed on the surface 1a. On the surface of each device 3, an electronic circuit such as an IC or LSI (not shown) is formed.
Hereafter, the process of this embodiment is demonstrated.

(2) Manufacturing Method Step (2-1) Protective Tape Affixing Step First, as shown in FIG. 1B and FIG. 3A, the entire surface 1a of the wafer 1 is protected to protect the electronic circuit. A protective tape (protective member) 10 is adhered to the substrate. As the protective tape 10, for example, a resin base sheet made of polyolefin having a thickness of about 70 to 200 [mu] m is formed on one side with an adhesive layer of about 5 to 20 [mu] m, and the adhesive layer is matched to the surface 1a of the wafer 1. Affixed.

(2-2) Wafer Grinding Step Next, as shown in FIG. 3B, the back surface 1b of the wafer 1 is ground using the grinding means 20, and the wafer 1 has a predetermined thickness (for example, about 50 to 100 μm). To thin. The grinding means 20 has a grinding wheel 22 fixed to the tip of a spindle 21 that rotates at a high speed. The grinding wheel 22 has a grinding wheel 24 fixed to the lower surface of a disk-like frame 23 fixed to the tip of the spindle 21. The grinding wheel 24 that rotates at a high speed together with the spindle 21 applies a load to the surface 1 a of the wafer 1. While pressing, the surface 1a of the wafer 1 is ground. The wafer 1 is sucked and held by a holding means such as a vacuum chucking chuck table via a protective tape 10 on the front surface 1a side, and the holding means rotates and rotates, whereby the entire exposed back surface 1b is ground on the grinding wheel 24. It is ground with. In order to grind the back surface 1b of the wafer 1 in this way, for example, a grinding apparatus described in JP-A-2002-319559 is suitably used.

(2-3) Solder Layer Forming Step Next, as shown in FIGS. 1C and 3C, a circular solder layer (metal layer) 5 leaving the outer peripheral edge on the back surface 1b of the wafer 1. Form. The solder layer 5 has a thickness of about several μm to several tens of μm, for example, and can be formed by a thin film forming means for forming a solder alloy material into a thin film by vapor deposition or sputtering. The solder layer 5 covers all of the rectangular devices 3 on the front surface 1 a of the wafer 1, and an irregular chip that is not used as a product is formed on the outer peripheral edge of the exposed back surface 1 b that is a non-formation region of the solder layer 5. Only exist.

(2-4) Scheduled Line Detection Step Next, as shown in FIG. 3 (d), a part of the outer peripheral edge of the back surface 1b of the wafer 1 where the solder layer 5 is not formed is imaged by the infrared camera 30. Based on the captured image, the positions of all the planned division lines 2 formed on the surface are detected.

(2-5) Groove Formation Step Subsequently, as shown in FIG. 4A, all the planned division lines on the solder layer 5 side are based on the positions of the planned division lines 2 detected in the division planned line detection step. A groove 6 having a depth equivalent to the thickness of the solder layer 5 is formed at a position corresponding to 2. The groove 6 can be formed by cutting a cutting blade 40 of a cutting-type dicing apparatus that cuts the planned dividing line 2 of the wafer 1 into the solder layer 5 and processing and feeding it along the detected planned dividing line 2. it can. Since the groove 6 has the same depth as the solder layer 5, the back surface 1 b of the wafer 1 is exposed at the portion where the groove 6 is formed.

  The dividing line detection step and the groove formation step are performed continuously while the wafer 1 is held on the chuck table of the cutting apparatus described in, for example, the above-mentioned allowed document 1 (Japanese Patent Laid-Open No. 8-25209). Is called.

(2-6) Adhesive Tape Adhesion Step Next, as shown in FIG. 2 and FIG. 4 (b), the surface of the solder layer 5 (solder layer 5) in which the groove 6 is formed at a position corresponding to the division line 2 The adhesive tape 12 stretched on the ring-shaped frame 11 is attached to the exposed surface of the film. The adhesive tape 12 has an adhesive surface on one side. A frame 11 is attached to the adhesive surface, and the wafer 1 is positioned concentrically inside the frame 11 and attached to the adhesive surface. The frame 11 has rigidity made of a plate material such as metal, and the wafer 1 is transported by handling the frame 11. In FIG. 4B, the wafer 1 is inverted from the state of FIG. 4A so that the surface 1a side of the wafer 1 faces up.

(2-7) Protective tape peeling process Next, as shown in FIG.4 (c), the protective tape 10 stuck to the surface 1a of the wafer 1 is peeled, and the surface 1a is exposed.

(2-8) Dividing Step After the protective tape 10 is peeled off, the surface 1a of the wafer 1 is imaged by an imaging means (not shown), and all of the planned dividing lines 2 formed on the surface 1a are formed based on the captured image. Detect position. Subsequently, as shown in FIG. 4D, the cutting blade 41 is processed and fed along the planned division line 2, and all the planned division lines 2 are cut. As the cutting blade 41, the one provided in the cutting device used in the groove forming step can be used. The cutting depth of the cutting blade 41 with respect to the wafer 1 only needs to penetrate the thickness of the wafer 1 and cut the wafer 1.

  As described above, the wafer 1 is divided into a large number of chips (chips with solder layers) 4 in which the device 3 is formed on the front surface and the solder layer 5 is formed on the back surface. The divided chips 4 are attached to the adhesive tape 12, and are picked up from the adhesive tape 12 in a later pickup process. The picked-up chip 4 is mounted on a printed circuit board or the like by using the solder layer 5 by soldering.

(3) Effects According to the chip manufacturing method of the present embodiment, the groove 6 is formed at a position corresponding to the planned dividing line 2 of the solder layer 5 in the groove forming step, and the solder layer 5 at the position is removed in advance. Therefore, only the wafer 1 without the solder layer 5 on the back surface 1b side can be cut by the cutting blade 41 during the dividing step. When the wafer 1 is divided from the surface 1a side without forming the groove 6, the cutting blade 41 penetrates the wafer 1 and the solder layer 5 as shown in FIG. It happens that 5a bites into the adhesive tape 12.

  When the burr 5a bites into the adhesive tape 12, it becomes difficult to peel off the chip 4 from the adhesive tape 12, and the chip 4 cannot be picked up smoothly in the pickup process. However, in this embodiment, since the cutting blade 41 cuts only the wafer 1 and does not cut the solder layer 5, the divided chip 4 is healthy without burrs. For this reason, the chip 4 can be picked up smoothly.

  Although it is possible to suppress the generation of burrs from the solder layer 5 by slowing the machining feed rate of the cutting blade without forming the grooves 6, fast processing is performed after the grooves 6 are formed as in this embodiment. Dividing the wafer 1 at the feeding speed can shorten the total processing time. As a result, productivity can be improved in combination with smooth pickup as described above.

(4) Other Embodiments In the above embodiment, the wafer 1 is cut and divided along the planned dividing line 2 in the dividing step by cutting using a cutting blade. Alternatively, an ablation process may be used in which the components of the wafer 1 are evaporated and removed by irradiating the laser beam along the division line 2.

  As shown in FIG. 6A, when the ablation processing is performed by irradiating the division line 2 with the laser beam L from the surface 1a side of the wafer 1 without forming the groove 6 in the solder layer 5, the wafer 1 and the solder layer 5 is cut, but at this time, the debris 5b which is a transpiration component of the solder layer 5 may adhere to the side surface of the chip 4 to contaminate the chip 4 and reduce the quality.

  However, in the present invention, since the above groove forming step is included, in the dividing step, the laser beam L is irradiated only on the wafer 1 and the wafer 1 is cut as shown in FIG. Does not occur. For this reason, the chip 4 is not contaminated by the debris of the solder layer 5 and is kept in a healthy state.

1 ... wafer (work)
DESCRIPTION OF SYMBOLS 1a ... Front surface 1b ... Back surface 2 ... Planned division line 3 ... Device (chip area | region)
4 ... Chip with solder layer 5 ... Solder layer (metal layer)
6 ... groove 10 ... protective tape (protective member)
12 ... Adhesive tape 30 ... Infrared camera

Claims (1)

A method of manufacturing a chip with a metal layer having a metal layer,
A protective member adhering step for adhering a protective member to the surface of the workpiece whose surface is partitioned into a plurality of chip regions by a division line
After the protective member attaching step, a workpiece grinding step of thinning the workpiece by subjecting the back surface, which is the surface opposite to the surface of the workpiece, to grinding.
After the grinding step, a metal layer forming step of forming a metal layer on the back surface except at least a part of the outer peripheral edge on the back surface of the workpiece;
After the metal layer forming step, the position of the division line formed on the front surface of the workpiece is detected by imaging a portion of the back surface of the workpiece where the metal layer is not formed with an infrared camera. Dividing line detection process to be performed;
Groove formation for forming a groove having a depth equal to the thickness of the metal layer at a position corresponding to the planned division line on the metal layer side based on the position of the planned division line detected in the planned division line detection step Process,
After the groove forming step, an adhesive tape adhering step of adhering an adhesive tape to the surface of the metal layer that is the back side of the workpiece;
A protective member peeling step for peeling off the protective member from the surface of the workpiece after the adhesive tape attaching step;
A method for producing a chip with a metal layer, comprising a step of cutting the workpiece along the planned dividing line and dividing the workpiece into a plurality of chips after the protective member peeling step.

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