AVS 46th International Symposium
    Manufacturing Science and Technology Group Thursday Sessions
       Session MS+PS-ThM

Paper MS+PS-ThM11
Environmentally Harmonized Silicon Oxide Selective Etching Process Employing Novel Radical Injection Technique

Thursday, October 28, 1999, 11:40 am, Room 611

Session: Environmentally Benign Manufacturing
Presenter: K. Fujita, Nagoya University, Japan
Authors: K. Fujita, Nagoya University, Japan
S. Kobayashi, Nagoya University, Japan
M. Hori, Nagoya University, Japan
T. Goto, Nagoya University, Japan
M. Ito, Wakayama University, Japan
Correspondent: Click to Email
Dry etching of silicon oxide (SiO@sub 2@) films is an essential process for fabricating deep contact holes in ultra large-scale integrated circuits (ULSIs). This process has been developed by using high-density plasmas employing stable fluorocarbon feed gases such as CF@sub 4@, C@sub 4@F@sub 8@ and so on. Fluorocarbon gases, however, cause a serious environmental problem, namely global warming and hereby the production of fluorocarbon gases would be restricted. Recently, we proposed a novel radical injection technique using a fluorocarbon radical source replacing stable fluorocarbon feed gases for preventing global warming, where polytetrafluoroethylene (PTFE) is ablated by a CO@sub 2@ laser and the generated fluorocarbon species (C@sub x@F@sub y@) such as reactive radicals are injected into the plasma reactor from externally. This technique, therefore, enables us to achieve a new plasma chemistry and a high-efficiency abatement due to the high exhaustion efficiency of reactive radicals coming from the plasma reactor compared with the stable gases. In this study, this system has been successfully applied to high-density plasma etching of SiO@sub 2@ over Si process and CF@sub x@ (x=1-3) radical densities in the plasma were evaluated by infrared diode laser absorption spectroscopy (IRLAS). A permanent magnet ECR plasma source which is very compact in size and easily scaled up to the large wafer size (~30 mm@phi@) was employed. The ECR zone was set about 6.5 cm above substrates. The Etching rate of SiO@sub 2@ and selectivity (SiO@sub 2@/Si) were 650 nm/min and 8, respectively at a microwave power of 400 W, a pressure of 6.5 Pa, a flow rate of 80 sccm and a bias voltage of -450 V in the ECR plasma employing the novel radical injection technique. These results indicate good characteristics compared with the conventional electromagnet ECR plasma. The etching mechanism are discussed on the basis of the behaviors of CF@sub x@ (x=1-3) radicals measured by the IRLAS.