Critical dimension (CD) uniformity of photoresist island patterns using alternating phase shifting mask

US10831104B2 · kind B2 · utility

Assignee

• TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD. · TW

Inventors

• Jesmin Haq · Milpitas, US
• Tom Zhong · Saratoga, US
• Zhongjian Teng · Santa Clara, US

Key dates

• Filing date: Dec 27, 2019
• Grant date: Nov 10, 2020
• Expiry date: Dec 27, 2039

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/01
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A photoresist film is patterned into an array of island shapes with improved critical dimension uniformity and no phase edges by using two alternating phase shifting masks (AltPSMs) and one post expose bake (PEB). The photoresist layer is exposed with a first AltPSM having a line/space (L/S) pattern where light through alternating clear regions on each side of an opaque line is 180° phase shifted. Thereafter, there is a second exposure with a second AltPSM having a L/S pattern where opaque lines are aligned orthogonal to the lengthwise dimension of opaque lines in the first exposure, and with alternating 0° and 180° clear regions. Then, a PEB and subsequent development process are used to form an array of island shapes. The double exposure method enables smaller island shapes than conventional photolithography and uses relatively simple AltPSM designs that are easier to implement in production than other optical enhancement techniques.