Substrate-Effect of Chemically Amplified Resist.

Abstract

SiN, Bare Si, and Si02 substrate-effects in chemically amplified (CA) resist have been investigated by surface analysis and evaluating the pattern profile of CA negative tone resist. It is considered that substrate-effects are distinguished from adhesion, optics and substrate components. It is found that the undercut profile of negative tone resist on SiN substrate can not be due to adhesion and optics. Fine profile can be replicated on SiN substrate treated with oxygen plasma optimized condition. Undercut profile can not be affected mainly by adsorbed materials on SiN substrate from Thermal Desorption Spectroscopy (TDS) analysis results. From the results of Electron Spectroscopy for Chemical Analysis (ESCA), it is found that SiN bonding is replaced to Si-0 bonding while SiN substrate is treated with oxygen plasma. The pattern profile on SiN substrate by oxygen plasma treatment is improved by the thin Si02 layer formed on SiN substrate. Relations between footing length and oxygen plasma treatment condition suggest that undercut profile is caused by the atom content of nitrogen on the surface of SiN substrate. Excessive oxygen plasma treatment of SiN substrate occurs the footing profile for the negative tone resist because of surface damage. At the interface between the SiN substrate and the CA resist, the SiN substrate works as base existing H2O, and quenches photogenerated acids. Additionally, it is considered that the NHS on SiN substrate quenches the photo-generated acids directly. The mechanism of substrate-effect is clarified.

Hard Mask Process Using Chemically Amplified 157-nm Resists.

“…There was no significant difference in reflectivity between an SiN thickness of 70 nm and 100 nm. BARC also worked to prevent the expected tapered profile often observed at the bottom of a resist fabricated on some inorganic films [15][16]. Therefore, we applied DUV42 (at a thickness of 30 nm), which showed good compatibility with F-resist A-C and a relatively high etching rate, as an organic BARC on SiN.…”

Effect of Substrate Treatments on Resist Footing in Chemically Amplified System.

“…are catalyst scavengers in chemically amplified resists [4,7]. To evaporate H2O and NH3, we baked the substrate at 500 t in a vacuum (vacuum pressure was less than 10E-5 torr).…”

“…It was reported that the resist footing in negative chemically amplified resist on SiN derived from roughness [4]. We measured root mean roughness (from AFM) for samples ( table 1).…”

“…Since chemically amplified resists use a catalytic reaction, they are very susceptible to any loss of acid [1,2]. This loss causes, resist footing and resist undercutting on several substrates like SiN [3,4,5], TiN [5]and others [6,7]. Many researchers have reported how to improve resist profiles by using substrate treatments and/or by using a barrier layer between a substrate and a resist.…”

Effect of substrate heating treatment on pattern profile in Chemically Amplified(CA) resist process.

“…It is apparent that factors, such as profile, exposure latitude and CD reliability are important criteria for using the CA resist in device mass-production. But these are not near completion because the CA resist has some problems due to atmospheric or substrate contamination [2][3][4]. Many empirical and laborious approaches to improve the contamination susceptibility of resist processes have been attempted, such as chemical filters for improving the environmental air [5-b], an overcoat film for sealing from environmental contamination [7][8], and modification of the resist itself [9][10].…”