CHEMICAL-VAPOR-DEPOSITION IN HIGH-DENSITY LOW-PRESSURE PLASMAS - REACTOR SCALE-UP AND PERFORMANCE

In most applications, plasma enhanced chemical vapor deposition (CVD) of high-quality materials requires control of process parameters over a wide range. In particular, high-density low-pressure plasmas capable of producing significant ion fluxes compared to neutral fluxes, and independent substrate biasing which allows accurate adjustment of the ion bombardment energy may lead to high-performance deposited layers. Results in low-temperature Si epitaxy, SiO2, CU and W deposition are presented which illustrate the capabilities of such plasmas. However, deposition rate and film uniformity remain the key requirements in many industrial fields, including the microelectronics industry with the processing of flat panels and increase in wafer diameters. In fact, the limiting factor of many industrial applications lies in the difficulty of producing large (up to square meters) uniform, dense plasmas. In the conventional cylindrical configuration of plasma reactors, the ability to process large-dimension substrates is dependent on the generation of large volumes of plasma. Unfortunately, due to ion volume recombination, the production of large volumes of uniform dense plasma must be ruled out. Clearly, treatment of a planar substrate with a uniform plasma source is more suitable. The uniform distributed electron cyclotron resonance (UDECR), in which linear microwave applicators can sustain constant amplitude standing waves along a multipolar magnetic structure, can be used to make large planar plasma sources. The performance of such a plasma is presented in terms of uniformity and density, allowing the process optimized in laboratory reactors to be scaled-up to much larger reactors without any alteration in the characteristics.