Title:
OPTICAL HEIGHT METER, SURFACE-INSPECTION DEVICE PROVIDED WITH SUCH A HEIGHT METER, AND LITHOGRAPHIC APPARATUS PROVIDED WITH THE INSPECTION DEVICE
Document Type and Number:
WIPO Patent Application WO1998028661
Kind Code:
A3
Abstract:
A height meter for measuring the height of a first surface (1) of a transparent object (5) is described, which height meter comprises a radiation source for supplying a converging measuring beam (11) whose chief ray extends at an angle ( alpha ) to the normal on the surface, and a radiation-sensitive detection unit (30) for detecting a radiation beam (13) reflected by the surface (1) to be measured. Since a diaphragm (40) is arranged in the path of this beam (13), it is prevented that radiation (14) reflected by a second surface (3) situated opposite the first surface can reach the detection unit. The height meter is notably suitable for an inspection device for a lithographic mask (5). 00000
Inventors:
GREVE PETER FERDINAND
Application Number:
PCT/IB1997/001546
Publication Date:
August 13, 1998
Filing Date:
December 08, 1997
Export Citation:
Assignee:
PHILIPS ELECTRONICS NV (NL)
PHILIPS NORDEN AB (SE)
PHILIPS NORDEN AB (SE)
International Classes:
G01B11/02; G01B11/06; G01C1/00; G03F7/20; (IPC1-7): G03B/
Foreign References:
| GB1566398A | 1980-04-30 | |||
| US5359407A | 1994-10-25 | |||
| US3807870A | 1974-04-30 |
Other References:
PATENT ABSTRACTS OF JAPAN, Vol. 18, No. 159; & JP,A,05 332 769 (OOKURA IND KK) 14 December 1993.
PATENT ABSTRACTS OF JAPAN, Vol. 16, No. 12; & JP,A,03 231 103 (MIZOJIRI KOGAKU KOGYOSHO:KK) 15 October 1991.
PATENT ABSTRACTS OF JAPAN, Vol. 16, No. 12; & JP,A,03 231 103 (MIZOJIRI KOGAKU KOGYOSHO:KK) 15 October 1991.
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