IC Transistors and Resistors

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IC Transistors and Resistors

1. Resistors
2. Bipolar Transistors
3. MOS
4. DMOS

Chris Kendrick Jan. 29, 2003 BiCMOS Design
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Resistor Voltage Coefficient
Figure 1 A p type region in an n type tub forms
the resistor.
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Resistor Voltage Coefficient
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Resistor Temperature Coefficient
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Resistor Voltage limits

• The maximum resistor voltage is NOT defined by
  the tub its sitting in!

Diffusion Breakdown (V)
Buried Layer Isolation 95
PWell Epi 95
PHV Epi 60
NHV - PWell 43
PSD - Epi 30
NSD - PWell 17.5
NSD PHV 12
NSD PSD (in PWell) 5.8

• The voltage rating of the tub determines the
  spacing of PHV to Epi

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Lateral PNP Saturation
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Low current NPN/PNP biasing

• Whats the lowest current bipolars can be biased
  at?

Lateral PNP
ICmin 5uA
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Low current NPN/PNP biasing

• Whats the lowest current bipolars can be biased
  at?

Vertical PNP
ICmin 20nA
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Low current NPN/PNP biasing

• Whats the lowest current bipolars can be biased
  at?

NPN
ICmin 20nA
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MOS Safe Operating Area

• Hot carrier injection limits NMOS operating
  voltage

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LV NMOS Hot Carrier Injection

• Maximum Vds determined from HCI measurements 10
  degradation in 10 yrs
• Transient Vds rating based on 10 duty cycle

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LV LVT PMOS drain-source leakage

• Drain-source leakage determines maximum Vds at
  high temperature
• Minimum channel length targeted based on process
  variation and independent SEM measurement

150C
27C
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DMOS Specific Rdson
Rsp Rdson x transistor active area
transistor active area cells x cell area
Device Rdson (W) Area (cm2) Rsp. (mW.cm2)
LV NLDMOS 0.66 5.19E-4 0.34
MV1 NLDMOS 1.93 7.32E-4 1.41
LV PLDMOS 2.58 5.19E-4 1.34
MV PLDMOS 4.92 7.32E-4 3.6
VDMOS_HEC 1.53 1.77E-3 2.7
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DMOS Specific Rdson

• More components to Rdson than just channel
  resistance
• RCH REpi RBL RMetal

• Series resistance causes bend in ID vs. VG
  curve

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A useful way to extract DMOS series resistance
   
(1)
(2)
Substituting (2) into (3) gives,
(3)
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DMOS Clamped Inductive Switching

• Clamping the flyback voltage below the DMOS
  breakdown increases energy capability.
• Power dissipation eventually allows parasitic
  bipolar to turn on, killing device

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Energy capability can determine device size