Producing the Modern CPU
By: Ali Anwar
Computers are everywhere in the modern world. What powers them? A
modern CPU can contain over 100 billion transistors, all packed together on a
slice of silicon no thicker than a fingernail. What is the process for making these
marvels of engineering? As an overview, the process includes design, fabrication,
testing, and assembly. Let’s explore each stage of production.
The beginning of a CPU’s manufacturing process starts with designing its
layout. Engineers need to plan what type of architecture the CPU will use as well
as its functionality and use case. They must plan how many cores (processors),
cache, and other elements to put in this model. Next, engineers will use
computer-aided design (CAD) tools and electronic design automation (EDA)
software to model its layout and circuitry. CAD and EDA help engineers design
these immensely complex devices with performance and efficiency in mind.
Once the design is finalized, fabrication begins. Manufacturing CPUs is an
incredibly precise process. This can only be done by a very select few companies
with incredibly sharp machine manufacturing and procedures. Modern CPUs
have become so small that entirely new manufacturing techniques are required
to fabricate them. CPUs are produced using photolithography. Photolithography,
in short, uses light to etch an image onto a thin silicon wafer, machined to a very
high standard. The standards of manufacturing are so incredibly tight, one single
speck of dust on the silicon wafer deems it unusable. This silicon wafer is coated
in photoresist, a material that responds to light and washes away, leaving a
tracing of the image etched onto the silicon wafer. This image contains a
microscopic blueprint of the chip’s circuit design. Multiple images are used since
there are multiple layers built up onto each other. This layering process is
repeated until the microchip fabrication is complete. You can think of it as a 3D
printer, building up layers and layers until completion.
Another key component in the production of the CPU is the printed circuit
board (PCB). This is what the silicon chip rests on. The CPU’s PCB typically
consists of multiple layers of green fiberglass with conductive copper traces that
connect the large components of a CPU including the silicon microchip, resistors,
capacitors, memory chips, ports, etc. The PCB allows all of the CPU components
to interact with each other. Engineers use software to design an efficient plan for
the PCB and where to place each component. Similar to other components, PCBs
are built upon layers and stacking methods. PCBs, just like microchips, use
photolithography to print the circuitry. After photolithography, the PCB board is
covered in a solution and unwanted copper is etched away. What you end up with
is a PCB with copper traces and the circuitry. A thin protective layer is applied
over the copper traces to protect against corrosion and prevent accidental
contact.
Testing and assembly is the next step. Electrical and quality tests are
performed to catch any defects or other issues before the board is assembled.
Any microchips with issues are “binned”. This means the faulty cores are turned
off and the chip is used in lower tier CPUs that contain fewer cores and less
performance than a high tier chip. After thorough testing, the microchip and
other components are carefully soldered onto the PCB, forming an electrical and
mechanical bond between all the components. Thousands of electrical pins make
contact and connect the components of the CPU with the motherboard of the
computer. An integrated heat spreader is placed at the top of the CPU to
maintain temperature. Together, these parts form a CPU.
Today, CPUs power nearly every aspect of modern life: cars, phones,
computers, cameras, kitchen appliances, and even toothbrushes. The process of
producing them is incredibly delicate and requires pinpoint accuracy with
nanometer precision. It combines several various parts that all fit together to
form one of the most technologically advanced creations ever made by
humankind.
Sources
●​ How CPUs Are Made? CPU Manufacturing Process Explained
●​ How Are CPUs Actually Made?
●​ What Is a CPU Core? A Basic Definition | Tom's Hardware
●​ The PCB Manufacturing Process Explained - Microchip USA - PCBs