Budapest University of Technology and Economics
Department of Electron Devices
Microelectronics, BSc course
Bipolar IC technology: set
of elements
http://www.eet.bme.hu/~poppe/miel/en/09-bipIC.ppt
http://www.eet.bme.hu
Budapest University of Technology and Economics
Department of Electron Devices
Set of components
available in bipolar IC-s
►
Resistor with base diffusion
► Resistor + emitter diffusion
► PNP transistors
► Thin film capacitance
► Layout of an OpAmp
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
2
Budapest University of Technology and Economics
Department of Electron Devices
Element set available in bipolar
IC processes
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
3
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Detail of a bipolar IC – as seen by a scanning electron microscope
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
4
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
npn (vertical) transistor
Island (well)
Substrate
Base
23-10-2010
Emitter
Buried
layer
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
5
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
the isolation diffusion
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
6
Budapest University of Technology and Economics
Department of Electron Devices
Structure of an npn IC transistor
Island
(well)
Substrate
Base
Emitter
Buried
layer
metal
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
7
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
npn transistors
Process
optimized for
the npn
(vertical)
transistors
Effective emitter edge at the base contact side (I=2 A/cm),
EB br.down: 5-6 V, CB br.down 40-50 V, fT=800-900 MHz
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
8
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
High current npn transistors
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
9
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Different npn transistors
Area efficient solutions:
two transistors in a common isolation well,
multi-emitter transistor
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
10
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Different npn transistors
Effective emitter edge at the base contact side (I=2 A/cm)
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
11
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Resistor with base diffusion
D  dx
D B
G  
 q   p N B ( x)dx
L
L 0
0
dB
R
island
(well)
d
1
dB
q   p N ( x)dx
0
L
RR
D
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
12
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Resistor with base diffusion
There could be multiple resistors in the
same isolation well
23-10-2010
The well must be connected to +UCC!
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
13
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Resistor with base
diffusion, folded as
a meander
R  100  150
R  100  10 K
R
  0. 1% / C
T
Accuracy,
parasistics
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
14
Budapest University of Technology and Economics
Department of Electron Devices
How to make components VERY
MUCH identical?
• same layout shape
• same position
• close to eachother
• larger than minimal size
• same temperature
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
15
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Resistor with base diffusion, cross section
reduced by emitter diffusion
R
1
dB
q   p N ( x)dx
dE
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
16
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Resistor with base diffusion, cross section
reduced by emitter diffusion
value: few times 100 k
emitter diffusion
base diffusion
Slightly nonlinear
Limited voltage range
R
1
dB
q   p N ( x)dx
dE
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
17
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
small emitter diffusion resistor
(connection underpass), value
cca. 2 
Emitter
diffusion
Metallization
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
18
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Lateral pnp transistor
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
19
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Lateral pnp transistor
Multiple transistors
in common well
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
20
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Lateral pnp "sector" transistors
overlapping contact window
Forms a current mirror
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
21
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Lateral pnp "sector" transistors
I
23-10-2010
I
Also with
circular
shape!
I
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
3I
22
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Vertical pnp transistor
vertical pnp
structure
n+ no
buried
layer
push and
pull
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
amplifier (B)
23
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
The thin film capacitor
Metal
dox: 0,1 m (50 V)
Cspec: 3-400pF/mm2
23-10-2010
6
A
10
C   0 r  8,86 1012  3,9  7  345 1012 F
d
10
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
24
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Thin film (metal-SiO2-n+) capacitor in an OpAmp
Value: cca. 30pF
Cspec: 3-400pF/mm2
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
25
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
Thin film (metal-SiO2-n+) capacitor in an OpAmp
Compare the size of the capacitor and the transistors!
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
26
Budapest University of Technology and Economics
Department of Electron Devices
Element set in bipolar IC-s
The pn junction as a capacitor
The space charge capacitance can be
utilized, but
• voltage dependent (non-linear)
• may not be forward biased!
23-10-2010
EB: 1000pF/mm2
(up to 5 V)
CB: 150pF/mm2
(up to ~50 V)
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
27
Budapest University of Technology and Economics
Department of Electron Devices
OpAmp
layout,
component arrangement
Symmetry – to assure
same thermal feedback
path.
This layout is not yet the
best.
23-10-2010
T1, T2: NPN, input differential
pair
T3, T4: PNP, lateral
T5, T6, T7: NPN
T10, T11, T13: PNP
lateral transistors
D1, D2: diodes
T16-17: NPN darlington
T19-21: 3 NPN transistors in a
common well
R1, R6: large resistors
R7: base+emitter diff. resistor
R8, R9: small resistors
T22: PNP vertical
T23: NPN vertical
(high current)
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
28
Budapest University of Technology and Economics
Department of Electron Devices
Thermal effects in analog
IC-s: a bipolar OpAmp
►
►
►
►
23-10-2010
Thermal impedances
Thermal feedback in case of an OpAmp
How does the layout influence the thermal feedback
Layout – thermally optimized
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
29
Budapest University of Technology and Economics
Department of Electron Devices
The thermal impedances
The transfer impedance
The self impedance
T1 temperature rise
T1
Rth 
[K / W ]
P1
T1 ( )
Z th ( ) 
P ( )1
Z th12 ( ) 
T2 ( )
P1 ( )
Zth complex valued
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
30
Budapest University of Technology and Economics
Department of Electron Devices
Thermal feedback – in an OpAmp
Stationary state,
VOUT > 0


PT 14  VCC
 VOUT
VR
OUT
L
T  Z141  Z142 PT 14
Vequ   ( Z141  Z142 )V

CC
VOUT
 VOUT 
RL
  -2 mV/oC
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
31
Budapest University of Technology and Economics
Department of Electron Devices
Thermal feedback – in an OpAmp
Stationary state
Effect on the open
loop characteristic
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
32
Budapest University of Technology and Economics
Department of Electron Devices
Thermal feedback – in an OpAmp
Methods for analysis
Both measurements and simulations were done.
A well known, commercially available circuit was studied
(A741 OpAmp).
Both stationary state and dynamic behaviour.
Identical type from different IC venors: different layout
designs realizing the same electrical schematic.
Actual layout (component arrangement) was identified by
"reverse engineering".
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
33
Budapest University of Technology and Economics
Department of Electron Devices
Details of the model
Device under test: A741 OpAmp
Physical layer
structure
Schematic of the
OpAmp
Yellow transistors considered by electro-thermal model
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
34
Budapest University of Technology and Economics
Department of Electron Devices
Reverse engineered layouts
Layout "A"
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
35
Budapest University of Technology and Economics
Department of Electron Devices
Reverse engineered layouts
Layout "B"
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
36
Budapest University of Technology and Economics
Department of Electron Devices
Open loop characteristics
(measurement and simulation)
Layout "A"
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
37
Budapest University of Technology and Economics
Department of Electron Devices
Open loop characteristics
(measurement and simulation)
Layout "B"
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
38
Budapest University of Technology and Economics
Department of Electron Devices
Frequency domain analysis
Thermal effects in the output impedance
Z OUT (ω) 
23-10-2010
Re
Gv (ω)


(VCC
 VOUT )γ( Z141  Z142 )
1  βGv (ω) 1  βGv (ω)
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
39
Budapest University of Technology and Economics
Department of Electron Devices
Frequency domain analysis
Layout "A", upper transistor on, G=104
Effect appears even if there
is no load!
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
40
Budapest University of Technology and Economics
Department of Electron Devices
Frequency domain analysis
"A"
"B"
Difference only in layout!
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
41
Budapest University of Technology and Economics
Department of Electron Devices
The ideal layout
"A"
"B"
Input differential
pair
Output transistors
(common centroid)
23-10-2010
Microelectronics BSc course, Element set in bipolar IC-s © András Poppe & Vladimír Székely, BME-EET 2008-2011
42