330 EE Lecture 12
Devices in Semiconductor Processes
Quiz 11
A wire obtained with a ball bond is shown sitting on a bonding pad. What is a typical value for the dimension d1 shown?
d1=?
And the number is ....
1
8
3
5
4
6
9
7
2
And the number is ....
1
7
4
9
6
3
8
5
3
2
Quiz 11
A wire obtained with a ball bond is shown sitting on a bonding pad. What is a typical value for the dimension d1 shown?
d1=?
d1=25
Review from Last Time
Back-End Process Flow
Wafer Probe Wafer Dicing Die Attach
Wire Attach (bonding)
Package
Test
Ship
Review from Last Time
Wafer Dicing
www.renishaw.com
Review from Last Time
Die Attach
1. Eutectic 2. Pre-form 3. Conductive Epoxy
Review from Last Time
Electrical Connections (Bonding)
Wire Bonding Bump Bonding
Basic Semiconductor Processes
MOS (Metal Oxide Semiconductor)
1. NMOS 2. PMOS 3. CMOS
Basic Device: Niche Device: Other Devices:
n-ch p-ch n-ch & p-ch
MOSFET MESFET Diode BJT Resistors Capacitors Schottky Diode
Basic Semiconductor Processes
Bipolar
1. 2. 3. 4.
T2L ECL I2L Linear ICs
Basic Device: Niche Devices: Other Devices: BJT (Bipolar Junction Transistor) HBJT (Heterojunction Bipolar Transistor) HBT Diode Resistor Capacitor Schottky Diode JFET (Junction Field Effect Transistor)
Basic Semiconductor Processes
Other Processes Thin and Thick Film Processes
Basic Device: Resistor
BiMOS or BiCMOS
Combines both MOS & Bipolar Processes Basic Devices: MOSFET & BJT
SiGe
BJT with HBT implementation
SiGe / MOS
Combines HBT & MOSFET technology
SOI / SOS (Silicon on Insulator / Silicon on Sapphire) Twin-Well & Twin Tub CMOS
Very similar to basic CMOS but more optimal transistor char.
Devices in Semiconductor Processes
Standard CMOS Process
MOS Transistors
n-channel p-channel
Capacitors Resistors Diodes BJT ( decent in some processes)
npn pnp n-channel p-channel
JFET (in some processes)
Standard Bipolar Process
BJT
npn pnp n-channel p-channel
JFET
Diodes Resistors Capacitors
Niche Devices
Photodetectors (photodiodes, phototransistors, photoresistors) MESFET HBT Schottky Diode (not Shockley) MEM Devices ....
Basic Devices
Standard CMOS Process
MOS Transistors
n-channel p-channel Primary Consideration in This Course
Capacitors Diodes Resistors BJT (in some processes)
npn pnp
Niche Devices
Photodetectors MESFET Schottky Diode (not Shockley) MEM Devices Triac/SCR ....
Some Consideration in This Course
Basic Devices and Device Models
Resistor Diode Capacitor MOSFET BJT
Basic Devices and Device Models
Resistor Diode Capacitor MOSFET BJT
Resistors were discussed when considering interconnects so will only be briefly reviewed here
Resistors
Generally thin-film devices Almost any thin-film layer can be used as a resistor
Diffused resistors Poly Resistors Metal Resistors "Thin-film" adders (SiCr or NiCr)
Subject to process variations, gradient effects and local random variations Often temperature and voltage dependent
Ambient temperature Local Heating
Nonlinearities often a cause of distortion when used in circuits Trimming possible resistors
Laser,links,switches
Resistor Model
W
d L V I
Model:
V R I
Resistivity
Volumetric measure of conduction capability of a material
Area is A units : ohm cm
AR L
L
R for homogeneous material, A, R, L
Sheet Resistance
W
d L R
RW R L
( for d << w, d << L )
units : ohms /
for homogeneous materials, R is independent of W, L, R
Relationship between and R
RW R L
AR L
A R W
A W d
dxR
A Wd R R W W
Number of squares, NS, often used instead of L / W in determining resistance of film resistors
R=RNS
Example 1
W
L
R=?
Example 1
L
L NS W
W
Example 1
.4
8
7
6
5
4
3
2
1
R=?
Example 1
.4
8
7
6
5
4
3
2
1
R=?
NS=8.4
R = R (8.4)
Corners in Film Resistors
Corner
Rule of Thumb: .55 squares for each corner
Example 2
Determine R if R = 100 /
Example 2
1 2 3 4 5 6 .55 1 2 3 1 2 3 4 5 6 7 .55
NS=17.1 R = (17.1) R R = 1710
Resistivity of Materials used in Semiconductor Processing
Cu: Al: Gold: Platinum: n-Si: intrinsic Si: SiO2: 1.7E-6 cm 2.7E-4 cm 2.4E-6 cm 3.0E-6 cm .25 to 5 cm 2.5E5 cm E14 cm
Temperature Coefficients
Used for indicating temperature sensitivity of resistors & capacitors For a resistor:
1 dR TCR 106 ppm C R dT op. temp
This diff eqn can easily be solved if TCR is a constant
T2 T1 106
R T2 R T1 e
TCR
TCR R T2 R T1 1 T2 T1 6 10
Identical Expressions for Capacitors
End of Lecture 12