The annealing of semiconductors is of critical importance for successful electronic device fabrication. The present review surveys the new field of transient annealing and covers all timescales below those available with the conventional furnace. The work outlined includes the use of techniques which rely upon transient energy deposition in semiconductors from laser, electron beam, ion beam and other radiant sources. The many advances which have been achieved using these transient annealing methods in both fundamental and applied areas of physics are described.

http://iopscience.iop.org/article/10.1088/0034-4885/48/8/002/pdf

Transient annealing of semiconductors by laser, electron beam and radiant heating techniques

An isothermal processing system using a 2‐kW electron beam is described. Processing of areas up to 4×4 in. is achieved by rapidly scanning the beam in the multiple scan mode. An analysis of this method and some typical heating cycles for silicon wafers are presented. There is good agreement between theoretically predicted and experimentally measured temperatures. Additionally, closed‐loop operation is demonstrated where an optical pyrometer is used to control the electron beam current. This machine can either process whole wafers, or can sequentially treat a large number of small chips. This enables, for example, the rapid assessment of the annealing behavior of a particular implant by processing chips, cut from the same wafer, under varying conditions. Heating cycles of a fraction of a second to tens of seconds or more, which are not possible with furnaces, at temperatures up to 1000°C or greater have found many applications in semiconductor processing. Two important uses are described in this paper illu...

Electron beam system for rapid isothermal annealing of semiconductor materials and devices

(100) Si specimens implanted with a dose of 1015 As++ cm−2 at an ion energy of 760 keV contain a buried amorphous layer due to radiation damage which is annealed by irradiation with a scanned electron beam. The different stages of the solid-phase epitaxial regrowth and the residual damage are made visible by transmission electron microscopy of cross-sectional specimens. The regrowth rate of the interface of the amorphous zone facing the specimen surface is 50% higher than that of the interface facing the bulk. This difference is attributed to the dependence of the regrowth rate on the concentration gradient of diffusing point defects.



(100)-Si-Proben, die mit einer Dosis von 1015 As++ cm−2 bei einer Ionenenergie von 760 keV implantiert werden, enthalten eine vergrabene amorphe Schicht infolge von Strahlenschadigung, die durch Abrastern mit einem Elektronenstrahl ausgeheilt wurde. Die verschiedenen Stufen der epitaxialen Festkorperphasen-Rekristallisation und die zuruckbleibenden Gitterstorungen sind durch transmissions-elektronenmikroskopische Aufnahmen an Querschnittspraparaten sichtbar gemacht worden. Die Rekristallisationsgeschwindigkeit der oberflachenseitigen Grenzflache der amorphen Zone ist um 50% hoher als diejenige der dem Inneren zugewandten Grenzflache. Dieser Unterschied wird der Abhangigkeit der Rekristallisationsgeschwindigkeit von dem Konzentrationsgefalle der diffundierenden Punktdefekte zugeschrieben.

Kinetics of scanned electron beam annealing of high‐energy as ion implanted silicon

This paper describes the characterization of residual defects using transient capacitance spectroscopy for ion‐implanted Si annealed with a Q‐switched Nd‐glass laser. The deep‐level defect levels observed in this study were similar to those obtained in low‐fluence ion implanted samples. The spatial distributions of deep‐level defect concentrations were obtained for conditions using different anneal energy densities. From the difference of the distribution profiles, it is concluded that the greater the annealing laser energy densities, the lower the defect concentration near the junction.The reduction of the defect concentration is partly due to the inward movement of the junction. Thus the defects detected are those which lie further down in the tail of the defect distribution profile and have a lower concentration. Other reasons for the reduction of the defect concentration can be due to thermal annealing as heat propagates into the substrate during laser radiation. The reduction of the defect concentrat...

Defects in Q‐switched laser annealed silicon

The multiply scanned electron beam method has been applied to annealing selenium implanted gallium arsenide. The conditions necessary to give good electrical activation and mobility have been established for doses from 5×1012 to 1×1014 ions cm−2. Partial activation was achieved in uncapped samples for doses of 1×1013 cm−2 and greater. However, to achieve higher activation of these doses, and significant activation of low doses, encapsulation with Si3N4 was necessary. It is shown that rapid electron beam annealing lasting only a few seconds gave equivalent results to conventional furnace annealing methods.

Electron beam annealing of selenium‐implanted gallium arsenide

Silicon implanted with As+, P+, or B+ ions has been annealed by the multiple‐scan electron beam method and by use of pulsed radiation from a Q‐switched ruby laser. Electron microscope examination of specimen cross section gives direct comparison of the initial implantation damage with the structures produced by the different annealing methods. Sample electric conductivities after annealing are also compared. This work highlights the differences between the liquid‐ and solid‐phase annealing mechanisms of the pulsed‐laser and scanned‐electron‐beam methods, respectively.

A. G. Cullis

Papers

Comparative structural and electrical characterization of scanning-electron- and pulsed-laser-annealed silicon