What is the technology of manufacturing semiconductor chips? | Explained

Story so far: Currently, semiconductor chip manufacturing capacity is limited to only a few regions of the world. Supply chain disruptions during the pandemic and recent geopolitical tensions have made many companies and countries, including India, realize the importance of investing in chip manufacturing infrastructure. TATA Group has partnered with Taiwan's Powerchip Semiconductor Manufacturing Corporation (PSMC) to establish a 300mm wafer manufacturing facility in Gujarat. The company plans to roll out its first 28nm chip in 2026. Two assembly and testing plants in Gujarat and Assam were also recently approved by the Indian government.

What is a semiconductor chip? How is it manufactured?

Semiconductors have properties intermediate between conductors (conduct electricity) and insulators (do not conduct electricity). In their purest form, semiconductors are very weak conductors of electricity. However, its electrical properties can be changed by adding small amounts of certain substances called “dopants.” By using pure semiconductors and carefully injecting specific dopants into specific components, complex circuits can be “printed” onto semiconductors.

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The process is almost similar to creating intricate works of art on paper or walls using stencils or spray paint in different colors. Stencils are called “masks” in the industry, and paints are similar to dopants.

What is a transistor?

Transistors are one of the earliest electronic components built using semiconductors and are extremely versatile devices. In its most common form, it functions as an electronic switch. A typical semiconductor chip has millions or billions of these interconnected switches that work together to perform various logical and computational operations.

Transistors also act as amplifiers (amplifying the weak signals received by mobile phones) and are an integral part of circuits that generate and process high-frequency signals (such as those required in wireless communication technology). All the different avatars of the transistor are now routinely packed onto a single semiconductor chip (such as his WiFi chip in a mobile phone).

This transistor demonstrated how to build a single device from a piece of semiconductor. “Printing” multiple devices onto her single semiconductor to create an entire circuit was the next leap. Both of these breakthroughs laid the foundation for the semiconductor revolution and were appropriately recognized by the Nobel Prize (1956 and 2000).

What is processing technology?

Since semiconductor chips were first conceptualized more than 60 years ago, technology has advanced at a relentless pace. New manufacturing techniques are introduced regularly. The level of miniaturization of semiconductors has increased by an order of magnitude. Sticking with the stencil analogy, this is primarily because stencils can etch smaller, more complex patterns. Equally impressive improvements were seen in the switching ability of transistors. Faster on/off switching (more calculations per second) and lower power consumption (longer battery life and less heat dissipation).

The industry has used labels such as “45nm,” “28nm,” and “16nm” to introduce each new manufacturing technology. “nm” is an abbreviation for nanometer, which is a very small unit of length equivalent to one billionth of a meter. These numbers represent the level of miniaturization that can be achieved using a particular technology (lower is better). Although not always accurate, this number can be considered to represent the dimensions of a single transistor. Traditionally, electronic circuits have been laid flat on semiconductors, but researchers are looking to exploit the third dimension (height). As the length and width of the transistor switch decreases, the increased height ensures reliable performance. Stacking entire circuits on top of each other is another way to continue shrinking the size of semiconductor chips.

What is a wafer?

Semiconductor chips are manufactured in the same way as stamps. Stamp sheets are printed on paper and then the individual stamps are cut out. Similarly, an array of chips (typically 300 to 400) is printed onto a circular piece of semiconductor (called a wafer in industry parlance). This is then diced to create individual chips. Increasing wafer size allows more chips to be printed on a single wafer, making chip production faster and cheaper. The size of wafers used in the industry is continuously increasing. The current state of the art is 300mm, or about 12 inches (this refers to the diameter of the wafer). Efforts continue to move the wafer size to 450mm. Although moving to larger wafer sizes involves technical challenges and capital investment, it has proven to be economical in the long run.

Once the wafer is diced into chips, the individual chips must be packaged with a protective cover. Thin wires must be routed from the device to the package border. Some of these wires provide power, while others are used to input and read signals and data. Chips must also undergo tests such as functional verification and stress testing (exposing the chip to high temperatures and voltages) to ensure reliability over its lifetime. All this takes place in our assembly and testing factory.

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What is the semiconductor ecosystem like in India?

India has had a thriving chip design industry since the 1990s. Through the magic of computer-aided design, it is possible to design semiconductor chips entirely in software. The process of specifying a chip's functionality, translating this functionality into an electronic circuit, validating the circuit, and optimizing it for speed, power consumption, and size can be performed by a team of skilled engineers sitting at a desktop. The final design is abstracted into a file and sent to a manufacturing facility for manufacturing. This is similar to designing an entire graphic novel on a laptop and then sending the PDF to a publisher for printing.

India's foray into semiconductor manufacturing will benefit from an existing ecosystem of chip designs supported by a steady supply of electronics and computer engineers. Semiconductor manufacturing is an inherently multidisciplinary endeavor, potentially providing opportunities for a wide range of professionals, including process and control engineers, data scientists, materials scientists, physicists, and chemical engineers, to meaningfully contribute to the industry. there is.

The author is affiliated with Texas Instruments