PECVD Silicon Nitride Passivation on Boron Emitter: The Analysis of Electrostatic Charge on the Interface Properties

Abstract

The dependence of surface recombination of boron diffused and undiffused silicon surfaces passivated with a-SiN x :H on the net charge density is investigated in detail. The films are deposited by plasma-enhanced chemical vapour deposition using a 2.45 GHz microwave remote plasma system. The surface charge density on the samples is varied by depositing charge using a corona discharge chamber. Excess carrier lifetime, capacitance-voltage, and Kelvin probe measurements are combined to determine the surface recombination velocity and emitter saturation current density as a function of net charge density. Our results show that the application of negative charge causes a substantial reduction in the surface recombination of samples with boron diffused emitters, even for high boron surface concentrations of 5×10 19 cm −3 . The significant difference observed in surface recombination between boron diffused and undiffused sample under accumulation implies that the presence of boron diffusion has results in some degradation of the Si-SiN x interface. Further, (111) oriented surfaces appear more sensitive to the boron surface concentration than (100) oriented surfaces.

Extremely low surface recombination velocities on low‐resistivity n‐type and p‐type crystalline silicon using dynamically deposited remote plasma silicon nitride films

“…Table summarises the Q eff and S eff.max data obtained for SiN x in this work compared with other remote plasma SiN x films. The Q eff of +8 × 10 12 cm −2 found in this work for nearly stoichiometric SiN x films is significantly higher than previously published values obtained for as‐deposited SiN x films using a similar PECVD reactor. Theoretically, it was shown that, for high charge densities (>5 × 10 11 cm −2 ), the surface recombination rate ( U ) is inversely proportional to the square of the fixed charge density ( Q f ), that is, U ≈ 1/| Q f | 2 .…”

Characterization of boron surface doping effects on PECVD silicon nitride passivation

“…The high temperature anneal results in a densification and modification of the electrical properties of the nitride film. This trend is also suspected to be the continuation of the trend observed during C-V measurement where anneal at 400°C resulted in a substantial reduction on hysteresis [8]. Hence, annealing 978-1-4244-5892-9/10/$26.00 ©201 0 IEEE at high temperature may cause further densification and increase in charge transfer barrier, causing the charge injection into and out of the film becomes more difficult.…”

“…(4) <eif <b W Negative charges were initially depOSited followed by charge removal in isopropyl alcohol (IPA) solution and deposition of positive charges. The starting point in each graph hereafter, prior to any charging, is given by Qf that is determined from CV measurements in the dark [8], while the applied surface charge density (from corona charging)…”

Extracting surface recombination parameters of germanium–dielectric interfaces by corona-lifetime experiments

“…This is low compared to the samples Bonilla et al presented (Q f = + 2.2 × 10 12 and Q f = +2.6 × 10 12 cm −2 ), but in line with the work of Haug et al (Q f ≈ + 0.65 × 10 12 cm −2 ) and in general not uncommon for SiN x with x ≈ 1. 87,88 The pristine surface recombination velocity of our sample is S eff ≈ 53 cm s −1 . This is in the same order of magnitude as Bonilla et al and Haug et al presented.…”