CHEMICAL ETCHING OF SILICON .3. A TEMPERATURE STUDY IN THE ACID SYSTEM
CHEMICAL ETCHING OF SILICON .3. A TEMPERATURE STUDY IN THE ACID SYSTEM
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DOI：
10.1149/1.2428090
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发表时间：
1961-01-01
影响因子：
3.9
通讯作者：
ROBBINS, H
中科院分区：
文献类型：
--
作者：
SCHWARTZ, B;ROBBINS, H
在 0 至 50℃ 的温度范围内，研究了从 HF、HNO3、H~O 和 HC~I~O~ 系统中选择的各种成分溶液中硅的蚀刻速率。发现蚀刻过程的活化能在不同成分区域中是不同的。在高 HNO~ 区域，观察到大约 4 kcal/mol 的值，并将其解释为扩散控制反应的特征。在含有H~O或HC~H~O~稀释剂的组合物中，活化能增加，并且发现两个值。在高 HF 区域中，还观察到两个值，一个在 10-14 kcal/mole 范围内，另一个在约 20 kcal/mole 范围内。讨论了不同活化能值的意义。硅在硝酸和氢氟酸溶液中的溶解是一个复杂的反应。作者研究了该反应在恒温下的动力学 (1, 2)，并通过绘制蚀刻速率与蚀刻剂成分的函数关系，可以对系统的蚀刻行为提出定性解释。然而，不可能将速率数据拟合到在蚀刻剂成分的有限范围内有效的数学关系中。部分原因是反应的非均质性导致无法了解反应物的实际浓度和反应表面的温度。氮的复杂化学性质进一步掩盖了动力学，氮一方面为氧化反应的进行提供了数条平行路径，另一方面又受到自催化作用。鉴于这些复杂性，人们认为需要对反应进行进一步研究，为此，作者选择研究反应的速率温度依赖性。选择用于研究的蚀刻溶液的成分如图 1 所示。四种成分是从高硝酸区域中选择的，其中 HF 是已知的动力学上重要的试剂。在已知硝酸浓度起速率决定作用的高 HF 区域中选择了三种组合物。还在富含稀释剂的区域选择蚀刻剂，其中恒定蚀刻速率轮廓的曲率指示速率确定过程的变化。无蚀刻-
The etch rate of silicon in solutions of various compositions selected from the system HF, HNO3, H~ O, and HC~ I~ O~ has been investigated over the temperature range 0 to 50~ The activation energy of the etching process has been found to be different in the different composition regions. In the high HNO~ region values of about 4 kcal/mole have been observed and interpreted as characteristic of a diffusion governed reaction. In compositions containing H~ O or HC~ H~ O~ diluents the activation energy increases, and two values are found. In the high HF region two values are also observed, one in the range of 10-14 kcal/mole, and the other in the range of about 20 kcal/mole. The significance of the various values of the activation energy is discussed.The dissolution of silicon in solutions of nitric acid and hydrofluoric acid is a complicated reaction. The authors have studied the kinetics of this reaction at constant temperature (1, 2), and by plotting the etch rates as a function of the composition of the etchant, it was possible to propose qualitative explanations of the etching behavior of the system. However, it was not possible to fit the rate data into mathematical relationships that were valid over even limited ranges of composition of etchant. In part this was the result of the heterogeneous nature of the reaction, which precluded knowledge of the actual concentrations of reactants and the temperature that prevailed at the reacting surface. The kinetics are further obscured by the complicated chemistry of nitrogen which, on the one hand, provides several parallel paths for the oxidation reaction to proceed and, on the other hand, is subject to autocatalysis. In view of these complications, it was deemed desirable to subject the reaction to further study and, for this purpose, the authors have elected to investigate the ratetemperature dependence of the reaction. The compositions of the etching solutions selected for study are shown in Fig. 1. Four compositions were selected from the high nitric acid region where HF is known to be the kinetically important reagent. Three compositions were selected in the high HF region where nitric acid concentration is known to be rate determining. Etchants were also selected in the areas rich in diluent where the curvature of the constant etch rate contours was indicative of a change in the rate-determining process. No etch-