(446g) Study of Low-K Film Repair and Pore Sealing Using Chlorosilanes Dissolved in Supercritical Carbon Dioxide

Surface modification of porous methylsilsesquioxane (p-MSQ) films was performed by treatment with binary mixtures of a chlorosilane and supercritical carbon dioxide at a pressure of 9.0 MPa and at three temperatures: 33°C, 38°C, and 43°C. The p-MSQ films were treated to an oxygen plasma before processing, which produced a contact angle below 10° due the presence of silanol (Si-OH) groups. Analysis of the changes in thickness, pore size distribution, hydrophobicity, dielectric constant, and chemical bonding was performed using ellipsometry, ellipsometric porosimetry, goniometry, electrical measurements, and Fourier transformed infrared spectroscopy (FTIR), respectively. Trimethylchlorosilane (TMCS) and methyltrichlorosilane (MTCS) were investigated at various concentrations. These produced different responses in the variables under study at the different conditions of treatment (temperature, time of reaction, and concentration). A batch reactor was used to bring the reagents into contact with the modified film. The pressure and temperature were controlled with an ISCO syringe pump and a temperature controller loop (heating tape, PID controller, and K-thermocouple). The pump was also used to feed the reactor with CO₂ and to force the chlorosilane inside the pressurized reactor. The results show that properties of the recovered films can be tunable with changes in the conditions of reaction. Layers with thickness greater than a monolayer were deposited by both chlorosilanes, and a favorable intermolecular reaction of MTCS was appreciated producing films thick enough to be used for diffusion barrier deposition. The results showed that a minimum thickness is needed to produce these desirable effects.