JPS6187330A - Manufacturing device for semiconductor devuce - Google Patents

Abstract

PURPOSE:To contrive the improvement in a throughput by changing the accuracy in stage stop position for a step movement according to whether a wafer printing process is a first mask process or an alignment process so as to reduce the time necessary for the step movement of a stage during the alignment process. CONSTITUTION:A stage drive control means comprising a position control means for a fixed point stop in step movement; and a positioning means for effecting the positioning of a wafer 5 to a reticle 1 with moving the reticle minutely at every step movement; are arranged by combination. Then a permissible value of the accuracy in stop position of the position control means of a stage drive control system is changed for the larger or smaller according to whether the movement during the first mask process which requires high stop position accuracy, or the movement during the alignment process in which the stop position accuracy can be rough compared with in said first mask process. Consequently, the control with excessively high accuracy in stop position is reduced thereby enabling the improvement in a throughput of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention 1] The present invention relates to a semiconductor manufacturing device, and more specifically,
! 'The present invention relates to a semiconductor manufacturing apparatus represented by, for example, a step-and-repeat type semiconductor printing apparatus, in which a conductor wafer is moved by an XY stage or the like to advance the process.

[Prior Art] Drive control of an XY stage on which a wafer is mounted and moves in semiconductor manufacturing equipment, particularly step-and-repeat type semiconductor printing equipment, is generally performed by combining two servo systems: speed control and position control. There is.

That is, FIG. 4 shows an example of the speed change pattern of the XY stage, where the horizontal axis is time and the vertical axis is the moving speed of the stage. In FIG. 4, if the stage is started at time t1, in the section SS from time t1 to t4, the speed control servo performs high-speed control with relatively rough stopping position accuracy, and then from time t4 to t5. In the section PS up to, the position control servo performs control with relatively high stopping position accuracy at low speed.

In the speed control servo section SS, the stage has a speed change pattern consisting of an acceleration section AB where it is accelerated at a constant acceleration, a constant speed section BC where it moves at a constant speed Vmax, and a deceleration section CD where it is decelerated at a constant deceleration. The straight lines AS, BC, and CD of acceleration and deceleration in this pattern are determined by the arrival of the stage's current position and the target stop position at time t1, that is, the moving distance. For example, a microcomputer can calculate the acceleration/deceleration and F according to the distance traveled.
Motor speed control servo is performed by extracting the i high speed from the memory table and using it as a set value, and comparing it with the output of the tacho generator connected to the XY stage drive motor.

Further, the position coordinates of the stage are measured by a position measuring means such as an optical scale or a laser interference measuring device.

Switching from the speed control servo to the position control servo is performed when the position of the stage measured by the position measuring means reaches a predetermined position P1 before the target stop position, for example, within 2 μm.

When entering the position control servo section PS, control is performed so that the difference (distance) between the stage position measured by the position measuring means and the stop target position is within a predetermined value, for example, 0.2 μm, and this predetermined value is This is called the tolerance of the stage stop position accuracy. The position control servo is applied at low speed until the stage position is within the tolerance, and once the stage position is within the tolerance, the control is completed.
point) Stage movement ends.

Of the time required for control until the end of the movement of the suit, the time for the position control servo section Ps becomes longer as the tolerance is made smaller.

By the way, in the conventional stage movement control, the wafer baking process is the first mask process (where the pattern of the first layer is baked).
Regardless of whether it is the first mask mode) or the alignment process (alignment mode) that overlays and prints the patterns of the second and subsequent layers, both are the same in order to stop the step movement at a fixed position at the target position. This is done by applying a position control servo with a tolerance value, and the tolerance value is the value set for the first mask process, which requires the highest stopping position accuracy, and is applied to the step movement of all processes. Therefore, for an alignment process that does not require very high stopping position accuracy, control is performed with more stopping position accuracy than necessary.
This has been a hindrance to improving the throughput of semiconductor manufacturing equipment U.

For example, in step-and-repeat semiconductor printing equipment that has TTL auto-alignment capability, high stopping position accuracy is required for the XY stage. This is a step movement for each exposure shot in the first mask process in which the step movement is performed only by the control servo.
This usually requires a stop position accuracy of about 0.1 μm. On the other hand, in the printing process in the previous process on the wafer, alignment marks are used to align the pattern with the reticle pattern using TTL auto-alignment. Since alignment is performed at a high rate of 11JJ, the stop position accuracy of the step movement of the stage is, however, sufficient at 0.5 to 1.0 μm.

Applying a position control servo to all of these movements with a tolerance value of 0.1 μm will unnecessarily lengthen the time required for the stage to stop for the alignment process, and this will result in an increase in throughput. There's room.

[Objective and Summary of the Invention] In view of the above-mentioned circumstances, the present invention provides a stage drive control means having a position control means for stopping the step movement at a fixed point, and a stage drive control means having a position control means for stopping the step movement at a fixed point, and a stage drive control means for positioning the wafer with respect to the reticle every time the step movement is performed. In a combination of positioning means that performs minute movements, there are two types: during movement in the first mask process, which requires high stopping position accuracy, and during movement in the alignment process, which requires coarser stopping position accuracy. The allowable value of the stop position accuracy of the position control means of the stage drive control system (
The present invention aims to provide a semiconductor manufacturing device that can improve the throughput of the device as a result by changing the tolerance value (tolerance value) to a small value and reducing control with unnecessarily high stopping position accuracy. It is something to do.

In order to achieve such a problem, the semiconductor manufacturing apparatus of the present invention sets the tolerance value of the stop position accuracy set in the position control means for controlling the stop position of the step movement of the stage to the first mask. It is equipped with a stop position accuracy changing means that changes depending on whether it is a process or not.

The alignment means in the semiconductor manufacturing apparatus of the present invention includes:
For example, in the TTL automatic alignment system, in a severe case, the stop position accuracy changing means selects a small tolerance value, such as 0.1 μm, in the first mask process, whereas in the alignment process, it selects a larger tolerance value, such as 0. A tolerance value of about .5 to 1.0 μm is selected and the position control means is operated.

Further, in the present invention, the stage drive control means includes a position measuring means for detecting the position of the stage such as an optical scale or a laser length measuring device, and the position control means for controlling the stop position of the stage based on the output of the position measuring means. These components constitute a position control servo system.

Examples of the present invention are as follows.

[Description of Embodiments] FIG. 1 is a block diagram of a step-and-repeat type semiconductor printing apparatus with a TTL auto-alignment function to which the present invention is applied. , is held on a reticle stage 2 that is movable within the XY rectangular coordinate plane and rotatable around the vertical axis θ, and projects the reticle pattern a onto the surface of the wafer 5 on the wafer stage 6 through the projection lens 3, for example. 115 and is projected. The wafer stage 6 is moved in steps by drive control of the X-axis motor 7χ and the Y@motor 7y, thereby forming reduced pattern images b+, b2 . Printing is the process of transferring... one after another.

Prior to printing, the wafer and reticle must be accurately aligned, and the apparatus shown in FIG.
Equipped with TL auto alignment optical system. In other words, the laser beam oscillated by the laser tube 13 is input into the projection lens 3 via the rotating polygon mirror 12, the half mirror 10, the objective lens 9, and the mirror 8.
By rotating the polygon mirror 12, the image of the reticle alignment mark on the wafer and the image printed in the previous process]
- The alignment mark on the top of the mirror is scanned, and the diffracted light generated from the superimposed images is detected by a photoelectric detector (or TV) 11 from a half mirror 10 following a reverse optical path.

Inside the control box 14, the photoelectric detector 11
The driver knows the degree of overlap between the alignment marks on the wafer and the reticle, that is, the relative positional relationship between the wafer and the reticle, from the output signal of the controller and moves the reticle stage 2 minutely.
A system for controlling 121I of equipment 18χ and 18y has been established (
is being pulled. The positive 6IC alignment of the wafer and reticle due to this minute movement f) of the reticle is the pattern @b+
,t)2. . . is performed fii times before each exposure.

On the other hand, the stop position control accompanying the step movement of the wafer stage 6 is performed based on the position coordinate data of the stage 6 detected by the position measuring means of the laser length measuring devices 16χ and 16yF7.

In FIG. 1, the X and Y directions of movement of the wafer stage 6 are
Laser length measuring device 16χ that detects the position coordinates of the components
, 16y guide the laser beam from the laser tube 17 to the stage 6 via the half mirror 15.
Along with the step movement of the stage, a position coordinate detection pulse is taken out as a distance signal from each radar length measuring device, and this pulse is integrated and counted by one circuit in the control box to determine the amount of movement of the stage. The coordinate values of the current position of the wafer stage 6 can be accurately determined.

The resolution and linearity of the pulses of the rape length measuring devices 16χ and 16y have sufficient accuracy (for example, 0.05 μm/1 pulse) for the required alignment accuracy,
When moving from one exposure area to another, the amount of movement is accurately counted by a laser length measuring device, and the wafer stage 6 is moved until the count value indicates a preset correct movement #Jfit. -ru.

By the way, the explanation so far refers to the alignment process for printing the second and subsequent layers, that is, the printing process in which it is necessary to align the pattern printed in the previous process with the reticle pattern. be.

In the alignment process, no matter how precisely the position of the wafer stage is controlled, the alignment of the wafer and reticle is not always sufficient.
Is required.

The reason why alignment using only the wafer stage is insufficient is that the wafer becomes locally distorted due to heat treatment, ion implantation, etc., and that the wafer This occurs due to remaining distortions in the printed pattern inside.

Therefore, in this case, the accuracy of the stop position of the wafer stage 6 is 0.5 to 1, taking into account the alignment caused by minute movement of the reticle.
．． It may be about 0 μm. The position of the wafer stage 6 is relatively corrected by minute movement of the reticle stage through TTL alignment, and the accuracy thereof is usually as high as about 0.1 μm.

On the other hand, in the first mask process, the accuracy of the stopping position of the wafer stage 6 is strict, and the wafer stage alone needs to have an accuracy of about 0.1 μm.

FIG. 2 is a block diagram showing an example of the configuration of the drive control circuit for the wafer stage 6 of this embodiment. Laser length measuring devices 16χ and 16y attached to the stage 6 for XY coordinate position detection are denoted by the reference numeral 16. The driving motors 7χ and 7y for the stage 6 are also represented by the reference numeral 7. This motor 7 includes a tacho generator 30 for detecting its speed.
is installed.

The motor 7 is driven by a drive circuit 22, and its control mode is selectively switched by a main control circuit 26 consisting of a microprocessor or the like.

The speed control servo system includes a current value counter 31 that counts the output of the tacho generator 30, a target value setter 32 that outputs the target value given from the main control circuit 26, and a ( Comparator 3 that compares 1n
It is composed of a control loop including 3.

The position control servo system includes a stage position detector 2 that measures the position of the stage 6 based on the output signal of the laser length measuring device 16.
4, a stage position target setter 25 that outputs the stage stop target position of the destination given from the main control circuit 26, and a stage position target setter 25 that compares the outputs of these position detector 24 and setter 25 and outputs the difference. a position comparator 21 that outputs the tolerance value given from the main control circuit 26, an accuracy setter 28 that outputs the tolerance value given from the main control circuit 26, and a discriminator 29 that compares the output values of the position comparator 27 and the accuracy setter 28 to determine their magnitude. The motor 7 is driven at low speed until the discriminator 29 detects that the output value of the position comparator 27 is within the range of tolerance 1 shift.
The output of the discriminator 29 is given to the main control circuit 26 and the drive circuit 22.

The main control circuit 26 (1) gives a position control or speed melon control command to the drive circuit based on the output of the position comparator 27;

(2) It is detected from the output signal of the discriminator 29 whether or not the stage is within the tolerance of the stop target position, and if the stage is within the tolerance, the drive of the stage is stopped.

(2) From the output of the comparator 33, it is detected whether the value of the counter 31 has become equal to the output value of the setter 32, and if they have become equal, the drive of the stage is stopped unless position control has been performed.

■ Stage position target setting device 25 and speed target value setting device 3
Set target values for each of 2.

(2) Further, in wafer baking, which is a feature of the present invention, a desired tolerance value is selectively set in the accuracy setting device 28 according to the required accuracy depending on the process.

It has the following functions. An input/output device 20 consisting of a CRT display, a keyboard, etc. is also connected to the main control circuit 26, and from this input/output device 26, the operator can input information such as the type of process, such as the first mask process or the alignment process, and the stopping accuracy of the stage 6. You can manually input the tolerance value etc.

Now, to explain the drive control of the stage 6 in the printing operation with reference to FIG. 2, during the step-and-repeat operation, the main control circuit 26 first sets the stop target position as the next shot position in the stage position target setter 25. , first issues a speed control command to the drive circuit 22.

When the XY stage 6 starts moving, a set value for a trapezoidal speed pattern as shown in section SS in FIG. given, and comparing the output of the tacho generator 3° with that counted by the counter 31,
The speed of the motor 7 is controlled via the drive circuit 22.

In this case, the output data of the position comparator 21 is simultaneously monitored by the main control circuit 26, and its value is set to a set value, for example 2.
When it becomes 0 μm, the main control circuit 26 sends the signal to the drive circuit 22.
A command signal for switching from speed control to position control is given to.

When the position control mode is entered, the output of the position comparator 27 and VI
If the output value of the position comparator 27 is larger than the output value of the accuracy setter 28, the drive circuit 22 is caused to continue position control, and the output value of the position comparator 27 is determined by the discriminator 29. When the output value becomes smaller than the output value of the precision setting device 28, a positioning end signal is given from the discriminator 29 to the main control circuit 26, and a stop command is given to the drive circuit 22, thereby completing the control. .

In this case, the main control circuit 26 gives a small tolerance value such as 0.1 μm to the accuracy setter 28 in the first mask process, and 0.5 to 0.5 μm in the alignment process.
A relatively large tolerance step such as 1.0 μm provides a relatively large tolerance value such as 0.5 to 1.0 μm.

FIG. 3 is a flowchart of the stop position accuracy changing operation by the main n, 11 control circuit 26. First, in step 401, the wafer 5 is placed on the wafer stage 6, and in step 402, the micro processor in the main control circuit 16 It is checked whether or not the type of printing process set in the input/output device 20 is an alignment process. If the alignment process is instructed, in step 403 the main control circuit 26 sends the precision setting device 28 a tolerance value of 1 μm.
Set μm.

If the first mask process is instructed instead of the alignment process, a tolerance value of 0.1 μm is set in step 404 instead. Next, in step 405, the wafer stage 6 moves the wafer 5 to the first shot position, and in step 406, position control is performed until the wafer 5 falls within the set tolerance range, and once within the tolerance, the stage is stopped. After this movement, step 40 again
In step 7, it is determined whether or not an alignment process is specified, and if it is an alignment process, TTL auto-alignment is executed in step 408. By executing this alignment, it is determined in step 409 whether or not the positional deviation between the wafer 5 and the reticle 1 is within a tolerance value specified by the input/output device 20, for example, 0.1 μm. The loop of steps 409 and 408 is repeated. When the permissible value is reached, the process proceeds to step 410, where a predetermined printing exposure for that shot is performed.

On the other hand, if it is determined in step 407 that the first mask is the culm, printing exposure is immediately performed in step 410.

After the printing exposure is completed, the main control circuit 26 determines in step 411 whether or not the printing exposure of all shots of the wafer has been completed. If not, in step 412 the main control circuit 26 moves the stage to the next shot position and repeats the process again. Step 406 is repeated to cause the stage to perform a so-called step-and-repeat operation. The step accuracy of stage 6 at this time is
This is the value set in step 403 or 404, and in the first mask process, in the case of 0.1 μm 1 alignment process, the positioning is performed within 1 μmu.

In other words, compared to the conventional method in which the step movement of the stage 6 is uniformly controlled with an accuracy of 0.1 μm in all processes, by setting a loose tolerance of 1 μm in the alignment process, the time it takes for the stage 6 to stop can be reduced, for example. If the travel path is 20 mm, the time will be shortened by 0.1 seconds from about 0.3 seconds to 0.2 seconds, and if the total number of shots on one wafer is about 30 to 6 shots, the time per wafer will be reduced by 0.1 seconds. 3~
An improvement in throughput of about 6 seconds can be achieved, and the effect is significant.

Returning to Figure 3 again, after all shots are completed, step 41
At step 3, the stage 6 moves to a predetermined wafer recovery position, and the wafer is recovered by a hand device (not shown) or the like.

[Effects of the Invention] As described above, according to the present invention, since the wafer printing process changes the stage stop precision of step movement depending on whether the process is the first mask process or the alignment process, most of the number of previous shots is The time required for step movement of the stage in the alignment step, which takes up most of the time, can be shortened, and therefore a great effect can be obtained in improving throughput.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the external appearance of a step-and-repeat type semiconductor printing apparatus to which the present invention is applied, and FIG. 2 is an example of a 1,000M stage drive control circuit for step-and-repeat operation in the previous semiconductor printing apparatus. FIG. 3 is a flowchart of the control method selection operation by the main control circuit, and FIG. 4 is a diagram showing an example of a speed change pattern of the stage. 1: reticle, 2: reticule stage, 3: projection lens, 4: printing illumination light source, 5: wafer, 6: wafer stage, 7χ, 7y, 7: wafer stage drive motor, 9: objective lens, 11: photoelectric detector, 12; Rotating polygon mirror, 13; Laser tube, 16χ, iey, 16
: Laser length measuring device, 11: Laser tube, 20; Input/output device, 22: Drive circuit, 24; Stage position detector, 2
5; Stage stop position target setter, 26; Main control circuit,
27: Position comparator, 28; Accuracy setting device, 29; Discriminator,
30; Tacho generator, 31; Current value counter, 32
: Speed target setter, 33; Comparator.

Claims (1)

[Claims] 1. A stage drive control means having a position control means for stopping the stage at a target stop position within a preset stop position accuracy in order to step-move the stage on which the wafer is mounted, and a wafer relative to the reticle. In a semiconductor manufacturing apparatus that combines a positioning means that performs positioning by moving a reticle and a wafer minutely relative to each other each time a step movement is performed, a first mask process for printing a first layer on a wafer; A semiconductor manufacturing apparatus comprising: a stop position accuracy changing means for changing the permissible value of the stop position accuracy in an alignment process in which printing after the second eye is performed together with a positioning operation by the positioning means. 2. The semiconductor manufacturing apparatus according to claim 1, wherein the alignment means is of a TTL auto-alignment type. 3. Claim 1, wherein the tolerance value selected by the stop position accuracy changing means in the alignment process is larger than the tolerance value selected by the stop position accuracy changing means in the first mask process. The semiconductor manufacturing equipment described in 2. 4. Claim 1, wherein the stage drive control means comprises a position measurement means for detecting the position of the stage, and a position control means for controlling the stop position of the stage based on the output of the position measurement means. The semiconductor manufacturing apparatus described. 5. The semiconductor manufacturing apparatus according to claim 4, wherein the position measuring means is an optical scale. 6. The semiconductor manufacturing apparatus according to claim 4, wherein the position measuring means is a laser length measuring device.