Sensors
and
Actuators
A
289
(2019)
11–18
Contents lists available at ScienceDirect
Sensors
and
Actuators
A:
Physical
journal homepage: www.elsevier.com/locate/sna
Compact
micro-Pirani
vacuum
sensor
based
on
series
diodes
without
heating
structure
Debo
Wei
a,b
,
Jianyu
Fu
a,b,∗
,
Ruiwen
Liu
a,∗∗
,
Ying
Hou
a
,
Chao
Liu
a,b
,
Weibing
Wang
a,b
,
Dapeng
Chen
a,b
a
Smart
Sensing
Research
and
Development
Centre,
Institute
of
Microelectronics,
Chinese
Academy
of
Sciences,
Beijing
100029,
China
b
University
of
Chinese
Academy
of
Sciences,
Beijing
100029,
China
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
26
October
2018
Received
in
revised
form
15
January
2019
Accepted
13
February
2019
Available
online
14
February
2019
Keywords:
Series
diodes
Micro-Pirani
vacuum
sensor
CMOS
compatible
Heating
structure
a
b
s
t
r
a
c
t
Diode
based
micro-Pirani
vacuum
sensors
attract
considerable
attention
because
they
do
not
require
special
materials
and
are
compatible
with
complementary
metal
oxide
semiconductors
(CMOS).
How-
ever,
their
complex
heating
structure
makes
it
difficult
to
reduce
the
sensor
size.
This
paper
reports
a
novel
compact
micro-Pirani
vacuum
sensor
based
on
series
diodes.
The
self-heating
effect
of
the
series
diodes
helps
simplify
the
structural
design
by
avoiding
a
dedicated
heating
structure.
Moreover,
the
small
size
of
the
series
diodes
ensures
high
temperature
coefficient.
The
proposed
design
reduces
the
sensor
size
without
sacrificing
the
performance.
In
fact,
simulation
results
indicate
that
the
series
diodes
help
enhance
the
device
performance.
A
sensor
was
fabricated
by
a
CMOS
compatible
process.
The
sensor
size
was
reduced
significantly
to
35
m
×
35
m.
The
sensor
is
sensitive
to
the
vacuum
pressure
range
from
10
−1
Pa
to
10
4
Pa
when
driven
by
a
constant
current
as
small
as
10
A,
and
the
power
consumption
is
low
at
50
W.
©
2019
Published
by
Elsevier
B.V.
1.
Introduction
Vacuum
measurement
has
a
significant
role
in
the
modern
world
[1].
Pirani
vacuum
sensors,
which
are
based
on
the
depen-
dence
of
thermal
conductance
on
vacuum
pressure,
can
cover
a
typical
vacuum
pressure
range
from
10
−1
Pa
to
10
5
Pa
[2].
Micro-
Pirani
vacuum
sensors
have
been
fabricated
using
micromachining
technology
and
they
are
widely
applied
in
vacuum
systems,
such
as
vacuum
chamber
system
and
vacuum
packaging
[3–5].
Micro-Pirani
vacuum
sensors
are
classified
into
four
categories
based
on
the
measurement
principle:
thermistor
type,
surface
acoustic
wave
(SAW)
type,
thermocouple
type,
and
diode
type.
A
thermistor
type
micro-Pirani
vacuum
sensor
based
on
micro
hotplate
is
designed
by
analyzing
various
of
heat
dissipation
approaches,
and
it
achieves
a
dynamic
vacuum
pressure
range
from
8
×
10
−1
Pa
to
9.2
×
10
4
Pa
[6].
SAW
based
micro-Pirani
vacuum
sensor
takes
advantage
of
the
frequency
characteristics
of
materi-
als,
and
a
dynamic
vacuum
pressure
range
between
10
-3
Pa
and
10
5
Pa
has
been
obtained
[7].
A
Thermocouple
consists
of
two
dissimi-
∗
Corresponding
author
at:
Smart
Sensing
Research
and
Development
Centre,
Institute
of
Microelectronics,
Chinese
Academy
of
Sciences,
Beijing
100029,
China.
∗∗
Corresponding
author.
E-mail
addresses:
fujianyu@ime.ac.cn
(J.
Fu),
liuruiwen@ime.ac.cn
(R.
Liu).
lar
electrical
conductors,
and
it
produces
a
temperature-dependent
voltage
as
a
result
of
Seebeck
effect.
The
thermocouple
is
used
in
micro-Pirani
vacuum
sensors,
and
a
wide
measurement
pres-
sure
range
(5
×
10
-3
Pa
to
10
5
Pa)
has
been
realized
[8].
The
diode
based
micro-Pirani
vacuum
sensor
uses
temperature
coefficient
of
diode
for
vacuum
pressure
measurement,
and
a
new
struc-
tural
vacuum
sensor
that
combines
diode
and
micro-air-bridge
has
been
designed
[9].
Among
the
four
categories
micro-Pirani
vacuum
sensors,
the
diode
based
micro-Pirani
vacuum
sensor
gen-
erally
uses
silicon
(Si)
p-n
junctions
and
does
not
require
special
temperature
sensitive
materials,
such
as
platinum
(Pt),
nickel
(Ni),
and
lithium
niobate
(LiNbO
3
),
which
simplifies
the
manufacturing
process.
Moreover,
it
can
be
easily
fabricated
with
a
complemen-
tary
metal
oxide
semiconductor
(CMOS)
compatible
process,
which
allows
convenient
integration
with
other
devices/circuits.
There-
fore,
the
diode
based
micro-Pirani
vacuum
sensor
has
attracted
much
attention.
Considerable
research
effort
has
been
made
to
improve
the
per-
formance
of
diode
based
micro-Pirani
vacuum
sensors.
Klaassen
and
Kovacs
introduced
a
method
that
uses
the
voltage
drop
dif-
ference
between
two
diodes
located
on
the
suspended
structure
and
substrate
to
measure
the
vacuum
pressure.
A
dynamic
vac-
uum
pressure
range
of
more
than
five
decades
(8
×
10
−1
Pa
to
9.2
×
10
4
Pa)
was
obtained
[10].
Kimura
et
al.
developed
a
struc-
https://doi.org/10.1016/j.sna.2019.02.018
0924-4247/©
2019
Published
by
Elsevier
B.V.