DILBERT

Summary of Project to Date Did research and learned about several communication devices – cellular phones, Bluetooth/Wi-Fi, and RFID Received silicon wafer to be used as base for antennas – could use other substrates if equipment was available Received a traveler defining the steps necessary to fabricate your antenna Cleaned silicon wafers to provide a contamination free surface Grew SiO2 (silicon dioxide) to provide an insulating dielectric surface Determined your application, either cellular, Bluetooth/Wi-Fi, or RFID Determined how to find the correct length for the antenna based on the application Using a decision matrix determined the conductor to be used to fabricate the antenna This week will deposit conductor of choice

Thin Film Deposition Conductors are deposited using a vacuum chamber The vacuum chamber reduces the atmosphere to high vacuum levels (no atmosphere) This reduces contaminating the films, provides a non-contaminating environment free of oxygen, water vapor, etc. and allows materials to melt at lower temperatures.

Thin Film Deposition Thin film deposition tools are very complex due to the need to create high vacuum levels. Vacuum levels of 5x10-7 torr and better are typical. Sea level atmospheric pressure is about 740 torr or 7.4x102 Because of their complexity, vacuum chambers are very expensive.

Thin Film Deposition To achieve high vacuum levels, several types of vacuum pumps are used. Mid level vacuum levels (2x10-3 torr) are reached with rotary vane vacuum pumps. These pumps are also know as mechanical or roughing vacuum pumps High level vacuum levels are reached using Diffusion vacuum pumps – requires liquid nitrogen to prevent oil contamination Turbomolecular pumps – like a small jet engine, clean and fast, good for processes that require the introduction of a process gas. Because of the high speed vanes, subject to catastrophic failure Cryogenic vacuum pumps – uses low temperature (10oK) – also clean and fast pumping but requires regeneration periodically which is time consuming

Thin film deposition tools in the ECE Microelectronics Clean Room Cooke-thermal deposition CVC 601-sputter deposition CHA Mark 50 e-beam deposition Varian 3125 e-beam deposition

Conductor Deposition The Cooke thermal evaporator is not currently used. The CVC sputter tool is used only for aluminum depositions. Only an aluminum target is available. The Varian 3125 and CHA Mark 50 e-beam deposition tools are used for all other conductors, Cu, Au, Ag, Cr, Ni An e-beam evaporates material, it get the material so hot it becomes a gas and evaporates. It then travels in a straight line, because it is under vacuum, until it condenses when it strikes a colder surface

With sputtering, an Argon plasma is formed, causing argon ions to strike a metal target and knock loose material. Because an electric field is created, material is deposited on the substrate Argon plasma – ionized argon in an electric field Material target Substrate to be coated

E-beam Evaporation uses a high energy electron beam to vaporize (change from a solid to vapor) materials, especially metals

Overall view of the Varian 3125 vacuum chamber Overall view of the Varian 3125 vacuum chamber. This tool deposits thin films using e-beam evaporation

Portion of Varian 3125 control rack

Varian 3125 quartz heater controller, shutter controller and planetary rotation controller E-beam shutter controller Planetary (wafer holder) rotation controller

Electron beam power supply Electron beam can be steered by magnetic fields Typically 6-8KV are required to form the electron beam

Cryopump temperature-must be below 15oK

Varian 3125 ion gauge controller and deposition controller

Varian 3125 view of open chamber Wafer planetary – can rotate or stay stationary. Can be removed for loading

Varian 3125 4-pocket e-beam crucible

With an e-beam (electron beam) evaporator the material is heated to a vapor (gas) and then condenses on cooler surfaces Substrates (wafers) sit at the top of the chamber Electron beam is formed and strikes the metal crucible Molten material hot enough to vaporize (become a gas)

Varian 3125 wafer planetary Wafer planetary for Varian 3125

Wafers are held down by spring clips Varian 3125 Wafers are held down by spring clips

Varian 3126 Quartz Heaters

Varian 3125 door showing glasds slide holder Glass slide must be replaced before each run

Overall view of the CHA Mark 50 vacuum chamber Overall view of the CHA Mark 50 vacuum chamber. This tool deposits thin films using e-beam evaporation

Inside of CHA Mark 50 chamber showing wafer platen – can not be removed from the chamber

CHA Mark 50 wafer adapter ring Adapter ring for 4”/100mm wafer Adapter rings are available for 2”, 3” and 4” wafers

CHA Mark 50 4-pocket e-beam crucible Four different materials are available to do sequential evaporations

CHA Mark 50 crucible materials and chamber temperature monitor Materials currently inside the 4 pocket crucible are shown with their pocket number Pocket is chosen using this indexer

CHA Mark 50 crystal oscillators for evaporation material thickness measurement

New glass slides must be used for each evaporation

CHA Mark 50 cryo-pump control Cryogenic pump temperature – should be less than 15oK

CHA Mark 50 vacuum gauge controller Vacuum chamber pressure of 7.5 x 10-7 torr

CHA Mark 50 E-beam power supply and controller High voltage switch and current control Power supply main on/off switch Power supply is interlocked to prevent activation if vacuum pressure, cooling water, and zero current conditions are not met

Crucible being heated by an electron beam E-beam evaporation Crucible being heated by an electron beam

Overall view of the CVC vacuum chamber Overall view of the CVC vacuum chamber. This tool deposits thin films using “sputtering”

CVC sputter tool with chamber lid open Wafers are loaded into position

Looking into the CVC sputter tool chamber, showing the 8” aluminum target

CVC sputter tool control racks Ion gauge

Argon MFC – 30 sccm flow typical Cryo pump temperature – must be below 16oK

CVC sputter tool DC power supply for aluminum target DC Voltage about 4KV DC current 0.5 to 1.0 A

CVC sputter tool view port

View of argon sputter plasma in CVC sputter tool

View of argon plasma in AJA sputter tool Sputter target Shutter Substrate (wafer) stage Wafer stage can rotate and heat

Homework Assignment Due next class meeting Review “Mask design steps” from web site Read “Designing Antennas for Cellular Telephones” from web site. Find “AutoCad” on Mosaic – listed under Mechanical Engineering as AutoCad 2006 Become familiar with AutoCad. There is a tutorial on my web site Begin preliminary dimension sketches for your antenna design Maximum size 20mmx20mm Minimum size 5mmx5mm Line width – 1mm Spacing between lines – 1mm or greater No sharp corners Must be able to fit inside a box to allow cutting into individual antenna Length must match your design length Can be any design – be creative Dimension drawing of your design is required

Simple spiral design

Cingular Logo design

XBOX design Note-DO NOT USE WHITE ON BLACBACKGROUND

Football Design- DO NOT USE WHITE ON DARK BACKGROUND

UNC-Charlotte Crown design

Dimensions not in a contrasting color