JPH0547900A - Vacuum suction wafer transfer method - Google Patents

Abstract

PURPOSE:To enhance reliability with mistransfer by vacuum-sucking a wafer on a vacuum suction arm without damage to markedly reduce the manhour and the cost for adjustment of transfer amount to X, Y axis directions and by using cassettes of the same type freely. CONSTITUTION:A vacuum suction arm 2 is moved by y1 (predetermined value) in the downward direction of the Y-axis at a position x0+N.x1 (x0, x1 are desired values) in one directional of the X-axis from the origin 0 with respect to the N-th wafer position, and vacuum suction for the arm 2 is started at this position to move the arm 2 at microspeed in the other direction of the X axis. When the moved amount x3 of the arm 2 at the microspeed is within an allowable range, the arm 2 is made to suck a wafer 9: after suction is confirmed, the microspeed movement of the arm is stopped, and at this position the arm 2 is returned to the origin 0 by moving it by y1 in the upward direction of the Y axis, and by x0+N.x1-x3 in the other direction of the X axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of vacuum suctioning a wafer using a vacuum suction type arm and vertically transferring the wafer.

[0002]

2. Description of the Related Art FIG. 1A is an explanatory view showing a structure of a wafer transfer apparatus which is a subject of the present invention, and FIG. 2 is a perspective view showing an example of a vacuum suction type arm. In FIG. 1 (A), reference numeral 1 is a cassette in which a plurality of wafers 9 are set upright, and 2 is a vacuum suction type arm that vacuum suctions and conveys the wafers 9,
A vacuum suction hole 2A is formed inside the arm and opened on the suction surface (see FIG. 2). An exhaust device, for example, a vacuum pump 4 is connected to the vacuum suction hole 2A of the vacuum suction arm 2 by a hose 10 via an air valve 5.
Since the arm 2 itself enters between the wafers 9 and 9, the thickness d (see FIG. 2) of the arm 2 is as thin as possible (within about 2 mm). Reference numeral 3 is a vacuum sensor for confirming that the wafer 9 is attracted to the arm 2.

Reference numeral 5 is an air valve which is controlled by an external control signal because the arm 2 vacuum-sucks the wafer 9, and is opened when the wafer 9 is vacuum-sucked and closed when it is not. 6 is an X-axis (horizontal) drive unit for controlling the position of the arm 2 in the X-axis (horizontal) direction, for example, an X-axis servomotor, and 7 is a Y-axis for controlling the position of the arm 2 in the Y-axis (vertical) direction. A (vertical) drive unit, for example, a Y-axis servo motor, 8 is a servo controller for controlling these servo motors 6, 7.

FIG. 4 is an operation explanatory view of wafer transfer in an example in which a wafer is stored in a cassette in an ideal state, and FIG. 8 is a flow chart when a wafer is transferred by a conventional method. The operation in this case will be described. In the initial state (before starting), the arm 2 is at the position of the origin O on the upper left side of the cassette 1 in the example shown in FIG. When the Nth wafer is transferred, the arm 2 is moved by the X-axis servomotor 6 from the origin O to the right of the X-axis at x ₀ + N · x ₁ (x ₀ , x ₁ are desired values),
When the first wafer is transferred, it is moved to the right on the X axis by x ₀ + x ₁ and stopped. Next, move the arm 2 downward from this position by the Y-axis servo motor 7 to the Y-axis y ₁ (predetermined value)
Just move and stop. Then, the air valve 5 is opened, and the vacuum suction of the arm 2 is started by the vacuum pump 4 to move the arm 2 leftward in the X-axis by x ₂ (desired value).
The wafer 9 ₁ is sucked onto the wafer 9 and the suction is confirmed by the vacuum sensor 3.

When the wafer suction is not confirmed by the vacuum sensor 3, it is determined that the wafer suction has failed and the arm 2 is stopped as an error. Also, if wafer adsorption is confirmed,
Wafer adsorption is OK, and the arm 2 that has adsorbed the wafer 9 ₁ is moved by the Y-axis servomotor 7 in the Y-axis upward direction by y ₁ . After that, the arm 2 is moved by the X-axis servomotor 6 in the left direction of the X-axis by x ₀ + x ₁ −x ₂ to return to the original origin O position.

In such a conventional wafer transfer method, it is important how to adjust the optimum values of x ₀ , x ₁ , x ₂ , y ₁ . Of these, y ₁ can be adjusted relatively easily by one measurement, but x ₀ , x ₁ , x
Adjustment of ₂ is very difficult. Then, the wafers 9 _{1 to} 9 ₄ are accommodated in the slits S between the cassette walls, respectively, and ideally, the pitches l _{1 to} l ₃ between the wafers are as shown in FIG. It is equal to 1 ₁ = l ₂ = l ₃ for all wafers. In this ideal case, the values of x ₀ , x ₁ and x ₂ can be adjusted relatively easily.

[0007]

However, in reality, as shown in FIGS. 5 to 7, the wafers 9 _{1 to} 9 9 are formed in the slit S.
_{Since 4} moves with a certain degree of freedom, the degree of inclination of the wafer in the slit S (wafer angle) is different for each wafer 9 _{1 to} 9
There is considerable variation for each ₄ . FIG. 5 is an operation explanatory view of the wafer transfer in the first example in which the wafers are actually stored in the cassette, FIG. 6 is an operation explanatory view of the wafer transfer in the second example thereof, and FIG. 7 is a wafer in the third example thereof. It is an explanatory view of operation of conveyance. Thus wafer angle each wafer 9 _to 93 ₄ pitches l ₁ for variations in every to l ₃ also significant for each wafer variations (typically 0.
5 mm to 1.5 mm) is produced.

Thus, the pitch between wafers l _{1 to} l ₃
In the state where there is variation (l ₁ ≠ l ₂ ≠ l ₃ ), the arm 2 moves to the right of the wafer and moves downward in the Y-axis by y as shown in FIG.
After moving by _{1 and then} moving by x ₂ to the left in the X-axis and stopping, the distance between the wafer and the arm is too far from x ₂ , and the wafer may not be able to be sucked by the arm even if vacuum suction is performed. For example, when x ₀ is adjusted according to the wafers 9 ₁ and 9 ₃ , the wafers 9 ₂ and 9 ₄ cannot be attracted to the arm 2.

Normally, in order for the arm 2 to adsorb the wafer 9, the distance between the wafer 9 and the arm 2 must be 1 mm or less, depending on the evacuation capacity of the vacuum pump 4. However, as shown in FIG. 6, the wafer 9 that could not be adsorbed in FIG.
_When the values of x ₀ , x ₁ and x ₂ are adjusted according to ₂ and 9 _4, when another wafer 9 ₁ and 9 ₃ is adsorbed, the arm 2 descends directly above the wafer 9 ₁ and 9 ₃ 9 ₁ ,
It may damage 9 ₃ .

[0010] Also, when the larger of x _1, x ₂ so as not to damage the wafer 9 _1, 9 ₃ be broken in FIG. 6, as shown in FIG. 7, the wafer 9 ₁ when the motion of the x _2, 9 ₃ There is a case where the wafers 9 ₁ and 9 ₃ are tilted due to a shock caused by excessively pushing, and the wafers are not sucked.

All the wafers 9 ₁ , 9 ₂ ...
In order to securely attract the wafers, the arm 2 is attached to the wafers 9 ₁ , 9 ₂
It is necessary to descend as close as possible to ..., but with this adjustment, there is a high possibility that the arm 2 will damage the wafers 9 ₁ , 9 ₂ . Therefore, the adjustment margin becomes very small, and it takes a great deal of experience to make the optimum adjustment. Even if an experienced person makes the adjustment, it takes 8 to 1 to make the adjustment.
It takes as long as 0 hours, and even if adjustment is performed for a long time, a transfer error occurs at a rate of 100 to 200 wafers, and it is necessary to redo the adjustment each time. Therefore, the wafer transfer method as it is is a prototype Although it can be used on the research line, there was a problem that it could not be used on the production line.

Even in the same type of cassette 1, the pitches l ₁ , l _2, ... Of the slits S have an error for each cassette, and if the cassette 1 is replaced, the adjustment must be redone.
For this reason, it is necessary to use a cassette dedicated to transportation, and there is a problem that flexibility of the apparatus is reduced.

Further, even if a dedicated cassette is used, the cassette may be distorted due to long-term use,
If vibration is applied during transportation, there is a problem in terms of reliability such as a transportation error.

The object of the present invention is to attach the X of the vacuum suction arm 2.
The adjustment of the amount of movement in the axis and Y-axis directions can be quickly and easily made to the optimum value, and it is not necessary to use a dedicated cassette (it is possible to improve flexibility) and to improve reliability. ..

[0015]

In order to solve the above problems and to achieve the above objects, the method of the present invention achieves the above objects. As shown in FIG.
Are moved to the vacuum suction type arm 2 from the origin O in the X and Y axis directions by the X-axis and Y-axis drive units 6 and 7, and are sucked by the exhaust device 4 one by one. In the X-axis and Y-axis directions by the driving units 6 and 7 to transfer to the origin O, the vacuum-suction type wafer 2 is moved from the origin O to the X-axis with respect to the N-th wafer position. Position in one direction x ₀ + N · x ₁ (x
₀ , x ₁ is a predetermined value) and is moved by y ₁ (desired value) in the downward direction of the Y axis. At this position, vacuum suction of the arm 2 is started to move the arm 2 in the other direction of the X axis at a slight speed. , When the fine speed movement amount x ₃ of the arm 2 is within the allowable range of the maximum allowable value,
After the wafer 9 is adsorbed to the arm 2 and the adsorption is confirmed by the vacuum sensor 3, the slow speed movement of the arm 2 is stopped, and the arm 2 is moved upward in the Y axis by y ₁ at this position, and the X axis is moved. It is characterized by moving x ₀ + N · x ₁ −x _{3 in the} other direction and returning to the origin O.

[0016]

Operation: The vacuum suction arm 2 is moved to the N-axis by the X-axis drive unit 6.
With respect to the second wafer position, it is moved from the origin O to a position x ₀ + N · x _{1 in} one direction of the X-ray, and then moved by the Y-axis drive unit 7 in the downward direction of the Y-axis by y ₁ . At this position, the vacuum suction of the arm 2 is started by the exhaust device 4. However, at this position, the wafer is not attracted to the arm 2 because the distance between the wafer and the arm 2 is too large.

Instead, there is no possibility that the arm 2 will damage the wafer. Therefore, the arm 2 is moved at a low speed in the X-axis direction by the X-axis drive unit 6 while vacuum suction is performed, and when the fine speed movement amount x ₃ of the arm 2 is within the allowable range of the maximum allowable value, the wafer is slit S. No matter how it is tilted inside, the arm 2 always comes close to the wafer and sucks the wafer. When the wafer is attracted to the arm 2, the vacuum sensor 3 confirms the attraction, and the X axis drive unit 6 is stopped by the signal, and the arm 2 is stopped.

At this position, the arm 2 sucking the wafer is moved by y _{1 in the} upward direction of the Y-axis by the Y-axis drive unit 7,
Then, the X-axis drive unit 6 moves x ₀ + N · x in the other direction of the X-axis.
Is moved by ₁ -x ₃ can be returned to by the origin O, so that the wafer can be taken out from the cassette 1.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 (A) is an explanatory view showing the structure of a wafer transfer apparatus which is the subject of the present invention, FIG. 1 (B) is an explanatory view of one embodiment of the method of the present invention, and FIG. 2 is a vacuum of the present invention. It is a perspective view showing an example of an adsorption type arm. 1 in FIG.
Is a cassette in which a plurality of wafers 9 are set upright, and 2 is a vacuum suction type arm for vacuum-sucking and transporting the wafers 9, and a vacuum suction hole 2A is formed inside the arm and is opened on the suction surface ( See FIG. 2). An exhaust device, for example, a vacuum pump 4 is provided in the vacuum suction hole 2A of the vacuum suction arm 2.
Are connected by a hose 10 via an air valve 5. Since the arm 2 itself enters between the wafers 9 and 9, the thickness d (see FIG. 2) of the arm 2 is as thin as possible (within about 2 mm). Reference numeral 3 is a vacuum sensor for confirming that the wafer 9 is attracted to the arm 2.

Reference numeral 5 denotes an air valve which is controlled by an external control signal because the arm 2 vacuum-sucks the wafer 9, and is opened when the wafer 9 is vacuum-sucked and closed when it is not. 6 is an X-axis (horizontal) drive unit for controlling the position of the arm 2 in the X-axis (horizontal) direction, for example, an X-axis servomotor, and 7 is a Y-axis for controlling the position of the arm 2 in the Y-axis (vertical) direction. A (vertical) drive unit, for example, a Y-axis servo motor, 8 is a servo controller for controlling these servo motors 6, 7.

FIG. 3 is a flow chart when a wafer is transferred by the method of the present invention. The method for carrying out the present invention is
In the wafer transfer apparatus having the above-described structure, the vacuum suction type arm 2 is at the position of the origin O on the upper left side of the cassette 1 in the example shown in FIG. When the N-th wafer is transferred, the arm 2 is moved from the origin O to the X-axis right direction by x ₀ + N by the X-axis servomotor 6.
Move x ₁ (x ₀ , x ₁ are desired values) by x ₀ + x ₁ when transferring the _first wafer 9 _1, and move x ₀ + 2x ₁ when transferring the _second wafer 9 _2. Let it stop. Next, the arm 2 is moved from this position by the y-axis servo motor 7 in the downward direction of the y-axis by y ₁ (predetermined value) and stopped.

Then, the air valve 5 is opened and the vacuum pump 4 is opened.
Then, the vacuum suction of the arm 2 is started, and the arm 2 is moved to X
The axis servo motor 6 is moved to the left of the X axis at a slight speed. When the slow-moving amount x ₃ of the arm 2 is within the permissible range, the wafer is adsorbed to the arm 2 and the adsorption is confirmed by the vacuum sensor 3.
The axis servo motor 7 moves y ₁ upward in the Y axis, and then the X axis servo motor 6 moves n in the X axis left direction.
X ₀ + N · x ₁ −x ₃ when transferring the second wafer
Only x ₀ + x _{1 in} case of transporting the _first wafer 9 _1.
-X ₃ only, x ₀ when the _second wafer 9 ₂ is transferred
The wafer can be taken out from the cassette 1 by moving + 2x ₁ -x ₃ to the origin O together with the arm 2.

Further, the fine moving amount x ₃ of the vacuum suction type arm 2
Is not within the allowable range of the maximum allowable value, it will be regarded as a wafer suction error and an error will occur as the X-axis servo motor 6
To stop the arm 2. Without this, if the vacuum sensor 3 were to fail or if the wafer could not be picked up even if moved at a low speed, the speed would continue to move to the left in the X-axis without any limitation. Therefore, the distance x
₃ is stored in the servo controller 8, and when the arm 2 returns to the origin O after the adsorption, the movement amount x ₀ + N in the right direction of the X axis is
_{· X 1 -x 3, x 0} + x 1 -x 3, x 0 + 2x 1 -x 3
Distance that is moved at a slow speed by automatically subtracting ₃ x ₃
However, the wafer is accurately transported to the position of the origin O and returns.

As described above, according to this embodiment, the X-axis servo motor 6 moves the vacuum suction arm 2 to the Nth wafer position from the origin O in the X-axis right direction to x ₀ + N · x.
Move ₁ and then y ₁ by the Y-axis servo motor 7.
Only the arm 2 at this position by the vacuum pump 4.
Vacuum suction is started and the arm 2 is moved to the left side of the X-axis at a slight speed by the X-axis servo motor 6, and when the minute speed movement amount x ₃ of the arm 2 is within the allowable range of the maximum allowable value, the wafer is mounted on the arm 2. Adsorb 9

After confirming the adsorption by the vacuum sensor 3,
The slow speed movement of the arm 2 is stopped by stopping the X-axis servo motor 6, and the arm 2 is moved to the Y-axis servo motor 7 at this position.
Is moved by y _{1 in the} upward direction of the Y-axis, and then by the X-axis servomotor 6, x ₀ + N · x ₁ −x _{3 is} moved in the left direction of the X-axis.
Since the wafer 9 is moved back to the position of the origin O, the wafer 9 can be vacuum-sucked without damaging the wafer 9, and the man-hours and cost for adjusting the movement amount in the X-axis and Y-axis directions can be reduced. Compared with the method, it can be reduced by about 70%, and the adjustment can be performed quickly and easily to the optimum value, and it is not necessary to use a dedicated cassette (to improve flexibility), and it is possible to use the same type cassette. Not only can it be used, but in the conventional method, one out of every 100 to 200 sheets has a transport error, whereas a transport error is 4
The ratio can be reduced to 1 out of 000 to 5000, and the reliability can be improved.

Further, the fine moving amount x ₃ of the vacuum suction type arm 2
Is set within the allowable range of the maximum allowable value, the arm 2 is stopped as an error when the wafer 9 cannot be vacuum-sucked to the arm 2. Therefore, even if the vacuum sensor 3 fails, the wafer 9 can be moved even at a slight speed. Even if the wafer cannot be adsorbed, it does not continue to move to the left in the X-axis at an infinite speed, and even if the distance x ₃ moved at a slow speed differs for each wafer 9, the wafer 9 is accurately returned to the position of the origin O. be able to.

[0027]

Effects of the Invention According to the present invention As apparent from the foregoing description, x ₀ in one direction X-axis from the origin O by X-axis driving unit 6 of the vacuum suction type arm 2 with respect to N-th wafer position
Move by + N · x ₁ , then y by the Y-axis drive unit 7.
₁ Hold and move the arm 2 by the exhaust device 4 at this position.
Vacuum suction is started to move the arm 2 by the X-axis drive unit 6 in the other direction of the X-axis at a slow speed. When the slow-moving amount x ₃ of the arm 2 is within the allowable range of the maximum allowable value, the wafer is transferred to the arm 2. 9 is sucked and the suction is confirmed by the vacuum sensor 3, and then the slow speed movement of the arm 2 is stopped by stopping the X-axis drive unit 6, and the arm 2 is moved by the Y-axis drive unit 7 at this position.
Since it is moved by y _{1 in the} axial direction and then moved by x ₀ + N · x ₁ −x _{3 in the} other direction of the X axis by the X-axis drive unit 6 to return to the position of the origin O, the wafer 9 is moved. The arm 2 can be vacuum-adsorbed without damage,
The number of man-hours and costs for adjusting the movement amount in the X-axis and Y-axis directions can be significantly reduced, and the adjustment can be easily performed to the optimum value.

Further, it is not necessary to use a dedicated cassette, and not only can the cassettes of the same type be used freely, but also the transport mistakes can be greatly reduced as compared with the conventional method, which is reliable. It is possible to improve the sex.

[Brief description of drawings]

FIG. 1A is an explanatory diagram showing a configuration of a wafer transfer apparatus which is a target of the present invention, and FIG. 1B is an explanatory diagram of one embodiment of a method of the present invention.

FIG. 2 is a perspective view showing an example of a vacuum suction type arm according to the present invention.

FIG. 3 is a flow chart when a wafer is transferred by the method of the present invention.

FIG. 4 is an operation explanatory diagram of wafer transfer in an example in which wafers are stored in a cassette in an ideal state.

FIG. 5 is an operation explanatory diagram of wafer transfer in a first example in which wafers are actually stored in a cassette.

FIG. 6 is an operation explanatory diagram of wafer transfer in the same second example.

FIG. 7 is an explanatory view of a wafer transfer operation in the third example.

FIG. 8 is a flowchart when a wafer is transferred by a conventional method.

[Explanation of symbols]

1 cassette 2 vacuum suction type arm 2A vacuum suction hole 3 vacuum sensor 4 exhaust device (vacuum pump) 6 X-axis drive unit (servo motor) 7 Y-axis drive unit (servo motor) 9 wafers 9 _{1 to} 9 ₄ wafers O Origin x ₀ , x ₁ Desired value x ₃ Fine speed movement y ₁ Predetermined value

Claims (2)

[Claims] 1. A plurality of wafers (9) placed upright in a cassette (1) are placed on a vacuum adsorption type arm (2) as an origin by an X-axis and Y-axis drive unit (6, 7). It is moved from O in the X and Y axis directions and is adsorbed one by one by the exhaust device (4). In this state, the arm (2) is moved in the X and Y axis directions by the drive section (6, 7). In the vacuum suction type wafer transfer method of transferring the vacuum suction type arm (2) to the origin O, the vacuum suction type arm (2) is located at a position x ₀ + N · x ₁ (x ₀ , x _{1 in the} X axis direction from the origin O with respect to the Nth wafer position.
₁ is a desired value and is moved by y ₁ (predetermined value) in the downward direction of the Y axis, and at this position, vacuum suction of the arm (2) is started to move the arm (2) in the other direction of the X axis at a slight speed. Then, when the slow-moving amount (x ₃ ) of the arm (2) is within the allowable range of the maximum allowable value, the wafer (9) is sucked onto the arm (2) and the suction is confirmed by the vacuum sensor (3). After that, the slow speed movement of the arm (2) is stopped, and at this position, the arm (2) is moved in the Y-axis upward direction by y _{1 and is} moved in the X-axis other direction by x ₀ + N · x ₁ −x _3. A vacuum suction type wafer transfer method, characterized in that it is returned to the origin O. 2. When the wafer (9) cannot be vacuum-sucked to the arm (2) within the permissible range of the maximum permissible value of the slow-moving amount (x ₃ ) of the vacuum-suction type arm (2), the arm (2) is judged as an error. The vacuum suction type wafer transfer method according to claim 1, wherein the step (4) is stopped.