A novel switchable BARC (SBARC) and process to improve pattern collapse and defect control

Abstract

To optimize the anti-reflectant material (BARC) in 193nm resist processes requires a careful manipulation of the surface energy of the BARC. In general, the surface energy of the BARC is constant in the unexposed and exposed areas. We have developed a new material with a "switchable" contact angle (SBARC) whose key criteria are as follows: (1) High contact angle at about 70 degrees in the unexposed areas under the resist to prevent developer and water penetration; (2) Maximized adhesive of the SBARC to the resist. (3) Contact angle less than 50 degrees in the exposed areas at the BARC surface to reduce the density of satellite-type defects. The low contact angle in the exposed areas reduces the adhesive forces between the hydrophobic resist residues and the more hydrophilic SBARC surface and thus lowers defects.In addition, the hydrophilic SBARC surface can reduce water drop residues and therefore reduce watermark defects. This paper will also describe our process work to optimize the contact angle of unexposed and exposed BARC surface to reduce pattern collapse and minimize satellite defects. We will also discuss a few methods to improve the surface condition of the SBARC to maximize adhesive forces.Further optimization of the develop process and the refractive index and the absorption coefficient of the SBARC, will provide even better collapse margin for 193-nm resists than the present baseline.

Pattern collapse mitigation by controlling atmosphere during development process for semiconductor lithography

“…A similar phenomenon is considered to have occurred during the rinsing process. [32][33][34] The proposed method is considered to be promising, because it requires no chemical additive, [7][8][9] no additional process, 14,19,20) and no special equipment such as a high pressure vessel. [10][11][12]…”

“…17,18) The use of underlayers is effective to prevent the pattern collapse by increasing the adhesion force. 19,20) The effects of the developer on the pattern collapse have also been reported. 21,22) In this study, we focused on the differential pressure for the mitigation of pattern collapse.…”