MC Implant 1D/2D Monte Carlo Implantation Simulator Seamlessly Integrated into ATHENA’s SSuprem4
Summary � � MC Implant is an advanced 2-D ion-implantation physics based simulator for modeling of ion stopping and implant ranges in amorphous and crystalline media � � Comparisons to measured data have shown that MC Implant is still accurate and predictive even below 1keV � � With the ATHENA framework, MC Implant provides seamless bi- directional integration with SSuprem4 and Flash simulators allowing modeling of the implantation process for all available impurity/target material combinations and for any arbitrary geometry - 2 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Key Benefits � � Easy to use, self writing (menu driven) input files � � Predictive and experimentally verified results � � Fully integrated into Silvaco’s industry leading visualization tool � � Fully inter-active run time environment � � History file creation at every step allows real time modifications to input files � � Continuous, in house, customer driven development � � Fully integrated into Silvaco’s process simulation tool, SSuprem4 in ATHENA - 3 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Applications � � Process optimization for performance enhancement � � Analysis of material/topology effects on implant profile � � Implant damage and subsequent TED investigations � � Failure analysis � � Process robustness, manufacturability and yield analysis � � Investigation of mask (cost) reduction viability � � Novel devices � � Patent proposals and legal defense thereof - 4 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Usage - When to use a Monte-Carlo Simulator � � Unusual surface topology - eg shadowing effects � � Investigation of unusual phenomenon � � Implantation energy extremes - low or high � � When beam divergence is important - highly channeled � � Investigation of dominant channeling directions � � When amorphization effects are important � � Multi-layer material structures � � Whenever accuracy is more important than simulation time - 5 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Contents � � Topology effects - shadows, reflections and re-implantation � � Non intuitive phenomenon � � Calibration - how good is Silvaco’s simulator? � � 3D simulations � � Damage profiles and amorphization � � Increasing the simulation speed � � Some basic physics � � Concluding - 6 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Topology - Shadowing, Reflection & Re-implantation � � 10keV, 1e14/cm2 Boron implanted at 7 degrees � � Shows shadowing � � Ions initially reflected from the right hand side wall are re-implanted into the left hand wall. � � Shows expected increase in re-implanted dose with depth � � Implanted dose is reduced for high implant angles on the trench wall (CosØ effect) - 7 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Topology - Shadowing, Reflection & Re-implantation � � The same implant using ATHENA’s SIMS verified look-up tables (SSuprem4) � � Correctly shows shadowing and CosØ effect in right hand trench wall � � However, reflection and re- implantation effects are absent from the look-up table approach � � Monte-Carlo required for correct simulation of dopant distribution in this case - 8 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples � � Increasing surface screen oxide thickness increases ion channeling - why ? � � Monte Carlo Simulation provides the answer - The dominant channeling direction is not vertical. The thicker oxide increases the probability of ion scattering in this preferred “off-axis” direction - 9 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples � � Crystalline structure of silicon in various crystal directions � � Note the more open structure in the preferred channeling <011> direction giving rise to the effect on the previous slide - 10 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples � � An implanted ion’s eye view when channeling � � Simply a beautiful graphic showing how ions become channeled for certain crystal directions In 1962 ion channeling was discovered on a computer at ORNL. Reference: http://www.ornl.gov/ORNLReview/v34_2_01/fermi.htm - 11 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples � � Significant lateral spread under the gate � � Lateral spread in crystalline materials is much higher than in amorphous materials and is due to ion channeling in <011>, <110> and equivalent crystallographic directions � � The implant direction is <001> but because of dechanneling, ions enter the other planes � � This ion redirection is increased in the presence of oxide layers and with high dose implants � � The resultant lateral spread will affect device performance target such as puchthrough voltage - 12 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples � � Implantation of two similar mass ions, aluminum and phosphorus, results in greatly differing ion channeling depths by a factor of 3 - Why ? Reference: R.G.Wilson, J.Appl.Phys., Vol.60, pp2797-2805, 1986 Random and (110) channeled atom depth distributions for Al and P implanted into crystalline Si at 200 keV and 3 x 10 13 cm -2 - 13 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Unusual Effects - 2 Counter Intuitive Examples Electronic stopping for low energies � � Answer:- The electronic stopping cross section for the two ions in the <110> direction is greatly different � � The graphic shows Stereographic and schematic view of the (100) channel in silicon. electronic stopping in the <110> direction for ions of various atomic number � � Al = 13 P = 15 Reference: Ivan Chakarov “Atomic and Ion Collisions in The Zi-depence of the electronic cross-section Solids” Ed. R.Smith, Cambridge University (v = 1.5 x 108 cms-1 for the ){110} direction in Press, 1997 crystalline silion. Experimental points are from Eisen (1968. - 14 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Calibration - Measured versus Simulated Data � � Very low energy � � 0.5keV Boron - 1e12/cm2 � � 1keV Arsenic - 1e12/cm3 � � Both zero degree tilt - 15 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Calibration - Measured versus Simulated Data (con’t) � � Low energy � � 2 keV Boron - 1e12/cm2 � � Left - Zero Tilt � � Right - 7 Tilt, 45 Rotation - 16 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Calibration - Measured versus Simulated Data (con’t) � � Low energy � � 2 keV Arsenic - 1e12/cm 2 � � Left - Zero Tilt � � Right - 7 Tilt, 45 Rotation - 17 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Calibration - Measured versus Simulated Data (con’t) � � Medium energy � � 15 keV Boron - 1e13/cm 2 � � 80 keV Boron - 1e13/cm 2 � � Both - 7 Tilt, 30 Rotation - 18 - MC Implant 1D/2D Monte Carlo Implantation Simulator
The Monte-Carlo Simulator is Actually 3D � � Boron concentration contributions from various channeling angles MC Implant 1D/2D Monte Carlo Implantation Simulator - 19 -
The Monte-Carlo Simulator is Actually 3D (con’t) � � The same channeling contributions viewed from the surface - 20 - MC Implant 1D/2D Monte Carlo Implantation Simulator
The Monte-Carlo Simulator is Actually 3D (con’t) � � 3D boron point implant simulation integrated into 2D � � Also compared to other work fundamental atomistic calculations G.Hobler, G.Betz (Inst. F.Allg.Physik, TU Wien) - 21 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Damage Profiles and Amorphization - Dose Effects � � 3 keV Arsenic � � Doses 1e13, 1e14, 1e15 and 1e16/cm2 � � Note increasing depth of amorphization but damage tail remains fairly constant after onset of amorphization - 22 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Damage Profiles and Amorphization - Dose Effects � � 100keV Phosphorus, (0 tilt) � � Measured (diamonds) and simulated data over-layed � � Doses of 1e13, 5e13, 2e14, 5e14 and 1e15/cm2 R.J. Schreutelkamp et al., “Channeling Implantation of B and P in Silicon”, Nuclear Instruments and Methods, B55, pp. 615–619, 1991 - 23 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Damage Profiles and Amorphization � � 3keV Phosphorus � � Dose 1e13/cm3 � � Showing phosphorus (red), interstitials (green), vacancies (dark blue) and net defects (light blue) - 24 - MC Implant 1D/2D Monte Carlo Implantation Simulator
Using Statistics to Accelerate Simulation Times � � 100keV Phosphorus, (0 tilt) � � Measured (diamonds) and simulated data over-layed � � Doses of 1e13, 5e13, 2e14, 5e14 and 1e15/cm 2 � � Statistics increase chances of rare event occurrences improving tail profiles for a given number of simulated ions - 25 - MC Implant 1D/2D Monte Carlo Implantation Simulator
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