From wafer to chip
The wafer-to-chip process is the full journey a piece of silicon takes from a blank polished disc to a packaged, tested microchip, passing through front-end wafer fabrication and back-end assembly and test. Front-end work builds the circuits on the whole wafer inside a fab, while back-end work cuts the wafer into individual chips, packages them and tests them. The Tata Electronics and PSMC fab at Dholera is built for the front-end stage, at a target of up to 50,000 wafers per month on 300 mm wafers.
The wafer as a starting point
A wafer is a thin, round slice of ultra-pure single-crystal silicon, polished to a mirror finish. It is the platform on which many identical chips are built at the same time. Making chips in parallel on one wafer is what makes the economics work, because the fab processes the whole wafer in each step, and every chip on it advances together. The Dholera fab uses 300 mm wafers, the standard size for high-volume manufacturing. A larger wafer holds more chips per pass, so the cost of each processing step is shared across more finished parts, lowering the cost per chip. Before any circuits are built, the wafer is inspected and cleaned to remove any contamination, because everything that follows depends on a flawless starting surface. From this blank disc, the process adds and shapes dozens of layers until a complete circuit exists across the wafer's face.
Front-end fabrication: creating the transistors
The first major phase of front-end work, often called front end of line, builds the transistors themselves directly in and on the silicon. This is where doping creates the regions that switch and carry current, and where the gate structures that control each transistor are formed. It involves repeated cycles of growing or depositing thin films, printing patterns with lithography, etching away unwanted material, implanting dopant atoms and applying heat treatments to settle them. Each transistor is a microscopic switch, and a single chip may contain millions or billions of them, all formed together across the wafer. Precision is extreme, since the features and their alignment are measured in nanometres. This phase defines the chip's process node, which describes how small and dense the transistors are. The Dholera fab targets mature and specialty nodes across a reported 28 to 110 nm range, starting at 55 nm and 90 nm before moving to 28 nm.
Front-end fabrication: wiring it all together
Once the transistors exist, they are useless until they are connected, so the second front-end phase, back end of line, builds the wiring. This is a stack of metal layers, separated by insulating layers, that route signals and power between the transistors and out to the chip's contacts. Modern chips can have many metal layers, each patterned by its own lithography and etch steps and connected to the layers above and below by tiny vertical links called vias. Between each layer the wafer is polished flat by chemical mechanical planarisation so the next layer builds accurately. Confusingly, this wiring phase is still part of the wafer fab, and the term back end of line refers to the later layers on the wafer, not the separate back-end assembly stage. When this is complete, the wafer carries a full grid of finished, interconnected chips, ready for testing.
Wafer test and dicing
Before the wafer is broken up, each chip on it is tested in place. Fine probes touch the chip's contact pads and run electrical checks to see whether the circuit behaves correctly. Chips that fail are recorded so they will not be packaged, which avoids spending money finishing parts that are already known to be defective. The proportion of chips that pass is the wafer's yield, a number the fab works constantly to improve, particularly during the early production ramp when processes are still being tuned. After testing, the wafer is diced, precisely cut along the grid lines into the individual chips, sometimes called die. At this point the front-end work performed in the fab is finished. The good chips move on to the back-end stage, while the wafer as a single object ceases to exist. This is the boundary the Dholera fab operates up to, since it is a front-end fabrication facility.
Back-end assembly and packaging
A bare chip is delicate and its connections are far too small to solder onto a circuit board, so each good chip is packaged. Assembly places the chip into or onto a package that protects it and provides larger, sturdier electrical connections to the outside world. The chip's tiny pads are linked to the package's leads or balls, and the whole assembly is often sealed to guard against moisture and physical damage. Advanced packaging can even combine several chips into one package to boost performance. This back-end work is typically done in a separate facility known as an OSAT, for outsourced semiconductor assembly and test, which has different cleanliness and skill requirements from a front-end fab. A complete national chip ecosystem needs both, which is why Dholera pairs its large front-end fab with a wider cluster, including two additional semiconductor units cleared on 5 May 2026, one in Dholera and one in Surat.
Final test and shipment
After packaging, every chip is tested again, this time as a finished component. Automated test equipment applies signals and measures responses, often across a range of temperatures and voltages, to confirm the chip meets its specification under realistic operating conditions. Some chips are also burned in, run under stress for a period to weed out early failures. Only chips that pass this final test are shipped to customers, who build them into phones, cars, appliances, industrial equipment and countless other products. The entire wafer-to-chip journey, from a blank polished disc to a tested part, can span many weeks and hundreds of steps. Understanding this journey explains why a fab like Dholera's is such a major undertaking, why it depends on reliable power, ultrapure water and skilled staff, and why the region's expressway, planned airport and semi-high-speed rail are being built to serve the industrial city forming around it.
FAQ
What is the difference between front end and back end?
Front-end work, done in a fab, builds the circuits on the whole silicon wafer, creating transistors and wiring. Back-end work, done in an assembly and test facility called an OSAT, cuts the finished wafer into individual chips, packages each one and tests it. Both stages are needed to turn a wafer into shippable chips.
Why are chips made in batches on a wafer?
Processing many chips together on one wafer spreads the cost of each step across hundreds of parts, which is what makes chips affordable. A larger wafer holds more chips, so the Dholera fab uses 300 mm wafers, the high-volume standard, to lower the cost per finished chip.
What does back end of line mean?
Back end of line is a confusing term that still refers to work inside the fab. It means the later stage of wafer processing that builds the metal wiring layers connecting the transistors, as opposed to front end of line, which forms the transistors. It is different from the separate back-end assembly and test stage.
What is wafer dicing?
Dicing is the step where the finished wafer is precisely cut along its grid lines into individual chips. It happens after each chip has been tested in place on the wafer. Once the wafer is diced, the front-end fabrication stage is complete and the good chips move to packaging.
Does the Dholera fab do the whole wafer-to-chip journey?
The Dholera fab handles the front-end stage, building circuits on the wafer through to dicing. The back-end packaging and final testing are done in separate assembly and test facilities. Dholera's cluster strategy pairs the large Tata fab with additional semiconductor units to build a fuller ecosystem.