Abstract
Thin Layer Imaging (TLI) technique offers opportunity for lithographic performance gain as well as issues relating to its complexity of the process. Of those improvement possibilities, utilizing hyper fine resolution one can gain using very thin (<250 nm) imaging layer, has been a gateway to access the otherwise unavailable sub-wavelength features using the currently available exposure tools. However, pattern transfer from the imaging layer (wet developed) to the main etch resistance layer (organic bottom layer also act as BARC, Bottom Anti Refractive Coat, during exposure) requires considerable efforts in bottom layer dry-develop etch process optimization on a plasma etch chamber. And, such an extra process requires significant amount of engineering attention to the multi layer process scheme. In this paper, we report the 140 nm (k1 equals 0.44, including true dense, 1:1 arrays) contact hole printing results (lithographic performance including resolution, focus/exposure latitudes, proximity effects) using standard binary chrome-on-quartz mask as well as the subsequent pattern transfer process optimization. The lithographic exposure was performed on a 10X ISI microstepper operating at 193 nm ArF laser source located at the RTC (Resist Test Center) of the International Sematech. The dry development DOE experiments were performed on a LAM TCP9400PTX inductively coupled plasma (ICP) etch chamber also residing at the RTC. The effect of process conditions (TCP power, bias power, O2/SO2 gas flow/ratio, and chamber pressure and chuck temperature) on the integrity of pattern transfer (etch rate, selectivity, CD bias, side wall profile) were investigated by full factor designed experiments.
