JP2000124119A - Aligner and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an aligner from degrading in exposure positional accuracy due to unstable alignment of a reticule with a reticule stage. SOLUTION: A device is manufactured through a method in which a step-and- scan type aligner is utilized, wherein the misalignment of a reticule from a reticule stage is detected (deviation measuring timing) is carried out in a step operation (U-turn timing), which is carried out for the following exposure operation after a scan exposure operation is carried out. A scan exposure operation is carried out at an accurate exposure position in the following exposure (exposure timing), based on this detection result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a step-and-scan type exposure apparatus and a device manufacturing method using the same.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor exposure apparatus, an accurate position of a reticle is guaranteed only by the holding ability of a reticle holding device (usually a reticle stage) after a reticle alignment is completed until the next reticle alignment. I have. Further, this reticle alignment is usually performed at the time of reticle replacement, but the frequency of reticle alignment when the same reticle is continuously used generally differs from user to user. For this reason, after the reticle alignment is completed, if the relative position fluctuates between the reticle holding device and the reticle due to changes in the environment or the influence of vibration and acceleration, the exposure position will shift, and in the worst case, the defective device May be created.

As described above, conventionally, it has been assured that no displacement occurs between the reticle and the reticle stage due to the holding ability of the reticle holding device. In the case of a stepper, however, only dark vibration coming from the apparatus and the environment is usually used. Therefore, a large force is not applied between the reticle and the reticle stage, and it is possible to guarantee that no displacement occurs due to the holding ability of the holding device.

[0004]

However, in an exposure apparatus (scanner) of the step-and-scan type, particularly, one using a large acceleration for high throughput, the force of reticle weight × reticle stage acceleration is 2 per scan. Therefore, there is a problem that the position between the reticle and the reticle stage cannot be stably and accurately maintained for a long time with the holding ability of the reticle holding device.

An object of the present invention is to provide an exposure apparatus of a step-and-scan type and a device manufacturing method using the same in which exposure is performed due to instability of a position between a reticle and a reticle stage. An object of the present invention is to prevent deterioration of position accuracy.

[0006]

In order to achieve this object, according to the present invention, in a step-and-scan exposure apparatus, after a scan exposure is completed, a step between a reticle and a reticle stage is performed during a step operation for performing the next exposure. It is characterized by comprising a displacement detecting means for detecting the displacement. Thus, the exposure is always performed at an accurate exposure position based on the positional shift between the reticle and the reticle stage detected during each scan exposure.

In the device manufacturing method according to the present invention, when a device is manufactured by performing exposure using a step-and-scan type exposure apparatus, after a scan exposure is completed, a step operation for performing the next exposure is performed. In this method, the displacement between the reticle and the reticle stage is detected, and the exposure position is corrected based on the result, thereby preventing the exposure position accuracy from deteriorating.

[0008]

In a preferred embodiment of the present invention, the position shift detecting means detects the position shift between the reticle and the reticle stage after the completion of the scanning exposure.
This is performed during a period when the moving speed of the reticle becomes substantially zero before the next scanning exposure, that is, when the reticle stage is about to make a U-turn for the next scanning operation. Then, there is provided a means for correcting the exposure position based on the positional deviation detected by the positional deviation detecting means in this manner.

The detection of the positional deviation is performed, for example, by detecting a reticle alignment mark normally provided in the reticle. The exposure position is corrected by giving the detected position shift amount to the exposure position control amount of the reticle stage and / or the wafer stage as a correction amount.

[0010]

FIG. 1 is a view showing a main part of a step-and-scan type exposure apparatus according to an embodiment of the present invention, and the features of the present invention are well represented. In the figure, 1 is a reticle, 2 is a reticle stage having a reticle holding function, 3 is a wafer on which the pattern of the reticle 2 is exposed, 4 is a wafer stage, and 5 is a projection optics that projects the pattern of the reticle 1 onto the wafer 3. System, 6 is reticle 1
A reticle alignment optical system for detecting an alignment mark on the reticle 1 and a driving system thereof; 8 an alignment detecting element for receiving light from the reticle alignment optical system and converting the light into an electric signal; Reference numeral 9 denotes an alignment detection unit that detects a positional shift between the reticle 1 and the reticle stage 2 based on a detection signal from the alignment detection element 8, and 10 synchronizes them based on the detection positions of the reticle stage 2 and the wafer stage 4. A synchronization control unit for performing scan movement, etc.
11 is a reticle stage 2 according to a command from the synchronization control unit 10.
A reticle driving unit for driving the wafer stage 4 in accordance with a command from the synchronization control unit 10;
3 is a bar mirror for position detection provided on the reticle stage 2, 14 is a bar mirror for position detection provided on the wafer stage 4, and 15 is a laser interferometer for detecting the position of the reticle stage 2 using the bar mirror 13. , 1
Reference numeral 6 denotes a laser interferometer for detecting the position of the wafer stage 4 using the bar mirror 14.

Before exposure, the reticle 1 and the reticle stage 2 are at the position b drawn by a solid line, and the wafer 3 and the wafer stage 4 are at the position a drawn by a solid line. It moves to the position b 'and a' drawn by the broken line, respectively. Then, the next exposure operation returns to positions a and b again. Actual wafer stage 4
Is more complex depending on the layout used, but is simplified for illustrative purposes.

FIG. 2 shows a temporal change in the position of the reticle stage 2. As shown in the drawing, when the exposure operation for a certain exposure area on the wafer 3 is completed, the exposure is decelerated for the next exposure area, accelerated in the opposite direction, and synchronized with the wafer stage 4 and the reticle stage 2. Is completed, the next exposure is performed. By repeating this, each exposure area on the wafer 3 is exposed. In each U-turn operation of the reticle stage 2 at this time, as apparent from FIG. 2, the reticle stage 2 travels a relatively long distance for acceleration / deceleration and synchronous settling. Therefore, as shown in FIG. 1, it is possible to position the alignment optical system 7 at a position that does not hinder exposure. Then, via the alignment optical system 7 which can be moved to this position, the signal of the alignment mark is captured by the alignment detecting element 8 during the period of substantially zero speed during the U-turn period of the reticle stage 2, and the alignment detecting unit 9, the positional deviation between the reticle stage 2 and the reticle 1 can be measured.

Reticle stage 2 and wafer stage 4
Are subjected to position measurement by the laser interference systems 15 and 16 and controlled by the synchronization control unit 10 to perform scanning movement for exposure. Therefore, the synchronization control unit 10 instructs the alignment detection unit 9 to start alignment measurement during the period when the speed of the reticle stage 2 is almost 0 (zero),
Correct the next exposure position according to the measured shift amount,
In the next exposure, the driving of the reticle stage 2 and the wafer stage 4 is controlled by the corrected control amount. Thus, the exposure at the precise exposure position is always performed on each exposure area on the wafer 3.

<Embodiment of Device Manufacturing Method> Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 3 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micro machines, etc.). In step 1 (circuit design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next Step 5
(Assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in Step 4,
It includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 4 shows the wafer process (step 4).
The detailed flow of is shown. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), a resist is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus or exposure method to align and print the circuit pattern of the mask on a plurality of shot areas of the wafer.
Step 17 (development) develops the exposed wafer.
In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the production method of this embodiment, it is possible to produce a large-sized device, which was conventionally difficult to produce, at low cost.

[0017]

As described above, according to the present invention,
In a step-and-scan type exposure apparatus and device manufacturing method, a position shift between a reticle and a reticle stage is detected during a step operation, so that a relatively large force is applied between the reticle and the reticle stage, and the reticle position shifts. Even in the case where there is a possibility, it is possible to always perform exposure at an accurate exposure position based on the detected positional deviation.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a reticle shift detection mechanism in a scanner according to an embodiment of the present invention.

FIG. 2 is a view for explaining a relationship among a position of a reticle stage with respect to time, an exposure timing, and a deviation measurement timing in the scanner of FIG. 1;

FIG. 3 is a flowchart showing a device manufacturing method that can use the exposure apparatus of the present invention.

FIG. 4 is a detailed flowchart of a wafer process in FIG. 3;

[Explanation of symbols]

1: reticle, 2: reticle stage, 3: wafer,
4: wafer stage, 5: projection optical system, 6: illumination system,
7: reticle alignment optical system and position drive system
8: alignment detector, 9: alignment detector,
10: reticle / wafer stage synchronization controller, 11: reticle stage driver, 12: wafer stage driver,
13: Bar mirror for reticle stage position detection, 14:
Bar mirror for wafer stage position detection, 15: laser interference system for reticle stage position detection, 16: laser interference system for wafer stage position detection.

Claims (4)

[Claims] 1. An exposure apparatus of a step-and-scan method, comprising: after a scan exposure, a displacement detecting means for detecting a displacement between a reticle and a reticle stage during a step operation for performing a next exposure. Exposure equipment characterized. 2. The apparatus according to claim 1, wherein the displacement detection means detects the displacement between the reticle and the reticle stage during a period in which the moving speed of the reticle becomes substantially zero between the end of the scan exposure and the next scan exposure. 2. The exposure apparatus according to claim 1, wherein: 3. The exposure apparatus according to claim 1, further comprising a unit that corrects an exposure position based on a position shift detected by the position shift detection unit. 4. In a device manufacturing method for manufacturing a device by performing exposure using an exposure apparatus of a step-and-scan method, after a scan exposure is completed, a step between a reticle and a reticle stage is performed during a step operation for performing a next exposure. A device manufacturing method comprising: detecting a position shift of an image; and correcting an exposure position based on the result.