HBT vs. MESFET, HEMT, Si BJT...
HBT technology is an indispensable part to
provide high performance integrated circuit power
amplifiers for both
handsets and infrastructure. Extremely high linearity, low voltage
operation,
and high efficiency, along with low cost small size,
with the
simplicity of single polarity power
supplies are among HBT¡¯s many
virtues. These attributes are absolutely essential for hand held
wireless
devices, and they are very hard to achieve with the older technologies
such as Si bipolar
or GaAs MESFET.
-[Message from a professional Industry Consultant]
Extremely High Linearity,
Low Voltage Operation,
and High Efficiency
|
HBT |
Si Bipolar or MESFET |
| Intermod
Efficiency |
15~20dB |
8
dB(Si bipolar) |
|
Supply biasing |
3
to 5 volts |
8
to 15 volts(Si bipolar or GaAs MESFET) |
InGaP HBT vs AlGaAs/GaAs
HBT, SiGe/Si HBT
The biggest merit of InGaP over AlGaAs is greatly longer life time which is about 10 to 20 times
of that of AlGaAs.
| ¡¡ |
AlGaAs
HBT |
InGaP
HBT |
Description |
| Life
Time |
1~2
years |
More
than 20 years |
Difference
by materials
Oxidation problem in Al causes short life.
Less Oxidation & Defect in InGaP |
Etching
Difference |
Complicated
Dry Etching |
Simple
Selective
Wet Etching |
Higher
Yield from InGaP HBT
Etching |
Band
Alignment |
DEc=0.25eV,
DEv=0.13 |
DEc=0.12eV,
DEv=0.38 |
The higher DEv
gets, The less dependency of current gain on the temperature.
Dramatically low current gain when temperature goes high in AlGaAs. |
| The
perfect spatial coincidence of p-n and hetero junc. |
Ga-C
bond
(59 kcal/mol) |
In-C
bond
(47 kcal/mol) |
The practical concern
during material growth. The presence of indium in InGaP inhibits
carbon incorporation and eliminates memory effect associated with
carbon sources. |
- 3 type of HBT process available
Whereas ordinary foundries has one type of process for customers, Knowledge*on has 3
kind of
different processes which were designed to meet different type of
customer¡¯s applications:
1) High Power InGaP HBT process (for GSM, DCS, Base-station etc.)
BVceo>23V, fT=34GHz, fmax=73GHz
GSM PAM requires Higher Bvceo than other
applications. We have High Power process
which of HBT has Bvceo of more than 23V,
compared with 13V of ordinary foundry.
2) High Linearity InGaP HBT process (for CDMA, WCDMA, WLAN etc.)
BVceo>13V, fT=50GHz, fmax=77GHz
High Linearity process we have that
affects to ACPR of CDMA PA.
3) High
Speed InGaP HBT process (for TIA, LD, Optical Comm. Systems,
High speed digital circuits etc.)
BVceo>10V, fT=70GHz, fmax=97GHz
- Key Merits by Stable process and Special Epi design
1. Low Rth
Rth of
Knowledge*on¡¯s HBT is 25% lower than that of other foundries, so we
have reduced Tj
extending device life time as well.
2. Accurate Model(Including Thermal Effect)
We have VBIC model, which is more accurate than simple Gummel-Poon
models that other
foundries are offering.
3. Stabilized Backside via hole process
Backside via hole process is one of the key processes. We succeed stabilization of this
process.
4. Extended HBT life time
Stable process and optimized epi-wafer conditions made the longer life time of our InGaP HBT
possible.
|
