Katsutoshi Mine

Oxidative Curing of Hydrogen Silsesquioxane Resin Films by Electron Beam Irradiation without Additional Heatings and Characterization of the Cured Films

We have developed a new curing process for hydrogen silsesquioxane (HSQ) films, which is applicable for interlayer dielectrics of LSI devices. In this process, an electron beam was used as a curing source. As a result, a practical curing speed was obtained without additional heat treatments at ambient pressure, since electron beams accelerate the oxidative curing reaction on HSQ. The cured films exhibited properties for practical use such as thermal stability, which are equivalent to films cured conventionally by heat treatment. The cracking resistance of the electron-beam-cured films is excellent. A film of 3.0 µm thickness did not show any cracks, whereas a thermally cured film with a thickness of 1.25 µm showed cracks. Furthermore, electron-beam-cured films with a thickness of 2.5 µm did not show any cracks even after nitrogen annealing at 400°C for 1 h. The mechanism of oxidative curing of HSQ by electron beam irradiation was also studied.

Silicone die bond adhesive and clean in-line cure for copper lead frame

Stress analysis by the finite-element method and a die bonding experiment were performed indicating that a die bond adhesive having a very low Youngs modulus is effective in reducing thermal stress. A silicone elastomer adhesive and an in-line cure process named the clean cure process were developed. In this process, the adhesive is cured quickly on a heat column, thus volatile organic species which affect the yield and reliability of devices are reduced significantly during cure. The bonding of large silicon dice to copper lead frames was successfully performed using this technology. >

Highly sensitive microresinoid siloxane resist for EB and deep-UV lithography

The multi-layer resist process is an essential technology for the future of both electronbeam (EB) and deep UV exposure. This process has been expected to reduce the proximity effect in EB exposure, and to planarize the high steps of device surfaces. A new bi-layer siloxane resist has been developed that gives negative tone images and has high sensitivity and high resolution for EB and deep UV lithography. High sensitivity was accomplished by introducing a chloromethyl-phenyl-alkyl (CPA) group, which has a resonant effect, as a functional group into the siloxane resin. For deep UV, the advantage of the siloxane resist is that is has a transmittance over 90%. The resist patterns of 0.2 micrometers at 10 (mu) C/cm2 and 0.3 micrometers at 80 mJ/cm2 were obtained for a shaped electron beam and deep UV, respectively. The O2 reactive ion etching (RIE) selectivity of the siloxane resist over the underlaid organic layer was about 30. The new siloxane resist is suitable for 64 M and 256 M DRAM lithography processes.