TWI783054B - Grinding device - Google Patents

Abstract

[Problem] To provide a grinding device capable of reducing the possibility of breaking the workpiece or causing damage to the surface to be ground when measuring the surface roughness. [Solution] A grinding device comprising a work chuck for holding a workpiece, a grinding unit for grinding the workpiece held on the work chuck, and non-contact measurement of the workpiece obtained by the grinding unit. A non-contact surface roughness measuring unit for measuring the surface roughness of the ground surface of the workpiece after grinding, the non-contact surface roughness measuring unit includes a light emitting unit that irradiates light to the ground surface, and receives light from the ground surface. A light receiving unit for the light reflected by the ground surface, a memory unit storing the relationship between the amount of light received by the light receiving unit and the surface roughness of the ground surface, and the relationship between the relationship stored in the memory unit and the A calculation unit that calculates the surface roughness of the surface to be ground based on the amount of light received by the light receiving unit.

Description

Grinding device

field of invention The present invention relates to a grinding device used when grinding workpieces such as wafers.

Background of the invention In order to reduce the size and weight of device wafers incorporated in various electronic devices, etc., opportunities for wafer thinning processing prior to dicing into device wafers are increasing. For example, the wafer can be ground and thinned by holding the device-equipped front side of the wafer with a work chuck and pressing against the back side of the wafer with a rotating grindstone tool (see, for example, patent Literature 1).

However, the flexural strength of device wafers obtained by dividing a wafer thinned by grinding is closely related to the surface roughness of the ground surface (back surface) of the wafer. Therefore, after the wafer is ground, the surface roughness of the ground surface of the wafer is usually measured. In the measurement of the surface roughness, for example, a surface roughness measuring device provided with a stylus that comes into contact with the ground surface to be measured is used. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2000-288881

Summary of the invention The problem to be solved by the invention However, if the above-mentioned surface roughness measuring device is used, for example, the wafer may be accidentally dropped when transporting the wafer from the grinding device to the surface roughness measuring device, and the wafer may be damaged. In addition, there is a possibility that the surface to be ground of the wafer will be damaged by the stylus of the surface roughness measuring device, thereby lowering the flexural strength of the device wafer.

The present invention was made in view of the above-mentioned problems, and its object is to provide a grinding device that can reduce the possibility of damaging the workpiece or causing damage to the surface to be ground when measuring the surface roughness. suppressed lower. means to solve problems

According to one aspect of the present invention, there is provided a grinding device including a work chuck holding the workpiece, a grinding unit for grinding the workpiece held on the work chuck, and A non-contact surface roughness measuring unit for measuring the surface roughness of the ground surface of the workpiece ground by the grinding unit in a non-contact manner, the non-contact surface roughness measuring unit including the a light emitting unit that emits light on the beveled surface, a light receiving unit that receives light reflected on the ground surface, a memory unit that memorizes the relationship between the amount of light received by the light receiving unit and the surface roughness of the ground surface, and a calculating unit that calculates the surface roughness of the surface to be ground from the relationship stored in the memory unit and the amount of light received by the light receiving unit. Invention effect

A grinding device according to one aspect of the present invention is equipped with a non-contact surface roughness measuring unit, and the non-contact surface roughness measuring unit includes a light emitting unit that irradiates light to the ground surface of the workpiece, The light-receiving part of the light reflected on the beveled surface, the memory part that stores the relationship between the light-receiving part and the surface roughness of the ground surface, and the calculation from the relationship memorized in the memory part and the light-receiving part The calculation unit of the surface roughness of the ground surface, and can measure the surface roughness in a non-contact manner according to the amount of light received by the light receiving part, so there is no possibility of damage to the ground surface due to the contact of the stylus situation.

Also, since the non-contact surface roughness measuring unit is installed in the grinding device, it is not necessary to transport the workpiece to a surface roughness measuring device separate from the grinding device in order to measure the surface roughness of the ground surface . That is, since the conveyance route of the workpiece is shortened or eliminated, the possibility of accidentally damaging the workpiece during this conveyance can be suppressed to a low level.

form for carrying out the invention An embodiment of one aspect of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a configuration example of a grinding device 2 according to this embodiment. As shown in FIG. 1 , the grinding machine 2 is provided with a base 4 that supports each component. At the rear end of the base 4, a wall-shaped support structure 6 is provided. An opening 4 a is formed on the front side of the upper surface of the base 4 , and a conveying unit 8 for conveying a plate-shaped workpiece 11 is arranged in the opening 4 a.

The workpiece 11 is, for example, a disk-shaped wafer formed of a material such as silicon (Si). However, the material, shape, structure, size, etc. of the workpiece 11 are not limited. For example, a substrate formed of other materials such as semiconductors, ceramics, resins, and metals may be used as the workpiece 11 . Moreover, the protection member 17 etc. may be attached to the surface of the object 11 opposite to the surface to be ground 11a (refer FIG. 2).

Cassettes 10a, 10b for accommodating a plurality of workpieces 11 are placed on the side area of the opening 4a. A centering mechanism 12 is provided behind the area where the cassette 10a is placed. The centering mechanism 12 adjusts the position of the center of the workpiece 11 conveyed from the cassette 10 a by the conveying unit 8 , for example.

At the rear of the centering mechanism 12, a carrying-in unit 14 for holding and rotating the workpiece 11 is provided. An opening 4 b is formed behind the carrying-in unit 14 . An X-axis moving table (not shown), an X-axis moving unit (not shown) for moving the X-axis moving table in the X-axis direction (front and rear direction) are arranged in the opening 4b, and a cover X-axis moving work The worktable cover 16 of the table, and the dust-proof and drop-proof cover 18 covering the X-axis moving unit.

The X-axis moving unit is equipped with a pair of X-axis guide rails (not shown) parallel to the X-axis direction, and an X-axis moving table is slidably installed on the X-axis guide rails. A nut portion (not shown) is provided on the lower surface side of the X-axis movable table, and an X-axis ball screw (not shown) parallel to the X-axis guide rail is screwed into the nut portion.

An X-axis pulse motor (not shown) is connected to one end of the X-axis ball screw. By using the X-axis pulse motor to rotate the X-axis ball screw, the X-axis moving table can move in the X-axis direction along the X-axis guide rail. A chuck 20 for attracting and holding the workpiece 11 is provided on the upper surface side of the X-axis movable table.

The work chuck 20 is connected to a rotational drive source such as a motor (not shown), and rotates around a rotational axis substantially parallel to the Z-axis direction (vertical direction). Furthermore, the work chuck 20 is moved between the loading and unloading area before loading and unloading the workpiece 11 and the grinding area behind grinding the workpiece 11 by the above-mentioned X-axis moving means.

The upper surface of the work chuck 20 is exposed to the outside of the table cover 16 , and a part of the upper surface serves as a holding surface for attracting and holding the workpiece 11 . The holding surface is connected to a suction source (not shown) through a suction path (not shown) formed inside the chuck table 20 or the like. The workpiece 11 carried into the work holder 20 by the carrying unit 14 is sucked and held on the work holder 20 by the negative pressure of the suction source acting on the holding surface.

The front surface of the supporting structure 6 is provided with a Z-axis moving unit 22 . The Z-axis moving unit 22 has a pair of Z-axis guide rails 24 parallel to the Z-axis direction, and a Z-axis moving plate 26 is slidably mounted on the Z-axis guide rails 24 . A nut portion (not shown) is provided on the rear surface side (back side) of the Z-axis moving plate 26 , and a Z-axis ball screw 28 parallel to the Z-axis guide rail 24 is screwed to the nut portion.

A Z-axis pulse motor 30 is connected to one end of the Z-axis ball screw 28 . The Z-axis ball screw 28 is rotated by the Z-axis pulse motor 30 , and the Z-axis moving plate 26 can move along the Z-axis guide rail 24 in the Z-axis direction.

On the front surface (front surface) of the Z-axis moving plate 26, a grinding unit 32 for grinding the workpiece 11 is provided. The grinding unit 32 includes a cylindrical spindle housing 34 fixed to the Z-axis moving plate 26 . Inside the spindle case 34 is accommodated a spindle 36 serving as a rotation axis substantially parallel to the Z-axis direction (vertical direction).

A disc-shaped mounting seat 38 is fixed to the front end portion (lower end portion) of the main shaft 36 exposed from the main shaft housing 34 . A grinding wheel 40 having substantially the same diameter as the mounting seat 38 is mounted on the lower surface of the mounting seat 38 . The grinding wheel 40 includes, for example, a wheel base formed of a metal material such as stainless steel or aluminum. A plurality of grinding stones are arranged on the lower surface of the wheel base, and the plurality of grinding stones are formed by dispersing abrasive grains such as diamond in a binder such as resin or metal.

A rotational drive source (not shown) such as a motor is connected to the base end side (upper end side) of the main shaft 36 . The grinding wheel 40 is rotated through the spindle 36 by the force transmitted from the rotating drive source. Inside or near the grinding unit 32, a nozzle (not shown) for supplying a grinding fluid such as pure water to the workpiece 11 and the like is provided.

At a position adjacent to the carrying-in unit 14, a carrying-out unit 42 for holding and rotating the workpiece 11 is provided. In front of the unloading unit 42 and behind the area where the cassette 10b is placed, a cleaning unit 44 for cleaning the ground workpiece 11 is arranged. The workpiece 11 cleaned by the cleaning unit 44 is transported by the transport unit 8 and accommodated, for example, in the cassette 10b. In front of the opening 4a, an operation panel 46 for inputting grinding conditions and the like is provided.

When the workpiece 11 is ground, for example, the workpiece 11 is carried into the work chuck 20 positioned in the loading and unloading area with the surface to be ground 11 a exposed above. Then, the workpiece 11 is sucked and held on the work holder 20, and the work holder 20 is moved to the grinding area. Thereafter, the chuck table 20 and the grinding wheel 40 are each rotated, and the grinding unit 32 is lowered while supplying grinding fluid to the ground surface 11 a of the workpiece 11 and the like.

Thereby, the workpiece 11 can be ground by bringing the grinding stone of the grinding wheel 40 into contact with the surface 11 a to be ground of the workpiece 11 . Furthermore, the lowering speed (lowering amount) of the grinding unit 32 is adjusted so that the lower surface of the grinding stone can be pressed against the ground surface 11 a side of the workpiece 11 with an appropriate force.

Above the loading and unloading area, a non-contact surface roughness measuring unit 48 for non-contact measuring the surface roughness of the ground surface 11 a of the workpiece 11 is provided. FIG. 2 is a diagram schematically showing a configuration example of the non-contact surface roughness measurement unit 48 . The non-contact surface roughness measuring unit 48 measures the surface roughness by utilizing the correlation existing between the surface roughness of the ground surface 11a and the reflection amount (intensity) of light reflected on the ground surface 11a. The unit, and includes a light emitting unit 50 and a light receiving unit 52 .

The light emitting unit 50 may be a light source such as an LED, and irradiates light to the ground surface 11a of the workpiece 11 positioned below. On the other hand, the light receiving part 52 may be a photodetector such as a light receiving element, and receives the light irradiated from the light emitting part 50 and reflected on the ground surface 11a to generate a voltage corresponding to the amount of light received (received light intensity). Waiting for the signal. Therefore, the wavelength of the light irradiated from the light emitting part 50 toward the surface to be ground 11a can be set within a range that can be reflected on the surface to be ground 11a.

However, the structure of the light emitting unit 50 or the light receiving unit 52 is not particularly limited. The light emitting unit 50 is configured, for example, to guide the light of the light source with an optical fiber or the like to radiate downward. Similarly, the light receiving unit 52 is configured, for example, to guide the received light to a photodetector through an optical fiber or the like. The intensity of the light irradiated from the light emitting part 50 to the surface 11a to be ground can be arbitrarily set.

In addition, in this embodiment, the positional relationship between the light emitting unit 50 and the workpiece 11 is adjusted so that the light from the light emitting unit 50 is irradiated on a circular area (irradiated area) with a diameter of about 0.1 mm. . Similarly, in the present embodiment, the positional relationship between the light receiving unit 52 and the workpiece 11 is adjusted so that the light reflected on the ground surface 11 a can be appropriately received by the light receiving unit 52 .

Thereby, it becomes possible to measure the surface roughness of the surface to be ground 11 a in a circular irradiated region having a diameter of about 0.1 mm. However, the shape, size, and the like of the irradiated area can be appropriately changed in accordance with the required measurement accuracy, measurement range, and the like. Furthermore, in this non-contact surface roughness measurement unit 48, it becomes possible to measure the average surface roughness of the irradiated area.

A processing unit 54 is connected to the light receiving unit 52 , and the processing unit 54 processes signals such as a voltage generated in the light receiving unit 52 . The processing unit 54 includes a memory unit 54a, which stores in advance the intensity I of the signal generated by the light receiving unit 52 (that is, the amount of light received by the light receiving unit 52) and the surface roughness R of the ground surface 11a. (eg arithmetic mean roughness).

FIG. 3 is a graph showing an example of the relationship stored in the memory unit 54a. This relationship is obtained by, for example, the following method: the intensity I is measured by receiving the light reflected on the ground surface 11a of the workpiece 11 at the light receiving part 52, and the ground surface is measured by a known method or the like. The surface roughness of the surface 11a. In addition, in FIG. 3, although the relationship between the surface roughness R and the intensity|strength I is shown in the graph of a curve, these relationships may also be shown in the graph of a line.

In addition, the processing unit 54 includes a calculation unit 54b, which calculates the received signal from the relationship stored in the memory unit 54a and the intensity I of the signal generated by the light receiving unit 52 (that is, the amount of light received by the light receiving unit 52). The surface roughness R of the grinding surface 11a. For example, as shown in FIG. 3 , when the light receiving unit 52 generates a signal with intensity _I1 , the calculation unit 54 b refers to the relationship stored in the memory unit 54 a to calculate the surface roughness R1 corresponding to the intensity _I1 .

When measuring the surface roughness R of the ground surface 11a of the workpiece 11 with the non-contact surface roughness measuring unit 48 configured in this way, for example, the work table 20 is moved to the loading and unloading area, and the surface roughness R is measured from above. The light emitting part 50 irradiates light to the surface to be ground 11a below. Then, the light reflected on the ground surface 11 a is received by the light receiving unit 52 . Thereby, a signal of the intensity I corresponding to the amount of received light can be generated in the light receiving unit 52 .

After that, the calculation unit 54b calculates the surface roughness R corresponding to the intensity I by referring to the relationship stored in the memory unit 54a. The calculated surface roughness R is used for quality control of the workpiece 11 and the like. Furthermore, the measurement of the surface roughness R may be performed while the workpiece 11 is stopped with respect to the non-contact surface roughness measurement unit 48, or the workpiece 11 may be measured with respect to the non-contact surface roughness measurement unit 48. Unit 48 is performed while moving.

As described above, since the grinding apparatus 2 of this embodiment includes the non-contact surface roughness measurement unit 48, and the non-contact surface roughness measurement unit 48 includes a light emitting unit that irradiates light to the ground surface 11a of the workpiece 11 50. Receive the light receiving part 52 of the light reflected on the ground surface 11a, and store the intensity I of the signal generated in the light receiving part 52 (that is, the amount of light received by the light receiving part 52) and the surface of the ground surface 11a. The storage unit 54a for the relationship between the roughnesses R, and the calculation unit 54b for calculating the surface roughness R of the ground surface 11a from the relationship stored in the storage unit 54a and the intensity I of the signal generated by the light receiving unit 52, In addition, the surface roughness R can be measured in a non-contact manner according to the amount of light received by the light receiving portion 52, so there is no possibility of damage to the ground surface 11a due to the contact of the stylus.

In addition, since the non-contact surface roughness measurement unit 48 is provided in the grinding device 2, it is not necessary to transport the workpiece 11 to be separated from the grinding device 2 in order to measure the surface roughness R of the ground surface 11a. The surface roughness measuring device. That is, since the conveyance route of the workpiece 11 is shortened or eliminated, the possibility of accidentally damaging the workpiece 11 during this conveyance can be suppressed to a low level.

In addition, this invention is not limited by description of the said embodiment, It can change variously and can implement. For example, the loading/unloading area and the area including the non-contact surface roughness measurement unit 48 are surrounded by a light shielding member to prevent incident light from the outside to the light receiving unit 52 . Thereby, the surface roughness R can be measured more accurately.

In addition, the structures, methods, etc. of the above-mentioned embodiments can be appropriately changed and implemented within the scope not departing from the purpose of the present invention.

10a, 10b‧‧‧cassette 11‧‧‧processed object 11a‧‧‧ground surface 12‧‧‧centering mechanism 14‧‧‧Moving into the unit 16‧‧‧Workbench Cover 17‧‧‧protective components 18‧‧‧Dust-proof and drip-proof cover 2‧‧‧Grinding device 20‧‧‧Work clamping table 22‧‧‧Z-axis moving unit 24‧‧‧Z-axis guide rail 26‧‧‧Z-axis moving plate 28‧‧‧Z-axis ball screw 30‧‧‧Z axis pulse motor 32‧‧‧Grinding unit 34‧‧‧Spindle housing 36‧‧‧Spindle 38‧‧‧Mounting seat 4‧‧‧Abutment 4a, 4b‧‧‧opening 40‧‧‧Grinding wheel 42‧‧‧Move out unit 44‧‧‧Cleaning unit 46‧‧‧operation panel 48‧‧‧Non-contact surface roughness measurement unit 50‧‧‧luminous part 52‧‧‧light receiving part 54‧‧‧Processing Department 54a‧‧‧memory 54b‧‧‧Computing Department 6‧‧‧Support structure 8‧‧‧Conveyor unit X, Y, Z‧‧‧direction

FIG. 1 is a perspective view schematically showing a configuration example of a grinding device. FIG. 2 is a diagram schematically showing a configuration example of a non-contact surface roughness measurement unit. Fig. 3 is a graph showing an example of the relationship stored in the memory unit.

11‧‧‧processed object

11a‧‧‧ground surface

20‧‧‧Work clamping table

48‧‧‧Non-contact surface roughness measurement unit

50‧‧‧luminous part

52‧‧‧light receiving part

54‧‧‧Processing Department

54a‧‧‧memory

54b‧‧‧Computing Department

Claims (1)

A grinding device, characterized in that: have: Work clamping table to hold the workpiece; a grinding unit for grinding the workpiece held on the work clamp; and a non-contact surface roughness measuring unit for measuring the surface roughness of the ground surface of the workpiece that has been ground by the grinding unit in a non-contact manner, The non-contact surface roughness measurement unit consists of: a light emitting part for irradiating light to the surface to be ground; a light receiving part, which receives the light reflected on the ground surface; a memory unit that memorizes the relationship between the amount of light received by the light receiving unit and the surface roughness of the ground surface; and The calculating unit calculates the surface roughness of the surface to be ground from the relationship stored in the memory unit and the amount of light received by the light receiving unit.

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