JPH04112522A - Aligner - Google Patents

Abstract

PURPOSE:To detect a focal-point position and to conduct the levelling of a substrate by a method wherein a single part is irradiated with beams of light from a plurality of directions and the output electric signals of reflected beams of light detected corresponding to independent photodetection positions are processed mathematically. CONSTITUTION:Beams of light emitted from a plurality of LED's 10 are changed to parallel beams of light by using collimator lenses 9; the parallel beams of light are frequency-modulated by using amplitude modulators 8; after that, a substrate 1 is irradiated with the beams. A single part on the substrate 1 is irradiated with the light fluxes; respective reflected beams of light are photodetected by using condensing lenses 6 corresponding to independent photodetection positions; the condensed beams of light are photodetected by using photodetectors which output electric signals. Then, the signals of the individual photodetectors are processed mathematically, such as averaged or the like. By using this result, a focal-point position is detected, the substrate is leveled and the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exposure apparatus that performs overlapping in a photolithography process, and particularly relates to an exposure apparatus that improves leveling for correcting wafer inclination. be.

[Conventional technology]

Focusing over the entire exposure field after resist coating on a wafer, which is a semiconductor substrate, is important for improving product yield and reliability. That is, the projection lens has a high NA (Numerical Aperture:
As the numerical aperture becomes larger (numerical aperture) and the exposure wavelength becomes shorter, the depth of focus becomes smaller, and there is practically insufficient margin for focusing over the entire exposure field. Due to the inclination in the exposure field region due to surface irregularities, etc., the margin for focusing becomes increasingly insufficient.For this reason, leveling is usually performed to correct the inclination of the wafer.

FIG. 2 is a diagram of a conventional leveling mechanism that performs this type of leveling. This one is leveling stage 2
Light is emitted from a light source lO onto the upper substrate l, which is converted into parallel light by a collimator lens 9 and then irradiated. This light beam is reflected on the substrate 1 and focused onto the position detection element 7 by the condenser lens 6. The inclination on the substrate 1 is measured as a positional shift of the light spot on the position detection element 7.

[Problem to be solved by the invention]

A conventional exposure apparatus is configured as described above, and the substrate 1
Part of the light irradiated onto the substrate 1 is scattered due to the unevenness on the substrate 1, and the positional deviation of the light spot on the position detection element 7 becomes different from that when there is no scattering.

As a result, the leveling of the substrate 1 cannot be performed sufficiently, and the focusing margin for exposure becomes practically insufficient.

Therefore, problems such as a decrease in product yield and a loss of reliability arise.

The present invention has been made to solve the above-mentioned problems, and aims to provide an exposure apparatus that can improve product yield and reliability.

[Means to solve the problem]

The exposure apparatus according to the present invention irradiates light from multiple directions to a single location, and performs mathematical processing such as averaging the signals of the light receiving elements that output electric signals corresponding to independent light receiving positions of each reflected light. The results are used to detect the focal point position, level the substrate, etc.

Further, one signal having the highest intensity among the signals of each of the above-mentioned light receiving elements is selected to perform focal position detection, substrate leveling, etc.

[Effect]

In the present invention, by having the configuration as described above,
Since light is irradiated to a single location from multiple directions, the influence of reflected light on positional deviation can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a leveling mechanism of an exposure apparatus according to a negative embodiment of the present invention. In the figure, l is the substrate, 2
3 is a leveling stage, 3 is a stage driving point, 4 is a stage fixing point, 5 is an irradiation area, 6 is a condensing lens, 7 is a position detector, 8 is a modulator, 9 is a collimator lens, and 10 is an LED light.

Next, the operation will be explained. The light emitted from the plurality of LEDs 10 is made into parallel light by a collimator lens 9, frequency modulated by an amplitude modulator 8, and then irradiated onto the substrate 1. This light flux illuminates a single spot on the substrate 1, and each reflected light is received by a condenser lens 6 corresponding to an independent light receiving position, and the condensed light is sent to a light receiving element that outputs an electrical signal. Let it receive light.

Next, the signals of each light receiving element are subjected to mathematical processing such as averaging, and the results can be used to perform focal position detection, leveling of the substrate, etc.

In the above embodiment, the signals of each light receiving element are subjected to mathematical processing such as normal distribution, and one of the normal distributions of signals of each light receiving element with the highest intensity is selected to detect the focal position and to horizontally align the substrate. In this case, the light receiving position corresponding to each light emitting position may be modulated so that other light receiving positions are not affected by the influence of each light scattering shown in the above embodiment. The container 8 can be made unnecessary.

〔Effect of the invention〕

As described above, according to the exposure apparatus according to the present invention, since light is irradiated onto a single location on the wafer from multiple directions, the influence of reflected light on positional deviation can be reduced, and leveling can be performed accurately. Is possible.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing the state of an exposure apparatus according to the present invention, and FIG.
The figure shows the state of a conventional exposure apparatus. In the figure, l is the substrate, 2 is the leveling stage, 3 is the stage driving point, 4 is the stage fixing point, 5 is the irradiation area, 6 is the condensing lens, 7 is the position detector, 8 is the modulator, and 9 is the collimator lens. , lO is an LED light. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A means for irradiating light onto a single spot on a wafer from multiple directions, a light-receiving element that receives each reflected light at an independent light-receiving position and outputs an electrical signal, and a mathematical method for the signal of each light-receiving element. 1. An exposure apparatus comprising means for performing mathematical processing, and detecting a focus position and leveling a substrate using the results of the mathematical processing. (2) means for irradiating light onto a single spot on the wafer from multiple directions; a light receiving element for receiving each reflected light at an independent light receiving position and outputting an electrical signal; It is characterized by comprising means for performing mathematical processing to obtain the distribution and selecting one of the signals of the light-receiving element with the highest intensity, and using the selected signal to detect the focal point position and level the substrate. Exposure equipment.