Impact of Si precursor mixing on the low temperature growth kinetics of Si and SiGe

Abstract

I have quantified, in a 300 mm ASM Epsilon 3200 tool, the impact of adding SiH 4 or SiH 2 Cl 2 to Si 2 H 6 on the low temperature growth kinetics of Si and SiGe. Increasing the amount of Si atoms by adding the formers to the latter resulted in Si growth rates (GR) reductions (i) at 20 Torr, in the 500 °C-575 °C range and (ii) at 525 °C, in the 20-90 Torr range. Those GR decreases were more pronounced with SiH 2 Cl 2 than with SiH 4 . I have otherwise investigated the 525 °C, 20 Torr growth kinetics of SiGe with germane (GeH 4 ) as the Ge source and various mixes of Si precursors. The GR associated with a SiH 2 Cl 2 +GeH 4 chemistry was lower than the Si 2 H 6 +SiH 2 Cl 2 +GeH 4 GR, which was itself lower than the Si 2 H 6 +GeH 4 one. Meanwhile, the Ge content was much higher with SiH 2 Cl 2 +GeH 4 than with Si 2 H 6 +SiH 2 Cl 2 +GeH 4 . The later was itself ∼1% to ∼4% higher than the Si 2 H 6 +GeH 4 one depending on the GeH 4 flow. As for pure Si, Si 2 H 6 governed the SiGe growth kinetics, with SiH 2 Cl 2 acting as if it was a source of HCl (GR reduction and slight Ge content increase). The situation was more complex when adding SiH 4 to Si 2 H 6 +GeH 4 . The Si 2 H 6 +SiH 4 +GeH 4 GR was always lower than the Si 2 H 6 +GeH 4 one. Meanwhile, the SiH 4 +GeH 4 GR was either lower or higher than the other two depending on the GeH 4 flow. The Ge content was significantly higher with SiH 4 +GeH 4 than with Si 2 H 6 +SiH 4 +GeH 4 (27%-53% range ⇔ 9%-32% range). The latter was itself ∼2% lower than the Si 2 H 6 +GeH 4 one. As before, Si 2 H 6 governed the SiGe growth kinetics, with SiH 4 slightly reducing both the GR and the Ge content, which is unusual. Plotting the SiGe GR as functions of the Ge concentration showed that the addition of SiH 4 or SiH 2 Cl 2 molecules did not dramatically change the SiGe growth kinetics, which was predominantly governed at 525 °C, 20 Torr by Si 2 H 6 .

Silicon epitaxial growth accelerated by parallel Langmuir processes using SiH2Cl2 and SiH3CH3 gases

“…Accounting for the parallel processes consisting of multiple precursors in various fields [17][18][19][20][21][22][23][24], the parallel-Langmuir process for the silicon epitaxial growth in a SiH2Cl2-SiHx-H2 system is assumed, as shown in Fig. 1, similar to that in the SiHCl3-SiHx-H2 system [6][7][8].…”

“…Accounting for the parallel processes consisting of multiple precursors in various fields [17][18][19][20][21][22][23][24], the parallel-Langmuir process for the silicon epitaxial growth in a SiH 2 Cl 2 -SiH x -H 2 system is assumed, as shown in figure 1, similar to that in the SiHCl 3 -SiH x -H 2 system [6][7][8]. In order to focus on the rate process governing the growth rate, the surface reactions and their reaction rates are assumed based on the following equations.…”

“…For expanding the application of this concept, the SiH 2 Cl 2 gas [1,[9][10][11] should be studied as to whether it showed a behavior similar to the SiHCl 3 gas, because it was also a major precursor for the silicon epitaxial growth. Although the combination of SiH 2 Cl 2 and SiH 4 was mainly evaluated by the plasma enhanced chemical vapour deposition (PECVD) [12][13][14][15][16], the thermal CVD process has been scarce [17][18][19][20].…”

Ultra-High Boron Doping of Si and Ge for Nanoelectronics and Photonics

“…Meanwhile, SiH4 or GeH4 molecules will have to find sites free from H atoms to adsorb and decompose, which is increasingly difficult as the temperature decreases. This results, for given Si or Ge growth rates and the same atomic flows, in temperatures typically 100°C lower achievable with Si2H6 or Ge2H6 than with SiH4 or GeH4 (6)(7). Temperature lowering and the use of higher order Si or Ge precursors seems to have a beneficial impact on boron incorporation.…”

Very low temperature growth of GeSi alloys with digermane, disilane and dichlorosilane

“…The same reactions, with Si instead of Ge, were used in Refs. [13][14][15] to explain, for Si2H6, the sharp Si growth rate increase with temperature up to 575°C (with a 53 kcal. mol.…”