The manufacture of multilayer structures typically involves patterned etching of areas of the semiconductor surface that are covered by a photoresist protective material. One etching technique is reactive ion etching (RIE). This process involves positioning a semiconductor wafer in a reaction chamber and feeding etchant gases into the chamber. The etchant gases are dissociated in a radio frequency (RF) field so that ions contained in the etchant gases are accelerated to the wafer surface. The accelerated ions combine chemically with unmasked material on the wafer surface. As a result, volatile etch product is produced and is incorporated into the plasma. The concentration of the volatile etch product can be tracked in order to determine the end-point of the RIE process, i.e., when the chemical reaction has removed the desired level of material from the wafer surface. During the RIE process, a single layer or multiple layers of material or film may be removed. These materials may include, for example, silicon nitride (Si3N4), PSG, silicon dioxide (SiO2) and poly-silicon (PSi).
U.S. Pat. No. 3,398,033, issued to Haga, discusses wet etching of silicon carbide by the use of a chemical reaction of a mixture of oxygen (O2) and chlorine (Cl2) heated to between 1200° C. and 1300° C. U.S. Pat. No. 4,351,894, issued to Yonezawa, discloses a plasma etch process for removing SiC using carbon tetrafluoride (CF4) and optionally oxygen (O2). U.S. Pat. No. 4,595,453, issued to Yamazaki, discloses using hydrogen fluoride gas (HF) in a dry etch plasma process.
U.S. Pat. Nos. 4,865,685 and 4,981,551, both issued to Palmour, disclose reactive ion etching of SiC using NF3 and, alternatively, NF3 mixed with O2 and argon (Ar).
There is a need in the art for improved techniques for plasma etching of silicon carbide with selectivity to overlying photoresist or hard mask and/or dielectric layers overlying or underlying a silicon carbide layer.