PAG and Quencher Effects on DBARC Performance

Abstract

Photosensitive Developable Bottom Anti-Reflective Coatings (DBARC) in the simplest form can be considered as a dyed photoresist. They need to function as a BARC material to address the issues due to the reflectivity from substrates and also be completely soluble in the developer after exposure, bake and develop steps of the photoresist. Hence, DBARCs possess the characteristics of both BARCs and photoresist materials. It is well known and very well documented that photoacid generators (PAGs) and quenchers play key roles in the chemically amplified resist formulations. Quantum efficiency, acid strength and diffusion length of the PAGs influence the resist sensitivity, resolution, exposure latitude, depth-of-focus, I-D bias, line-width roughness (LWR), line-edge roughness (LER), shelf-life, delay time and environmental stability of the photoresist. Similar to PAGs, quenchers also have direct impact on the resist performance mentioned above and they work in tandem. In photosensitive DBARCs as well PAGs and quenchers play crucial roles. In addition, the critical concentration of photogenerated acid needs to be maintained in the exposed areas of DBARC and photoresist for optimal performance. Since the photoresist and the DBARC polymers could have different cleave reaction activation energies, selection of PAGs and quenchers which does not easily intermix with photoresist is important to maintain the resist performance. Conversely, acid diffused or intermixed from the photoresist can also impact the DBARC performance. In this paper, effects of PAG and quencher type and amount, resist bakes and DBARC bakes on the photosensitive DBARC profiles are presented.