Photolithography: The Essential Foundation of Microchip Fabrication

This lecture provides an in-depth study of Photolithography (or Optical Lithography), the single most critical patterning step in the fabrication of all modern Integrated Circuits (ICs).

We will explore the entire lithographic process sequence: from wafer preparation and the application of light-sensitive photoresist, through high-resolution exposure using photomasks and steppers/scanners, to the subsequent development that defines the geometric patterns on the chip.

Key topics include the principles of light chemistry, factors affecting resolution and Critical Dimension (CD) control, and the challenges driving the industry toward advanced techniques like Extreme Ultraviolet (EUV) Lithography. Understanding photolithography is fundamental to comprehending how trillions of nanoscopic transistors are precisely created to form a microchip.

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1. PHOTOLITHOGRAPHY Dr. G.S.Virdi Ex-Chief Scientist CSIR-CEERI Pilani

2. LITHOGRAPHY Lithography comes from the Greek word “ lithos” which means stones, and “ graphia” , meaning to write. It means quite literally writing on stones. The process of producing patterns on semiconductor crystals for use as integrated circuits. In semiconductor lithography is called as PHOTOLITHOGRAPHY.

3. PHOTOLITHOGRAPHY Photo - litho - graphy can be light-silicon wafer-printing. Photolithography is a printing method in which light plays an essential role. It can produce very small patterns which may be down to few tons of nanometers in size. It provides precise control of the shape and size of the objects.

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