Near‐surface damage and contamination of silicon following electron cyclotron resonance etching

Abstract

Articles you may be interested inThermal anneal activation of near-surface deep level defects in electron cyclotron resonance hydrogen plasmaexposed silicon J. Vac. Sci. Technol. B 15, 226 (1997); 10.1116/1.589269 Damage and contamination in lowtemperature electron cyclotron resonance plasma etching Damage formed by electron cyclotron resonance plasma etching on a gallium arsenide surface Damage and contamination produced after electron cyclotron resonance (ECR) etching of Si using CF 4 gas has been studied using electrical characterization, Rutherford backscattering spectroscopy (RBS), secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and etch pit density measurement techniques. Due to the sman dc self-bias voltage generated across the pla..<;ma sheath, ECR etching is expected to produce low damage and contamination levels. RBS measurements show that ECR etching does indeed produce less structural damage than that produced by conventional reactive ion etching (RIE). It is found that the damage and contamination levels from an ECR etching process are actually reduced by the addition of radio frequency (rO power to the wafer. The metallic impurity levels are shown to be greatly reduced by covering the stainless steel wall of the ECR source near the resonance region with an anodized Al liner. The plasma density in the resonance region of the reactor during ECR processes is much higher than that during RIE processes. Therefore, the ECR processes produce heavy metal contamination, which is mainly from the portion of the stainless steel wall of the reactor in contact with the plasma. Schottky diodes fabricated on the etched samples exhibit high leakage currents implying some damage and/or impurities are present in the near-surface region. Relationships that exist among the generation current of the metal-oxide-silicon (MOS) capacitors, the etch pit density and the metallic impurity level were studied. Some wafers were exposed to an Ar ECR/RIE plasma to compare the effects of pure physical sputtering and ion-assisted chemical etching, as when CF" was used. A possible explanation for the observed behavior is given.

Etch characterization of an electron cyclotron resonance process reactor

“…22 The length of the ECR source is 39 cm; the diameter and length of the RIE chamber are 48 and 51 em, respectively. The inner diameter of the ECR source is 13.2 cm when an anodized aluminum liner is used.…”

Depth distribution of plasma induced damage and dislocation generation due to an interaction of subsequent oxidation

“…1,2 Oehrlein et al have found that two nearsurface damage layers were formed under a fluorocarbon film deposited on the surface. It is known, however, that RIE induced damage and contamination occur when Si substrates are exposed to a high flux of energetic ion bombardment in plasma.…”

Time dependence of etch-induced damage generated by an electron cyclotron resonance source

“…3 The competition between creation and removal of damage by dry etching determines whether the devices will have low damage or not. 6,9,10 Slow etching of Si has been shown to lead to accumulation of damage 10,11 while faster etch rates for GaAs have been shown to lead to a denser but shallower damage layer near the surface. 6 Etching damage extends deeper than the predicted ion stopping range due to both defect diffusion [7][8][9]12 and ion channeling 8,13 during etching.…”