Characterization and Control of Silicon Surface Modification Produced by CCl4 Reactive Ion Etching

Abstract

The work constitutes a survey of CCl4‐normalbased reactive‐ion‐etching‐induced surface modification in silicon. The damage produced during reactive ion etching (RIE) is studied using a diverse set of techniques, such as spreading resistance, metal‐semiconductor contacts, electron spin resonance, and reflected high energy electron diffraction. The surface chemistry was also investigated through the use of Auger electron spectroscopy. Among the possible effects that could be produced by RIE (structural damage, impurity and etching ion permeation, and coating residue or film formation), the bulk of the evidence points to structural (bonding) damage with its associated positive charge, as being the dominant surface modification caused by CCl4 , or CCl4+normalHe etching for the process parameters used in this study. The evolution of this damage with varying etching parameters is also examined. Further, a survey of various dry processes that can be used to overcome or reverse the surface modification occurring during RIE is made. Specifically, we show that hydrogen passivation, low temperature (∼600°C for times ≳ 1h) furnace anneals, or rapid thermal anneals (1100°C for 10s) can be used to restore the properties of the RIE‐damaged silicon surface. A criterion for the efficacy of rapid thermal annealing in restoring surface properties after RIE involving other gases is postulated.

Removal of Fluorocarbon Residues on CF 4 / H 2 Reactive‐Ion‐Etched Silicon Surfaces Using a Hydrogen Plasma

“…Formation of voids in the amorphized region of the damaged silicon would decrease its refractive index toward the value of c-St and account for the observed recovery of optical properties. Even though the substrate optical properties have recovered, the damage is still present (5)(6)(7)(8)(9)(10)(11)20). The state of the surface at this point is shown schematically in Fig.…”

“…XPS results showed the deposited material to be carbon and oxidation of the surface. The dc selfbias voltage is also higher at low pressure, leading to more energetic ion bombardment and the probability of introducing more substrate damage (9,10,20). Other samples were cleaned with a source of oxygen present in an attempt to decrease the carbon contamination concentration.…”

“…The high selectivity of this process is due to the formation of a fluorocarbon film on silicon which passivates the surface and prevents it from being etched (4). Figure 1, a diagram of a silicon surface modified by RIE exposure, shows this fluorocarbon film along with the substrate alterations caused by ion bombardment damage, implantation, and hydrogen permeation (4)(5)(6)(7)(8)(9)(10). It has been demonstrated that these modifications degrade the electrical performance of the substrate making it advantageous to develop new processes which will prevent, restore, or improve surfaces degraded by RIE exposure (6)(7)(8)(9)(10)(11)(12)(13)(14).…”

Surface characterization

“…The actual silicides and Schottky barrier metalizations are thin films which are listed separately in Table VIII. The vapor-phase interaction between silicon and molecular gases is another topic showing strong on-going interest for etching (354,442,474,478), oxidation (435,547), and deposition (51,362,526). Epitaxial growth of semiconducting (45, 136, 323,469,510) and insulating (215,274) layers on silicon substrates is another area of strong interest.…”

Highly Sensitive Impurity Analysis of GaAs Using SIMS and Chemical Preparation

“…Manuscript submitted June 10, 1985; revised manuscript received Oct. 14, 1985." This was Paper 453 presented at the New Orleans, Louisiana, Meeting of the Society, Oct. [7][8][9][10][11][12] 1984.…”