Optical exposure method

• US 5,465,220 A
• Filed: 06/01/1993
• Issued: 11/07/1995
• Est. Priority Date: 06/02/1992
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tanaka, Hiroyuki, Taguchi, Masao, Asai, Satoru, Nakagawa, Kenji, Hanyu, Isamu, Haruki, Tamae
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US08/069,853
• Time in Patent Office: 889 Days
• Field of Search: 364/525, 364/DIG. 1, 364/224.7, 430/5, 430/320, 430/321, 395/800
• US Class Current: 347/256
• CPC Class Codes: G03F 7/201 characterised by an oblique exposure; characterised by the use of plural sources; characterised by the rotation of the optical device; characterised by a relative movement of the optical device, the light source, the sensitive system or the mask
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/701 Off-axis setting using an aperture
• CPC Class Codes: G03F 7/70125 Use of illumination settings tailored to particular mask patterns details of setting means G03F7/70091
• CPC Class Codes: G03F 7/70241 Optical aspects of refractive lens systems, i.e. comprising only refractive elements
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70566 Polarisation control
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting

Abstract

An optical exposure method in photolithography applied for precise processing when semiconductor devices are produced. A pattern on a photomask is projected and exposed on a register on a base plate with an exposure device including a deformation illumination system, a photomask and a projection lens. The deformation illumination system is composed of a light source, a diaphragm and a condenser lens, and the diaphragm is provided with a linear through-hole. The optical exposure method uses a ray of linear light for illumination or two rays of linear light for illumination that are parallel with the pattern. The two rays of linear light are symmetrical with respect to an optical axis. These rays are parallel with the pattern in a position separate from the optical axis of the exposure device when the photomask pattern is a line and space pattern.

Claims

1. An optimization method for a light source profile in an optical exposure apparatus including a light source having a light source surface of a predetermined irradiation area, an illumination lens, a photomask having a predetermined mask profile, a projection lens and a device substrate, wherein a light from said light source is irradiated on to said photomask through said illumination lens, said light passing through said photomask is exposed on said device substrate through said projection lens to form a device profile on said device substrate, said optimization method comprising the steps of:

dividing said light source surface into a predetermined number of blocks, so that a point light source corresponding to each divided block is a processing element of optimization processing;

converting said respective processing element into binary information;

varying a value of said processing element by the predetermined number of the blocks in accordance with the conditions of said device profile, said mask profile, optical parameter and optimization parameter; and

conducting optimization combination processing to determine the light source profile, until a predetermined evaluation judgement condition is obtained.

2. The optimization method for a light source profile according to claim 1, wherein said optimization combination processing is a simulated annealing method.

3. The optimization method for a light source profile according to claim 1, wherein said optimization combination processing is carried out in such a manner that:

optical intensity is determined for each pair of point light sources symmetrical with respect to an optical axis;

said pair of point light sources are successively adopted from one, a focal depth of which is largest, until a predetermined illumination can be provided.

4. An optimization method for a light source profile in an optical exposure apparatus including a light source having a light source surface of a predetermined irradiation area, an illumination lens, a photomask having a predetermined mask profile, a projection lens and a device substrate, wherein a light from said light source is irradiated on to said photomask through said illumination lens, said light passing through said photomask is exposed on said device substrate through said projection lens to form a device profile on said substrate, said optimization method comprising the steps of:

dividing said light source surface into a predetermined number of blocks, so that a point light source corresponding to each divided block is a processing element of optimization processing;

converting said processing element into binary information;

inputting conditions of a device profile, mask profile, optical parameter and optimization parameter;

generating a sampling point for evaluating said processing elements;

registering ideal optical intensity data as teaching data for each sampling point; and

selecting a combination or said processing elements to determine an evaluation function of the combination, so that a light source profile is determined by varying the combination of said processing elements until said evaluation function obtains a predetermined evaluation judgement condition.

5. The optimization method for a light source profile according to claim 4, wherein said optimization combination processing is a simulated annealing method.

6. The optimization method for a light source profile according to claim 4, wherein said optimization combination processing is carried out in such a manner that:

optical intensity is determined for each pair of point light sources symmetrical with respect to an optical axis;

said pair of point light sources are successively adopted from one, a focal depth of which is largest, until a predetermined illumination can be provided.