Effect of H atoms and UV wideband radiation on cured low-k OSG films

Abstract Effects of hydrogen atoms and UV radiation ( λ > 210 nm) on nanoporous organosilicate glass (OSG) low- k films are studied in the temperature range from 20 °C to 300 °C. The purpose of the study is to understand the mechanisms of low- k films modification that can happen during the cleaning from carbon containing residues formed from sacrificial porogen and accumulated during the air storage. It is shown that exposure of low- k films to hydrogen atoms at low temperature leads to slight modification of hydrocarbon bonds in hydrocarbon residues not bonded to Si. At high temperature ( T ⩾ 300 °C), the relative concentration of –CH x bonds changes in a complex way and depends on the amount and structure of the carbon-containing compounds. The general trend is relatively rapid decrease of –CH 2 bonds concentration, while the terminal –CH 3 groups are more stable. Temperature also initiates the reaction of hydrogen atoms with low- k with partial modification of low- k matrix breaking Si–O bonds. The destruction of Si–O and Si–CH 2 groups leads to the formation of oxygen-deficient centers, followed by the formation of Si–(CH 3 ) 2 groups due to their interaction with methyl groups. At 300 °C, the total number of Si–CH 3 + Si–(CH 3 ) 2 groups starts to decrease indicating on partial removal of the methyl groups bonded to silicon. Besides with increasing temperature a slight modification of the structure of matrix under exposure to H atoms is also observed. UV radiation has almost no effect on these processes in the studied conditions. Thus, there exist the ‘optimal’ conditions for H atom impact on OSG low- k films which allows improving film performance by removing porogen residue without damage.