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Nanosheet Field-Effect Transistors (FETs) are candidates to replace today’s finFETs as they offer both an enhanced electrostatic control and a reduced footprint. The processing of these devices involves the selective lateral etching, also called cavity etch, of the SiGe layers of a vertical Si/SiGe superlattice, to isolate the future vertically stacked Si channels. In this work, we evaluate the capabilities of various conventional Critical Dimension (CD) and alternative spectroscopic techniques for this challenging measurement of a buried CD. We conclude that Raman and energy-dispersive X-ray spectroscopies are very promising techniques for fast inline cavity depth measurements.

For patterned TiN/silicon oxide/low-k dielectric stack, fluorinated etch residues were detected on the TiN surface, the dielectric sidewall and bottom, regardless of the low-k material used in the stack. XPS results showed that they consisted of polymer-based (CFx) residues deposited on trench sidewall and bottom, and metal-based (TiFx) residues mainly deposited on top surface. In terms of post-etch residue removal, the efficiency of various wet clean solutions can be clearly distinguished for CFx, and TiFx using the same patterned porous low-k stack. These results also demonstrate that the removal of both TiFx and CFx residues generated during the plasma is possible in one step with optimized chemical and process.

A combination of wet chemistry and high-velocity solid CO2 aerosol pre-treatment was used to remove ion-implanted resist from patterned Si structures. The top resist surface is modified by heavy ion-implantation forming a crust ~100nm thick. The aerosol treatment, which is aimed at breaking and partially removing the crusted top layer of implanted resist, produces circular openings in this surface, with diameters on the order of tens to hundreds of micrometers. No resist is detected by either optical microscopy or localized SEM inspection, after immersion in hot SPM mixture, on aerosol-pre-treated wafer fragments. In contrast, resist residue is still observed on similarly pre-treated specimens, after immersion in either N-methyl pyrrolidone or Microstrip2001{trade mark, serif}, even under ultrasonic agitation. Overall, the aerosol pre-treatment is a key step in reducing the amount of resist residue, for both aqueous-based and solvent-based wet cleaning. Full-wafer defect-count results, post aerosol treatment, are reported for poly-Si line widths down to 40 nm.

The formation of shallow junctions in germanium substrates, compatible with deep submicron CMOS processing is discussed with respect to dopant diffusion and activation and damage removal. Examples will be discussed for B and Ga and for P and As, as typical p- and n-type dopants, respectively. While 1 to 60 s Rapid Thermal Annealing at temperatures in the range 400-650oC have been utilized, in most cases, no residual extended defects have been observed by RBS and TEM. It is shown that 100% activation of B can be achieved in combination with a Ge pre-amorphisation implant. Full activation of a P-implant can also be obtained for low-dose implantations, corresponding with immobile profiles. On the other hand, for a dose above the threshold for amorphisation, a concentration-enhanced diffusion of P occurs, while a lower percentage of activation is observed. At the same time, dose loss by P out-diffusion occurs, which can be limited by employing a SiO2 cap layer.

The density of hafnium oxide films grown by atomic layer deposition for high-κ gate dielectric applications was investigated for films with thickness in the nanometer range. The density, measured by combining the film thickness from transmission electron microscopy with the amount of hafnium deposited from Rutherford backscattering, decreased with decreasing film thickness. The dielectric constant of hafnium oxide remained constant with decreasing film thickness, however. The main reason for the decrease in the measured density seemed not to be a decrease in the inherent material density. Instead, the relative importance of interface roughness in the density measurement increased with decreasing film thickness.

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In order to reach the ITRS goals for future complementary metal-oxide semiconductor technologies there is a growing interest in using germanium as an alternative substrate material in view of its higher mobility. Different species and thermal budgets are presently being investigated in order to determine the most likely candidates for the required junction formation. A key issue is the accurate determination of the achievable electrical activation, i.e., the reliable measurement of the sheet resistance and electrical depth profile. In order to be applicable to Ge-based junctions, standard techniques such as the spreading resistance probe and scanning spreading resistance microscopy (SSRM) need to be reevaluated in terms of their performance and operational conditions. First, the significantly different behavior of germanium calibration curves (versus silicon) will be discussed. Next, the shape and characteristics of the probe imprints (Ge is softer than Si) and the differences in raw data behavior will be...

Solid phase epitaxial regrowth (SPER) is a promising method for junction formation of sub-65 nm complementary metal–oxide–semiconductor technology nodes. This is mainly due to a high dopant activation level, easy control over electrical junction depth, excellent abruptness, and limited boron diffusion. In the present research we investigate in detail the activation process and the chemical profile change after SPER junction activation with respect to the regrowth temperature. We also obtain the electrically active profiles. We find that the process window for SPER between T=620 °C and T=740 °C offers the best activation level and has a dopant profile similar to the as-implanted. While increasing the regrowth temperature, we observe the gradual increase of the transient enhanced diffusion effect and formation of B trapping centers in the end-of-range (EOR) region. At temperatures as high as T=800 °C and T=850 °C the dopant activation beyond the original a-Si layer is observed and the high metastable B acti...

The spreading resistance probe (SRP) tool is widely used for obtaining the electrically active dopant profile in silicon. In this work, the capabilities of SRP for thin metal film (Cu/Al/TaN) characterization are investigated. It is well known that quite large correction factors (∼500) are involved in sub-100 nm silicon SRP profiling to extract the underlying carrier depth profiles from the measured raw resistances. These large correction factors also allow, in principle, for the characterization of sub-100 nm metal layers, as their measured resistances will fall in the 1–100 ohm range. Structures consisting of Cu or Al metal layers, respectively, with different thicknesses (25–400 nm) on a Ta/TaN barrier layer (∼20 nm) on SiO2 have been characterized with SRP. For calibration, the characteristics of the probe imprints have been measured with atomic force microscopy. Present results indicate that for the thinnest Cu films, it is possible to obtain a resistivity depth profile in good agreement with availab...