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US 7,460,210 B2Granted
Auto focus system, auto focus method, and exposure apparatus using the same
AssigneeSamsung Electronics Co., Ltd.
InventorDong-Woon Park
Life of this patent
Estimating the term…
Abstract
An auto focus system includes a stage on which a substrate is mounted, light sources that irradiate the substrate with a plurality of focus beams directed towards the substrate at different angles, sensors that detect the focus beams reflected from the substrate, and a controller that determines the relative location of a surface of the substrate according to the locations at which the focus beams are detected by the sensors and positions the substrate accordingly. To this end, the controller performs calculations that are free from the influence of variations in the refractive index of the medium through which the focus beams propagate to the surface of the substrate. Therefore, the autofocus process is carried out with a high degree of precision.
Claims20
An auto focus system comprising:
- a stage to which a substrate is to be mounted;
- optical components including measuring light sources each of which emits a focus beam, and sensors each operative to output a signal indicative of a location at which a beam of light of the type emitted by the light sources is received thereon,
- the optical components being arranged to direct the focus beams emitted by the measuring light sources at different angles, respectively, towards a substrate mounted on the stage, wherein the angle at which the focus beam propagates towards the substrate mounted on the stage is defined as the angle subtended between the focus beam and a plane that is parallel to an upper surface of the stage, and
- such that the sensors receive the focus beams reflected from the substrate such that the sensors will output signals indicative of locations at which the reflected focus beams are received thereon;
- and
- control means operatively connected to said sensors so as to receive the signals output by the sensors, the control means comprising a calculation unit configured to incorporate together values representing the relative locations from which the focus beams emanate from the light sources, with values representing the angles at which the focus beams propagate towards the substrate, and with values representing the locations at which the reflected focus beams are received on the sensors, respectively, and thereby calculate a focus changing value indicative of the position of a surface of a substrate mounted to the stage relative to a reference plane, and the control means operatively connected to the stage so as to control the position of the stage based on the focus changing value.
3 more elements
An auto focus method comprising:
- aiming several focus beams at different angles, respectively, towards a substrate and thereby irradiating the substrate with the focus beams, wherein the angle at which each focus beam is aimed towards the substrate is the angle subtended between the focus beam and a plane that is parallel to the plane of the substrate;
- detecting locations to which the focus beams are reflected from the substrate, respectively, and assigning values to the locations;
- incorporating together values representing the relative locations from which the focus beams are aimed towards the substrate, values representing the different angles at which the focus beams propagate towards the substrate, and the values assigned to the locations at which the reflected focus beams are detected, respectively, and thereby calculating a focus changing value indicative of the height of a surface of a substrate relative to a reference plane, and
- controlling the position of the substrate according to the focus changing value.
1 more element
An immersion exposure apparatus comprising:
- a light source;
- a stage to which a substrate is to be mounted;
- an optical system interposed in the apparatus between the light source and the stage so as to project light emitted by the light source onto a substrate mounted to the stage;
- and
- an auto-focus system comprising optical components including measuring light sources each of which emits a focus beam, and sensors each operative to output a signal indicative of a location at which a beam of light of the type emitted by the light sources is received thereon,
- the optical components being arranged to direct the focus beams emitted by the measuring light sources at different angles, respectively, towards the substrate mounted on the stage, wherein the angle at which the focus beam propagates towards the substrate mounted on the stage is defined as the angle subtended between the focus beam and a plane that is parallel to an upper surface of the stage, and
- such that the sensors receive the focus beams reflected from the substrate such that the sensors will output signals indicative of locations at which the reflected focus beams are received thereon, and
- control means operatively connected to the sensors so as to receive the signals output by the sensors, the control means comprising a calculation unit configured to incorporate together values representing the relative locations from which the focus beams emanate from the light sources, values representing the angles at which the focus beams propagate towards the substrate, and values representing the locations at which the reflected focus beams are received on the sensors, respectively, and thereby calculate a focus changing value indicative of the position of a surface of the substrate mounted to the stage relative to a reference plane, and the control means operatively connected to the stage so as to control the position of the stage relative to the optical system based on the focus changing value.
5 more elements
Dependencies are inferred from the claim text.