JPWO2010073817A1 - Substrate positioning apparatus, substrate processing apparatus, substrate positioning program, and electronic device manufacturing method - Google Patents

Abstract

The present invention improves the detection accuracy of misalignment in a substrate positioning apparatus having a purpose of correcting misalignment of a substrate being conveyed in a semiconductor / electronic component manufacturing apparatus. In one embodiment of the present invention, the waveform measured by the light shielding sensor is first approximated by a sin curve, and the maximum value of the deviation and the position of the deviation are obtained from the approximate expression.

Description

  The present invention relates to a substrate positioning apparatus and positioning method in a manufacturing apparatus for electronic components such as semiconductors and magnetoresistive elements.

  Conventionally, the following method disclosed in Patent Document 1 is known as a method for detecting a positional deviation of a substrate in an apparatus for manufacturing an electronic component such as a semiconductor or a magnetoresistive element.

  In Patent Document 1, the stage is rotated with the substrate placed on the stage, the position of the outer periphery of the rotating substrate is measured with a light-shielding sensor fixed to the outer periphery of the stage, and the substrate is based on the waveform based on the measured value. Detects the position shift.

JP-A-8-8328

  However, since the resolution of the light shielding sensor is constant, if the amount of positional deviation of the substrate is reduced, the change in the light shielding amount of the sensor is reduced and the change in the waveform is also reduced. There is a problem that it is difficult to find a portion where the light shielding amount is maximum when the change in the waveform is small.

  The present invention has been made in view of the above-described problems. A substrate positioning apparatus, a substrate processing apparatus, a substrate positioning program, and an electronic device that can estimate the positional deviation amount with high accuracy even when the positional deviation amount of the substrate is small. The object is to provide a manufacturing method.

  A first aspect of the present invention is a substrate positioning apparatus, comprising: a substrate holding means for holding a substrate; and a virtual center in a holding surface of the substrate when the substrate is held by the substrate holding means. A distance measuring unit that measures an in-plane direction distance to the substrate end, a line segment that connects the virtual center and a reference point of the substrate end, and a measurement in which the in-plane direction distance is measured by the distance measuring unit An angle acquisition unit that measures an angle formed by a line segment that connects a location and the virtual center, an in-plane direction distance measured by the distance measurement unit, and an angle measured by the angle acquisition unit, Measurement waveform acquisition means for acquiring a measurement waveform corresponding to an inward distance and the angle, approximation means for approximating the measurement waveform to a trigonometric function, and the trigonometric function approximated by the approximation means. Group Characterized in that it comprises a calculating means for calculating a deviation amount from the virtual center of.

  According to a second aspect of the present invention, there is provided a substrate positioning program, which is a line connecting an in-plane direction distance from a virtual center to a substrate end in a substrate holding surface, and the virtual center and a reference point of the substrate end. A measurement waveform acquisition step for acquiring a measurement waveform in which a minute and an angle formed by a line segment connecting the measurement location where the in-plane direction distance is measured and the virtual center are matched, and the measurement waveform is a trigonometric function And an arithmetic step for calculating a deviation amount of the center of the substrate held on the holding surface from the virtual center based on the trigonometric function approximated in the approximating step. And

  According to a third aspect of the present invention, there is provided a substrate processing apparatus, the substrate positioning apparatus according to the first aspect, a transfer chamber including a transfer robot for transferring the substrate, and connected to the transfer chamber. The substrate is configured to be capable of transporting a substrate by the transport robot, and includes a process chamber for processing the transported substrate.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing an electronic device, wherein the electronic device is manufactured using the substrate processing apparatus according to the third aspect.

  By using the values obtained in the present invention, the wafer positioning accuracy can be improved.

1 is a schematic plan view of a substrate processing apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of an alignment chamber according to an embodiment of the present invention. It is a top view which shows the positional relationship of the light-shielding sensor and substrate stage based on one Embodiment of this invention. It is a figure which shows the board | substrate positioning flow which concerns on one Embodiment of this invention. It is a graph which shows the measurement waveform which concerns on one Embodiment of this invention. It is a graph which shows the outline of the maximum shift angle detection by sin curve approximation based on one Embodiment of this invention. It is a top view which shows the relationship between the position shift of a board | substrate and the position of a substrate stage based on one Embodiment of this invention. It is a figure which shows the light-shielding sensor measured value waveform based on one Embodiment of this invention, and the waveform approximated by the sin curve from the measured value. It is a figure which shows the light-shielding sensor measured value waveform when deviation | shift amount is small based on one Embodiment of this invention. It is a figure which shows the dispersion | variation in the precision before and after application of one Embodiment of this invention when the angle of a largest deviation position is detected continuously when a wafer is a fixed deviation | shift amount. It is a figure which shows the dispersion | variation in the precision before and after application of one Embodiment of this invention when the angle of a largest deviation position is detected continuously when a wafer is a fixed deviation | shift amount.

  Next, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

FIG. 1 is a diagram showing a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention.
The substrate processing apparatus shown in FIG. 1 is provided with a transfer robot 4 for transferring a substrate, an alignment chamber 1 as a substrate positioning device, a transfer chamber 2 having a plurality of chambers for processing a substrate, and a transfer chamber. 2 and a plurality of process chambers 3 for performing processing on the substrate.

  The substrate is sequentially transferred to each of the plurality of process chambers 3 by the transfer robot 4, and processing in each process chamber 3 is performed.

  The plurality of chambers included in the process chamber 3 include a film formation chamber for performing film formation processing on the substrate by sputtering or CVD, a chamber for performing temperature adjustment, degassing, and cleaning such as heating and cooling of the substrate, and etching processing. And a chamber for performing the above.

  The alignment chamber 1 is connected to a transfer chamber 2 having a plurality of chambers, and a substrate can be transferred between the transfer chamber 2 and the process chamber 3 via the alignment chamber 1.

  The transfer chamber 2 is connected to a plurality of load lock / unload lock chambers 6.

  It is possible to introduce the substrate supplied from the auto-feeder 5 through the load lock / unload lock chamber 6 into the transfer chamber 2 and to collect the processed substrate from the transfer chamber 2.

  Each of the transfer chamber 2, the process chamber 3, the load lock / unload lock chamber 6 and the alignment chamber 1 includes exhaust means such as a turbo molecular pump and is connected to each other via a gate valve. And can be evacuated.

  Before substrate transport or substrate processing, exhaust is performed in a predetermined chamber where the substrate is to be placed.

  FIG. 2 is a schematic cross-sectional view of the alignment chamber 1 according to the present embodiment, and FIG. 3 is a schematic plan view illustrating a substrate mounting state and a light-shielding sensor arrangement state according to the present embodiment.

  In the alignment chamber 1, the arm of the transfer robot 4 provided in the adjacent transfer chamber 2 can be inserted through the transfer passage 201 opened in the vacuum container 202, and thus the substrate 200 can be transferred. .

  The alignment chamber 1 is provided with a substrate stage 12 that can be rotated in-plane with the substrate placed thereon. The substrate stage 12 rotates in response to a rotation command from the control device 13 and outputs a rotation angle signal indicating the actually rotated angle to the control device 13.

Further, a light shielding sensor 11 is provided at a location that is a predetermined distance away from the virtual center of the placed substrate 200 (the rotation center of the substrate stage 12) and is near the end of the substrate 200. The distance from the center of rotation of the substrate stage 12 can be measured.
In the present specification, the “virtual center” is a point to be corrected for the center of the substrate that is shifted and placed on the substrate holding means such as the substrate stage, and serves as a reference for aligning the center of the shifted substrate. A point (for example, the rotation center of the substrate stage 12) is indicated.

  Specifically, in the present embodiment, the light shielding sensor 11 includes a linear light emitting unit 11a having an LED array and a linear light receiving unit 11b having a CCD sensor and the like. The light emitting portion 11a and the light receiving portion 11b are provided at positions facing each other across the end portion of the substrate along the radial direction of the substrate stage 12.

  The light emitted from the light emitting unit 11a is received by the light receiving unit 11b. Depending on the region of the substrate 200 that blocks the light emitted from the light emitting unit 11a to the light receiving unit 11b, the light receiving unit 11b (the light shielding sensor 11). ) Changes the amount of light (light shielding amount). That is, as the light shielding amount increases, the area of the substrate 200 that blocks the light increases, and the distance between the end of the blocking area and the rotation center of the rotary holder 12 increases. Thus, there is a correlation between the light shielding amount and the distance between the end of the substrate 200 and the rotation center (virtual center) of the substrate stage 12. Therefore, measuring the light shielding amount at a certain moment (a measurement location on the substrate 200) means that the in-plane direction distance between the measurement location where the light shielding amount is detected and the rotation center (virtual center) at the certain moment. It is synonymous with measuring.

  The light shielding sensor 11 detects the light shielded at the end of the substrate 200 among the light from the light emitting part 11a by the light receiving part 11b, and outputs it to the control device 13 as a light shielding amount signal. The substrate stage 12, the light shielding sensor 11, and the control device 13 for controlling them are included in the substrate positioning device of this embodiment.

  The control device 13 receives the light shielding amount signal from the light shielding sensor 11 and the rotation angle signal from the substrate stage 12 at a predetermined time interval during the rotation of the substrate stage 12, and a measurement waveform corresponding to these signals. Based on this, a substrate positioning operation described later is executed.

  In the present embodiment, the rotation angle signal from the substrate stage 12 is an output pulse of a rotary encoder built in the substrate stage 12, and the rotation angle is calculated based on this. That is, when the rotary encoder has a predetermined point at the end portion of the substrate 200 as a reference point, a line segment connecting the reference point and the rotation center (virtual center) of the rotary holder 12 and a reference point other than the reference point at the end portion are used. The angle (rotation angle) formed by the line connecting the point (measurement location) and the rotation center of the rotary holder 12 can be acquired.

  The control device 13 is configured by a computer or the like that is operated by a program, and includes a CPU (not shown) that executes processing operations such as various calculations, control, and determination. In addition, the control unit 13 includes a storage unit (not shown) that stores various control programs executed by the CPU. The storage unit can also include a memory unit that temporarily stores data during CPU processing operations, input data, and the like. The storage unit also stores a program that causes the computer to operate as the control device 13.

  FIG. 4 is a flowchart illustrating processing for positioning the substrate in the control device 13 according to the present embodiment.

  First, the control device 13 detects that the substrate 200 has been placed on the substrate stage 12 (step S101).

Next, the control device 13 transmits a rotation command to the substrate stage 12 to rotate the substrate stage 11 (step S102), receives a light shielding amount signal from the light shielding sensor 11, and receives a rotation angle signal from the rotary encoder. At this time, the rotary encoder acquires the rotation angle at a predetermined time interval and transmits the rotation angle signal to the control device 13, but the light shielding sensor 11 synchronizes with the predetermined time interval. Is transmitted to the control device 13. In this process, since the rotation angle is acquired at every predetermined time interval, the respective rotation angles at a plurality of locations on the end portion (circumferential portion) of the substrate 200 are acquired, and the light shielding amount at the location is acquired. Will do. That is, the light shielding sensor 11 and the rotary encoder transmit the light shielding amount signal and the rotation angle signal in association with each other so that the control device 13 can recognize the light shielding amount at a certain rotation angle.
The control device 13 plots the light shielding amount with respect to each rotation angle based on the received light shielding amount signal and the rotation angle signal, and acquires a measurement waveform (step S103). At this time, since the light shielding amount signal and the rotation angle signal are transmitted synchronously from the light shielding sensor 11 and the rotary encoder, by plotting these signals, the measured waveform is a waveform close to a sine curve as shown in FIG. Appears as
Note that, as described above, measuring the light shielding amount is nothing but measuring the in-plane direction distance. Therefore, the measurement waveform shown in FIG. 5 includes the rotation angle of the substrate 200, the end portion of the substrate 200, and the like. It can also be said that the measurement waveform indicates the relationship with the distance (in-plane direction distance) between the rotation center (virtual center) of the substrate stage 12.

  Thereafter, the control device 13 estimates the maximum eccentric position at which the light shielding amount is maximum as shown in FIG. 6 from the measurement waveform acquired in step S103, according to a predetermined calculation rule, and the amplitude (maximum amplitude A1) and An angle (maximum eccentric position angle α1) is calculated (step S104).

  As a calculation rule, for example, a measurement value in the vicinity where the amplitude is maximum is extracted, and an inflection point where the amplitude changes from an increasing tendency to a decreasing tendency as the angle increases is set as the maximum eccentric position, and the amplitude A1 and the angle α1. Is calculated.

Next, the control device 13 substitutes the angle α1 and the amplitude A1 calculated in the above-described steps for the angle α and the amplitude A in the following formula (1), and sets the approximate expression Y (step S105).
Y = Asin (θ + α) + B (1)

  FIG. 7 is a diagram for explaining symbols A and B in the equation (1). FIG. 7 shows a state where the substrate center of the substrate 200 and the rotation center of the substrate stage 12 are shifted.

Here, the symbol B is the center value of the amplitude, and is the light shielding amount when the substrate center and the rotation center of the substrate stage 12 are rotated in alignment. Symbol A is the distance between the rotation center of the substrate stage 12 and the substrate center of the substrate 200.
Note that the symbol A changes according to the displacement of the substrate 200. Symbol B is a constant determined by the substrate size, and is measured in advance according to each substrate size (that is, according to the light shielding amount when the substrate center and the rotation center of the substrate stage 12 coincide with each other). A table or the like may be stored in advance in the storage unit of the control device 13 in association with the substrate size. By doing in this way, the control apparatus 13 can acquire the appropriate constant B with reference to the said table according to the size of the board | substrate 200. FIG.

  Next, the control device 13 obtains a sum Dt of differences between the approximate expression set in step S105 and the measurement waveform acquired in step S103, and a memory unit (not shown) included in the storage unit of the control device 13. (Step S106). In the present embodiment, the total sum Dt is calculated by calculating the difference Dn at every fixed interval R, calculating the sum of the entire circumference (360 °), and storing it in the memory unit.

  Thereafter, the control device 13 confirms whether or not the search for the predetermined search range (α1 ± S °) is completed by confirming α> α1 + S and α <α1-S (step S107). Here, the symbol S is a predetermined value.

  When it is confirmed in step S107 that the search for the predetermined search range has not been completed, the control device 13 increases the value of the angle α in the equation (1) from α1 to around θ1 that is a predetermined amount. The shifted approximate expression is set (step S108). At this time, θ1 may be shifted back and forth by n (n is a natural number) times. Next, the control device 13 returns to step S105 and sets an approximate expression for each of the angles α shifted by n · θ1. Next, the control device 13 obtains a difference between each of the set approximate equations and the measured waveform, and stores each obtained difference in the memory unit (step S106). That is, the sum Dt corresponding to each angle α is stored in the memory unit. Therefore, the control device 13 can acquire the angle α corresponding to the total sum Dt by acquiring the predetermined total sum Dt from the memory unit, and can extract the corresponding approximate expression.

  The operations in steps S105 to S108 are performed until it is confirmed in step S107 that the search for the predetermined search range has been completed, and thereby the predetermined search range (α1 ± S °) has been searched. Will be repeated.

  Thereafter, the control device 13 refers to the sum Dt corresponding to each angle a stored in the memory unit, and extracts the approximate expression having the smallest sum Dt from the searched approximate expressions, and the angle α at that time α Is calculated as αmin (step S109). Steps S105 to S109 are first search steps. That is, in the first search step, the control device 13 shifts the value of the angle α in the expression (1) by a predetermined amount, obtains approximate expressions for the angle α of the shifted value, and obtains the obtained approximate expression. From these, an approximate expression having a smaller difference from the measured waveform than the initially set approximate expression is searched.

  Next, the second search step is performed in the same manner as the first search step.

  At this time, the control device 13 sets an approximate expression as the maximum amplitude A1 and the angle α as αmin calculated in step S109 for the amplitude A in the above formula (1) (step S110), A sum Dt of differences from the approximated measurement waveform obtained by shifting the value of αmin by a predetermined amount of θ1 ′ is calculated and stored (step S111).

  Thereafter, the control device 13 confirms whether or not the search for the predetermined search range (α1 ± S °) is completed by confirming α> α1 + S ′ and α <α1−S ′ (step S112). The symbol S ′ is a predetermined amount, and the absolute value thereof is smaller than the absolute value of the symbol S.

  When it is confirmed in step S112 that the search for the predetermined search range has not ended, the control device 13 determines the value of the angle α in the equation (1) from αmin in the same manner as in step S108. An approximate expression shifted in units of θ1 ′, which is a fixed amount, is set (step S113). At this time, θ1 ′ may be shifted back and forth by m (m is a natural number) times. Next, the control device 13 returns to step S110 and sets an approximate expression for each of the angles a shifted by m · θ1 ′. Next, the control device 13 obtains a difference between each of the set approximate equations and the measurement waveform, and stores each obtained difference in the memory unit.

  The shift amount θ1 ′ is set smaller than the shift amount θ1 in the first search step, and the search range (αmin ± S ′ °) is set to be narrower than the search range (αmin ± S °) in the first search step. , Search with high accuracy.

  The control device 13 refers to the memory unit and extracts an approximate expression having the smallest total sum Dt from the approximate expressions searched in this way (step S114).

  Then, this time, the control device 13 searches for an optimum value according to a predetermined optimum rule for the amplitude A in the equation (1) in step S115. As this optimization rule, for example, the value of the amplitude A is gradually shifted from the value of the current maximum amplitude A1, and the sum total over the entire circumference (360 °) of the difference from the light shielding amount of the measurement waveform at a predetermined angle is obtained.

  The value of the amplitude A at which the above sum changes from negative to positive or from positive to negative is searched. If the search range and shift amount are reduced and a plurality of searches are performed, an approximate expression can be obtained with higher accuracy.

  The control device 13 determines a final approximate expression through the above process (step S116). Thereafter, the control device 13 determines the position of the substrate based on the approximate expression determined in step S116 (step S116). As shown in FIG. 7, the position of the substrate can be calculated as the amount of deviation from the center of rotation by determining the symbols A and α.

  Note that the correction of the position of the substrate may be performed by adjusting the position of the end effector when the substrate is taken out by the transfer robot, or a correction device may be provided in the alignment chamber 1.

  In the present embodiment configured as described above, the substrate stage 12 operates as substrate holding means for holding the substrate.

  The light shielding sensor 11, the substrate stage 12, and the control device 13 operate as a distance measuring unit that measures the in-plane direction distance from the virtual center to the end of the substrate in the holding surface of the substrate 200.

  Further, the light shielding sensor 11, the substrate stage 12, and the control device 13 operate as an angle acquisition unit that measures an angle formed by a distance measurement unit with respect to a virtual center of the substrate 200 and a reference point at the end of the substrate 200. .

  Further, the light shielding sensor 11, the substrate stage 12, and the control device 13 measure a plurality of substrate end portions by the distance measuring unit and the angle acquiring unit, and the measurement result is a measurement waveform in which the in-plane direction distance and the angle correspond to each other. It operates as a measurement waveform acquisition means for acquiring.

  The control device 13 approximates the measured waveform to a trigonometric function and based on the approximating means including first and second searching means for shifting the value of the symbol A or α of the approximate expression by a predetermined amount, and the trigonometric function approximated by the approximating means. Thus, it operates as a calculation means for calculating a deviation amount of the substrate center from the virtual center.

  FIG. 8 shows a graph of the actual measurement waveform and the approximate expression obtained as described above. Even if the measurement values vary, the position of the substrate can be obtained accurately by using the approximate expression.

  In particular, as shown in FIG. 9, this is remarkable when the deviation amount between the center position of the substrate 200 and the virtual center (the rotation center of the rotary stage 12) is small, and it is difficult to distinguish the variation in the measurement value from the deviation amount. Even in this case, the approximate expression can be calculated with high accuracy.

(Example)
Next, a test for confirming the effect of the present invention was conducted.
In this test, in the apparatus as shown in FIG. 2, the substrate was placed on the substrate stage 12, and the angle α at the maximum eccentric position was calculated 100 times by the method of the example and the method of the comparative example.
In the method of the example, the approximate expression was obtained by performing the search twice as in the flow shown in FIG. 4, and the value of the angle α at this time was obtained. In the method of the comparative example, the point at which the amplitude of the measurement waveform is maximum is obtained as data at the maximum eccentric position, and the angle at that time is obtained as the angle α.

  The results are shown in FIGS. FIG. 10 shows the results of a test performed when the amount of deviation of the substrate center from the rotation center (virtual center) of the substrate stage 12 is 2.0 mm, and FIG. 11 shows the results when the same amount of deviation is as small as 0.2 mm.

  As shown in these figures, even when the same substrate is measured, when the comparative example is used, the variation in the value of the angle α is large for each measurement. However, according to this embodiment, the angle α is the angle α for each measurement. It can be confirmed that the value of is stable and the variation is small.

  In particular, as shown in FIG. 11, this difference is remarkable when the amount of deviation of the substrate is small. Even in this case, it was confirmed that the position of the substrate can be determined with high accuracy according to the method of the present invention.

  By using the approximate expression, the repeatability in the obtained wafer shift direction was improved.

  The application of the present invention is not limited to the above embodiment. For example, the light shielding sensor may be rotated. Further, a plurality of light shielding sensors may be arranged at three or more locations around the substrate, or a CCD camera capable of detecting the entire circumference may be arranged.

Claims (7)

Substrate holding means for holding the substrate;
A distance measuring means for measuring an in-plane direction distance from a virtual center in the holding surface of the substrate to the edge of the substrate when the substrate is held by the substrate holding means;
An angle for measuring an angle formed by a line segment connecting the virtual center and the reference point of the substrate edge, and a line segment connecting the virtual center and the measurement point where the distance in the in-plane direction is measured by the distance measuring unit. Acquisition means;
Based on the in-plane direction distance measured by the distance measurement unit and the angle measured by the angle acquisition unit, a measurement waveform acquisition unit that acquires a measurement waveform corresponding to the in-plane direction distance and the angle;
Approximation means for approximating the measurement waveform to a trigonometric function;
A substrate positioning apparatus comprising: an arithmetic unit that calculates a deviation amount of the held substrate center from the virtual center based on a trigonometric function approximated by the approximating unit. The approximating means shifts a value of at least one of the symbol A and the symbol α of the approximate formula set in the following formula (1) by a predetermined amount, repeats the operation of calculating the difference between the approximate formula and the measured waveform, and sets the setting The substrate positioning apparatus according to claim 1, further comprising a first search unit that searches for an approximate expression having a smaller difference from the measurement waveform than the approximate expression.
Asin (θ + α) + B (1)   The approximating means shifts back and forth by a predetermined amount smaller than the first searching means for at least one of the values of the symbols A and α searched for by the first searching means and having a smaller difference from the measured waveform. The second search means for searching for an approximate expression having a smaller difference from the measured waveform than the approximate expression searched for by the first search means by repeating the operation of calculating the difference between the approximate expression and the measured waveform. The substrate positioning apparatus according to claim 2, further comprising: A rotating means for rotating the substrate held by the substrate holding means relative to the distance measuring means within the holding surface;
The distance measuring means is disposed at a position away from the virtual center by a predetermined distance, and detects the relatively rotating substrate end portion a plurality of times, thereby detecting the distance from the virtual center at a plurality of locations of the substrate end portion. The substrate positioning apparatus according to claim 1, wherein: In-plane direction distance from the virtual center to the substrate end in the holding surface of the substrate, a line segment connecting the virtual center and the reference point of the substrate end, the measurement location where the in-plane direction distance was measured, and the A measurement waveform acquisition step for acquiring a measurement waveform corresponding to an angle formed by a line connecting the virtual center;
An approximation step for approximating the measured waveform to a trigonometric function;
A substrate positioning program that causes a computer to execute a calculation step of calculating a deviation amount of the substrate center held on the holding surface from the virtual center based on the trigonometric function approximated in the approximation step. A substrate positioning device according to claim 1;
A transfer chamber having a transfer robot for transferring a substrate;
A substrate processing apparatus comprising: a process chamber connected to the transfer chamber and configured to be able to transfer a substrate by the transfer robot, and performing a process on the transferred substrate.   An electronic device manufacturing method, wherein an electronic device is manufactured using the substrate processing apparatus according to claim 6.

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