Exfoliation and blistering of Cd0.96Zn0.04Te substrates by ion implantation

Abstract

As part of a series of wafer bonding experiments, the exfoliation/blistering of ion-implanted Cd 0.96 Zn 0.04 Te substrates was investigated as a function of postimplantation annealing conditions. (211) Cd 0.96 Zn 0.04 Te samples were implanted either with hydrogen (5 ϫ 10 16 cm Ϫ2 ; 40-200 keV) or co-implanted with boron (1 ϫ 10 15 cm Ϫ2 ; 147 keV) and hydrogen (1-5 ϫ 10 16 cm Ϫ2 ; 40 keV) at intended implant temperatures of 253 K or 77 K. Silicon reference samples were simultaneously co-implanted. The change in the implant profile after annealing at low temperatures (Ͻ300°C) was monitored using high-resolution x-ray diffraction, atomic force microscopy (AFM), and optical microscopy. The samples implanted at the higher temperature did not show any evidence of blistering after annealing, although there was evidence of sample heating above 253 K during the implant. The samples implanted at 77 K blistered at temperatures ranging from 150°C to 300°C, depending on the hydrogen implant dose and the presence of the boron co-implant. The production of blisters under different implant and annealing conditions is consistent with nucleation of subsurface defects at lower temperature, followed by blistering/exfoliation at higher temperature. The surface roughness remained comparable to that of the as-implanted sample after the lower temperature anneal sequence, so this defect nucleation step is consistent with a wafer bond annealing step prior to exfoliation. Higher temperature anneals lead to exfoliation of all samples implanted at 77 K, although the blistering temperature (150-300°C) was a strong function of the implant conditions. The exfoliated layer thickness was 330 nm, in good agreement with the projected range. The "optimum" conditions based on our experimental data showed that implanting CdZnTe with H ϩ at 77 K and a dose of 5 ϫ 10 16 /cm 2 is compatible with developing high interfacial energy at the bonded interface during a low-temperature (150°C) anneal followed by layer exfoliation at higher (300°C) temperature.

Materials Issues for the Heterogeneous Integration of III-V Compounds

“…[22][23][24] The wide difference in materials properties among these examples (and complementary work on Si [25], SiC [26], and CdZnTe [27]) demonstrate that an understanding of exfoliation processes leads to improved layer transfer schemes for a wide variety of semiconductor materials.…”

Ion Implantation-Induced Layer Splitting of Semiconductors

“…H-implantation-induced surface blistering/exfoliation study is also extended to ternary semiconductors like CdZnTe (Miclaus et al, 2005). Again, the main motive of these studies is to find out the possibilities of the layer transfer of CdZeTe depending upon its constituents molar concentration.…”

The Phenomenology of Ion Implantation-Induced Blistering and Thin-Layer Splitting in Compound Semiconductors

“…In the case of Cd 0.96 Zn 0.04 Te, Miclaus et al performed blistering/exfoliation investigations after hydrogen implantation and annealing. 74 H-implantation was carried out with different ion energies of 40 keV to 200 keV while keeping the implantation temperature at 253 K or 77 K. The ion dose used for the implantation was 5 9 10 16 H + cm -2 . It was observed that samples that were implanted at The Phenomenology of Ion Implantation-Induced Blistering and Thin-Layer Splitting in Compound Semiconductors 253 K did not show any surface blistering even after having been annealed at up to 500°C.…”