JPH10116778A - Scanning aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress fluctuation of illuminance due to abrupt and significant variation of pulse intensity effectively by storing the exposing amount of exposing pulse determined by monitoring the intensity thereof along with the scanning position of each part at the time of emitting the exposure pulse and then performing corrective exposure using these data. SOLUTION: Intensity of exposing pulse is monitored sequentially by means of a pulse intensity monitor 7. corrective exposure control means 10 reads out an exposure pulse caused abnormality along with preceding and following exposure pulse trains from a pulse intensity storing section 8 and then reads out corresponding data of exposure mask position, reticle stage position, wafer stage attitude, X-Y stage position, etc., from an exposing position storing section 9. An optimal corrective exposure pulse intensity for correcting an accumulated value and an optimal corrective exposure position are calculated tram these data and delivered to a main control section 1 where corrective exposure operation is started at an optimal timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus.

[0002]

2. Description of the Related Art There are various types of scan exposure apparatuses. For a semiconductor exposure apparatus, a wafer and a reticle are placed on a movable table and driven simultaneously to expose exposure light to a projection lens or a mirror. Through which the image of the reticle is printed on the wafer. Recently, even with this type of apparatus, an excimer laser having a shorter wavelength or the like is used as an exposure light source in accordance with miniaturization of a semiconductor process. As is well known, an excimer laser is characterized by emitting light in a pulse.

[0003]

In recent years, excimer lasers for exposure apparatuses have been variously improved, and their performance and reliability have been improved. On the other hand, phenomena such as a pulse defect in which the emission pulse intensity sharply decreases and a pulse drop causing misfire in response to an oscillation command are reported with an increase in power and an increase in repetition frequency.

An exposure control algorithm of a scan exposure apparatus using such a pulsed light source controls the variation of the light emission pulse intensity of the light source by changing the pulse intensity itself, or controls the scan speed or light emission. The frequency is changed to control to reduce exposure unevenness. However, it may not always function effectively against sudden and large fluctuations in light emission intensity, such as a pulse defect or a missing pulse as described above.

An object of the present invention is to provide means for effectively suppressing illuminance unevenness even in such a rapid and large change in pulse intensity.

[0006]

In order to achieve the above object, the present invention provides an exposure pulse monitoring means for monitoring the intensity of an exposure pulse, and stores an exposure amount by the exposure pulse obtained by the monitoring means. An exposure pulse storage means, and a position storage means for storing a scanning position of each unit of the apparatus at the time of emission of the exposure pulse, wherein correction exposure for correcting exposure unevenness can be performed using the exposure pulse storage means. ing.

In a preferred embodiment of the present invention, a correction exposure means for automatically performing the correction exposure is provided. When the exposure amount by the exposure pulse obtained by the exposure pulse monitoring unit is smaller than a certain amount, that is, in the case of underexposure, the exposure pulse of the underexposure is completed after the scanning for exposure is completed. Reading the scanning position of each part of the device at the time of light emission from the position storage means,
Each part of the apparatus is driven to the position to perform correction exposure. In this case, the correction exposure unit reads out the exposure amount of the underexposure exposure pulse and the pulse train before and after the underexposure from the exposure pulse storage unit, and calculates a calculation unit for calculating an exposure amount for optimal correction exposure. And performing the correction exposure based on the value calculated by the calculation means.
In addition, during the scanning exposure, when the exposure amount by the exposure pulse obtained by the exposure pulse monitoring means is less than a certain amount, that is, even in the case of underexposure, the underexposure pulse emission is performed in the exposure process. Exposure control is performed assuming that there is a pulse intensity of an amount that can be regarded as normal.

[0008]

【Example】

(First Embodiment) FIG. 1 shows a block configuration of a scan exposure apparatus according to one embodiment of the present invention. In the figure, 1
Is a main control unit for controlling the entire scanning exposure apparatus, 2 is an exposure mask control system for controlling an exposure mask for limiting an exposure area, and 3 is for scanning a reticle on which a pattern to be transferred to a wafer is drawn. A reticle scanning control system for controlling the reticle stage; 4, a wafer attitude control system for controlling the wafer stage to adjust the wafer attitude so that the exposure surface of the wafer coincides with the image plane of the transfer pattern on the reticle; Wafer scanning control system for controlling XY stage for scanning, 6
Is an exposure control system for controlling the emission intensity, emission frequency and emission timing of an excimer laser as a light source so as to satisfy exposure conditions, 7 is a pulse intensity monitor for monitoring the emission intensity of an exposure pulse, and 8 is the pulse intensity monitor. 7
An exposure pulse storage unit 9 for storing data of an exposure mask, a reticle stage, a wafer stage, and an XY stage for each exposure pulse emission; Pulse storage unit 8
And correction exposure control means for reading out information from the exposure position storage unit 10 and performing processing for correction exposure, and causing the main control unit to perform correction exposure.

With these configurations, when the main control unit 1 outputs a scan exposure command to the exposure mask control system 2, the reticle scan control system 3, the wafer attitude control system 4, the wafer scan control system 5, and the exposure control system 6, respectively. , A series of scan exposure operations is started. During the exposure, the exposure is executed by changing the exposure pulse intensity and the like according to the exposure algorithm while monitoring the output of the pulse intensity monitor 7. At this time, the exposure pulse intensity at the time of emission of each exposure pulse is stored in the exposure pulse storage unit 8, and the position of the exposure mask, the position of the reticle stage, the attitude of the wafer stage, the position of the XY stage, and the like are stored in the exposure position. Stored in the unit 9.

FIG. 2 schematically shows an exposure pulse train applied to a wafer during scan exposure. In the normal exposure, as shown in the figure, the exposure pulse trains having almost the same intensity are exposed so as to be arranged at substantially equal intervals on the wafer.
As shown in the above, the integrated value has the same exposure amount at each point on the wafer, that is, the exposure is performed without exposure unevenness. FIG. 4 shows that the exposure pulse is 1 during the scanning exposure.
It is a figure showing the case where only one missing. In the general exposure algorithm, since the pulse intensity of the exposure pulse is determined from the pulse intensity of the exposure pulse train before the exposure pulse, etc., as shown in FIG. The intensity of the exposure pulse immediately after the drop is increased. Further, the intensity of the pre-exposure pulse of the next exposure pulse is large, and the intensity of the pre-exposure pulse is conversely reduced. FIG. 5 shows the integrated value of the exposure pulse in this case. As can be seen from the figure, it can be seen that uneven exposure has occurred due to the effect of the lack of the exposure pulse. In the case where the exposure pulse is lost during the scanning exposure as described above, the conventional exposure amount control method of determining the pulse intensity of the next exposure pulse from the pulse intensity of the previous exposure pulse train during the scanning exposure, etc. Correction is not possible,
Rather, exposure unevenness may increase. For this reason,
There is also an apparatus that stops exposure when the intensity originally expected for an exposure pulse is equal to or less than a certain value, such as when the exposure pulse is missing.

In order to solve this problem of exposure unevenness, in this embodiment, first, when there is an extreme abnormality in the exposure pulse, that is, when the pulse intensity of the exposure pulse is below a certain value, the exposure algorithm The exposure pulse as specified by the exposure algorithm
The subsequent exposure is performed. The intensity of the exposure pulse is sequentially monitored by the pulse intensity monitor 7. FIGS. 6 and 7 show a state in which a series of exposures has been completed on the assumption that an exposure pulse has been lost and the exposure pulse for which the exposure algorithm has been lost is normal, as described above. In this state, as can be seen from FIG. 7, an underexposed portion exists in a certain portion of the wafer. Therefore, after ending this series of exposure, the correction exposure control means 10
The abnormal exposure pulse and the exposure pulse train before and after it are read out from the pulse intensity storage unit 8, and the corresponding exposure mask position, reticle stage position, wafer stage attitude, XY stage position, and other data are stored in the exposure position. Read from the storage unit 9. From these data, FIG.
The optimum correction exposure pulse intensity for correcting the integrated value and the optimum correction exposure position are calculated and transmitted to the main control unit 1. Upon receiving this data, the main control unit 1 starts a correction exposure operation at an appropriate timing. In the correction exposure, the exposure mask, the reticle stage, the wafer stage, the XY stage, and the like are respectively driven to the positions optimal for the correction exposure based on the data received from the correction exposure control unit 10. Here, when the main control unit 1 designates the optimum exposure pulse intensity and pulse number for the correction exposure, and outputs a correction exposure command to the exposure control system 6, the exposure control system 6 emits a pulse according to the specified data. Perform When a series of operations of the correction exposure is completed in this way, the integrated value in FIG. 7 is in a state in which there is no exposure unevenness as in the case where the normal scan exposure is performed as shown in FIG.

It is needless to say that these correction exposures are effective for the above-mentioned exposure pulse dropout and intensity reduction, and also have the same effect on a plurality of continuous or discontinuous exposure pulse abnormalities. Nor.

[0013]

As described above, according to the present invention, it is possible to prevent the exposure unevenness from being deteriorated due to the abnormality of the exposure pulse in the scanning exposure.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a scan exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram schematically showing an exposure pulse train in scan exposure.

FIG. 3 is a diagram showing an integrated value of an exposure pulse train in scan exposure.

FIG. 4 is a diagram schematically illustrating a case where a missing exposure pulse occurs in scan exposure.

FIG. 5 is a diagram showing an integrated value in a case where a missing exposure pulse occurs in scan exposure.

FIG. 6: Exposure pulses are missing during scan exposure,
FIG. 7 is a diagram schematically illustrating a case where exposure is continued assuming that a normal exposure pulse is obtained by an exposure algorithm.

FIG. 7: Exposure pulses are missing during scan exposure,
FIG. 9 is a diagram illustrating an integrated value when exposure is continued assuming that a normal exposure pulse is obtained by an exposure algorithm.

[Explanation of symbols]

1: main control unit, 2: exposure mask control system, 3: reticle scanning control system, 4: wafer attitude control system,
5: Wafer scanning control system, 6: Exposure control system,
7: pulse intensity monitor, 8: exposure pulse storage unit, 9: exposure position storage unit, 10: correction exposure control unit.

Claims (4)

[Claims] 1. A scanning exposure apparatus which uses a pulse light as an exposure light source to scan each part of the apparatus to perform exposure, wherein an exposure pulse monitor means for monitoring the intensity of the exposure pulse, and an exposure pulse obtained by the monitor means. A scanning exposure apparatus comprising: an exposure pulse storage means for storing an exposure amount; and a position storage means for storing a scanning position of each unit of the apparatus when the exposure pulse is emitted. 2. When an underexposure exposure pulse emission in which the exposure amount detected by the exposure pulse monitoring means is smaller than a predetermined amount occurs, after the exposure scan is completed, the underexposure exposure pulse emission is performed. 2. The scanning exposure apparatus according to claim 1, further comprising: a correction exposure unit that reads a scanning position of each unit of the apparatus from the position storage unit and drives each unit of the apparatus at the position to perform a correction exposure. 3. The correction exposure unit reads an exposure amount of the underexposure exposure pulse and a pulse train before and after the underexposure from the exposure pulse storage unit and calculates an exposure amount for optimal correction exposure. 3. The scan exposure apparatus according to claim 2, further comprising: means for performing the correction exposure based on the value calculated by the calculation means. 4. When underexposure exposure pulse light emission in which the exposure amount detected by the exposure pulse monitoring means is smaller than a predetermined amount occurs, the underexposure pulse light emission can be regarded as normal in the exposure process. 4. The scanning exposure apparatus according to claim 2, wherein the subsequent exposure control is performed assuming that the pulse intensity has been obtained.