Senzors utilizes advanced, state-of-the-art silicon micromachining techniques
to manufacture pressure sensors and pressure measuring devices. The technology used is known as
the piezoresistive technology. It consists of four resistors diffused in a single crystal silicon
(also called monolithic silicon) die and forming a Wheatstone bridge.
Manufacturing of basic sensing element (silicon chip)
At the start point stands the silicon wafer. A silicon wafer is a disc of silicon. The disc is created
through a now very common process. First, a bar of silicon is built and is sliced to create each disc.
Once the disc of raw silicon is created, it can be worked on to make any type of electronics. The
process consists in diffusing some atoms of impurities in the raw silicon. Those atoms
integrates inside the silicon structure and modifies the electrical properties of the silicon. This
is the base of any modern electronic.
Computer's microprocessors, microcontrollers, ASICs are all using the same technology.
Compared to microprocessors, pressure sensors are very simple to create.
Four resistors are diffused in the semiconductor to create a Wheatstone bridge.
Once the resistors have been diffused in the semiconductor, the silicon
wafer is micromachined to
create the silicon diaphragm of each silicon die. The thickness of the silicon diaphragm is optimally
selected for each pressure to be measured and determines the pressure range (sensitivity)
of the sensor.
Years ago, silicon
diaphragms were created by drilling in the wafer with tiny diamond-drills. Even though some of
today's manufacturers are still using this technology, it has been proven that drilling in the
silicon creates some constraints leading to some micro-crackings in the silicon diaphragm and
silicon chip in general. Those micro-crackings lead to a less accurate and less reliable sensor.
Additionally, this old method is not very cost-effective since each diaphragm has to be drilled
Today's technology to create the silicon diaphragm is often referred to as the MEMS
(Micro-Electro-Mechanical Systems) technology.
MEMS technology is basically a way to create 3D shapes in a silicon structure, based on chemical
solutions (etching process) and other improved technologies.
All our sensors are manufactured at the wafer level and each wafer contains thousands of sensor dies.
So using this technique, thousands of sensing elements are manufactured at once.