JPH05102008A - Semiconductor aligner - Google Patents

Abstract

PURPOSE:To provide a semiconductor manufacturing apparatus wherein it can be restored automatically to a normal sequence against an error caused by an indefinite external disturbance. CONSTITUTION:In a semiconductor aligner, a wafer is aligned with a reticle original plate before a pattern which has been drawn on the reticle original plate is projected on a plurality of regions which are arranged on a wafer. In the semiconductor aligner, when a measurement can not be performed or a measured value is abnormal in an alignment operation and in an exposure sequence (303, 306), the aligner is returned automatically to previous steps (3-1, 302 =) according to the number of generated abnormalities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a TT through a projection optical system.
The present invention relates to a semiconductor exposure apparatus that aligns a wafer by the L method.

[0002]

2. Description of the Related Art In a conventional wafer aligning process in a semiconductor exposure apparatus, an error processing mode is set in the apparatus in advance when a measurement is impossible or a correction value tolerance is exceeded. It is disclosed in Japanese Examined Patent Publication No. 01-041012.

[0003]

However, in the conventional example, when an error such as an unmeasurable error or an overcorrection tolerance occurs in the alignment process, the sequence will not be executed unless artificial judgment measures (continuation or manual assist) are added. I can't send next.

On the other hand, as one of the causes of the above-mentioned error occurrence, there are signals due to indefinite disturbances, damascene, etc., and there are also errors that can be easily recovered by manual assist or retry as described above. The method of adding an artificial assisting means to such an error causes inconvenience to an unmanned manufacturing line for the purpose of recent miniaturization and improvement of yield.

Further, in the conventional semiconductor exposure apparatus,
When the measurement is impossible or the correction value tolerance is exceeded in the alignment process, and if this is a trouble in the operation of the apparatus, the sequence is not continued, which causes a heavy burden on the operator and takes a long time.

The present invention has been made in view of the above problems of the prior art, and provides a semiconductor manufacturing apparatus capable of automatically recovering to a normal sequence with respect to an error due to an indefinite disturbance without intervention of operator's judgment. With the goal.

It is another object of the present invention to provide a semiconductor manufacturing apparatus capable of reducing the operator's judgment time and labor at the branch point of the sequence in the alignment process to reduce the operator's burden and improve the throughput.

[0008]

In order to achieve the above object, according to the present invention, it is possible to execute a next step such as measurement failure due to a temporary abnormal situation due to an uncertain disturbance and correction value tolerance overshoot. When it becomes impossible, the conventional defect can be complemented by returning to the sequence one step before.

In the above arrangement, the operator can preset the parameters that define the desired work in case the measurement cannot be performed or the correction value tolerance is exceeded in the alignment process of the exposure apparatus. That is, various types of paths in the sequence shown in FIG. 1 are set in advance with parameters. With such a configuration, when an abnormal situation occurs continuously twice or three times, the sequence can be automatically repeated before shifting to the final RL (reload) or MANUAL (manual operation), It is possible to omit the input operation by the operator's judgment at the time of exposure and further improve the throughput.

[0010]

FIG. 2 is a perspective view showing the appearance of a step-and-repeat type semiconductor exposure apparatus to which the present invention is applied. In the figure, a reticle 1 illuminated with light from an exposure light source 10 is held on a reticle stage 2 that is movable in an XY rectangular coordinate plane and rotatable about a vertical axis θ, and the reticle pattern is an exposure lens. It is projected onto the wafer 4 on the wafer stage 6 via the lens 3. This projection optical system is combined with an alignment scope 5 for TTL alignment and observation, and 9 is an image pickup tube therefor. Furthermore, this projection optical system has an off-axis ITV
A pre-alignment system is also provided, and 7 is the objective lens and 8 is the image pickup tube. Reference numerals 11a and 11b denote wafer supply carriers for supplying the wafer to the stage 6, and 12
Reference numerals a and 12b denote wafer recovery carriers that pick up the wafers from the stage 6, and the wafer is handed between these carriers and the stage by the hand device 16 at predetermined stage positions (passing positions). 1
Reference numeral 3 is a CRT display device for selectively displaying the images picked up by the image pickup tubes 7 and 8 on a monitor, 14 is an operation panel having joysticks and switches, and 15 is a console for controlling the system. It is assumed that this semiconductor exposure apparatus has a main CPU that controls the operations of the stage 6, the hand unit 16, the exposure light source 10, and the like while communicating with the console 15.

FIG. 1 shows all of the sequence to be carried out next when a measurement failure or measurement value abnormality occurs in the wafer alignment process when the present invention is applied to the semiconductor exposure apparatus having the above-mentioned configuration. It is a figure showing. Alignment and exposure follow the process shown in FIG. First, a wafer is loaded (step 300).
The stage 6 and the hand device 16 are operated under the control of the main CPU, and the wafer is supplied and set on the wafer stage 6 by the wafer supply carriers 11a and 11b. Next, prior to exposure, the wafer 4 is aligned with the reticle 1.

One of the modes of alignment is AGA, and there is a T from the off-axis ITV pre-alignment systems 7 and 8.
Perform V pre-alignment. This roughly aligns the wafer (step 301).

Next, the AGA Sub is measured (step 302). The AGA Sub measurement uses some shots automatically or previously designated by the operator, finds the relative deviation amount with respect to the reticle in those shot areas, and calculates the magnification of the entire wafer from these relative deviation amounts, Rotation A sequence for obtaining a translational component and chip rotation. As a result, alignment can be performed with higher accuracy than TV pre-alignment. When this value cannot be measured or an abnormally large amount of deviation is measured (step 303), the number of cases is counted and judged, and the AGA measurement (Sub) is performed at the first time (step 302), and at the second time, the TV It is automatically executed by the preset parameter of returning to the alignment and starting again (step 301). When the third measurement failure occurs, MANUAL is executed there (112).

That is, when the first measurement is impossible, the AGA alignment (step 302) with high accuracy in the alignment step of the previous step is performed to perform the alignment again, and when the measurement is impossible again after the re-operation (the second measurement When the measurement cannot be performed), the process returns to the rough TV alignment (step 301) where the amount of displacement is large, and the alignment is performed again. Even if the alignment is not normally performed by the re-operation from the TV alignment step and the measurement becomes impossible in step 303 (third measurement is impossible), the alignment is manually performed.
(Step 112).

If the measurement of Sub in FIG. 3 does not become unmeasurable, then based on the measurement result of step 302, Sub is determined.
b is corrected (step 304), and AGA Ma
In is measured (step 305). What is Main is that more shots including Sub shots are automatically or predetermined by operator's designation, that is, more shot number information is obtained for Sub corrected shots and more precise alignment is performed. Is to do. When the correction value obtained at this stage exceeds the set tolerance, that is, when the Sub correction performed at the previous stage is insufficient (step 306), the number of occurrences is counted and the count value is obtained as described above. The TV pre-alignment of the sequence of FIG.
It returns to 01) and returns to a normal sequence. If the above-mentioned tolerance over occurs again, the count value becomes the second time and the reload sequence 104 is entered.

When the correction value is normally within the tolerance, the main correction is performed, the alignment process is terminated (step 307), and the exposure is performed (step 30).
8).

This embodiment is an example in which the preset parameters are used in step 303, the number of FIG. 1 is used, and in step 306, the number of FIG. 1 is used. The operator sets other paths arbitrarily in advance.

In the process of aligning the wafer in the semiconductor exposure apparatus, there is a mode called D / D in addition to AGA. The present invention can be applied to this mode as well. As shown in FIG. 4, D / D is a mode in which after performing Sub correction (step 404), exposure is performed while performing alignment for each shot. Also in this case, when the measurement is impossible (step 403), the sequence is returned to the preset sequence and the alignment is performed again. When the tolerance is exceeded (step 406), it is determined whether or not it is the first shot. D for the first shot
The / D measurement (step 405) can be switched to the main measurement (step 305) to automatically start over. This also needs to be set in advance. AGA except for the first shot
By setting in advance in the same manner as above, "ignore the shot and perform alignment", "RL" or "A".
You can start over from the sub measurement of GA. "

As a result, even in the D / D mode, the AG
When it is better to perform the alignment in the A mode, it is possible to switch automatically.

In the above description, when the number of error cases is counted, the number of times is limited for the sake of explanation, but this setting can be made arbitrarily.

[0021]

As described above, in response to a state of the apparatus in which it is impossible to perform the next process such as measurement impossible, correction value tolerance over, etc. due to a temporary abnormal situation due to uncertain disturbance, it is automatically performed. By returning to the sequence immediately before the stop sequence and then recovering to the normal sequence, it is possible to realize a device that is strong against sudden disturbance. Furthermore, since the number of assisting actions by humans can be reduced as much as possible, a stable operation type device can be realized without disturbing the environment around the device.

Further, from the above effects, it is possible to realize an exposure apparatus which promotes an unmanned manufacturing process.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a sequence that is performed next when a measurement failure or measurement value abnormality occurs in a wafer alignment process in a semiconductor exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an appearance of a step-and-repeat type semiconductor exposure apparatus to which the present invention is applied.

FIG. 3 is a flowchart of an AGA mode which is one mode of alignment of the semiconductor exposure apparatus.

FIG. 4 is a flowchart of a D / D mode which is one mode of alignment of the semiconductor exposure apparatus.

[Explanation of symbols]

1; reticle, 2; reticle stage, 3; exposure lens, 4; wafer, 6; wafer stage, 10; exposure light source, 11a, 11b; wafer supply carrier, 12a,
12b; carrier for collecting wafer, 14; operation panel, 1
5; Console.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G03F 9/00 H 7818-2H

Claims (4)

[Claims] 1. A semiconductor exposure apparatus that aligns a wafer with respect to the reticle original plate before sequentially projecting a pattern drawn on the reticle original plate onto a plurality of regions arranged on the wafer through a projection optical system. In the semiconductor exposure apparatus, when measurement is impossible or an abnormality occurs in the measured value in the alignment and exposure sequence, the process automatically returns to the previous step according to the number of occurrences of abnormality. 2. The semiconductor exposure apparatus according to claim 1, wherein the automatically returning step is an alignment or pre-alignment step or a wafer reload step. 3. The alignment, pre-alignment,
3. The semiconductor exposure apparatus according to claim 2, wherein the operator can previously select a sequence to be redone next in the reloading or manual operating steps. 4. When the first abnormality occurs, the procedure returns to the alignment step and realignment is performed. When the second abnormality occurs again, the prealignment step is performed again to perform realignment and the abnormality occurs again. The semiconductor exposure apparatus according to claim 3, wherein reloading or manual operation is performed when the third abnormality occurs.