An E-Beam Direct Write Process For Half Micron DRAMS

Noboru Nomura; Kenji Kawakita; Toshihiko Sakashita; Kenji Harafuji; Toyoki Takemoto

doi:10.1117/12.945662

Abstract

Direct write electron beam (EB) lithography is expected to write a very fine wafer pattern below half micron for the development of the comming generation ULSIs. But direct write EB lithography has two main peculiar problems for obtaining such a very fine resist pattern on an uneven topography of a processed wafer. One is a pattern dimension deviation from the designed value due to resist topography and proximity effects. The other problem is pattern registration deviation due to charge-up in the EB-resist. In order to investigate the proximity effect. we evaluated the deposited energy density profile by a double gaussian Exposure Intensity Distribution ( EID ) function. The theoretical and experimental results showed that in a 2.2 micron thick trilayer planerizing resist system. both 0.5 micron isolated line and isolated space were simultaneously resolved in half micron thick top layer resist. To compensate the charge-up problem, we treated the bottom-layer by a brand-new ion shower material modification process. A 40 KV proton shower irradiation decreased the resistance of the bottom layer. The charge of the electron beam was dissipated through the bottom layer resist. The resultant half micron rule 16 M-bit DRAM patterns were compared with the optically exposed tri-level resist patterns. The optically exposed patterns also had an optical proximity effect and half micron patterns were not resolved even adopting the contrast enhancement lithographic ( CEL ) technology. On the other hand, we successfully obtained 16M-bit DRAM patterns on the uneven topography of the processed wafer using EB direct write.

Citation Download Citation

Noboru Nomura, Noboru Nomura, Kenji Kawakita, Kenji Kawakita, Toshihiko Sakashita, Toshihiko Sakashita, Kenji Harafuji, Kenji Harafuji, Toyoki Takemoto, Toyoki Takemoto, "An E-Beam Direct Write Process For Half Micron DRAMS", Proc. SPIE 0923, Electron-Beam, X-Ray, and Ion Beam Technology: Submicrometer Lithographies VII, (14 June 1988); doi: 10.1117/12.945662; https://doi.org/10.1117/12.945662

ACCESS THE FULL ARTICLE

PERSONAL SIGN IN
Full access may be available with your subscription

Email or Username Forgot your username?

Password Forgot your password?

Show

Remember Email/Username on this computer

Remember Password

No SPIE account? Create an account
or Institutional Sign In via Shibboleth

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $14.40

Non-members: $18.00 ADD TO CART

Show All Keywords

Keywords/Phrases

Search In:

Publication Years