Real-time, in situ monitoring of surface reactions during plasma passivation of GaAs

Abstract

Real-time, in situ observations of surface chemistry during the remote plasma passivation of GaAs is reported herein. Using attenuated total reflection Fourier transform infrared spectroscopy, the relative concentrations of-As-O,-AsH ,-H,O, and-CHz bonds are measured as a function of exposure to the effluent from a microwave discharge through NH,, NDs, Hz, and D,. The photoluminescence intensity (PL) from the GaAs substrate is monitored simultaneously and used qualitatively to estimate the extent of surface state reduction. It was found that, while the-CH,(x = 2,3) and-As-O concentrations are reduced rapidly, the rates at which the-AsH concentration and the PL intensity increase are relatively slow. The concentration of-HZ0 on the GaAs surface increases throughout the process as surface arsenic oxides and the silica reactor walls are reduced by atomic hydrogen. These observations suggest that removal of elemental As by reaction with H at the GaAs-oxide interface limits the passivation rate.

Analysis of mechanism of carbon removal from GaAs(100) surface by atomic hydrogen

“…This yields the real desorption products during H irradiation. Here we see that the water species at m/e equal to 17 and 18 have been canceled, in agreement to literature [40][41][42] that the water species are not true desorbing species at room temperature. In contrast, the peaks at mass numbers characteristic of the CH 4 molecule are clearly visible and are summarized in Table 2.…”

Hydrogen-induced changes in the breakdown voltage of InP HEMTs

“…Similar results have been observed on AlGaAs surfaces [10]. As postulated in [10], the adsorption of H onto the oxidized semiconductor can lead to the formation of volatile AsH with H O as a byproduct [10], [12]. The volatile AsH desorbs, leaving H O on the surface [11].…”

“…Physisorbed H O on InGaAs substrates has been shown to lead to additional cation oxidation and further AsH desorption [10], [12]. In the case of InAlAs surfaces, physisorbed H O could result in the formation of additional Al O or In O .…”

Chemical investigations of GaAs wafer bonded interfaces

“…This reduced room temperature bond strength is believed to be due to modifications of the BSG surface during the prebonding treatment. 18 The DI H 2 O rinsing prebonding step on the BSG preferentially removes B 2 O 3 from the near surface region of high boron content BSGs leaving a potentially porous structure on the surface. The altered oxide structure may change the amount of OH groups available for surface bonding interactions without changing the total number of groups detected by IR measurements.…”

“…Other studies indicate that the final DI water rinse prior to bonding selectively removes B 2 O 3 from the near surface region of the 30 mole % B 2 O 3 BSG leaving a SiO 2 -rich and possibly a more porous surface. 18 This possible surface porosity may provide more space for the accommodation of evolved species and, therefore, modify the evolution of H 2 O/OH species for the two types of glassbonded samples.…”