Advanced Thermal Processing of Ultrashallow Implanted Junctions Using Flash Lamp Annealing

Abstract

The use of flash lamp annealing for ultrashallow junction formation in silicon has been described. Low energy boron and arsenic implants have been heat-treated in this way using peak temperatures in the range of 1100 to 1300°C and effective anneal times of 20 and 3 ms. Secondary ion mass spectrometry and four-point probe measurements have been undertaken to determine the junction depth and the sheet resistance, respectively. Optimum processing conditions have been identified, under which one can obtain combinations of junction depth and sheet resistance values that meet the 90 nm technology node requirements and beyond.Source/drain junction depths need to be reduced in line with the continuing scaling down of deep submicrometer devices in silicon. Currently, the technique of choice for producing ultrashallow junctions ͑USJs͒ that meet the specifications of the sub-90 nm node relies on the use of ultralow energy boron ion implantation followed by extremely short time thermal annealing. 1-3 The key structural parameters of a USJ are the sheet resistance R s and junction depth X j . According to the International Technology Roadmap for Semiconductors (ITRS) 2003 4 the realization of the 90 nm node, whose year of production is 2004, calls for R s ഛ 663 ⍀/ᮀ and X j ഛ 20.4 nm. The respective values for the 65 nm node, which is scheduled for the year 2006 are R s ഛ 884 ⍀/ᮀ and X j ഛ 13.8 nm.Thermal annealing techniques such as rapid thermal processing ͑RTP͒ and, more recently, spike RTP 1-3,5,6 have been adequate to control the processing of mainstream devices. These annealing methods, however, will soon become unsuitable for the USJs required in the near future. The reason is that the effective anneal times 7 used are still relatively long, being in the order of 1 s or more. The fabrication of USJs necessitates both very high annealling temperatures for achieving high electrical activation, and extremely short times of heat-treatment to minimize the effect of dopant transient enhanced diffusion ͑TED͒ 8 responsible for the undesirable junction broadening. The attempts to meet these two competing requirements have led to great interest in the development of alternative ultrafast heat-treatment methods, of which laser thermal processing ͑LTP͒ 9 and flash-assisted RTP ͑fRTP™͒ 10,11 are presently among the most promising ones.The common feature of all ultrafast thermal annealing processes is the use of a small thermal budget involving a high peak temperature, T max , coupled with a very short effective time of the anneal cycle and very high ramp-up/cool-down rates. LTP has some inherent problems associated with dopant deactivation and process integration. In fRTP™, the device structure is exposed to a short duration pulse or flash ͑on the order of milliseconds͒ of intense light produced by an arc lamp.We have developed and tested successfully an alternative version of ultrarapid thermal processing based on the use of a xenon flash lamp system, hereafter referred to as the flash lamp annealing ͑FLA͒ technique. Results of a p...

Suppressing the cellular breakdown in silicon supersaturated with titanium

“…The implanted layers were annealed by PLA and flash lamp annealing (FLA). Different from PLA, FLA in millisecond range can render the sample just slightly below the melting temperature leading to solid-phase epitaxy 21 . Our results indicate that Ti-implanted Si with a concentration above the equilibrium solid solubility limit can be recrystallized by both PLA and FLA.…”

Flash-Enhanced Atomic Layer Deposition: Basics, Opportunities, Review, and Principal Studies on the Flash-Enhanced Growth of Thin Films

“…[34][35][36][37][38] Consequently, FLA is a suitable technology to power high temperature processes even on temperature sensitive substrates. 34 Examples for the application of FLA are the activation of dopants and the defect annealing after ion implantation to form ultra-shallow junctions, 37,38 the crystallization of amorphous silicon in order to produce crystalline silicon on various substrates, 36,[39][40][41] the thermal treatment of high-k dielectrics for memory and transistor applications 42,43 and of transparent conductive oxide films for solar cell applications, 34 the sintering of particles 44 as well as ink-jet printed films, 45 and the deposition of thin films. [22][23][24][25][26][27][28][29] The latter use of FLA is the object of flash-enhanced ALD, which we describe in the following also abbreviated as FEALD.…”

Chemical ordering of FePt films using millisecond flash-lamp annealing

“…Further details of the flash-annealing setup are described elsewhere. [17][18][19] The structural properties of the samples were investigated by x-ray diffraction using beamline G3 of HASYLAB at DESY (wavelength k ¼ 1.54185 Å ) and their surface morphology was analyzed by atomic force microscopy (AFM). The integral magnetic characterization was performed using superconducting quantum interference device (SQUID) magnetometry with magnetic fields up to 70 kOe.…”

“…16 Flash-lamp annealing is another millisecond annealing process capable to heat thin films to temperatures above 1300 C. 17,18 and the prospects of this method for advanced semiconductor processing have recently been demonstrated. [18][19][20] In the present study, flash-lamp annealing with 20 ms light pulses was employed to process 20-nm-thick Fe x Pt 100Àx films (with x ¼ 42 À 60) sputter deposited at room temperature. The determination of the magnetic and structural properties with respect to chemical composition and annealing temperature gives further insight into the relevant parameters of the ordering transformation in the millisecond time regime.…”