SHAPE MEASUREMENT APPARATUS AND SHAPE MEASUREMENT METHOD

• US 20100134615A1
• Filed: 07/18/2008
• Published: 06/03/2010
• Est. Priority Date: 07/18/2007
• Status: Active Grant

• Current Assignee: Kobelco Research Institute Incorporated (Kobe Steel Limited)
• Original Assignee: Kobelco Research Institute Incorporated (Kobe Steel Limited)
• Inventors: Hashizume, Hidehisa, Nakai, Yasuhide, Akamatsu, Masaru
• Granted Patent: US 8,310,536 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• CPC Class Codes: G01B 11/2433 for measuring outlines by shadow casting
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/9503 Wafer edge inspection

Abstract

To provide a shape measurement apparatus and a shape measurement method with which it is possible to perform a shape measurement, when a shape of an end surface of a disk-shaped semiconductor wafer or the like is measured on the basis of a projection image thereof, without receiving an influence of a contaminant on the end surface.

With a rotation supporting mechanism 9 supporting a wafer 1, the wafer 1 is supported in a range from a first supporting position rotated by +δ with respect to a predetermined reference supporting position to a second supporting position rotated by −δ degrees at two or more supporting positions including the first supporting position and the second supporting position, a projection image of the end surface of the wafer 1 supported at the respective supporting positions is picked up by an image sensor 7, an index value of an end surface value is calculated for each of a plurality of obtained projection images, a selection of one representative value based on the plurality of calculated index values or a calculation of one aggregate value is performed, and a measurement value for the shape of the end surface of the wafer 1 corresponding to the reference supporting position is derived. At that time, when a radius of the wafer 1 and a chamfer width are set as r and k, δ≧cos⁻¹ ((r−k)/r) is desirably satisfied.

Claims

1. A shape measurement apparatus comprising:

light transmission means configured to transmit light to a chamfer processed end part of a disk-shaped measurement target from a direction substantially parallel to respective front and rear surfaces of the measurement target;

image pickup means configured to pick up a projection image of an end surface of the measurement target from a direction opposite to the light transmitting direction;

a rotation supporting mechanism configured to rotatably support the measurement target in a circumferential direction thereof;

rotation control means configured to support the measurement target by the rotation supporting mechanism in a range from a first supporting position rotated by a predetermined first set angle with respect to a predetermined reference supporting position to a second supporting position rotated by a predetermined second set angle having an opposite positive or negative sign with respect to the first set angle at two or more supporting positions including the first supporting position and the second supporting position;

image pickup control means configured to pick up by the image pickup means the projection image of the end surface of the measurement target supported by the rotation control means at the two or more supporting positions;

index value calculation means configured to calculate an index value of an end surface shape by executing a previously set image processing for each of a plurality of projection images obtained through a processing by the image pickup control means; and

measurement value derivation means configured to derivate a measurement value for the shape of the end surface of the measurement target corresponding to the reference supporting position by selecting one representative value based on the plurality of index values calculated by the index value calculation means or calculating one aggregate value while following a previously set rule.

2. The shape measurement apparatus according to claim 1, wherein:

the rotation control means supports the measurement target by the rotation supporting mechanism at three or more supporting positions including the reference supporting position, the first supporting position, and the second supporting position; and

the image pickup control means picks up by the image pickup means the projection image of the end surface of the measurement target supported at each of the three or more supporting positions by the rotation control means.

3. The shape measurement apparatus according to claim 1, wherein the previously set rule is any of a rule of selecting a median value, a smallest value, or a largest value among the plurality of the index values and a rule of calculating an average value for a previously set numbers of values in an order from a smaller one or a larger one among the plurality of index values.

4. The shape measurement apparatus according to claim 1, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 satisfy the following expression (a1);

δ

1≧

cos<sup>−

1</sup>((r−

k)/r)

δ

2≧

cos<sup>−

1</sup>((r−

k)/r)  

 

(a1)

r;

Radius of the measurement target

k;

Chamfer width of the end surface of the measurement target.

5. The shape measurement apparatus according to claim 1, wherein the measurement target is a semiconductor wafer.

6. The shape measurement apparatus according to claim 5, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 satisfy the following expression (a2);

22.5≧

δ

1≧

cos<sup>−

1</sup>((r−

k)/r)

22.5≧

δ

2≧

cos<sup>−

1</sup>((r−

k)/r)  

 

(a2)

r;

Radius of the semiconductor wafer

k;

Chamfer width of the end surface of the semiconductor wafer where, k/r<

0.076.

7. The shape measurement apparatus according to claim 5, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 are respectively in a range between 2°

or larger and 22.5°

or smaller.

8. The shape measurement apparatus according to claim 1, wherein the index value is any one of the chamfer width of the measurement target, a chamfer angle, and a chamfer radius.

9. A shape measurement method comprising:

transmitting light by light transmission means to a chamfer processed end part of a disk-shaped measurement target from a direction substantially parallel to respective front and rear surfaces of the measurement target;

picking up a projection image of an end surface of the measurement target by image pickup means from a direction opposite to the light transmitting direction;

supporting the measurement target by a rotation supporting mechanism rotatably supporting the measurement target in a circumferential direction thereof in a range from a first supporting position rotated by a predetermined first set angle with respect to a predetermined reference supporting position to a second supporting position rotated by a predetermined second set angle having an opposite positive or negative sign with respect to the first set angle at two or more supporting positions including the first supporting position and the second supporting position;

picking up by the image pickup means a plurality of projection images of the end surface of the measurement target supported at the respective supporting positions;

recording image pickup data in predetermined storage means;

calculating a plurality of index values of an end surface shape by executing a previously set image processing by predetermined computation means for each of the plurality of projection images; and

executing a processing of deriving a measurement value for the shape of the end surface of the measurement target corresponding to the reference supporting position by predetermined computation means by selecting one representative value based on the plurality of index values calculated by the index value calculation means or calculating one aggregate value while following a previously set rule.

10. The shape measurement method according to claim 9, wherein the measurement target is supported by the rotation supporting mechanism at three or more supporting positions including the reference supporting position, the first supporting position, and the second supporting position, and the projection image of the end surface of the measurement target supported at each of the three or more supporting positions is picked up by the image pickup means.

11. The shape measurement method according to claim 9, wherein the previously set rule is any of a rule of selecting a median value, a smallest value, or a largest value among the plurality of the index values and a rule of calculating an average value for a previously set numbers of values in an order from a smaller one or a larger one among the plurality of index values.

12. The shape measurement method according to claim 9, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 satisfy the following expression (a1);

δ

1≧

cos<sup>−

1</sup>((r−

k)/r)

δ

2≧

cos<sup>−

1</sup>((r−

k)/r)  

 

(a1)

r;

Radius of the measurement target

k;

Chamfer width of the end surface of the measurement target.

13. The shape measurement method according to claim 9, wherein the measurement target is a semiconductor wafer.

14. The shape measurement method according to claim 13, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 satisfy the following expression (a2)

22.5≧

δ

1≧

cos<sup>−

1</sup>((r−

k)/r)

22.5≧

δ

2≧

cos<sup>−

1</sup>((r−

k)/r) tm (a2)

r;

Radius of the semiconductor wafer

k;

Chamfer width of the end surface of the semiconductor wafer where, k/r<

0.076.

15. The shape measurement method according to claim 13, wherein in a case where the first set angle is denoted by +δ

1 and the second set angle is denoted by −

δ

2, the δ

1 and the δ

2 are respectively in a range between 2°

or larger and 22.5°

or smaller.

16. The shape measurement method according to claim 9, wherein the index value is any one of the chamfer width of the measurement target, a chamfer angle, and a chamfer radius.