JPH02192711A - Contracted projection type exposure device - Google Patents

Abstract

PURPOSE:To enhance the alignment precision by a method wherein He-Ne laser beams scan the part near the alignment mark of a semiconductor wafer through a reticle and a contraction lens while reflected rays are entered into a photodetector to measure any position slip. CONSTITUTION:He-Ne laser beams 9 irradiate an alignment mark 7 on a semiconductor wafer 6 through a reticle and a contraction lens 4 while reflected rays which are diffracted and scattered enter into a photodetector 8. At this time, when a light emitting part 1 is shifted at specific rate, the laser beams 9 scan the part near the mark 7 from the dark part on the reticle 2 to the other dark part on the opposite side passing through slit part. Then, the center of the the mark 7 is measured by analyzing the signal on the part where the signal is changed by the mark 7 of the laser beams 9 transmitting the slit part. Simultaneously, the center of the slit on the reticle 2 is measured to measure the difference in the centers i.e., the overlapped slip amount of the reticle 2 and the semiconductor wafer 6.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a reduction projection type exposure apparatus.

[Conventional technology]

Conventionally, in a reduction projection type exposure apparatus, the alignment of the semiconductor tool (hereinafter referred to as alignment) is performed by directing the laser beam 9 emitted upward from the He-Ne laser emitting part to the half mirror 3 and The area around the diffraction grating alignment mark 7 provided on the semiconductor wafer 6 placed on the stage 5 is irradiated through the reduction lens 4, and the diffracted and scattered reflected light is reflected by the half mirror 3 through the reduction lens 4. The mark position was determined from the change in the intensity of the light detected by the light receiving unit 8 and simultaneously moved the stage 5 to scan the vicinity of the alignment mark 7.

[Problem to be solved by the invention]

The above-mentioned conventional reduction projection type exposure apparatus has a drawback in that the laser beam does not pass through the reticle, and the optical path differs from that during actual exposure, resulting in misalignment.

[Means to solve the problem]

The reduction projection type exposure apparatus of the present invention includes an alignment laser beam generation section, and a laser beam emitted by the laser beam generation section, which scans the vicinity of the alignment mark of the semiconductor wafer through a reticle and a reduction lens, and reduces the reflected light. and a light receiving section that receives light through a lens and detects the position of the semiconductor wafer.

〔Example〕

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

FIG. 1 is a schematic diagram showing an embodiment of the present invention. He-
The laser beam 9 emitted upward from the Ne laser emitting section is emitted from the reticle 2. A diffraction grating-shaped alignment mark 7 provided on the surface of the semiconductor wafer 6 is irradiated through the half mirror 3 and the reduction lens 4.

The reflected light diffracted and scattered by the alignment mark 7 of the semiconductor wafer 6 follows the same path as the incident light, is reflected by the half mirror 3, and reaches the light receiving section 8. By not moving the light emitting unit 1 at a constant speed in the direction of the arrow, the laser beam 9 can scan the vicinity of the alignment mark 7.

FIG. 2 is a schematic diagram showing the relationship between the alignment mark 7, the slit 11 on the reticle, and the trajectory 10 of the laser beam as seen from the position of the light emitting section. When superimposed, the alignment mark 7 on the semiconductor wafer 6 is set to be in the center of the slit 11 on the reticle 2. Laser light,
Scanning starts from the dark area on the reticle 2, passes through the slit 11, and ends at the dark area on the opposite side. In other words, the semiconductor wafer 6 is irradiated only at the slit 11.

FIG. 3 is a characteristic diagram showing the signal intensity at the light receiving section 8 when scanning with laser light. The signal can be roughly divided into three parts. First, while the dark area on the reticle 2 is being scanned, the laser beam 9 does not reach the semiconductor wafer 6, so no signal is output at part A, although it is inside the slit 11.
Part B is far away from the alignment mark 7, so diffraction and scattering does not occur and almost no signal is output, and part C is where the signal changes greatly at the alignment mark 7. Alignment mark 7
The center P of can be found by analyzing the signal of the C portion. In the present invention, the center Q of the slit on the reticle is simultaneously determined, and the difference between P and Q, that is, the misalignment between the semiconductor wafer and the reticle, can be directly measured. In that case, Q can be easily found from the center of the sum of B and C.

〔Effect of the invention〕

As explained above, the present invention uses a He-Ne laser beam to align the reticle and the semiconductor wafer through the reticle and the reduction lens, so that alignment accuracy can be significantly improved compared to conventional methods.

trajectory, 11...slit, 12...reflector.

Claims (1)

[Claims] In a reduction projection type exposure apparatus, an alignment laser beam generation section and a laser beam emitted from the laser beam generation section are scanned around an alignment mark on a semiconductor wafer through a reticle and a reduction lens, and the reflected light is received through the reduction lens. A reduction projection type exposure apparatus comprising: a light receiving section that detects the position of the semiconductor wafer.