Defect engineering involves manipulating the type, concentration, spatial distribution, or mobility of defects within a crystalline solid. Defect engineering in semiconductors has become much more sophisticated in recent years, driven by the need to control material properties at small length scales. The present article describes recent trends in defect engineering across several nano-oriented applications, beginning with Si-based integrated circuits and extending into non-Si microelectronics and especially into oxide semiconductors for sensors and photocatalysis. Special focus fixes upon physical mechanisms that have been little exploited up to now, but show significant promise as new means for controlling defect behavior, including low-energy ion bombardment, surface chemistry, and photostimulation. Systems-based methods for parameter estimation offer considerable promise for helping to understand the complex diffusion and reaction networks that characterize defect behavior in most prospective applications.

Trends in semiconductor defect engineering at the nanoscale

The present invention provides methods for controlling defects in materials, including point defects, such as interstitials and vacancies, and extended defects, including dislocations and clusters. Defect control provided by the present invention allows for fabrication and processing of materials and/or structures having a selected abundance, spatial distribution and/or concentration depth profile of one or more types of defects in a material, such as vacancies and/or interstitials in a crystalline material. Methods of the invention are useful for processing materials by controlling defects to access beneficial physical, optical, chemical and/or electronic properties.

Defect engineering in metal oxides via surfaces

In this work we present results on sub-melt Excimer laser annealing in order to obtain difussionless activation of Boron for the creation of ultra shallow P-MOS devices. For the fulfillment of the strict requirements imposed by the ITRS roadmap for the 32 nm node we have implemented two emerging techniques: non-melt laser annealing and BF 3 Plasma Doping implantation (PLAD). By using PLAD, we were able to create ultra shallow and abrupt as implanted profiles. On the other hand, by performing laser annealing on the samples in the sub-melt regime, we can achieve high levels of electrical activation, while practically eliminating Boron diffusion, due to its capability to deliver low thermal budget in the sub-microsecond time scale. An Excimer KrF laser ( λ  = 248 nm and pulse duration 38 ns) has been used. The post annealing characterization of the samples included SIMS and Van Der Pauw Sheet resistance measurements. SIMS data indicate almost difussionless dopant behavior with R s values at 680 Ω/sq. We have concluded our analysis with the examination of the morphological characteristics both of the surface of the sample using Atomic Force Microscopy (AFM) and the evolution of the recrystallization of the amorphized layers and the removal of the defects by means of cross-section Transmission Electron Microscopy.

Non-melt laser annealing of Plasma Implanted Boron for ultra shallow junctions in Silicon

Millisecond annealing techniques with flash lamps or lasers have become increasingly common for activating dopants and eliminating implantation-induced damage after ion implantation for transistor junction formation in silicon. Empirical data show that such techniques confer significant benefits, but key physical mechanisms underlying these benefits are not well understood. The present work employs numerical simulation and analytical modeling to show that for boron, millisecond annealing reduces unwanted dopant spreading by greatly reducing the time for diffusion, which more than compensates for an increased concentration of Si interstitials that promote dopant spreading. Millisecond annealing also favorably alters the relative balance of boron interstitial sequestration by the crystal lattice vs interstitial clusters, which leads to improved electrical activation at depths just short of the junction.

Mechanistic benefits of millisecond annealing for diffusion and activation of boron in silicon

Because of the short penetration depth of ultraviolet (UV) in semiconductor, the realization of UV sensors requires the reduction of the junction thickness. Excimer laser annealing (ELA) is a new annealing technical allowing to achieve a thin layer ( The small size of the laser beam requires a scanning procedure for processing large surfaces. That could generate non-homogeneities resulting in defect growth. In order to investigate these phenomena, we developed a Light Beam Induced Current (LBIC) measurement set-up. LBIC analyses consist in the measurement of the photocurrent generated by a localized irradiation of the sample. The presence of defects in the irradiated zone leads to a local decrease of the photo-current. Moreover, thanks to different probe beams with wavelengths ranging from 193 nm to 800 nm, we can control the depth of photo-carriers generation. Thus, we are able to perform a 3D-localization of the defects which helps in understanding their origins. We have developed and validated this detection method of defects generated in the ultra-thin junctions, down to thirty nanometers, with a spatial resolution of ten micrometers at the surface of the sample. First experimental results demonstrate that most of the defects are localized at the edge of the irradiated zone within the first ten nanometers from the surface.

LBIC measurement optimization to detect laser annealing induced defects in Si

This work combines plasma doping implantation (PLAD) with laser annealing using excimer laser, for the formation of ultra-shallow junctions. For that purpose, high dose BF3 was implanted in n-type silicon wafers using PLAD. The as implanted material was investigated by high resolution TEM, measured by SIMS and simulated by Monte-Carlo codes. Subsequently, the samples were annealed using a KrF laser source at 248 nm with a pulse duration 20 ns and different fluence values. Laser annealing completely recrystallizes the amorphous layer as monitored by TEM measurements, fully activates the dopants achieving low sheet resistance values as shown by Van der Pauw measurements and results in box-shaped dopant profiles with movement less than 10 nm at the junction depth as measured using SIMS.

A. Halimaoui

Papers

Laser annealing of plasma implanted boron for ultra-shallow junctions in Silicon