KR20070059496A - Location measurement apparatus of stage and exposing equipment using the same - Google Patents

Abstract

An apparatus for measuring a position of a stage and exposure equipment using the same are provided to accurately measure position variation of a wafer stage by installing a light offsetting module between a polarizer and a polarized beam splitter. A polarizer(111) polarizes the light emitted from a light source(110). A polarized beam splitter(112) reflects or transmits the light passed through the polarizer. Reflectors(120,122) reflect the light reflected by or transmitted through the polarized beam splitter. A light offsetting module(116) is positioned between the polarizer and the polarized beam splitter to offset the light incident on the polarizer from the polarized beam splitter.

Description

Stage measurement apparatus of stage and exposing equipment using the same}

1 is a schematic diagram for explaining a conventional stage position measuring apparatus.

Figure 2 is a schematic diagram showing the configuration of a stage position measuring apparatus according to an embodiment of the present invention.

3 is a schematic view showing a configuration of an exposure apparatus according to an embodiment of the present invention.

** Description of the symbols for the main parts of the drawings **

100: stage position measuring device 110: light source

111 polarizer 112 polarization beam splitter

114: photodetector 116: optical offset module

118: 1/4 reflector 120: reference mirror

122: measurement mirror 124: right angle reflector (Corner cube)

130: wafer stage 200: exposure equipment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, to a stage position measuring apparatus and an exposure apparatus using the same, by accurately measuring the positional change of a wafer stage in a lithography process during a semiconductor manufacturing process to increase the overlapping alignment accuracy of the semiconductor exposure stage. To provide.

The stage positioning device is often used to accurately measure the relative displacement between two members, and also as a device for measuring the coordinates of the wafer stage or mask stage for highly precise positioning of the semiconductor wafer or reticle with respect to the fixed projection optics. do.

An apparatus for performing an exposure process includes a scanner, which is an exposure apparatus that transfers a pattern of a reticle onto a wafer surface coated with a photoresist during a semiconductor manufacturing process by scanning. The scanner repeatedly creates a reticle image on the wafer surface by exposing one die by unfolding a small slit-shaped image while moving the reticle and wafer surfaces simultaneously (4: 1 speed). .

The stage position measuring device can improve overlapping alignment accuracy by accurately measuring the position of the stage on which the semiconductor substrate is mounted and precisely controlling the movement thereof. The overlap alignment accuracy is the most important variable in the exposure step of the semiconductor device manufacturing process. Furthermore, as semiconductor devices are highly integrated and high precision is required, securing process margins of semiconductor devices due to high overlapping alignment accuracy is required.

There are various position measuring units such as heterodyne laser interferometer, He-Ne laser interferometer, and signal processing system for measuring the displacement of the object.The heterodyne laser interferometer is widely used because of its high measurement accuracy and long measuring range. However, He-Ne laser interferometer and signal processing system using separation effect are sold as commercial products.

The basic principle of the stage position measuring apparatus proposed in the prior art will be briefly described with reference to FIG. 1 is a schematic diagram illustrating a conventional stage position measuring apparatus 10.

The output beams from the light source 12 are polarized at right angles to each other by the polarizer 14 and divided into two light sources with a frequency difference of about 2 Mhz. Then in the polarizing beamsplitter 16 the two light sources are either reflected or transmitted.

If one of the two lights generated by the light source 12 is delayed and collected again, an interference fringe is generated due to the path difference between the two lights. The stage position measuring apparatus 10 using the laser is used because the coherence length of the laser is long, so that the optical interference fringes can be easily observed. Even the smallest changes can be measured.

First, since the light reflected by the polarization beam splitter 16 is returned to the optical path by the quarter wave plate 18 and the first reflection mirror 20, the polarization direction is rotated by 90 ° so that the polarization beam splitter 16 is rotated. ) Is penetrated in the linear direction and then enters the photodetector 30 through the linear polarizer 26. On the other hand, the beam passing through the polarization beam splitter 16 is again returned to the optical path by the quarter wave plate 22 and the second reflecting mirror 24, so that the polarization direction is rotated by 90 ° and the polarization beam splitter Reflected at 16 is also incident on photodetector 30 through line polarizer 26.

When the stage position measuring device 10 as described above is installed in a scanner device (not shown), and one of the reflection mirrors 20 and 24 of the position measuring device 10 is mounted on the wafer stage of the scanner device, the photodetector Since the interference fringe observed at 30 changes in accordance with the change in the position of the wafer stage, it is possible to read the change in position of the wafer stage by reading this as an electrical signal.

Basically, all the beams oscillated from the light source 12 must be received by the photodetector 30 to enable accurate position measurement of the wafer stage. However, when the residual beam 32 enters the light source 12 due to a manufacturing error of the polarization beam splitter 16 on the beam path of the stage position measuring device 10, the residual beam 32 and the light source 12 In this case, a collision with a newly oscillating beam occurs and noise is generated.

Accordingly, there is a problem in that a grid map measurement error of the wafer stage occurs, thereby reducing the degree of synchronization of the wafer stage.

The present invention has been made to overcome the disadvantages of the prior art as described above, stage position for canceling the light incident to the light source by mounting a light cancellation module that can remove the noise on the light path oscillated from the light source It is a technical problem to provide a measuring apparatus and exposure equipment using the same.

According to an aspect of the present invention for achieving the above object, the stage position measuring apparatus includes a light source, a polarizer for polarizing the light emitted from the light source, a polarizing beam splitter for reflecting or transmitting the light passing through the polarizer Reflecting units for reflecting light reflected or transmitted through the polarizing beam splitter, and an optical canceling module provided between the polarizer and the polarizing beam splitter to cancel light incident from the polarizing beam splitter to the polarizer.

Here, the optical canceling module may be an interferometer for allowing the light incident on the polarizer and the light oscillated on the polarizer to cancel each other.

The stage position measuring apparatus may further include a wafer stage disposed adjacent to the polarization beam splitter, wherein the reflectors are adjacent to the measurement mirror and the polarization beam splitter positioned between the wafer stage and the polarization beam splitter. The reference mirror may be disposed.

According to another aspect of the present invention, an exposure apparatus includes a light source, a blade positioned below the light source, a reticle positioned below the blade, an optical system positioned below the reticle, and a lower portion of the optical system. A second light source disposed adjacent to the wafer stage to measure a distance between the wafer stage and the optical system, and disposed between the second light source and the wafer stage and incident toward the second light source And an optical offset module for canceling the reflected wave.

The exposure apparatus may further include a reflector mounted on the optical system and the wafer stage, and a photodetector to which light reflected from the reflectors is incident.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey. On the other hand, the shape and the like of the elements in the accompanying drawings are preferably understood to be somewhat exaggerated for more clear description, the same reference numerals throughout the specification represent the same components.

2 is a schematic diagram showing the configuration of the stage position measuring apparatus 100 according to an embodiment of the present invention, Figure 3 is a schematic diagram showing the configuration of the exposure equipment 200 according to an embodiment of the present invention. First, referring to Figures 2 and 3, the configuration of the stage position measuring apparatus 100 according to an embodiment of the present invention will be described.

As shown in FIG. 2, the stage position measuring device 100 includes a light source 110, a polarizer 111, a polarization beam splitter 112, a photodetector 114, a light canceling module 116, and a rectangular reflector. Cube 124, quarter wave plates 118a and 118b, reference mirror 120, and measurement mirror 122. Optical components including the polarizing beamsplitter 112 are mounted on the optical support block 140. The optical support block 140 is preferably connected to the site or rigid structure of the exposure equipment.

The light irradiated from the light source 110 is polarized at right angles to each other by the polarizer 111 and divided into a reference light component 113 and a measurement light component 114 having a predetermined frequency difference, and the polarization beam splitter 112. ) To the side. The reference light component 113 has a polarization orientation parallel to the ground, and the measurement light component 114 has a polarization orientation perpendicular to the ground.

The polarization beam splitter 112 is optically aligned with the reference mirror 120, is interposed between the light source 110 and the reflectors 120 and 122, and has a polarization plane 112a positioned diagonally. It is composed of cubes. The polarization plane 112a divides the incident light of the measurement beam into the reference light component 113 and the measurement light component 114 and directs them in their respective travel paths.

The polarizing beam splitter 112 directs the reference light component 113 to the reference mirror 120 along the reference path, and directs the measurement light component 114 to the measurement mirror 122 along the measurement path. Generate a measurement interference pattern between (113, 114).

The quarter wave plates 118a and 118b are interposed between the polarizing beam splitter 112 and the reflectors 120 and 122, and the light components 113 and 114 are reflected by the reflectors 120 and 122. When it comes out, it passes through the quarter wave plates 118a and 118b twice so that the polarization orientation is rotated by 90 °.

The reference light component 113 is linearly polarized to pass through the polarization plane 112a of the polarization beam splitter 112 without reflection. The reference light component 113 is reflected back from the reference mirror 120 to the polarization beam splitter 112. In the movement path, the polarization phase of the beam is changed by 90 ° by passing through the polarization plane 112a without reflection and penetrating through the quarter wave plate 118b twice while being reflected back from the reference mirror 120. Thereafter, the light is rotated 180 ° through the right angle reflector 124 in the polarization plane 112a and then rotated 90 ° in the polarization plane 112a to face the photodetector 114.

The measurement light component 114 is vertically polarized to be reflected from the polarization plane 112a instead of passing through the polarization plane 112a of the polarization beam splitter 112. In the movement path, the polarization phase of the beam is changed by 90 ° by rotating 90 ° on the polarization plane 112a and penetrating the 1/4 wavelength plate 118b twice while being reflected back from the measurement mirror 122. Polarized. It then penetrates the polarization plane 112a and then through the rectangular reflector 124 again through the polarization plane 112a and back reflected by the measurement mirror 122 again. In this process, since the polarization phase is changed by 90 °, the beam is reflected by the polarization plane 112a and directed to the photodetector 114. Here, the measurement mirror 122 may be mounted on the wafer stage 130 disposed adjacent to the polarization beam splitter 112.

The photodetector 114 includes a polarizer and a photoelectric conversion element (not shown), and the polarization angle of the polarizer is set in a 45 ° direction with respect to the optical components 113 and 114 so that the photodetector 114 has the same direction among the optical components 113 and 114. Only vectors will pass. The photoelectric conversion element supplies the electric signal to a signal processing system (not shown) for photoelectric conversion after the vector components are incident to monitor the phase change. The signal processing system may analyze the supplied electric signal to determine the position of the wafer stage 130 with high precision.

The light canceling module 116 is interposed between the polarizer 111 and the polarization beam splitter 112 to transmit the light components 113 and 114 oscillated from the light source 110 as they are. In the case of the polarizing beam splitter 112, all the light components 113 and 114 reflected by the reflectors 120 and 122 must be incident on the photodetector 114. The people 113 and 114 are incident to the light source 110 again.

In this case, noise is generated by the collision between the light components 113 and 114 oscillated by the light source 110 and the residual beam 115 entering the polarizer 111 from the polarization beam splitter 112. It is difficult to accurately measure the position of the wafer W seated on the wafer stage 130. Therefore, since the optical cancellation module 116 blocks the residual beam 115 entering the polarizer 111, the generation of the noise may be prevented, thereby increasing the accuracy of the wafer W position detection.

Hereinafter, the interferometer may replace the optical cancellation module 116 to cancel the residual beam 115.

The conventional interferometer can know the relative position through the path difference using the constructive or destructive interference of the plurality of light components. In the present invention, since the residual beam 115 incident on the polarizer 111 must be canceled, a method by extinction interference is required. The light components 113 and 114 and the residual beam 115 are both derived from the same light source 110 and have the same wavelength. The residual beam 115 is reflected by the polarization beam splitter 112, the reflectors 120 and 122, the rectangular reflector 124, and the like, thereby decreasing its intensity.

Referring to the process of canceling, first, the wavelengths of the light components 113 and 114 and the residual beam 115 are arranged in a form in which the ridges and valleys face each other. Here, when the valleys of the wavelengths of the light components 113 and 114 and the valleys of the wavelengths of the residual beam 115 are opposed to each other, or the valleys of the wavelengths of the light components 113 and 114 and the valleys of the wavelengths of the residual beam 115 are opposed to each other. Since the intensity of the residual beam 115 is smaller than that of the light components 113 and 114, the wavelength of the residual beam 115 is canceled.

That is, the light canceling module 116 may be an interferometer 116 such that the residual beam 115 incident to the polarizer 111 is interfered with and canceled by the light components 113 and 114 oscillated from the polarizer 111. have.

Next, with reference to FIG. 3, the structure of the exposure apparatus 200 is demonstrated.

Since the exposure apparatus 200 includes the stage position measuring apparatus 100 as it is, the description thereof will be omitted, and other components will be briefly described.

The exposure apparatus 200 includes a wafer stage 130 including an exposure chuck (not shown) on which the wafer 132 is seated, a reticle stage 160 on which the reticle 162 is seated, and the reticle stage ( The optical system 150 is disposed between the 160 and the wafer stage 130 to reduce the light passing through the reticle 162 and project the light to the wafer 132.

In the exposure apparatus 200, the blade 170 focusing the light source 180, the reticle 160 having the circuit pattern, the optical system 150, and the wafer 132 are sequentially aligned. An exposure method using the exposure apparatus 200 performs exposure by irradiating light from the light source 180 on the upper portion of the reticle 160, while performing exposure while moving the wafer 132 and the reticle 160 in a predetermined direction. . At this time, the wafers 132 and the reticle 160 are the stages 130 and 160 on which they are placed, respectively, and the optical system 150 is fixed and does not move. As a result, the wafer 132 and the reticle 162 move with each other in a linear direction (Y-axis direction).

Here, the reference mirror 120 of the stage position measuring device 100 is mounted on the optical system 150, the measurement mirror 122 is mounted on the wafer stage 130 to measure the position of the wafer 132 Can be enabled.

The stage position measuring device and the exposure apparatus using the same are designed to overcome the disadvantages of the prior art as described above. In this way, since the positional change of the wafer stage can be accurately measured in the exposure step of the photolithography process, the overlapping alignment accuracy of the semiconductor exposure step can be increased.

Claims (5)

Light source; A polarizer for polarizing the light emitted from the light source; A polarization beam splitter for reflecting or transmitting light passing through the polarizer; Reflectors reflecting light reflected or transmitted through the polarization beam splitter; And And a light canceling module disposed between the polarizer and the polarizing beam splitter to cancel light incident from the polarizing beam splitter to the polarizer. The apparatus of claim 1, wherein the optical canceling module is an interferometer for canceling light incident on the polarizer and light emitted from the polarizer. The method of claim 1, further comprising a wafer stage disposed adjacent to the polarization beam splitter, wherein the reflectors are disposed adjacent to the measurement mirror and the polarization beam splitter positioned between the wafer stage and the polarization beam splitter. Stage position measuring apparatus comprising a reference mirror. Light source; A blade positioned below the light source; A reticle positioned below the blade; An optical system located below the reticle; A wafer stage provided below the optical system; A second light source disposed adjacent the wafer stage to measure a distance between the wafer stage and the optical system; And And an optical canceling module disposed between the second light source and the wafer stage to cancel the reflected wave incident toward the second light source. The exposure apparatus of claim 4, further comprising reflectors mounted on the optical system and the wafer stage, and a photodetector to which light reflected from the reflectors is incident.

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