Chemical metrology on latent resist images

Abstract

Patterning photoresist with extreme control over dose and placement is the first crucial step in semiconductor manufacturing. However, how can the activation of modern complex resist components be accurately measured at sufficient spatial resolution? No exposed nanometre-scale resist pattern is sufficiently sturdy to unalteredly withstand inspection by intense photon or electron beams, not even after processing and development.This paper presents experimental proof that infrared atomic force microscopy (IR-AFM) is sufficiently sensitive and gentle to chemically record vulnerable yet valuable lithographic patterns in a chemically amplified resist after exposure prior to development. Accordingly, IR-AFM metrology provides long-sought insights into changes in the chemical and spatial distribution per component in a latent resist image, both directly after exposure and during processing. With these to-be-gained understandings, a disruptive acceleration of resist design and processing is expected.

Keywords

• Scanning probe microscopy
• IR-AFM
• Latent image
• Metrology
• Resist