Semiconductor Process Technologies

Semiconductor Process Technologies

ECE222 First Transistor

1947 Bardeen Brattain and Shockley invented the first point- contact transistor.

2 http://www.porticus.org/bell/belllabs_transistor.html First Planar Transistor: Fairchild 2N1613

Jean Hoerni, Fairchild Semiconductor, 1959 Silicon NPN Planar Transistor Protective oxide layer on top

3 http://semiconductormuseum.com/PhotoGallery/PhotoGallery_2N1613.htm First MOSFET

M.M. Atalla and Dawon Kahng, Bell Labs, 1959 MOSFET Transistor

4 First Integrated Circuit

Jack Kilby, Texas Instruments, 1958 First IC: five resistors and capacitors on a germanium substrate

5 http://www.computerhistory.org/timeline/?category=cmpnt First Monolithic IC

Fairchild Semiconductor, 1961 Resistor-transistor logic (RTL) flip-flop

6 http://www.computerhistory.org/timeline/?category=cmpnt From Transistor to Integrated Circuit

Vacuum tube

Integrated circuits Point-contact (1961) transistor (1947)

Diffused-base transistor (1955) Junction bipolar transistor (1951)

Dates in parenthesis are when the technology was invented.

7 Modern VLSI

IBM Power5 Microprocessor Copper Interconnect

8 MOSFET Device Structure

Polysilicon Aluminum

9 MOSFET Device Structure: Cross Section

10 Integrated Circuit Process Flow

11 Crystal Growth

12 Silicon Crystal Ingots

13 Silicon Wafer

14 Oxidation

15 Oxidation

16 Chemical-Vapor Deposition (CVD)

Used for deposition of • Silicon films: epitaxy layer, polysilicon • Dielectric Films: SiO2, Nitride, … 17 • Metals: aluminum, tungsten, TiN, … Sputtering for Metallization

Ion beam

18 Photolithography: Shadow Printing

UV Light

19 Lithography: Projection Printing

(a) annual-field wafer scan (b) 1:1 step-and-repeat

20 (c) M:1 reduction step-and-repeat (d) M:1 reduction step-and-scan Pattern Transfer by Photolithography

Positive Negative Resist Resist

A big advantage of silicon vs. GaAs is that SiO2 can be used as the mask for silicon in pattern transfer 21 Liftoff Process

Used extensively for discrete devices such as power MOSFETs 22 Wet Chemical Etching

Material Etchant

Si HNO3+HF

SiO2 HF (or NH4F)

Si3N4 HF or H3PO4

Al H3PO4+…

23 Orientation-Dependent Etching of Single-Crystal Silicon

24 Plasma-Assisted Dry Etching

Plasma Etching Mechanisim Reactive Ion Etching (RIE) Reactor

Silicon Trenches by Deep RIE

25 Wet Etching vs. Dry Etching

Wet Etching: •Isotropic • Loss of resolution in pattern transfer

Dry Etching: • Anisotropic • High-fidelity transfer 26 Chemical-Mechanical Polishing (CMP)

27 Metal Patterning: Damascene Process

28 Impurity Doping: Diffusion & Ion Implantation

29 Diffusion

30 Ion Implantation

31 Packaging

Chip Package Wirebond

Chip-Stack 32 Flip-Chip Further Reading • Sedra & Smith, A.1 •S.M. Sze, Semiconductor Devices: Physics and Technology, 2nd ed., Wiley, 2002 • International Technology Roadmap for Semiconductors, http://public.itrs.net

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