Selective epitaxial growth of boron- and phosphorus-doped Si and SiGe for raised sources and drains

Reduced pressure–chemical vapor deposition of high Ge content Si1−xGex and high C content Si1−yCy layers for advanced metal oxide semiconductor transistors

“…In order to calibrate the macroscopic loading effect (i.e. the strong growth rate increase when switching from blanket to patterned wafers [16,23]), we have proceeded with the selective epitaxial growth of nominally 10 nm of Si 0.65 Ge 0.35 or Si 0.53 Ge 0.47 on patterned, thinned down SOI wafers (t Si $10 nm, buried SiO 2 layer thickness $400 nm). A mesa isolation scheme was used for those patterned wafers, with Si openings inside SiO 2 occupying either 4% or 21% of the total wafer surface.…”

“…Suh and Lee [15] have demonstrated that, for a SiH 2 Cl 2 +GeH 4 chemistry, the gas flow ratio F(GeH 4 )/F(SiH 2 Cl 2 ) is linked to the Ge concentration through the following relationship: x 2 =ð1 À xÞ ¼ nðFðGeH 4 Þ=FðSiH 2 Cl 2 ÞÞ: We obtain a good fit of our SiH 2 Cl 2 +GeH 4 experimental data at 550 1C through this relationship, with a constant n equal to 2.66 for a F(SiH 2 Cl 2 )/ F(H 2 ) mass flow ratio of 0.0025. Were we to combine this n ¼ 2.66 value at 550 1C with those obtained at higher temperatures with exactly the same gaseous precursor flows and growth pressures (n ¼ 1.08 at 650 1C [16], n ¼ 0.66 at 700 1C [17] and n ¼ 0.55 at 750 1C [18]), the following relationship linking n to the absolute growth temperature T could be obtained: n (F( [17]. For given flows of SiH 2 Cl 2 and GeH 4 , the Ge concentration indeed steadily decreases as the growth temperature increases [17].…”

“…This quite well-known behavior (see Refs. [16][17][18] and references therein) is due to a lowering of the H surface coverage when a limited amount of Ge is present on the surface. The Ge atoms act as desorption centers, lowering the activation energy for hydrogen desorption from the growing surface (activation barriers for hydrogen desorption from Si(0 0 1): 47 kcal mol À1 [19], from Ge(0 0 1): 37 kcal mol À1 [20,21]).…”

“…3b is the rather low growth rates obtained (between 0.15 and 3.9 nm min À1 ). This means that (i) 550 1C is more or less the low growth temperature boundary when growing Si 1Àx Ge x in RP-CVD with SiH 2 Cl 2 and GeH 4 as gaseous precursors and (ii) adding some HCl (in order to promote selectivity versus dielectric materials such as Si 3 N 4 ) would most probably be problematic because of the severe growth reduction it induces [16][17][18].…”

Optimization of Selective Growth of SiGe for Source/Drain in 14nm and Beyond Nodes FinFETs

“…This type of epitaxy suffers from a problem so-called pattern dependency which yields to different SiGe profiles across the transistor arrays. This behavior occurs when the density and size of the transistor vary in a chip [13][14][15][16][17][18][19]. The reason behind the pattern dependency of SEG is non-uniform consumption of reactant gas molecules when the exposed Si area varies over the chip.…”