Surface chemistry of group 11 atomic layer deposition precursors on silica using solid-state nuclear magnetic resonance spectroscopy
Bibliographic record
Abstract
The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using 13C, 31P, and quantitative 29Si nuclear magnetic resonance spectroscopy (NMR). Two copper metal precursors, 1,3-diisopropyl-imidazolin-2-ylidene copper (I) hexamethyldisilazide (1) and 1,3-diethyl-imidazolin-2-ylidene copper(I) hexamethyldisilazide (2), and one gold metal precursor, trimethylphosphine gold(III) trimethyl (3), are examined. Compounds 1 and 2 were found to chemisorb at the hydroxyl surface-reactive sites to form a ||–O–Cu–NHC surface species and fully methylated silicon (||–SiMe3, due to reactivity of the hexamethyldisilazane (HMDS) ligand on the precursor) at 150 °C and 250 °C. From quantitative 29Si solid-state NMR (SS-NMR) spectroscopy measurements, it was found that HMDS preferentially reacts at geminal disilanol surface sites while the copper surface species preferentially chemisorbed to lone silanol surface species. Additionally, the overall coverage was strongly dependent on temperature, with higher overall coverage of 1 at higher temperature but lower overall coverage of 2 at higher temperature. The chemisorption of 3 was found to produce a number of interesting surface species on HSAS. Gold(III) trimethylphosphine, reduced gold phosphine, methylated phosphoxides, and graphitic carbon were all observed as surface species. The overall coverage of 3 on HSAS was only about 10% at 100 °C and, like the copper compounds, had a preference for lone silanol surface reactive sites. The overall coverage and chemisorbed surface species have implications to the overall growth rate and purity of metal films grown with these precursors.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".