John F. Rembetski

Plasma-based dry etching techniques in the silicon integrated circuit technology

Plasma-based dry etching techniques play a major role in the formation of silicon-based integrated circuits. The first part of this paper reviews our understanding of the means for achieving etching directionality and selectivity in reactive etching using glow discharges. Relevant trends in magnetically enhanced rf diode systems, microwave-excited electron cyclotron resonance plasmas, process clustering, real-time process monitoring and control, and computer modeling of glow discharges are discussed in the second part of the paper.

193-Nm Excimer Laser-Assisted Etching of Polysilicon Films Using Cl 2

193-nm excimer laser-assisted etching of polysilicon was studied in the presence of CI2. Maximum etch rates of 1.25 A/pulse were obtained for pressures of about 400 torr and fluences exceeding 400 mJ/(cm 2 -pulse). The etch rate increased with both fluence (100-550 mJ/(cm 2 -pulse)) and pressure (50-800 torr). An adsorptive etch mechanism similar to NF 3 etching has been proposed, where Cl 2 molecules diffuse to the surface, adsorb, and then react after absorbing laser radiation. This is consistent with photon and molecular flux considerations and the availability of reaction sites. Thermal effects where Cl 2 molecules decompose to Cl atoms on “hot” polysilicon surfaces may assist this process, and appear to dominate under conditions of lower pressure ( 2 absorption cross section at 193 nm. Simple projection etching results showed that micron lines can be etched in polysilicon by use of this chemistry.