公开(公告)号：DE2965298D1

公开(公告)日：1983-06-01

申请号：DE2965298

申请日：1979-10-31

Applicant: IBM

Inventor： GASTON CHARLES ARDEN ,  KIRK JOSEPH PENNELL ,  WASIK CHESTER ALEXANDER

IPC: G01B11/06

Abstract: An optical system and technique for monitoring a monotonic change in the thickness of a transparent film by means of optical interference, and for eliminating ambiguity in the identification of absolute film thickness. The system is particularly adapted for monitoring the etching of a dielectric film of uncertain initial thickness in microelectronic fabrication. The technique utilizes a white light source directed upon the film. Reflected light, modified by optical interference in the dielectric film, is monitored by photodetectors at two distinct wavelengths. The cyclic patterns of intensity change at the two wavelengths are compared to identify unambiguously the absolute thickness of the film, although the initial uncertainty in film thickness may have corresponded to several cycles of either wavelength pattern alone. To simplify phase comparison of the two cyclic patterns, wavelengths can be selected so that some particular coincidence of extrema in the two signals occurs at a film thickness less than the expected minimum initial thickness, and does not occur at any greater thickness up to and including the expected maximum. Determination of the absolute film thickness in this way permits further tracking of the etching process to the desired end point without overshoot.

公开(公告)号：DE3582404D1

公开(公告)日：1991-05-08

申请号：DE3582404

申请日：1985-11-12

Applicant: IBM

Inventor： BEUMER KARL WILLI ,  GASTON CHARLES ARDEN ,  MACK ALFRED ,  O'NEILL BRIAN COLLINS ,  PINCKNEY WARREN JOHN ,  LOCKE CHARLES HENRY ,  WILSON ALAN DICKSON

IPC: H01L21/30 ,  H01J37/20 ,  H01L21/027 ,  H01L21/68 ,  H05K13/02 ,  H01L21/00

Abstract: A high precision, high throughput submicrometer workpiece positioning system, particularly useful as a workpiece positioning means in electron beam lithography tools. The positioning system increases mechanical stability by essentially eliminating mechanical hysteresis, which allows state of the art electron beam lithography systems to provide the repeatable, accurate and dense circuit patterns that modern semiconductor trends demand.The positioning system comprises a movable positioning table (12), a workpiece supporting superstructure (14) which is elastically joined to the movable positioning table (12) by three geometrically distinct kinematic support means (16. 18, 20) and a two-stage coupling means (24) which mounts a workpiece (32) (i.e., semiconductor mask or wafer) to the workpiece supporting superstructure (14). A laser interferometer locating-positioning system is utilized to position the workpfece. The interferometer mirrors (28) are integral with the workpiece supporting superstructure (14).The coupling means (24) mounts a workpiece (22) to the workpiece supporting superstructure (14) with a minimum of mechanical distortion. Three two-stage coupling means (24) are utilized in preferred form. The first stage (34) is removable from the positioning, and allows for workpiece loading and unloading outside of the positioning system. The removable stage (34) comprises an integral unit (33) which includes two opposing arms (42, 44) with large radii spherical ends and a tab member. The spherical end center lines are collinear, providing for vertical clamping of the workpiece (32). The second stage (36) is stationary and integral with the workpiece supporting superstructure (14). The stationary stage (36) comprises two opposing arms (38, 40) with large radii spherical ends and clamps the tab (46) of the removable stage by verticai clamping.