JP3334822B2 - Wafer carrier distortion measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer carrier distortion measuring method for automatically measuring the distortion of a wafer carrier used for transferring a semiconductor wafer.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, semiconductor wafers are housed in wafer carriers and are sequentially conveyed through various processes by a robot or the like. As shown in FIG. 4, the wafer carrier used here has a number of vertical grooves (12L, 12L...), (12R, 12L) on the inner surfaces of both side walls 11L, 11R.
R ...), and the wafer is accommodated in pockets formed between the vertical grooves 12L and 12R on both sides.

[0003] The wafer carrier 10 is usually made of plastic such as Teflon or polypropylene, and may be distorted due to robot carrying, stress during formation, or the like. The distortion that is particularly problematic is shown in FIG.
The vertical grooves shown in FIG. 3A, the vertical grooves on both sides shown in FIG. 3B are displaced, and the vertical groove pitches shown in FIG. When these distortions occur, when the wafers W, W... Are transferred by using a wafer holder called a blade, the wafers W, W. , And the wafers W may be damaged. Also, the wafer holder may hit the groove wall and damage the groove wall.

[0004] In order to check such a distortion of the wafer carrier, various distortion measuring devices have been proposed. A conventional distortion measuring device inserts a wafer for inspection into a pocket of a wafer carrier and detects the attitude of the wafer, thereby indirectly measuring the distortion of the wafer carrier and using the wafer for inspection. Instead, the wafer carrier is directly measured using an air micro or the like, and is roughly classified into two types. The inspection wafer used for the indirect measurement is not necessarily a semiconductor wafer, but may be a gauge or the like. Indirect measurement using a gauge is described in, for example, JP-A-2-284014 and JP-A-4-1718.
No. 42 discloses this.

[0005]

When comparing the indirect measurement and the direct measurement, the accuracy of the indirect measurement using the inspection wafer is said to be higher because it is closer to the actual use condition. However, there are the following problems in aspects other than accuracy.

[0006] The wafer rattles in the pockets of the wafer carrier. In the indirect measurement, accurate measurement cannot be performed unless the inspection wafer is fixed in the pocket. Therefore, Japanese Patent Application Laid-Open Nos. Hei 2-284014 and 4-17184
As shown in Japanese Patent Laid-Open Publication No. 2 (1999), the measurement is performed with the opening of the wafer carrier turned sideways so that the inspection wafer in the wafer carrier is horizontal. However, the posture with the opening facing sideways, compared to the natural posture with the opening facing upwards,
Workflow worsens.

In the indirect measurement disclosed in JP-A-2-284014 and JP-A-4-171842, a measurement is performed by inserting one inspection wafer into a pocket of a wafer carrier in order. Therefore, the measurement time is long.

It is an object of the present invention to provide a wafer carrier distortion measuring method capable of solving these problems and indirectly measuring the distortion of a wafer carrier with high accuracy and high efficiency.

[0009]

SUMMARY OF THE INVENTION A wafer carrier distortion measuring method according to the present invention provides a wafer carrier in which an inspection wafer is inserted into all pockets at one time with an opening directed upward and inclined forward or backward. , Move the wafer in the parallel direction,
During the movement, the posture of each inspection wafer in the wafer carrier is sequentially detected.

[0010]

The inspection carrier in the wafer carrier is fixed to one of the groove walls by its own weight by tilting the wafer carrier forward or backward. In this state, by sequentially detecting the posture in the wafer carrier, the distortion of the wafer carrier is accurately and indirectly measured even though the opening of the wafer carrier is turned up and down.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a strain measurement apparatus suitable for carrying out the method of the present invention, and FIG. 2 is a view taken along line AA of FIG.

The wafer carrier 10 is first loaded into the wafer insertion unit 2 on the table 1 with the opening facing upward (). The wafer insertion section 2 is located on one end of the carrier transfer section 3 and is held above for inspection wafers W, W.
Are inserted into all the pockets of the wafer carrier 10 from above by a vertically moving wafer holder called a blade.

After the insertion of the wafers W, W..., The wafer carrier 10 is advanced in the wafer parallel direction by the carrier transfer section 3 and subsequently retreated to the original position (). The transport surface of the carrier transport unit 3 is inclined forward and downward when the wafer carrier 10 is moved forward, and is inclined downward and backward when the wafer carrier 10 is moved backward. Each inclination angle is, for example, 10 to 15 ° with respect to a horizontal plane.

When the wafer carrier 10 moves forward and backward by the carrier transport unit 3, the wafer carrier 10 passes through the measuring unit 4. As shown in FIG. 2, the measuring section 4 has transmission laser sensors 5 and 5 on both sides and an optical displacement sensor 6 at the center. The transmission type laser sensor 5 includes an upper light emitter 5a and a lower light receiver 5b.

When the wafer carrier 10 passes through the measuring section 4, both side portions of the wafers W in the wafer carrier 10 sequentially cross between the light emitting and receiving devices of the transmission laser sensors 5, 5. Thereby, the projection thickness T in the up-down direction of both sides is measured in order. Therefore, FIG.
The fall of the vertical groove shown in (A) is detected. Further, by comparing the data on both sides, the displacement of the vertical grooves on both sides shown in FIG. 3B is detected.

Further, the parallel pitches of the wafers W, W... Are detected by sequentially passing the central portions of the wafers W, W. Therefore, FIG.
The variation in the pitch of the vertical groove shown in FIG. At the same time, the height from the reference level to the top of the wafer is measured in order, and the data shows the lateral deviation and the supporting height of the wafers W, W. Are detected.

In any of the detections, when the wafer carrier 10 moves forward, the wafer carrier 10 is tilted forward. W, W
Is pressed against the front groove wall by its own weight and fixed. Therefore, accurate measurement is performed on wafers W, W.

Further, in this embodiment, the wafer carrier 10
A second measurement is taken during reverse travel. At this time, the wafer carrier 10 tilts backward, and the wafers W, W,... In the wafer carrier 10 are pressed against and fixed to the rear lateral wall. Thereby, more measurements regarding the distortion of the wafer carrier 10 are performed.

After the measurement, the wafer carrier 10 returns to the wafer insertion unit 2, and the wafers W,
After W ... is pulled out upward, it is carried out of the apparatus ().

In the above embodiment, the wafer carrier 10 is tilted forward when the wafer carrier 10 advances, and is tilted backward when the wafer carrier 10 is retracted. .. May be detected only when the wafer carrier 10 moves forward. In this case, the wafer carrier 10 only needs to be tilted to one side.

The inspection wafer W need not be a semiconductor wafer but may be a substitute such as a gauge.

[0022]

As described above, the wafer carrier distortion measuring method of the present invention performs the measurement in a natural posture with the opening of the wafer carrier facing upward, so that the flow is good. Since the wafer carrier is tilted forward or backward, the inspection wafer in the wafer carrier is fixed despite the opening of the wafer carrier being directed upward. Since the measurement is performed by inserting the inspection wafer into all the pockets of the wafer carrier at a time, the measurement time is short. Therefore, highly accurate and highly efficient measurement is possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a strain measurement device suitable for implementing the method of the present invention.

FIG. 2 is a view taken along the line AA of FIG. 1;

FIG. 3 is a schematic diagram showing distortion of a wafer carrier.

FIG. 4 is a perspective view showing a shape of a wafer carrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Table 2 Wafer insertion part 3 Carrier conveyance part 4 Measuring part 5 Transmission laser sensor 6 Optical displacement sensor 10 Wafer carrier W Wafer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-5079 (JP, A) JP-A-2-284014 (JP, A) JP-A-4-171842 (JP, A) JP-A-63- 131533 (JP, A) Hikaru 6-76207 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/68 H01L 21/66

Claims (3)

(57) [Claims] 1. A wafer carrier in which an inspection wafer is inserted into all pockets at one time, is moved in a wafer parallel direction with an opening directed upward and tilted forward or backward. A wafer carrier distortion measuring method, comprising sequentially detecting the posture of each inspection wafer in a carrier. 2. A wafer carrier in which inspection wafers are collectively inserted into all pockets is moved in a wafer parallel direction with an opening directed upward and inclined forward or backward, and then the wafer carrier is turned over. A wafer carrier distortion measuring method characterized by tilting in a direction and moving forward and backward, and sequentially detecting the posture of each inspection wafer in a wafer carrier during each movement. 3. While moving the wafer carrier, the projected thickness in the vertical direction of both sides of each inspection wafer in the wafer carrier is measured in order, and the top level of the central portion of each inspection wafer and the parallel thickness are measured. 3. The method according to claim 1, wherein the pitch is measured in order.