The mechanism of etch stop in contact hole etching has been studied. It was found that in high aspect ratio holes, even though the incident ions lose charge due to collision with the sidewall, they are able to bombard the bottom of the hole maintaining their high energy. It was also confirmed that the redeposition of sputtered species from the fluorocarbon polymer on the hole sidewall induces the etch stop at the bottom of the high-aspect hole. Furthermore, it was observed that etch stop occurs at higher aspect ratios for the same hole diameter in oxide films with higher boron and phosphorous dopant concentrations. This is explained by the effective removal of etch-inhibiting carbon species due to the release of more oxygen at a higher etch rate in highly doped oxide film. In conclusion, the etch stop in a high-aspect-ratio hole is determined by the balance between the effects of high-energy-species bombardment and etch inhibition of carbon species.

We have developed a novel electron-beam (e-beam)/deep-ultraviolet (DUV) intralevel mix-and-match (ILM&M) lithography as a production-viable technology. The main feature of the ILM&M lithography is its use of a DUV biased exposure method for increased throughput and a combination of a variably shaped e-beam/character projection writer with a step-and-repeat DUV scanning system for accurate intralevel butting between e-beam and DUV patterns. It was demonstrated that the throughput of e-beam writing in the ILM&M lithography could reach about three times that of e-beam lithography, and that an intralevel butting accuracy of less than 50 nm could be achieved. The proposed ILM&M has been successfully applied to the development and early production of leading edge devices at our laboratory.

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In-field heat treatments of an MnGa diffusion couple were performed at 773 K for 12, 24 and 48 h to investigate the phase formation under magnetic fields. Formation of the MnGa 3 , Mn 2 Ga 5 , MnGa, Mn 3 Ga 2 and ¢-Mn phases was confirmed for magnetic fields of 0 T and 5 T. For a diffusion-controlled process, there is a parabolic relationship between the thickness of the phase layers and annealing time for the MnGa and Mn 2 Ga 5 phases. The parabolic coefficients of MnGa and Mn 2 Ga 5 for a zero magnetic field were determined as 8.7 © 10 ¹3 µm 2 s ¹1 and 4.6 © 10 ¹1 µm 2 s ¹1 respectively. For a magnetic field of 5 T, the parabolic coefficients were evaluated as 11 © 10 ¹3 µm 2 s ¹1 for the MnGa phase and 4.5 © 10 ¹1 µm 2 s ¹1 for the Mn 2 Ga 5 phase.