AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP15
Controlling of UV Radiation Damages using On-wafer Monitoring Technique

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: M. Okigawa, Tohoku University, Japan
Authors: M. Okigawa, Tohoku University, Japan
Y. Ishikawa, Tohoku University, Japan
Y. Katoh, Tohoku University, Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
Gate insulator for metal-insulator silicon (MIS) devices needs high breakdown voltage, low leakage current and low interface states for robust semiconductor devices. Generation of electron-hole pairs in dielectric film as the gate insulator was measured by using our developed on-wafer monitoring technique during the plasma etching processes. To detect the generation of electron-hole pairs by plasma-induced electrical current in the insulator, we developed four types of on-wafer monitoring devices. Each device has an insulator structure such as single SiO@sub 2@ film, single Si@sub 3@N@sub 4@ film, SiO@sub 2@ film stacked on Si@sub 3@N@sub 4@ or Si@sub 3@N@sub 4@ film stacked on SiO@sub 2@. We found that the electron-hole pairs were generated in the insulators by the plasma-induced ultraviolet (UV) photons. We use three gas mixtures (CF@sub 4@+O@sub 2@, C@sub 2@F@sub 4@+O@sub 2@ and C@sub 4@F@sub 8@+O@sub 2@) to vary the wavelength of the emitted UV light in the plasma. The induced current depended on the UV wavelength meaning gas chemistry and the on-wafer monitoring device structures. In the SiO@sub 2@ film, CF@sub 4@ induced the most current of the three gas mixtures because CF@sub 4@ emitted the strongest intensity of the UV light having shorter wavelength than 140 nm as the SiO@sub 2@ band gap of 8.8eV. On the other hand, in the case of the Si@sub 3@N@sub 4@ single film, C@sub 4@F@sub 8@ has larger plasma induced current than other two gas mixtures. C@SUB 4@F@sub 8@ has the most intense UV lights of shorter than 250 nm that is the band gap of Si@sub 3@N@sub 4@, 5.0eV. Additionally, we evaluated the plasma-induced current using multi-layer insulator devices that consisted of both SiO@sub 2@ and Si@sub 3@N@sub 4@. The structure of Si@sub 3@N@sub 4@ on SiO@sub 2@ drastically reduced the plasma-induced current as compare with the structure of SiO@sub 2@ on Si@sub 3@N@sub 4@. This might be caused by the difference of the band-energy structure between them.