CN118595924A - Grinding device - Google Patents

Abstract

The invention provides a processing device which can simply measure the thickness and shape of the whole surface of a wafer without reducing the operation efficiency of grinding processing of the wafer, automatically detect when defective products are generated and prevent a large amount of product defects. The following structure is formed, wherein the measuring mechanism (16) comprises: a shape measurement mechanism (20), wherein the shape measurement mechanism (20) shifts a measurement position (P3) of the wafer (W) along the radial direction of the wafer (W) during or after the grinding processing of the wafer (W) to measure the thickness distribution of the wafer (W); a determination means (17A), wherein the determination means (17A) determines whether the shape of the wafer (W) is correct or not based on the thickness distribution of the wafer (W) measured by the shape measurement means (20); and a control unit (17B), wherein the control unit (17B) stops grinding the wafer (W) according to the determination result of the determination unit (17).

Description

Grinding device

Technical Field

The invention relates to a grinding device for grinding the back side of a wafer.

Background Art

In the field of semiconductor manufacturing, in order to form a semiconductor wafer such as a silicon wafer (hereinafter referred to as a "wafer") into a thin film, back grinding is performed to grind the back side of the wafer. Among the grinding devices that perform such back grinding, there are also known grinding devices that use a contact-type thickness measuring mechanism to measure the thickness of the wafer during the grinding process (for example, refer to Patent Document 1).

Patent Document 1 discloses a grinding device that measures the thickness of a wafer by a contact-type thickness measuring mechanism during rough grinding or finish grinding. The thickness measuring mechanism measures the thickness of the wafer at a plurality of concentric circles of different diameters around the center of the wafer.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2016-16457

Summary of the invention

Problems to be solved by the invention

However, in such a grinding device, since the thickness of the wafer is measured while performing rough grinding or finish grinding, for example, when measuring the center thickness of the wafer, the grinding wheel must be retracted upward, which increases the processing time and reduces the efficiency of the wafer grinding process.

In addition, in the grinding process of the wafer, it is necessary not only to measure the thickness of the wafer, but also to measure the shape distribution of the entire wafer. That is, there is also a process of measuring the shape of the wafer after grinding, and automatically controlling the shape of the wafer by providing feedback based on the result during the next processing. For this purpose, it is necessary to add a measuring device for thin film measurement for thickness control during the cutting process, and also prepare a measuring device for shape measurement. In such a case, in the past, a method was adopted in which a measuring device for thin film control was used for processing at the grinding position, and after completion, the wafer was transported to a measuring position where a measuring device for shape measurement was provided, and the shape was measured at the transported measuring position. In addition, based on the result, the next processing shape is fed back to perform shape control.

Therefore, in the past processing equipment, it is necessary to prepare two types of measuring devices, one for film thickness control during processing and the other for normal measurement. Therefore, there is a problem of high cost. In addition, after processing, there is a problem that the wafer needs to be transported from the grinding position to the shape measurement position, which increases the processing time and reduces the operating efficiency of the wafer grinding process.

Therefore, in order to provide a processing device that can simply measure the thickness and shape of the entire surface of the wafer without reducing the operating efficiency of the wafer grinding process, and automatically detect when defective products are produced, thereby preventing the large-scale occurrence of defective products, a technical problem that needs to be solved has arisen, and the purpose of the present invention is to solve this problem.

Technical solutions to solve problems

The present invention is proposed to achieve the above-mentioned purpose. The invention described in technical solution 1 provides a grinding device, which includes: a rotating table that can hold a wafer and realize rotation; a table conveying mechanism that moves the rotating table between a grinding position and a non-grinding position; a grinding mechanism that has a grinding wheel that grinds the upper surface of the wafer that moves to the grinding position; and a measuring mechanism that measures the thickness of the wafer that rotates together with the rotating table. The grinding device continuously grinds a plurality of workpieces. The measuring mechanism includes: a shape measuring mechanism that displaces the measuring position of the wafer along the radial direction of the wafer during movement from the grinding position to the non-grinding position to measure the thickness distribution of the wafer; a determination mechanism that determines whether the shape of the wafer is correct based on the thickness distribution of the wafer measured by the shape measuring mechanism; and a control unit that determines whether to continue or stop the grinding of the wafer based on the determination result of the determination mechanism.

According to this structure, the determination mechanism determines whether the wafer is correct or not based on the thickness distribution of the wafer obtained by the shape measuring mechanism. If there is no problem, the grinding process of the next wafer is directly continued. If there is a problem, the grinding process of the next wafer can be automatically stopped by the control unit. Therefore, when a problem occurs during the grinding process of the wafer, the problem is automatically stopped immediately and handled, so a large number of defective products can be prevented from being discharged. In addition, when determining, if the threshold value used as the determination criterion is changed, the determination criterion can be easily adjusted for each type of wafer, for example.

The invention described in Technical Solution 2 relates to the grinding device described in Technical Solution 1, and is characterized in that, with respect to the structure described in Technical Solution 1, the above-mentioned determination mechanism compares the thickness distributions of the plurality of wafers determined to be of correct shape, and determines whether there is an abnormal shape in a common portion in each thickness distribution, and the above-mentioned control unit stops grinding the above-mentioned wafer when the above-mentioned determination mechanism determines that there is an abnormal shape in a common portion in each thickness distribution.

According to this structure, by further comparing a wafer judged to be normal in the measurement of the wafer thickness distribution with multiple wafers measured before this wafer, it is determined whether there is an abnormal shape in the common part of each thickness distribution, thereby minimizing the generation of continuous defective products.

The invention described in claim 3 is directed to a grinding device, which relates to the structure described in claim 1, wherein the measurement position of the wafer by the shape measuring mechanism is located on an imaginary line of the center of the moving wafer.

According to this structure, when the turntable moves from the grinding position to the non-grinding position with the rotation of the wafer, the wafer is displaced approximately directly below the measurement position (measurement location) set on the imaginary line of the wafer center. Thus, the thickness distribution in the radial direction of the wafer, that is, the thickness of the entire wafer, can be measured by the shape measurement mechanism arranged at the measurement position.

The invention described in claim 4 is directed to a grinding device, which relates to the structure described in claim 3, wherein the table transport mechanism moves the rotating table in such a manner that the wafer center virtual line becomes a straight line.

According to this structure, at the measurement position on the way when the turntable moves linearly from the non-grinding position toward the grinding position, performs processing at the grinding position, and then moves linearly (displaces) from the grinding position toward the non-grinding position and returns, the thickness distribution in the radial direction of the wafer, that is, the thickness distribution of the entire wafer, can be measured.

The invention described in claim 5 is directed to a grinding device, which relates to the structure described in claim 3, wherein the table transport mechanism moves the rotating table in such a manner that the wafer center virtual line becomes a circle.

According to this structure, for example, a rotating indexing table is used, and the rotating table moves from a non-grinding position toward a grinding position, and the trajectory (imaginary line) of the center of the wafer describes a circle. In addition, after processing at the grinding position, the thickness distribution of the wafer can be measured at a measuring position set on the way back from the grinding position to the non-grinding position while describing a circle.

The invention described in Technical Solution 6 relates to a grinding device, which relates to the structure described in Technical Solution 5, wherein the movement of the above-mentioned rotating table moves sequentially through a rough grinding position for rough grinding the above-mentioned wafer, a fine grinding position for fine grinding the above-mentioned wafer, and a non-grinding position for loading and unloading the above-mentioned wafer.

According to this structure, the wafer held on the rotating table is rotated from the non-grinding position to the rough grinding position and the fine grinding position in sequence and then returns to the non-grinding position. In addition, the thickness distribution of the wafer can be measured at the measuring position set on the way back.

Effects of the Invention

According to the present invention, the determination mechanism determines whether the wafer is correct or not based on the thickness distribution of the wafer obtained by the shape measuring mechanism. If there is no problem, the grinding process of the next wafer is directly carried out. If there is a problem, the grinding process of the next wafer can be automatically stopped by the control unit. Therefore, when a problem occurs during the grinding process of the wafer, it can be stopped automatically immediately to prevent the discharge of a large number of defective products, thereby preventing the reduction of the yield rate, and shortening the processing time to seek to improve productivity. In addition, when determining, if the threshold value used as the determination criterion is changed, the determination criterion can be simply adjusted according to each type of wafer, for example, so it can be applied to grinding devices that process multiple types of wafers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a perspective view schematically showing a schematic structure of an example of a grinding device according to an embodiment of the present invention;

FIG. 2 is a diagram schematically showing the main structure of the grinding machine around the grinding processing unit, FIG. 2(a) is a plan view showing the structure around the stage conveying mechanism and the measuring mechanism, and FIG. 2(b) is a side view showing the structure of the measuring mechanism together with the rotating grinding wheel;

FIG3 is a schematic diagram for explaining the operation of the main structure of the grinding processing section of the grinding device, FIG3(a) is an explanatory diagram of a state in which the wafer is arranged at a non-grinding position together with the rotating table, FIG3(b) is an explanatory diagram of a state in which the wafer is moved from the non-grinding position to the grinding position for grinding processing, FIG3(c) is an explanatory diagram of a state just after the grinding processing is completed, FIG3(d) is an explanatory diagram of a linear state at the start of measurement of the thickness shape in the radial direction and the thickness distribution in the circumferential direction of the wafer after the grinding processing is completed, and FIG3(e) is an explanatory diagram after the measurement of the thickness shape in the radial direction and the thickness distribution in the circumferential direction of the wafer is just started;

FIG4 is a diagram showing an example of data obtained by shape measurement;

FIG5 is a diagram showing an example of converting the data of FIG4 into three-dimensional map data;

6 is a flow chart illustrating a procedure for determining the quality of processing based on data measured by a measuring mechanism;

7 is a block diagram showing a modified example of the control unit in the grinding device;

8 is a flow chart illustrating another procedure for determining the quality of processing based on data measured by the measuring mechanism;

FIG9 is a diagram for explaining a problem when dust exists between a turntable and a wafer, FIG9(a) is a diagram schematically showing dust exists between the turntable and the wafer, FIG9(b) is a diagram showing a state where a concave portion is formed on the surface of the wafer, and FIG9(c) is a diagram showing a state where a concave portion and a crack are formed on the surface of the wafer;

FIG. 10 is a plan view schematically showing an example of a grinding device that uses an indexing table to perform rotational motion.

DETAILED DESCRIPTION

In order to achieve the purpose of providing a grinding device that can simply measure the thickness and shape of the entire surface of a wafer without reducing the operating efficiency of the wafer grinding process, and automatically detect when a defective product is produced, thereby preventing a large number of defective products from occurring, the present invention is achieved by forming the following structure, which includes: a rotating table that can hold the wafer and rotate it; a table conveying mechanism that moves the above-mentioned rotating table between a grinding position and a non-grinding position; a grinding mechanism that has a grinding wheel that grinds the upper surface of the above-mentioned wafer that has moved to the above-mentioned grinding position; and a measuring mechanism. The grinding device continuously grinds a plurality of workpieces, wherein the measuring mechanism comprises: a shape measuring mechanism which displaces the measuring position of the wafer in the radial direction of the wafer to measure the thickness distribution of the wafer during movement from the grinding position to the non-grinding position; a determination mechanism which determines whether the shape of the wafer is correct based on the thickness distribution of the wafer measured by the shape measuring mechanism; and a control unit which determines whether to continue or stop the grinding of the wafer based on the determination result of the determination mechanism.

Example

An embodiment of the present invention is described in detail below with reference to the accompanying drawings. In addition, in the following embodiments, when the number, value, amount, range, etc. of the constituent elements are mentioned, except for the cases that are specifically stated and the cases that are obviously limited to a specific number in principle, they are not limited to the specific number and can be more than or less than the specific number.

Furthermore, when referring to the shapes and positional relationships of components, shapes similar to or approximate to the shapes are substantially included, except for cases where it is particularly noted or where it is obvious that such a shape is not the case in principle.

In addition, the drawings may be exaggerated to make the features easier to understand, such as by enlarging the feature parts, and the size ratios of the components may not be the same as the actual ones. In addition, in the cross-sectional views, the shadows of some components may be omitted to make the cross-sectional structure of the components easier to understand.

In addition, in the following description, the expression of the up and down or left and right directions is not absolute, and is appropriate when describing the posture of each part of the grinding device of the present invention, but when the posture changes, it should be interpreted in accordance with the change of the posture. In addition, in the description of the entire embodiment, the same reference numerals are used for the same elements.

Fig. 1 is a perspective view schematically showing the general structure of a grinding device 10 of the present invention. The grinding device 10 has, in a housing 11 covered by a dust and drip proof cover or the like, a rotating table 12 for holding and rotating a wafer W; a table conveying mechanism 13 for moving the rotating table 12 between a grinding position P1 and a non-grinding position P2; a grinding mechanism 15 having a rotating grinding wheel 14 for grinding the surface of the wafer W set at the grinding position P together with the rotating table 12; a measuring mechanism 16 for measuring the shape of the wafer W rotating together with the rotating table 12; a control unit 17 for controlling the overall operation of the grinding device 10, etc. In addition, taking the shuttle type as an example, the turntable 12 of the grinding device 10 of this embodiment operates in the following manner: the wafer W is held at the non-grinding position P2, and the wafer W is linearly transported to the grinding position P1 together with the turntable 12 by the action of the table conveying mechanism 13, and the wafer W is ground at the grinding position P1. By the same action of the table conveying mechanism 13, the wafer W that has completed the prescribed grinding at the grinding position P1 is linearly transported to the non-grinding position P2 and returned, and is replaced with a new wafer W at the non-grinding position P2 and transported to the grinding position P1 again.

The grinding mechanism 15 is a structure that grinds the surface of the wafer W on the turntable 12 that moves from the non-grinding position P2 to the grinding position P1 along with the wafer W. Before the turntable 12 moves to the grinding position P1, the grinding mechanism 15 moves to an upper position that does not hinder the movement of the turntable 12 and the like, and when the movement of the turntable 12 to the grinding position P1 is completed and the turntable 12 starts to rotate together with the wafer W, the rotating grinding wheel 14 is rotated and lowered onto the wafer W, and the wafer W is ground.

Figure 2 is a diagram schematically showing the main structure of the grinding processing part and the surrounding area of the grinding device 10, Figure 2 (a) is a top view showing the structure of the table conveying mechanism 13 and the surrounding area of the measuring mechanism 16, and Figure 2 (b) is a side view showing the structure of the surrounding area of the measuring mechanism 16 together with the rotating grinding wheel 14.

2, the wafer W is attached to a back grinding tape or a supporting substrate 18 such as a glass substrate or a silicon substrate and is held by suction on the turntable 12. The supporting substrate 18 is often used in the grinding process of the wafer W, especially when the wafer W is thin and has a large diameter.

2 is horizontally mounted on the front end of a spindle (not shown). The rotating grinding wheel 14 abuts against the surface of the wafer W which is also rotating while rotating, thereby grinding the surface of the wafer W facing the rotating grinding wheel 14.

Around the grinding position P1 where the turntable 12 is arranged, there is a measuring gauge 19 consisting of a combined reference side gauge 19A and a wafer side height gauge 19B; a shape measuring mechanism 20 is provided for simultaneously measuring the thickness shape in the radial direction and the thickness distribution in the circumferential direction of the ground wafer W.

The reference side gauge 19A of the measuring gauge 19 detects the height position of the turntable 12 by bringing the tip of the swinging reference probe 19a into contact with the upper surface of the turntable 12 not covered by the wafer W. On the other hand, the wafer side height gauge 19B detects the height position of the upper surface of the wafer W by bringing the tip of the swinging variable probe 19b into contact with the upper surface of the wafer W held on the turntable 12, that is, the ground surface. In the measuring gauge 19, the original thickness of the wafer W is measured based on the value obtained by subtracting the measured value of the reference side gauge 19A from the measured value of the wafer side height gauge 19B.

The shape measuring mechanism 20 has a sensor head 20a. Moreover, it is a so-called non-contact (NCIG) measuring mechanism that irradiates light 21 from the sensor head 20a to the wafer W and receives reflected light that interferes with the light reflected on the upper surface of the wafer W. The reflected light is split by a spectrometer, and for example, the control unit 17 described later calculates the thickness shape and circumferential thickness distribution of the wafer W based on the optical path difference between the light reflected on the upper surface of the wafer W and the light reflected on the lower surface of the wafer W. The sensor head 20a is mounted on one end side of the arm 20b, and the other end side of the arm 20b is mounted on the pivot 20c. Specifically, as shown in (a) of Figure 2, a measuring position is set on an imaginary line T of the wafer center O of the wafer W where the sensor head 20a moves with the rotating table 12, and at a position that does not interfere with the rotating grinder 14 and a position that is not affected by the scattering of grinding wastewater from the rotating grinding wheel 14. The shape measuring mechanism 20 may be provided in a state where the sensor head 20a is always fixed at the measuring position P3 on the imaginary line T. In addition, when the sensor head 20a interferes with the movement of the rotating table 12 or the grinding operation of the rotating grinding wheel 14, the sensor head 20a may be temporarily moved and retracted outside the movement path of the rotating table 12. In this embodiment, the sensor head 20a can be moved and retracted.

The control unit 17 is composed of, for example, a CPU and a memory, and determines the thickness shape and thickness distribution of the wafer W according to a pre-installed software program, and controls the overall operation of the grinding device 10. The control unit 17 includes a determination mechanism 17A and a control unit 17B.

The determination mechanism 17A calculates the thickness shape (processing thickness shape) and the circumferential thickness distribution of the wafer W based on the signal detected based on the optical path difference between the light reflected by the shape measuring unit 20 on the upper surface of the wafer W and the light reflected on the lower surface of the wafer W, and determines whether the thickness shape and the circumferential thickness distribution of the wafer W are within a normal range based on the calculated result and a pre-set threshold.

When the determination mechanism 17A determines that there is an abnormality, the control unit 17B issues an alarm and outputs a signal to stop processing of the next wafer W at a necessary position of the grinding device 10 .

Fig. 3 is an operation diagram showing an example of the operation of the grinding processing unit of the grinding device 10. Next, a procedure for measuring the thickness profile in the radial direction and the thickness distribution in the circumferential direction of the wafer W will be described with reference to Fig. 3 .

Before the grinding process of the wafer W, the turntable 12 is arranged at the non-grinding position P2 shown in FIG. 3 (a). At the non-grinding position P2, the wafer W before grinding is placed on the turntable 12, and the placed wafer W is held on the turntable 12 by being clamped by a chuck. Afterwards, as shown in FIG. 3 (b), the turntable 12 moves to the grinding position P1 together with the wafer W by driving the linear motion table 13B of the table conveying mechanism 13. At the grinding position P1, the turntable 12 rotates integrally with the wafer W, and the rotating grinding wheel 14 descends while rotating, pressing on the surface of the rotating wafer W, and the surface grinding of the wafer W begins. In addition, after the prescribed surface grinding is completed, the rotating grinding wheel 14 rises and leaves the wafer W, and stops rotating.

Next, as shown in FIG3(c), the sensor head 20a moves to a position corresponding to the imaginary line T by the operation of the pivot 20c and the arm 20b. Next, as shown in FIG3(d), the rotary table 12 moves the linear motion table 13B to the measurement position P3 by driving the linear motion table 13b so that the wafer center O of the wafer W comes to be directly below the sensor head 20a.

Then, as shown in (e) of FIG. 3 , while the wafer W is rotated in one direction together with the turntable 12, the wafer W and the turntable 12 are moved toward the non-grinding position P2 at a specified speed by driving the linear motion table 13B. At this time, the light 21 is irradiated from the sensor head 20a to the wafer W, and the thickness shape and the circumferential thickness distribution of the wafer W are calculated based on the optical path difference between the light reflected on the upper surface of the wafer W and the light reflected on the lower surface of the wafer W. Here, while the wafer W rotates together with the turntable 12, the wafer center O of the wafer W moves (displaces) on the approximate imaginary line T, so as shown in FIG. 4 , the thickness shape of the wafer W from the wafer center O to the outer peripheral end and across the substantially entire surface of the wafer W can be measured.

FIG4 is a diagram in which the sensor head 20a does not perform measurement continuously but extracts and converts it into data intermittently. In this example, it is an example of data D1 obtained by intermittently measuring the positions of 1500 points of a 4-inch diameter wafer W. In the data D1 shown in FIG4, the thickness of the measurement point is displayed in a spiral shape because the wafer W rotates. In addition, the thickness shape shown in the data D1 is displayed in different colors on a display not shown in the figure according to the size or shape of the thickness at the measurement point.

In addition, the data obtained in FIG4 is produced as three-dimensional map data D2. FIG5 shows an example of converting the data D1 obtained in FIG4 into three-dimensional map data D2. Then, after the measurement is completed, when the wafer W and the turntable 12 return to the non-grinding position P2, they are replaced with unprocessed wafers W, and new grinding processing and production of data D1 and three-dimensional map data D2 are repeated.

Therefore, as shown in this embodiment, by setting the measurement position P3 at a position on the imaginary line T of the wafer center O of the wafer W that moves the sensor head 20a of the shape measuring mechanism 20 together with the rotating table 12 and does not interfere with the rotating grinding wheel 14, the thickness shape in the radial direction and the thickness distribution in the circumferential direction of the wafer W can be measured simultaneously during the period when the rotating table 12 moves from the grinding position P1 to the non-grinding position P2 while rotating together with the wafer W. As a result, compared with the conventional device in which the measurement is performed after the grinding process by moving to the measurement position set at another position, the time for moving from the grinding position to the other measurement position and then returning from the measurement position to the non-grinding position is eliminated, so that the processing time can be shortened. In addition, the cost can be reduced, and the processing time can be shortened, and the productivity can be improved. In addition, the case where the shape measurement of the wafer W by the shape measuring mechanism 20 is performed after the grinding process of the wafer W is described, but if there is no influence of the shape measuring mechanism 20, it can also be performed during the process. In addition, in this embodiment, although a structure is shown in which the wafer W rotating relative to the base 20A is moved on the imaginary line T to displace the measurement position in the radial direction of the wafer W, the sensor head 20a of the shape measuring mechanism 20 can also be moved (displaced) in the radial direction of the wafer W relative to the rotating wafer W.

Next, in the embodiment shown in FIGS. 1 to 3 , an example of the order in which the control mechanism 17 performs the determination (abnormality detection) of the grinding quality of the wafer W to be ground later, using the data D1 obtained in FIG. 4 and the three-dimensional map data D2 converted in FIG. 5 as references, is described through the flowchart shown in FIG. 6 . In addition, in the control example shown in FIG. 6 , the data that will serve as the comparison reference prepared in advance is referred to as the reference data D1, and the three-dimensional map data that will serve as the comparison reference is referred to as the reference three-dimensional map data D2. In addition, in FIG. 6 , the case where a signal is sent from the shape measuring mechanism 20 to the control unit 17B via the determination mechanism 17A is taken as an example.

In Fig. 6, in step S1, the sensor head 20a is used in the measurement operation described in Fig. 3 to measure the thickness shape and circumferential thickness distribution data of the wafer W. The data obtained here is, for example, the same as or similar to the data D1 shown in Fig. 4 .

Next, in the determination mechanism 17A, three-dimensional map data is generated in step S2 based on the measurement data obtained in step S1. The three-dimensional map data obtained here is the same as or similar to the three-dimensional map data D2 shown in FIG. 5. Then, step S3 is performed, and the determination mechanism 17A compares the data obtained in steps S1 and S2 with the pre-made reference data D1 and reference three-dimensional map data D2, respectively, to determine whether the error is within the threshold.

When the error is determined to be within the threshold value by the determination mechanism 17A, an OK signal is sent to the control unit 17B, and the process proceeds to step S4. In addition, the control unit 17B that receives the OK signal controls the grinding device 10 in a manner to process the next new wafer W. On the other hand, when the error is determined to be not within the threshold value, an NG signal is sent from the determination mechanism 17A to the control unit 17B, and the process proceeds to step S5. In addition, the control unit 17B that receives the NG signal issues an alarm, and the operation manager performs necessary processing until the NG matter is removed and resolved, and stops the grinding process of the next new wafer W. In this way, it is possible to prevent defective products from being continuously produced in large quantities. In addition, the general determination conditions for the quality of wafer W are: the overall flatness (TTV) is less than 1μm, and the partial flatness (LTV) is set to less than 0.5μm per 5×5mm. In addition, the threshold value as a determination condition (determination criterion), for example, can also be adjusted and changed according to the type of wafer W.

Fig. 7 is a block diagram showing a modified example of the control unit 17 shown in Fig. 1. The determination unit 17A in the control unit 17 shown in Fig. 7 includes a first determination unit 17Aa and a second determination unit 17Ab.

In Figure 7, the first determination mechanism 17Aa calculates the thickness shape (processing thickness shape) and the circumferential thickness distribution of wafer W based on the signal detected by the optical path difference between the light reflected on the upper surface of wafer W and the light reflected on the lower surface of wafer W by the shape measuring mechanism 20, and determines whether the thickness shape and the circumferential thickness distribution of wafer W are within a normal range based on the calculated result and a pre-set threshold.

The second determination unit 17Ab compares the previous measurement value of the wafer W that skipped the determination by the first determination unit 17Aa with the current measurement value of the wafer W, and continuously determines whether there is a deteriorated portion at the same location, and also determines whether the variation range of the deteriorated portion is greater than a threshold value.

When the first determination unit 17Aa or the second determination unit 17Ab determines that an abnormality has occurred, the control unit 17B issues an alarm and issues a signal to stop processing of the next wafer W at a necessary position of the grinding device 10 .

FIG8 is a flowchart showing another example of the order in which the control unit 17 determines the quality of grinding (abnormality detection) of the wafer W to be ground later, using the data D1 obtained in FIG4 and the three-dimensional map data D2 converted in FIG5 as references. In addition, in the control example shown in FIG8, the data that will serve as a comparison reference made in advance is referred to as reference data D1, and the three-dimensional map data that will also serve as a comparison reference is referred to as reference three-dimensional map data D2. In addition, in FIG8, the case where a signal is sent from the shape measuring mechanism 20 to the control unit 17B via the first determination mechanism 17Aa and the second determination mechanism 17Ab of the determination mechanism 17A is taken as an example.

In Fig. 8, in step S1, the sensor head 20a measures the thickness shape and circumferential thickness distribution data of the wafer W by the measuring operation described in Fig. 3. The data obtained here is, for example, the same or similar data as the data D1 shown in Fig. 4 .

Next, in the first determination unit 17Aa, three-dimensional map data is generated in step S12 based on the measurement data obtained in step S11. The three-dimensional map data obtained here is the same as or similar to the three-dimensional map data D2 shown in FIG. 5. Then, step S13 is performed, and the first determination unit 17Aa compares the data obtained in steps S11 and S12 with the pre-made reference data D1 and reference three-dimensional map data D2, respectively, to determine whether the error is within the threshold.

In the judgment of the first judgment mechanism 17Aa, when it is judged that the error is not within the threshold, an NG signal is sent to the control unit 17B, and the process proceeds to step S15. In addition, the control unit 17B that receives the NG signal issues an alarm, and the operation manager performs necessary processing until the NG issue is removed and resolved, and stops the grinding process of the next new wafer W.

On the other hand, when the error is determined to be within the threshold and the shape is positive in the determination by the first determination mechanism 17Aa, the process proceeds to step S14. In step S14, the second determination mechanism 17Ab compares the measurement value of the wafer W of the last time in which the determination by the first determination mechanism 17Aa was skipped with the measurement value of the wafer W of this time, and continuously determines whether an abnormal shape (deteriorated part) exists in the same part, and whether the variation range of the abnormal shape is above the threshold.

In step S14, when the second determination mechanism 17Ab determines that the variation range is within the threshold, an OK signal is sent to the control unit 17B, and the process proceeds to step S16. In addition, the control unit 17B that receives the OK signal controls the grinding device 10 in a manner to process the next new wafer W. On the other hand, when it is determined that the variation range is not within the threshold, the process proceeds to step S15, and an NG signal is sent to the control unit 17B. In addition, the control unit 17B that receives the NG signal issues an alarm, and the operation manager performs necessary processing until the NG matter is removed and resolved, and stops the grinding process of the next new wafer W. In this way, it is possible to prevent defective products from being continuously produced. In addition, the threshold value used as a determination condition (determination criterion) can also be adjusted and changed, for example, according to the type of wafer W.

In this way, when the first judging mechanism 17Aa and the second judging mechanism 17Ab are used to judge whether the wafer W is good or bad, the following advantages are obtained. For example, as shown in FIG9 , when dust 22 or the like is attached to the adsorption surface of the rotating table 12 and the grinding process is performed with the dust 22 interposed between the wafers W, as shown in FIG9( b ), a concave portion 23 is generated on the surface of the wafer W, or a concave portion 23 and a crack 24 are formed. If the processing is continued without knowing this, a large number of defective products will be generated. However, by providing the second judging mechanism 17Ab, it is possible to appropriately judge whether there are continuous deteriorated parts at the same part, and to judge whether the variation range of the deteriorated parts is correct or not, thereby minimizing the generation of defective products.

In addition, in the embodiments shown in Figures 1 to 3, a structure is described in which a linear motion table 13B is used to make the rotating table 12 and the wafer W move linearly back and forth between the non-grinding position P2 and the grinding position P1. However, the present invention is not limited to linear reciprocating motion. For example, the use of a dividing table can also be applied to a grinding device 10 with rotational motion.

FIG. 10 is a top view schematically showing an example of a grinding device 10 when using a dividing table 30. The dividing table 30 in FIG. 9 rotates around a rotating shaft connected to a motor provided on a table conveying mechanism not shown in the figure, with the center O2 as a fulcrum. Three rotating tables 12 for holding and rotating the wafer W are respectively provided on the dividing table 30. The three rotating tables 12 are provided in such a manner that the wafer center O of the wafer W is arranged on a circular imaginary line T concentric with the center O2. Moreover, the dividing table 30 rotates sequentially through the non-grinding position P2, the rough grinding position P1a, and the fine grinding position P1b using the driving force of the motor of the table conveying mechanism. In addition, a grinding mechanism 15 is respectively provided at the rough grinding position P1a and the fine grinding position P1b, and the grinding mechanism 15 has a rotating grinding wheel 14 for grinding the surface of the wafer W.

The sensor head 20a in the shape measuring mechanism 20 is the same as the embodiment shown in FIGS. 1 to 3. It is a so-called non-contact type (NCIG type) measuring mechanism that irradiates the light 21 from the sensor head 20a to the wafer W and receives the reflected light that interferes with the light reflected on the upper surface of the wafer W. The order of processing the reflected light to perform the quality determination process of the wafer W is the same as the embodiment shown in FIGS. 1 to 8. The measuring position P3 is set on the imaginary line T of the wafer center O of the wafer W that rotates with the indexing table 30 and the rotating table 12 around the center O2 as a fulcrum, and is not interfered with the rotating grinding wheel 14, and is not affected by the scattering of grinding waste water caused by the rotating grinding wheel 14. In this case, the shape measuring mechanism 20 can also be set in a state where the sensor head 20a is always fixed on the imaginary line T to measure the position P3, and when the sensor head 20a becomes an obstacle to the movement of the rotating table 12 or the grinding action of the rotating grinding wheel 14, it can also be temporarily moved and retreated to the outside of the movement path of the rotating table 12. Furthermore, the shape measurement of the wafer W by the shape measurement mechanism 20 may be performed during processing as long as there is no influence of the shape measurement mechanism 20 .

Therefore, even when the wafer W is moved while rotating in one direction together with the rotating table 12 using the indexing table 30 shown in FIG. 10 , if the wafer center O reaches directly below the sensor head 20 a during the movement, the light 21 is irradiated from the sensor head 20 a to the wafer W, and by knowing the optical path difference between the light reflected on the upper surface of the wafer W and the light reflected on the lower surface of the wafer W, the thickness profile and the circumferential thickness distribution of the wafer W can be calculated. In addition, since the wafer W rotates together with the rotating table 12 and the wafer center O of the wafer W moves on the imaginary line T, the thickness profile can be measured on substantially the entire surface of the wafer W from the wafer center O to the outer peripheral end.

In addition, the present invention may be modified in various ways other than the above unless it departs from the spirit of the present invention, and the present invention naturally covers the modified aspects.

Description of the label:

Reference numeral 10 denotes a grinding device;

Reference numeral 11 denotes a housing;

Reference numeral 12 denotes a rotating table;

Reference numeral 13 denotes a table conveying mechanism;

Reference numeral 13B denotes a direct-acting stage;

Reference numeral 14 denotes a rotating grinding wheel;

Reference numeral 15 denotes a grinding mechanism;

Reference numeral 16 denotes a measuring mechanism;

Reference numeral 17 denotes a control unit;

Reference numeral 17A denotes a determination mechanism;

Reference numeral 17Aa denotes a first determination mechanism;

Reference numeral 17Ab denotes a second determination mechanism;

Reference numeral 17B denotes a control unit;

Reference numeral 18 denotes a support plate;

Reference numeral 19 denotes a measuring gauge;

Reference numeral 19A denotes a reference side gauge;

Reference numeral 19B denotes a wafer side height gauge;

Reference numeral 19a denotes a reference probe;

Reference numeral 19b denotes a change probe;

Reference numeral 20 denotes a shape measuring mechanism;

Reference numeral 20a denotes a sensor head;

Reference numeral 20b denotes an arm;

Reference numeral 20c denotes a pivot;

Reference numeral 21 denotes light;

Reference numeral 22 indicates dust;

Reference numeral 23 denotes a recess;

Reference numeral 30 denotes an indexing table;

Symbol D1 represents the reference data;

Symbol D2 represents reference three-dimensional map data;

The symbol O indicates the center of the wafer;

The symbols P, P1, P2, and P3 indicate the grinding positions;

Symbol P1a indicates the rough grinding position;

Symbol P1b indicates the fine grinding position;

The symbol T represents an imaginary line;

Symbol W represents a wafer.

Claims (6)

1. A grinding device, comprising: A rotating table that can hold and rotate the wafer; a table conveying mechanism, the table conveying mechanism moving the rotary table between a grinding position and a non-grinding position; a grinding mechanism having a grinding wheel for grinding the upper surface of the wafer moved to the grinding position; and a measuring mechanism for measuring a thickness of the wafer rotating together with the rotating table; The grinding device continuously grinds a plurality of workpieces, and is characterized in that the above-mentioned measuring mechanism comprises: a shape measuring mechanism for measuring a thickness distribution of the wafer by displacing a measuring position of the wafer in a radial direction of the wafer while the rotating table moves from the grinding position to the non-grinding position; a determination mechanism for determining whether the shape of the wafer is correct or not based on the thickness distribution of the wafer measured by the shape measurement mechanism; and A control unit determines whether to continue or stop the grinding of the wafer based on the determination result of the determination means. 2. The grinding device according to claim 1 is characterized in that the above-mentioned judgment mechanism compares the thickness distributions of the multiple wafers judged to be correctly shaped, and judges whether there is an abnormal shape in the common part of each thickness distribution, and the above-mentioned control unit stops the grinding of the above-mentioned wafer when the above-mentioned judgment mechanism judges that there is an abnormal shape in the common part of each thickness distribution. 3. The grinding device according to claim 1, wherein the measurement position of the wafer by the shape measuring mechanism is located on an imaginary line of the center of the wafer moving from the grinding position to the non-grinding position. 4. The grinding device according to claim 3, wherein the table transport mechanism moves the rotating table in such a manner that the imaginary center line of the wafer becomes a straight line. 5. The grinding device according to claim 3, wherein the table transport mechanism moves the rotating table in such a manner that the imaginary center line of the wafer becomes a circle. 6. The grinding device according to claim 5 is characterized in that the table conveying mechanism moves the turntable in the order of a rough grinding position for rough grinding the wafer, a fine grinding position for fine grinding the wafer, and a non-grinding position for loading and unloading the wafer relative to the turntable.