Application of CF_4 Plasma Activation in Low Temperature Silicon Direct Bonding

Before bonding,the silicon wafers are pretreated with CF4 plasma and underwent hydrophilic treatment with RCA and DI water.Then complete bonding can be achieved by 40 h of annealing treatment at 300℃ in N2 ambient.The bonding strength is as strong as that of bulk silicon.The experiments show that CF4 treatment to silicon wafers can not only activate them but also polish their surfaces effectively,and it can improve the pre-bonding greatly.