Abstract: A method for ashing a resist on a wafer in a plasma reaction chamber comprises the steps of flowing a non-activated oxygen containing gas into the plasma reaction chamber immediately before loading the wafer to the plasma reaction chamber, and then carrying out a plasma ashing of the resist. In one of the preferred embodiments, after the reaction chamber was exposed to the atmosphere and then evacuated to vacuum, a mixed gas of oxygen (90% in volume) and water vapor (10% in volume) was flown into the reaction chamber with 1000 seem and 1 Torr for 5 min. and subsequently the ashing was carried out. The method prevents the ashing rate from decreasing with ashing time.

Abstract: A process for forming a resist mask pattern includes the steps of forming a resist layer of organic material in a multilevel resist process on a layer to be etched, and selectively etching a planarizing lower layer used in the resist layer by using an etching gas of oxygen under a plasma condition, in which a compound gas of at least one element selected from the group consisting of B, Si, Ti, Al, Mo, W and S is added to the etching gas. For example, the compound gas comprises BCl.sub.3, BH.sub.3, TiCl.sub.4, S.sub.2 Cl.sub.2, SiCl.sub.4 or the like. During the etching, a compound oxide, e.g., B.sub.2 O.sub.3, SiO.sub.2 or the like, is deposited on sidewalls of the lower layer to form a protective layer which prevents undercutting.

Abstract: A trench etching process comprises the steps of: preparing a substrate, forming a mask pattern for the trench etching having a material different from that of the substrate, on the substrate, and detecting changes in results of emission spectroanalyses generated by etching the mask pattern and the substrate while using the etching ratios of the mask pattern and the silicon substrate to determine that the trench etching is completed.

Abstract: A downstream microwave plasma processing apparatus useful in fabricating an integrated circuit semiconductor device includes a waveguide, a microwave transmitting window perpendicular to a microwave electric field in the waveguide, a plasma generating chamber below the window and a reaction chamber separated from the plasma generating region by a gas-porous microwave shield. The microwave energy is transmitted into the plasma generating chamber through the microwave transmitting window, and generates a plasma which is confined therein by the shield. Radicals of a short-lived reactive gas, generated in the plasma, pass through the shield and impinge onto a workpiece placed in the reaction chamber. Uniform and effective downstream plasma etching or ashing is produced.