JPH06160015A - Optical measuring device - Google Patents

Abstract

PURPOSE:To reduce the noise due to the vibration of the atmosphere of the light path of the illumination of an optical measuring device. CONSTITUTION:The laser beam emitted from an He-Ne laser 7 is split into two beams by a first beam splitter 9 to irradiate the mirrors M1, M2 of X-and Y-stages net shown in a drawing and the interference fringes due to the reflected beams from the mirrors are measured by receivers 5, 6 to measure the positional shift of the X- and Y-stages. The fluctuation of one of the spilt beams is detected by a pickup 12 and the output of the pickup 12 is converted to an inverse phase by a phase shifter 13 to be inputted to an exciter 14 and the vibration of an inverse phase is applied to the vibration of an atmosphere generating fluctuation to attenuate the vibration of the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes the interference of illumination light such as laser light in a semiconductor exposure apparatus etc.
The present invention relates to an optical measuring device that measures displacement, deformation and the like.

[0002]

2. Description of the Related Art An optical measuring apparatus for measuring the length, shape, displacement, deformation, etc. of a distant object by utilizing the interference of illumination light such as laser light is a semiconductor exposure apparatus XY that requires high accuracy.
It is widely used for measuring the displacement of the stage.
Since the measurement accuracy of such an optical measuring device may be significantly reduced due to disturbances such as vibration and temperature change, the semiconductor exposure device is supported by a vibration isolator such as an air mount, and the whole is installed in a constant temperature chamber. However, it is common to prevent the temperature of the optical measuring device and its surroundings from changing by circulating the clean air kept at a constant temperature by the air conditioner.

[0003]

However, according to the above conventional technique, resonance occurs on the wall surface of the constant temperature chamber due to the vibration of the drive unit of the air conditioner installed in the constant temperature chamber and the flow of air at the air outlet. As a result, the air in the constant temperature chamber vibrates, causing fluctuations in the illumination light of the optical measuring device, and the fluctuations become noise in the measured values, significantly reducing the measurement accuracy of the optical measuring device.
Various noise detection and separation methods have been developed to detect such noise and separate it from the measurement value of the optical measurement device, but the device for detecting noise is expensive, and in addition, noise detection is performed. However, there is an unsolved problem that a sufficient accuracy cannot be obtained because a change in noise other than the sampling time required for the detection cannot be detected.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and it is possible to reduce noise due to vibration of the atmosphere such as air in the optical path of illumination light and improve the measurement accuracy. It is an object to provide an optical measuring device.

[0005]

In order to achieve the above object, an optical measuring device of the present invention is an optical measuring device for measuring an object by illuminating light with which the object is illuminated. The measuring means for measuring the vibration of the atmosphere of the optical path, and the vibrating means for applying the vibration for damping the vibration to the atmosphere based on the output of the measuring means.

[0006]

The vibration of the atmosphere such as air in the optical path of the optical measuring device is measured by the measuring means, and the vibration for damping the measured vibration is added to the atmosphere by the vibrating means.

[0007]

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

FIG. 1 illustrates a first embodiment. An optical measuring apparatus E ₁ of this embodiment is used for alignment of an XY stage of a semiconductor exposure apparatus (not shown) and is integrated with the XY stage. mirror M _1, irradiated with laser light is an illumination light to the respective M _2, the interferometer 1 of the reflected light of each mirror M _1, M ₂ is an object of the pair of rod-shaped mutually perpendicular that is provided, the 2 to obtain interference fringes. Interferometers 1 and 2
The interference fringes obtained by
Is introduced into the receivers 5 and 6 and the intensity change thereof is measured photoelectrically to detect the displacement of the mirrors M ₁ and M ₂ and measure the displacement of the XY stage.

The laser light applied to each of the mirrors M ₁ and M ₂ uses a He-Ne laser 7 or the like as a light source.
The laser light emitted from the Ne laser 7 is introduced into the first beam splitter 9 via the first beam bender 8,
The laser beam divided into two by the first beam splitter 9 passes through the second beam bender 10, the second beam splitter 11 and the interferometers ₁ and ₂ , respectively, and is reflected on the reflecting surfaces of the mirrors M ₁ and M _2. Is irradiated. The reflected light from the mirrors M ₁ and M ₂ is introduced into the interferometers 1 and 2, respectively, to obtain the aforementioned interference fringes.

In this way, the laser light applied to each of the mirrors M ₁ and M ₂ causes fluctuations due to the vibration of air, which is the atmosphere in the optical path, and becomes noise that deteriorates the measurement accuracy. In order to reduce this noise, a pickup 12 which is a measuring means for measuring the vibration of the air by detecting the fluctuation of the laser light incident from the first beam splitter 9 to the second beam splitter 11, and the pickup 12. A phase shifter 13 that converts the output signal of 12 into the opposite phase and a vibration exciter 14 that is a vibration unit that is driven by the output signal of the phase shifter 13 are provided. The output signal of the pickup 12 is converted into an opposite phase by the phase shifter 13 to drive the vibration exciter 14, and the driven vibration exciter 14 adds vibration of opposite phase that cancels the vibration to the air in the optical path. To do. As a result, the vibration of the air in the optical path is immediately attenuated, and the fluctuation of the laser light caused by the vibration disappears. Therefore, the detection values of the receivers 5 and 6 include noise due to the vibration of the air in the optical path of the laser light. That's not it.

FIG. 2 illustrates the second embodiment. The optical measuring device E ₂ of this embodiment is provided in the optical path of the laser light which is the illumination light with which the lens R which is the object to be measured is irradiated. The interferometer 21 and the TS lens 22 are provided, and the surface shape of the lens R is measured by the interference fringes obtained by the interferometer 21. The pedestal 23 that supports the interferometer 21, the TS lens 22 and the lens R is a measuring unit that measures the vibration of the air in the optical path by detecting the vibration of the air that is the atmosphere in the vicinity of the optical path. A pickup 24 is installed, and an output signal of the pickup 24 is passed through a phase shifter 25 which converts the output signal into an opposite phase, which is a vibrating means 2 which is a vibrating means.
Sent to 6. The vibration exciter 26 attenuates the vibration of the air measured by the pickup 24 by canceling the vibration of the air by adding the vibration to the air in the optical path. There is no possibility that noise will occur in the interference fringes of the total 21.

[0012]

Since the present invention is configured as described above, it has the following effects.

Noise due to vibration of the atmosphere in the optical path of the illumination light of the optical measuring device can be reduced. Therefore, even if vibration occurs in the atmosphere of the constant temperature chamber due to vibration of the air conditioner of the constant temperature chamber that accommodates the optical measuring device, it is possible to prevent the measurement accuracy of the optical measuring device from deteriorating due to noise due to the vibration. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a first embodiment.

FIG. 2 is an explanatory diagram illustrating a second embodiment.

[Explanation of symbols]

M ₁ , M ₂ mirror R lens 1,2,21 interferometer 3,4 total reflection mirror 5,6 receiver 7 He-Ne laser 12,24 pickup 13,25 phase shifter 14,26 exciter

Claims (3)

[Claims] 1. An optical measuring device for measuring an object by illuminating light with which the object is irradiated, the measuring means for measuring vibration of an atmosphere of an optical path of the illuminating light, and an output based on the output of the measuring means. An optical measuring device comprising: a vibrating unit that applies a vibration that attenuates the vibration to the atmosphere. 2. The optical measuring device according to claim 1, wherein the measuring means measures the vibration of the atmosphere by detecting the fluctuation of the illumination light. 3. The optical measuring device according to claim 1, wherein the measuring means measures the vibration of the atmosphere in the optical path by detecting the vibration of the atmosphere in the vicinity of the optical path of the illumination light. .