The Conversion of Czochralski Silicon from P-Type to N-Type by Hydrogen Plasma Enhanced Thermal Donor Formation

Abstract

Our experiments show a hydrogen plasma assisted creation of p-n junctions in p-type Cz silicon due to a hydrogen enhanced thermal donor (TD) formation at temperatures ≤450 °C. Applying DC or HF plasma treatments a conversion of p-type into n-type Cz silicon by TD formation occurs. One can distinguish one step processes (p-n junction formation appears just after the plasma exposure) and two step processes (p-n junction formation requires subsequent post hydrogenation annealing). The samples are studied by depth resolved spreading resistance probe (SRP), capacitance-voltage (CV) and Hall measurements. For the one step processes a kinetic model for hydrogen enhanced TD formation is presented.

What Do We Know about Hydrogen-Induced Thermal Donors in Silicon?

“…However, numerous studies have demonstrated the thermal stability of different kinds of STDs up to temperatures well above 450°C; [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][43][44][45][46][47] thus, we discard this possibility here. Passivation corresponds with a further reaction, for example given by H + HX ⇔ H 2 X, if the STDH center ͑HX͒ is a single donor.…”

“…Hydrogenation-induced donor formation in p-type silicon.-In p-type hydrogenated silicon, the introduction of STDs yields a type of conversion, whereby the p-n junction moves along with the hydrogen diffusion front. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] Consequently, the junction profile is not abrupt but rather linear as illustrated by Fig. 1, which should be taken into account when deriving carrier concentration profiles from C-V and OTD concentrations from DLTS measurements.…”

“…These centers can be exploited for the low temperature formation of deep p-n junctions in p-type CZ silicon. [14][15][16][17][18][19][20][21][22][23][24] An example is shown in Fig. 1, for a 12 h, 260-270°C H-plasma-treated 5 ⍀ cm p-type CZ Si sample, showing conversion to n-type in the first 50 m from the exposed surface.…”

What do We Know About Hydrogen-Induced Thermal Donors?

“…In p-type hydrogenated silicon, the introduction of STDs yields a type conversion, whereby the p-n junction moves along with the hydrogen diffusion front [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Consequently, the junction profile is not abrupt but rather linear as illustrated by Fig.…”

“…At the same time, hydrogen-related Shallow TDs (STDHs) have also been observed [7][8][9][10][11][12][13], with ionization energies in the range 35-40 meV and infrared absorption peaks in the sub 300 cm -1 range typically. These centers can be exploited for the low-temperature formation of deep p-n junctions in p-type Cz silicon [14][15][16][17][18][19][20][21][22][23][24]. An example is shown in Fig.…”