Study of atomic transport mechanisms during thermal nitridation of silicon in ammonia using 15N and D labelled gas
Study of atomic transport mechanisms during thermal nitridation of silicon in ammonia using 15N and D labelled gas
复制标题
使用 15N 和 D 标记气体研究硅在氨中热氮化过程中的原子输运机制
DOI：
10.1016/0169-4332(86)90073-5
复制
发表时间：
1986
影响因子：
6.7
通讯作者：
S. Rigo
中科院分区：
文献类型：
--
作者：
C. Maillot;H. Roulet;G. Dufour;F. Rochet;S. Rigo
以15N为示踪剂，研究了95 0℃和2×10−5Torr下氨气中硅热氮化机理。首先在14NH3中生长氮化物层，然后在15NH3中进一步生长，通过核显微分析和氮化物层的逐步化学溶解相结合的方法获得了15N的轮廓。由此可以看出，氮化膜由位于Si/氮化物界面附近的14N层和位于薄膜外表面附近的15N层组成。结果还表明，氮化物网络中的氮与氨气中的氮之间不存在同位素交换。这些结果表明，这种生长不是通过NH3分子的氮化物膜的间隙传输发生的，也不是通过氨气分解产生的任何其他氮化物种发生的。还利用ND3氮化反应研究了氢化物种的可能掺入。由于在这种薄膜中的相对浓度小于10−4，氨很可能在外表面解离，氢化物种与网络没有明显的反应。从这些实验可以得出结论，氮化硅层的生长是通过硅原子通过然后与氮化物气体反应的层的传输；或者是氮网络缺陷(空位或间隙)在一个方向上的逐步迁移。在这种情况下，缺陷应该带电，并且希望的方向应该由来自硅衬底的电子对吸附在氮化物外部表面的氮化物种充电而产生的强大电场产生，因为氮化物膜的厚度非常小(<；40？)(隧道效应或热离子效应)。
Thermal silicon nitridation mechanisms in ammonia gas at 950°C and under 2 × 10−5Torr were investigated by using15N as a tracer. Nitride layers first grown in14NH3were further grown in15NH3.15N profiling was obtained by combining nuclear microanalysis with step-by-step chemical dissolution of the nitride layer. Thus one can show that the nitride film consists of a14N layer located near the Si/nitride interface and a15N layer located near the external surface of the film. It was also shown that there is no isotope exchange between the nitrogen of the nitride network and of the NH3gas. These results indicate that the growth does not occur by interstitial transport through the nitride film of the NH3molecules nor by any other nitrogenated species resulting from a decomposition of the ammonia gas. A possible incorporation of hydrogenated species was also examined using ND3nitridation. As the relative concentration of deuterium in such a film was less than 10−4, ammonia most probably dissociates at the outer surface and hydrogenated species do not react appreciably with the network.From these experiments, it can be concluded that the growth of the silicon nitride layer occurs by either:-transport of silicon atoms through the layer which then react with the nitridant gas;-or a step-by-step migration of a nitrogen network defect (vacancy or interstitialcy) in only one direction. In such a case, the defect should be electrically charged and the hoping direction should be imposed by a strong electrical field arising from the charging of nitrogenated species adsorbed at the external nitride surface by electrons coming from the silicon substrate because of the very small thickness of the nitride film (< 40 Å) (tunnel or thermionic effects).