Microwave‐Discharge Plasma Oxidation of Silicon in a Cusp Magnetic Field

Abstract

The role of oxygen radicals and ions in the plasma oxidation of silicon is investigated using microwave-discharge oxygen plasma ignited in a cusp magnetic field. The cusp magnetic field forces streaming plasma to stop its progress resulting in a plasma boundary formation. Probe measurement of argon plasma reveals that the original plasma density of 2 • 10 l~ cm 3 decreases to one-third, 6 • 109 cm -3, across the boundary. Thus, the cusp magnetic field achieves an oxygen plasma with fewer ambient charged particles. However, it is found that oxide growth rate on silicon does not change across the boundary. These results seem to imply that oxide, growth is not directly dominated by oxygen ions supplied from the plasma, but that oxygen atoms cause the oxide growth in plasma oxidation.

Low‐power r.f. plasma oxidation of aluminium

“…Studies of the oxidation mechanism indicate that silicon also grows in an oxygen plasma via anion migration from the oxide/gas interface and is a network-former. 66,69,70 Several authors have indicated that the migrating species is O and the reduced size of the ion, relative to the oxygen molecule, contributes to the reduction in activation energy and increase in oxidation rates observed in plasma work. 66,71 -74 The geometry of the plasma electrodes used in these oxidation studies supports the production of anions; this is based on Eqn.…”

Plasma-assisted oxidation, anodization, and nitridation of silicon

“…The most extensively studied configuration is the electron cyclotron resonance (ECR) reactor, depicted schematically in Figure 5 [44]. Initial studies were performed under floating potential conditions at 0.2 mTorr O^ [45][46][47]. Oxidation-rate data were not consistent with either the Deal-Grove (linear-parabolic) model [48] or a power-law model, but were analyzed according to the kinetic model proposed by Cabrera and Mott [49].…”

Device quality low temperature gate oxide growth using electron cyclotron resonance plasma oxidation of silicon

“…Widely adopted model form Deal-Grove for thermal oxidation, does not fit well with the growth results observed during the ECR plasma oxidation. Kimura et al [8], [9] explained the ECR plasma oxidation growth results using Mott-Cabrera model [38]. This model assumes the movement of metal ions responsible for the thin metal oxidation layer.…”

“…Several groups have reported the electron cyclotron resonance (ECR) plasma assisted oxidation of silicon [8][9][10][11][12][13][14][15][16][17][18][19][20]27]. Si wafers were successfully oxidized from room temperature to up to 640 o C using ECR plasma [8][9][10][11][12][13][14][15][16][17][18][19][20]. Oxide has been grown in a floating substrate and also with an applied external bias.…”

“…Defect density and oxide breakdown strength has been reported to be in the range of 1.2x10 10 and 5-20 MV/cm respectively [12]. Chemical composition was studied using XPS and found to be fairly close to thermally grown silicon dioxide [9]. Actual growth mechanism still remains unknown; although many groups believe that it is because of the transport of Oions through the growing oxide layer, as suggested by the higher growth rates achieved when substrate was biased positively [12].…”