JPH06216002A - Reduction projection-aligner - Google Patents

Abstract

PURPOSE:To accomplish highly precise superposition by a method wherein the amount of rotational deviation computed by an automatic compensation system, with which relative positional deviation between a reticle and a wafer is measured by the projected image of the reticle using an exposing light, is corrected by rotating the reticle. CONSTITUTION:The amount of deviation of relative rotation of a reticle 2 and a wafer state 8 is measured by an automatic compensation system which recognizes the position of the reticle 2 by the reticle image which passed through a reduction lense 7 using the exposure optical system of a reduced projection- exposure device. The amount of rotational deviation, which is computed by the above-mentioned automatic compensation system, is reflected to the reticle 2 by rotating a reticle stage 6. Consequently, as the correction of rotation by wafer is unnecessitated and reduced by the reduction lense, a highly precise positioning can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to highly accurate alignment of a semiconductor manufacturing apparatus that repeats step-and-repeat exposure while performing alignment.

[0002]

2. Description of the Related Art In the prior art, the position of a reticle, which is an original image, is recognized by using a reticle alignment optical system different from the exposure optical system. For this reason, the original reticle position may be erroneously recognized due to changes in the reticle alignment optical system over time, etc., which may cause misalignment during overlay exposure.

[0003]

In the conventional technique, the position of the reticle, which is the original image, is recognized using a reticle alignment optical system different from the exposure optical system. For this reason, a rotational shift may occur during overlay exposure due to changes over time in the reticle alignment optical system. For this reason, the rotational deviation amount obtained by the automatic compensation system that measures the relative positional deviation amount between the reticle and the wafer by the projected image of the reticle using the exposure light is corrected by rotating the reticle to achieve high-precision overlay. To realize.

[0004]

An automatic compensation system that recognizes the position of a reticle by a reticle image transmitted through a reduction lens by using an exposure optical system of a reduction projection exposure apparatus is used, and the relative rotation of the reticle and the wafer stage is detected. Measure the amount of deviation. By rotating the reticle stage and reflecting the amount of rotation deviation obtained by this automatic compensation system on the reticle, it becomes possible to perform alignment at high speed and with high accuracy.

[0005]

In the past, the reticle alignment optical system different from the exposure optical system was used to recognize the position of the reticle, which is the original image, and there was a case where misalignment occurred due to changes over time in the reticle alignment optical system. .
In the present invention, since the exposure projection system is used and the amount of positional deviation of the reticle is measured from the projected image of the reticle by the exposure light, the position of the reticle can be recognized more accurately. By rotating the reticle and correcting the amount of reticle rotation deviation found by this automatic compensation system, it is possible to realize highly accurate overlay.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

An exposure illumination system (1) for transferring the circuit pattern, a reticle (2) on which the circuit pattern is drawn, a reticle alignment optical system (3) for positioning the reticle, and a reticle alignment mark drawn on the reticle. (4), automatic compensation mark (5) drawn on the reticle, reticle stage (6) for finely moving the reticle, reduction lens (7) for reducing (1/5 or 1/10) the circuit pattern, This embodiment is composed of a wafer stage (8) for step-and-repeat the wafer and an automatic compensation sensor (9) for recognizing the position of a reticle projection image placed on the wafer stage.

The position of the reticle alignment mark of the reticle installed on the reticle stage is recognized by the reticle alignment optical system. The positional deviation amount at that time is corrected by finely moving the reticle on the reticle stage to perform positioning. After positioning the reticle, the exposure light system irradiates the reticle with exposure light. The light passing through the reticle is irradiated onto the wafer stage via the reduction lens. At this time, the exposure light is also radiated to the automatic compensation mark drawn on the reticle, and the projected image of this mark is received by the automatic compensation sensor that recognizes the position of the reticle installed on the wafer stage. Recognize. The plurality of automatic compensation marks drawn on the reticle are sequentially moved on the wafer stage and received by the automatic compensation sensor to recognize the position. By statistically processing the positional deviation amounts of the plurality of automatic compensation marks obtained in this way, the relative rotational deviation amount between the reticle and the wafer stage can be measured.

The relative rotation deviation amount between the reticle and the wafer stage measured by the automatic compensation system can be corrected by minutely rotating the reticle on the reticle stage while monitoring the position of the reticle by the reticle alignment optical system. Therefore, the relative rotational displacement between the reticle and the wafer stage can be zero.

Further, the relative rotational displacement amount between the reticle and the wafer stage measured by the automatic compensation system is
An error occurs due to the drawing accuracy of the automatic compensation mark drawn on the reticle. Therefore, the amount of relative rotational deviation differs depending on the reticle and which automatic compensation mark is used. Therefore, when the relative rotation deviation amount is measured with the reference automatic compensation mark of the reference reticle and the rotation amount is rotationally corrected by the reticle alignment optical system, the correction amount is set so that the shot rotation becomes 0. Add. At this time, the rotation correction amount is given by the following equation (1).

[0011]

[Formula 1] Rs = Ra + Rc Rs: Rotational correction amount of reference reticle Ra: Relative rotation deviation amount obtained by automatic compensation system Rc: Relative rotation deviation correction amount of reference reticle In addition, automatic compensation system is performed for each reticle In this case, in addition to the relative rotation deviation correction amount of the reference reticle, the relative rotation deviation amount of each reticle is added to obtain the relative rotation deviation amount of the reticle and the wafer stage. The rotation correction amount at this time is given by the following (Formula 2).

[0012]

## EQU00002 ## Rs '= Ra' + Rc + Rc 'Rs': Rotational correction amount of each reticle Ra ': Relative rotation deviation amount obtained by the automatic compensation system Rc: Relative rotation deviation correction amount of the reference reticle Rc': Relative rotation of each reticle Deviation Correction Amount In this way, the relative rotation amount between the reticle and the wafer stage is obtained and corrected by the reticle stage, so that exposure can be performed with high accuracy and at high speed.

[0013]

According to the present invention, the relative rotational displacement between the reticle and the wafer stage is corrected by the reticle at the beginning of the lot processing of the wafer. Therefore, the rotation correction by the wafer is not required, and the reduction lens reduces the size. Since (1/5 or 1/10) is set, positioning can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is an overall view of a reduction projection exposure apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic process flowchart for performing the process of the present invention.

[Explanation of symbols]

1 ... Exposure illumination system, 2 ... Reticle, 3 ... Reticle alignment optical system, 4 ... Reticle alignment mark, 5 ... Automatic compensation mark, 6 ... Reticle stage,
7 ... Reduction lens, 8 ... Wafer stage, 9 ... Sensor for automatic compensation.

Claims (1)

[Claims] 1. A pattern detection optical system for recognizing the position of a reduction lens and a wafer, a processing device for signal data obtained from a pattern, a reticle stage for finely moving a reticle as an original image, and a reticle alignment optical for aligning the reticle. System, a wafer stage that steps and repeats the wafer while performing position measurement, and the projected image position of the pattern provided on the reticle by the exposure light is detected by the sensor provided on the wafer stage, and the detected value is statistically processed. It consists of an automatic compensation system that recognizes the position of the reticle. The reduction projection exposure system that measures the position of the overlay pattern on the wafer by the pattern detection optical system and performs overlay exposure by relative alignment with the reticle is an automatic compensation system. By Reduction projection exposure apparatus, wherein the relative rotational displacement of the recognized reticle and the wafer stage rotating the reticle by the reticle stage.