Ga在SiO2／Si系下的扩散模型与分布规律

Diffusion Model and Distribution Rule of Ga in SiO2/Si System

摘要:

为给出受主杂质Ga通过SiO2／Si系统实现开管掺杂过程的模型描述和Si体内遵循的主要分布规律，利用二次离子质谱分析(SIMS)、薄层电阻(R□)测量方法，对Ga在SiO2／Si系下的扩散特性、硅表面及体内分布进行了系统研究，得出新的结论：(1)Ga在SiO2中的固溶度较低而扩散系数很大，故形成线性分布形式，Ga在Si中的溶解度相比SiO2很大，SiO2-Si界面的分凝使其以较高平衡浓度分配入硅中，两者的连续确立了开管扩Ga模型。(2)在严格控制硅片温度TSi、杂质源分解温度TGa2O3、反应气体流量CH3，调整预沉积、再分布及其两者的重复组合，便可在硅内得到任意理想的杂质分布；(3)Ga原子是通过理想表面(SiO2-Si界面)扩散入体内，避免与外界的接触沾污，获得了高均匀性、高重复性的扩散表面及非常平行的平面结。

Abstract:

Secondary ion mass spectra analysis (SIMS) has been employed to construct the diffusion model of Ga in SiO2/Si system during doping and to study the distribution of Ga in silicon. Based on the above model, conclusions have been drawn as following: (1) Ga has a linear distribution and enters Si due to the segregation of SiO2/Si interface. As a result, the diffusion model of Ga was established. (2) Through controlling the temperature and adjusting the time during pre-deposition, and combination of them, an idea purity distribution can be obtained. (3) The planar junction with high uniformity and good repetition will be obtained by the above process, indicating that Ga has ideally diffused into silicon through the perfect interface.