SEMICONDUCTOR CHIPS
Semiconductor chip manufacturing capabilities are currently
limited to very few regions in the world. With
supply chain disruptions during the pandemic and recent geopolitical tensions,
many companies and countries, including India,
have realised the importance of investing in chip manufacturing infrastructure.
The
TATA group has partnered with
Taiwan’s Powerchip Semiconductor Manufacturing Corporation (PSMC) to set-up a
300mm wafer fabrication plant in Gujarat. It will roll out its first 28nm chip in 2026.
Two assembly and test plants in
Gujarat and Assam have also been recently approved by the Government of India.
WHAT IS A SEMICONDUCTOR CHIP?
A semiconductor
has properties between a conductor (which conducts electricity) and an insulator (which does not). In its purest form a semiconductor is a very weak conductor of electricity.
CAN ELECTRICAL PROPERTIES OF A SEMICONDUCTOR BE CHANGED?
Its electrical properties
can be changed by adding small amounts of certain substances called ‘dopants’. By taking a pure semiconductor and carefully injecting certain parts with specific dopants, complex circuits can be ‘printed’ on the semiconductor.
The
process is crudely analogous to creating an intricate work of art on a paper or a wall, by using a bunch of stencils and spray paints of different colours. The stencils are called
‘masks’ in the industry and the
paint is analogous to the dopant.
WHAT IS A TRANSISTOR?
The transistor, one of the earliest electronic components to be built using a semiconductor, is
an extremely versatile device.
- In its most popular form it can function as an electronic switch. A typical semiconductor chip can have millions/billions of these interconnected switches that work together to perform various logical and computational operations.
- A transistor can also function as an amplifier (to amplify the weak signal received by your cell phone) and is an integral part of circuits that generate and process high frequency signals (such as those required in wireless communication technologies).
Today
all these different avatars of the transistor are routinely packed into a single semiconductor chip (such as the WiFi chip in your mobile).
WHAT IS FABRICATION?
Technology has progressed at a relentless pace since the semiconductor chip was first conceptualised more than six decades ago.
Newer manufacturing technologies have been introduced regularly.
- The level of miniaturisation of the semiconductor has increased.
- Sticking with the stencil analogy this is mainly due to the stencils being able to etch smaller and more intricate patterns.
- There have been equally impressive gains in the switching capability of the transistors. They are able to switch on-and-off faster (more computations per second) and with lesser power consumption (improved battery life)
UPTO WHAT EXTENT HAS MINIATURISATION BEEN ACHIEVED?
The industry has used labels like
‘45nm’, ‘28nm’ and ‘16nm’ to introduce each new manufacturing technology. These numbers convey the level of miniaturisation that is achievable using a particular technology (so smaller is better).
IS THIS THE DIMENSION OF A TRANSISTOR?
Though not always accurate, you can think of this number as representing the dimensions of single transistor.
IS FABRICATION DONE IN 2D OR 3D?
While traditionally electronic circuits have been laid out flat on the semiconductor, researchers are increasing looking to capitalise on the third dimension (height). As the length and breadth of a transistor switch decreases, increasing its height can help ensure reliable performance.
WHAT IS A WAFER?
A semiconductor chip is
manufactured much like a postage stamp. A sheet of stamps is printed on a piece of paper and then each
individual stamp is cut out. Similarly,
an array (typically 300-400) of chips are printed on a circular piece of semiconductor (called a wafer in industry parlance). This is then diced to create individual chips. A larger wafer size allows more chips to be printed on a single wafer which makes chip production faster and cheaper.
WHAT IS THE SIZE OF A SINGLE WAFER?
Wafer sizes used in the industry have constantly been increasing. The current state of art is
300mm which is approximately 12 inches (this refers to the diameter of the wafer).
STATUS OF SEMICONDUCTOR CHIP MANUFACTURING IN INDIA
India has had a
thriving chip design industry since the 1990s. Due to the magic of
computer aided design it is possible to design a semiconductor chip entirely in software. The process of
specifying the functionality of a chip, translating this functionality to electronic circuits,
validating the circuits,
optimising for
speed,
power consumption and
size, can be done by a team of skilled engineers sitting at their desktops.
The final design is abstracted into a file and sent to a fabrication plant for manufacturing.
India’s foray into semiconductor manufacturing will benefit from the existing ecosystem for chip design which was fuelled by a steady supply of electronics and computer engineers.
CHALLENGES IN SEMICONDUCTOR MANUFACTURING
- High Cost of setting up a plant.
- Dependency on other countries for raw materials for semiconductor manufacturing. (Fabs)
- Supply Chain disruptions.
- Poor Infrastructure & Logistics.
- Lack of skilled manpower.
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