We investigated dry development of resist in the Lam Research TCP 9400SE plasma etcher to meet process specifications for tea 180 nm lithography generation. A full-wafer imaging interferometer was integrated onto the tool, and used to measure etch rates, uniformities and stability of same in-situ. Etch rates of greater than 5000 A/min and selectivities of greater than 15:1 of silylated to unsilylated resist can be obtained in oxygen plasmas in the TCP in the electrode temperature range studied. However, lateral etching (undercut) underneath patterned oxide islands was measured to be approximately 30 nm/min for a typical oxygen process and could not be eliminated in pure oxygen plasmas. To control the lateral etching, we investigated the use of SO2 addition to the oxygen discharge. SO2 addition was found to eliminate the lateral etching component of the resist etch and reduce the etch lag effect, while having a minimal reduction in the overall resist etch rate. We have used the SO2 process to minimize the effect of over-etch on developed resist profiles.
A transformer coupled plasma (TCP) source has been developed for use in the etching of polysilicon films. The TCP is a planar, inductive source which can achieve high density operation (> 1012 cm-3) over a large pressure range (1 - 100 mT). The etching characteristics of this source are described and process trends for etch rate, selectivity, and profile microloading are presented. Process requirements for polysilicon films with sub- half micron features are achieved using the TCP source by separately controlling the plasma parameters and the wafer bias.
Dry developable resist systems based on silylation have been presented as an alternative solution for submicron and deep submicron lithography. The DESIRE process (Diffusion Enhanced Silylated Resist) is the most well-known example of such a process. In this paper the dry development step using reactive ion etching has been investigated using a TEGAL MCR (Magnetically Confined Reactor). The TEGAL MCR system is a versatile tool which provide two major improvements over the classical RIE: the magnetical confinement of the plasma and the triode RF coupling system. In this paper the influence of the pressure the bias power and the oxygne flow rate on the etch rate and the shape of the photoresist pattern was inverstigated. The etch rate of resist and associated uniformity depend on the plasma etching parameters. The exposure dose is however the major parameter determining the critical dimension (CD). I .