TWI789480B - Wafer Evaluation Method - Google Patents

Abstract

Provided are a wafer evaluation apparatus capable of evaluating the state of a ground surface of a wafer with a simple configuration, and a wafer evaluation method.

The evaluation device of this embodiment is equipped with: a rotary table for holding a wafer; a fine grinding unit for grinding the wafer; a measuring needle for contacting the back surface of the wafer ground by the fine grinding unit; and a moving unit for The measuring needle is held in a movable manner; and the storage unit stores, as the roughness information of the back surface, a sound generated when the measuring needle is moved relative to the back surface in a state where the measuring needle is brought into contact with the back surface.

Description

Wafer Evaluation Method field of invention

The present invention relates to a wafer evaluation device and a wafer evaluation method for evaluating the state of a ground surface of a wafer.

Background of the invention

In general, various wafers such as semiconductor wafers made of silicon, etc., on which semiconductor elements are formed on the front surface, or optical element wafers made of sapphire, SiC (silicon carbide), etc., on which optical elements are formed, are processed by grinding. A sharpening stone is used to sharpen the back side. As a processing device for processing such a wafer, there is known a device that has a plurality of holding tables that hold wafers respectively, a turntable that is equipped with a plurality of holding tables, and that is sequentially positioned by the rotation of the turntable. A grinding unit for rough grinding and a grinding unit for fine grinding held on the top of the workbench, and 1 wafer is processed continuously in the order of rough grinding and fine grinding (for example, refer to Patent Document 1). In such a processing apparatus, after finish grinding, the state (roughness) of the ground surface of the wafer may be checked in order to evaluate the quality of the wafer.

The status of the ground surface of the wafer is confirmed by taking out the wafer from the processing equipment and using a dedicated roughness tester. As such a roughness measuring device, the following measuring device has been proposed: a parallel link mechanism configured to move freely in the vertical direction, and the movable parallel link mechanism A stylus is installed on the lower side of the side, and a mirror is installed on the upper side of the movable side, and the displacement of the mirror is detected by a laser interferometer (for example, refer to Patent Document 2).

prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2009-158536

Patent Document 2: Japanese Patent Laid-Open No. 2000-018935

Summary of the invention

In the above-mentioned roughness detector, although the state of the ground surface of the wafer can be precisely measured, on the other hand, it is necessary to move the ground wafer to the roughness detector separately arranged from the processing device. , so the work process will become complicated. For this reason, there has been a demand for evaluating the state of the ground surface of a wafer with a simple configuration without using a dedicated roughness measuring device.

The present invention was made in view of the above, and an object of the present invention is to provide a wafer evaluation device and a wafer evaluation method capable of evaluating the state of a ground surface of a wafer with a simple configuration.

In order to solve the above-mentioned problems and achieve the purpose, the wafer evaluation device of the present invention includes: a holding unit for holding the wafer; a grinding unit for grinding the wafer; and a measuring needle for contacting the wafer ground by the grinding unit. round a grinding surface; a moving unit for movably holding the measuring needle; and a storage unit for causing the measuring needle to move relative to the grinding surface in a state in which the measuring needle is brought into contact with the grinding surface. The sound is stored as the roughness information of the grinding surface.

According to this configuration, since there is a storage unit that stores the sound generated when the measuring needle and the grinding surface are moved relatively as the roughness information of the grinding surface, it is possible to use the stored roughness of each grinding surface Evaluate the state of the grinding surface with a simple structure based on changes in information.

Also, the present invention is a wafer evaluation method for evaluating the state of the grinding surface of the wafer, and includes: a grinding step of grinding the wafer; a moving step of making the measuring needle contact the grinding surface of the wafer The measurement needle and the wafer are moved relative to each other under the condition of the moving step; the storing step is to store the sound generated during the moving step as the roughness information of the grinding surface.

According to this configuration, since there is a storage step of storing the sound generated when the measuring needle and the grinding surface are moved relatively as the roughness information of the grinding surface, it is possible to use the stored roughness of each grinding surface Evaluate the state of the grinding surface with a simple structure based on changes in information.

In this configuration, the moving step and the storing step are performed on a plurality of wafers that are continuously ground under arbitrary processing conditions by the processing device, and the monitoring step may be further provided. The aforementioned monitoring step The state of the grinding surface of the wafer is monitored from changes in the plural pieces of roughness information. According to this configuration, since the roughness information of the grinding surface of each wafer after continuous grinding is stored separately, the state of the grinding surface can be easily confirmed from the change of the stored roughness information of each grinding surface changes, so Abnormalities of processing equipment and abnormalities of wafers can be monitored.

According to the present invention, since the sound generated when the measuring needle and the grinding surface are moved relatively is stored as the roughness information of the grinding surface, it is possible to use the change of the stored roughness information of each grinding surface , and evaluate the state of the ground surface with a simple structure.

1: Evaluation device

2: Device housing

4: Vertical support plate

6, 8: Guide track

10: Rough grinding unit

12: Fine grinding unit

14, 32: Unit housing

16, 34: wheel seat

18, 36: Grinding wheel

18a, 36a: millstone abutment

18b, 36b: grinding stone

20, 38: electric motor

22, 40: mobile base station

24, 42: guided track

26, 44: Grinding feed mechanism

28, 46: ball screw

30, 48: Pulse motor

50: turntable

51, 53, 101, 215: Arrows

52: Work clamping table

54: Abutment

56: Adsorption chuck

58: The first cassette

60: The second cassette

62: Temporary workbench

68: Status evaluation unit

70:Wafer Handling Assembly

72: Holding Arm

74: Multi-section linkage mechanism

76:Wafer loading module

78:Wafer unloading module

80: Cover body

80A: Open and close the door

90: Control device

91: Computational Processing Department

92: Acquisition of sound waveform

93: storage unit (storage component)

94: Evaluation Department

95: Microphone

100: Rotary table (holding components)

100A: axis

110: Detection component

111: Ontology

112: Rod

112A: front end

113: Measuring needle

120: Mobile components

121: cage seat

122: carrier

125: washing water nozzle

200: Wafer

201: back (grinding surface)

202: front

203: Divide scheduled line

204: components

205: Protective Tape

210, 211, 212, 213, 216, 217, 218: track (moving track)

214: scars

A: Wafer loading and unloading area

B: Rough grinding area

C: Fine grinding processing area

df: difference

DA ₁ : roughness information of the first wafer

DA ₂ : roughness information of the 2nd wafer

DA _n : Roughness information of the nth wafer

DA ₁₁ , DA ₁₂ , DA ₁₃ : roughness information

FIG. 1 is a perspective view of a wafer as an evaluation object of the wafer evaluation apparatus of the present embodiment.

Fig. 2 is a perspective view of a configuration example of an evaluation device according to the present embodiment.

Fig. 3 is a perspective view showing an internal configuration of a state evaluation unit.

FIG. 4 is a functional configuration diagram of a state evaluation unit.

FIG. 5 is a flowchart showing the procedure of the wafer evaluation method according to the present embodiment.

Fig. 6 is a plan view showing an example of the movement locus of the measuring needle in the moving step.

FIG. 7 is a graph displaying the roughness information of a plurality of wafers acquired through the movement traces of FIG. 6 .

Fig. 8 is a plan view showing another example of the moving track of the measuring needle in the moving step.

FIG. 9 is a graph showing arranging and displaying a plurality of pieces of roughness information of one wafer acquired through the movement trace in FIG. 8 .

Fig. 10 is a plan view showing another example of the movement track of the measuring needle in the moving step.

form for carrying out the invention

The mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the constituent elements described below include those that can be easily imagined by those skilled in the art or those that are substantially the same. In addition, the configurations described below can be appropriately combined. In addition, omissions, substitutions, or changes of various configurations can be made without departing from the gist of the present invention.

About this embodiment, it demonstrates based on drawing. FIG. 1 is a perspective view of a wafer as an evaluation object of the wafer evaluation apparatus of the present embodiment. Fig. 2 is a perspective view of a configuration example of an evaluation device according to the present embodiment. The wafer evaluation apparatus of this embodiment is an apparatus that grinds the back surface 201 of the wafer 200 shown in FIG. 1 and evaluates the grinding state (roughness) of the ground back surface (ground surface) 201 after grinding. The wafer 200 is, for example, a disc-shaped semiconductor wafer with silicon as a base material, or an optical element wafer with sapphire, SiC (silicon carbide) or the like as a base material. As shown in FIG. 1 , the wafer 200 has elements 204 formed in a plurality of regions defined by grid-like dividing lines 203 formed on the front surface 202 . As shown in FIG. 2 , the back side 201 of the wafer 200 is ground by the evaluation apparatus 1 in a state where the protective tape 205 is attached to the front side 202 . The protective tape 205 is formed in a disk shape having the same size as the wafer 200, and is made of a flexible synthetic resin.

The evaluation device (processing device) 1 has a substantially cuboid-shaped device case 2, and a vertical support plate is provided on one end side of the device case 2 4. Two pairs of guide rails 6 and 8 extending in the vertical direction are provided on the inner surface of the vertical support plate 4 . On the guide track 6 on one side, the rough grinding unit 10 is installed in a manner that can move up and down, and on the guide track 8 on the other side, the fine grinding unit (grinding assembly) 12 can be placed on the Installed in a way to move up and down.

The rough grinding unit 10 is composed of a unit housing 14, a grinding wheel 18, an electric motor 20, and a mobile base 22. The aforementioned grinding wheel 18 is installed on the wheel base 16, and the aforementioned wheel base 16 is rotatable. Installed at the lower end of the aforementioned unit case 14 , the aforementioned electric motor 20 rotates the wheel seat 16 installed at the lower end of the unit case 14 in a counterclockwise direction, and the aforementioned mobile base 22 is equipped with the unit case 14 .

The grinding wheel 18 is constituted by an annular grindstone base 18a and a grinding grindstone 18b for rough grinding attached to the lower surface of the grindstone base 18a. A pair of guided rails 24 are formed on the mobile base 22. By fitting these guided rails 24 movably to the guide rails 6 provided on the vertical support plate 4, the rough grinding unit 10 can be Supported in a way that moves up and down.

The grinding feed mechanism 26 which moves the movable base 22 of the rough grinding unit 10 along this guide rail 6, and grinds and feeds the grinding wheel 18 is provided on the guide rail 6. As shown in FIG. The grinding feed mechanism 26 is composed of a ball screw 28, a pulse motor 30, and a nut not shown in the figure. The ball screw 28 is arranged on the vertical support plate 4 in parallel with the guide rail 6 in the vertical direction and is rotatably supported. For support, the aforementioned pulse motor 30 rotates and drives the ball screw 28 , and the aforementioned nut is mounted on the mobile base 22 and screwed to the ball screw 28 . by pulse The motor 30 is used to drive the ball screw 28 forward or reverse to move the rough grinding unit 10 in the up and down direction.

The fine grinding unit 12 is constituted in the same way as the rough grinding unit 10, and is composed of a unit housing 32, a grinding wheel 36, an electric motor 38, and a moving base 40. The aforementioned grinding wheel 36 is mounted on the wheel. seat 34, and the aforementioned wheel seat 34 is rotatably installed on the lower end of the unit case 32, the aforementioned electric motor 38 drives the wheel seat 34 installed on the upper end of the unit case 32 in the counterclockwise direction, and the aforementioned mobile base The table 40 is equipped with the unit case 32 . The grinding wheel 36 is composed of a ring-shaped grindstone base 36a and a grinding grindstone 36b for fine grinding installed on the lower surface of the grindstone base 36a.

A pair of guided rails 42 are formed on the mobile base 40. By movably fitting these guided rails 42 to the guide rails 8 provided on the vertical support plate 4, the fine grinding unit 12 can be moved It is supported by moving up and down.

A grinding feed mechanism 44 for grinding and feeding the grinding wheel 36 is provided on the guide rail 8 by moving the movable base 40 of the finish grinding unit 12 along the guide rail 8 . The grinding feed mechanism 44 is composed of a ball screw 46, a pulse motor 48, and a nut not shown in the figure. The ball screw 46 is arranged on the vertical support plate 4 parallel to the guide rail 8 in the vertical direction and is rotatably supported. , the aforementioned pulse motor 30 rotates and drives the ball screw 46 , and the aforementioned nut is mounted on the moving base 40 and screwed to the ball screw 46 . The fine grinding unit 12 is moved up and down by driving the ball screw 46 forwardly or reversely by the pulse motor 48 .

The evaluation device 1 is provided adjacent to the vertical support plate 4 and arranged The turntable 50 on the upper surface of the device housing 2. The turntable 50 is formed in a disc shape with a large diameter, and is rotated in the direction indicated by an arrow 51 by a rotation drive mechanism not shown in the figure. On the turntable 50, three work chucks 52 are arranged rotatably in a horizontal plane at a distance of 120 degrees from each other in the circumferential direction. The work holder 52 is composed of a disc-shaped base 54 and a disc-shaped adsorption chuck 56 formed of a porous ceramic material, and the suction unit that is not shown in the figure is actuated to hold the placed on the The wafer on the holding surface of the suction chuck 56 is sucked and held.

The work holder 52 is rotated in the direction indicated by the arrow 53 by a rotation drive mechanism not shown in the figure. The three work clamps 52 arranged on the turntable 50 are properly rotated by the turntable 50 to move in and out of the wafer area A, the rough grinding area B, the fine grinding area C, and the wafer in and out area. A to move in sequence.

The evaluation device 1 is provided with: a first cassette 58 arranged on one side of the wafer loading and unloading area A for storing the wafer 200 before grinding with a protective tape 205 attached to the front surface 202; The round loading and unloading area A is arranged on the other side, and is used for storing the second cassette 60 of the wafer 200 after the backside (grinding surface) 201 has been ground.

Between the first cassette 58 and the wafer loading and unloading area A, a temporary table 62 on which the wafer 200 unloaded from the first cassette 58 is placed is arranged. A state evaluation unit 68 for evaluating the state of the back surface 201 of the wafer 200 after grinding is provided between the wafer loading/unloading area A and the second cassette 60 .

The wafer transfer assembly 70 is composed of a holding arm 72 and a multi-joint link mechanism 74 that moves the holding arm 72, and can be accommodated in the first sheet The wafer 200 in the cassette 58 is carried out to the temporary stage 62 , and the wafer 200 measured by the state evaluation unit 68 is carried to the second cassette 60 .

The wafer loading unit 76 transports the pre-grinding wafer 200 placed on the temporary table 62 to the work chuck 52 positioned in the wafer loading and unloading area A. The wafer unloading unit 78 transports the ground wafer 200 placed on the chuck table 52 positioned in the wafer loading and unloading area A to the state evaluation unit 68 . Furthermore, the evaluation device 1 is provided with a control device 90 for controlling the operation of each component. The control device 90 controls the above-mentioned components of the evaluation device 1, namely: the rough grinding unit 10, the fine grinding unit 12, the three work clamps 52 arranged on the turntable 50, the wafer transfer unit 70, and the wafer transfer unit 70. The load-in module 76, the wafer unload module 78, the state evaluation unit 68, and the like make the evaluation device 1 perform grinding of the wafer 200 and evaluation of the ground back surface 201.

Next, the state evaluation unit 68 will be described. Fig. 3 is a perspective view showing an internal configuration of a state evaluation unit. FIG. 4 is a functional configuration diagram of a state evaluation unit. As shown in FIG. 2 , the state evaluation unit 68 includes a cover body 80 covering the outside, and a switch door 80A for carrying in or carrying out is provided on the cover body 80 . The cover body 80 is formed of a sound-insulating material to reduce the influence of noise inside the cover body 80 and outside the cover body 80 .

The state evaluation unit 68 includes: a rotary table (holding unit) 100 holding the ground wafer 200 as shown in FIG. The back side (grinding surface) 201 of the wafer 200 of 100 is used to detect the detection unit 110 of the state (roughness) of the back side 201, and the moving unit movably holding the detection unit 110 120. The rotary table 100 is provided with a disk-shaped suction chuck formed of porous ceramics at the center of the front (upper surface), and the suction chuck is connected to a suction unit not shown in the figure. Thereby, the rotary table 100 holds the wafer 200 by attracting the wafer 200 placed on the suction chuck. Further, the rotary table 100 is configured to be rotatable in the direction of the arrow 101 around an axis 100A ( FIG. 4 ) perpendicular to the above-mentioned front (upper surface).

The detection unit 110 includes a rod 112 extending substantially horizontally from the main body 111 , and a measurement needle 113 provided on a front end 112A of the rod 112 and extending vertically downward from the front end 112A. The lever 112 is configured to be swingable up and down centering on the base end part accommodated in the main body 111 . Therefore, the rod 112 swings up and down according to the shape of the back surface (grinding surface) 201 of the wafer 200 that is in contact with the measurement needle 113 . The measurement needle 113 generates a sound by moving the detection unit 110 and the rotary table 100 relative to each other in a state of being in contact with the back surface 201 of the wafer 200 . The measuring needle 113 is made of a material such as diamond or sapphire, and has a tip radius of, for example, 10 [μm] or less. Also, the needle tip is preferably formed into a spherical shape or a conical shape. In the present embodiment, for example, by rotating the rotary table 100 , a sound is generated when the measuring pin 113 relatively moves on the back surface 201 of the wafer 200 . And, the state (roughness) of the back surface 201 of the wafer 200 is evaluated in accordance with the relative change or difference of the sound generated by each wafer 200 .

The moving assembly 120 is arranged around the rotary table 100, and holds the detection assembly 110 and moves the detection needle 113 of the detection assembly 110 to the contact position on the rotary table 100, and from the rotary table 100 retreat position. The moving assembly 120 is equipped with: a cylindrical holder seat 121 erected on the upper surface of the device housing 2, and a platform 122 integrally formed on the side edge of the holder seat 121 in the horizontal direction, and can be loaded here. The body 111 of the detection component 110 is held on the stage 122 . When the holder seat 121 rotates around the axis of the cylinder, the detection unit 110 will move to the contact position on the rotary table 100 and the withdrawn position from the rotary table 100 . In addition, in this configuration, the measurement needle 113 can be positioned between the center side and the outer edge of the wafer 200 held on the rotary table 100 by rotating the holder base 121 . Therefore, even by rotating the holder seat 121 of the moving component 120 , the detection component 110 and the rotary table 100 can still be moved relatively.

In addition, in the present embodiment, a cleaning water nozzle 125 for supplying cleaning water to the wafer 200 transferred to the rotary table 100 after grinding is provided around the rotary table 100 . The washing water nozzle 125 is configured to be movable between an operating position where the nozzle opening is above the center of the rotary table 100 and a retracted position retracted from the rotary table 100 . Furthermore, the washing water nozzle 125 is connected to a washing water (for example, pure water) supply source which is not shown in the figure. Thereby, the back surface 201 of the ground wafer 200 transferred to the rotary table 100 can be cleaned by the supplied cleaning water. Therefore, in this embodiment, the measurement of the state (roughness) of the back surface 201 of the wafer 200 can be performed in a state in which the back surface 201 has been cleaned.

As shown in FIG. 4 , the control device 90 includes an arithmetic processing unit 91 , a sound waveform acquisition unit 92 , a storage unit (storage unit) 93 , an evaluation unit 94 , and an input/output interface device not shown. The arithmetic processing unit 91 has such The microprocessor (microprocessor) of the CPU (central processing unit), and executes the computer program stored in the ROM to generate a control signal for controlling the evaluation device 1, and the generated control signal will be output to the I/O interface device Each component of the evaluation device 1 is described. A microphone 95 having a sound collecting function is connected to the sound waveform acquisition unit 92 . The sound waveform acquisition unit 92 collects the generated sound (sound) by moving the measurement needle 113 relative to the wafer 200 through the microphone 95 to obtain the sound waveform. In the present embodiment, although the sound waveform acquisition unit 92 is configured to obtain the waveform of the generated sound (sound) through the microphone 95, it is not limited thereto. The vibration of the measurement needle 113 generated when the wafer 200 moves relatively is used as the waveform of the generated sound (sound).

The storage unit 93 stores the sound waveform information acquired by the sound waveform acquisition unit 92 as the roughness information of the ground back surface 201 . This roughness information is stored in association with the track (trajectory of movement) of the measurement pin 113 that moves in contact with the back surface 201 of the wafer 200 . For one wafer 200, one or a plurality of pieces of roughness information can be stored by moving the measurement needle 113 along one or a plurality of trajectories.

The evaluation unit 94 evaluates a wafer 200 by comparing the sound waveform information (roughness information) of one wafer 200 stored in the storage unit 93 with the sound waveform information (roughness information) of other wafers 200 . The state of the backside 201 of the wafer 200 . For example, for wafers 200 that have been continuously ground, the sound waveform information of each wafer 200 is stored, and changes in the stored sound waveform information (roughness information) of each wafer 200 are monitored. Then, The evaluation unit 94 evaluates that the grinding state of the back surface 201 has changed (deteriorated) when the difference (for example, the maximum value) of the change in the sound waveform information (roughness information) of each wafer 200 exceeds a threshold value and becomes larger. At this time, the sound waveform information (roughness information) of each wafer 200 is information formed by sound generated when the measuring needle 113 moves on the predetermined trajectory of the back surface 201 . Also, for example, the reference sound waveform information (reference roughness information) can be set for a normally ground wafer 200 first, and then the stored sound waveform information and reference sound of a wafer 200 can be monitored. The difference of the waveform information is used to evaluate the quality of the grinding state of the back surface 201 .

Next, a method for evaluating the rear surface (ground surface) 201 of the wafer will be described. FIG. 5 is a flowchart showing the procedure of the wafer evaluation method according to the present embodiment. Fig. 6 is a plan view showing an example of the movement locus of the measuring needle in the moving step. FIG. 7 is a graph showing the arrangement of roughness information of a plurality of wafers acquired through the movement trace of FIG. 6 .

First, the wafer 200 is held on the chuck 52 (step S1: holding step). The wafer 200 is transferred to the work chuck 52 positioned in the wafer loading and unloading area A by the wafer loading and unloading unit 76 , and is held by the chucking table 52 . At this time, the wafer 200 is held on the work chuck 52 with the protective tape 205 attached to the front 202 side and the back 201 side facing upward.

Next, rough grinding is performed on the wafer 200 held by the chuck 52 (step S2: rough grinding step). The wafer 200 held on the chuck table 52 is moved to the rough grinding processing area B by rotating the turntable 50 by 120 degrees. In this rough grinding processing area B, the grinding wheel 18 of the rough grinding unit 10 is rotated and lowered while the work chuck 52 is rotated, and further Rough grinding is performed until the grinding stone 18b of the rotating grinding wheel 18 comes into contact with the back surface 201 of the wafer 200 to thin the wafer to a predetermined thickness.

When the rough grinding step is finished, finish grinding is performed on the wafer 200 held on the work chuck 52 (step S3: finish grinding step). This finish grinding step corresponds to the grinding step in the present invention. In addition, the fine grinding step can also be set as a grinding step including the above-mentioned rough grinding step. After the rough grinding step is finished, the table 52 holding the wafer 200 that has undergone rough grinding is moved to the finish grinding processing area C by further rotating the turntable 50 by 120 degrees. In this finish grinding area C, the grinding wheel 36 of the finish grinding unit 12 is rotated and lowered while the work chuck 52 is rotated, and the grinding wheel 36 is ground and ground by rotating the grinding wheel 36 . Finish grinding in which the stone 36b contacts the back surface 201 of the wafer 200 and thins it to a predetermined thickness. In this configuration, the wafer 200 held by each chuck 52 is continuously ground by rotating the turntable 50 .

Next, the back surface 201 of the wafer 200 that has undergone finish grinding is cleaned (step S4: cleaning step). Specifically, the wafer 200 held on the chuck table 52 is moved to the wafer loading and unloading area A again by rotating the turntable 50 by 120 degrees. In addition, the ground wafer 200 positioned in the wafer loading and unloading area A is transported to the state evaluation unit 68 by the wafer loading and unloading unit 78 . In the state evaluation unit 68 , as shown in FIG. 3 , the wafer 200 is sucked and held on the rotary table with the back surface 201 facing upward. Then, the rotary table 100 is rotated in the direction of the arrow 101, the nozzle opening of the washing water nozzle 125 is positioned above the center of the rotary table 100, and washing water (for example, pure water) is supplied from the nozzle opening. borrow In this way, the ground wafer 200 transferred to the rotary table 100 can be cleaned from the back surface 201 side by the supplied cleaning water. Therefore, grinding dust that has adhered to the back surface 201 can be removed.

Next, in a state where the measuring pins 113 are brought into contact with the back surface 201 of the wafer 200, the measuring pins 113 and the wafer 200 are relatively moved (step S5: moving step). Specifically, as shown in FIG. 6 , the holder base 121 of the moving unit 120 is rotated to position the measurement needle 113 at a predetermined position on the wafer 200 (rotary table 100 ) determined in advance. Then, the rotary table 100 is rotated in the direction of the arrow 101 in a state where the measuring needles 113 are brought into contact with the back surface 201 of the wafer 200 .

Thereby, the measurement needle 113 moves along the predetermined trajectory 210 on the back surface 201 of the wafer 200 . At this time, the measurement needle 113 vibrates due to the fine unevenness of the grinding mark applied to the back surface 201 of the wafer 200 , and generates sound (sound) accompanying the vibration. After repeated experiments, the inventor obtained the following knowledge: the number of rotations of the rotary table 100 is the same as that of a record player for music (33 [rpm], 45 [rpm]), which is higher than the number of rotations of a record player for music. In the case of a lower rotation speed (10 [rpm]) or the rotation speed (40 [rpm]) when the rotary table 100 is idling, in either case, the measurement needle 113 vibrates and a sound is generated. Therefore, the rotation speed of the rotary table 100 is preferably about 10 [rpm] to 45 [rpm] including at least the rotation speed of the record player for music.

Next, the generated sound is stored in the storage unit 93 as roughness information of the back surface (grinding surface) 201 of the wafer 200 (step S6: storage step). Specifically, the sound waveform acquisition unit 92 uses the microphone 95 The sound (sound) generated between the measuring needle 113 and the back surface 201 of the wafer 200 is collected to obtain the sound waveform information. The storage unit 93 stores the sound waveform information acquired by the sound waveform acquisition unit 92 as the roughness information of the ground back surface 201 . This roughness information is stored in association with, for example, the trajectory 210 of the measurement needle 113 that moves in contact with the back surface 201 of the wafer 200, and in this embodiment, it is for a plurality of wafers 200 that are processed continuously. Each piece of roughness information (sound waveform information) is stored in association with the locus 210 .

Next, the state of the back surface 201 of the wafer 200 is monitored from changes in the plurality of pieces of roughness information (step S7: monitoring step). In this configuration, since the back surfaces 201 of the plurality of wafers 200 are continuously ground, the grinding state of the back surfaces 201 after finish grinding is usually substantially uniform. However, for example, during grinding, if the grinding conditions have been changed to the following situation, the grinding state of the ground back surface 201 will be greatly different: In the case of foreign matter such as tape scraps or contaminants, in the case of a wafer of a different type (material or surface processing) mixed in the wafer 200 being continuously processed, in the case of grinding the side of the protective tape 205, in the case of the wafer 200 The case where the back surface 201 is scratched, or the case where the grinding defect occurs due to a defect of the grinding stone. Therefore, the evaluation unit 94 will monitor whether the state of the back surface 201 of the wafer 200 changes from the changes in the plurality of roughness information, and based on whether the difference (for example, the maximum value) of the changes in the plurality of roughness information is greater than a predetermined threshold value It is good to evaluate the state of the back 201.

Specifically, as shown in FIG. 7 , the evaluation unit 94 reads out the roughness information DA ₁ of the first wafer 200 , the roughness information DA ₂ of the second wafer 200 , ... the n-th The roughness information DA _n of one wafer 200 is used as the roughness information of the backsides 201 of a plurality of wafers 200 that have been continuously ground. In addition, the evaluation unit 94 determines, for example, the maximum value of the amplitude (sound pressure) of the roughness information of the nearest wafer 200 (roughness information _DAn of the n-th wafer 200 in FIG. Whether the difference df of the maximum value of the amplitude of the roughness information of the wafer 200 is greater than a predetermined threshold value set in advance. At this time, as long as the difference df is greater than the threshold value, the roughness information of the next (n+1th) wafer 200 will be monitored, and if the difference df is greater than the threshold value, it will be evaluated as poor grinding, and the report will be made, for example. purpose.

In the present embodiment, for a plurality of wafers 200 which are continuously ground, the roughness information of the back surface 201 of the wafer 200 is acquired along one track 210 respectively, and the wafers 200 The change in the state of the back surface 201 of the wafer 200 is evaluated by changing the roughness information of the wafer 200, but the present invention is not limited thereto. For example, the state of the back surface 201 of one wafer 200 can also be evaluated by changing the movement locus of the measurement needle 113 . Fig. 8 is a plan view showing another example of the moving track of the measuring needle in the moving step. FIG. 9 is a graph showing arranging and displaying a plurality of pieces of roughness information of one wafer acquired through the movement trace in FIG. 8 . In this form, although as shown in FIG. 8 , the rotary table 100 is rotated in the direction of the arrow 101 in the state where the measuring needle 113 is in contact to form the moving track of the measuring needle 113, but it will be rotated every time it goes around. Change the position of the measuring needle 113 in the radial direction of the wafer 200, and move the measuring needle 113 along the three tracks 211, 212, 213 respectively. 113 moves relatively. The number of these tracks is not limited to three, as long as there are two or more. In addition, the measurement needle 113 may be moved along one trajectory formed in a spiral shape.

In this configuration, as shown in FIG. 9 , three pieces of roughness information DA ₁₁ , DA corresponding to three tracks 211 , 212 , and 213 can be acquired for one wafer 200 from the outside to the inside of the wafer 200 . _12. DA ₁₃ . Each of these roughness information items DA ₁₁ , DA ₁₂ , and DA ₁₃ has a portion that vibrates periodically with a large amplitude as a common feature. Therefore, it is possible to evaluate whether there is a flaw 214 formed across the three tracks 211, _{212 , 213 ,} for example, as shown in FIG. .

In addition, in the present embodiment, although the measuring needle 113 and the wafer 200 are relatively moved by rotating the rotary table 100, it is not limited to this, and for example, as shown in FIG. A moving mechanism (not shown) that linearly moves the table 100 in a predetermined direction (arrow 215 direction) relatively moves the measurement needle 113 along a plurality of trajectories 216 , 217 , and 218 .

As mentioned above, the evaluation device 1 of this embodiment is equipped with: the rotary table 100 holding the wafer 200; the fine grinding unit 12 for grinding the wafer 200; The back surface 201 of the chipped wafer 200; the moving assembly 120 is capable of movably holding the measurement needle 113; and the storage unit 93, in the state where the measurement needle 113 is in contact with the back surface 201, will make the measurement needle 113 and the back surface 201 face each other. The sound produced when moving is stored as the roughness information of the back surface 201, so it can be Changes in the roughness information of each back surface 201 of the wafer 200 can be used to evaluate the grinding state of the back surface 201 with a simple configuration, and it is possible to monitor abnormalities of the evaluation apparatus 1 performing grinding processing or abnormalities of the wafer 200 .

In addition, this invention is not limited to the invention of the said embodiment. That is, various modifications and implementations are possible without departing from the gist of the present invention. In the present embodiment, although the moving unit 120 holding the measuring needle 113 is configured to be arranged around the rotary table 100 as a holding unit, for example, the above-mentioned work clamp table 52 functions as a holding unit, and The measuring needle 113 is provided around the work clamp table 52, and the sound generated when the measuring needle 113 is moved relative to the ground back surface 201 at a point in time when the grinding process is not performed is used as the roughness of the back surface 201. Degree information can also be stored in the storage unit 93.

2: Device housing

68: Status evaluation unit

90: Control device

91: Computational Processing Department

92: Acquisition of sound waveform

93: storage unit (storage component)

94: Evaluation Department

95: Microphone

100: Rotary table (holding components)

100A: axis

101: Arrow

110: Detection component

111: Ontology

112: Rod

112A: front end

113: Measuring needle

120: Mobile components

121: cage seat

122: carrier

200: Wafer

201: back (grinding surface)

202: front

205: Protective Tape

Claims (1)

A method for evaluating a wafer is to evaluate the state of a ground surface of a wafer. The method for evaluating a wafer is characterized in that: a grinding step is performed to grind the wafer; Under the state of the grinding surface of the wafer, the measurement needle is moved relative to the wafer; and the storage step stores the sound generated during the implementation of the moving step as the roughness information of the grinding surface, so as to The moving step and the storing step are carried out on a plurality of wafers which are continuously ground by the processing device under arbitrary processing conditions, and the aforementioned evaluation method further includes a monitoring step. Information changes to monitor the state of the grinding surface of the wafer.

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