JPH02116143A - Square device aligner - Google Patents

Abstract

PURPOSE:To facilitate alignment in a short time by a method wherein, when a square device is rotated, a light which is transmitted from a light emission source without being interfered by the square device is detected by a photodetector and four peak level values are obtained in one rotation and a discrepancy of the alignment is calculated from the values. CONSTITUTION:A ceramic square substrate 10 is attracted by a subchuck 12. When the discrepancy of the substrate 10 is detected, the substrate 10 is rotated by a subchuck Z-direction driving means 13, a subchuck rotating driving means 14, tweezers X-direction driving means 16 and a Y-axial direction driving means 17. A light emitting diode 18 whose emitting light is interfered on the diagonal of the substrate 10 and transmitted if the facing sides are in parallel with each other is provided near the circumference of the substrate 10 and a photodetector 19 is provided so as to face the light emitting diode 18. Thus small and big four level values are detected every one turn of the substrate by a light detecting level detecting means 22 and the difference in level is processed by a CPU 30 having built-in discrepancy calculating means 33 and comparing means 31 and each driving means is controlled so as to eliminated the difference.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a positioning device for a rectangular body.

[Conventional technology]

Conventionally, there is an inspection apparatus called a 10-bar which inspects a circular semiconductor wafer as shown in FIG. In this inspection apparatus, it is necessary to align the semiconductor wafer to a predetermined position on the substrate mounting table for inspection. This alignment includes coarse alignment and fine alignment. Rough alignment is called prealignment. First, a semiconductor wafer 1 is pulled out of a substrate storage unit called a cassette and placed on a substrate mounting table called a sub-chuck, where pre-alignment is performed.Next, the semiconductor wafer 1 that has been pre-aligned is called a main chuck. The substrate is transferred from the sub-chuck to the substrate mounting table. Fine positioning is then performed on this main chuck to ensure accurate positioning and inspection. Pre-alignment is performed by aligning the center position of the semiconductor wafer 1 with the center position l of the sub-chuck, and also aligning the center position of the semiconductor wafer 1 with the center position l of the sub-chuck, and aligning the center position of the semiconductor wafer 1 with the orientation flat 2 provided in a part of the semiconductor wafer 1 as shown in FIG. A process is performed to determine the direction of the semiconductor wafer 1 based on the . Conventionally, pre-alignment is carried out at the peripheral edge of the semiconductor wafer 1, as shown in FIG.
A light source consisting of a light emitting diode and a light receiving element are provided at positions sandwiching the light emitting diode. In other words, when the semiconductor wafer 1 is rotated, the area where the wafer blocks light changes depending on the positional shift of the semiconductor wafer on the sub-chuck. It detects the position and performs pre-alignment.

[The problem that the invention tries to solve! l! ]

By the way, opaque rectangular substrates made of ceramic, for example, have recently come into use, but these rectangular substrates also require a process to be inspected with an inspection device, and for that inspection, alignment and fine positioning are required. is necessary. However, unlike a semiconductor wafer, this opaque rectangular substrate is rectangular, so the technique of glial alignment for a circular semiconductor wafer cannot be used as is. The present invention aims to provide an alignment device that improves the above-mentioned drawbacks.

[Means to solve the problem]

The positioning device according to the present invention detects the amount of positional deviation from the intersection of the locus of the rectangular substrate mounting body when it is rotated and a predetermined reference point, and adjusts the amount of positional deviation as described above so that the amount of positional deviation becomes zero. A means for correcting the position of the object to be aligned is provided.

[Effect]

Since the rectangular object is rotated and compared with a predetermined reference, alignment can be performed while assuming that the object to be aligned is substantially circular.

【Example】

An embodiment of the rectangular object positioning apparatus according to the present invention will be described below with reference to the drawings. Of the light from the light emitting source, the light corresponding to the area blocked by the rectangular substrate is received by the light receiving element. When the rectangular substrate is rotated, the irradiation position of the light from the light emitting source will draw a circular trajectory on the rectangular substrate.In other words, it will draw an inscribed circle on the rectangular substrate as shown in Figure 2. It can be seen that the light receiving output is maximum at that contact position. From this, if the detection means detects the four points at which the received light output is maximum, the position of the rectangular glass substrate on the substrate mounting table can be determined and alignment can be performed. By the way, when finding the four points where the received light level is maximum, it is difficult to set the threshold value due to variations in light intensity if you try to find the positions where the received light output exceeds a certain value. Therefore, in this example, conversely, the position where the received light level is low is first detected, and the peak value of the received light level is detected based on this. This is because a position where the received light level is at its peak always exists next to a position where the received light level is low. This is because the variation when the light reception level is low is small, and the threshold value can be easily set. In FIG. 1, 10 is a rectangular ceramic substrate as shown in FIG. 2, for example. 12 is a sub-chuck on which the ceramic rectangular substrate 10 is placed. This sub-chuck 12 can be driven in the vertical direction by a sub-chuck Z-axis direction driving means 13. Further, the ceramic rectangular substrate 10 that is attracted to the sub-chuck 12 is rotated in the direction of the plate surface by the sub-chuck rotation driving means 14. Further, 15 is a moving table called tweezers. The tweezers 15 act as a robot to pull out the ceramic rectangular substrate from the cassette and bring the ceramic rectangular substrate onto the sub-chuck 12. Therefore, the tweezers 15 are moved in the left and right directions indicated by arrows in the figure by the tweezers X-direction driving means 16, and
It is adapted to be moved by an axial drive means 17 in a direction perpendicular to the plane of the paper. The ceramic rectangular substrate 10 brought onto the sub-chuck by the tweezers 15 is
The sub-chuck 12 is lifted upward by the Z-axis driving means 13, and thereby transferred from the tweezers 15 onto the sub-chuck 12, resulting in the state shown in the figure. For example, a light emitting diode 18 as a light source is provided in a portion located below the peripheral portion of the ceramic rectangular substrate 10 . At a position facing the light emitting diode 18 above the periphery of the ceramic rectangular substrate 10,
A light receiving element 19 is provided. Therefore, the light emitting diode 18 and the light receiving element 19 are mounted on the ceramic rectangular substrate 1.
It is provided so as to sandwich 0. In this case, as shown in FIG. 2, an inscribed circle is drawn on the ceramic rectangular substrate 10, and the contact points are A and B. C and D, when the ceramic rectangular substrate 10 is rotated assuming that the center position of the ceramic rectangular substrate 10 (center of gravity) and the center position of the sub-chuck 12 match, the above contact point A , B, C, and D, the installation positions of the light emitting diode 18 and the light receiving element 19 are such that a part of the luminous flux 24 from the light emitting diode 18 is supplied to the light receiving element 19 via the ceramic rectangular substrate 10. is determined. Note that in order to cope with changes in the size of the ceramic rectangular substrate 10 that is the object to be inspected, light emitting diodes 20 and 21 are installed in the radial extension direction of the sub chuck 12 in the pond of the light emitting diode 18. It is provided. The output of the light receiving element 19 is supplied to the light receiving level detection means 22. In this case, the light receiving element 19 receives the transmitted light after subtracting the irradiation area of the light from the light emitting diode 18 on the ceramic rectangular substrate 10. A level output signal is obtained. The output signal of the level detection means 22 is supplied to an A-D converter 23 and digitized. and,
Digital data of q is supplied to the CPU 30. This C
The PU 30 includes a comparison means 31 for detecting a point where the signal SD is below a threshold value, a detection means 32 for detecting four peak level values based on the output of the comparison means 31, and a position deviation calculation means. 33 and each driving means 13,1
Reference numeral 40 is a key power board which has the function of the drive signal forming means 34 for 4° 16. One realignment of a rectangular ceramic substrate using this alignment device will be described below. In the following explanation, for simplicity, the ceramic rectangular substrate 1
It is assumed that the reference plane direction of 0 is predetermined by the operator. The ceramic rectangular substrate 10 adsorbed onto the sub-chuck 12 is rotated by the sub-chuck rotation driving means 14 rotating the re-sub chuck 12 . Then, the detection output SD from the received light level detection means 22 is
As shown in FIG. 3, the intersection points E, F, and GH when perpendicular lines are drawn from the rotation center Os (offset from the center Og of the ceramic rectangular substrate 10) to each side of the ceramic rectangular substrate 10 It reaches a peak at the rotational angular position of each 90 degree angular interval where the light is irradiated, and reaches a minimum level at each corner of the rectangular substrate 10. Therefore, as shown in FIG. 4, the detection output SD from the received light level detection means 22 has four peaks each in the direction of the large level and four peaks in the direction of the small level during one rotation. If the position of the ceramic rectangular substrate 10 on the sub-chuck 12 is significantly deviated, the ceramic rectangular substrate 10 is placed on the sub-chuck 12 again.For example, if the locus of the light irradiation position is Rectangular shaped substrate 10
On the other hand, when the dotted line 50 in FIG.
By moving 0, four small level peaks can appear. When the received light output reaches a state where four peaks are obtained, the digital value of the output SD from the A-D converter 23 and the small level threshold ff1TH as shown in FIG. Comparing means 31 compares the peak existence positions SE, SF, SG, SH in the direction of the small level.
is detected first. Next, the detected peak value fsE in the direction of the small level, SF
, SG, SH, the peak value in the direction of the large level that appears after this! The digital values of the output SD are searched until the peak values PE, PF, PG, and PH in the direction of the large level are determined by the so-called hill-climbing method. Then, each peak level value PE, PF, PG,
The amount of positional deviation is determined by the calculation means 33 based on the PH. In this case, in FIG. 3, if the amount of deviation of the center position Og of the ceramic rectangular substrate 10 from the center position O5 of the sub-chuck 12 in the FH force direction is X, and the amount of deviation in the EG force direction is Y, then the peak level value The level difference between PF and PH corresponds to the amount of deviation X, and the level difference between the peak level values PE and PG corresponds to the amount of deviation Y. The light receiving element 19 has a certain length, and the light receiving output level corresponds to the length of the incident light irradiating the light receiving element 19, so the light receiving output level when the incident light is incident on the entire length is used as a reference. Then, the received light output level can be converted into length. In the deviation amount calculating means 33,
In this way, the deviation amounts X and Y converted into lengths are determined. Furthermore, since tanθ=Y/X, the deviation angle θ can be determined. Furthermore, the distance [D] between O5 and 08 can also be found from X and Y. These angle θ and distance information are transmitted to the drive signal forming means 34
, the information is converted into rotational drive information for the sub-chuck 12 and tweezers X-direction drive information, and these drive information are supplied to the sub-chuck drive means 14 and the tweezers X-direction drive means 16, respectively. In FIG. 3, a ceramic rectangular substrate 10
is rotated by an angle θ in the counterclockwise rotation direction so that the center Og of the ceramic rectangular substrate 10 is on the straight line FH.
13, the ceramic rectangular substrate 10 is placed on the tweezers 15, and then the tweezers 15 are moved to the right by a distance. This position is a position where the centers O5 and Og coincide. In this state, the sub chuck 12 rises upward again, and the sub chuck 12
A ceramic rectangular substrate 10 is placed thereon. Then, the sub-chuck 12 is now rotated by an angle θ in the clockwise rotation direction, thereby aligning the ceramic rectangular substrate 10 to the correct position. The method of correcting positional deviation using the peak level values at the four points E, F, G, and H is not limited to the above example. For example, the tweezers can be moved in the X and Y directions. If it is possible, there is no need to find the angle of deviation θ. Although the above description is for the case where the rectangular body is a ceramic rectangular substrate, the present invention can be applied to alignment of various opaque rectangular substrates. [Effects of the Invention] According to the present invention, when the rectangular body is rotated, the light that appears in the light receiving output of the light receiving element that receives the light transmitted from the light emitting source without being blocked by the rectangular body within one rotation. It is possible to detect the four peak level values of , and calculate the amount of positional deviation using the detected four peak level values. Therefore, alignment of the rectangular bodies can be performed in a relatively short time. Moreover, in the example shown in the figure, it is important to note that when the rectangular body is rotated, the received light output level appears alternately at a small level and a large level, and the small level peak is determined by the threshold value for detection. Focusing on the ease of setting, we first found the small level peak and then detected the peak level value in the direction of the large level, so we can reliably detect the four peak level values in the direction of the large level. be able to.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an example of the present invention, and FIG. 2 is a diagram showing the configuration of an example of the present invention.
A diagram showing an example of a ceramic rectangular substrate, FIG. 3 is a diagram for explaining the positional deviation between the center of the ceramic rectangular substrate and the center of the sub-chuck, and FIG. 4 is an example of the received light output. 5 are diagrams for explaining the calculation of the amount of positional deviation, and FIGS. 6 and 7 are diagrams for explaining the alignment of the semiconductor wafer. 10; Ceramic rectangular substrate 12; Sub chuck 14; Sub chuck rotation drive means 16; Tweezers X direction drive means 18; Light emitting diode 19: Light receiving element 22; Received light level detection means 31; Small level peak detection means 33; Amount of deviation Calculating means patent applicant Tokyo Electron Co., Ltd. agent Patent attorney Tadashi Sato Miyu Output SO-2 warp Figure 4 Place A IrfLlzutL l 'Ft 7rX4 Figure 3 Semiconductor wafer Figure 6 and a half 11 production tawny An position Ytlich installation. Figure 7

Claims (1)

[Claims] The amount of positional deviation is detected from the intersection of the trajectory of the rectangular alignment body when it is rotated and a predetermined reference point, and the position of the object to be aligned is corrected so that the amount of positional deviation becomes zero. A rectangular object positioning device comprising: means.