Dopant characterization in self-regulatory plasma doped fin field-effect transistors by atom probe tomography

Abstract

Fin field-effect transistors are promising next-generation electronic devices, and the identification of dopant positions is important for their accurate characterization. We report atom probe tomography (APT) of silicon fin structures prepared by a recently developed self-regulatory plasma doping (SRPD) technique. Trenches between fin-arrays were filled using a low-energy focused ion beam to directly deposit silicon, which allowed the analysis of dopant distribution by APT near the surface of an actual fin transistor exposed to air. We directly demonstrate that SRPD can achieve a boron concentration above 1 × 1020 atoms/cm3 at the fin sidewall.

Elemental Distribution in Multilayer Systems by Laser-Assisted Atom Probe Tomography with Various Analysis Directions

“…The evaporation fields for B + , Ta +++ , Ru ++ , Co ++ , Ni ++ , Fe ++ , and Si ++ , which are the main charge states detected, are 64, 44, 41, 37, 36, 33, and 33 V/nm, respectively (Tsong, 1978; Miller, 2000). Thus, B, Ru, and Ta can be classified as high-evaporation-field elements, and the large difference in the critical evaporation field near the interface between adjoining layers gives rise to a deviation from the actual atom positions.…”

“…In particular, for the case of multiphase materials such as multilayer structures or nanocomposites, well-known artifacts due to differences in the critical evaporation field values for each layer during measurements are considered to have a significant impact on the spatial distribution of elements (Brandon, 1964). Larson et al (2011 c ) investigated APT accuracy and spatial resolution for multilayer thin films containing materials with low evaporation fields (Tsong, 1978; Miller, 2000), using analysis directions parallel and anti-parallel to the film growth direction. In practical applications of APT, it must be assumed that the subject materials may have a wide range of evaporation fields.…”

Atomic-scale characterization of germanium isotopic multilayers by atom probe tomography

“…For Si, APT analysis has been proven useful for obtaining dopant distribution and interface structures in modern electronic device structures. [13][14][15][16] Our recent APT characterization of Si isotopic multilayers showed very high spatial resolution, 0.4 nm/decade, at interfaces of 28 Si/ 30 Si heterostructures. 18 In order to evaluate the interfacial sharpness at each specific interface, the proximity histogram composition 28 (proxigram: a profile of local atomic concentrations vs. proximity to an interface) is employed for this assessment.…”

“…Laser-assisted APT has been adopted originally for practical metrology [9][10][11][12] and employed subsequently for threedimensional (3D) elemental mapping of modern electronic device structures [13][14][15][16] and quantitative evaluation of the interface sharpness of layer structures [17][18][19][20][21][22][23][24][25] with the order of atomicscale resolution. The unsurpassed spatial and isotopic resolutions of APT have been proven already in characterization of 28 Si/ 30 Si interfaces in Si isotopic heterostructures.…”

Three-Dimensional Nanoscale Mapping of State-of-the-Art Field-Effect Transistors (FinFETs)

“…Further studies on Si-germanium (Ge) epitaxial layers (Kelly et al, 2007) were followed by reports on planar high-κ dielectrics analyzed using both secondary-ion mass spectrometry and APT to show the reliability of APT (Ulfig et al, 2007;Larson et al, 2008). Subsequent studies on distribution of boron and phosphorus dopants during processing and on boron distribution during ion implantation were also reported (Takamizawa et al, 2012;Han et al, 2015). Individual planar metal-oxide semiconductor field-effect transistor devices have also been analyzed by Inoue et al (2009) and by Larson et al (2011).…”