Charged particle beam exposure system and method of compensating for eddy current effect on charged particle beam

Patent 4891524 Issued on January 2, 1990. Estimated Expiration Date:

September 12, 2008. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3922546

Scanning electron microscope with eddy-current compensation
Patent #: 4125772
Issued on: 11/14/1978
Inventor: Holmes

Compensated magnetic deflection coil for electron beam lithography system
Patent #: 4251728
Issued on: 02/17/1981
Inventor: Pfeiffer , et al.

Electron beam exposure system and an apparatus for carrying out the same
Patent #: 4362942
Issued on: 12/07/1982
Inventor: Yasuda

Automatic focus and deflection correction in E-beam system using optical target height measurements
Patent #: 4468565
Issued on: 08/28/1984
Inventor: Blair , et al.

Variable axis immersion lens electron beam projection system
Patent #: 4544846
Issued on: 10/01/1985
Inventor: Langner , et al.

Charged particle beam apparatus Patent #: 4701623
Issued on: 10/20/1987
Inventor: Beasley

Inventors

Yasuda, Hiroshi
Suzuki, Masahiko (deceased): ; , ;

Application

No. 243274 filed on 09/12/1988

US Classes:

250/398, With target means250/396MLMagnetic lens

Examiners

Primary: Anderson, Bruce C.

Attorney, Agent or Firm

Staas & Halsey

Foreign Patent References

0148784 EP. 07/19/1985

International Class

H01J 037/04

Foreign Application Priority Data

1987-09-16 JP

Abstract

A method for compensating for an eddy current effect due to leakage flux of a magnetic lens in a charged particle beam exposure system, and a system for exposing the beam on a substrate while a stage carrying the substrate is moving. By employing this method and system, a step and repeat system can be operated while the stage is moving, while improving the throughput of the system. A deviation in the path of the charged particle beam caused by the eddy current is proportional to the velocity of the stage. To compensate for this, a proportional constant relating the deviation to the velocity of the stage is measured in advance, and a correction term which is a product of the speed of the stage and the proportional constant, is fed back to a deflector of the charged particle beam. The proportional constant is obtained from a shift of an image of a test pattern viewed on a CRT in a SEM mode, from a first position at which the stage is stationary to a second position while the stage is moving at a constant speed.

Other References

Journal of Vacuum Science & Technology B, Microelectronics Processing and Phenomena, vol. 5, 1987, American Vacuum Society, "A High Dose and High Accuracy Variable Shaped Electron Beam Exposure System for Quartermicron Device Fabrication", by Yoshikawa et al, pp. 70-7