초록 ▼

A position detecting system suitable for the position control of the surface of a workpiece mounted in an electron beam exposure system is disclosed which includes an electrically-driven light source, a first optical system for focusing a light beam from the light source on a workpiece, a position-c

A position detecting system suitable for the position control of the surface of a workpiece mounted in an electron beam exposure system is disclosed which includes an electrically-driven light source, a first optical system for focusing a light beam from the light source on a workpiece, a position-controlling table for mounting thereon the workpiece, a second optical system for focusing light reflected from the workpiece on a predetermined image surface, a photodetector having a light receiving surface arranged on the image surface, and a negative feedback amplifier for controlling the light source by the output of the photodetector.

대표청구항 ▼

A system for detecting a height position of a workpiece suitable for use in an electron beam exposure apparatus which includes an electron beam source for forming an electron beam having a depth of focus in an evacuatable chamber and a movable table for supporting said workpiece to irradiate said wo

A system for detecting a height position of a workpiece suitable for use in an electron beam exposure apparatus which includes an electron beam source for forming an electron beam having a depth of focus in an evacuatable chamber and a movable table for supporting said workpiece to irradiate said workpiece with said electron beam, the system comprising: means for emitting a light beam to form a light spot on a surface of a workpiece, said light beam means including a light source for emitting said light beam and a stop for restricting said emitted light beam, said stop delimiting the diameter of said light spot on the surfaces of the workpiece to be smaller than or equal to nine times the depth of focus of the electron beam at a position on the surface; light detecting means having a detecting surface; optical means for focusing light reflected from the surface of the workpiece on said detecting surface of said light detecting means to form an image of said light spot thereon, said light detecting means generating a first signal related to an intensity of said light spot on said detecting surface and a second signal related to a position and the intensity of said light spot on said detecting surface; negative feedback means for feeding said first signal back to said light beam means to maintain constant the intensity of said light spot on said detecting surface; and circuit means for dividing said second signal with said first signal to form a third signal independent of the intensity of light on said detecting surface and indicative of the height position of the workpiece, whereby an accurate indication of the height position of the workpiece is obtained independently of variations in reflectivity of the surface of the workpiece or when different reflectivity surface portions of the workpiece are mixed together in the area of said light spot formed on the surface of the workpiece.