Overview
This lecture explains the manufacturing process of microchips, focusing on how billions of transistors and complex wiring are fabricated with extreme precision in semiconductor factories.
Microchip Structure & Scale
- Modern smartphones contain over 60 microchips with 90 billion transistors in total.
- Each microchip is built on a silicon wafer and can contain up to 26 billion transistors.
- A typical CPU chip includes multiple cores, a memory controller, a graphics processor, and other sections.
- Chips have up to 17 metal wiring layers separated by insulating materials.
- Transistors (FinFETs) are nanoscopic, with sizes around 36x6x52 nanometers and a 57 nanometer pitch.
Microchip Manufacturing Process
- Manufacturing occurs in a "clean room" using 300 mm silicon wafers.
- Wafers undergo ≈1,000 steps over three months to create up to 80 layers in each chip.
- Each layer is constructed by adding, patterning, etching, and depositing materials.
- Photolithography uses photomasks and UV light to transfer patterns onto wafers.
- Deposition tools add materials: metals (like copper), insulators, or silicon.
- Etching and CMP (Chemical Mechanical Planarization) tools remove or level material.
- Ion implantation modifies silicon to create transistor regions (P and N).
- Regular cleaning and inspection ensure defect-free production.
Semiconductor Fabrication Plant Workflow
- Wafers are transported in sealed carriers (FOUPs) between hundreds of machines.
- Each machine performs a specific step in the process, grouped as: mask making, deposition, etching, modification, cleaning, and inspection.
- Fabs can produce millions of CPUs per month using parallel tool rows.
Post-Manufacturing Steps
- Wafers are tested for defective chips; semi-functional chips are categorized or "binned."
- Chips are cut out, mounted on interposers, attached to printed circuit boards, and covered with a heat spreader.
- Final assembly and testing occur before packaging for sale.
Key Terms & Definitions
- Transistor — a basic electronic switch for logic and memory, key to microchips.
- FinFET — a 3D transistor with fin-shaped structure for improved performance.
- Photolithography — process using light and masks to pattern microchip layers.
- Photomask — a stencil used to define the pattern for each chip layer.
- CMP (Chemical Mechanical Planarization) — process to polish wafer surfaces flat.
- FOUP (Front Opening Universal Pod) — container for safe wafer transport.
- Etching — removal of material from the wafer using chemicals or plasma.
- Ion Implanter — tool that bombards silicon with atoms to dope specific regions.
Action Items / Next Steps
- Review processes for creating photomasks, deposition, etching, and ion implantation.
- Watch upcoming videos on transistor physics and chip architecture for deeper understanding.