Thermal stability of vapor phase deposited self-assembled monolayers for MEMS anti-stiction

Abstract

Six different source chemicals (organosilanes) were successfully used for deposition of self-assembled monolayers (SAMs) onto silicon substrates by a vapor phase process. Five different fluorocarbon coatings and one hydrocarbon coating were deposited. The thermal stability of the coatings was studied in detail with respect to degradation as a function of temperature, and for the fluorocarbon coatings also the degradation rate at 400 • C. For fluorocarbon coatings deposited from FDTS a useful lifetime of approximately 90 min at 400 • C was found allowing the coating to survive high temperature MEMS packaging operations, while fluorocarbon coatings deposited from FOTS, FOMDS, FOTES and FOMMS were less stable. The hydrocarbon coating deposited from OTS degrades already at approximately 200 • C. The thermal stability of the SAM coatings was found to be significantly reduced if aggregations from the deposition process are present on the coatings.

Thermal stability of thiol and silane monolayers: A comparative study

“…1. The hydrophilic amine functionality is particularly useful for the assembly of various chemicals and biomaterials [14,25], while the hydrophobic/oleophobic perfluorinated alkyl chain has been associated with low surface energy and higher thermal stability [1,2,26]. The silane SAMs were prepared by immersing a freshly prepared hydroxylated silicon wafer in a 1 mM silane solution, prepared using anhydrous hexane as the solvent, for 16 h at room temperature.…”

“…For example, coatings for micro-electromechanical system (MEMs) applications require temperature ratings to 400 8C [1,2]. Furthermore, thermal stability is desirable for future molecular electronics applications [3], and SAMs that serve as patterned templates for polymers and biomaterials may need to withstand annealing temperatures.…”

Vapor-Phase Self-Assembled Monolayers for Anti-Stiction Applications in MEMS

“…• C. The degradation temperature is dependent on the coating quality since aggregations on the SAM coatings significantly reduce their thermal stability [35].…”

High‐Performance Microring Resonators Fabricated with Multiphoton Absorption Polymerization

“…The PDMS was poured onto a glass cover slip that had been treated with an oxygen plasma. A silicon wafer was treated overnight in an evacuated desiccator with (tridecafluoro-1,1,2,2-tetra-hydrooctyl)dimethylchlorosilane [30]. With a 200 mm thick spacer separating it from the glass slide, the wafer was then used to cover the PDMS.…”