Peter Roitman

Electron spin resonance of separation by implanted oxygen oxides: Evidence for structural change and a deep electron trap

We present direct evidence for deep electron traps and structural changes in separation by implanted oxygen (SIMOX) buried oxides and evidence that some positively charged E’ centers are compensated by negatively charged centers in SIMOX oxides.

Observation of latent reliability degradation in ultrathin oxides after heavy-ion irradiation

Constant voltage time-dependent-dielectric-breakdown distributions were obtained for both unirradiated and irradiated 3.0 and 3.2 nm thick SiO2 films subjected to 60Co gamma irradiation and heavy ions of 823 MeV 129Xe (linear energy transfer=59 MeV-cm2/mg). The gamma irradiation had no effect on oxide lifetime. The heavy ion irradiation substantially reduced oxide life even though the devices were biased at 0.0 V during irradiation. The reduction of oxide lifetime under constant-voltage stress conditions was a strong function of the heavy ion fluence.

Dose dependence of microstructural development of buried oxide in oxygen implanted silicon-on-insulator material

The effect of implantation dose on microstructural development of the buried oxide (BOX) of 200 keV oxygen implanted Si was studied by electron microscopy. A continuous BOX layer with a low density of Si islands was obtained for a dose of 0.45×1018 cm−2, following high temperature annealing. At a lower dose of 0.225×1018 cm−2 a layer did not form, but only disjointed, isolated, oxide precipitates developed. At a higher dose, 0.675×1018 cm−2, a continuous BOX layer with a high density of Si islands formed. Microstructures of intermediate-temperature annealed samples showed the formation of oxide precipitates at preferred depths, the morphology being dose dependent. The final microstructure of the BOX is strongly influenced by the evolution of the oxide precipitates during annealing. A qualitative mechanism is proposed for the dose-dependent behavior of BOX formation during the annealing process.

Nano-defects in commercial bonded SOI and SIMOX

Two new classes of defects have been identified in commercial SIMOX, plasma thinned BSOI and BESOI materials. The first class of defects are revealed when the materials are treated in concentrated HF, and their density is in the range 10/sup 2/-10/sup 3/ cm/sup -2/. The second class of defects appear when the materials are etched by the enhanced Secco etch method. Contrary to the common belief defect densities of 10/sup 4/-10/sup 5/ cm/sup -2/ are present in both plasma thinned BSOI and BESOI after Secco etching. The defect densities in SIMOX after the Secco etching were 10/sup 6/-10/sup 7/ cm/sup -2/ which was expected.

Correlation between CMOS Transistor and Capacitor Measurements of Interface Trap Spectra

The radiation-induced change in the energy spectra of SiO2-Si interface traps as determined using the charge-pumping and weak-inversion techniques on CMOS transistors and using the quasi-static C-V and detailed model techniques on CMOS capacitors are compared. Over the range of approximately 1010 to 1012 cm-1 eV-1, good quantitative agreement is obtained between these methods.

Breakdown mechanism in buried silicon oxide films

Charge injection leading to catastrophic breakdown has been used to study the dielectric properties of the buried oxide layer in silicon implanted with high‐energy oxygen ions. Current versus gate bias, current versus time, and capacitance versus gate bias were used to characterize, at various temperatures, MOS metal‐oxide‐semiconductor capacitors with areas in the 1×10−4–1×10−2 cm2 range fabricated with commercially available single‐ or triple‐implant separation by implanted oxygen silicon wafers. The data show that injected charge accumulates in the buried oxide at donorlike oxide traps ultimately leading to catastrophic breakdown. Both Poole–Frenkel and Fowler–Nordheim conduction, as well as impact‐ionization mechanisms, have been identified in the oxide. The charge and field to breakdown in the best buried oxides are, respectively, near 1 C cm−2 and 10 MV cm−1, similar to the thermally grown oxide parameters. Cumulative distributions of these parameters measured over a large number of capacitors show ...

Mechanism of defect formation in low-dose oxygen implanted silicon-on-insulator material

The defects and microstructure of low-dose (<0.7 × 1018 cm−2), oxygen-implanted silicon-on-insulator (SIMOX) material were investigated as a function of implant dose and annealing temperature by plan-view and cross-sectional transmission electron microscopy. The threading-dislocations in low-dose (0.2∼0.3×1018 cm−2), annealed SIMOX originate from unfaulting of long (∼10 μm), shallow (0.3 μm), extrinsic stacking faults generated during the ramping stage of annealing. As dose increases, the defect density is reduced and the structure of the buried oxide layer evolves dramatically. It was found that there is a dose window which gives a lower defect density and a continuous buried oxide with a reduced density of Si islands in the buried oxide.

Persistent photoconductivity in SIMOX film structures

Photoinduced transient spectroscopy (PITS) was used to measure the persistent photoconductive (PPC) response in n‐type separation by implanted oxygen (SIMOX) film resistors. A broadband, single‐shot, flashlamp‐pumped dye laser pulse was used to photoexcite interband electrons in the film, and the excess carrier population decay was measured at temperatures in the 60–220‐K range. The PPC signals exhibit nonexponential character and the conductivity transients are recorded as a function of temperature for variable periods up to 30 s. The photoconductive data are analyzed by using the Queisser and Theodorou potential barrier model, and a logarithmic time‐decay dependence is confirmed for the first time in SIMOX material. The hole‐trap density at the conductive‐film–buried‐silica interface is calculated to be in the high 1015 cm−3 to low 1016 cm−3 range. The sensitivity of PITS is demonstrated to be appropriate for characterization of the SIMOX interface structure and for material qualification.

Residual defects in SIMOX: threading dislocations and pipes

Some techniques are discussed for monitoring dislocations and stacking faults in SIMOX (separation by implantation of oxygen) films. Also, a different type of defect, a silicon pipe running through the buried oxide, has been observed. The origin of these defects and a technique for detecting them are described.<<ETX>>

An investigation of the two-dimensional shape of ion-implanted regions

The two‐dimensional shape of arsenic ion‐implanted regions in single‐crystal silicon was investigated both experimentally and theoretically. Experimentally, two techniques were shown to have the necessary submicron resolution: a junction etch process and a scanning electron microscope‐induced current collection method. A comparison of junction depths determined by the etch technique and the electron beam induced current technique with the depths calculated using several amorphous target codes was made. For the case of low temperature (600 °C) anneals, the etch technique agrees very well with the junction depths predicted by the amorphous target code due to Winterbon. The lateral junction locations obtained from the etch technique are in good agreement with the predictions of a two‐dimensional Monte Carlo code which indicates that the arsenic does not show any significant lateral scattering under mask edges. For the high temperature (1000 °C) anneals, the etch and electron beam induced current techniques a...