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US 4,983,039 AGranted
Spectrometer
AssigneeHitachi, Ltd.
InventorsTatsuo Harada, Toshiei Kurosaki, Toshiaki Kita, Tsuneo Terasawa
Life of this patent
Estimating the term…
Abstract
A spectrometer is disclosed, in which plural entrance slits are mounted, and a reference light passing through one entrance slit and the light to be measured passing through the other entrance slit are simultaneously focused on a photo-sensitive surface of a detector through a diffraction grating and a focusing optical system, to measure the wavelength of the light to be measured precisely by using the reference light as a standard.
Claims32
A spectrometer, comprising:
- a first entrance slit for passing a reference light beam therethrough;
- a second entrance slit for passing a light beam to be measured therethrough;
- a combination of a diffraction grating and a focusing optical system for reflecting and diffracting at least a spectral line of both the reference light beam passing through the first entrance slit and the light beam to be measured passing through the second entrance slit, to focus the spectral lines of the reflected and diffracted reference light beam and the reflected and diffracted light beam to be measured;
- and
- linear image detection means for measuring the wavelength of the focused spectral line light beam to be measured by using the wavelength of the focused spectral line of the reference light beam as a standard.
2 more elements
The apparatus according to claim 18, wherein the combination of a diffraction grating and a focusing optical system simultaneously directs the spectral lines of the reference light beam and the beam to be measured simultaneously on the detection surface and the detection means measures these locations at the same time.
An excimer laser apparatus comprising:
- an excimer laser;
- a spectrometer for precisely measuring the wavelength of a radiation emitted from the excimer laser, and having
- a first entrance slit for passing a reference light beam therethrough,
- a second entrance slit for passing a light beam to be measured therethrough,
- a combination of a diffraction grating and a focusing optical system for reflecting and diffracting at least a spectral line of both the reference light beam passing through the first entrance slit and the light beam to be measured passing through the second entrance slit, to focus the spectral lines of the reflected and diffracted reference light beam and the reflected and diffracted light beam to be measured, and
- detection means for detecting the focused spectral line light beam to be measured and the focused reference light beam;
- and
- means for controlling the excimer laser on the basis of the measured wavelength of the radiation so that the wavelength of the radiation is always kept at a predetermined value.
5 more elements
A stepper comprising:
- a light source;
- a spectrometer for precisely measuring the wavelength of light emitted from the light source, and having
- a first entrance slit for passing a reference light beam therethrough,
- a second entrance slit for passing a light beam to be measured therethrough,
- a combination of a diffraction grating and a focusing optical system for reflecting and diffracting at least a spectral line of both the reference light beam passing through the first entrance slit and the light beam to be measured passing through the second entrance slit, to focus the spectral lines of the reflected and diffracted reference light beam and the reflected and diffracted light beam to be measured, and
- detection means for detecting the focused spectral line light beam to be measured and the focused reference light beam;
- means for controlling the light source on the basis of the measured wavelength of the light so that the measured wavelength of the light is always kept at a predetermined value;
- and
- a projector for forming an image of a mask pattern on a semiconductor substrate, light emitted from the light source and having a wavelength kept at the predetermined value being used as the exposure light of the projector.
6 more elements
A spectrometer, comprising:
- means for passing a light beam to be measured along a first path;
- means for passing a reference light beam of a different wavelength from the wavelength of the light beam to be measured along a second path in spaced relationship to the first path;
- optical means for focusing and diffracting at least respective spectral lines of the reference light beam and light beam to be measured simultaneously with a common diffraction grating and at least one common focusing optical element and to project the spectral images of the spectral lines simultaneously;
- detection means having a single detection surface;
- means for enlarging the projected spectral lines simultaneously and forming an enlarged spectral image of the spectral lines respectively spaced apart from each other on the single detection surface at the same time;
- and
- said detection means measuring the spaced apart distance between the spectral lines of the spectral image on the surface and producing a correlated difference signal corresponding to the difference in wavelength between the reference light beam and the light beam to be measured.
4 more elements
An apparatus for producing a stabilized light source, comprising:
- first light source for passing a reference light beam of a known stable wavelength;
- a second light source, separate from said first light source, for passing a light beam to be measured and controlled to stabilize its wavelength at a wavelength different from the wavelength of the reference light beam;
- a combination of a diffraction grating and a focusing optical system for reflecting and diffracting at least a spectral line of both the reference light beam and the light beam to be measured, with a diffraction grating common to both the reference light beam and the light beam to be measured;
- means establishing separate paths for the reference light beam and the light beam to be measured from their respective sources to the combination of a diffraction grating and a focusing optical system to thereby determine the angle of incidence of the light beam to be measured and the angle of incidence of the reference light beam to the diffraction grating in correlation to the difference in their wavelength so that the spectral lines of the reference light beam and the light beam to be measured have substantially the same angle of diffraction;
- and
- detector means for simultaneously receiving the spectral lines of the reference light beam and the light beam to be measured from the diffraction grating on a common surface and producing an output signal difference correlated to the difference in wavelength between the reference light beam and the light beam to be measured in response to the spacing between the spectral lines on the surface;
- and
- feedback means for controlling the wavelength of the light beam to be measured to stabilize the same in response to the difference signal.
5 more elements
Dependencies are inferred from the claim text.