JP6943389B2 - Processing method of work piece - Google Patents

Description

The present invention relates to a processing method for processing a workpiece including a wafer on which a device is formed on the surface.

In the manufacturing process of device chips used in electronic devices such as mobile phones and personal computers, first, a plurality of intersecting planned division lines are set on the surface of a wafer made of a material such as a semiconductor. Then, devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed in each area partitioned by the planned division line. Further, the device chip can be formed by thinning the wafer to a predetermined thickness and then dividing the wafer along the planned division line.

In recent years, a mounting technique called flip-chip bonding has been put into practical use in order to save space in a region required for mounting a device chip on a predetermined mounting target. In flip-chip bonding, metal protrusions called a plurality of bumps having a height of about 10 μm to 100 μm are formed on the surface side of the device via a wiring substrate, and these bumps are made to face the electrodes formed on the mounting target. It is a mounting technology that directly joins. The bump functions as a terminal of the device chip and is connected to the device via a wiring board and a thin metal wire.

Further, as a semiconductor packaging technology, bumps are formed directly on the device surface without internal wiring by thin metal wires, the wafer surface and the bumps are covered with a sealing material and sealed, and the wafers are individually sealed. The technology of dividing into device chips has been put into practical use. The packaging technique is called WL-CSP (Wafer-level Chip Size Package) (see Patent Document 1).

Since the heights of the plurality of bumps formed on the surface of the wafer are not always uniform, even if the plurality of bumps are directly bonded to the electrodes formed on the mounting target of the device chip, they are uniformly bonded. Is not easy. Therefore, the upper part of the sealing material and the upper part of the bump are cut with a tool using a tool cutting device equipped with a cutting tool having a cutting edge made of diamond to thin the sealing material and reduce the height of the bump. A processing method for making the uniform uniform has been developed (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2001-7135 Japanese Unexamined Patent Publication No. 2000-173954

The cutting tool for cutting the surface side of the wafer on which the sealing material and the bump are formed cuts the sealing material having high processing resistance at the time of cutting the cutting material and the bump made of metal at the same time. To cut. Therefore, the machining load and machining heat generated by the cutting of the tool strongly act on the tool, and the cutting edge of the tool is severely worn.

Since further tool cutting cannot be performed with a heavily worn tool, the tool must be replaced frequently. The tool cutting device cannot be used while the tool is being replaced, and the replacement tool is very expensive. Therefore, the machining efficiency of the tool cutting device becomes low, which causes a problem.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for machining a workpiece that can suppress wear of a cutting edge of a tool tool and improve machining efficiency. ..

According to one aspect of the present invention, a chuck table for holding a work piece, a tool bite tool having a cutting edge made of diamond for cutting the surface of the work piece held on the chuck table with a tool bite, and the tool bite tool. Using a tool cutting device including a tool wheel provided on the lower surface, a tool cutting unit for rotatably supporting the tool wheel, and a tool cutting device for supplying cutting liquid to the tool, the wafer and the tool. A method for processing an workpiece, which comprises tool-cutting the workpiece including a device formed on the surface of a wafer, a bump on the device, the device, and a sealing material on the bump. The chuck table includes a holding step of holding the workpiece and a tool cutting step of cutting the sealing material with a tool to expose the bump from the sealing material, and the tool cutting step is a tool cutting. Provided is a method for processing a work piece, which is carried out in a state where the temperature of the environment in which the device is installed is set to −5 ° C. to + 10 ° C.

In the method for machining an workpiece according to one aspect of the present invention, a cutting tool having a cutting edge for cutting the surface of the workpiece, a tool wheel provided with the cutting tool on the lower surface, and a cutting edge of the cutting tool are used for cutting. A tool cutting device including a cutting fluid supply device for supplying the liquid is used.

For example, when the temperature control step is not performed, the temperature of the environment of the device chip manufacturing factory where the tool cutting device is installed is generally set to room temperature of about 20 ° C. to 25 ° C. On the other hand, in the method for processing a workpiece according to one aspect of the present invention, the temperature of the environment in which the tool cutting device is installed is lowered when cutting the tool for the workpiece.

Therefore, the heat generated by the cutting of the tool is easily diffused to the environment, and the temperature rise of the tool is suppressed. However, if the temperature of the environment in which the tool cutting device is installed is set lower, the liquid such as the cutting fluid used in the tool cutting device may freeze. Therefore, if the temperature of the environment is set to -5 ° C to 10 ° C, which allows the cutting fluid to be supplied to the cutting tool without freezing, the consumption of the cutting tool can be suppressed, the frequency of replacement of the cutting tool is reduced, and the cutting device is machined. Efficiency can be increased.

Therefore, the present invention provides a method for machining a workpiece that can suppress wear of the cutting edge of a tool tool and improve machining efficiency.

FIG. 1 (A) is a perspective view schematically showing a work piece provided with bumps and a sealing material on the surface, and FIG. 1 (B) is a cover provided with bumps and a sealing material on the surface. It is sectional drawing which shows typically the workpiece. It is a perspective view which shows typically the tool cutting apparatus. FIG. 3A is a side view schematically showing the tool cutting step, and FIG. 3B is a top view schematically showing the tool cutting step.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. First, the workpiece of the tool cutting apparatus according to the present embodiment will be described with reference to FIGS. 1 (A) and 1 (B). FIG. 1A is a perspective view schematically showing a work piece. The workpiece 5 includes a wafer 1, bumps 7, and a sealing material 3.

The wafer 1 is, for example, a substantially disk-shaped substrate made of a material such as silicon, SiC (silicon carbide), or other semiconductor, or a material such as sapphire, glass, or quartz. A plurality of scheduled division lines (not shown) are set in a grid pattern on the surface 1a of the wafer 1, and ICs (Integrated Circuits), LSIs (Large Scale Integration), etc. are provided in each region partitioned by the scheduled division lines. The device 7a is formed. Finally, when the wafer 1 is divided along the planned division line, individual device chips are formed.

FIG. 1B is a cross-sectional view schematically showing the workpiece 5. The bump 7 is formed of a conductive material such as metal, and serves as a terminal for a device chip formed by dividing the wafer 1. Before the wafer 1 is divided, the workpiece 5 is tool-cut by a tool-cutting device provided with a tool, and the upper part of the sealing material 3 covering the bump 7 and the upper part of the bump 7 are partially removed. Then, since the bump 7 is exposed from the sealing material 3, the bump 7 can be joined to the electrode to be mounted when the device chip is mounted on the predetermined mounting target.

Next, a tool cutting device according to one aspect of the present invention will be described with reference to FIG. FIG. 2 is a perspective view schematically showing a tool cutting device 2 for cutting a work piece 5 with a tool.

The tool cutting device 2 has a base 4 that supports each configuration. Cassette mounting bases 6a and 6b are provided on the upper surface of the front side portion of the base 4. On the cassette mounting table 6a, for example, a cassette 8a containing a workpiece 5 before cutting a tool is placed. On the cassette mounting table 6b, for example, a cassette 8b for accommodating the workpiece 5 after cutting the tool is placed. On the base 4, a transfer robot 10 that conveys the workpiece 5 adjacent to the cassette mounting tables 6a and 6b is installed.

Further, on the upper surface of the front side portion of the base 4, a positioning table 12 for determining the position of the workpiece 5 with a plurality of positioning pins, a loading mechanism (loading arm) 14 for mounting the workpiece 5 on the chuck table 20, and a cover. An unloading mechanism (unloading arm) 16 for carrying out the work piece 5 from the chuck table 20 and a washing unit 50 for washing and spin-drying the work piece 5 machined by a bite are provided.

An opening 4a is provided on the upper surface of the rear portion of the base 4. Inside the opening 4a, an X-axis moving table 18 on which a chuck table 20 for sucking and holding the workpiece 5 is mounted is provided. The X-axis movement table 18 can be moved in the X-axis direction by an X-axis direction movement mechanism (not shown). The X-axis moving table 18 has a carry-in / out area 22 on which the work piece 5 is attached / detached on the chuck table 20 and a work area 24 in which the work piece 5 sucked and held on the chuck table 20 is bite-cut. Positioned.

The upper surface of the chuck table 20 is a holding surface 20a for holding the workpiece 5. The chuck table 20 is internally provided with a suction path having one end connected to a holding surface 20a of the chuck table 20 and the other end connected to a suction source (not shown). When the suction source is operated, a negative pressure acts on the workpiece 5 placed on the holding surface 20a, and the workpiece 5 is suction-held on the chuck table 20.

Above the machining area 24, a tool cutting unit 26 for cutting the workpiece 5 with a tool is arranged. A support portion 28 is erected at the rear end of the base 4 of the tool cutting device 2, and the tool cutting unit 26 is supported by the support portion 28. A pair of Z-axis guide rails 30 extending in the Z-axis direction are provided on the front surface of the support portion 28, and a Z-axis moving plate 32 is slidably attached to each Z-axis guide rail 30.

A nut portion (not shown) is provided on the back surface side (rear surface side) of the Z-axis moving plate 32, and a Z-axis ball screw 34 parallel to the Z-axis guide rail 30 is screwed into the nut portion. ing. A Z-axis pulse motor 36 is connected to one end of the Z-axis ball screw 34. When the Z-axis ball screw 34 is rotated by the Z-axis pulse motor 36, the Z-axis moving plate 32 moves in the Z-axis direction along the Z-axis guide rail 30.

A cutting tool 26 is fixed to the lower portion on the front surface side of the Z-axis moving plate 32. If the Z-axis moving plate 32 is moved in the Z-axis direction, the tool cutting unit 26 can be moved in the Z-axis direction.

The tool cutting unit 26 includes a spindle 40 that is rotated by a motor connected to the base end side, and a tool wheel 44 that is fixed to a mount 42 arranged on the tip end side of the spindle 40 by a fixture 46. The motor is provided in the spindle housing 38, and when the motor is operated, the bite wheel 44 rotates according to the rotation of the spindle 40.

A tool tool 52 (see FIG. 3A) is mounted on the lower surface of the tool wheel 44. The cutting tool 52 is provided with a cutting edge 52a (see FIG. 3A) that comes into contact with the workpiece 5 and cuts the workpiece 5 with a tool. The cutting edge 52a is made of, for example, diamond.

The tool cutting unit 26 is lowered along the Z-axis direction, and the lower end of the cutting edge 52a is positioned at a height position reaching the bump 7 formed on the surface 1a of the wafer 1. Then, when the bite wheel 44 is rotated and the chuck table 20 is moved in the X-axis direction, the upper part of the sealing material 3 and the upper part of the bump 7 are cut by a bite, and the bump 7 is removed from the sealing material 3. Be exposed.

A cutting fluid supply device 48 (see FIG. 3B) that injects the cutting fluid 48a onto the tool tool 52 is arranged on the side of the machining region 24. The tool tool 52 bites the sealing material 3 having high machining resistance and the bump 7 made of metal. Therefore, the machining load and machining heat generated by the cutting of the tool strongly act on the tool 52, and the cutting edge 52a of the tool 52 is severely worn. Therefore, the cutting fluid 48a is supplied to the tool tool 52 by the cutting fluid supply device 48, and the machining heat is removed together with the cutting chips generated by the cutting tool cutting.

However, it is not easy to supply the cutting fluid 48a to the rotating tool 52 to efficiently remove the processing heat and cool the tool 52. Therefore, the temperature of the environment in which the tool cutting device 2 is installed is lowered to efficiently cool the tool tool 52.

In order to lower the temperature of the environment in which the tool cutting device 2 is installed, the tool cutting device 2 is installed inside the cooling chamber 54. The cooling chamber 54 includes a cooling device (not shown) such as an air controller that lowers the temperature inside the chamber. The cooling chamber 54 includes a door 54a that serves as an entrance / exit route.

Next, a processing method of the workpiece 5 according to one aspect of the present invention will be described. The processing method of the workpiece 5 is carried out by, for example, the above-mentioned cutting tool 2. The processing method of the workpiece 5 includes a holding step of holding the workpiece 5 on the chuck table 20 and a tool cutting step of cutting the sealing material 3 with a tool to expose the bump 7. Hereinafter, each step of the processing method of the workpiece 5 will be described.

First, the air controller of the cooling chamber 54, which is the environment in which the tool cutting device 2 is installed, is controlled to bring the temperature inside the cooling chamber 54 to −5 ° C. to 10 ° C. When the door 54a of the cooling chamber 54 is opened and closed, the temperature inside the cooling chamber 54 is likely to change. The housed cassette 8a is installed.

Next, the holding step will be described. In the holding step, the work piece 5 is taken out from the cassette 8a mounted on the cassette mounting table 6a by the transfer robot 10. Then, the workpiece 5 is carried into the positioning table 12, and the positioning table 12 is operated to align the center of the workpiece 5 with the center of the positioning table 12.

After that, the workpiece 5 is placed on the holding surface 20a of the chuck table 20 placed on the X-axis moving table 18 positioned in the loading / unloading region 22 by the loading mechanism (loading arm) 14. At this time, the back surface 1b side of the wafer 1 is turned downward, and the back surface 1b is brought into contact with the holding surface 20a.

After the workpiece 5 is placed on the holding surface 20a of the chuck table 20, the suction source (not shown) of the chuck table 20 is operated to apply a negative pressure to the workpiece 5, and the chuck table 20 is subjected to the negative pressure. The workpiece 5 is sucked and held. As a result, the sealing material 3 of the workpiece 5 is exposed upward.

Next, the tool cutting step will be described. After performing the holding step, the X-axis moving table 18 is moved to the machining area 24. Then, the tool wheel 44 is rotated, the tool cutting unit 26 is lowered along the Z-axis direction, and the lower end of the cutting edge 52a is positioned at a height position reaching the bump 7 of the workpiece 5. After that, when the chuck table 20 is moved in the X-axis direction, the upper portion of the sealing material 3 and the upper portion of the bump 7 of the workpiece 5 are cut by a tool tool 52, and the bump 7 is exposed from the sealing material 3. Will be done.

FIG. 3A is a side view schematically showing the tool cutting step, and FIG. 3B is a top view schematically showing the tool cutting step. When cutting the workpiece 5 with a tool, the tool 52 is injected with the cutting fluid 48a from the cutting fluid supply device 48.

After the cutting of the tool by the tool 52 is completed, the X-axis moving table 18 is moved to the loading / unloading area 22, the suction by the chuck table 20 is released, and the workpiece 5 is washed by the loading mechanism (unloading arm) 16. Carry it out to the unit 52. Then, the workpiece 5 is washed and dried by the washing unit 52. The washed workpiece 5 is housed in the cassette 8b mounted on the cassette mounting table 6b by the transfer robot 10.

In the method for processing a workpiece according to one aspect of the present invention, the temperature of the environment in which the tool cutting device 2 is installed is lowered from room temperature. Generally, the temperature of the environment of the device chip manufacturing factory where the tool cutting device 2 is installed is set to a room temperature of about 20 ° C. to 25 ° C. On the other hand, in the method for processing a workpiece according to one aspect of the present invention, the temperature of the environment in which the tool cutting device is installed is set to −5 ° C. to 10 ° C.

When the temperature of the environment is set to such a temperature, the heat generated by the cutting of the tool is easily diffused to the environment, the temperature rise of the tool is suppressed, the consumption of the tool can be suppressed, and the frequency of replacement of the tool is suppressed. Can be reduced to increase the machining efficiency of the tool cutting device.

The present invention is not limited to the description of the above embodiment, and can be implemented with various modifications. For example, in the tool cutting step, the temperature of the environment in which the tool cutting device 2 is installed may be set to −5 ° C. or lower. In this case, an anticoagulant may be mixed with each liquid so that the liquid such as the cutting liquid does not solidify inside the tool cutting device 2, and the freezing point of each liquid may be lowered. The lower the temperature of the environment, the higher the cooling efficiency of the tool tool, and the consumption of the tool tool can be suppressed.

Further, in the above embodiment, the tool cutting device 2 is installed inside the cooling chamber 54 to control the temperature inside the cooling chamber 54, but one aspect of the present invention is not limited to this. For example, a box-shaped machining chamber surrounding the periphery of the machining region 24 where the tool cutting is performed may be provided in the tool cutting device 2, and the temperature of the machining chamber may be controlled.

The structure, method, etc. 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 3 Encapsulant 5 Work piece 7 Bump 7a Device 2-bit cutting device 4 Base 4a Opening 6a, 6b Cassette mounting table 8a, 8b Cassette 10 Transfer robot 12 Positioning table 14 Loading mechanism (loading arm)
16 Unloading mechanism (unloading arm)
18 X-axis moving table 20 Chuck table 20a Holding surface 22 Carry-in / out area 24 Machining area 26 Tool cutting unit 28 Support part 30 Z-axis guide rail 32 Z-axis moving plate 34 Z-axis ball screw 36 Z-axis pulse motor 38 Spindle housing 40 Spindle 42 Mount 44 Tool Bit Cutting Wheel 46 Fixture 48 Cutting Liquid Supply Device 48a Cutting Liquid 50 Cleaning Unit 52 Tool Tool 52a Cutting Blade 54 Cooling Room

Claims (1)

A chuck table that holds the workpiece, a tool with a cutting edge made of diamond that cuts the surface of the workpiece held by the chuck table with a tool, a tool wheel with the tool on the lower surface, and the tool. Using a tool cutting device including a tool cutting unit that rotatably supports the wheel and a cutting liquid supply device that supplies the cutting liquid to the tool.
A method for processing a workpiece, which includes a wafer, a device formed on the surface of the wafer, a bump on the device, the device, and a sealing material on the bump, and bites the workpiece. There,
A holding step of holding the workpiece on the chuck table, and
A tool cutting step of cutting the encapsulant with a tool to expose the bumps from the encapsulant is provided.
The tool cutting step is a method for processing a workpiece, which is carried out in a state where the temperature of the environment in which the tool cutting device is installed is −5 ° C. to + 10 ° C.

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