What Is a Photomask?
A photomask is a high-precision quartz or glass plate with intricate patterns used in semiconductor fabrication. It serves as a template for transferring circuit designs onto wafers during the photolithography process.
How Are Photomasks Used in Semiconductor Fabrication?
- Pattern Transfer: Light is projected through the photomask to transfer its pattern onto a photoresist-coated wafer.
- Exposure and Development: Exposed photoresist reacts chemically, revealing the desired pattern.
- Etching and Deposition: The pattern acts as a stencil for etching or depositing materials.
- Multi-Layer Fabrication: Multiple photomasks are used for different device layers.
Applications of Photomasks
- Integrated Circuits (ICs): Used in fabricating transistors and interconnects for microprocessors and memory chips.
- MEMS Devices: Essential for sensors and actuators.
- Photonic Devices: Creates patterns for optical waveguides and lasers.
- Displays: Used in LCD and OLED production.
Importance of Photomasks
- Precision: Enables nanometer-scale accuracy in device patterning.
- Scalability: Allows mass production of identical devices.
- Advanced Technology: Critical for achieving smaller feature sizes in modern chips.