Cn 4217 - Processing Of Microelectronic Materials

Front 1

What is the primary function of an electronic device?

Back 1

Generation and control of electron flow

Front 2

What is the function of a vacuum tube?

Back 2

For switching and amplification of electric signals; controlled flow of electrons in vacuum

Front 3

What is the difference btw solid state and technology and vacuum tube?

Back 3

SOlid state employs electron crossing junctions in Si and Ge

Front 4

What are the advantages of Si over Ge?

Back 4

1) Si easily oxidised to form high-quality insulator
2) Oxide layer is excellent barrier layer for selective diffusion in IC fabrication
3) Abundant and low cost
4) Wider bandgap thus can operate at higher temp

Front 5

What are the advantages of Cu over Al as an interconnect material?

Back 5

Al has protective natural oxide layer but prob with high current density; Cu has greater stability at high current density

Front 6

What are the stages in IC fabrication?

Back 6

1) Wafer preparation
2) Wafer fabrication
3) Wafer test/sort
- Individual chip is probed and tested
4) Assembly and packaging
5) Final test

Front 7

What are the differences between the types of chip producers?

Back 7

1) Merchant chip supplier
- fabricates chips and sells in open market
2) Captive chip producer
- Fabricates chips for in-house use
3) Fabless company
- Design chips for a particular market
4) Foundry
- Produces chips for other companies

Front 8

What are the major trends in the semiconductor industry?

Back 8

1) Increase in chip performance
2) Increase in chip reliability
3) Reduction in chip price

Front 9

How is the increase in chip performance being carried out?

Back 9

1) Coordinated reduction of device dimensions (critical dimensions) in the lateral and vertical directions
2) Moore's law estimates that the no. of transistors on chip will double every year (reality: doubles every 18 months)
3) Chip power consumption grows at a slower rate than the increase in the no. of transistors per chip

Front 10

How is the increase in chip reliability being carried out?

Back 10

1) Contamination is controlled through strict cleanroom protocols
2) Fabrication processes are constantly analysed

Front 11

How is the reduction in chip price being carried out?

Back 11

1) Critical dimension is reduced, so more devices per chip at almost the same manufacturing cost per wafer
2) Companies produce large volume - economies of scale

Front 12

What are the economics of integration and minituarization?

Back 12

1) Device performance basis
- integration permits assembly of different functions cohesively
- device speed is inversely proportional to device feature length
- power consumption is directly proportional to square of device feature length
2) Cost basis
- integration reduces processing cost per function
- large no. of identical devices produced simultaneously
- large wafers means more devices per wafer with fractional increase in processing cost

Front 13

What are the steps in the semiconductor manufacturing process?

Back 13

1) Si wafer
2) Deposit Si3N4 in CVD furnace
3) Etch transistor areas using photoresist
4) Implant ions
5) Grow field oxide using oxidation furnace
6) Grow gate oxide using oxidation furnace
7) Deposit polySi using CVD furnace
8) Etch polysilicon gate definition using photoresist mask
9) n+ source drain diffusion through diffusion furnace
10) Deposit SiO2 in CVD furnace
11) Etch contact areas using photoresist mask
12) Deposit Al in vacuum evaporator
13) Metal deifnition using photoresist mask
14) Protective passivation
15) Expose bonding pads using photoresist mask
16) Probe wafer
17) Die separation
18) Die attach
19) Wire bonding
20) Final test