单晶SiC化学机械抛光液的固相催化剂研究

Solid Catalysts Based on Fenton Reaction for Si C Wafer in Chemical Mechanical Polishing

针对单晶Si C化学机械抛光使用的抛光液,研究了产生芬顿反应Fe、Fe O、Fe_2O_3、Fe_3O_4等4种铁系固相催化剂的效果。结果发现当Fe_3O_4作为催化剂时,Si C表面能够产生明显的化学反应,生成较软易去除的Si O_2氧化层,化学机械抛光时材料去除率最高达到17.2 mg/h、表面粗糙度最低达到R_a2.5 nm。相比Fe、Fe O、Fe_2O_3等固相催化剂,Fe_3O_4更适宜用作Si C的化学机械抛光。抛光液中Fe^(2+)离子浓度和稳定性是决定芬顿反应速率和稳定性的重要因素,固相催化剂电离自由Fe^(2+)能力的差异直接影响了化学抛光液中的Fe^(2+)浓度,固相催化剂电离Fe^(2+)的能力越强,抛光液中Fe^(2+)浓度就越高,芬顿反应速率越快,与Si C进行化学反应速度越快,材料去除率越高,抛光质量越好。

Aiming at the CMP solution of single crystal Si C, the catalytic efficiency of Fe-based solid catalysts such as Fe, Fe O, Fe2O3 and Fe3O4 are studied. When Fe3O4 is used as the catalyst of Fenton reaction, an obviously chemical reaction happens on the surface of Si C and a relatively soft Si O2 layer which is easier to be removed is generated, and the highest material removal rate which is 17.2 mg/h and the minimum surface roughness which is Ra2.5 nm are obtained after chemical mechanical polishing. Fe3O4 is more appropriate for CMP of Si C compared with other solid catalysts such as Fe, Fe O and Fe2O3. The concentration and stability of Fe^2＋ in chemical polishing solution are crucial factors deciding the rate and stability of Fenton reaction, and the concentration of Fe^2＋ is directly affected by the ability of ionizing free Fe^2＋ of solid catalyst. The stronger the ability of ionizing free Fe^2＋ of solid catalyst is, the higher the concentration of Fe^2＋ in polishing solution will be, and then the faster the rate of Fenton reaction will be. In this case, a higher material removal rate and a better polishing quality of Si C will be obtained in CMP.