Ultra Low-K Inorganic Silsesquioxane Films with Tunable Electrical and Mechanical Properties

Abstract

Low-k dielectric films have been developed using a new silsesquioxane based chemistry that allows both the electrical and mechanical properties to be tuned to specific values. By controlling the composition and film processing conditions of spin-on formulations, dielectric constants in the range 1.5 to 3.0 are obtained with modulus values that range from 1 to 30 GPa. The modulus and dielectric constant are tuned by controlling porosity, which varies from 0 to >60%, and final film composition which varies from HSiO3/2 to SiO4/2. The spin-on formulation includes hydrogen silsesquioxane resin and solvents. Adjusting the ratio of solvents to resin in the spin-on formulation controls porosity. As-spun films are treated with ammonia and moisture to oxidize the resin and form a mechanically self-supporting gel. Solvent removal and further conversion to a more “silica-like” composition occur during thermal curing at temperatures of 400 to 450°C. The final film composition was controlled through both room temperature oxidation and thermal processing. Final film properties are optimized for a balance of electrical, mechanical and thermal properties to meet the specific requirements of a wide range of applications. Processed films exhibit no stress corrosion cracking or delamination upon indentation, with indenter penetration exceeding the film thickness, and followed by exposure to water at room temperature. Films also exhibit high adhesive strength (> 60MPa) and low moisture absorption. Processing conditions, composition and properties of thin are discussed.

Structural, electrical and mechanical properties of templated silsesquioxane porous films

“…A similar behavior was observed for the hardness, where the values were reduced from 1.21 GPa for HMSQ film to 0.71 and 0.39 GPa for 10:90 and 20:80 PAMAM:HMSQ films, respectively. The results that increased porosity compromised the mechanical properties of the films agree well with the literature [20][21][22]. Nevertheless, higher elastic modulus and hardness were found for present samples compared to the literature values.…”

Structural Comparison of Hydrogen Silsesquioxane Based Porous Low-k Thin Films Prepared with Varying Process Conditions

“…The average mass densities of the films with dielectric constants of 2.2, 2.0, and 1.5 are approximately 1.05, 0.85, and 0.64 g/cm 3 , respectively. These values are all significantly lower than the density of standard HSQ films (1.4−1.5 g/cm 3 ) . As a self-consistent check, the SXR average mass densities are found to be in good agreement, within experimental error, with the values determined from the RBS measurements.…”

“…The as-spun films undergo gelation through exposure to wet ammonia for 30−120 s at room temperature. After the wet ammonia treatment, the films are baked on a hot plate at 150 °C for 60 s under ambient atmosphere and cured in a furnace at 450 °C for 1 h in a low oxygen atmosphere (<10 ppm). , Increasing mass fractions of tetradecane solvent are used to lower the dielectric constant. Longer wet ammonia treatment times are applied to increase the degree of cure or the number fraction of Si−H of the films.…”

The Effects of Dilution Gas and Pressure on the Properties of PE-CVD Low-k Film

“…To date, many studies have concentrated on the development of low-k film and Cu interconnect process integration. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] From a manufacturing point of view, low-k interlayer dielectric films are classified into two groups: spin-on dielectric ͑SOD͒ [1][2][3][4] and plasma-enhanced chemical vapor deposition ͑PE-CVD͒ films. [5][6][7][8][9][10][11][12][13] The k value of the SOD film has been reduced to 2.0 or below 2,4 and is lower than that of PE-CVD low-k film.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] From a manufacturing point of view, low-k interlayer dielectric films are classified into two groups: spin-on dielectric ͑SOD͒ [1][2][3][4] and plasma-enhanced chemical vapor deposition ͑PE-CVD͒ films. [5][6][7][8][9][10][11][12][13] The k value of the SOD film has been reduced to 2.0 or below 2,4 and is lower than that of PE-CVD low-k film. It is well known, however, that the mechanical strength is less than that of conventional dielectric films.…”