Modern society relies on semiconductor chips. They are the key components of smartphones, computers, medical devices, artificial intelligence systems and many other technologies. To make these chips faster and more energy efficient, the semiconductor industry continuously reduces the size of the structures that are printed onto silicon wafers. Today, the smallest features are only a few tens of nanometres wide, thousands of times smaller than the width of a human hair.
As chip dimensions continue to shrink, a major challenge emerges: how can these tiny structures be inspected quickly, accurately and without damaging them? This process is known as semiconductor metrology. It is essential for ensuring manufacturing quality, improving production yield and reducing material waste. Existing optical inspection methods are fast and non-invasive, but they are fundamentally limited by diffraction: conventional microscopes cannot directly resolve structures much smaller than about half the wavelength of light. As a result, many measurements rely on indirect approaches or large dedicated test structures that are not representative of the actual devices being manufactured.
MICROSEM addresses this challenge by developing a completely new type of optical microscopy that can image semiconductor structures far below the traditional diffraction limit without modifying the sample. The project builds on earlier discoveries made within ERC-funded frontier research, where it was found that a nonlinear optical process called high-harmonic generation (HHG) can be selectively switched on and off with light. This effect makes it possible to confine optical emission to regions much smaller than the size of a conventional laser focus.
Based on this discovery, MICROSEM develops a new imaging approach called Harmonic Deactivation Microscopy (HADES). In HADES, two laser beams are used simultaneously. One beam generates high-harmonic light inside the sample, while a second donut-shaped beam suppresses this emission everywhere except in a very small central region. By scanning this confined light source across the sample, images with a spatial resolution well below the diffraction limit can be obtained. Importantly, this approach is entirely optical, label-free and compatible with semiconductor materials and devices.
The main scientific and technological objective of MICROSEM is to demonstrate optical microscopy with a spatial resolution below the diffraction limit using this new principle. Achieving this goal would represent a major advance because it would provide super-resolution imaging without fluorescent labels, vacuum chambers or electron beams. The microscope is designed to operate in a compact optical setup that can potentially be integrated into existing industrial environments.
A second objective is to demonstrate the usefulness of this technology for semiconductor wafer metrology. The project aims to perform measurements on much smaller targets than currently possible. Such capabilities are increasingly important as semiconductor technologies continue to scale down.
The expected impact of MICROSEM extends beyond a single application. Semiconductor manufacturing is one of the most strategically important industries worldwide and a key pillar of European technological leadership. Improved metrology can contribute to higher production yields, lower manufacturing costs and more sustainable use of materials and energy. The technology developed in MICROSEM could therefore strengthen Europe's position in semiconductor equipment and advanced manufacturing.
In addition, the underlying microscopy concept has applications far beyond semiconductors. Because it combines nanometre spatial resolution with ultrafast nonlinear optical processes, the technology could open new opportunities in materials science, nanotechnology and biomedical imaging. MICROSEM therefore represents not only a new metrology tool, but also a new platform for label-free super-resolution microscopy with broad scientific and industrial relevance.
By translating fundamental discoveries from ERC frontier research into a practical proof of concept, MICROSEM aims to bridge the gap between breakthrough science and real-world technological innovation.
