Anisotropic pattern transfer of fine resist features to silicon nitride via an intermediate titanium layer

• Published in: Microelectronic engineering Vol. 35; no. 1-4; pp. 99 - 102
• Main Authors: Midha, A., Murad, S.K., Weaver, J.M.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.1997
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/S0167-9317(96)00164-5

We demonstrate a new technique for transferring high resolution features written in PMMA into silicon nitride with high aspect ratio. By dry etching an intermediate titanium layer with SiCl4 using ECR-RIE, a resist erosion rate of better than 2:1 can be achieved from PMMA. This pattern is subsequently transferred into silicon nitride using high power and bias C2F6 reactive ion etching. Features down to 30nm have been etched vertically to a depth of 150nm without any observable overcut or undercut, and with little erosion of the titanium masking layer. The technique may have applications to the manufacture of x-ray masks and zone plates, fabrication of optical elements, and wherever multilayer resist schemes involving titanium or oxygen etching are used.