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US 6,603,533 B2Granted
Irradiation control method and apparatus for pulsed light source used in exposure apparatus
AssigneeNikon Corporation
InventorMasato Go
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AssigneeNikon Corporation
InventorMasato Go
Estimating the term…
A pulsed light source irradiation control method that irradiates a pulsed beam on an illumination subject includes the steps of measuring the energy of a pulsed beam having a predetermined oscillation frequency emitted from the pulsed light source, determining the actual oscillation frequency of the emitted pulsed beam in accordance with the number of pulses of the pulsed beam, and adjusting the energy of the pulsed beam when the actual oscillation frequency differs from the predetermined oscillation frequency.
An irradiation control method for a pulsed light source which irradiates a pulsed beam on an illumination subject, comprising the steps of:
An irradiation control apparatus which controls a pulsed light source that irradiates a pulsed beam on an illumination subject, comprising:
An exposure apparatus which irradiates a pulsed beam from a pulsed light source on a photosensitive substrate via a mask to expose a pattern of the mask on the photosensitive substrate, the exposure apparatus comprising:
An exposure method for irradiating a pulsed beam emitted from a light source on a photosensitive substrate via a mask to expose a pattern of the mask on the photosensitive substrate, comprising the steps of:
An exposure method for irradiating a pulsed beam emitted from a light source on a photosensitive substrate via a mask to expose a pattern of the mask on the photosensitive substrate, comprising the steps of:
A method of manufacturing an irradiation control apparatus that controls a pulsed light source which irradiates a pulsed beam on an illumination subject, comprising the steps of:
A method of manufacturing an exposure apparatus which irradiates a pulsed beam from a pulsed light source on a photosensitive substrate via a mask to expose a pattern of the mask on the photosensitive substrate, the method comprising the steps of:
A device manufacturing method comprising the steps of:
A device manufacturing method comprising the steps of:
A device manufactured by exposing a pattern of a mask onto a photosensitive substrate by irradiating an energy-adjusted pulsed beam by using the exposure apparatus including:
An exposure apparatus which irradiates a pulsed beam emitted from a light source on a photosensitive substrate via a mask to expose a pattern of the mask on the photosensitive substrate, comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Production of exposure light, i.e. light sources: by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption: dose control, i.e.…
Photomechanical production of textured or patterned surfaces
Term ended 26 Nov 2018 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates to an irradiation control method and irradiation control apparatus for a pulsed light source for irradiating a pulsed beam on an illumination subject. More specifically, the present invention relates to an irradiation control method and irradiation control apparatus for a pulsed light source for an exposure apparatus which is used in photolithography process for fabricating a micro device, such as a semiconductor device, a liquid crystal display device, an image pickup device (CCD or the like) or a thin-film magnetic head.
Conventionally, fabrication of devices, such as semiconductor devices, uses an exposure apparatus which transfers and exposes the pattern of a reticle as a mask on a wafer (or a glass plate) on which a photosensitive material, such as a photoresist, is coated. The recent miniaturization of circuit patterns demands that such an exposure apparatus have a higher resolution. A high resolution may be acquired by shortening the wavelength of exposure light or increasing the numerical aperture (N.A.) of a projection optical system. Increasing the numerical aperture of the projection optical system however makes the depth of focus shallower. Therefore, a practical solution is to employ, for example, an excimer laser which has a short wavelength.
When an excimer laser is used as a pulsed light source, the integrated amount of exposure may vary from one point to another in each shot area on a wafer. At the time of exchanging a wafer or at the time of measuring alignment of a reticle, wafer or the like, for example, the emission interval of laser beams becomes long. In such a case, laser learning control is halted such that the state of the gas in the laser chamber, for example, differs from that at the time of the last laser emission before the halt. As a result, the laser beam output varies. The energy of the pulsed beam emitted from the pulsed light source may go significantly above or below the set energy until the pulsed light source returns to a stable oscillation state since the initiation of emission of the laser beam.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
FIG. 1 is a schematic diagram illustrating the structure of a scanning exposure apparatus according to first and second embodiments;
FIG. 2 is a schematic block diagram of an excimer laser light source for the exposure apparatus in FIG. 1;
A first embodiment of the present invention will now be described with reference to FIGS. 1 through 4. FIG. 1 illustrates the schematic structure of a scanning exposure apparatus 10 of a step and scan type according to the first embodiment. This scanning exposure apparatus 10 uses an excimer laser as a pulsed light source for exposure.
The scanning exposure apparatus 10 has an illumination optical system 12, a reticle stage (mask stage) RST that moves in a predetermined scanning direction while holding a reticle (mask) R which is illuminated by the illumination optical system 12, a projection optical system PL which projects the pattern of the reticle R on a wafer W, an XY stage 14 which moves on a horizontal plane (within the XY plane) while holding the wafer W, and a main controller 50.
The illumination optical system 12 has an excimer laser light source 16, a beam shaping optical system 18, a rough energy adjuster 20, a fly eye lens 22, an illumination-optical-system aperture stop plate 24, a beam splitter 26, a first relay lens 28A, a second relay lens 28B, a fixed reticle blind 30A, a movable reticle blind 30B, a mirror M for deflecting the optical path and a condenser lens 32.