Surface proximity and boron concentration effects on end-of-range defect formation during nonmelt laser annealing

Abstract

The effects of surface proximity and B concentration on end-of-range defect formation during nonmelt laser annealing in preamorphized silicon have been studied. These effects were analyzed by observing the activation and diffusion of an ultrashallow B implant, using Hall effect and secondary ion mass spectrometry measurements. By adjusting the preamorphizing implant and laser annealing conditions, B deactivation and diffusion were minimized, resulting in a sheet resistance of ϳ600 ⍀ / sq with a 16 nm junction depth. This is attributed to a combination of enhanced dissolution of end-of-range defects and preferential formation of B-interstitial clusters due to the surface proximity and high B concentration, respectively.

Extended Defects Formation in Nanosecond Laser-Annealed Ion Implanted Silicon

“…In contrast, the much shorter duration time of excimer laser annealing (<200 ns) is comparable to that of some basic point-defect related phenomena, such as Si interstitial diffusion and clustering 11 , which makes the defect-formation mechanism itself questionable in this annealing regime. In addition, most of the existing studies of defect formation in laser annealed silicon have been carried out in preamorphised structures: (i) after non-melt anneals, conventional endof-range defects ({311} defects and {111} DLs) have been observed [12][13][14] ; (ii) in the case of melt laser annealing, the defects nature depends on the position of the melt front with respect to the amorphous/crystalline, a/c, interface (stacking faults are observed in the case of incomplete melting of the preamorphised layer, 15 defect-free crystalline silicon is found when melting goes beyond the a/c interface 16 ).…”

Source-drain Engineering for Channel-limited PMOS Device Performance: Advances in Understanding of Amorphization-Based Implant Techniques

“…The same study showed poorer results using preamorphization implants, although the comparison was somewhat approximate because the preamorphization energies used produced deeper amorphous layers than the B 18 H 22 implants. In order to make a direct comparison with the molecular implant results, we now revisit recently reported observations using preamorphization implants with a range of incident energies [4].…”

“…, to show all EOR dislocation loops that are present (Ref. [4]). In case (a), 10 keV Ge, a significant number of loops are present after laser anneal.…”

“…The impact that more stable EOR defects have on diffusion can be seen from boron atomic depth profiles, measured by SIMS [4], shown in Fig. 8.…”

“…9 which shows data on the time evolution of electrical activity, determined by sheet-Hall measurements [4,5] In the 5 keV and 10 keV cases, activation falls as interstitials from deep EOR defects flow back towards the surface, trapping into boron-interstitial clusters within the boron profile as outlined in Fig. 2c.…”