Control of electric charge at the interface in the RTO and low temperature oxidation of SOI

在硅的快速热氧化和低温热氧化中，本征应力的不完全松弛导致大量间隙原子的发射。因此，氧化膜的某些性质和界面态是随时间变化的，这使得用通常的线性-抛物线模型来解释氧化行为变得困难。此外，在SOI的情况下，由于掩埋氧化物的存在而产生的复杂的应力状态使得很难获得质量良好的氧化层。在这样的背景下，我们建立了适合于动态分析热氧化过程的实验装置，建立了研究氧化机理和控制氧化层性能的实验方法学。因此，我们在硅的低温热氧化研究中获得了许多有趣的基础数据和新的知识和信息如下：1.从原位椭偏仪测得的氧化曲线中分析了氧化参数。提出了间隙硅原子发射的应力相关模型，并进行了实验验证。4.不同温度和不同氧化物种下氧化速率的取向关系揭示了本征应力在氧化过程中的作用。5.在氧化气体中加入适量的NF3，降低了氧化膜中的残余应力，改善了C-V特性。6.利用X射线衍射仪，我们发现了不同氧化温度下的氧化物结构，种类和晶片取向。

In the rapid thermal oxidation (RTO) and in the low temperature thermal oxidation of silicon, the incomplete relaxation of intrinsic stress leads to the emission of a lot of interstitial atoms. Consequently, some properties of oxide films and the interface states vary from time to time, which causes it difficult to explain the oxidation behavior with the usual linear-parabolic model. Moreover, in case of the SOI,the complex stress states due to the existence of buried oxide makes it difficult to obtain an oxide layr of good quality. From such a background we constructed the experimental apparatus which was suited for the dynamic analyzes of the thermal oxidation process and established an experimental methodology to study the oxidation mechanism and to control the properties of oxide layr. As a consequence, we obtained many interesting basic data and new knowledge and information in the low temperature thermal oxidation of silicon as follows :1.The oxidation parameters were analyzed from the oxidation curves measured ith an in-situ ellipsometer, and the difference in the oxidation mechanism between the high and the low temperature thermal oxidation was experimentally verified.2.It was found that the emission of interstitial silicon atoms ruled the oxidation rate.3.A stress related model for the emission of interstitial atoms was proposed and experimentally confirmed.4.The orientation dependencies of oxidation rates in varied temperature and oxidation species revealed the roles of intrinsic stress in the oxidation process.5.The addition of an appropriate amount of NF3 in the oxidizing gas reduced the residual stress in the oxide films and improved the C-V characteristics.6.By using an X-ray diffraction technique we found different oxide structures depending on the oxidation temperature, species and the wafer orientation.