Tribological behavior of polycrystalline and single-crystal silicon

Abstract

SEM tribometric experiments were performed with polycrystalline silicon (poly-Si) vs. poly-Si and Si(111) vs. Si(111) interfaces in moderate vacuum to 850~ complementing similar recent experiments on Si(100) vs. Si(100). All friction data agree with a hypothesis associating the wear-and thermal desorption-induced generation and cooling-induced adsorptive passivation of dangling bonds on the sliding surfaces with high and low adhesion and friction, respectively. Strong additional evidence is given for a surface re-and deconstruction-induced, temporary reduction in high temperature friction. The wear rate of the various Si vs. Si specimens (on the order of 10 -12 m 3/(N m)) specific to the wide temperature range vacuum test regimen is about 104 times higher than that of unpolished PCD films sliding against themselves under multi-GPa unit loads and similar environmental conditions. In contrast, the characteristic load-carrying capacity of the high-wearing Si, regardless of its crystal structure, was found to be only ,,~ 1 MPa. The wear mechanism of the various Si crystallinities was heavily influenced by the agglomeration and plowing of the wear debris particles trapped in the contact zone.

Mechanisms for fatigue and wear of polysilicon structural thinfilms

“…MUMPs process [5,6]. Muhlstein, Brown, and Ritchie ( Figure 2.2 [7]) utilized the same design for their single-crystal boron doped silicon testing, although instead of using precracked beams to investigate crack propagation [1,4], they employed a notched cantilever beam (with a 1 µm root radius) to permit the investigation of both initiation and growth of small flaws. Muhlstein, Brown, Stach and Ritchie [8][9][10][11] and Shrotiya, Allameh, Soboyejo and coworkers [12][13][14][15] also used this resonator design for the testing of thinfilm polysilicon.…”

“…Silicon, however, is quite brittle and subject to several reliability concerns -most importantly, stiction [1,2], wear [1,3] and fatigue -that can limit the utility of silicon MEMS devices in commercial and defense applications. Currently, there are many commercial silicon-based MEMS devices that are subjected to various environments and forms of periodic loading, sometimes at very high frequency, such as resonators found in both radio frequency as well as MEMS sensor applications.…”

“…This is largely a result of the ease with which silicon can be microfabricated to produce complex mechanical structures in thin film form, because of highly developed processing methods directly related to semiconductor electronics processing [1,2]. However, as was also illustrated earlier, silicon is not an ideal structural material; it is quite brittle and subject to several reliability concerns -most importantly, stiction [3,4], wear [3,5] and fatigue [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] -that strongly limit the utility of silicon MEMS devices in commercial and defense applications.…”

“…features that have both electrical and mechanical components. The mechanical parts of these systems are fabricated using thin film fabrication technologies similar to the fabrication technologies used in the integrated circuit (IC) industry [1]. This allows easy integration of fabrication of electrical and mechanical parts on one chip.…”

Simulation and experiments on friction and wear of diamond: a material for MEMS and NEMS application

“…A more thorough description of the apparatus and procedures for examining PCD and Si in vacuum may be found in [14]. The equivalent methods for testing a variety of materials in partial pressures of H 2 and O 2 were previously described in [8,9] and [11], respectively. A constantly exchanged gas environment maintained at a given partial pressure offers several benefits to testing PCD.…”