Transmission mask with differential attenuation to improve ISO-dense proximity

• US 20060093971A1
• Filed: 12/16/2005
• Published: 05/04/2006
• Est. Priority Date: 02/11/2003
• Status: Active Grant

• Current Assignee: Infineon Technologies North America Corporation (Infineon Technologies AG), United Microelectronics Corporation
• Original Assignee: Infineon Technologies North America Corporation (Infineon Technologies AG), United Microelectronics Corporation
• Inventors: Schmidt, Sebastian, Liu, Hang Yip, Lin, Benjamin Szu-Min
• Granted Patent: US 7,807,342 B2
• Time in Patent Office: Days
• US Class Current: 430/394
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G03F 1/50 Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process

Abstract

An apparatus, system and method to compensate for the proximity effects in the imaging of patterns in a photolithography process. A light exposure of a photoresist layer is effectuated in predetermined patterns through an exposure mask having light-transmissive openings in correspondence to the predetermined patterns. The exposure mask has areas densely populated with the light-transmissive openings and areas sparsely populated with the light-transmissive openings. Light is attenuated through the densely populated light-transmissive openings by a different amount than through the sparsely populated light-transmissive openings.

Claims

1. A method of imaging patterns in a photolithography process, comprising:

effectuating a light exposure of a photoresist material to create therein a first pattern of features having a first feature density, including imposing a first amount of attenuation on light produced by a light source; and

effectuating a light exposure of the photoresist material to create therein a second pattern of features having a second feature density which differs from said first a feature density, including imposing on light produced by the light source a second amount of attenuation that differs from said first amount of attenuation.

2. The method of claim 1, wherein said first feature density is greater than said second feature density, and said first amount of attenuation is greater than said second amount of attenuation.

3. The method of claim 1, wherein all of the features of said first and second patterns are of substantially equal dimension.

4. The method of claim 1, including selecting said first amount of attenuation based on said first feature density, and selecting said second amount of attenuation based on said second feature density.

5. The method of claim 4, wherein said step of selecting said first amount of attenuation includes selecting said first amount of attenuation based also on a dimension desired for the features of said first pattern, and wherein said step of selecting said second amount of attenuation includes selecting said second amount of attenuation based also on a dimension desired for the features of said second pattern.

6. The method of claim 5, wherein the dimension desired for the features of said first pattern is equal to the dimension desired for the features of said second pattern.