Organic developer-soluble bottom anti-reflective coatings (DBARCs) are commonly used in the photolithographic process for implant and high-k/metal gate integration. They provide added reflectivity control over topography compared top anti-reflective coatings (TARCs). DBARCs are coated onto substrates and then removed during the develop step with the resist. Occasionally a thin post-develop residue (PDR) remains after the DBARC removal process. The main drivers of this residue are DBARC bake temperature, followed by develop time. For this investigation the amount of residue was tested using Si, SiO 2 , native SiO 2 , SiN, and HfO 2 substrates at different bake temperatures. In addition, contact and proximity baking are compared and shown to be equivalent in terms of their effect on PDR. This work demonstrates that optimizing the bake process of a DBARC is an effective way to control PDR on a variety of substrates.

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This paper describes the chemistry and performance of a new family of wet-developable (wet) bottom anti-reflective coatings (BARCs) that have been developed for 193-nm implant layer applications. These BARCs, which are light sensitive and positive working, are imaged and developed in the same steps as the covering 193-nm photoresist. The BARCs are spin coated from organic solvents and then insolubilized during a hot plate bake step. The resulting cured films exhibit minimal solubility in numerous organic solvents. Resolution of a photoresist A and light-sensitive BARC I at optimum exposure (Eop) on a silicon substrate was 150-nm L/S (1:1), with good sidewall angle and no scumming. These best-case results utilize a first reflectivity minimum BARC thickness and meet the desired resolution goals for noncritical implant layers. BARC optical parameters can easily be adjusted by altering the polymeric binder. PROLITH™ modeling shows that near zero reflectance can be achieved on a silicon substrate for both a first and a second reflectivity minimum BARC thickness. The light-sensitive, wet BARCs are both spin-bowl and solution compatible with most industry standard solvents. A selected BARC from this family of wet products was shown to be stable, providing reproducible film properties over several months of ambient storage conditions.

Developer-soluble bottom anti-reflective coatings (DBARCs) were originally designed for use in implant lithography processes. Throughout the development cycle, two main DBARC platforms emerged, nonphotosensitive DBARC (non-PS DBARC) and photosensitive DBARC (PS DBARC). While both platforms have been able to achieve acceptable performance for implant processes, each has advantages and disadvantages. The characteristics of each system are used to recommend a platform for use in various implant processes. DBARC processes are now being compared to single-layer resist and dry BARC processes due to additional applications such as wet-etch layers for high-k dielectric metal gate (HKMG). Integrating a new technology into production is complicated. Therefore, for each of these new applications, the different DBARC platforms have been reviewed to compare performance. The analysis allows us to recommend a DBARC and a favorable process for each application, thereby decreasing development time and cost.

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