Wafer processing method

Abstract

To provide a processing method of a wafer in which a traceability for each device chip is secured while allowing takeover of past information for each device chip.SOLUTION: A processing method of a wafer comprises: a cutting device preparation step; an information registration step of registering information to be marked in control means of a cutting device; a holding step of exposing a back surface 38b side of a wafer 38 by holding a front surface side of the wafer 38 having a front surface in which a plurality of devices 42 are segmented by a division schedule line 40, on a chuck table 4 of the cutting device; a location registration step of imaging the wafer 38 held on the chuck table 4 with imaging means 8 of the cutting device, specifying a position of each device 42 which has to be marked in an X-coordinate and a Y-coordinate, and registering it in the control means; and a marking step of marking the information registered in the information registration step on the back surface of an individual device 42 with a cutting blade 22 on the basis of the X-coordinate and Y-coordinate registered in the location registration step.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer. [Background technology]

[0002] A wafer having a plurality of devices such as ICs and LSIs formed on its front surface and partitioned along planned dividing lines has its back surface ground by a grinding device to form it to the desired thickness, and is then divided into individual device chips by a cutting device. Each of the divided device chips is used in electrical equipment such as mobile phones and personal computers.

[0003] A barcode, product number, product name, and letters or an ID mark including a lot number are marked on the wafer at a desired position (for example, in the peripheral surplus area adjacent to the orientation flat) for managing the wafer. The ID mark is checked at each manufacturing process to perform the desired processing on the wafer, while also transferring past information and ensuring traceability (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-330196 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a wafer is divided into individual device chips, there arises a problem that past information cannot be transferred for each device chip, and traceability cannot be ensured.

[0006] In view of the above, an object of the present invention is to provide a wafer processing method that enables the transfer of past information for each device chip and ensures traceability for each device chip. [Means for solving the problem]

[0007] According to the present invention, there is provided the following wafer processing method that solves the above problems: That is, the wafer processing method includes a cutting device preparation step of preparing a cutting device including at least a rotatable chuck table that holds a wafer, cutting means having a rotatable cutting blade that cuts the wafer held on the chuck table, X-axis feed means that relatively feeds the chuck table and the cutting means in an X-axis direction, Y-axis feed means that relatively indexes and feeds the chuck table and the cutting means in a Y-axis direction perpendicular to the X-axis direction, Z-axis feed means that relatively cuts and feeds the chuck table and the cutting means in a Z-axis direction perpendicular to the X-axis and Y-axis directions, imaging means that images the wafer held on the chuck table, display means that displays an image captured by the imaging means, and control means; The present invention provides a wafer processing method including: an information registration step of registering information to be marked in the control means; a holding step of holding the front side of a wafer, the front side of which has a surface divided by planned dividing lines, on the chuck table and exposing the back side of the wafer; a position registration step of imaging the wafer held on the chuck table with the imaging means, specifying the positions of each device to be marked in X and Y coordinates and registering them in the control means; and a marking step of operating the X-axis feed means and the Y-axis feed means based on the X-axis and Y-coordinates registered in the position registration step to position the cutting blade at a desired position and operating the Z-axis feed means, thereby marking the information registered in the information registration step on the back side of each device with the cutting blade.

[0008] Preferably, the marking step is carried out before dividing the wafer into individual device chips. It is desirable to carry out a surface protection member providing step of providing a protection member on the surface of the wafer before the holding step.

[0009] It is preferable that the method includes a wafer supporting step of adhering a dicing tape to the back surface of the wafer and supporting the wafer via the dicing tape with a frame having an opening for accommodating the wafer, and a dividing step of peeling off the protective member from the front surface of the wafer and dividing the wafer into individual device chips.

[0010] It is convenient to carry out the marking step after dividing the wafer into individual device chips. It is preferable to include a retaining member providing step, prior to the holding step, of providing a retaining member for maintaining the shape of the wafer on the surface of the wafer divided into individual device chips. Effect of the Invention

[0011] The wafer processing method of the present invention includes a cutting device preparation step of preparing a cutting device including at least a rotatable chuck table for holding a wafer, cutting means having a rotatable cutting blade for cutting the wafer held on the chuck table, X-axis feed means for relatively feeding the chuck table and the cutting means in an X-axis direction, Y-axis feed means for relatively indexing and feeding the chuck table and the cutting means in a Y-axis direction perpendicular to the X-axis direction, Z-axis feed means for relatively cutting the chuck table and the cutting means in a Z-axis direction perpendicular to the X-axis and Y-axis directions, imaging means for imaging the wafer held on the chuck table, display means for displaying an image captured by the imaging means, and control means, and a step of registering information to be marked in the control means. The method includes an information registration step, a holding step of holding the front side of a wafer, the front side of which has a surface divided by planned dividing lines, on the chuck table and exposing the back side of the wafer, a position registration step of imaging the wafer held on the chuck table with the imaging means, specifying the positions of each device to be marked in X and Y coordinates and registering them in the control means, and a marking step of operating the X-axis feed means and the Y-axis feed means based on the X-axis and Y coordinates registered in the position registration step to position the cutting blade at a desired position and operating the Z-axis feed means, and marking the information registered in the information registration step on the back side of each device with the cutting blade. Therefore, past information can be passed on for each device chip and traceability for each device chip is ensured. [Brief description of the drawings]

[0012] [Figure 1] FIG. [Diagram 2] FIG. 13 is a perspective view showing a state in which a surface protection member disposing step is being carried out. [Diagram 3] FIG. 2A is a perspective view showing a state in which a wafer is positioned above a chuck table, and FIG. 2B is a perspective view showing a state in which the wafer is held by the chuck table. [Figure 4] FIG. 13 is a perspective view showing a state in which a position registration process is being performed. [Diagram 5]FIG. 2A is a perspective view showing a state in which a marking process is being performed, and FIG. 2B is a partial plan view of the back surface side of the wafer on which marking has been performed. [Figure 6] FIG. 13 is a perspective view showing a state in which a wafer supporting step is being performed. [Figure 7] FIG. [Figure 8] FIG. 2 is a perspective view of a wafer divided into device chips. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the wafer processing method of the present invention will be described with reference to the drawings.

[0014] (Cutting device preparation process) In the illustrated embodiment, a cutting device preparation step is first performed to prepare a required cutting device. For example, the cutting device prepared in this step may be the cutting device 2 shown in FIG.

[0015] The cutting device 2 includes at least a rotatable chuck table 4 for holding a wafer, a cutting means 6 having a rotatable cutting blade for cutting the wafer held on the chuck table 4, an X-axis feed means (not shown) for relatively feeding the chuck table 4 and the cutting means 6 in the X-axis direction, a Y-axis feed means (not shown) for relatively indexing and feeding the chuck table 4 and the cutting means 6 in the Y-axis direction perpendicular to the X-axis direction, a Z-axis feed means (not shown) for relatively cutting and feeding the chuck table 4 and the cutting means 6 in the Z-axis direction perpendicular to the X-axis direction and the Y-axis direction, an imaging means 8 for imaging the wafer held on the chuck table 4, a display means 10 for displaying an image captured by the imaging means 8, and a control means 12. The X, Y, and Z-axis directions are respectively indicated by arrows X, Y, and Z in FIG. 1. The XY plane defined by the X-axis and Y-axis directions is substantially horizontal, and the Z-axis direction is the up-down direction.

[0016] The chuck table 4 is configured to be movable in the X-axis direction and rotatable about the Z-axis direction. A porous circular suction chuck 14 connected to suction means (not shown) is disposed on the upper end portion of the chuck table 4. The suction means generates a suction force on the upper surface of the suction chuck 14, thereby suction-holding the wafer placed on the upper surface of the suction chuck 14. In addition, a plurality of clamps 16 are disposed on the periphery of the chuck table 4 at intervals in the circumferential direction.

[0017] Explaining with reference to Figures 1 and 5, the cutting means 6 includes a spindle housing 18 (see Figure 5) configured to be freely movable in both the Y-axis and Z-axis directions, a spindle 20 rotatably supported by the spindle housing 18, an annular cutting blade 22 fixed to the tip of the spindle 20, and a motor (not shown) that rotates the spindle 20.

[0018] The X-axis feed means has a ball screw connected to the chuck table 4 and extending in the X-axis direction, and a motor that rotates the ball screw. The X-axis feed means converts the rotational motion of the motor into linear motion using the ball screw and transmits it to the chuck table 4, and feeds the chuck table 4 in the X-axis direction relative to the cutting means 6 for processing.

[0019] The Y-axis feed means includes a ball screw connected to the spindle housing 18 of the cutting means 6 and extending in the Y-axis direction, and a motor that rotates the ball screw. The Y-axis feed means converts the rotational motion of the motor into linear motion by the ball screw and transmits it to the spindle housing 18, thereby indexing and feeding the cutting means 6 in the Y-axis direction relative to the chuck table 4.

[0020] The Z-axis feed means includes a ball screw connected to the spindle housing 18 and extending in the Z-axis direction, and a motor for rotating the ball screw. In the Z-axis feed means, the ball screw converts the rotational motion of the motor into linear motion and transmits it to the spindle housing 18, so that the cutting means 6 is fed to cut into the chuck table 4 in the Z-axis direction.

[0021] The imaging means 8 is disposed above the orbit of the chuck table 4. The imaging means 8 includes a normal image sensor (CCD) that images the wafer with visible light, an infrared irradiation means that irradiates the wafer with infrared rays, an optical system that captures the infrared rays irradiated by the infrared irradiation means, and an image sensor (infrared CCD) that outputs an electrical signal corresponding to the infrared rays captured by the optical system (none of which are shown). The image captured by the imaging means 8 is sent to the display means 10 and the control means 12.

[0022] The control means 12 is composed of a computer having a central processing unit (CPU) that performs arithmetic processing according to a control program, a read-only memory (ROM) that stores the control program and the like, and a readable and writable random access memory (RAM) that stores the arithmetic results and the like.

[0023] The cutting device 2 further includes a vertically movable cassette table 26 on which a cassette 24 containing a plurality of wafers is placed, a loading / unloading means 30 that pulls out the wafer before processing from the cassette 24 and transports it to the temporary placement table 28, and at the same time, loads the processed wafer positioned on the temporary placement table 28 into the cassette 24, a first transport means 32 that transports the wafer before processing carried out from the cassette 24 to the chuck table 4, a cleaning means 34 that cleans the processed wafer, and a second transport means 36 that transports the processed wafer from the chuck table 4 to the cleaning means 34.

[0024] (Information registration step) After performing the cutting device preparation step, an information registration step of registering the information to be marked in the control means 12 is performed. The information to be marked is information for identifying each of the plurality of devices formed on the wafer.

[0025] (Surface protection member arrangement step) In the illustrated embodiment, after performing the information registration step, a surface protection member arrangement step of arranging a protection member on the surface of the wafer is performed.

[0026] 2 shows a wafer 38 that can be processed by the wafer processing method of this embodiment. The wafer 38 is disk-shaped and can be made of an appropriate semiconductor material such as silicon. A surface 38a of the wafer 38 is partitioned into a plurality of rectangular regions by lattice-shaped division lines 40, and a device 42 such as an IC or an LSI is formed in each of the rectangular regions. In addition, a notch 44 indicating a crystal orientation is formed on the periphery of the wafer 38.

[0027] 2, in the surface protective member disposing step, a circular protective member 46 having approximately the same diameter as the diameter of the wafer 38 is disposed on the surface 38a of the wafer 38. The protective member 46 may have an adhesive layer, and in this case, this step can be carried out by attaching the protective member 46 to the surface 38a of the wafer 38. Note that when a thermocompression sheet such as polyolefin is used as the protective member 46, the adhesive layer is not necessary.

[0028] (holding process) After the surface protection member arrangement process is performed, a holding process is performed in which the front surface 38a side of a wafer 38 having a surface 38a partitioned by planned division lines 40 into which a plurality of devices 42 are formed is held on a chuck table 4, and the back surface 38b side of the wafer 38 is exposed.

[0029] 3, in the holding step, first, the wafer 38 is placed on the upper surface of the chuck table 4 with the surface 38a of the wafer 38 facing downward. Next, the suction means connected to the suction chuck 14 is operated to generate a suction force on the upper surface of the suction chuck 14, and the wafer 38 is suction-held on the upper surface of the suction chuck 14.

[0030] (Location registration process) After the holding step is performed, a position registration step is performed in which the wafer 38 held on the chuck table 4 is imaged by the imaging means 8, and the position of each device 42 to be marked is identified by X and Y coordinates and registered in the control means 12.

[0031] In the position registration step, first, the chuck table 4 is moved by the X-axis feed means, and the wafer 38 is positioned below the imaging means 8. Next, the wafer 38 held on the chuck table 4 is imaged by the imaging means 8. Next, based on the image of the wafer 38 imaged by the imaging means 8, the planned dividing line 40 is aligned in the X-axis direction.

[0032] At this time, the back surface 38b of the wafer 38 faces upward, and the front surface 38a on which the planned division lines 40 are formed faces downward. However, as described above, the imaging means 8 includes an infrared irradiation means, an optical system for capturing infrared light, and an imaging element (infrared CCD) for outputting an electrical signal corresponding to the infrared light, so that the planned division lines 40 on the front surface 38a can be imaged through the back surface 38b of the wafer 38.

[0033] Next, the position of each device 42 to be marked is specified by X and Y coordinates. In this case, for example, as shown in FIG. 4, the position of the device 42 can be specified by detecting the X and Y coordinates of each intersection of the center lines L of the planned division lines 40. Specifically, the coordinates of the four intersections (X, Y) around the device 42a are 3 , Y 3 ), (X 3 , Y 4 ), (X 4 , Y 3 ), (X 4 , Y 4 ) can identify the location of the device 42a to be marked. In this manner, the locations of all the devices 42 are identified by X and Y coordinates.

[0034] In the position registration step, the position of the device 42 may be specified by detecting the X and Y coordinates of a characteristic pattern (key pattern) on the device 42, instead of the intersection coordinates around the device 42. The origin of the X and Y coordinates can be set arbitrarily. For example, the origin of the X and Y coordinates can be set to the notch 44.

[0035] (Marking process) After the position registration process is performed, the X-axis feed means and the Y-axis feed means are operated based on the X-coordinates and Y-coordinates registered in the position registration process to position the cutting blade 22 at the desired position, and the Z-axis feed means is operated to perform a marking process in which the information registered in the information registration process is marked on the back surface of each device 42 with the cutting blade 22.

[0036] In the marking step, first, the chuck table 4 is moved by the X-axis feed means, and the wafer 38 is positioned below the cutting means 6. Next, based on the X and Y coordinates registered in the position registration step, the X-axis feed means and the Y-axis feed means are operated, and the cutting blade 22 is positioned above the device 42 to be marked.

[0037] Next, the spindle housing 18 is lowered by the Z-axis feed means, and the cutting edge of the cutting blade 22, which is rotating at high speed, is caused to cut from the back surface 38b of the wafer 38 to an extent that does not reach the front surface 38a, while cutting water is supplied to the portion where the cutting edge of the cutting blade 22 is to cut. Then, as shown in Fig. 5, the X-, Y-, and Z-axis feed means are operated appropriately to repeatedly cause the cutting edge of the cutting blade 22 to cut into the back surface 38b of the wafer 38, thereby forming a marking 48, which may be in the form of a barcode, on the back surface of the device 42.

[0038] After the marking 48 has been formed on one device 42, the marking 48 is repeated while the chuck table 4 is moved in the X-axis direction by the distance in the X-axis direction of the planned division lines 40. After the markings 48 have been formed on all of the devices 42 in one row, the chuck table 4 is moved in the Y-axis direction by the distance in the Y-axis direction of the planned division lines 40, and markings 48 are formed on the devices 42 in the next row. In this manner, the markings 48 are formed on all of the devices 42 on the wafer 38.

[0039] (Wafer support process) In the illustrated embodiment, after the marking step is performed, a dicing tape 50 is attached to the back surface 38b of the wafer 38, and a wafer supporting step is performed in which the wafer 38 is supported via the dicing tape 50 by a frame 52 having an opening 52a for accommodating the wafer 38, as shown in Fig. 6. The wafer supporting step is performed after the suction force of the chuck table 4 is released and the wafer 38 is removed from the chuck table 4.

[0040] (splitting process) After the wafer supporting step is performed, a dividing step is performed in which the protective member 46 is peeled off from the front surface 38a of the wafer 38 and the wafer 38 is divided into individual device chips.

[0041] In the dividing step, first, as shown in Fig. 6, the protective member 46 is peeled off from the front surface 38a of the wafer 38. Next, the wafer 38 is suction-held on the upper surface of the chuck table 4 with the front surface 38a of the wafer 38 facing upward. In addition, the frame 52 is fixed by the clamps 16 of the chuck table 4. Next, the wafer 38 is imaged by the imaging means 8, and based on the image of the wafer 38 imaged by the imaging means 8, the planned dividing lines 40 are aligned in the X-axis direction, and the area corresponding to the planned dividing lines 40 aligned in the X-axis direction is positioned below the cutting blade 22.

[0042] Next, as shown in FIG. 7, the cutting edge of the cutting blade 22, which is rotated at high speed, is caused to cut from the front surface 38a to the back surface 38b, and cutting water is supplied to the portion where the cutting edge of the cutting blade 22 is to be cut, while the chuck table 4 (omitted in FIG. 7) is processed and fed in the X-axis direction relative to the cutting means 6, thereby forming a division groove 54 along the intended division line 40.

[0043] Then, the cutting blade 22 is indexed and fed in the Y-axis direction relative to the chuck table 4 by an amount equal to the spacing of the division lines 40 in the Y-axis direction, while repeatedly forming the division grooves 54, to form the division grooves 54 along all of the division lines 40 aligned in the X-axis direction. The chuck table 4 is then rotated 90 degrees, and the cutting blade 22 is indexed and fed, while repeatedly forming the division grooves 54, to form the division grooves 54 along all of the division lines 40 that are perpendicular to the division lines 40 along which the division grooves 54 were previously formed. In this manner, the wafer 38 is divided into individual device chips, as shown in FIG. 8.

[0044] As described above, in the illustrated embodiment, the markings 48 are formed for each device 42 by cutting, so that past information can be passed on for each device chip, and traceability for each device chip is ensured.

[0045] In the illustrated embodiment, an example has been described in which the marking step is performed before dividing the wafer 38 into individual device chips, but the marking step may also be performed after dividing the wafer 38 into individual device chips.

[0046] When the marking step is performed after division, it is preferable to carry out a wafer supporting step and a dividing step, and then a maintaining member providing step in which a maintaining member (which may be, for example, a circular adhesive tape similar to protective member 46) for maintaining the shape of wafer 38 is provided on front surface 38a of wafer 38 divided into individual device chips, and then peel wafer 38 from dicing tape 50, and then carry out a holding step, a position registration step, and a marking step. [Explanation of symbols]

[0047] 2:Cutting device 4: Chuck table 6:Cutting means 8: Imaging means 10:Display means 12: Control means 22: Cutting blade 38: Wafer 38a: Surface of wafer 38b: Back side of wafer 40: Planned division line 42: Device 46: Protective material 48: Marking 50: Dicing tape 52: Frame 52a: Frame opening

Claims

1. A method for processing a wafer, comprising the steps of: a cutting device preparation step of preparing a cutting device including at least a rotatable chuck table for holding a wafer, cutting means having a rotatable cutting blade for cutting the wafer held on the chuck table, X-axis feed means for relatively feeding the chuck table and the cutting means in an X-axis direction, Y-axis feed means for relatively indexing and feeding the chuck table and the cutting means in a Y-axis direction perpendicular to the X-axis direction, Z-axis feed means for relatively cutting the chuck table and the cutting means in a Z-axis direction perpendicular to the X-axis and Y-axis directions, imaging means for imaging the wafer held on the chuck table, display means for displaying an image captured by the imaging means, and control means; an information registration step of registering information to be marked in the control means; a holding step of holding a front side of a wafer having a surface divided by dividing lines into a plurality of devices on the chuck table and exposing a back side of the wafer; a position registration step of imaging the wafer held on the chuck table with the imaging means, specifying the position of each device to be marked in terms of X and Y coordinates, and registering the specified position in the control means; a marking step of operating the X-axis feed means and the Y-axis feed means to position the cutting blade at a desired position based on the X- and Y-coordinates registered in the position registration step and operating the Z-axis feed means to mark the information registered in the information registration step on the back surface of each device with the cutting blade; A method for processing a wafer comprising the steps of:

2. 2. The method of claim 1, wherein said marking step is carried out before dividing the wafer into individual device chips.

3. 2. The method for treating a wafer according to claim 1, further comprising the step of providing a surface protective member on the surface of the wafer prior to said holding step.

4. 4. The method for processing a wafer according to claim 3, comprising: a wafer supporting step of adhering a dicing tape to a back surface of the wafer and supporting the wafer via the dicing tape with a frame having an opening for accommodating the wafer; and a dividing step of peeling off the protective member from the front surface of the wafer to divide the wafer into individual device chips.

5. 2. The method for treating a wafer according to claim 1, wherein the marking step is carried out after dividing the wafer into individual device chips.

6. 6. The method for processing a wafer according to claim 5, further comprising a step of providing a supporting member for maintaining the shape of the wafer on the surface of the wafer divided into individual device chips, prior to said holding step.

Images