Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
Uploaded bysumit__kumar
PPTX, PDF4,926 views

why and how thin films

Thin films are layers of material ranging from 10-500 nanometers thick. Thin film technology is used in many applications like microelectronics, optics, and magnetic coatings. There are various deposition techniques used to fabricate thin films, including physical vapor deposition methods like sputtering and evaporation, and chemical vapor deposition methods like plasma-enhanced CVD and low-pressure CVD. Each deposition technique has advantages and disadvantages depending on the substrate and material properties. Thin films are used to produce microelectronics, sensors, tailored materials, optical coatings, and corrosion/wear resistant coatings.

Education◦
Downloaded 155 times
INTRODUCTIONTO THINFILMS TECHNOLOGY Presented by : Sumit Kumar
Thin Films ???  Thin films are just a layer of materials, thickness ranging between (10-500) nanometers  If there is no substrate then it is a “foil”. fig: Zno thin film deposited on a substrate
Why Thin Films ???  Maintain surface uniformity  Simple fabrication  Manufacturing requires less material  Reduce light absorbing material  Strange electrical, optical and mechanical properties
• Nowadays thin film technology used in many applications, including microelectronics, optics, magnetic, hard resistant coatings, micro-mechanics, etc. • Better results in these areas depend on selective and controlled deposition. • There are a vast number of deposition methods available, all methods have their specific advantages as well as disadvantages based on substrate and source material, thickness of deposited film. • This makes it difficult to select the best technique for any specific application. Some of these methods are discussed. Technology Focus
Deposition Techniques  Glow Discharge Processes 1. Sputtering 2. Plasma processes  Gas phase chemical processes 1. Low Pressure CVD 2. Metal Organic CVD 3. Laser induced CVD  Liquid Phase Chemical Processes 1. Electroplating 2. Spin on Techniques
. • Vacuum evaporation Techniques 1. Convential Vacuum Evaporation 2. Molecular Beam evaporation 3. Molecular Beam Epitaxy 4. Reaction Evaporation
.Deposition based on Physical or Chemical Processes Deposition Techniques PhysicalVapor Deposition Vacuum Evaporation Techniques Sputtering Spin Coatings Chemical Vapor Deposition Electroplating PECVD LPCVD
Plasma Enhanced CVD . • Lower Temperature Process due to Plasma Enhancement • Dissociation of precursor gas molecules (Homogeneous reactions) • Ions bombard surface making it more reactive • Higher rates of deposition are possible than with LPCVD
Low Pressure CVD  . • Surface reaction limited at low pressure • Chamber may also be heated or unheated • Low pressure environment increases mean free path • Better Step Coverage and conformality than APCVD
Electroplating
Sputtering • It is basically an etching process which was first discovered in 1892 and developed as a thin film deposition techniques in 1920 by Langmuir.
Spin Coating
Evaporation Deposition The material is heated in high vacuum chamber (P < 10-5 Torr) to minimize the collision in source atoms, it is also called Vacuum Deposition. Heating is done by resistive or e-beam sources. Surface interactions are physical, can be very fast (>1m/min possible) High sticking coefficient leading to poor conformal coverage/significant shadow. But this also makes evaporation the most popular thin film deposition for nanofabrication using liftoff process. Deposition rate is determined by emitted flux and by geometry of the source and wafer. Evaporation is not widely used by industry as sputter 13
 Evaporator based on heating process 1. Thermal Evaporator(Resistive heating) 2. Electron beam Evaporator(Heating by electron beam) 3. Inductive Evaporator (Inductive heating – most unpopular one)
Thermal Evaporator  Used for material whose vapor pressure can be reasonable at (1600-1800)°C or less than that. Common evaporant materials are Au, Ag, Al, Sn, Cds, Pbs, Cdse etc.
 Thermal Evaporator 1. Simple, used at large scale 2. W, Ta filaments are used as heaters. 3. Filament produces current to (200-300) ampere. 4. Substrate exposes to Infrared or Visible rays 5. Contamination from heated boat  E-Beam Evaporator 1. More complex and can be used for almost all kind of materials . 2. Less contamination and heating to wafer. 3. Exposes substrate to secondary electron radiation 4. X-Ray can be generated by high voltage electron beam. As it produces X-ray beams so it can’t be used for MOSFET(X-ray may damage substrate as well as dielectrics)
Issues with Evaporation System  Step Coverage  Alloy Evaporation  Shadow Evaporation
Types of Thin Films  Si based thin films  CdTe Thin Films  CIGS Thin Films  CZTS Thin Films
Applications • Microelectronics - electrical conductors, electrical barriers, diffusion barriers. • Magnetic sensors - sense I, B or changes in them • Gas sensors, SAW devices. • Tailored materials - layer very thin films to develop materials with new properties • Optics- anti-reflection coatings • Corrosion protection • Wear resistance
Thank You