Control of the contact hole diameter using inductively coupled fluorocarobon and hydrocarbon plasmas

Summary form only given. A reduction in the feature size of integrated circuits (ICs) is critical to achieve dynamic random access memory (DRAM) devices with high density. Optical lithography is widely used to transfer patterns from the mask to the substrate. Due to physical limitations of optical lithography, efforts have been made to extend lithography limits such as double patterning technology. In this work, a novel method to reduce the feature size of a contact hole without lithographical technique is presented. The sample was a 2-μm thick Si02 film deposited on a silicon wafer. A 1-μm photoresist (PR) layer having a hole pattern of around 0.3 μm was used as a mask. The feature size of the pattern (hole) of the PR mask was firstly controlled by depositing protective layers on the sidewalls of the pattern. The protective layers were formed using inductively coupled fluorocarbon or hydrocarbon plasmas. By varying the process parameters such as induction power, pressure, and flow rate, the size and anisotropy of the mask pattern were controlled. After reducing the feature size of the mask pattern, the oxide substrate was etched in C4F6/Ar/θ2/CH2F2 plasmas. The diameter of the oxide contact hole was controlled depending on the reduction in the mask pattern. It was successfully reduced to more than 50 % of the original size of the mask pattern. The effect of the shape of the mask pattern on the contact hole etching was also investigated.