Optical lithography from ZEISS SMT

Optical lithography projects the pattern of a photomask onto a light-sensitive photoresist layer on a silicon wafer. This process makes it possible to manufacture microchips with ever finer structures. ZEISS SMT supplies the highly precise illumination systems and projection optics required for this process. Optical lithography is at the heart of modern semiconductor manufacturing and enables the production of logic and memory chips.

The photolithography process begins with a silicon wafer coated with a light-sensitive photoresist. In the wafer stepper, ZEISS optics project the pattern of a photomask onto the wafer. The light changes the chemistry of the resist, allowing the exposed areas to be removed later through etching. This reveals the structure of the conductor paths on the wafer, and the remaining photoresist is removed. After many additional processing steps, the wafer contains several thousand microchips, which are separated using micrometer-thin saw blades. This multi-step process forms the basis for manufacturing modern CPUs, GPUs, and memory chips.

The wavelength of the light used is crucial for resolution and therefore for the fineness of chip structures. The shorter the wavelength, the smaller the structures that can be imaged – a principle based on Abbe’s theory of resolution. DUV technology uses light with wavelengths of 365, 248, and 193 nanometers; EUV technology uses 13.5 nanometers. ZEISS SMT develops highly precise optical systems and components that can control these extremely short wavelengths, enabling increasingly powerful microchips.

DUV technology (Deep Ultraviolet) uses light with wavelengths of 365, 248, and 193 nanometers and has advanced the semiconductor industry for decades. EUV technology (Extreme Ultraviolet) works with an extremely short wavelength of 13.5 nanometers, enabling the production of even smaller and more powerful chip structures. While DUV relies on lenses, EUV lithography uses mirror systems. ZEISS SMT supplies optics for both technologies.

ZEISS and ASML are already developing High-NA EUV systems (High Numerical Aperture) that take lithography capabilities even further. While established EUV lithography operates with an NA of 0.33, High-NA EUV reaches 0.55. This allows the optical system to capture light from a wider range of angles and image finer details. High-NA EUV technology enables around three times more structures on the same area and supports the semiconductor industry in continuing Moore’s Law beyond 2030.

Gordon Moore predicted that the number of components — or transistors – on an integrated circuit would roughly double every two years. This development is enabled primarily by ever smaller chip structures. This exponential trend drives technological progress and makes microchips continuously more powerful and more energy-efficient. Moore’s Law has become a guiding principle for the entire semiconductor industry and continues to motivate innovation in optical lithography. Over the past 50 years, ZEISS SMT has made a significant contribution to extending this principle through increasingly precise lithography optics.