JP2022040746A - Wafer processing method - Google Patents

Abstract

To easily and accurately determine positions of individual device chips formed by dividing a wafer.SOLUTION: A wafer processing method divides a wafer into individual device chips using a cutting device including: a chuck table that holds the wafer with a surface on which, multiple planned division lines are set; and a cutting unit equipped with a cutting blade. The wafer processing method includes: a holding step of attaching the wafer to an adhesive tape and suction-holding the wafer on the chuck table; and a cutting step of cutting the wafer by repeating steps of positioning the cutting blade onto an outer peripheral side of the wafer, and lowering the cutting blade into contact with the adhesive tape, cutting the wafer by the cutting blade, and raising the cutting blade. The cutting step forms, on the adhesive tape, a plurality of standard contact marks, and a plurality of reference contact marks extending with a length different from that of the standard contact marks; and forms two or more of the standard contact marks between the plurality of adjacent reference contact marks.SELECTED DRAWING: Figure 5

Description

The present invention relates to a wafer processing method for processing a wafer that is integrated with an adhesive tape and an annular frame and becomes a part of a frame unit.

In the manufacturing process of device chips mounted on electronic devices, first, a plurality of planned division lines (streets) intersecting each other are set on the surface of a wafer formed of a semiconductor material. Then, devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed in each area partitioned by the planned division line. After that, the wafer is ground from the back surface side to make it thinner, and the wafer is divided along the planned division line to obtain a plurality of device chips.

A cutting device or the like for cutting a wafer with an annular cutting blade is used for dividing the wafer (see Patent Document 1). The cutting blade is provided with an annular cutting blade on the outer peripheral portion, and when the cutting blade is rotated to cut into the wafer along the planned division line, a cutting groove is formed in the wafer.

An adhesive tape called a dicing tape is attached to the back surface side of the wafer before it is carried into the cutting device, and an inner peripheral portion of an annular frame made of metal or the like is attached to the outer peripheral portion of the adhesive tape. And the frame unit is formed. The device chip formed by cutting the wafer that became a part of the frame unit is held as it is on the adhesive tape. Subsequent expansion of the adhesive tape radially outward inside the opening of the annular frame widens the spacing between the individual device chips, facilitating pick-up of the device chips.

When a wafer is cut with a cutting blade, a chip called chipping may occur at an end portion of the surface of the wafer in contact with a cutting groove. Therefore, chipping may remain at the end of the device chip formed by dividing the wafer. If a large chipping is formed on the device chip, cracks may progress from the chipping to reach the device, the wiring layer, or the like. Therefore, in order to eliminate device chips that are defective products in advance, an inspection process of observing the surface of the wafer after cutting is performed.

In the inspection process, the surface of the wafer is observed along the cutting groove to detect the presence or absence of chipping larger than the allowable size. Then, when a chipping having a size that makes the device chip a defective product is detected, the position of the device chip on which the chipping is formed is recorded on the wafer. Then, when the formed plurality of device chips are picked up from the adhesive tape, only the non-defective device chips are picked up without picking up the defective device chips at the recorded positions.

Japanese Unexamined Patent Publication No. 2000-87282

In the inspection step, a worker conveys a wafer that has been cut to an inspection device equipped with a microscope, and the worker observes the surface of the wafer with the microscope. Then, when chipping exceeding a predetermined size is detected, the operator records the position of the device chip on which the chipping is formed.

Devices are formed in a matrix on the surface of the wafer, and when the wafer is divided, device chips arranged in a matrix are formed on the adhesive tape. Therefore, when a defective device chip is detected, the operator identifies the device chip in the row direction and the device chip in the column direction, and records the position.

However, as the devices formed on the surface of the wafer become smaller and the number of devices formed increases, the number of defective device chips in the row direction and the number in the column direction are determined. The effort to count accurately increases exponentially. In addition, there is a possibility that the position of the defective device chip may be specified incorrectly and the incorrect position may be recorded. Further, in the work of specifying the device chip that is not picked up based on the recorded position, there is a possibility that the position is misidentified and the specification is mistaken.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a wafer processing method capable of easily and accurately specifying the position of each device chip formed by dividing a wafer. Is.

According to one aspect of the present invention, a plurality of first scheduled division lines along the first direction and a plurality of second scheduled division lines along the second direction intersecting the first direction are surfaced. A chuck table that holds a wafer in which a device is formed in each region divided by the first scheduled split line and the second scheduled split line, and the wafer held in the chuck table are cut. A method of processing a wafer that divides the wafer into individual device chips using a cutting unit equipped with a cutting blade and a cutting device provided with a cutting blade, wherein the outer peripheral portion is attached to the inner peripheral portion of the annular frame. A frame unit formed by attaching the back surface side of the wafer to a tape is placed on the upper surface of the chuck table, and the wafer is sucked and held by the chuck table via the adhesive tape, and the wafer is held. A holding step that exposes the surface side and rotates the chuck table around a table rotation axis orthogonal to the top surface to align the first direction of the wafer with the machining feed direction of the cutting device, and the rotating cutting. The blade is positioned on the outer peripheral side of the wafer above the extension of the first scheduled division line, the cutting blade is lowered and brought into contact with the adhesive tape, and the cutting blade and the chuck table are relatively machined. The process of moving in the feed direction, cutting the wafer with the cutting blade along the first scheduled division line, and raising the cutting blade is repeated along all the first scheduled division lines. A first cutting step of cutting the wafer, a rotation step of rotating the chuck table around the table rotation axis to align the second direction of the wafer with the machining feed direction, and all the second steps. A second cutting step for cutting the wafer along the planned division line of the wafer, and in the first cutting step, a plurality of first cutting steps extending outward from the outer periphery of the wafer in the first direction. The standard contact marks and a plurality of first reference contact marks extending in the first direction from the outer periphery of the wafer to the outside with a length different from that of the first standard contact marks are adhered to the outside by the cutting blade. A method for processing a wafer, characterized in that two or more first number of the first standard contact marks are formed between a plurality of the first reference contact marks formed on a tape and adjacent to each other. Is provided.

Preferably, the plurality of the first reference contact marks are longer than the first standard contact marks.

Alternatively, preferably, in the second cutting step, the rotating cutting blade is positioned on the outer peripheral side of the wafer above the extension of the second planned division line, and the cutting blade is lowered to lower the adhesive tape. When the cutting blade and the chuck table are relatively moved in the machining feed direction to cut the wafer along the second scheduled division line with the cutting blade and raise the cutting blade. The process is repeated to cut the wafer along all the second scheduled division lines, and in the second cutting step, a plurality of second portions extending outward from the outer periphery of the wafer in the second direction. With the cutting blade, the standard contact marks of the above and a plurality of second reference contact marks extending in the second direction from the outer periphery of the wafer to the outside with a length different from that of the second standard contact marks. Two or more second numbers of the second standard contact marks are formed between the plurality of second reference contact marks formed on the adhesive tape and adjacent to each other.

More preferably, the plurality of the second standard contact marks have the same length as the plurality of the first standard contact marks, and the plurality of the second reference contact marks are a plurality of the first reference marks. The contact mark and the length are the same, and the second number matches the first number.

According to one aspect of the present invention, when a wafer is cut along a planned division line by a cutting blade, a plurality of contact marks are formed on the adhesive tape on the outside of the wafer. Specifically, a standard contact mark and a reference contact mark having a length different from the standard contact mark are formed on the adhesive tape. Here, since the guideline contact marks are arranged every time the standard contact marks are lined up in a predetermined number, the guideline is used when the surface of the wafer is observed and the inspection process is carried out after the cutting of the wafer is completed. The position of the device chip can be easily identified by using the contact marks.

For example, when specifying the number of a device chip in the row direction and the number of the device chip in the column direction, the number of all contact marks and the like lined up from the end of the wafer to the device chip is counted. It takes time and effort. On the other hand, when counting the reference contact marks lined up from the end side of the wafer to the device chip and counting the number of standard contact marks between the nearest reference contact mark and the device chip, the counting target is used. The number of contact marks can be significantly reduced.

If the number of contact marks to be counted can be reduced, mistakes are less likely to occur when counting the number of contact marks, so it is easy and accurate to specify the position of the device chip and the device chip at the recorded position. can.

Therefore, according to one aspect of the present invention, there is provided a method for processing a wafer in which the positions of individual device chips formed by dividing the wafer can be easily and accurately specified.

It is a perspective view which shows typically the cutting apparatus. It is a perspective view which shows the state of sticking a wafer to an adhesive tape schematically. It is a perspective view which shows typically the holding step. It is a perspective view which shows the state of carrying out the 1st cutting step schematically. It is a top view which shows typically the divided wafer and the adhesive tape which formed the contact mark. It is a flowchart explaining the flow of each step of the wafer processing method which concerns on embodiment.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. The wafer processing method according to the present embodiment is a wafer processing method for dividing a wafer into individual device chips by using a cutting device for cutting a workpiece such as a wafer made of a semiconductor. FIG. 1 is a perspective view schematically showing a cutting device 2. FIG. 2 and the like include a perspective view schematically showing the wafer 1. Further, FIG. 4 includes a perspective view schematically showing a cutting unit 10 provided inside the cutting device 2.

First, the cutting device 2 will be described. The cutting device 2 includes a main body 4 that accommodates various components in the exterior cover 8. On the front surface of the exterior cover 8 of the cutting device 2, a display 6 with a touch panel which also functions as a display monitor for displaying various information and an input interface used by an operator for inputting various commands is provided. The display 6 with a touch panel displays an operation screen for inputting various commands, an operating status of the cutting device 2, an captured image obtained by imaging a workpiece such as a wafer 1, and the like.

On the front side of the exterior cover 8, a cassette mounting table 14 on which a cassette accommodating a plurality of wafers 1 as a workpiece is placed is provided. The cutting device 2 includes a transfer unit (not shown) for carrying out the wafer 1 from a cassette (not shown) mounted on the cassette mounting table 14. The cassette mounting table 14 can be raised and lowered as appropriate so that the height of the wafer 1 to be carried out matches the height of the grip portion of the transfer unit.

The transport unit carries out the wafer 1 housed in the cassette placed on the cassette mounting table 14 from the cassette and transports the wafer 1 to the inner region of the exterior cover 8. Inside the exterior cover 8, a chuck table 12 that sucks and holds the wafer 1 and a cutting unit 10 that cuts the wafer 1 held by the chuck table 12 are provided.

The chuck table 12 is provided with a porous member having the same diameter as the wafer 1 on the upper surface 12a. The porous member is connected to a suction source (not shown). When the wafer 1 is placed on the porous member and the suction source is operated, the wafer 1 is sucked and held by the chuck table 12. Further, on the outside of the upper surface 12a of the chuck table 12, a plurality of clamps 12b for gripping the annular frame 7 (see FIG. 2 and the like) described later are provided.

FIG. 4 includes a perspective view schematically showing the cutting unit 10. The cutting unit 10 includes a cylindrical spindle housing 16 that houses a spindle 22 having a cutting blade 18 mounted at its tip. The spindle housing 16 accommodates a spindle 22 having a rotation axis substantially parallel to the Y-axis direction so as to rotate.

The cutting blade 18 includes an annular base 18a made of aluminum or the like, and an annular cutting edge 18b fixed to the outer peripheral portion of the base 18a. The cutting edge 18b is formed, for example, by fixing abrasive grains such as diamond with a binder such as resin or metal.

A rotary drive source (not shown) such as a motor is connected to the base end side of the spindle 22. When the rotary drive source is operated, the cutting blade 18 mounted on the tip end side of the spindle 22 rotates together with the spindle 22. A blade cover 24 that covers the cutting blade 18 from above is provided on the tip end side of the spindle housing 16. The blade cover 24 is fixed to the tip end side of the spindle housing 16.

A pair of nozzles 20 arranged so as to sandwich the cutting blade 18 in the Y-axis direction are provided at the lower ends of the blade cover 24, respectively. When cutting the wafer 1, cutting water is supplied to the cutting blade 18 and the wafer 1 from the pair of nozzles 20. As the cutting water, for example, water (pure water), a liquid obtained by adding a chemical to water, or the like is used.

The cutting device 2 includes a moving mechanism capable of moving the chuck table 12 and the cutting unit 10 relatively in a direction parallel to the upper surface 12a of the chuck table 12. The moving mechanism includes an X-axis direction moving mechanism (not shown) capable of relatively moving the chuck table 12 and the like in the X-axis direction (machining feed direction) and a Y-axis direction (indexing feed direction) orthogonal to the X-axis direction. It is composed of a Y-axis direction movement mechanism (not shown) that can move relatively.

Further, the cutting device 2 includes an elevating mechanism (not shown) for raising and lowering the cutting unit 10 along the Z-axis direction perpendicular to the X-axis direction and the Y-axis direction. The X-axis direction moving mechanism, the Y-axis direction moving mechanism, and the elevating mechanism are realized by, for example, a ball screw type moving mechanism.

Next, the wafer 1 to be cut by the cutting device 2 will be described. FIG. 2 includes a perspective view schematically showing the wafer 1. The wafer 1 is, for example, a disc-shaped wafer made of silicon (Si), silicon carbide (SiC), gallium nitride (GaN), or other semiconductor material. Alternatively, the wafer 1 may be made of a material such as a double oxide such as lithium tantalate (LT) and lithium niobate (LN).

On the surface 1a of the wafer 1, a plurality of first planned division lines 3a along the first direction A and a plurality of second planned division lines along the second direction B intersecting the first direction A. Line 3b is set. Then, devices 5 such as ICs and LSIs are formed in each region of the surface 1a of the wafer 1 partitioned by the first scheduled division line 3a and the second scheduled division line 3b. Then, by dividing the wafer 1 along the planned division lines 3a and 3b, individual device chips can be formed.

The wafer 1 may be a non-circular wafer made of a semiconductor material such as silicon, and the material, shape, structure, etc. of the wafer 1 are not limited. In the wafer processing method according to the present embodiment, for example, a rectangular substrate made of a material such as ceramics, resin, metal, or various types of glass may be cut. Further, there are no restrictions on the type, quantity, arrangement, etc. of the device 5.

An adhesive tape 9 having an outer peripheral portion attached to the inner peripheral portion of the annular frame 7 is previously attached to the back surface 1b side of the wafer 1. That is, the wafer 1 is integrated with the adhesive tape 9 and the annular frame 7 and becomes a part of the frame unit 11. Then, the wafer 1 is housed in a cassette in the state of the frame unit 11, is carried into the cutting device 2, and is cut.

When cutting the wafer 1 with the cutting blade 18, the height position of the cutting unit 10 is adjusted so that the lower end of the cutting blade 18b reaches the height position between the upper surface and the lower surface of the adhesive tape 9. .. Then, when the rotating cutting blade 18 is cut into the wafer 1 along the scheduled division lines 3a and 3b to cut the wafer 1, a cutting groove 13 (see FIG. 4) is formed in the wafer 1 and the wafer 1 is formed. Is split.

At this time, the formed individual device chips are held as they are on the adhesive tape 9. Therefore, when the frame unit 11 is formed, the individual device chips formed from the wafer 1 can be easily handled. Further, after cutting the wafer 1, when the adhesive tape 9 is expanded radially outward inside the opening 7a of the annular frame 7, the distance between the formed device chips is widened, and the individual device chips are picked up from the adhesive tape 9. Becomes easier.

By the way, when the wafer 1 is cut by the cutting blade 18, a chip called chipping may occur at the end portion of the surface 1a of the wafer 1 in contact with the cutting groove 13. Therefore, chipping may remain at the end of the device chip formed by dividing the wafer 1. If a large chipping is formed on the device chip, cracks may progress from the chipping to reach the device, the wiring layer, or the like. Therefore, in order to eliminate device chips that are defective in advance, an inspection step of observing the surface 1a of the wafer 1 after cutting is performed.

Devices 5 are formed in a matrix on the surface 1a of the wafer 1, and when the wafer 1 is divided, device chips arranged in a matrix are formed on the adhesive tape 9. When a chipping of a size that makes the device chip a defective product is detected, the position of the device chip on which the chipping is formed is recorded on the wafer 1.

Here, a great deal of effort is required to accurately count the number of the defective device chip in the row direction and the number in the column direction. In addition, the position of the defective device chip may be misidentified and the incorrect position may be recorded. Further, in the work of identifying the device chip that is not picked up based on the recorded position, there is a possibility that the identification may be erroneous.

Therefore, in the wafer processing method according to the present embodiment, the cutting blade formed on the adhesive tape 9 is formed so that the position of a specific device chip can be easily specified among a plurality of device chips formed by dividing the wafer. The contact marks of 18 are devised. Hereinafter, the wafer processing method according to the present embodiment will be described in detail. FIG. 6 is a flowchart schematically showing the flow of each step of the wafer processing method according to the present embodiment.

In the wafer processing method according to the present embodiment, first, the frame unit 11 including the wafer 1 is carried into the cutting device 2, placed on the upper surface 12a of the chuck table 12, and the wafer 1 is sucked and held by the chuck table 12. Hold step S10 is carried out. FIG. 3 is a perspective view schematically showing the frame unit 11 including the wafer 1 sucked and held by the chuck table 12. In FIG. 3, the clamp 12b of the chuck table 12 is omitted.

In the holding step S10, the annular frame 7 is sandwiched by the clamp 12b, the wafer 1 is sucked and held by the chuck table 12 via the adhesive tape 9, and the surface 1a side of the wafer 1 is exposed upward. After that, the chuck table 12 is rotated around a table rotation axis perpendicular to the upper surface 12a, and the first division scheduled line 3a along the first direction A of the wafer 1 is the X axis which is the machining feed direction in the cutting device 2. Align with the direction.

Following the holding step S10, a first cutting step S20 for cutting the wafer 1 along all the first scheduled division lines 3a is performed. FIG. 4 is a perspective view schematically showing the first cutting step S20. In the first cutting step S20, first, the spindle 22 is rotated, and the cutting blade 18 mounted on the tip of the spindle 22 is rotated at a rotation speed of about 30,000 rotations per minute.

Then, the chuck table 12 (not shown in FIG. 4) for holding the wafer 1 and the cutting unit 10 are moved, and the cutting blade 18b of the rotating cutting blade 18 is placed on the outer peripheral side of the wafer 1 as the first scheduled division line. Positioned above the extension of 3a.

Then, by operating the elevating mechanism to lower the cutting unit 10, the cutting blade 18 is lowered, and the cutting blade 18 is brought into contact with the adhesive tape 9. At this time, the cutting edge 18b of the rotating cutting blade 18 cuts into the adhesive tape 9, and a contact mark is formed on the adhesive tape 9. The height of the cutting unit 10 is such that the lower end of the cutting edge 18b is positioned at a height position between the upper surface and the lower surface of the adhesive tape 9.

Next, the chuck table 12 and the cutting unit 10 are machined and fed by operating the X-axis direction moving mechanism. That is, the cutting blade 18 and the chuck table 12 are relatively moved in the X-axis direction (machining feed direction), and the wafer 1 is cut along the first scheduled division line 3a by the cutting blade 18. At this time, a cutting groove 13 is formed on the wafer 1 along the first scheduled division line 3a, and the wafer 1 is divided by the cutting groove 13.

The cutting blade 18 that has cut the wafer 1 is stopped after the wafer 1 in order to sufficiently cut the wafer 1. Therefore, the cutting blade 18 is cut into the adhesive tape 9 even on the outside of the wafer 1, and contact marks are formed. After that, the cutting blade 18 is raised.

In the first cutting step S20, this series of steps is repeated in order to cut the wafer 1 along all the first scheduled division lines 3a. That is, the cutting blade 18b of the cutting blade 18 is positioned on the outer peripheral side of the wafer 1 above the extension line of the next first scheduled division line 3a, and the cutting blade 18 is lowered. Then, the wafer 1 is cut by the cutting blade 18, and the cutting blade 18 is raised. In this way, when the wafer 1 is cut along all the first scheduled division lines 3a, the first cutting step S20 is completed.

Next, a rotation step S30 is performed in which the chuck table 12 is rotated around the table rotation axis to align the second direction B of the wafer 1 with the X-axis direction (machining feed direction) of the cutting device 2. Then, similarly to the first cutting step S20, the second cutting step S40 for cutting the wafer 1 along all the second scheduled division lines 3b is performed.

That is, in the second cutting step S40, the rotating cutting blade 18 is positioned on the outer peripheral side of the wafer 1 above the extension line of the second scheduled division line 3b, and the cutting blade 18 is lowered to bring it into contact with the adhesive tape 9. .. Then, the cutting blade 18 and the chuck table 12 are relatively moved in the X-axis direction (machining feed direction), the wafer 1 is cut by the cutting blade 18 along the second scheduled division line 3b, and the cutting blade 18 is cut. To raise. This series of steps is repeated to cut the wafer 1 along all the second scheduled division lines 3b.

Then, in the wafer processing method according to the present embodiment, the length of the contact marks formed on the adhesive tape 9 on the outside of the wafer 1 in the first cutting step S20 and the second cutting step S40 is devised. Apply. That is, two types of contact marks having different lengths are formed on the adhesive tape 9 in a predetermined arrangement so that the operator can distinguish them.

The length of the contact mark can be controlled by the position where the cutting blade 18 is lowered when cutting the wafer 1. For example, when the cutting blade 18 is lowered at a position relatively far from the wafer 1, a relatively long contact mark is formed, and when the cutting blade 18 is lowered at a position relatively close to the wafer 1, a relatively short contact mark is formed. To.

Generally, in order to cut the cutting blade 18 into the wafer 1 under stable machining conditions, it is necessary to accelerate the chuck table 12 and the like so as to have a predetermined machining feed rate before cutting into the wafer 1. Therefore, it is necessary to lower the cutting blade 18 onto the adhesive tape 9 at a position outside the wafer 1 at a required approach distance.

On the other hand, when the cutting blade 18 is lowered to the adhesive tape 9 at a position outside the wafer 1 far beyond the required approach distance, the chuck table 12 and the like reach a predetermined machining feed rate, and then the wafer 1 It takes a long time for the cutting blade 18 to cut. That is, if the cutting blade 18 is lowered at a position far away from the wafer 1, it takes a long time to complete the cutting of the wafer 1, and the processing efficiency is lowered.

Therefore, in the wafer 1, the cutting blade 18 is generally lowered to the adhesive tape 9 at a position slightly exceeding the required approach distance. Therefore, the lengths of the contact marks of the cutting blades 18 formed on the adhesive tape 9 tend to be substantially the same regardless of the lengths of the scheduled division lines 3a and 3b and the positions on the wafer 1, and the operator can visually recognize the contact marks. It is difficult to distinguish them.

Therefore, in the wafer processing method according to the present embodiment, a large approach distance is secured when cutting a part of the planned division lines 3a and 3b with the cutting blade 18, and contact marks that can be distinguished from other contact marks are adhered. Formed on tape 9.

FIG. 5 is a top view schematically showing the wafer 1 cut by the cutting blade 18. As shown in FIG. 5, relatively long contact marks and relatively short contact marks are regularly arranged on the adhesive tape 9 outside the outer peripheral 1c of the wafer 1. For example, this relatively long contact mark is referred to as a reference contact mark 17, and a relatively short contact mark is referred to as a standard contact mark 15. However, the lengths of the reference contact mark 17 and the standard contact mark 15 are not limited to this, and the reference contact mark 17 may be relatively short and the standard contact mark 15 may be relatively long.

Here, the arrangement of the reference contact mark 17 and the standard contact mark 15 will be described. On the adhesive tape 9, the reference contact marks 17 are arranged after the standard contact marks 15 are arranged in a predetermined number, and the next reference contact marks 17 are arranged after the standard contact marks 15 are arranged in a predetermined number. .. In the example shown in FIG. 5, four standard contact marks 15 are arranged between a plurality of reference contact marks 17 adjacent to each other. The positions of the individual device chips 19 formed from the wafer 1 divided by the cutting groove 13 can be easily and accurately identified by counting the standard contact marks 15 and the reference contact marks 17.

For example, the device tip 21 in FIG. 5 is adjacent to the cutting groove 13 indicated by the second reference contact mark 17 in the first direction A, and is indicated by the first reference contact mark 17 in the second direction B. It is adjacent to the cutting groove 13. The first reference contact mark 17 is counted as the fifth contact mark, and the second reference contact mark 17 is counted as the tenth contact mark. Therefore, the position of the device chip 21 is the tenth in the first direction A and the fifth in the second direction B.

Here, when the contact marks formed on the adhesive tape 9 are indistinguishable from each other, 10 contact marks and a first contact mark along the first direction A are used to identify the position of the device chip 21. The number of contact marks and 5 contact marks along the direction B of 2 is counted. On the other hand, when the reference contact marks 17 are formed on the adhesive tape 9, two reference contact marks 17 are formed along the first direction A and one reference contact mark is formed along the second direction B. The position of the device chip 21 can be specified only by counting the number of 17.

Further, for example, the device chip 23 in FIG. 5 is adjacent to the cutting groove 13 indicated by the third reference contact mark 17 in the first direction A, and the first reference contact mark 17 in the second direction B. It is adjacent to the cutting groove 13 indicated by the second standard contact mark 15 counting from. Therefore, the position of the device chip 23 is the 15th position in the first direction A, and is the 7th position obtained by adding 2 to 5 in the second direction B.

Here, when the contact marks formed on the adhesive tape 9 are indistinguishable from each other, 15 contact marks and a first contact mark along the first direction A are used to identify the position of the device chip 23. The number of contact marks and 7 contact marks along the direction B of 2 is counted. On the other hand, when the reference contact marks 17 are formed on the adhesive tape 9, three reference contact marks 17 along the first direction A and one reference contact mark along the second direction B. The position of the device chip 23 can be specified only by counting the number of 17 and the two standard contact marks 15.

As described above, according to the wafer processing method according to the present embodiment, a plurality of standard contact marks 15 and a plurality of reference contact marks 17 are formed on the adhesive tape 9 at regular positions on the outside of the outer peripheral 1c of the wafer 1. Ru. Since the standard contact mark 15 and the reference contact mark 17 can be distinguished from each other in appearance, the position of the device chip formed on the wafer 1 can be easily and accurately specified.

In recent years, there has been a remarkable tendency for device chips to be miniaturized, and there are cases where about 100 first scheduled division lines 3a and about 100 second scheduled division lines 3b are set on the wafer 1. As described above, as the number of scheduled division lines 3a and 3b increases, the advantage of being able to reduce the number of contact marks to be counted when specifying the position of the device chip becomes remarkable.

Either a contact mark extended from the first scheduled division line 3a along the first direction A or a contact mark extended from the second scheduled division line 3b along the second direction B. However, it is not necessary to make two types of contact marks separately. If the contact marks formed on the adhesive tape 9 in only one of the first direction A and the second direction B are made of two different lengths, the contact marks are formed when the position of the device chip is specified. It is possible to reduce the trouble of counting the number of marks and the like.

Further, the case where the four standard contact marks 15 are arranged between the two adjacent reference contact marks 17 has been described, but the standard contact marks 15 arranged between the two adjacent reference contact marks 17 have been described. The number is not limited to this. However, if the number of the reference contact marks 17 becomes too large, the time and effort for counting the numbers cannot be greatly reduced. Therefore, for example, the number of the standard contact marks 15 arranged between the two reference contact marks 17 adjacent to each other is 2. The above is preferable.

Further, the number of standard contact marks 15 arranged between the two adjacent reference contact marks 17 is more preferably any one of 4, 9, 19, and 24. With this number, the number of contact marks indicated by one of the reference contact marks 17 is any of 5, 10, 20, and 25, and the operator can specify the number of contact marks when specifying the position of the target device chip. Will be easier to calculate.

Further, using FIG. 5, the number of the first scheduled division lines 3a and the number of the second scheduled division lines 3b match, and the intervals between the first scheduled division lines 3a adjacent to each other and the intervals adjacent to each other are adjacent to each other. The case where the intervals of the second scheduled division lines 3b match has been described. Further, FIG. 5 shows a case where the first scheduled division line 3a and the second scheduled division line 3b are orthogonal to each other. However, the wafer 1 processed by the wafer processing method according to the present embodiment is not limited to this.

For example, the device chip 19 formed may be a rectangle, a rhombus, or a parallelogram instead of a square. That is, the first scheduled division line 3a and the second scheduled division line 3b may not be orthogonal to each other, and the intervals may not be the same.

The number of standard contact marks 15 arranged between the two adjacent reference contact marks 17 need not be the same in the first direction A and the second direction B. Based on the shape of the device chip 19 to be formed, it is preferable that the arrangement of the reference contact marks 17 and the standard contact marks 15 is determined in an easily countable number in each of the first direction A and the second direction B. ..

However, especially when the device chip 19 is square, the number of standard contact marks 15 arranged between the two adjacent reference contact marks 17 is one in the first direction A and the second direction B. If this is done, the operator will have less confusion in identifying the position of the device chip 19.

Further, in FIG. 5, the case where the reference contact mark 17 is longer than the standard contact mark 15 has been mainly described, but the standard contact mark 15 may be longer than the standard contact mark 17. However, when the reference contact marks 17 formed in a relatively small number are longer than the standard contact marks 15, there are relatively few contact marks that exceed the required approach distance of the cutting blade 18 and are formed on the adhesive tape 9. Will be. Therefore, the time required for cutting the wafer 1 is relatively short.

It should be noted that the plurality of standard contact marks 15 formed on the adhesive tape 9 do not need to have the same length, and the plurality of reference contact marks 17 formed on the adhesive tape 9 also need to have the same length. do not have. The lengths of the standard contact mark 15 and the reference contact mark 17 may be adjusted based on the position where each is formed or the like. It is sufficient if the standard contact marks 15 and the reference contact marks 17 have different lengths so that they can be distinguished from each other, and it is not necessary that the respective lengths are unified.

Further, the length of the reference contact mark 17 may be different from the length of the standard contact mark 15 to the extent that it can be visually distinguished from the standard contact mark 15. For example, the length of the reference contact mark 17 is preferably twice or more, or less than half, the length of the standard contact mark 15 adjacent to the reference contact mark 17.

Further, the reference contact marks 17 having different lengths from the standard contact marks 15 may be formed on either the front side or the rear side in the machining feed direction of the wafer 1. In this case, since the number of long contact marks formed on the adhesive tape 9 can be reduced as compared with the case where the reference contact marks 17 are formed on both of them, the time required for cutting the wafer 1 is relatively short.

On the other hand, the reference contact marks 17 having different lengths from the standard contact marks 15 may be formed on both the front side and the rear side in the machining feed direction of the wafer 1. In this case, since the number of contact marks can be counted by selecting and referring to the reference contact marks 17 close to the device chip 19 whose position is to be specified, the movement of the line of sight of the operator is small, and the position can be specified by the operator. The accuracy of can be improved.

When the reference contact mark 17 is formed on the front side of the wafer 1 in the machining feed direction, the cutting blade 18 is located farther from the wafer 1 than the approach distance required to accelerate the chuck table 12 or the like to a predetermined speed. Is lowered onto the adhesive tape 9. On the other hand, when the reference contact mark 17 is formed on the rear side of the wafer 1 in the machining feed direction, the braking distance required to stop the chuck table 12 and the like after the cutting blade 18 finishes cutting the wafer 1 is increased. Also raises the cutting blade 18 at a position away from the wafer 1.

Here, when the wafer 1 is cut by the cutting blade 18, the cutting blade 18 cuts into the adhesive tape 9 even below the wafer 1. Therefore, contact marks are formed on the adhesive tape 9 even in the region overlapping the cutting groove 13 formed on the wafer 1. The standard contact mark 15 and the standard contact mark 17 are continuous formed on the adhesive tape 9 until the cutting blade 18 descends to the adhesive tape 9, cuts the wafer 1, and rises from the adhesive tape 9. The contact mark is a portion outside the outer circumference 1c of the wafer 1.

In other words, the series of contact marks formed on the adhesive tape 9 when the wafer 1 is cut on one scheduled division line 3a, 3b is larger than the standard contact mark 15 or the reference contact mark 17 and the outer circumference 1c of the wafer 1. Including the inner part. Then, the standard contact mark 15 or the reference contact mark 17 and the portion inside the outer circumference 1c of the wafer 1 are continuous.

To summarize the above description, in the first cutting step S20, a plurality of first standard contact marks 15 extending outward from the outer peripheral 1c of the wafer 1 in the first direction A are formed on the adhesive tape 9 by the cutting blade 18. do. Further, a plurality of first guideline contact marks 17 extending outward from the outer peripheral 1c of the wafer 1 in a length different from that of the first standard contact marks 15 in the first direction A are formed on the adhesive tape 9 by a cutting blade 18. Form. Then, two or more first standard contact marks 15 are formed between the plurality of first reference contact marks 17 adjacent to each other.

In the second cutting step S40, a plurality of second standard contact marks 15 extending outward from the outer peripheral 1c of the wafer 1 in the second direction B are formed on the adhesive tape 9 by the cutting blade 18. Further, a plurality of second reference contact marks 17 extending outward from the outer peripheral 1c of the wafer 1 in a length different from that of the second standard contact mark 15 in the second direction B are formed on the adhesive tape 9 by the cutting blade 18. Form. Then, two or more second standard contact marks 15 are formed between the plurality of second reference contact marks 17 adjacent to each other.

Here, the plurality of the second standard contact marks 15 have the same length as the plurality of the first standard contact marks 15, and the plurality of the second reference contact marks 17 are the plurality of the first reference marks. It is preferable that the length is the same as that of the contact mark 17, and the second number matches the first number. In this case, since the characteristics of the standard contact mark 15 and the reference contact mark 17 are unified throughout the frame unit 11, the work accuracy of the operator who counts the number of contact marks in order to specify the position of the device chip is improved.

The present invention is not limited to the description of the above embodiment, and can be modified in various ways. For example, in the above embodiment, when two types of contact marks having different lengths, a standard contact mark 15 and a reference contact mark 17, are formed on the adhesive tape 9 in a portion outside the outer peripheral 1c of the wafer 1. However, one aspect of the present invention is not limited to this. That is, three or more types of contact marks may be formed on the portion of the adhesive tape 9 outside the outer circumference 1c of the wafer 1.

For example, in addition to the standard contact mark 15 and the reference contact mark 17, special reference contact marks having different lengths from the standard contact mark 15 and the reference contact mark 17 may be formed on the adhesive tape 9. For example, when the reference contact mark 17 is formed with a length of about twice the standard contact mark 15, the special reference contact mark may be formed with a length of about three times the standard contact mark 15.

Then, for example, in the first direction A or the second direction B, four standard contact marks 15 are lined up, then one reference contact mark 17 is arranged, and then four standard contact marks 15 are lined up next. Place one special guideline contact mark on each. When this is repeated to form contact marks on the adhesive tape 9, the reference contact marks 17 indicate the presence of 5 contact marks, and the special reference contact marks indicate the presence of 10 contact marks.

Specifically, when the device chip whose position is to be specified is adjacent to the third standard contact mark 15 counting from the reference contact mark 17 that appears next to the six special reference contact marks along the first direction A. It can be seen that the position of the device chip is 68th in the first direction A. When three or more types of contact marks are formed on the adhesive tape 9 in this way, the operator can more easily and surely detect the position of the device chip.

In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

1 Wafer 1a Front surface 1b Back surface 1c Outer circumference 3a, 3b Scheduled division line 5 Device 7 Circular frame 7a Opening 9 Adhesive tape 11 Frame unit 13 Cutting groove 15 Standard contact mark 17 Estimated contact mark 19, 21, 23 Device chip 2 Cutting device 4 Main body 6 Display with touch panel 8 Exterior cover 10 Cutting unit 12 Chuck table 12a Top surface 12b Clamp 14 Cassette mounting stand 16 Spindle housing 18 Cutting blade 18a Base 18b Cutting blade 20 Nozzle 22 Spindle 24 Blade cover

Claims (4)

A plurality of first scheduled split lines along the first direction and a plurality of second scheduled split lines along the second direction intersecting the first direction are set on the surface and the first scheduled split line is set. A chuck table holding a wafer in which a device is formed in each region partitioned by a line and a second scheduled division line, and a cutting unit provided with a cutting blade for cutting the wafer held in the chuck table. A method for processing a wafer, which divides the wafer into individual device chips using a cutting device provided with.
A frame unit formed by attaching the back surface side of the wafer to an adhesive tape having an outer peripheral portion attached to the inner peripheral portion of the annular frame is placed on the upper surface of the chuck table, and the wafer is placed on the chuck table. Is sucked and held through the adhesive tape, the surface side of the wafer is exposed, and the chuck table is rotated around a table rotation axis orthogonal to the upper surface to cut the first direction of the wafer. A holding step that matches the machining feed direction of the device,
The rotating cutting blade is positioned on the outer peripheral side of the wafer above the extension of the first scheduled division line, the cutting blade is lowered and brought into contact with the adhesive tape, and the cutting blade and the chuck table are relative to each other. The process of moving the wafer in the machining feed direction, cutting the wafer along the first scheduled division line with the cutting blade, and raising the cutting blade is repeated to complete the first division schedule. The first cutting step of cutting the wafer along the line,
A rotation step of rotating the chuck table around the table rotation axis to align the second direction of the wafer with the machining feed direction.
A second cutting step, in which the wafer is cut along all the second scheduled split lines, is provided.
In the first cutting step, a plurality of first standard contact marks extending outward from the outer circumference of the wafer in the first direction are different from the first standard contact marks extending outward from the outer circumference of the wafer. A plurality of first reference contact marks extending in the first direction in length are formed on the adhesive tape with the cutting blade.
A method for processing a wafer, characterized in that two or more first numbers of the first standard contact marks are formed between a plurality of the first reference contact marks adjacent to each other. The wafer processing method according to claim 1, wherein the plurality of first reference contact marks are longer than the first standard contact marks. In the second cutting step, the rotating cutting blade is positioned on the outer peripheral side of the wafer above the extension of the second scheduled division line, and the cutting blade is lowered to bring it into contact with the adhesive tape. The process of moving the cutting blade and the chuck table relatively in the machining feed direction, cutting the wafer along the second scheduled division line with the cutting blade, and raising the cutting blade is repeated. The wafer is cut along all the second scheduled split lines.
In the second cutting step, the plurality of second standard contact marks extending outward from the outer circumference of the wafer in the second direction are different from the second standard contact marks extending outward from the outer circumference of the wafer. A plurality of second reference contact marks extending in the second direction in length are formed on the adhesive tape with the cutting blade.
The processing of a wafer according to claim 1, wherein two or more second numbers of the second standard contact marks are formed between a plurality of the second reference contact marks adjacent to each other. Method. The plurality of the second standard contact marks are the same length as the plurality of the first standard contact marks.
The plurality of the second reference contact marks have the same length as the plurality of the first reference contact marks.
The wafer processing method according to claim 3, wherein the second number matches the first number.

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