Method to prevent stepper fetch arm from scratching the wafer back and its control device

Method for preventing inhalation arm of stepping machine from scratching crystal back and its control device

The present invention relates to a stepper device used in the semiconductor lithography process, and in particular to a method and control for preventing the fetch arm of the stepper from scratching the wafer back Device.

Figure 1 is a partial component diagram of the wafer loader transport system of the conventional stepper. Please refer to Figure 1. During the whole process of the suction arm 110 getting the wafer 130 from the side slider arm and feeding it into the cassette 100, it is sucked by vacuum until The vacuum is released only when the wafer 130 is put down.

The disadvantage is that when the suction arm 110 enters the wafer boat 110 (from the A1 position to the A2 position), a wafer displacement phenomenon occurs due to the wafer 130 touching the wafer boat 100, which causes the wafer 130 of the wafer 130 and the suction arm 110 to move. The touched part will cause scratches.

Please refer to Figure 2 and Figure 3. Figure 2 is a circuit block diagram of a conventional control device for the suction arm of a stepper. Figure 3 is a timing diagram of the inhalation arm of the conventional stepper.

In Figure 3, the operating steps of the stepper are divided into three operating steps: getting the wafer from the wafer boat, lithography exposure, and putting the wafer back into the wafer boat. The movement of the inhalation arm (fetch arm) is divided into three movements: forward, backward and stop. The vacuum action of the suction device of the suction arm is divided into two actions: releasing vacuum (non-vacuum state) and sucking vacuum (vacuum state).

The lithography exposure step includes other and more operating procedures, but since they are not the focus of the present invention, their operations are not described in detail. The present invention mainly relates to the operation of how to take out and put back the wafer in the wafer boat, and particularly relates to the operation of putting the wafer back into the wafer boat. Therefore, the following topics to be discussed in the present invention are detailed control operations related to putting the wafer back into the wafer boat.

Please refer to Figure 1, Figure 2 and Figure 3 at the same time. The conventional control device for the inhalation arm of a stepper includes a first sensor 200, a second sensor 210, an input interface 220, a micro controller 230, and an output interface. interface) 240 and vacuum solenoid valve 250.

The first sensor 200 and the second sensor 210 are used to sense the position of the inhalation arm 110. The first sensor 200 is used to sense whether the inhalation arm 110 is located at the position A1, and output the first sensing signal S_start; If it is at the A1 position, it outputs a logic high signal; if it is not at the A1 position, it outputs a logic low signal. For example, the inhalation arm 110 leaves the A1 position at time t2, and the inhalation arm 110 returns to the A1 position at time t6.

The second sensor 210 is used to sense whether the inhalation arm 110 is located at the position A2, and output a second sensing signal S_stop; If it is at the A2 position, it outputs a logic low level signal, if it is not at the A2 position, it outputs a logic high level signal. For example, the inhalation arm 110 moves to the A2 position at time t3, and the inhalation arm 110 leaves the A2 position at time t5.

The microcontroller 230 is based on the first sensing signal S_startAnd the second induction signal S_stopGenerate the first control signal S_c(As shown in Figure 3) to control the opening and closing of the vacuum solenoid valve 250, so that the suction arm has the action function of releasing vacuum (non-vacuum state) and sucking vacuum (vacuum state).

Therefore, in the operation step of the conventional stepper (Figure 1) to put the wafer 130 back into the wafer boat 100, the vacuum is sucked at time t1 before the suction arm 110 starts to advance (moves away from the A1 position at time t2), and The vacuum is released at time t4 after the inhalation arm 110 stops (at the position A2 at time t3). Therefore, from time t1 to time t4, the suction arm 110 always maintains the vacuum state. When the suction arm 110 is in the forward state, the wafer 130 is always firmly sucked by it. The disadvantage is that when the suction arm 110 advances (moves from the A1 position to the A2 position) into the wafer boat 110, the wafer 130 may touch the wafer boat 100 and cause wafer displacement. At this time, if the wafer 130 is sucked all the time. The air arm 110 is firmly sucked, which will cause scratches on the part where the crystal back of the wafer 130 and the air suction arm 110 are in contact.

Therefore, the main purpose of the present invention is to improve the operation of the suction arm of the conventional stepper, and prevent the wafer from scratching the back of the wafer during the process of feeding the wafer to the wafer boat. And another object of the present invention is to provide a control device to control the operation of the inhalation arm, which meets the requirements of the present invention.

According to the main purpose of the present invention, a method for preventing the inhalation arm of the stepper from scratching the wafer back is provided, which is suitable for the operation procedure of the inhalation arm in the stepper system to send the wafer into the wafer boat; the feature of the method is The air arm uses vacuum to suck the wafer into the wafer boat and releases the vacuum that is holding the wafer. The vacuum release of the suction arm reduces the displacement between the wafer back and the suction arm when the wafer collides with the wafer boat. The friction force prevents the inhalation arm from scratching the crystal back of the wafer.

According to the main purpose of the present invention, another method for preventing the inhalation arm of the stepper from scratching the wafer back is provided, which is suitable for the operation procedure of the inhalation arm in the stepper system to send the wafer into the wafer boat; the method steps include at least : (A) Before moving the suction arm to the wafer boat, first suck the wafer with vacuum; (b) When the suction arm starts to move to the wafer boat for a certain period of time and the wafer has not been sent into the boat, it will suck The vacuum of the wafer is released; and (c) After the suction arm sends the wafer into the wafer boat, the suction arm stops moving.

According to a preferred embodiment of the present invention, after step (c), it further includes: (d) when the suction arm is in a stopped state, it sucks and releases the vacuum in sequence to confirm whether the wafer is in the wafer boat .

According to another object of the present invention, a control device for the suction arm of a stepper is provided. The suction arm can be moved into the wafer boat by moving the suction arm from the first position to the second position. The vacuum is released to reduce the friction between the wafer back and the suction arm when the wafer collides with the wafer boat and the wafer is displaced, thereby preventing the suction arm from scratching the wafer back; the device at least includes: a first sensor , To sense whether the inhalation arm is in the first position and output a first sensing signal; if the inhalation arm is in the first position, output a logic high level signal, if the inhalation arm is not in the first position, output a logic low level signal ; A second sensor for sensing whether the inhalation arm is in the second position and output a second sensing signal; if the inhalation arm is in the second position, it outputs a logic low level signal, if the inhalation arm is not in the second position It outputs a logic high level signal; an input interface; a microcontroller that receives the first sensing signal and the second sensing signal through the input interface to generate a first control signal; an output interface; a vacuum release controller through the output interface Receiving the first control signal, and receiving the first sensing signal and the second sensing signal to generate a second control signal inside; and, a vacuum solenoid valve, which is controlled by the vacuum release controller to make the suction arm Release the vacuum or hold the vacuum; if the second control signal is a logic low level, the suction arm releases the vacuum; if the second control signal is a logic high level and the first control signal is a logic high level, the suction arm sucks the vacuum ; If the second control signal is a logic high level and the first control signal is a logic low level, the suction arm releases the vacuum.

According to a preferred embodiment of the present invention, the vacuum release controller further includes: a first signal delay circuit for delaying the rising edge of the first sensing signal for a first specific time, and the signal can be adjusted according to different arm movement speeds The delay time to ensure that the suction arm releases the vacuum before the inhalation arm sends the wafer into the wafer; a second signal delay circuit is used to delay the falling edge of the second sensing signal for a second specific time. Prevent the inhalation arm from releasing the vacuum before the inhalation arm reaches the second position; a timing control circuit that generates the second control signal from the output of the first signal delay circuit and the output of the second signal delay circuit; and, an optical isolation A type electronic switch circuit, which uses the first control signal and the second control signal to control the vacuum solenoid valve, so that the suction arm releases the vacuum or sucks the vacuum.

According to another objective of the present invention, another vacuum release controller is provided, which is installed in a stepper suction arm control system, and can move the suction arm from the first position to the second position to send the wafer into the crystal. In the process of the boat, first release the vacuum of the suction arm to reduce the friction between the wafer back and the suction arm when the wafer collides with the wafer boat and the wafer is displaced, thereby preventing the suction arm from scratching the wafer back; The control system includes a first sensor, a second sensor, an input interface, a microcontroller, an output interface, a vacuum solenoid valve, and a vacuum release controller. The first sensor is used to sense whether the suction arm is in the first Position, the second sensor is used to sense whether the inhalation arm is in the second position, the microcontroller is coupled to the first sensor and the second sensor through the input interface, the microcontroller is coupled to the vacuum release controller through the output interface, and the vacuum is released The controller is coupled to the first sensor and the second sensor, and the vacuum solenoid valve is coupled to the vacuum release controller; the vacuum release controller includes at least: a first signal delay circuit, which is coupled to the first sensor, Delay the rising edge of the input signal for a first specific time to output; a second signal delay circuit, which is coupled to the second sensor, can delay the falling edge of the input signal for a second specific time to output; a timing control circuit, which The first signal delay circuit and the second signal delay circuit are coupled, the output of the first signal delay circuit and the output of the second signal delay circuit are processed to generate a second control signal; and, an optically isolated electronic switch circuit, which Coupled with the timing control circuit, the output interface and the vacuum solenoid valve, the vacuum solenoid valve is controlled by the second control signal and the output signal of the microcontroller, so that the suction arm releases the vacuum or sucks the vacuum; The two control signals can forcibly control the inhalation arm to release the vacuum, and the inhalation arm maintains the release of the vacuum from the first specific time after the inhalation arm leaves the first position to the second specific time after the inhalation arm reaches the second position.

According to a preferred embodiment of the present invention, the timing controller is a D-type flip-flop, which uses the output of the first signal delay circuit as the clock signal and the output of the second signal delay circuit as the clear signal, and its complementary output terminal The input terminal is coupled, and the complementary output terminal outputs the second control signal.

In order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, a preferred embodiment is specially cited below, and is described in detail as follows in conjunction with the accompanying drawings:

Figure 1 is a partial component diagram of the wafer loading and conveying system of a conventional stepper; Figure 2 is a circuit block diagram of a control device for a suction arm of a conventional stepper; Figure 3 is a conventional stepper The action sequence diagram of the inhalation arm of the machine; Figure 4 shows the action sequence diagram of the inhalation arm of a stepper according to a preferred embodiment of the present invention; Figure 5 shows the action sequence of a stepper according to a preferred embodiment of the present invention Inhalation arm control device; Fig. 6 shows an implementation circuit diagram of a vacuum release controller 500; and Fig. 7 shows the coupling relationship between the optically isolated electronic switch circuit 540, the output interface 240 and the vacuum solenoid valve 250 .

The present invention proposes an improved solution for scratching the wafer back during the operation of the suction arm of the conventional stepper to send the wafer to the wafer boat, and provides a control device to realize the improved solution. The present invention adds an independent vacuum release controller to the conventional stepper suction arm control device, so that the controller is used in the step of the conventional stepper suction arm to put the wafer back into the wafer boat. , The vacuum is released after a delay time begins when the inhalation arm advances. In this way, when the suction arm enters the wafer boat, if the wafer touches the wafer boat and the wafer is displaced, the contact part of the wafer back and the suction arm has no suction force because the vacuum has been released, so it will not cause scratches. .

Please refer to FIG. 4, which illustrates a timing diagram of the inhalation arm of a stepper according to a preferred embodiment of the present invention. In Figure 4, the operation steps of the stepper, the movement of the suction arm, and the vacuum movement of the suction arm proposed in the present invention are the same as those in the prior art, except that the operation steps of returning the wafer to the wafer boat are the same. The timing of the suction arm holding the vacuum and releasing the vacuum has been changed. Next, the main subject of the present invention is the detailed control operation of putting the wafer back into the wafer boat.

Please refer to Figure 1 and Figure 4 at the same time. From time t1 to time t8 in FIG. 4, the stepper performs the step of putting the wafer 130 back into the wafer boat 100. The vacuum operation in this step is the main technical feature of the present invention.

(1) At time t1, the inhalation arm 110 remains motionless at the A1 position, but the inhalation arm 110 starts to suck the vacuum.

(2) At t2, the inhalation arm 110 starts to move forward and moves from the A1 position to the A2 position. At this time, the vacuum state is still maintained.

(3) At time t3, the suction arm 110 has not yet reached the A2 position and is still moving forward, and the wafer 130 has not been sent into the wafer boat 100. At this time, the suction arm 110 starts to release the vacuum.

(4) At time t4, the suction arm 110 reaches the A2 position and stops moving forward, and maintains the vacuum release state.

(5) At time t5, the suction arm 110 stays at the position A2, and the suction arm 110 starts to suck the vacuum. This action is used to confirm whether the wafer 130 has been placed in the wafer boat 100.

(6) At t6, the inhalation arm 110 still stays at the A2 position, but the inhalation arm 110 releases the vacuum.

(7) At t7, the suction arm 110 retreats and moves away from the A2 position to the A1 position. At this time, the suction arm 110 still maintains the released vacuum state, and the wafer boat 100 moves slightly upwards, so the wafer 130 will be left in the wafer boat Within 100.

(8) At t8, the suction arm 110 returns to the A1 position, and the step of putting the wafer 130 back into the wafer boat 100 is completed.

The above vacuum action of the suction arm is the method proposed by the present invention to prevent the stepper arm from scratching the crystal back. The feature of the present invention is that the suction arm sucks the wafer before placing the wafer into the wafer boat, and first releases the vacuum that the suction arm sucks on the wafer. The release of the vacuum reduces the displacement of the wafer when the wafer collides with the wafer boat. The friction between the crystal back and the suction arm prevents the suction arm from scratching the crystal back of the wafer.

Please refer to Figure 5, which illustrates a preferred embodiment of the present invention is a stepper suction arm control device. The circuits in Figure 5 and Figure 2 are the same, for example, the functions of the first sensor 200, the second sensor 210, the input interface 220, the microcontroller 230, the output interface 240, and the vacuum solenoid valve 250 are the same, so I won't repeat them here. The difference between the two figures is that Figure 5 adds a vacuum release controller 500, which obtains the first sensing signal S_startAnd the second induction signal S_stopSimultaneously with the conventional control device for parallel processing, it can generate a control signal for forcing the inhalation arm to release the vacuum, and cooperate with the conventional first control signal S_cTo control the opening and closing of the vacuum solenoid valve 250, so that the suction arm releases the vacuum or sucks the vacuum.

Please refer to FIG. 6, which shows an implementation circuit diagram of a vacuum release controller 500. The vacuum release controller 500 includes a first signal delay circuit 510, a second signal delay circuit 520, a timing control circuit 530, and a photo isolated electronic switch circuit 540.

The first signal delay circuit 510 is used to convert the first sensing signal S of the first sensor 200_startThe rising edge is delayed for a first specific time (the time t3-t2 in Figure 4). The signal delay time can be adjusted according to different arm movement speeds to ensure that the inhalation arm does not send the wafer into the wafer boat. Release the vacuum.

The second signal delay circuit 520 is used to convert the second sensing signal S of the second sensor 210_stopDelaying the falling edge for a second specific time (the time from t5-t4 in Figure 4) can prevent the inhalation arm from stopping the vacuum before it stops (at time t4 in Figure 4).

The timing control circuit 530 is composed of a D-type flip flop U2B. The D-type flip-flop U2B uses the first signal to delay the output S of the circuit 510_{start_delay}(As shown in Figure 4) is its clock signal, and the output S of the second signal delay circuit 520_{stop_delay}(As shown in Figure 4) for its clear signal, its complementary output terminal Q is coupled to its input terminal D. Therefore, the timing control circuit 530 is delayed by the output S of the first signal delay circuit 510_{start_delay}And the output S of the second signal delay circuit 520_{stop_delay}Generate the second control signal<img file="TW398024B_D0001.tif" />(As shown in Figure 4), to control the timing and duration of vacuum release.

The optically isolated electronic switch circuit 540 is a contactless switch, which is coupled to the output interface 240 and the vacuum solenoid valve 250 of the suction arm control device of the conventional stepper system. Please refer to FIG. 7, which illustrates the coupling relationship between the optically isolated electronic switch circuit 540, the output interface 240 and the vacuum solenoid valve 250. The optically isolated electronic switch circuit 540 uses the first control signal S_c(As shown in Figure 4) and the second control signal<img file="TW398024B_D0002.tif" />(As shown in Figure 4), so that the signal S_{P3_2}As shown in Figure 4, it is used to control the opening and closing of the vacuum solenoid valve 250, so that the suction arm can suck the vacuum or release the vacuum.

Please refer to Figure 4. It can be seen from the above circuit operation that the first control signal S_cWith the second control signal<img file="TW398024B_D0003.tif" />In conjunction with the decision of the suction arm to absorb or release the vacuum, the detailed control status is as follows.

(1) From t1 to t3, the first control signal S_cIs the logic high level and the second control signal<img file="TW398024B_D0004.tif" />Is the logic high level, so that the signal S_{P3_2}It is the logic low level, so the suction arm sucks the vacuum.

(2) From t3 to t5, the first control signal S_cIs the logic high level and the second control signal<img file="TW398024B_D0005.tif" />Is the logic low level, so that the signal S_{P3_2}It is a logic high level, so the inhalation arm releases the vacuum.

(3) From t5 to t6, the first control signal S_cIs the logic high level and the second control signal<img file="TW398024B_D0006.tif" />Is the logic high level, so that the signal S_{P3_2}It is the logic low level, so the suction arm sucks the vacuum.

(4) From t6 to t8, the first control signal S_cIs the logic low level and the second control signal<img file="TW398024B_D0007.tif" />Is the logic high level, so that the signal S_{P3_2}It is a logic high level, so the inhalation arm releases the vacuum.

Therefore, in the first control signal S of the west gas arm control device of the present invention_cThe function is the same as the conventional one, but the present invention uses the second control signal<img file="TW398024B_D0008.tif" />(When it is the logic low level) to force the suction arm to release the vacuum, which meets the design requirement of the invention to release the vacuum before the suction arm puts the wafer into the wafer boat.

It can be seen from the above-mentioned preferred embodiments of the present invention that the method of preventing scratches on the crystal back by the stepper arm and its control device proposed by the present invention can only add a vacuum without changing all conventional control devices. By releasing the controller to force the suction arm to release the vacuum, the design requirement of releasing the vacuum before the wafer is placed in the wafer boat by the suction arm can be achieved. In this way, when the suction arm enters the wafer boat, if the wafer touches the wafer boat and the wafer is displaced, the contact part of the wafer back and the suction arm has no suction because the vacuum has been released, so it will not cause the wafer to move. Scratched crystal back. Therefore, the present invention is beneficial to the subsequent manufacturing process of the wafer and can improve the product yield.

Although the present invention has been disclosed as above in the preferred embodiment, it is not intended to limit the present invention. Anyone familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to the scope of the attached patent application.