Theoretical Study on the Decomposition Kinetics and Thermochemistry of Tetramethyldisilazane and Hexamethyldisilazane─Formation of Silanimine and Silene Species
Bibliographic record
Abstract
The gas-phase decomposition kinetics and thermochemistry of 1,1,1,3,3,3-hexamethyldisilazane (HMDSZ) and 1,1,3,3-tetramethyldisilazane (TMDSZ), two potential single-source precursors for the chemical vapor deposition of silicon carbonitride thin films, were systematically investigated using ab initio calculations at the B3LYP/6-311++G(d,p)//CCSD(T)/6-311++G(d,p) level of theory. Both concerted and stepwise decomposition routes for each molecule were examined, allowing for a comparison of the reactions involving the cleavages of common bonds of Si–C, Si–N, and N–H for the two molecules. A new set of reaction pathways open to TMDSZ due to the presence of a Si–H bond was also explored. It was found that all three bonds of Si–N, Si–C, and N–H could be broken more easily in TMDSZ than HMDSZ. Both HMDSZ and TMDSZ are capable of producing silene and silanimine species upon decomposition. In fact, the most kinetically and thermodynamically favorable pathways fall in the formation of these species. The concerted formation of 1-dimethylsilylaminosilene via the elimination of methane from TMDSZ is the most kinetically and thermodynamically favorable route between the two molecules with an activation barrier (ΔH0⧧) of 48.5 kcal mol–1 and reaction enthalpy (ΔH0) of 11.6 kcal mol–1, respectively. These values are lower than the corresponding lowest values in HMDSZ of ΔH0⧧ = 66.4 kcal mol–1 for the concerted production of 1,1-dimethylsilene and trimethylsilylamine and ΔH0 = 41.7 kcal mol–1 for the formation of CH4 and N-trimethylsilyl-1,1-dimethylsilanimine. Overall, this work has provided insights into the reactivity of the two molecules. It has been shown that TMDSZ is more reactive than its analog HMDSZ due to the presence of the Si–H bonds and reduced steric hindrance.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".