JP2686637B2 - Exposure system monitoring method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for manufacturing semiconductor elements such as ICs, LSIs, and VLSIs, and more particularly, to error processing by enabling the state of the apparatus to be monitored by parallel processing. The present invention relates to a method of monitoring an exposure apparatus for preventing the above.

[Prior Art] In recent years, in an exposure apparatus for manufacturing a semiconductor element, as the degree of integration increases, the positional accuracy of a drive mechanism on the apparatus has become a problem. In particular, the position of the XY stage for moving the wafer in the XY directions, the position of the wafer Z stage for adjusting the focus during exposure, and the position of the reticle on which the circuit pattern is drawn must maintain high accuracy. There is.

In the conventional technique, in the process of exposing a circuit pattern on a wafer, first the reticle is aligned, then the wafer is focused, then the XY stage is aligned.
Since only a process of sequentially controlling a series of operations of exposing at the end (which is called a printing operation) can be executed, the process of controlling the position measurement of the drive mechanism is executed during the execution of this process. There wasn't.

[Problems to be Solved by the Invention] However, when the position measurement of the drive mechanism on the device and the storage and display of data are performed using the above-described conventional technique, the following problems occur.

As described above, since the only process that can be executed in the step of exposing the circuit pattern on the wafer is the process for controlling the baking operation, the measurement process must be serially incorporated in the process for controlling the baking operation. Will not happen. Therefore, (1) the measurement cannot always be performed, and the measurement operation can be executed only immediately before or after the exposure, for example.

(2) By executing (1), the total processing time of the printing operation becomes long, and the throughput decreases. At times, if the measured data is written in the storage device, displayed, etc., the processing time of the baking operation becomes longer. (3) Since the measurement operation is not always performed, it is not possible to immediately respond when an error occurs.

In view of the above-mentioned prior art, the object of the present invention is to constantly measure the position of the stage that holds the original plate or the substrate during the exposure sequence for printing the pattern of the reticle to be the original plate on the wafer as the substrate, This measurement result can be stored, and when an abnormality occurs in the measurement value, the exposure sequence can be made to respond according to the measurement result, and the operator can confirm the stage position during execution of the exposure sequence. It is an object of the present invention to provide a method of monitoring an exposure apparatus which can easily perform the above-mentioned operation and can prevent an incorrect exposure operation from being performed when an error occurs.

[Means and Actions for Solving the Problems] In order to solve the above problems, in the present invention, an original plate (reticle) and a stage for holding and moving one of the substrate (wafer) on which the pattern is printed by exposure, A position measuring device for measuring the position of the stage for controlling the movement of the stage, and for printing the pattern of the original plate on the substrate while controlling the movement of the stage based on the measurement value of the position measurement value. In the method for monitoring an exposure apparatus having the exposure sequence, there is a monitoring sequence that is executed in parallel with the exposure sequence, and the monitoring sequence includes a position of the stage after the stage is positioned according to the exposure sequence. The step of measuring with the position measuring device, and whether the position measurement value of the stage with the position measuring device is normal. A step of judging whether the position measurement value is abnormal, a step of storing the position measurement value in the storage means when the position measurement value is normal, and an error on the exposure sequence side when the position measurement value is abnormal. The exposure sequence includes a determination step of determining whether or not to continue the subsequent sequence when an abnormality is notified from the monitoring sequence side.

The above-mentioned monitoring sequence may include a step of statistically processing the position measurement value or a step of displaying the position measurement value on the display means, the step moving the substrate in the X and Y directions. It can be an XY stage.

Here, when the stage is an XY stage, a plurality of temporal monitor sections for obtaining the position measurement value for the XY stage are provided in the measuring step of the monitoring sequence, or the monitoring sequence is performed for each monitor section. The method may include the step of obtaining a histogram of the position measurement values for the XY stage, or the step of displaying the histogram collectively on the display means at the end of printing of each of the substrates.

Further, the stage may be a Z stage that moves the substrate in the Z direction or an original plate stage that moves the original plate.

According to the monitoring method of the exposure apparatus of the present invention as described above, the exposure sequence for controlling the normal printing operation and the monitoring sequence for measuring the position of the stage of the exposure apparatus and monitoring the position error are processed in parallel instead of serial processing. Since the position of the stage can be measured and the measured values can be stored during the printing operation, and if any abnormalities occur in the measured values, the abnormal information is immediately reflected in the exposure sequence, and the baking operation is performed. You can decide whether to continue. Therefore, even during the exposure sequence, the operator can easily confirm the stage position at any time using the stored measurement values, and if an error occurs in the stage position during the exposure sequence, the next process to be performed is performed. Properly selected can prevent the execution of inaccurate print exposure operations.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of a semiconductor exposure apparatus according to an embodiment of the present invention.

As shown in the figure, this device includes an illumination device 1 including a light source and a shutter, and a reticle 2 on which a circuit pattern is drawn.
Reticle stage 3 for mounting a reticle, a reticle position measuring mechanism 4 for measuring the position of the reticle 2 on the reticle stage 3, and an imaging lens 5 serving as a projection optical system for printing.
A wafer 8 to be printed, and an XY stage 6 that moves in two directions X and Y in an XY plane; a laser interferometer 7 that measures the position of the XY stage 6; A wafer Z stage 9 for moving the wafer 8 in the vertical direction in order to adjust (hereinafter referred to as focusing), an autofocus unit 10 for measuring the focus position of the wafer 8, a control unit such as a CPU, and a storage device. A control box 11 in which is stored and a console 12 for inputting parameters and commands for controlling the apparatus and displaying data and the like are provided.

FIG. 2 shows a flowchart of operation control of this semiconductor exposure apparatus.

In the figure, steps S1 to S15 are a flow of processing for printing a circuit pattern on a wafer (hereinafter, this is referred to as a sequence), and steps S20 to S30 measure the position of the XY stage 6 and store and display it. The flow of the processing (hereinafter, referred to as a monitor) for the above is shown. However, in this example, only the position measurement of the XY stage 6 which is a part of the monitor function is taken up for description.

Further, FIG. 3 shows an outline of drive control of the XY stage 6,
An outline of processing for measuring the position of the XY stage 6 after the XY stage 6 has completed positioning will be described.

In the figure, the t-axis is the time axis, the p-axis is the velocity axis in the region A, and the position axis in the region B.
In area A, the XY stage 6 is driven under speed servo control, in area B, the XY stage 6 is positioned under target servo control, and in area C, the XY stage 6 is moved. Shows that the positioning is completed and the position is maintained.

In the area C, the operator arbitrarily sets the XY stage 6
There are provided a plurality of time regions (hereinafter referred to as measurement windows) W _{1 to} W _{n in} which the position measurement time of can be set. In addition,
The measurement time in each window is represented by t ₁ to t _n . This time t ₁
~ T _n are the values before the sequence and monitor are executed.
It is assumed that the operator has input from the console as a device control parameter.

In this configuration, when the sequence starts,
In step S1 shown in FIG. 2, the reticle 2 is loaded onto the reticle stage 3.

Next, in step S2, the reticle 2 is positioned by measurement by the reticle position measuring mechanism 4 and driving of the reticle stage 3.

In step S3, the wafer 8 is moved to the XY step 6 and the wafer Z.
It is loaded onto the stage 9.

Next, in step S4, the focus of the wafer 8 is measured by the autofocus unit 10 and the wafer Z stage 9 is driven to focus the wafer 8.

In step S5, the XY stage 6 is moved to a preset exposure shot position, and the XY stage 6 is positioned by the measurement value of the laser interferometer 7.

In step S6, the completion of positioning of the XY stage 6 is notified to the monitor, and the start of position measurement of the XY stage 6 is requested.

In this example, a memory area common to the sequence and the monitor is used as the notification means. That is, both the sequence and the monitor write a coded command in the above area as necessary, and the other side reads the command to clear the area.
It enables the exchange of commands between the sequence and the monitor. Therefore, when one writes a command, the other can read the command first, execute it, and then write its own command to the area.

Next, in stage S7, it is checked whether or not there is a notification from the monitor that there is an abnormality in the XY stage position measurement, and if there is a notification that there is an abnormality, then in step S8 it is determined whether or not to continue the sequence. If it is determined to continue, the process proceeds to step S9, and if it is determined not to continue, the process proceeds to step S15. In step S15, it is determined whether or not to retry from the positioning of the XY stage 6, the process proceeds to step S5 if it is retried, and proceeds to step S12 if it is not retried.

If there is no abnormality in the XY stage position measurement value in step S7, the process proceeds to step S9 and exposure is performed.

Next, in step S10, it is checked whether printing for all shots on one wafer has been completed. If all the shots have been printed, step S11
If not, the process proceeds to step S4 to print the next shot.

In step S11, the monitor is notified of a request to display the position measurement data of the XY stage 6. In this example, this notification is performed at this timing, but normally this timing can be arbitrarily set by the operator.

Next, in step S12, the wafer on the XY stage 6 and the wafer Z stage 9 is unloaded.

In step S13, it is checked whether or not all the wafers to be printed have been processed. If all wafers have been processed, the process proceeds to step S14. If not, the process proceeds to step S3 to print the next wafer.

Finally, in step S14, the monitor is notified that the processing of all wafers is completed, and the sequence processing is completed.

On the other hand, during this period, the monitor starts execution simultaneously with the start of the sequence, and the sequence has it in step S20 until it notifies the completion of XY stage positioning in step S6. And when receiving this notification, step S2
Go to 1 and measure the position of the XY stage 6.

Next, in stage S22, it is checked whether or not the position measurement value of the XY stage 6 is normal. If the measured value is abnormal, the process proceeds to step S23, and if the measured value is normal, the process proceeds to step S24. In step S23, the sequence is notified that the measured value is abnormal.

When the position measurement value of the XY stage 6 is normal in step S22, the position measurement data of the XY stage 6 is written in the storage device in step S24.

Next, in step S25, it is checked whether or not the preset measurement time in one measurement window has been reached. When it has reached, it proceeds to step S26, and when it has not reached, it proceeds to step S21 to continue the measurement.

In step S26, XY obtained in one window
The position measurement data of the stage 6 is statistically processed or a histogram is calculated. In this example, the steps
Although the process of S26 is unconditionally executed, normally, the operator can select from the console 12 whether or not to execute this process in advance.

Next, in step S27, it is checked whether or not the measurement is completed for all the measurement windows designated in advance.
If it is completed, the process proceeds to step S28, and if it is not completed, the process proceeds to step S21 to continue the measurement.

In step S28, it is checked whether or not the XY stage position measurement data, the statistical processing result, and the histogram display request notification are sent from the sequence side. If there is a notification, the process proceeds to step S29, and if there is no notification, the process proceeds to step S30.

In step S29, the XY stage position measurement data, the statistical processing result, and the histogram are displayed.

In step S30, it is checked whether or not there is a processing end notification for all wafers from the sequence side. If you are notified,
If the monitor process is terminated and no notification is given, the process proceeds to step S20 to perform the next measurement.

The present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications. For example, in the flowchart of FIG. 2, the process of step S6 on the sequence side is deleted, a process of "notifying the monitor of the end of focusing" is inserted at the end of step S4, and the process of step S21 on the monitor side is changed to " When the focus measurement is performed, the wafer focus measurement is always performed during the printing operation, and a semiconductor exposure apparatus having a function of storing and displaying the measurement value can be realized.

Also. In the flowchart of FIG. 2, the process of step S6 on the sequence side is deleted, and at the end of step S2,
If you insert the process "Notify the monitor of reticle positioning completion" and replace the process in step S21 on the monitor side with "Measure the position of the reticle", the position of the reticle will always be measured during the printing operation. Memorize the measured value,
It is possible to realize a semiconductor exposure apparatus having a display function.

Furthermore, it is also possible to execute the processing of the sequence and the monitor by arbitrarily combining these.

EFFECTS OF THE INVENTION As described above, according to the present invention, the exposure sequence for controlling the normal printing operation and the monitoring sequence for measuring the position of the stage of the exposure apparatus and monitoring the position error are not sequentially processed. Since it can be executed in parallel processing, the position of the stage can always be measured and the measured value can be stored during the printing operation, and when an abnormality occurs in the measured value, the abnormality information is immediately reflected in the exposure sequence, It is possible to determine whether or not to continue the printing operation. Therefore, according to the present invention, the operator can easily confirm the stage position at any time using the stored measurement value even during the exposure sequence, and when an error occurs in the stage position during the exposure sequence, The process to be performed next can be appropriately selected to prevent the execution of an incorrect printing exposure operation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor exposure apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the apparatus of FIG.
And FIG. 3 is a graph showing an outline of the drive and position measurement processing of the XY stage of the apparatus of FIG. 1: Illuminator, 2: Reticle, 3: Reticle stage, 4: Reticle position measuring mechanism, 5: Projection lens, 6: XY stage, 7: Laser interferometer, 8: Wafer, 9: Wafer Z stage, 10: Auto Focus unit, 11: control box, 12:
console

Front Page Continuation (72) Inventor Keisei Yui 53 Imaigami-cho, Nakahara-ku, Kawasaki-shi, Kanagawa Canon Inc. Kosugi Plant (56) Reference JP 63-14431 (JP, A) JP 62-238621 (JP, A) JP 62-203333 (JP, A) JP 62-139327 (JP, A) JP 61-44427 (JP, A) JP 63-111617 (JP, A) Kai 62-125618 (JP, A) JP 62-189509 (JP, A) JP 63-147282 (JP, A) Actual 58-144832 (JP, U) Actual 64-9419 ( JP, U) Information Processing Society of Japan, “New Edition Information Processing Handbook”, 1st edition, 1st edition (SHO 55-3-30), Ohmsha P. 807-809

Claims (9)

(57) [Claims] 1. A stage which holds and moves one of an original plate and a substrate on which a pattern of the original plate is baked by exposure,
A position measuring device that measures the position of the stage to control the movement of the stage, and a pattern of the original plate is printed on the substrate while controlling the movement of the stage based on the measurement value of the position measuring device. In the method for monitoring an exposure apparatus having an exposure sequence for, a monitoring sequence is executed in parallel with the exposure sequence, the monitoring sequence including the position of the stage after the stage is positioned according to the exposure sequence. Through the position measuring device, determining whether the position measurement value of the stage via the position measuring device is normal or abnormal, and measuring the position when the position measurement value is normal. The step of storing the value in the storage means, and if the position measurement value is abnormal, the fact that there is an abnormality on the exposure sequence side is reported. The exposure sequence includes a determination step of determining whether or not to continue the subsequent sequence when an abnormality is notified from the monitoring sequence side. . 2. The monitoring sequence includes a step of statistically processing the position measurement value.
Method for monitoring exposure equipment. 3. The method of monitoring an exposure apparatus according to claim 1, wherein the monitoring sequence has a step of displaying the position measurement value on a display means. 4. The stage is an XY stage that moves the substrate in X and Y directions.
Method for monitoring exposure equipment. 5. The method of monitoring an exposure apparatus according to claim 4, wherein a plurality of temporal monitor sections for obtaining the position measurement values for the XY stage are provided in the measuring step of the monitoring sequence. 6. The method of monitoring an exposure apparatus according to claim 5, wherein the monitoring sequence includes a step of obtaining a histogram of the position measurement value for the XY stage for each monitor section. 7. The monitoring sequence has a step of collectively displaying the histogram on a display unit at the end of printing for each of the substrates.
Method for monitoring exposure equipment. 8. The method of monitoring an exposure apparatus according to claim 1, wherein the stage is a Z stage that moves the substrate in the Z direction. 9. The method of monitoring an exposure apparatus according to claim 1, wherein the stage is a master plate stage that moves the master plate.