JP3002315B2 - Carrier inspection device - Google Patents

Description

The present invention relates to a carrier for wafer storage used in a semiconductor manufacturing process or a substrate storage carrier used in a CCD manufacturing process or a liquid crystal display panel manufacturing process. The present invention relates to a carrier inspection apparatus used for performing a quality test of a substrate storage carrier to be used.

2. Description of the Related Art Conventionally, a carrier manufacturing factory measures the external shape or the size of the front surface of a slot in which a wafer is to be inserted with a vernier caliper or the like, or inspects the pitch and shape of the slot with a jig to judge the quality. However, sufficient inspection has not been performed due to the labor involved. In semiconductor manufacturing plants, no specific inspection was performed, and carriers deformed by heat treatment or the like were used as they were. For this reason, a mistake in taking out the wafer stored in the carrier or a mistake in storing the processed wafer may occur, causing a process delay, and reducing the productivity. In particular, recently, as the degree of integration of semiconductors has increased, it has been necessary to minimize the attachment of foreign substances to wafers, and robot hands have been frequently used as a method of taking out wafers from a carrier or storing wafers in a carrier. . Therefore, if a deformed carrier or a carrier having poor dimensional accuracy is used, erroneous removal or storage of a wafer is likely to occur, and quality control of the carrier is required not only in a carrier manufacturing plant but also in a semiconductor manufacturing plant.

[Problem to be Solved by the Invention] The present invention is based on the premise that a wafer is taken out or stored by a robot hand.
It is an object of the present invention to provide an inspection apparatus for easily measuring the dimensional accuracy required of a carrier, setting a clear reference value, and testing the quality. As a result, not only a carrier manufacturing plant but also a semiconductor manufacturing plant can extract a deteriorated carrier that has been deformed in a short time and select and use only a good carrier, thereby contributing to an improvement in productivity.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides at least two transmission lasers in which a reference wafer is housed in all wafer slots of a carrier to be measured and placed on a reference plane. A sensor is placed symmetrically to the reference wafer center line and parallel to the reference plane, and at least one reflective laser sensor is placed at the center of the transmission laser sensor and parallel to the reference plane. By driving the reference plane up and down, the back surface heights of all the reference wafers from the reference plane are measured. From these measurement data, the height dimension of the wafer slot or the inclination due to distortion can be calculated indirectly by mathematical calculation. Since the measurement uses a laser sensor, it can be performed without contacting the reference wafer or the carrier, so that the measurement can be performed accurately without deforming the carrier itself.

[Operation] In the case of one reference wafer, the back surface height from the reference plane at four circumferential portions of the wafer can be calculated by two transmission laser sensors. One type of reflection type laser sensor is used to determine in which direction the wafer is tilted in the carrier to be measured. From the back surface height data, a maximum height dimension, a minimum height dimension, or a maximum height position of the wafer from the reference plane can be calculated by a mathematical plane equation. By measuring all the wafers stored in the carrier to be measured in this way, the maximum height dimension or the maximum height position can be measured for all the wafer slots of the carrier to be measured. In addition, if the dimensions of all wafer slots are registered in the computer and limit values are set,
The pass / fail of the measured carrier can be automatically verified by automatically comparing the measured data with the measured data. FIG. 4 shows a circular wafer 10A.
Of up to the back surface of the circumferential portion and the transmission type laser sensor optical axis 11A reference plane intersection _{P 2} and _{P 3} of the height _{H P2, H P3}
And Intersection _{P 4} and P of the transmission type laser sensor optical axis 11B
From ₅ reference plane to the back surface height and _{H P4, H P5.} The X, Y, and Z orthogonal coordinate systems for the carrier 9 to be measured and the circular wafer 10A are used to determine the center P of the circular wafer 10A.
_The carrier to be measured 9 so that ₀ is the origin of the X axis and the Y axis.
Is placed. Linear _P 2 _{P 4} of the middle point _{P 6} and the middle point _{P 7} linear _P 3 _{P 5} is located on the Y axis. It said circular wafer 10A height of the rear surface of the P ₆ and _{P 7} each and _{H P6, H P7.} The distance of the straight line P ₂ P ₄ is X ₀ , and the distance of the straight line P ₆ P ₇ is Y ₀ . Also, the distance between the straight line P ₆ P ₀ is Y ₁ and the straight line P ₀
The distance P ₇ and _{Y 2.} X ₀ , Y ₀ , Y ₁ , and Y ₂ can all be calculated as known numerical values if the diameter of the circular wafer 10A is known. When viewed from the front, the left side of the measured carrier 9 is defined as the positive direction of the X axis, the depth direction is defined as the positive direction of the Y axis, and the area above the reference plane is defined as the positive direction of the Z axis. The height H _P0 of the center P ₀ on the back side of the circular wafer 10A, the height H _MAX at the maximum height position C of the circumferential portion, and the minimum height position D.
The maximum height H _MIN and the angle θ _MAX of the direction at the maximum height position C of the circumferential portion in the counterclockwise direction with respect to the center P ₀ from the positive X-axis direction are as follows: Desired.
Inclination J in the X direction of the circular wafer 10A, inclination K in the Y direction, when the height of the center P ₀ of the N hold the following plane equation.

JX + KY + Z + N = 0 J = (H P4 -H P2) ÷ X 0 K = (H P7 -H P6) ÷ Y 0 _{However, H P7 = (H P3 +} H P5) ÷ 2 H P6 = (H P2 + H P4) ÷ 2 N = H _P0 = H _P6 + (H _P7 −H _P6 ) × (Y ₁ ÷ Y ₀ ) The direction θ _MAX of the maximum height position from the signs of J and K is 0 ≦ θ ≦ 90 °, if J ≧ 0 and K ≧ 0, θ _MAX = θ J <0 and K ≧ 0, θ _MAX = 180−θ If J <0 and K <0, θ _MAX = 180 + θ If J ≧ 0 and K <0, θ _MAX = 360−θ Maximum height position height H _MAX , Minimum height position height H _MIN
Is calculated as follows, where M is the radius of the circular wafer.

H _MAX = J × M × COSθ _MAX + K × M × SINθ
_MAX + N H _MIN = −J × M × COS θ _MAX− K × M × SIN
be performed for all of the circular wafer 10 a theta _{MAX +} N above calculation, it is possible to make the comparison with the reference value size is the design dimensions of the entire wafer slots.

[Embodiment] As shown in FIG. 1, a carrier base 1 serving as a reference plane has circular wafers 1 with no notches for reference.
0 is placed in each wafer slot, and the transmission type laser sensor light-receiving unit 3A and the light-emitting unit 4A are arranged so that the optical axes 11A, 11B, and 11C are parallel to the reference plane. The height from the reference plane to each of the circular wafers 10 is measured by three laser sensors including a laser sensor light receiving unit 3B, a light emitting unit 4B, and a reflection type laser sensor 5. Slits 6A, 6B, 7A and 7B for narrowing down the laser beam are provided in front of the light emitting portion and the light receiving portion of the transmission type laser sensor in order to increase the measurement accuracy. These laser sensors and slits are fixed to the fixed base 2. In order to fix the measured carrier 9 at a predetermined position, the carrier base 1 is provided with carrier position determining frames 12A, 12B and 12C. The carrier base 1 is driven in a direction perpendicular to the reference plane. FIG. 2 schematically shows a side view of the measurement system. When the carrier base 1 is driven in the direction of the arrow, each circular wafer 10 in the carrier 9 to be measured is transmitted through the transmission laser sensor 3A,
Optical axis 11A of 4A and transmission type laser sensor 3 of another system
The optical axes 11B of B and 4B are cut off. If the light blocking or light transmission of these laser sensors is detected, the amount of movement of the carrier base 1 is known, so that the height from the front surface of the carrier base 1 as the reference plane to the back surface and the front surface of each circular wafer 10 can be measured. Carrier base 1 to increase accuracy
Is measured and averaged back and forth as indicated by the arrow. However, as shown in FIG. 2, among the circular wafers 10 in the carrier 9 to be measured, the circular wafer 10 tilted with respect to the reference plane.
Since A is measured as a projected cross section as shown in FIG. 3, the height H from the reference plane to the back surface of the circular wafer 10A is measured.
1 and the height H2 from the surface to the surface
It becomes larger than the thickness T of A. As shown in FIG. 4, P ₂ ,
From the reference plane at P ₃ , P ₄ , P ₅ , the circular wafer 10
Since it is necessary to measure the height to the back side of A, whether the back side B of the wafer slot of the carrier 9 to be measured is low or the front side A
Needs to be detected as low. In FIG. 1, the reflection type laser sensor 5 is used to measure the height of the back surface of each circular wafer 10 at the front position on the front side of the wafer slot in order to determine whether the back side or the front side of the wafer slot is low. . As can be seen in FIG.
The height of the back surface of the circular wafer 10A measured by
And Each circular wafer 10 including the circular wafer 10A
Since the thickness T is uniform and known, the following relationship is established. If H3> H1 and H3 ≒ H2-T, the back side of the wafer slot is low, and if _HP2 = H2- _THP3 = H1 and if H3 ≒ H1 and H3 <H2-T, the front side of the wafer slot is low and _HP2 = H1. H _P3 = H2-T Similarly _{P 4} and _P to the rear surface of a ₅ height _{H P4} and _{H P5} can also be measured. As shown in FIG. 2, in the measurement of the reference plane, the surface of the carrier base 1 is not directly detected in order to improve the accuracy, but the reference plane detecting wafer piece fixed at a known height from the surface of the carrier base 1 is used. 8 is calculated by detecting the height of the back surface by the reflection type laser sensor 5.

Other Embodiments In the present invention, a laser sensor is used as a method for measuring the height of a reference circular wafer stored in a carrier to be measured, but a CCD image sensor may be used. As a method of measuring all the reference wafers, the carrier to be measured moves up and down. Alternatively, the laser sensor may move. The reference wafer can be measured by partially inserting the wafer into the entire wafer slot instead of the entire wafer slot. In the above embodiment, the carrier for storing a circular wafer is described. However, the measurement of the carrier for storing a square substrate for manufacturing a liquid crystal display can be realized in a similar manner.

Effect of the Invention According to the present invention, the quality of a carrier, which has conventionally been left to the sensory judgment of the inspector, can be judged with an objective numerical limit. Conventionally, the inspection is troublesome, and the inspection is performed by sampling. However, since the inspection can be performed in a short time, the entire inspection can be performed. Further, since a common inspection standard can be established between the carrier manufacturer and the carrier user, defective carriers can be promptly returned at the time of acceptance inspection at the carrier user. Manufacturers can now measure the dimensions of the inside of a carrier's wafer slot, so the data of the manufactured carrier can be fed back to the design to help improve quality. Since semiconductor manufacturers on the carrier user side can use only good carriers,
This has made it possible to reduce equipment troubles and improve productivity.

[Brief description of the drawings]

FIG. 1 is a plan view of a measurement unit of a carrier inspection device. Second
The figure is a diagram schematically illustrating a side view of the carrier inspection device measurement unit. FIG. 3 is a diagram for explaining the relationship between heights measured by three types of laser sensors. FIG. 4 is a plan view of a circular wafer to be measured. 10A 'in the figure is 10
Circular wafer is inclined contrary to the A, R is the right direction as viewed from the front, L is the left direction, P ₁ is the position of the circular wafer that is measured by the reflection-type laser sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H01L 21/68 H01L 21/68 F (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 19/00 B65H 7 / 14 G01B 11/00 G01B 11/02 G01B 21/22 H01L 21/68

Claims (3)

(57) [Claims] A carrier for accommodating a plurality of plate-like objects at a distance from each other; a carrier base for placing the carrier; a first transmission laser sensor and a second transmission laser sensor; A transmission-type laser sensor provided in parallel with a reference plane that is a surface of the carrier base; a driving unit that drives the carrier or the transmission-type laser sensor in a direction perpendicular to the reference plane; Thereby, when the carrier or the transmission type laser sensor is driven in a direction perpendicular to the reference plane, the plate-like object traverses a laser passage area of the transmission type laser sensor, and from the reference surface, The height of the front and back surfaces of the plate (the laser beam moves from bottom to top)
The height at which the laser beam began to cross the back of the plate
Carrier inspection means for inspecting the quality of the carrier by measuring the height of the carrier and the height at which the laser beam has traversed the surface of the plate-like object . 2. The device according to claim 1, wherein the first transmission type laser sensor and the second transmission type laser sensor are provided substantially symmetrically with respect to the center of the plate-like object. Carrier inspection equipment. 3. The carrier inspection apparatus according to claim 1, further comprising a reflection-type laser sensor that detects reflection from an edge surface of the plate-like object.