JP2015102488A - Surface inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for correcting a warp/deflection of a wafer while improving an inspection throughput.SOLUTION: A surface inspection device measures a warp or a deflection at a plurality of positions on a wafer using a height sensor before performing a surface inspection of the wafer, and creates a correction curve by associating a measurement position with a measurement value of the warp or the deflection. The surface inspection device calculates timing for driving a stage Z to correct the warp or the deflection based on information (information of sampling for position confirmation during the inspection) of the inspection sampling position on the wafer and the information of the measurement position of the warp or the deflection on the correction curve. The surface inspection device drives the stage Z according to this timing, and executes the surface inspection of the wafer while adjusting a height of the wafer.

Description

  The present invention relates to a surface inspection apparatus, for example, an inspection apparatus that inspects defects such as foreign matter and scratches present on a wafer.

  In the semiconductor manufacturing process, it is necessary to correctly inspect defects on the wafer in order to manage the yield. In a semiconductor manufacturing process, a surface inspection apparatus inspects a defect on a bare wafer on which a circuit pattern is not formed.

  In the surface inspection apparatus, a wafer is placed on a stage, and a rotating operation and a linear operation are performed while irradiating the wafer with spot light. By this operation, the entire wafer surface can be scanned. Then, the surface inspection apparatus detects the scattered light from the region irradiated with the spot light by a detector such as a photomultiplier tube, and detects a defect by performing threshold processing on the detection result. For example, in Patent Document 1, a substrate inspection apparatus uses a plurality of height measuring instruments to measure the warpage of the substrate during the inspection, and drives the stage Z at both ends of the image sensor according to the warpage. It is disclosed to inspect while keeping the sensor parallel.

JP-A-6-109648

  The surface inspection apparatus performs inspection by irradiating the wafer surface with spot light. This spot light is condensed using a lens. For this reason, if the wafer is warped or deflected, the irradiation position is shifted, defocusing occurs, and the sensitivity is lowered. In the above-mentioned Patent Document 1, as described above, the influence of wafer warpage and deflection is eliminated.

  However, in Patent Document 1, warpage and deflection are corrected in accordance with a correction curve generated every time light reaches a wafer inspection position. For this reason, although the influence of warpage and deflection can be removed, the throughput is poor and inspection time is required.

  The present invention has been made in view of such circumstances, and provides a technique for correcting wafer warpage and deflection while improving inspection throughput.

  In order to solve the above problems, in the present invention, first, the amount of warpage and deflection is measured at a plurality of locations on the wafer surface before inspection. Based on the measurement data, the amount of warpage and deflection of the entire wafer is estimated. Based on the estimated amount of warpage and deflection of the entire wafer, the stage is driven in the height direction at the time of inspection to correct the height variation of the wafer due to warpage and deflection.

  More specifically, the surface inspection apparatus measures warpage or deflection at a plurality of positions on the wafer using a height sensor before the surface inspection of the wafer, and based on the measurement result, the warpage or A correction curve is generated by associating the measurement position of the deflection with the measurement value. Then, the surface inspection apparatus corrects the warp or the deflection based on the information on the inspection sampling position on the wafer (information on the sampling for confirming the position during the inspection) and the information on the measurement position of the warp or the deflection on the correction curve. The stage Z drive timing for the above is calculated. In accordance with this timing, the surface inspection apparatus drives the stage Z and performs wafer surface inspection while adjusting the height of the wafer.

Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. The embodiments of the present invention can be achieved and realized by elements and combinations of various elements and the following detailed description and appended claims.
It should be understood that the description herein is merely exemplary and is not intended to limit the scope of the claims or the application of the invention in any way.

  According to the present invention, it is possible to improve both inspection throughput and correction of wafer warpage and deflection.

It is a figure showing the schematic structure of the surface inspection system by the embodiment of the present invention. 5 is a flowchart for explaining an inspection sequence of a wafer 105. 10 is a flowchart for explaining details of a wafer deflection measurement process in step 206; 3 is a schematic diagram showing a concept of deflection of a wafer 105. FIG. 10 is a flowchart for explaining details of a deflection correction table creation process in step 208; It is a schematic diagram of the deflection | deviation correction table preparation process by back surface adsorption | suction. 10 is a flowchart for explaining details of height adjustment processing based on a correction table in step 210; It is the figure which modeled the mode of deflection correction. It is a schematic diagram which shows the mode of the deflection | deviation measurement of the wafer in back surface adsorption | suction. It is a schematic diagram of an edge grip. It is a flowchart for demonstrating the preparatory process performed before performing a deflection | deviation measurement theory, when using an edge grip. It is a flowchart for demonstrating the deflection correction table creation process at the time of using an edge grip system. It is a schematic diagram which shows the mode of a deflection measurement of the wafer at the time of using an edge grip system. It is a schematic diagram which shows the concept of a deflection | deviation correction | amendment when stage R101 drives at high speed. It is a schematic diagram which shows the concept of a deflection | deviation correction | amendment when stage R101 drives at low speed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be denoted by the same numbers. The attached drawings show specific embodiments and implementation examples based on the principle of the present invention, but these are for understanding the present invention and are not intended to limit the present invention. Not used.

  This embodiment has been described in sufficient detail for those skilled in the art to practice the present invention, but other implementations and configurations are possible without departing from the scope and spirit of the technical idea of the present invention. It is necessary to understand that the configuration and structure can be changed and various elements can be replaced. Therefore, the following description should not be interpreted as being limited to this.

  Furthermore, the embodiment of the present invention may be implemented by software running on a general-purpose computer, or may be implemented by dedicated hardware or a combination of software and hardware.

  In the following description, the embodiment of the present invention will be described using the expression “correction table”. However, the embodiment does not necessarily have to be represented by a data structure using a table. It may be expressed in other than. Therefore, it may be simply called “correction information” to indicate that it does not depend on the data structure.

  In the following, each process in the embodiment of the present invention will be described with “controller (processor)” as the subject (operation subject). However, as a description with each program as an operation subject, a name is given to the program corresponding to each flowchart. Also good. A part or all of the program may be realized by dedicated hardware or may be modularized. Various programs may be installed in each computer by a program distribution server or a storage medium.

(1) First Embodiment <Configuration of Surface Inspection System>
FIG. 1 is a diagram showing a schematic configuration of a surface inspection system according to an embodiment of the present invention. The surface inspection system 100 includes a surface inspection device and a transfer device. The surface inspection apparatus includes a stage R101, a stage Z102, a spindle 103, a chuck 104 for fixing the wafer 105 to the stage, an irradiation unit 106 for irradiating the wafer 105 with the beam 107, and scattering from the wafer 105. A detection unit 109 that detects the light 108, a defect extraction unit 110, a controller 111, a height sensor 112, and an outer periphery detection sensor 113 are included. The transfer device includes a transfer unit 114 that transfers the wafer 105 to the surface inspection device, a transfer robot 115, a hand 116 of the transfer robot 115, a load port 117 for placing a storage container 118 for storing the wafer 105, have.

  The stage R101 moves the wafer 105 to be inspected in the R direction. The stage Z102 moves the wafer 105 in the Z direction and adjusts the height of the wafer 105. Stage Z102 is placed on stage R101.

  The spindle 103 rotates the wafer 105. The spindle 103 is placed on the stage Z102. The chuck 104 holds the wafer 105. The chuck 104 is placed on the spindle 103.

  The irradiation unit 106 irradiates the wafer 105 with the beam 107. The beam 107 is scattered on the wafer 105, and scattered light 108 is generated. The generated scattered light 108 is detected by the detection unit 109. The defect extraction unit 110 performs a defect detection process on the wafer 105 from the data of the detection unit 109. In addition, the defect extraction unit 110 acquires encoder values of the stage R101 and the spindle 103, and also calculates the coordinates of the detected defect. The defect data detected by the defect extraction unit 110 is sent to the controller 111.

  The controller 111 includes an input device such as a keyboard and a mouse, an output device such as a flat panel display, and a control unit (processor) that controls each part of the device. The user operates the controller 111 to set inspection conditions and confirm inspection results. The controller 111 may be configured with a normal computer.

  The transport unit 114 of the transport device is adjacent to the surface inspection device. The transfer unit 114 takes out the wafer 105 stored in the storage container 118 and transfers it to the inside of the surface inspection apparatus. More specifically, the load port 117 is installed in the transport unit 114. The storage container 118 storing the wafer 105 is placed on the load port 117. The transfer robot 115 inside the transfer unit 114 is driven to take out the wafer 105 from the storage container 118 using the hand 116 and transfer it into the surface inspection apparatus.

  The controller 111 drives the stage R101 and moves it to the wafer delivery position 119. The wafer 105 transported into the surface inspection apparatus is placed on the chuck 104. Thereafter, the controller 111 drives the stage R101 to move the wafer 105 to the height measurement position 120. Then, the controller 111 uses the height sensor 112 to measure the distance from the height sensor 112 to the surface of the wafer 105. Based on the measurement result, the controller 111 drives the stage Z102 to adjust the height.

  In addition, the controller 111 drives the stage R101 to move the wafer 105 to the outer periphery detection position 121. Then, the controller 111 rotates the spindle 103 and measures the outer circumference data of the wafer 105 by the outer circumference detection sensor 113. The measurement of the outer circumference data is performed in order to measure how much the wafer 105 is shifted in the XY direction of the two-dimensional plane when the wafer 105 is placed on the chuck 104. Then, the controller 111 calculates the placement position of the wafer 105 on the chuck 104 from the outer periphery data.

The controller 111 transmits the calculated wafer 105 placement position data to the defect detection unit 110.
Thereafter, the controller 111 drives the stage R101, moves the wafer 105 to the inspection start position 122, and starts inspection.

<Wafer inspection processing>
FIG. 2 is a flowchart for explaining the inspection sequence of the wafer 105. FIG. 2 shows an inspection sequence in the case where the chuck 104 is of the back surface adsorption type.

(I) Step 201
The hand 116 takes out the wafer 105 from the storage container 118, transports it into the surface inspection apparatus, and places the wafer 105 on the chuck 104.

(Ii) Step 202
The controller 111 drives the stage R101 to move the wafer 105 to the height measurement position 120 and measures the distance from the sensor to the wafer 105 using the height sensor 112.

(Iii) Step 203
The controller 111 drives the stage R101 to move the wafer 105 to the outer periphery detection position 121. Then, the controller 111 rotates the spindle 103 and measures the outer periphery of the wafer 105 using the outer periphery detection sensor 113. At this time, the controller 111 calculates the mounting position of the wafer 105 with respect to the chuck 104 based on the outer circumference measurement data. By the processing in step 203, the coordinates of the wafer 105 are determined.

(Iv) Step 204
The controller 111 drives the stage Z102 to move the wafer 105 to the height at the time of inspection in order to measure the deflection in the same state as at the time of inspection. Further, the controller 111 rotates the spindle 103 and rotates the wafer 105 at the rotation speed at the time of inspection.

(V) Step 205
The controller 111 drives the stage R101 to start moving the wafer 105 from the outer periphery detection position 121 in the direction in which the inspection start position 122 is located.

(Vi) Step 206
While moving the wafer 105 from the outer periphery detection position 121 to the inspection start position 122, the controller 111 stops driving the stage R101 several times. Each time, the height sensor 112 is used to measure the height to the surface of the wafer 105. Details of this step will be described later (see FIG. 3).

(Vii) Step 207
The controller 111 drives the stage R101 to move the wafer 105 to the inspection start position 122.

(Viii) Step 208
The controller 111 calculates the amount of deflection in the entire area of the wafer 105 based on the height data measured using the height sensor 112 in step 206. From the calculated result, a deflection correction table is created in which the relationship between the R coordinate on the wafer 105 and the amount of deflection at that location is summarized. Details of this step will be described later (see FIG. 5).

(Ix) Step 209
The controller 111 irradiates the wafer 105 with the beam 107 from the irradiation unit 106 and starts inspection.

(X) Step 210
Based on the deflection correction table created in step 208, the controller 111 drives the stage Z102 to adjust the height. This step will also be described later (see FIG. 7A).

(Xi) Step 211
The controller 111 ends the inspection.

(Xii) Step 212
The hand 116 of the transfer apparatus collects the wafer 105 that has been inspected from the chuck 104 and returns it to the storage container 118.

<Details of deflection measurement processing>
FIG. 3 is a flowchart for explaining details of the wafer deflection measurement process in step 206.

(I) Step 301
The controller 111 uses the height sensor 112 to measure the height of the wafer 105 when the wafer 105 is at the outer periphery detection position 121. At this time, the encoder value of the stage R101 is acquired and managed together with the height data.

(Ii) Step 302
The controller 111 drives the stage R101 to move the wafer 105 by a predetermined amount in the direction of the inspection start position 122 in order to measure the height of the wafer 105 at a location different from the location performed at step 301.

(Iii) Step 303
As in step 301, the controller 111 measures the height of the wafer 105 using the height sensor 112. Also at this time, the encoder value of the stage R101 is acquired, and the height measurement position and the height measurement data on the wafer 105 are managed as a set.

(Iv) Repetitive processing The controller 111 repeatedly executes the processing of steps 302 and 303 a predetermined number of times.

(V) Step 304
The controller 111 drives the stage R101 and moves the wafer 105 to the inspection start position 122.

  If the wafer delivery position 119, the height measurement position 120, and the outer periphery detection position 121 are the same position, the area of height measurement performed in steps 301 and 303 can be widened.

<Concept of deflection>
FIG. 4 is a schematic diagram illustrating the concept of deflection of the wafer 105.
As shown in FIG. 4, when the chuck 104 is smaller than the wafer 105, the wafer 105 protrudes from the chuck 104. In the protruding portion, warpage or deflection may occur due to the weight of the wafer 105 or buoyancy generated during rotation. In addition, warping / deflection may occur even at the portion held by the chuck 104.

  Due to the influence of such warpage and deflection, the height of the wafer 105 may not be uniform from the wafer center to the outer periphery. In particular, the influence of warpage and deflection appears greatly on the chuck boundary and on the outside of the chuck.

  For this reason, height data is densely acquired at these portions, and the amount of warpage and deflection is measured. By summarizing the distance from the center of the wafer 105 and the amount of deflection at each location, a deflection curve 401 can be generated.

<Deflection correction table>
FIG. 5 is a flowchart for explaining details of the deflection correction table creation processing in step 208. FIG. 6 is a schematic diagram of a deflection correction table creation process for backside suction.

(I) Step 501
The controller 111 converts the height data of the wafer 105 measured in step 206 and the measurement coordinates on the stage R101 into a coordinate space with the center of the wafer 105 as the origin according to the equation (1).

(Formula 1)
_{(R i, z i) =} (r 'i -r' c, z 'i) ··· (1)
Here, r ^′ _i is the encoder value of the stage R101 at the position where the height is measured, r ′ _c is the encoder value of the stage R101 when the height at the center of the wafer 105 is measured, z ^′ _i is the measured height data, r _i is the R coordinate value with the center of the wafer 105 as the origin, and z _i is the height data at r _i .

(Ii) Step 502
The controller 111 subtracts the height data measured in step 301 from the height data z _i obtained in step 501 to obtain a deflection amount.

(Iii) Step 503
The controller 111 linearly interpolates between the data obtained in step 502, and obtains the deflection amount on the R axis of the wafer 105 with a constant step size. Using the distance from the center of the wafer 105 and the amount of deflection at that position as a set of data, a deflection correction table is created in which the amounts of deflection in the entire R axis of the wafer 105 are summarized.

  As shown in FIG. 6, the amount of deflection is roughly measured within a predetermined distance from the center of the wafer 105 to the front of the outer periphery of the chuck 104, and the amount of fine deflection is measured after the front of the outer periphery of the chuck 104 (outside the predetermined distance from the center). A deflection correction table is generated as measured.

<Height adjustment process>
FIG. 7A is a flowchart for explaining the details of the height adjustment processing based on the correction table in step 210. This process is continuously executed from the start of the inspection in step 209 to the end of the inspection in step 211. FIG. 7B is a diagram schematically illustrating the state of deflection correction.

The sampling step for the position confirmation (the interval between R _i and R _{i + 1} in FIG. 7B) is larger than each inspection step (the sampling step is a fixed value (usually in the order of millimeters) determined by the apparatus). The step is a micro-order value determined by the user.) If the deflection is corrected while checking the position at each inspection position, a very accurate deflection correction can be realized, but on the other hand, the throughput deteriorates and the inspection time takes a long time. Therefore, the present invention improves the throughput while realizing accurate deflection correction to some extent while following the correction curve as much as possible using information on the sampling position (current sampling position and predicted sampling position). . Specifically, the deflection correction is executed according to the thick line in FIG. 7B. Although the correction amount is not more accurate than realizing the deflection correction according to the obtained correction table (deflection correction amount), the throughput is better than the deflection correction according to the correction table.

(I) Step 701
The controller 111 calculates the R coordinate R _i (sampled inspection point for position confirmation: see FIG. 7B) currently being inspected on the wafer 105. This is calculated from the amount of movement of the stage R101 from the start of inspection to the present.

  The amount of movement of the stage R101 may use the encoder value of the stage R101, or may be calculated from the driving time from the start of inspection. A conversion formula from the coordinate system of the stage R101 to the coordinate system based on the center of the wafer 105 is as shown in the equation (2).

(Formula 2)
R _i = R _e −R _s (2)
Here, R _i is the inspection position on the wafer, R _e is the coordinates of the stage R 101, and R _s is the coordinates of the stage R 101 during the center inspection of the wafer 105.

(Ii) Step 702
The controller 111 predicts the next R coordinate R _{i + 1} (sampling inspection point for the next position confirmation) on the wafer 105 when step 701 is executed. The prediction can be calculated from the time until the next inspection position acquisition and the moving speed at the time of inspection in the stage R101. Actually, there are a large number of inspection points between the sampling points _Ri and _{Ri + 1} .

(Iii) Step 703
The controller 111 determines whether or not the step of the correction table is located between R _i and R _{i + 1} obtained in steps 701 and 702. For example, if R _i = 10.9 mm, R _{i + 1} = 11.3 mm, and the step point is nmm (n is an integer), 10.9 ≦ n ≦ 11.3, so between R _i and R _{i + 1} , This means that the score points of the correction table are located. If the condition is Yes, the process proceeds to step 704, and if the condition is No, the process proceeds to step 701.

(Iv) Step 704
The controller 111 acquires the amount of deflection at the inspection position R _i on the wafer 105 calculated in Step 701 from the deflection correction table obtained in Step 503. For example, when R _i is 5 mm, the amount of deflection at a location where the distance from the wafer center is 5 mm is acquired in the deflection correction table. If the amount of deflection is within the allowable range, the process proceeds to step 701 without doing anything. If the amount of deflection is outside the allowable range, the process proceeds to step 705.

(V) Step 705
The controller 111 calculates the timing for starting the deflection correction driving in consideration of the deflection correction operation time and the delay time.

As shown in FIG. 7B, it is necessary to move the stage Z102 so as to follow the correction table as much as possible. Therefore, the controller 111 calculates at which timing (time) the deflection correction is to be driven from the current position R _i by using Expression (3).

(Formula 3)
T = T _r + (T _n −T _z ) / 2−T _d (3)
Here, T _r is the movement time of the stage R101 from the current position R _i to the next correction table step, T _n is the time required for the stage R101 to move from the correction table step _{n to n} + 1, and T _z Is the time required for the stage Z102 to be driven by the deflection correction amount (including the delay time of the stage Z102 from when the stop instruction is received until it stops), and _Td is when the stage Z102 receives the correction start instruction It is the time (delay time) from the start to the operation start.

(Vi) Step 706
The controller 111 waits for the timing T (time) calculated in step 705, and issues an execution instruction for the correction operation to the stage Z102.

(Vii) Step 707
The controller 111 operates the stage Z102 by the correction amount obtained in step 704. Since there is an operation delay in the stage Z102, even if the correction operation execution is instructed at the timing T, the actual correction is performed _Td after the correction operation execution instruction.

(Viii) Repetition Processing Thereafter, the controller 111 repeats the processing from step 701 to step 707 until the inspection is completed.

(2) Second Embodiment The second embodiment relates to a deflection correction table creation process when the measurement position of the height sensor 112 is different from that on the R axis of the wafer 105.

  In the inspection, since the beam 107 irradiated from the irradiation unit 106 is irradiated on the R axis of the wafer 105, the deflection correction table needs to be on the R axis of the wafer 105.

  However, when the height measurement location and the R axis of the wafer 105 are different, it is necessary to predict the deflection correction table on the R axis of the wafer 105 in consideration of the distance between the measurement location and the R axis of the wafer 105.

  FIG. 8 is a schematic view showing a state of measuring the deflection of the wafer in the back surface adsorption. In the second embodiment, as shown in FIG. 8, the measurement is performed roughly until the outer periphery of the chuck 104 (within a predetermined distance from the center of the wafer 105), and thereafter, the measurement is made finely. This is the same as in the first embodiment, but the measurement position needs to be converted on the R axis passing through the center. The conversion formulas are formulas (4) and (5) described later.

  The correction table creation process according to the second embodiment is the same as the correction table creation process of FIG. 5 shown in the first embodiment. The difference between the first embodiment and the second embodiment is the calculation formula used in step 501.

  In the second embodiment, in step 501, the controller 111 uses a prediction calculation formula (formula (4) or formula (5)) based on the height data / measurement location information of the wafer 105 measured in step 206. Thus, the height of the wafer 105 on the R axis is predicted.

First, assuming that the location held by the chuck 104 in the wafer 105 is flat, that is, when r ^′ _i is the R coordinate on the wafer at the location where the height is measured, 0 ≦ r ^′ _i ≦ chuck. In the case of the radius of 104, using the measurement data on the chuck 104, the calculation formula is as shown in Formula (4).
(Formula 4)
(R _i , z _i ) = (r ^′ _i , z ^′ _i ) (4)

Next, a calculation formula that can be applied to the data of all measurement points is as shown in Formula (5) when 0 ≦ r ^′ _i ≦ the radius of the wafer 105.
(Formula 5)
_{(R i, z i) =} (√ (a ^ 2 + (r 'i) ^ 2), z' i) ··· (5)
Here, a is the distance between the height measurement location and the R axis of the wafer 105, z ^′ _i is the measured height data, r _i is the R coordinate on the R axis of the wafer 105, and z _i is the R axis of the wafer 105. The height data above.

(3) Third Embodiment The third embodiment relates to a deflection correction process when the chuck 104 is an edge grip type.

  FIG. 9 is a schematic diagram of an edge grip. The edge grip system has a mechanism for holding and fixing the outer periphery of the wafer 105 with claws. In order to reduce the deflection at the center of the wafer, air is blown from below to the vicinity of the center of the wafer 105.

<Inspection sequence>
An inspection sequence when the chuck 104 is an edge grip type will be described. Even when the chuck 104 is of the edge grip type, the entire inspection sequence is almost the same as the flowchart shown in FIG. 2, but only the processing in step 204 and step 208 is different from that in the back surface suction.

(I) Step 204
The controller 111 sets the height and the number of rotations of the wafer 105 at the time of inspection in order to measure the deflection of the wafer 105 in the same state as at the time of inspection.

FIG. 10 is a flowchart for explaining a preparation process that is executed before the deflection measurement when the edge grip is used.
In step 1001, the controller 111 drives the stage Z102 to move the wafer 105 to a predetermined height position to be inspected.
In step 1002, the controller 111 rotates the spindle 103 and rotates the wafer 105 at the rotation speed at the time of inspection.
In step 1003, the controller 111 starts spraying air on the wafer 105 at a flow rate at the time of inspection.
Deflection measurement becomes possible after executing the processing of steps 1001 to 1003 described above.

(Ii) Step 208
The controller 111 creates a deflection correction table for the wafer 105 based on the deflection data measured in step 206.

  FIG. 11 is a flowchart for explaining deflection correction table creation processing when the edge grip method is used. FIG. 12 is a schematic diagram showing the state of wafer deflection measurement when the edge grip method is used. When the edge grip method is used, the overall height measurement is performed more finely than when the back surface suction method shown in FIGS. 6 and 8 is used. If the height measurement location is not on the R axis of the wafer, it is necessary to convert the measurement location to coordinates on the R axis, as in FIG.

  In step 1101, the controller 111 predicts the height of the wafer 105 on the R axis based on the height data / measurement location of the wafer 105 measured in step 206. The calculation formula for prediction is the formula (5) shown in the second embodiment. In the second embodiment, since there is almost no deflection on the chuck, the equation (4) can be used. However, in the edge grip method, the amount of deflection changes depending on the distance from the wafer center. (4) cannot be used.

  In step 1102, the controller 111 obtains the amount of deflection by taking the difference between the height data on the R axis of the wafer 105 obtained in step 1101 and the height data measured in step 301.

  Next, in step 1103, the controller 111 obtains a deflection amount inflection point and local maximum / minimum values in the inner peripheral portion of the wafer based on the data obtained in step 1102 and the air spray position.

  In step 1104, the controller 111 interpolates between the deflection data obtained in steps 1102 and 1103, and obtains the deflection amount on the R axis of the wafer 105 with a constant step size. Further, the controller 111 creates a deflection correction table in which the deflections in the entire R-axis of the wafer 105 are collected using the distance from the wafer center and the deflection amount at that position as one set of data.

(4) Fourth Embodiment In the fourth embodiment, in the stage height adjustment process in step 210 described above, the interval for checking the inspection position on the wafer 105 in step 701 is larger than the interval in the deflection correction table. Further, the present invention relates to a deflection correction process for improving the follow-up performance of the deflection correction.

  FIG. 13 is a schematic diagram showing the concept of deflection correction when the stage R101 is driven at high speed.

Here, the inspection position at the current sampling (sampling for checking the current position during inspection) is R _i , and the inspection position at the next sampling is R _{i + 1} . In this case, the correction for the sections n to n + 1 of the deflection correction table can be performed, but the correction for the sections n + 1 to n + 2 is lost. Therefore, in the fourth embodiment, in order to avoid the occurrence of missing deflection correction, after correction of the sections n to n + 1, after an appropriate interval, correction for the sections n + 1 to n + 2 is also performed. Control.

  The deflection correction process according to the fourth embodiment is the same as the deflection correction process according to the first embodiment (FIG. 7A).

(I) Steps 701 and 702
The controller 111 executes steps 701 and 702 to calculate the current inspection position R _i and the inspection position R _{i + 1} at the next sampling.

(Ii) Step 705
When a plurality of sections are included between R _i and R _{i + 1} , the controller 111 calculates a correction drive start timing for each section. Formula for timing for ticks position of the current position R when viewed from the _i of the m-th correction table is as shown in equation (6).

(Formula 6)
T (m) = T _r + T _n (1) +... + T _n (m−1)
+ (T _n (m) −T _z (m)) / 2−T _d (6)
Here, T _r is the moving time of the stage R101 from the current position R _i to the nearest correction table step position (sledge / deflection measurement point), and T _n (x) is the step interval x to x + 1 of the correction table of the stage R101. , T _z (x) is the time required for the stage Z102 to drive the deflection correction amount in the step interval x to x + 1 of the correction table, and T _d is the instruction for the stage Z102 to start correction It is the time (delay time) from the start to the start of operation.

(Iii) Step 706
The controller 111 waits for the timing T (m) time calculated in step 705, and issues an instruction to execute the correction operation to the stage Z102 when the time has elapsed.

(Iv) Step 707
The controller 111 operates the stage Z102 by the correction amount obtained in step 704.
The controller 111 repeats the processing of steps 706 and 707 for the number of sections of the correction table included between R _i and R _{i + 1} .

(V) Repetition Processing Subsequently, the controller 111 repeats the processing from steps 701 to 707 until the inspection is completed.

(5) Fifth Embodiment In the fifth embodiment, in the stage height adjustment process in step 210 (FIG. 2), the stage R101 is driven at a lower speed than the confirmation sampling period of the inspection position of the wafer 105. The present invention relates to improvement in followability when the deflection correction operation can be performed a plurality of times. The deflection correction process is executed according to the flowchart of FIG. 7A as in the first embodiment. In the following, only processing contents different from those in FIG. 7A will be described.

  FIG. 14 is a schematic diagram showing the concept of deflection correction when the stage R101 is driven at a low speed. As shown in FIG. 14, when the inspection position can be confirmed a plurality of times in the sections n to n + 1 of the deflection correction table, the deflection correction table is divided into two rather than performing the deflection correction operation at once. The followability can be improved.

(I) Step 701
The controller 111 obtains the current inspection position (sampling point for position confirmation) R _i .

(Ii) Step 702
The controller 111 calculates the number of samplings within the section of the deflection correction table from the driving speed of the stage R101. Further, the controller 111 divides the deflection amount by the number of samplings, and calculates the deflection correction amount per operation.

(Iii) Step 705
The controller 111 calculates the correction operation start timing based on the divided correction amount.

(Iv) Steps 706 and 707
The controller 111 executes the standby until the operation start timing (step 706) and the height adjustment processing of the wafer 105 (step 707) as many times as the number of divisions.

(6) Summary (i) As described above, the present invention does not simply correct warpage or deflection at each inspection point in accordance with a deflection correction table (correction curve). This is because if the correction is performed according to the correction curve, the throughput may be deteriorated. The present invention analyzes the relationship between the correction curve and the sampling position (position included in the inspection point) for position confirmation, determines the movement start timing and stop timing of the stage Z, and determines the stage Z according to this timing. The inspection is performed by driving (see FIGS. 8, 13 and 14).

  That is, the surface inspection apparatus measures the warpage or deflection at a plurality of positions on the wafer using the height sensor before the surface inspection of the wafer, and determines the measurement position of the warpage or deflection based on the measurement result. A correction curve (deflection correction table) is generated by associating the measured values. Then, the surface inspection apparatus is based on the information on the inspection sampling position on the wafer (sampling information for position confirmation during inspection) and the information on the measurement position (measurement point) of the warp or deflection in the correction curve, Stage Z driving timing for warping or deflection correction is calculated (more specifically, when there is a measurement point between the current inspection sampling position and the next inspection sampling position, stage Z is calculated. Calculate the drive timing). In accordance with this timing, the surface inspection apparatus drives the stage Z and performs wafer surface inspection while adjusting the height of the wafer. By doing so, it is possible to correct the generated correction curve so as to follow the warp / deflection and improve the inspection throughput. That is, conventionally, when the warp / deflection correction is performed, the inspection throughput is sacrificed. However, according to the present invention, both the warp / deflection correction and the inspection throughput can be improved. Further, since a correction curve is obtained for each individual wafer before the wafer inspection, it becomes possible to execute the warp / deflection correction corresponding to the warp / deflection amount of each wafer. In addition, the amount of warpage / deflection across the entire wafer is calculated from measurement data of warpage / deflection at multiple locations, so that the accuracy of warpage / deflection and maintenance time can be shortened. Become. Further, the sensitivity of detection defects can be stabilized over the entire wafer area by correcting the warpage and deflection.

  Further, when calculating the timing, the surface inspection apparatus further obtains the amount of warpage or deflection of the wafer at the current inspection sampling position from the correction curve, and when the obtained amount of warpage or deflection exceeds a predetermined allowable range. Then, the stage Z drive timing is calculated. As a result, the stage Z can be driven only when the deflection amount is outside the allowable range, so that the surface inspection can be performed efficiently. Note that when calculating the timing, the timing may be calculated in consideration of the operation delay of the stage Z. By doing so, it becomes possible to perform warp / deflection correction following the correction curve.

(Ii) The correction curve is generated based on the amount of warpage or deflection at a plurality of positions on the R axis of the wafer. Accordingly, the movement and consistency of the stage R can be maintained, and the warp / deflection correction can be executed more accurately.

  When the measurement point of warpage or deflection is not on the R axis of the wafer, the surface inspection apparatus converts the coordinates of the measurement point into coordinates on the R axis of the wafer to generate a correction curve. By doing so, the movement and consistency of the stage R can be maintained wherever the measurement point is on the wafer.

(Iii) In the present invention, when the stage R is driven at a higher speed and at a lower speed than the sampling period for checking the inspection position, different operations are executed. In the former case, when calculating the timing, the surface inspection device determines that there are multiple warp or deflection measurement positions between the current inspection sampling position and the next inspection sampling position. The stage Z drive timing is calculated for each of the plurality of warp or deflection measurement positions. By doing this, it is possible to prevent the warp / deflection correction from being lost when the stage Z is driven at high speed, and to accurately follow the correction curve and execute the warp / deflection correction.

  On the other hand, in the latter case, when there are a plurality of inspection sampling positions between two warp or deflection measurement positions, the surface inspection apparatus performs correction determined by the amount of warpage or deflection at the two warp or deflection measurement positions. The amount is divided by the number of samplings between two warp or deflection measurement positions to calculate a division correction amount, and the stage Z drive timing is calculated based on the division correction amount. By doing in this way, the followability with respect to a correction curve can be improved more.

(Iv) The present invention can also be realized by software program codes that implement the functions of the embodiments. In this case, a storage medium in which the program code is recorded is provided to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus reads the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code itself and the storage medium storing the program code constitute the present invention. As a storage medium for supplying such program code, for example, a flexible disk, CD-ROM, DVD-ROM, hard disk, optical disk, magneto-optical disk, CD-R, magnetic tape, nonvolatile memory card, ROM Etc. are used.

  Also, based on the instruction of the program code, an OS (operating system) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing. May be. Further, after the program code read from the storage medium is written in the memory on the computer, the computer CPU or the like performs part or all of the actual processing based on the instruction of the program code. Thus, the functions of the above-described embodiments may be realized.

  Further, by distributing the program code of the software that realizes the functions of the embodiment via a network, it is stored in a storage means such as a hard disk or memory of a system or apparatus, or a storage medium such as a CD-RW or CD-R And the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage means or the storage medium when used.

  Finally, it should be understood that the processes and techniques described herein are not inherently related to any particular apparatus, and can be implemented by any suitable combination of components. In addition, various types of devices for general purpose can be used in accordance with the teachings described herein. It may prove useful to build a dedicated device to perform the method steps described herein. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined. Although the present invention has been described with reference to specific examples, these are in all respects illustrative rather than restrictive. Those skilled in the art will appreciate that there are numerous combinations of hardware, software, and firmware that are suitable for implementing the present invention. For example, the described software can be implemented in a wide range of programs or script languages such as assembler, C / C ++, perl, shell, PHP, Java (registered trademark).

  Furthermore, in the above-described embodiment, control lines and information lines are those that are considered necessary for explanation, and not all control lines and information lines on the product are necessarily shown. All the components may be connected to each other.

  In addition, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and embodiments of the invention disclosed herein. Various aspects and / or components of the described embodiments can be used singly or in any combination in a computerized storage system capable of managing data. The specification and specific examples are merely exemplary, and the scope and spirit of the invention are indicated in the following claims.

101 ... Stage R
102 ... Stage Z
103 ... Spindle
104 ... Chuck
105 ... Wafer
106 ... Irradiation part
107 ... Beam
108 ... scattered light
109 ... Detection unit
110: Defect extraction unit
111 ... Controller
112 ... Height sensor
113 ... Outer periphery detection sensor 114 ... Conveying section
115: Transfer robot
116 ... hand
117 ... Load port
118 ... Container
119: Wafer delivery position 120: Height measurement position
121 ... Outer periphery detection position 122 ... Inspection start position

Claims (10)

A surface inspection apparatus for inspecting the surface of a wafer,
A first stage for moving the wafer in the R direction;
A second stage for moving the wafer in a height direction;
A height sensor,
Prior to surface inspection of the wafer, the height sensor is used to measure warpage or deflection at a plurality of positions on the wafer, and based on the measurement results, the measurement position and measurement value of the warp or deflection are determined. A processor that generates a correction curve in response,
A memory for storing the generated correction curve as warp / deflection correction information,
The processor is
The warp / deflection correction information is read from the memory, and the warp / deflection correction is performed based on the information on the inspection sampling position on the wafer and the information on the measurement position of the warp or deflection on the correction curve. A process of calculating the stage drive timing of No. 2,
A process of driving the second stage according to the calculated timing and adjusting the height of the wafer;
The surface inspection apparatus characterized by performing. In claim 1,
In the process of calculating the timing, the processor calculates the timing of the second stage drive when the measurement position of the warp or the deflection exists between the current inspection sampling position and the next inspection sampling position. A surface inspection apparatus characterized by calculating. In claim 2,
In the process of calculating the timing, the processor further obtains the warpage or deflection amount of the wafer at the current inspection sampling position from the correction curve, and the obtained warpage or deflection amount exceeds a predetermined allowable range. In addition, the surface inspection apparatus calculates the timing of driving the second stage. In claim 1,
The surface inspection apparatus, wherein the processor calculates the timing of driving the second stage in consideration of the operation delay of the second stage in the process of calculating the timing. In claim 1,
The surface inspection apparatus, wherein the processor measures the warp or deflection at a plurality of positions on the R-axis of the wafer and generates the correction curve. In claim 1,
When the measurement position of the warp or deflection is not on the R axis of the wafer, the processor converts the coordinates of the measurement position into coordinates on the R axis of the wafer to generate the correction curve. A featured surface inspection device. In claim 1,
The surface inspection apparatus, wherein the wafer is placed on a chuck by back surface adsorption. In claim 1,
The surface inspection apparatus, wherein the wafer is held by an edge grip method, and air is blown from the back surface of the wafer. In claim 1,
The driving of the first stage is set at a higher speed than the sampling period for checking the inspection position,
In the process of calculating the timing, when there are a plurality of warp or deflection measurement positions between the current inspection sampling position and the next inspection sampling position, the processor calculates the plurality of warp or deflection measurement positions. A surface inspection apparatus for calculating the second stage drive timing for each of the above. In claim 1,
The driving of the first stage is set to be slower than the sampling period for checking the inspection position,
In the process of calculating the timing, when there are a plurality of inspection sampling positions between two warp or deflection measurement positions, the processor determines a correction determined by the amount of warp or deflection at the two warp or deflection measurement positions. Dividing the amount by the number of samplings between the two warp or deflection measurement positions to calculate a division correction amount, and calculating the second stage drive timing based on the division correction amount. Surface inspection equipment.

Images