1. EFFECT OF REACTION PARAMETERS ON EXERGY EFFICIENCY OF ATOMIC LAYER DEPOSITION Al 2 O 3 FILM Fenfen Wang, Chris Yuan Department of Mechanical Engineering, UWM   Understand and improve the energy efficiency of Atomic Layer Deposition (ALD) nanotechnology from a hierarchical systems perspective. Research Object: ALD of Al 2 O 3 thin film process   Establish mathematical modeling of exergy (energy) flow and exergy efficiency of ALD process   Get a better understanding of the effects of reaction parameters on exergy efficiency of ALD process   Optimize ALD technology for the improvement of its energy utilization, thus paving the way for its furture large-scale sustainable applications.   Exergy Definition: The maximum work obtainable when some matter is brought to a state of thermodynamic equilibrium with the reference environment by means of reversible processes. Reference temperature (T 0 ): 298.15 K Reference pressure (p 0 ): 1 atm.   Exergy analysis method Combining the first and second laws of thermodynamics Objective: To identify sites where exergy losses occur and rank order them for significance for the analysis, design and improvement of systems. Importance: Allowing attention to be centered on the aspects of system operation that offer the greatest opportunity for improvement. Firstly, three kinds of exergy efficiency are calculated by changing reaction parameters (N 2 flow rate, reaction temperature and purging time) Then, further analyses of effects of reaction temperature and purging time on exergy efficiency are conducted. [1] George, S. M., Atomic layer deposition: an overview. Chemical reviews, 110 (1), 111-131, 2009. [2] Yuan, C., Dornfeld, D., Environmental performance characterization of atomic layer deposition. Proceedings of IEEE International Symposium on Electronics and the Environment, San Francisco, California. [3] Renaldi, Karel Kellens, Wim Dewulf, Joost R. Duflou, Exergy Efficiency Definitions for Manufacturing Processes. Springer, 329-334, 2011. OBJECTIVESMETHODOLOGYRESULTS (Cont.)   Effect of reaction parameters on exergy efficiencies of Atomic layer deposition (ALD) of Al 2 O 3 thin film is studied.   N 2 flow rate has little effect on exergy efficiency. Exergy efficiencies decrease with the increase of both temperature and purging time.   Reducing reaction temperature and purging time to a certain degree can improve energy efficiency of ALD process.   This research paves the way for future optimization for the improvement of energy utilization and sustainability performance of ALD technology. CONCLUSION BIBLIOGRAPHY Fenfen Wang, Email: fenfen@uwm.edu Chris Yuan, Email: cyuan@uwm.edu CONTACT INFORMATION Results   N 2 flow rate has little effect on all exergy efficiencies.   Reaction temperature and purging time have relatively big influences on exergy efficiencies.   Maximum exergy efficiencies are obtained at: purging time is equal to 4 s (N 2 flow rate and reaction temperature are constant) Reaction temperature is equal to 423K (N 2 flow rate and purging time are constant) ACKNOWLEDGEMENT This study is financially supported by the National Science Foundation (NSF U.S. Grant No. CMMI-1200940)   Exergy efficiencies decrease with the increase of both temperature and purging time.   Purging time has more influence on exergy efficiencies than temperature does. Exergy efficiencies under different reaction parameters   Sustainability issues about ALD technology Heavy wastes of toxic chemicals Nano-particle emissions high material and energy consumptions Nano particle emissions Energy consumption of 300 cycle ALD processes at 473 K [2] energy consumption (KJ) B Physical exergy B ph Chemical Exergy B ch Material flow exergy B W =W Work flow exergy B Q =(1-T 0 /T)Q Heat flow exergy System State Reference State Exergy=Maximum work attainable by returning the system from the System State to the Reference State Exergy (B) B in (1-T 0 /T)Q in W in B out (1-T 0 /T)Q out W out Exergy flow in a system [3] Transiting exergy in the useful output stream B tr,u Exergy output B out Transiting exergy in the input stream B tr,in Exergy input B in Internal exergy lossess B loss,int External Exergy Lossess B loss,ext Transiting exergy in the losses stream B tr,loss Useful Exergy output B u Exergy efficiency under different reaction temperatures Exergy efficiency under different reaction temperatures Introduction   Importance of ALD technology [1]: Semiconductors 90nm 45nm Atomic layer growth of thin films Diffusion Adsorption Reaction Dissociation Dielectric miniaturization Sample Channel gate drain source Need for high k dielectric films Channel drain Dielectric layer source   Deposition mechanism of ALD Al 2 O 3 ALD of Al 2 O 3 cycles CH 4 TMA CH 3 surface OH surface CH 4 N2N2 Purge H2OH2O Repeat TMA Cambridge Nanotech SavannahALD of Al 2 O 3 cycles S100 ALD system chamber Carrier gas line Vacuum valve manifold Precursor cylinder Stop valve Reactions N 2 flow rate (sccm) Reaction temperature (K) Purging time (s) 1 204234 2 204734 3 205234 4 20423 8 5 20473 8 6 205238 7 2042312 8 2047312 9 2052312 1030 4234 1130 4734 1230 5234 1330 423 8 1430 473 8 1530 5238 1630 42312 1730 47312 18 3052312 19 404234 2040 4734 2140 5234 2240 423 8 2340 473 8 2440 5238 2540 42312 2640 47312 2740 52312