JPH0362512A - Reduction aligner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction projection type exposure apparatus, and particularly to a function of correcting rotational deviation of a mask.

[Conventional technology]

Conventionally, the automatic misalignment correction function in reduction projection exposure equipment has been applied to
The targets were the rotational direction of the wafer, the expansion/contraction direction of the wafer, and cases in which the X-axis did not intersect at right angles to the Y-axis of the X-Y stage.

[Problem to be solved by the invention]

The shift correction of the conventional reduction projection type exposure apparatus described above has the disadvantage that pattern defects increase because it is not possible to automatically correct the shift in the rotational direction that occurs due to the rotation of the mask in the previous process. Rotation caused by the rotation of a mask, which is usually considered to be minute, such as deviations in the rotational direction that suddenly occur in equipment, or deviations that occur due to the stricter overlays in the semiconductor manufacturing process due to higher integration. Any misalignment needs to be automatically corrected.

[Means to solve the problem]

The reduction projection exposure apparatus of the present invention includes an X-Y stage that holds a semiconductor wafer and is movable in the X-Y directions, and a laser that scans alignment marks formed on the semiconductor wafer in a previous process. A light source, a signal detection unit for detecting the scattered light of the laser beam that scanned the mark, and a signal from the signal detection unit is input and waveform processed to calculate the amount of rotational shift of the mask in the process. and a mask alignment section that corrects rotational deviation of the mask based on a signal from the mask alignment control section.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The reduction projection exposure apparatus moves with the wafer 3 placed thereon.
A stage 5, a stage movement length measurement unit 4 that measures the amount of movement of the X-Y stage 5, and a laser oscillator 6 that is necessary to scan the position detection mark formed in the wafer 3 in the previous process. , a signal detection section 11 consisting of a light receiving element, etc., which detects the scattered light of the laser beam that scans the mark via half mirrors 7A and 7B, and a mask alignment which processes the detected signal into a waveform and calculates the amount of rotation of the mask 1. It mainly consists of a control section 12 and a mask alignment section 13 that positions the mask 1 with good reproducibility based on signals from the mask alignment control section 12.

FIG. 2 shows a pattern formed in one exposure on the wafer 3 of FIG. 1 (hereinafter referred to as a one-shot pattern), and shows a case where a rotational shift occurs.
The figure shows the first mark 14 and the second mark for alignment in Fig. 2.
FIG. 2 is a waveform diagram of laser scattered light from a mark 15 received by a signal detection unit 11 and processed by a mask alignment control unit 12. FIG.

To deal with the deviation in the rotational direction of the one-shot pattern that occurred due to the rotation of the mask 1 in the previous process, the X-Y stage 5 on which the wafer 3 is placed is moved in the Y direction, and the first mark 1
4 with the laser beam 2, and then the X-Y stage 5 is
direction, and scans adjacent second marks 15 from the same location in the Y direction. The signal detection unit 11 shown in FIG.
This signal is then processed by a mask alignment control section 12 consisting of a CPU, memory, etc. 3 and 4 show the first mark 14 and the second mark 15.
By comparing the positional differences a and b between the first mark 14 and the second mark 15, the one-shot pattern 10, that is, the amount of rotational deviation of the mask 1 in the previous process can be determined. I understand. Therefore, the value is fed back to the mask alignment unit 13, which includes a chuck, a pulse motor, etc., and the mask 1 is positioned again.

Through the above-described series of operations, it is possible to automatically correct the rotational deviation caused in the previous process, so that pattern defects due to the deviation of the mask 1 can be eliminated.

〔Effect of the invention〕

As explained above, the present invention includes a laser light source for scanning an alignment mark formed on a wafer, a signal detection section for detecting scattered light of the laser light, and a signal detection section that processes the signal to detect the amount of rotational deviation of a mask. By providing a mask alignment control unit that calculates the rotational deviation of the mask and a mask alignment unit that corrects the rotational deviation of the mask, it is possible to correct deviations in the rotational direction of the mask that suddenly occur in the previous process, thereby reducing pattern defects. effective. Furthermore, although overlapping becomes more difficult as products become finer, there is also the effect that the accuracy of overlapping can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing a one-shot pattern with rotational deviation formed on a wafer, and FIGS. and a waveform diagram of a second mark. 1... Mask, 2... Laser light, 3... Wafer,
4... Stage moving length measurement unit, 5... X-Y stage, 6... Laser oscillator, 7A, 7B... Half mirror 1 ■ 0... One shot pattern, 11... Signal detection 12... Mask alignment control section, 13... Mask alignment section, 14... First mark, 15... Second mark.

Claims (1)

[Claims] an X-Y stage that holds a semiconductor wafer and is movable in the X-Y direction; a laser light source for scanning an alignment mark formed on the semiconductor wafer in a previous process;
a signal detection section for detecting the scattered light of the laser beam that scans the mark; and a mask alignment that calculates the amount of rotational deviation of the mask in the step by inputting the signal from the signal detection section and processing the waveform. A reduction projection type exposure apparatus comprising: a control section; and a mask alignment section that corrects rotational deviation of the mask based on a signal from the mask alignment control section.