JP6037705B2 - Workpiece processing method - Google Patents

Description

  The present invention relates to a workpiece processing method for processing a workpiece using two cutting devices (dicing devices).

  Semiconductor wafers in which a plurality of electronic circuits such as IC and LSI are formed on a silicon substrate and various ceramic substrates, resin substrates, glass substrates, etc. used for electronic components are individually processed by a cutting device (dicing device). Divided into chips, the divided chips are widely used in various electric devices.

  In the cutting device, cutting is performed by cutting a cutting blade including superabrasive grains mounted on the tip of a spindle into a workpiece such as a wafer while rotating at high speed. In recent years, in a semiconductor device manufacturing process that requires high accuracy and high quality, a method called step cut that cuts a line to be cut using two different cutting blades has been widely adopted.

  In step cutting, a cutting groove having a predetermined depth is formed with a first cutting blade, and then the wafer is divided into individual chips by cutting the center of the bottom of the cutting groove with a second cutting blade. In step cutting, a wafer with a predetermined thickness is cut twice, so that the amount of cutting when cutting with each cutting blade is compared to the method of cutting with one cutting blade at a time (single cut) It is possible to reduce the processing load at the time of cutting and to perform cutting with good processing quality.

  In this step cut, it is important that the second cutting blade does not cut the position outside the cutting groove formed by the first cutting blade. Use a cutting blade with a thick blade.

  On the other hand, in the cutting machine, cutting is performed by positioning the reference line of the camera of the machine at the center of the planned cutting line of the wafer called street. And the distance (index value) from one street to the next.

  The cutting device detects the registered target pattern, detects the planned cutting line based on the distance from the registered target pattern, and automatically performs cutting by index feeding the cutting blade with the registered index value. Do.

  In the cutting process, an operation (hairline alignment) of aligning the reference line of the camera mounted on the cutting apparatus with the center line of the cutting blade in advance is performed. Specifically, this hairline alignment work is performed by once processing a groove on the surface of the wafer with a cutting blade, imaging the processed groove, performing image processing, detecting the center of the processed groove, By calculating the amount of deviation from the camera reference line position and adding or subtracting this deviation amount to the coordinate position, the correction position that matches the center position of the machining groove and the camera reference line position is stored in the device. Is going.

  When step cutting is performed with two cutting devices, the two cutting blades are mounted on different spindles, respectively, but thermal expansion occurs in each spindle with high-speed rotation. Even when the cutting blade and the reference line are aligned at the start of cutting, the position of the cutting blade is displaced due to thermal expansion accompanying the processing. In view of this, a kerf check is performed in which the cutting groove cut during the cutting process is imaged with a camera to confirm the cutting groove, and the cutting blade and the reference line of the camera are aligned.

JP 2011-233641 A JP 58-84280 A Japanese Patent Laid-Open No. 2008-4806

  When step cutting is performed using two cutting devices, the bottom of the first cutting groove cut by the first cutting device is cut with the cutting blade of the second cutting device, and the second cutting groove is cut. When the kerf check of the second cutting groove is performed, the second cutting groove cannot be accurately detected by the previously formed first cutting groove, and there is a problem that the kerf check is difficult.

  The present invention has been made in view of the above points, and an object of the present invention is to cut the groove bottom of the first cutting groove when a workpiece is cut using two cutting devices. Then, it is providing the processing method of the workpiece which enables the kerf check of the 2nd cutting groove at the time of forming the 2nd cutting groove.

According to the present invention, there is provided a processing method for a workpiece that is performed by using the first cutting device and the second cutting device, and the first holding device holds the workpiece by the first holding means of the first cutting device. A holding step and a first cutting step of forming a plurality of first cutting grooves having a first width by cutting the workpiece held by the first holding means by the first cutting means of the first cutting device. And at a predetermined timing during the execution of the first cutting step, the first cutting groove is imaged by the first imaging means having the first reference line of the first cutting device, and the first reference line and A first cutting groove checking step for measuring the positional relationship and checking the first cutting groove formed in the first cutting step, and a second holding means of the second cutting device after performing the first cutting step A second holding step for holding the workpiece in step, and after performing the second holding step, the second holding step A second cutting step of cutting a bottom of each first cutting groove with a second cutting means of a cutting device to form a second cutting groove having the same width as the first cutting groove or a width narrower than the first cutting groove; Before performing at least the second cutting step, a plurality of second cutting groove confirmation cutting lines are set in a peripheral excess region where the first cutting groove is not formed on the workpiece. setting a step, in each of a plurality of predetermined timings during implementation of the second cutting step, any of the plurality of second cutting grooves confirmation cutting lines which are set by the second cutting grooves confirmation cutting line setting step or the formation of the second cut grooves confirmation groove is cut, the second imaging means in the second cutting grooves confirmation groove by capturing said second reference having a second reference line of the second cutting device Measuring the positional relationship with the line, and forming the second cutting formed in the second cutting step. Seen containing a second cutting grooves confirmation step of confirming the grooves, and the workpiece, a second direction perpendicular to the plurality of first preset cutting line extending in the first direction, the direction of the first And a plurality of second cutting scheduled lines extending in the first cutting line are set in parallel to the first cutting planned line, and the second cutting step includes the second cutting cutting lines for confirming the cutting grooves. In the second cutting groove confirmation step after forming the second cutting groove in the two cutting scheduled lines, the second holding groove confirmation groove is formed after the second holding means is rotated 90 degrees. A method for processing a workpiece is provided.

  Preferably, in the second cutting groove confirmation step, the second cutting groove confirmation groove is imaged to detect the width of the second cutting groove confirmation groove and / or the size of chipping generated in the groove.

  According to the present invention, when step cutting is performed using two cutting devices, the groove bottom of the first cutting groove formed by the first cutting device is cut by the second cutting device to form the second cutting groove. The kerf check of the second cutting groove when formed can be performed accurately without being affected by the first cutting groove.

It is an external appearance perspective view of the 1st cutting device and 2nd cutting device which were installed in the process chamber. It is a flowchart which shows the outline of the processing method of this invention. It is a top view of a wafer explaining a cutting line for kerf check. 4A is a plan view showing the first and second cutting grooves formed by the processing method of the present invention, and FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a first cutting device 2 </ b> A and a second cutting device 2 </ b> B are installed in a processing chamber 30. Reference numeral 32 denotes a door for an operator (operator) to enter and exit the processing chamber 30. Since the first and second cutting devices 2A and 2B have the same configuration, the following description will be made in detail on the first cutting device 2A as a representative.

  On the front side of the first cutting apparatus 2A, an operation means 4 is provided for an operator to input instructions to the apparatus such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 3, on the surface of the wafer W to be diced, the first street (scheduled cutting line) S1 and the second street (scheduled cutting line) S2 are formed orthogonal to each other. A large number of devices D are formed on the wafer W by being partitioned by the second street S1 and the second street S2. The wafer W has a device region 11 in which a large number of devices D are formed, and an outer peripheral surplus region 13 surrounding the device region 11 on its surface.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is The first chuck is sucked by the transport means 16 and transported onto the first chuck table (holding table) 18 and is sucked by the first chuck table 18, and the frame F is fixed by a plurality of fixing means 19. It is held on the table 18.

  The first chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction, and detects a street of the wafer W to be cut above the movement path of the first chuck table 18 in the X-axis direction. An alignment means 20 is provided.

  The alignment unit 20 includes a first imaging unit 22 having a microscope and a camera for imaging the surface of the wafer W, and based on the image acquired by the first imaging unit, a street to be cut by image processing such as pattern matching. Can be detected. The image acquired by the first imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment unit 20, a first cutting unit 24 that performs a cutting process on the wafer W held on the first chuck table 18 is disposed. The 1st cutting means 24 is comprised integrally with the alignment means 20, and both move in the Y-axis direction and a Z-axis direction interlockingly.

  The first cutting means 24 is configured by attaching a first cutting blade 28 to the tip of a rotatable spindle 26 and is movable in the Y-axis direction and the Z-axis direction. The first cutting blade 28 is located on the extension line of the first imaging means 22 in the X-axis direction. The wafer W that has been subjected to the cutting process is transported to the spinner cleaning means 27 by the transport means 25, and spin cleaned and spin dried by the spinner cleaning means 27.

  The second cutting device 2B has substantially the same configuration as the first cutting device 2A. Describing schematically, the second cutting apparatus 2B includes a second chuck table (holding table) 18B configured to be rotatable and reciprocally movable in the X-axis direction, and a microscope and a camera for imaging the surface of the wafer W. The second imaging unit 22B and the second cutting unit 24B are provided.

  The second cutting means 24B is configured by mounting a second cutting blade 28B, preferably different from the first cutting blade 28, on the tip of a rotatable spindle. In the present embodiment, the width of the second cutting blade 28B is narrower than that of the first cutting blade 28, but both may be the same width.

  In the workpiece processing method according to the embodiment of the present invention, as shown in step S10 in the flowchart of FIG. 2, first, the wafer W as the workpiece is held by the first chuck table 18 of the first cutting apparatus 2A. The first holding step is performed.

  Then, the first chuck table 18 holding the wafer W is positioned directly below the first imaging means 22 to image the wafer W, and the first street S1 and the second street S2 are separated from the first cutting blade 28 and the X. Perform alignment to align in the axial direction. Since this alignment step is a well-known step, detailed description thereof is omitted here.

  After the alignment step, a first cutting step is performed in which the wafer W held by the first chuck table 18 is cut by the first cutting means 24 to form a first cutting groove 28 (see FIG. 4) having a first width. Implement (step S11).

  In the first cutting step, the first cutting blade 28 is rotated at a high speed while the first street (first cutting scheduled line) S1 to be cut is aligned with the first cutting blade 28. The first cutting means 24 is lowered by a predetermined amount, the first cutting blade 28 is cut into the wafer W, and the first chuck table 18 is processed and fed in the X-axis direction, so that as shown in FIG. A relatively shallow first cutting groove 30 is formed.

  While indexing and feeding the first cutting means 24 in the Y-axis direction, the first cutting grooves 30 are sequentially formed in all the first streets S1. In FIG. 4B, reference numeral 34 denotes a low dielectric constant insulating film (Low-k film).

  The first cutting groove 30 formed by the first image pickup means 22 is picked up at a predetermined timing while cutting the first street S1, and the first reference line and the first cutting groove 30 of the camera of the first image pickup means 22 are picked up. The first cutting groove confirmation step for confirming whether or not the first cutting groove 30 is formed at the correct position, that is, the kerf check of the first cutting groove 30 is performed.

  In the kerf check of the first cutting groove 30, it is detected whether or not the center of the first cutting groove 30 matches the first reference line. 1 The cutting means 24 is moved in the Y-axis direction and corrected so as to match (hairline alignment). In addition, in the kerf check of the first cutting groove 30, not only hairline alignment is performed, but also the width and chipping size of the first cutting groove 30 are detected.

  When the cutting of all the first streets S1 is completed, the first chuck table 18 is rotated by 90 degrees, and then the second streets S2 extending in the second direction are cut along the second streets S2. A similar first cutting groove 30 is formed. A kerf check of the first cutting groove 30 formed along the second street S2 is performed at a predetermined timing during the cutting of the second street S2.

  After performing the first cutting step, the wafer W is removed from the first chuck table 18, and a second holding step is performed in which the wafer W is held by the second chuck table 18B of the second cutting apparatus 2B (step S12).

  Next, the wafer W is moved directly below the second image pickup means 22B of the second cutting device 2B, and the second image pickup means 22B images the first cutting groove 30 formed by the first cutting blade 28, and the second cutting is performed. An alignment is performed in which the second cutting blade 28B of the means 24B is positioned at the center of the first cutting groove 30. This alignment is performed for the first cutting groove 30 extending in the first direction and the second direction.

  Next, the process proceeds to step S13 in FIG. 2 to set a kerf check cutting line. That is, as shown in FIG. 3, for the kerf check for checking the kerf during the cutting of the first scheduled cutting line (first street) S1 in the outer peripheral surplus area 13 where the first cutting groove 30 of the wafer W is not formed. A plurality of kerf check cutting lines 17 for performing a kerf check during the cutting of the cutting line 15 and the second scheduled cutting line (second street) S2 are set.

  The kerf check cutting lines 15 and 17 are parallel to the first street S1 extending in the first direction, and the distance between them is arbitrary. The y coordinate values of the kerf check cutting lines 15 and 17 are stored in the memory of the second cutting device 2B.

  After setting the cutting line for alignment and kerf check as described above, the second cutting means 24B is rotated by a predetermined amount while the second cutting blade 28B is rotated at a high speed in a state where the second cutting blade 28B is aligned with the center of the first cutting groove 30. When the second cutting blade 28B is cut down to the dicing tape T and the second chuck table 18B is processed and fed in the X-axis direction, the second cutting blade 30B is centered on the first cutting groove 30 as shown in FIG. A groove 32 is formed.

  While indexing and feeding the second cutting means 24B in the Y-axis direction, the second cutting step of sequentially forming the second cutting grooves 32 in the bottom of the first cutting grooves 30 formed in the first street S1 is performed ( Step S14).

  During execution of the second cutting step along the first street S1, the kerf check cutting line 15 is cut by the second cutting blade 28B at a predetermined timing to cut a kerf check cutting groove (second cutting groove checking groove). The kerf check cutting groove is imaged by the second imaging means 22B, and a kerf check is performed to determine whether the center of the kerf check cutting groove matches the reference line of the camera of the second imaging means 22B. carry out.

  If they do not match, correction is performed by moving the second cutting means 24B in the Y-axis direction by the amount of deviation, and this correction value is stored in the memory, and the subsequent second cutting step is corrected with this correction value. It implements based on the y-coordinate value.

  The kerf check cutting groove formed by cutting the kerf check cutting line 15 performed at a predetermined timing during the cutting of the first street S1 is a substitute for the second cutting groove 32. By checking the kerf, it can be used as a kerf check of the second cutting groove 32.

  In the kerf check step (second cutting groove confirmation step) of the second cutting groove, the second cutting groove confirmation groove is imaged to detect the width of the second cutting groove confirmation groove, and for the second cutting groove confirmation. The size of chipping generated in the groove is detected.

  Then, it is determined whether or not the width of the groove and the size of the generated chipping are within a predetermined allowable range. When the width exceeds the predetermined allowable range, the cutting of the wafer W is stopped and the problem is confirmed. This problem includes an imaging error and a defect of the second cutting blade 28B. If it is determined that the second cutting blade 28B is defective, the second cutting blade 28B is replaced with a new one.

  The cutting of the kerf check cutting line 15 performed during the cutting of the first street S1 by the second cutting blade 28B in step S14 is performed every time a predetermined number of the first streets S1 are cut.

  When the cutting of the first street S1 is completed, the second chuck table 18B is rotated 90 degrees, and then the bottom of the first cutting groove 30 formed in the second street S2 is cut by the second cutting means 24B. A second cutting step for forming the second cutting groove 32 is performed (step S15).

  The second cutting blade 28B cuts the second street S2 at a predetermined timing to cut the kerf check cutting line 17 shown in FIG. 3 to form a second cutting groove check groove (kerf check cutting groove). Then, the second cutting groove confirmation groove is imaged and a kerf check of the second cutting groove confirmation groove is performed.

  At this time, in order to cut the kerf check cutting line 17, the second chuck table 18B is rotated 90 degrees, and then the kerf check cutting line 17 is cut to form a second cutting groove checking groove.

  The second cutting groove confirmation step (kerf check step) performed at a predetermined timing during the cutting of the second street S2 is a second cutting groove confirmation step performed at a predetermined timing during the cutting of the first street S1. Similarly to the (kerf check step), the second groove confirmation groove is imaged to detect the width of the second groove confirmation groove and the size of chipping generated in the groove. Of course, hairline alignment is also performed in which the center of the second cutting groove confirmation groove is aligned with the camera reference line of the second imaging means 22B.

  The cutting of the kerf check cutting line 17 performed at a predetermined timing during the cutting of the second street S2 is performed every time a predetermined number of the second streets S2 are cut. The kerf check performed in the second cutting groove confirmation groove is a substitute for the kerf check of the second cutting groove 32 formed in the second street S2.

  According to the processing method of the above-described embodiment, the second cutting groove check groove is formed by cutting the kerf checking cutting lines 15 and 17 in which the kerf check of the second cutting groove 32 is set in the outer peripheral surplus area 17 of the wafer W. Since the kerf check is performed with the second cutting groove confirmation groove, the second cutting groove 32 formed by the second cutting apparatus 2B can be detected by the first cutting groove 30 formed by the first cutting apparatus 2A. Therefore, the problem that the kerf check of the second cutting groove 32 is difficult is solved.

  The wafer processing method of the embodiment described above is suitable for the wafer W in which the width of the outer peripheral surplus region 13 at both ends of the first cutting line S1 is narrow.

  In the above-described embodiment, the example in which the processing method of the present invention is applied to the semiconductor wafer W has been described. However, the processing method of the present invention is similarly applied to other workpieces such as various ceramic substrates, resin substrates, and glass substrates. can do.

  In the description of the above-described embodiment, an example in which the first cutting step of step S11 is performed by the first cutting blade 28 has been described. However, the first cutting step is a laser having a wavelength that is absorptive with respect to the wafer W. The wafer W may be irradiated with the beam, and the first cutting groove 30 may be formed by ablation.

  In particular, as shown in FIG. 4B, in the processing of a wafer having a low-k film 34 on the surface of the wafer W, the first cutting step is preferably carried out by laser beam irradiation. However, the second cutting step for forming the second cutting groove 32 is preferably performed by the second cutting blade 28B.

W Semiconductor wafer S1 1st street S2 2nd street 2A 1st cutting device 2B 2nd cutting device 11 Device region 13 Peripheral surplus regions 15 and 17 Cutting line for kerf check 18 First chuck table 18B Second chuck table 22 First 1 imaging means 22B 2nd imaging means 24 1st cutting means 24B 2nd cutting means 28 1st cutting blade 28B 2nd cutting blade 30 1st cutting groove 32 2nd cutting groove

Claims (4)

A processing method of a workpiece to be performed using a first cutting device and a second cutting device,
A first holding step for holding the workpiece by the first holding means of the first cutting device;
A first cutting step of cutting a workpiece held by the first holding means with a first cutting means of the first cutting device to form a plurality of first cutting grooves having a first width;
At a predetermined timing during the execution of the first cutting step, the first imaging groove having a first reference line of the first cutting device is used to image the first cutting groove, and the positional relationship with the first reference line And a first cutting groove confirmation step for confirming the first cutting groove formed in the first cutting step;
A second holding step of holding the workpiece by the second holding means of the second cutting device after performing the first cutting step;
After carrying out the second holding step, the bottom of each first cutting groove is cut by the second cutting means of the second cutting device and is the same width as the first cutting groove or narrower than the first cutting groove. A second cutting step for forming a second cutting groove having a width;
Prior to performing at least the second cutting step, a plurality of second cutting groove checking cutting lines are set in the outer peripheral surplus area where the first cutting groove is not formed on the workpiece. Steps,
In each of a plurality of predetermined timings during implementation of the second cutting step, cutting one of the set the plurality of second cutting grooves confirmation cutting line the second cutting grooves confirmation cutting line setting step The second cutting groove confirmation groove is formed, and the second image pickup means having the second reference line of the second cutting device images the second cutting groove confirmation groove to position it with the second reference line. A second cutting groove confirmation step of measuring a relationship and confirming the second cutting groove formed in the second cutting step;
Only including,
A plurality of first cutting planned lines extending in the first direction and a plurality of second cutting planned lines extending in a second direction orthogonal to the first direction are set on the workpiece. ,
The plurality of second cutting groove confirmation cutting lines are set in parallel with the first cutting planned line,
In the second cutting groove confirmation step after the second cutting groove is formed in the second cutting planned line in the second cutting step, the second cutting groove confirmation is performed after the second holding means is rotated 90 degrees. A processing method for a workpiece, characterized in that a groove is formed . The workpiece processing method according to claim 1, wherein the second cutting step is performed with a cutting blade. The second cutting grooves confirmation step, the processing method of a workpiece according to claim 1 or 2 by imaging the second cutting grooves confirmation groove to detect the width of the second cut grooves confirmation groove. The second cutting grooves confirmation step, the according to any of claims 1 to 3 for detecting the size of chipping by imaging the second cutting grooves confirmation grooves generated in the second cut grooves confirmed groove Processing method of the workpiece.

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