Effects of dry etching on the electrical properties of silicon

Abstract

Growth and electrical characteristics of palladium silicide contacts on dry-etched silicon surfacesDry etching results in the permeation of silicon by etching species; it also results in the better understood residue layer formation and near-surface lattice damage layer formation. The principal species permeating silicon during dry etching exposures is found to be hydrogen. Using doping deactivation as a marker, we study this permeation and show that hydrogen can permeate as much as 10 fl during etching, thereby modifying the electrical properties ofSi to that depth. We further demonstrate that this hydrogen permeation, at least in the case of p material, exhibits two distinct regions of behavior and two apparent diffusion coefficients. It is also shown that the doping deactivation anneals out differently in these two permeation regions.

Plasma etching: Yesterday, today, and tomorrow

“…236)], C 2 F 6 (Freon 116), and C 3 F 8 (Freon 218) were used in the early days to etch SiO 2 , 28,29 usually with addition of O 2 when selectivities to resist and/or silicon were not critical, and polymer control was important. Hydrogen addition to the above fluorocarbons was used to increase selectivity to silicon, 28,29,237 with the drawbacks of polymer formation, decreased etch rate, 237,238 and deep penetration of hydrogen into the silicon substrate [239][240][241][242][243][244][245][246][247] that can lead to device degradation if not annealed properly. In applications where this is not an issue (such as patterning of waveguides), hydrogen may be used as an additive to control selectivity to silicon and/or photoresists.…”

An Overview of Dry Etching Damage and Contamination Effects

“…The first demonstration that this hydrogen permeation effect is present in dry etching showed that hydrogen at the atomic percent level permeated 400A beneath a CFgH2-etched Si surface (17). Subsequent studies of hydrogen permeation during dry etching have showed the surprising result that hydrogen can actually permeate microns below an etched surface at concentrations sufficient to cause significant dopant deactivation (18,20,22,49). Very recent work has established that this hydrogen permeation can take place through both n-type and p-type Si (50).…”

“…In fact, damage is often inherent in these processes due to the presence of ion bombardment, which can create bonding damage in semiconductors and insulators (1-9, 11, 13), as well as due to the presence of UV radiation, which can create bonding damage in insulators (10). Contamination is also often inherent in these processes due to the presence of residue layers made up of reactant species and reaction products and due to the presence of impurities which may permeate the etched material during the dry etching exposure (3,4,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). These damage and contamination effects that can be inherent in dry etching are shown schematically in the model of Fig.…”

“…Dry etching damage and contamination effects manifest themselves in a number of ways in etched dielectrics from shifts in neutral trap densities and positive charge (10) to increased leakage currents (25). Dry etching effects manifest themselves in etched silicon in changes in surface properties (4), in changes in generation lifetimes (12), in changes in doping activation (20)(21)(22)(23), and can even result in changes in diffusion lengths (26). Subsequent processing steps on a silicon surface, from silicidation (27) to oxidation (19), can be impacted if the reacting surface has been exposed to prior dry etching.…”

Random and Uniform Reactive Ion Etching Texturing of Si

“…It is known that reactive ion etching techniques produce surface damage [15][16][17][18]. Various surface passivation techniques have been investigated in reducing RIE damage [15,19].…”