Characterization of an ultrashallow junction structure using angle resolved x-ray photoelectron spectroscopy and medium energy ion scattering

Abstract

The control of dose and energy (and therefore depth distribution) of ion implantation in n-channel MOSFET (NMOS) ultrashallow junctions is vital. Therefore there is a need to provide reliable metrology. Since the standard sheet resistance probing method, and the dynamic secondary ion mass spectroscopy method used to calibrate it both become more problematic for very shallow junctions, other techniques need to be evaluated. Angle resolved x-ray photoelectron spectroscopy (AR-XPS) is investigated here as an additional, nondestructive, laboratory-based tool to characterize NMOS junctions. The arsenic depth distribution and chemical bonding configuration are investigated for a set of p-type wafers implanted at 2keV with nominal doses from 1×1015to2×1015at.∕cm2. The results are compared to those using medium energy ion scattering (MEIS). It is demonstrated that XPS is a useful nondestructive tool for obtaining dopant chemical bonding state, qualitative elemental and chemical state depth information without modeling, and quantitative information on overlayer film thickness. Modeling the AR-XPS data and comparison to trial depth structures can lead to a more quantitative, but crude, depth profile. The combination of AR-XPS and MEIS was also able to explain why secondary ion mass spectroscopy profiling measures an approximately 2% increase for 1×1015at.∕cm2 in apparent dose on annealing the arsenic as-implanted wafer.

Electrical Resistance of AgTS–S(CH2)n−1CH3//Ga2O3/EGaIn Tunneling Junctions

“…Figure 3b shows Relative depth profiles (RDPs) provide a semiquantitative way of summarizing ARXPS data. 77 The relative depth (RD i ) of a chemical species i is calculated as RD i = log(I θ1 i /I θ2 i ), where I θ1 i and I θ2 i are the intensities of the XPS signals from the species i collected at angles θ1 and θ2 from the normal to the surface, and θ1 > θ2 (i.e., θ1 is more surface sensitive than θ2). (Compared to other approaches, RDPs avoid making assumptions about the structure of the surface, or about the lateral distribution of the species.)…”

Grazing incidence x-ray fluorescence and secondary ion mass spectrometry combined approach for the characterization of ultrashallow arsenic distribution in silicon

“…where AD is the apparent depth obtained converting the sputtering time to depth using the final crater depth and C was a factor determined by fitting. 10,11 Since the dopant atoms in ultrashallow junctions are mostly confined to the first few nanometers, alternative techniques such as angle-resolved x-ray photoelectron spectroscopy 12 and grazing incidence x-ray fluorescence ͑GIXRF͒, whose probing depths are around 10 nm, can be applied to evaluate the retained dose and possibly the depth distribution of the dopant. 13 In particular, in GIXRF the sampling depth can be varied by changing the x-ray beam incidence angle from zero up to a couple of times the critical angle for total reflection.…”