Chips are making the world smarter. Nowadays, smart vehicles are able to sense dynamic surroundings to avoid bumping into obstacles, smart cameras can capture ultra-HD photos while offering a real-time sharing function, and smart homes are equipped with automatic lights and robot vacuums among other intelligent devices. Chips have therefore become a core technology for human beings. If you are curious about what goes on behind the scenes of the design and manufacturing of a chip that carries tens of millions or even tens of billions of transistors, take a look at the following video to find out more.
The process of chip production can be divided into chip design and chip manufacturing.
Chip design specifies the usage, specifications, and performance of the chip. Chip design involves specifications, system design, front-end design, and back-end design.
1. Specifications. During the early stage of chip design, engineers analyze chip requirements and define product specifications to decide on the overall design. The specifications include the cost, computing power, power consumption, connection modes, and security compliance.
2. System design. Based on the specifications, the system design determines the chip architecture, service modules, and power supplies, including the CPU, GPU, NPU, RAM, connections, and interfaces. In addition, system interaction, functions, performance, maintainability, and testability are also key elements that are taken into consideration.
3. Front-end design. In this phase, engineers design circuits for each module based on the system design. To set up circuits, a dedicated hardware description language (Verilog or VHDL) is used to generate the register transfer level (RTL) code. After that, simulation verification is repeated to ensure that the code design is correct and complies with standards. RTL code is then transformed into a gate-level netlist by a logic synthesis tool to ensure that target parameters such as area and timing of the circuits meet the standard. Static timing analysis comes after logic synthesis to check whether a particular circuit violates the preset timing limit by using a timing model. The design process is iterative. If any step fails, engineers need to go back to the previous steps or even start all over again.
4. Back-end design. This phase is to design the floor plan and place and route of the circuits based on the netlist within the specified wafer area. The next step is to verify the function and timing of the physical layout, such as the design rule check and layout versus schematic (LVS). The back-end design is also an iterative process. The ultimate goal is to generate the geometry data standard (GDS) for chip production.
Chip manufacturing is the process whereby sand is turned into chips. Sand is rich in silicon dioxide, from which silicon is extracted after heating, purification, and filtration. It is then cast into block monocrystalline silicon with high purity, which is called crystal ingots. Crystal ingots are then cut into slices, also known as wafers, with a thickness of 0.5 mm to 1.5 mm as required.
After being polished and strictly screened, wafers are put into front end of line (FEOL). This stage focuses on the manufacture of integrated transistors achieved by photolithography, thin-film deposition, etching, cleaning, injection, and other processes.
Back end of line (BEOL) starts from the deposition of undoped silicon oxide, or silicon glass. The follow-up steps are filling vias with tungsten, and then connecting transistors by using electrical traces. After that, the wafers are diced into dies, which are then packaged for dust prevention. This is a simplified description of chip design and manufacturing.
In reality, the production of microprocessors actually involves thousands of processes, which last for several weeks. Although small in size, chips have infiltrated every aspect of our lives, changing how we communicate, how we travel, and how we manage our cities.