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Molecular Fractal Surfaces Analysis by Spectroscopic Ellipsometry. F. Ferrieu 1 J.P. Piel 2 and J.L.Stehlé 2 A.Danel 3 ICSE4 June 11 th , 2007. 1 STMicroelectronics , 850, rue Jean Monnet, F38926 CROLLES Cédex France. 2 SOPRA-SA 26, rue Pierre Joigneaux, 92270 BOIS-COLOMBES France
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Molecular Fractal Surfaces Analysis by Spectroscopic Ellipsometry F. Ferrieu1 J.P. Piel2and J.L.Stehlé2 A.Danel 3 ICSE4 June 11th, 2007 1STMicroelectronics, 850, rue Jean Monnet, F38926 CROLLES Cédex France. 2SOPRA-SA26, rue Pierre Joigneaux, 92270 BOIS-COLOMBES France 3 CEA/LETI Minatec 17 rue des Martyrs 38054 GRENOBLE cedex 9 France.
Molecular Fractal Surfaces Analysis by Spectroscopic Ellipsometry • Introduction • Adsorption Process Interactives Forces Fractal Surfaces • Exp Set Up and data processing • Some examples • Conclusions
SURFACE NATURE • Extreme sensitivity of the Ellipsometry Technique • Archer, R.M.Pashley Jour.Colloid and Interface 71,3,491(1977) • SURFACE SPECIFITY ROUGHNESS LATERAL CORRELATION Fractal Dimension
SURFACE ANALYSIS Fractal Dimension CORRELATION LENGTH
SURFACE ANALYSIS • Basic Surface Adsorption Theories • BET (1938) Plane surface no particules interactions
Adsorption Force Van Der Waals Dipole-Dipole short range London long range L-6 interaction energy See,e.g., R.French J.Am.Ceram.Soc.83,9,2117(2000)
Fractal Theory developments • B. MandeBrot ”The Fractal Geometry of Nature”, edited by Freeman San Francisco,1982). • Application turned to Halsey Modified (FHH) N number of time the use of metric R is accomplished to get the area (length (1) or Volume (3)) of a self affine fractal object with dimension D Metric R is the molecule size • Nm monolayer coverage • film thickness at pressure p • N coverage at pressure p Extension to BET-Fractal formalism:
Extension to BET-Fractal formalism: • Active surface Area Isotherm determination : Vm monolayer coverage Cm monolayer capacity a=3-D fractal surface dimension Formalism (ASA)
EP Cell Polarized Light Experimental set up Ellipsometry Porosimetry EP
EP SOPRA set up Optical Fiber Light Source CCD Spectrometer Polarizer Analyzer Z Compensator CCD Ellipsometer Door Window Baratron Gauges Wafer < 10 Torrs < 760 Torrs Chuck Measuring System Vacuum Chamber SW1 Heated box V9 Fab Facilities Throttle Valve Pressure Valve V5 Baratron Gauge < 100 T Heater N2 Line V6 N2 Line V10 Filter V1 Purge System V11 Turbo Pump V3 V4 V2 Valve driven by timer Dry Pump Solvent Vessels Over pressure Security V7 V8 SW5 SW4 SW3 Vapor Generating System Vacuum System
water H2O Adsorption technique EPA @Sopra Patented
Non Linear Fit Program C parameter low partial pressure region (or low R.H.) Vm offset t(p) dominated by a ln(1-p)whne r.H.~>1
High k HfO2 surfaces 3-D character Volume>surface adsorption Open microporosity Not yet verified by other techniques Hydrophilic contaminated surface
Conclusions: Molecular Surface Fractal Analysis (MFSA), • High sensitivity and high speed of today’s SE instruments • A new potential development orientation for surface, modification during a process,( etching, plasma, epitaxial films,..). • Understanding of fundamental adsorption mechanism • Surface molecular orientation by polarimetry • The basic system remains more versatile adjusting molecular metrics but need low pressure, temperature controlled with fast in situ SE ellipsometer. • H2O, refined EPA version is an easy method in the case of many inert hydrophilic surfaces of the nanotechnology