Lin Chenglu

Infrared absorption and reflection spectroscopic studies of SOI structures formed by oxygen or nitrogen implantation

Abstract Silicon on insulator (SOI) structures have been formed by nitrogen or oxygen implantation with a dose of 1.8 × 10 18 ions/cm 2 at 190–200 keV. Infrared (IR) absorption and reflection spectra in the wavenumber range 400–5000 cm −1 were measured for SOI structures after various thermal anneal treatments. Localized vibrational modes and interference fringes were observed in the IR spectra. By IR absorption and thermodynamic analysis, it was found that crystalline α-Si 3 N 4 was formed in the buried nitride layer of SOI structure after annealing at 1200°C for 2 h. However, the buried layer formed by oxygen implantation was still amorphous SiO 2 after annealing at 1300°C for 5 h. By detailed theoretical analysis and computer simulation of the IR reflection interference spectra, refractive index profiles of SOI structures were obtained.

SOI STRUCTURE FORMED BY 95 KEV N2+ AND N+ IMPLANTATION AND EPITAXIAL-GROWTH

Abstract N-type 100 Si wafers were implanted with 95 keV, (0.1–1) × 1018 cm−2 N2+ and N+ and a beam current of 6 mA by using an ion implanter without mass analysis. The wafers were maintained at 500°C during implantation. After implantation the samples were annealed at 1200° C for 2 h and underwent vapor-phase epitaxial growth. The experimental results showed that the thicknesses of the top silicon layer with a minimum channeling yield of 5% are 0.3–1 μm and the thicknesses of buried Si3N4 layer are 170–200 nm. The buried silicon nitride layer consists of polycrystalline α-Si3N4 and nitrogen-rich nitride. The Si-Si3N4 interface is extremely abrupt, and the spreading resistance depth distribution is uniform in the top silicon layer. The results indicate that this method is an effective technology for forming cheap SOI material.

Near-surface damage created in silicon by BF2+ implantation

Abstract The near-surface damage in silicon induced by the bombardment of 147 keV BF 2 + has been investigated by 2 MeV He + Rutherford-backscattering spectrometry. The implantation was carried out at room temperature with the ion doses ranging from ~ 10 13 to ~ 10 16 cm −2 . The radiation damage was compared with corresponding B + and F + atomic-ion implantation. A damage enhancement at the surface region of the silicon implanted with BF 2 + has been observed and it is attributed to the multiple-collision effect between molecular ions and host atoms.

A Study of Damage in Silicon Created By and P+ Implantation

The damage and annealing behavior of Si implanted at room temperature by and P + at different energies (5-600KeV) and intermediate dose (∼10 14 /cm 2 ) has been investigated. Experimental results show that the damage created by implantation is always greater than that of P + implantation. The ratio of total displaced atoms of the target cuased by molecular and atomic implantation, N D (mol)d/N D (atom) reached a maximal value at 100KeV ( ) and 50KeV (P + ) after rapid thermal annealing, the carrier concentration profiles measured by spreading resistance measurements are also different for the and P + implanted samples. We attribute essentially this phenomenon to the displacement spike, but the multiple collision effect and the interaction between two molecular fragments should be considered while the incident energy is high.

Dopant redistribution of As-implanted SOI films during rapid thermal annealing

Abstract Cw Ar+ laser recrystallized SOI films were implanted with As ions at 100 keV with doses of 1 × 1015−1 × 1016 cm−2 and then rapid thermal annealed with a rf graphite heater. Surface loss of As can be prevented by using N2 as protecting atmosphere. The diffusion behavior of dopants in SOI films has been investigated by RBS and SIMS in addition to spreading resistance measurements. For some annealing conditions double peaks have been observed in As atom concentration and carrier concentration profiles. It was supposed that the appearance of double peaks was caused by two different diffusion mechanisms — low diffusivity in the bulk of the grains and the higher diffusivity at grain boundaries.

Laser-Initiated Aluminothermic Reaction Applied to Preparing Mo-Si Film on Silicon Substrates

Mo-Si films on silicon substrates has been prepared by the CO 2 laser-initiated aluminothermic reaction. The features of these films have been characterized by RBS, AES, etc. The formation mechanism is discussed.

SYNTHESIS OF BETA-FESI2 FILM BY REACTIVE DEPOSITION - SOLID-PHASE EPITAXY

Reactive deposition—solid phase epitaxy has been developed for the epitaxial growth of thick β-FeSi2 film. Compared with the solid phase epitaxy, the crystal quality was improved. The orientation relationship mainly depends on the depositing condition. Observation by transmission electron microscope revealed the polycrystalline nature and the mean crystallite size was about 200 nm.

ANALYSIS OF ELECTRICAL-PROPERTIES OF BURIED NITRIDE FORMED BY HIGH-DOSE N+ IMPLANTATION

N-type 〈100〉 crystalline silicon wafers were implanted by N+ at 170 keV with doses ranging from (0.5–2.2) × 1018/cm2. All these implanted wafers were annealed at 1200°C for 2 h in dry-N2 ambient. Infrared (IR) transmission spectroscopic measurements showed that a buried α-Si3N4 layer was formed for those wafers in which the dose of implanted N+ was higher than 1 × 1018/cm2. B+, Si+ and Ar+ were implanted into these wafers to amorphize the buried α-Si3N4 in order to improve its insulating properties. IR measurements indicated that Si+ and Ar+ implantations can amorphize the buried α-Si3N4. Though the deposited energy density of B+ was higher than that of Si+ and Ar+, buried α-Si3N4 cannot be amorphized by B+ implantation. These wafers were annealed at 900 and 1150°C for 45 min. Amorphized nitride recrystallized to form α-Si3N4 after annealing at 1150°C. Ohmic contacts were fabricated at front and back sides for all wafers by As+ implantation and aluminium evaporation. I–V characteristics were measured and the effect of B+, Si+, and Ar+ implantations on insulating properties of the buried insulator was studied for all samples.

The effects of epitaxy and oxidation on the properties of SIMNI and SIMOX materials

Abstract SIMNI and SIMOX samples were subjected to burial by epitaxial growth of Si (1200°C), oxidation (900–1180°C, in O 2 or H 2 /O 2 ) and baking (1200° C, in H 2 ) to investigate in the changes in the properties of their surface and buried layers. The results of RBS/C and ASR pointed out that the minimum channelling yield of the top silicon layer of SIMNI decreased from 10% before epitaxy to 3.4% after epitaxy, while no properties of the SIMNI structure either in the remaining Si top layer or in the buried layer were changed during oxidation. The SIMOX structure without enough annealing would become damaged as a result of baking in H 2 at high temperature.

A STUDY OF MOLECULAR ARSENIC ION-IMPLANTATION IN SILICON

Abstract The radiation damage and annealing behavior of 〈100〉 Si implanted at room temperature by As+2 and As+ at equivalent energies are compared. It is found that the radiation damage created by As+2 implantation is greater than that created by As+ implantation. Shallow doped layers in silicon have been formed by As+2 implantation with low energies from 10 to 30 keV and doses from 5 × 1013 to 5 × 1015/cm2. Rapid thermal annealing is used to control the redistribution of implanted dopant. The results indicate that abrupt n+ -p junctions are shallow as 700–1500 A can be obtained by using As+2 implantation in combination with rapid thermal annealing.