SIMULATIONS OF BCL3 CL-2 PLASMA IN AN INDUCTIVELY-COUPLED GASEOUS REFERENCE CELL/

A gas mixture of BCl3/Cl-2 is widely used in the microelectronics indu stry to etch the Al metal layers on semiconductor wafers. An understan ding of the plasma chemistry is necessary and crucial to improve the u niformity and etch rate of the metal etch on the wafers. To study the plasma characteristics of metal etch reactors a two-dimensional numeri cal plasma reactor model is used to simulate the processing etching ch emistry. The predictive capability of the model depends sensitively on the accuracy of the plasma chemistry mechanisms, the database, and th e surface chemistry that are included in the model. First, the model i s validated over a wide range of power, pressure, and gas compositions with the available experimental data. For low-pressure (few to tens o f mTorr) etching reactors used in the semiconductor industry, the boun dary conditions for the model are very important because of the relati vely large gas mean-free paths. The gas phase chemistry is strongly in fluenced by the surface chemical processes. Unfortunately, the correct boundary conditions for the surface chemistry in the model are extrem ely difficult to set since the chamber wall condition is determined by the wall temperature, surface type (wall material and the covered che mical species), and the process history (wall coverage) of the reactor . The sensitivity of the surface condition is demonstrated with the al uminum etching chemistry in an inductively coupled plasma gaseous refe rence cell reactor geometry by performing numerical simulations with d ifferent wall, recombination coefficients. (C) 1998 American Vacuum So ciety.