Sub-Lithography Imaging Method
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
A process sequence is shown which produces line structures which are much smaller than possible using conventional lithography. The following process sequence is capable of defining lines with precise dimensions which are less than 500 angstroms wide, and in the width of one lithographic dimension (0.5 microns, for example), it is possible to produce two lines and one space. Fig. 1 shows an imaged layer of nitride over a layer of oxide on a substrate. Using the nitride as a mask, some of the oxide is isotropically etched, undercutting the nitride, as shown in Fig. 2. Next a conformal film of the desired type, i.e., chemical vapor deposition (CVD) of polysilicon, tungsten etc., is deposited over the structure, as shown in Fig. 3.