HD STRAIN 3D strain metrology for electronic devices Journées Nationales en Nanosciences et Nanotechnologies 2012 CEMES Toulouse LETI Grenoble Crolles Grenoble Develop Dark-Field Electron Holography (HoloDark) for Strain Metrology in Devices • Methodology: 2D → 3D measurements • Instrumentation: brighter electron sources, in-situ experiments • Characterisation: model → industrial specimens A Conventional holography incident beam incident beam transmitted beam holographic fringes Si Si 1-x Ge x source drain gate MOSFET Transistor Strained Si Nitride layer SiGe SiGe -3% 3% ε xx 200 nm s-Si Si 1-x Ge x Dark-Field Electron Holography M J Hÿtch, F Houdellier, F Hüe, E Snoeck, Nature 453, 1086 (2008) Strained Silicon • Strained silicon channel • Strain engineering methods include embedded sources and strain layers; technology which is industrial standard • Straining silicon increases carrier mobility (electrons or holes) Strain Mapping need for measurement reliable and robust technique for strain measurements Contact: Martin Hÿtch [email protected] Tomography International Patent Application: PCT N° PCT/FR2008/001302 (CNRS) F Hüe, M J Hÿtch, F Houdellier, H Bender, A Claverie, APL 95, 073103 (2009) Finite Element Model • New technique interferes diffracted beams from unstrained (A) and strained (B) regions • Advantages include: μm-field of view, high spatial resolution and high precision M J Hÿtch et al. Physica Status Solidi A 208, 580 (2011) HoloDark 1.0 software (HREM Research Inc.) by M J Hÿtch, C Gatel, K Ishizuka HD HB α=40° 0 50 100 150 200 -2 0 2 4 6 8 10 12 14 16 Y X ( nm ) ampl phase 0 20 40 60 80 100 120 140 160 180 200 0 2 4 6 8 10 12 14 16 amplitude X ( nm ) Exp Simu Experiment α=34° M J Hÿtch, F Houdellier, F Hüe, E Snoeck, Ultramicroscopy 111 1328-1337 (2011) Holographic fringes Incident beam Diffracted beam B A reference Diffracted beam A B strained Biprism C G φ φ + C φ G φ α=2° α=15° α=40.5° Dark field hologram Phase image Amplitude image In situ TEM measurements and finite element modelling Al Si SiO 2 Diamond tip Bulk Si Indentation mark in the silica Slip-traces + stereographic projection map -> slip plane (111) Cross-slip event -> Burgers vector b=[01-1] Resolved shear stress Applied force T=[103] -> Schmid factor Shear stress τ = μ b /R = 200 MPa Brighter electron source F Houdellier and M Monthioux, French Patent Application, FR 10 03696, 2010 (CNRS) F Houdellier, A Masseboeuf, M Monthioux, M J Hÿtch, Carbon 50 (2012) Development of a New Cold Field-Emission Gun for Electron Holography. Carbon tip W[310] tip W[310] tip Carbon tip Emission current = 8 µA Exposure = 1 s C 2 aperture = 50 µm CCnT CCnT ref. meas. biprism d +γ → work function φ I = A 1.5×10 −6 φ E loc 2 exp 10.4 φ # $ % % & ' ( ( exp − 6.44 ×10 9 φ 1.5 d γV # $ % & ' ( E loc = γ E 0 = −γ V d γ = 21.5 φ = 4.8± 0.3 eV d= 680 nm Au anode Etched W wire Carbon cone nanotip V i 10 μm d L de Knoop, S Reboh, M Legros E Javon, C Gatel, A Lubk, M J Hÿtch L de Knoop, F Houdellier, C Gatel, A Masseboeuf, M Monthioux, M J Hÿtch Anode 80 V CCnT Phase ϕ = C E V dl beampath ∫ γ = Eloc E0 = 2.58 0.12 = 21.5 FowlerNordheim equaCon: Anode 80 V Cross slip event Al Si SiO 2 Bulk Si 0 GPa 2 GPa S = cos T, b ( ) ⋅ cos T, (111) ( ) = 0.48 σ = τ / S = 400 MPa Slip trace R External stress with 150 μN applied force -> 2-300 MPa in Al layer Simulation 0 20 40 60 80 100 120 140 160 180 200 220 -6 -4 -2 0 2 4 6 8 10 12 14 Amplitude X ( nm ) HB HD a) TEM micrograph b) Experimental strain map c) FEM of strain a) b) c) 01/01/2009 -> 30/09/2013 Anode 80 V