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Base = PBase (3rd counter doping) PSD (for contact) ... PBase = 3rd impurity doping higher Irec (IB = Irec ... doped Base. If too lightly doped surface ... – PowerPoint PPT presentation

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Title: Course Project:


1
  • Course Project
  • Analog (or mixed signal) IC
  • Teams -- 2-3 people
  • Deadlines

2
  • 3.3.3 Available Devices -- BiCMOS
  • All devices from CMOS LDD NMOS, SDD PMOS, ED HV
    NMOS, Resistors (Poly-1, PSD, NSD, and Nwell)
  • - others

Ex) Extended Drain High-Voltage NMOS
LAYOUT
XSECTION
3
  • 3.3.3 Available Devices -- BiCMOS
  • All devices from CMOS LDD NMOS, SDD PMOS, ED HV
    NMOS, Resistors (Poly-1, PSD, NSD, and Nwell)
  • - others

Ex) Extended Drain High-Voltage NMOS
LAYOUT
XSECTION
4
  • (1) NPN Transistor
  • Collector NWell NBL Deep-N NSD (for
    contact)
  • Base PBase (3rd counter doping) PSD (for
    contact)
  • Emitter NSD (emitter diffusion and contact)
  • Comments
  • Emitter area EBJ area for injection
  • PBase 3rd impurity doping ? higher Irec (IB
    Irec ..) ? lower b. ? b is
    typically aimed at 50 or 75(1 - 0.5)
  • Without Deep-N, Collector has too high
    Resistance ? soft transistion between
    Saturation and Active regions ?
  • Zeners do not require deep-N because not much
    current flows in Collector.
  • BiCMOS NPN vs. Standard NPN

5
NPN Bipolar
Layout
Xsect
6
NPN Bipolar
Layout
Xsect
7
  • (2) Substrate PNP
  • Same as in Polygate CMOS
  • PSD implant into NWELL ? Emitter
  • NWELL ? Base
  • P-epi on P-sub ? Collector

8
Substr. PNP (same as in CMOS)
9
Substr. PNP (same as in CMOS)
Lateral PNP (BiCMOS only)
10
  • (3) Lateral PNP
  • P-Base diffusion of NPN ? Emitter Collector of
    PNP,
    formed in NWELL.
  • Role of NBL in lateral PNP
  • Depletion stop
  • Blocks punchthrough breakdown
  • Allows deeper Pbase (NPN) implant for E C (rid
    of shallower PSD implant) ? Increase
    Sidewall area ! ? higher b 100 (vs. b
    lt10 w/o NBL)

11
Lateral vs. Substrate PNP
12
  • (4)Resistor
  • PBase resistor in NWELL
  • Rs 500 W/sq. for lightly doped Base
  • If too lightly doped ? surface depletion is
    problem.
  • Not much better than Poly resistors, only if
    larger area is affordable.

Layout
Xsection
13
  • SCMOS Layout Questions about
  • Verical NPN Bipolar Transistor gt Y
  • Lateral PNP Transistor gt No
  • Poly Capacitor gt Y

14
AMI_ABN Run Examples
NPN b 110 - 130 VA about 50 V
Poly Capacitor C 0.6 fF/mm2
15
Summary Review of IC Analog Circuits Building
Blocks
  • CMOS circuit blocks
  • BiCMOS circuit blocks
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