Efficient Material Modification through Electron Irradiation

In defect engineering, electron irradiation plays an important role in the targeted generation of defects in materials. High-energy electrons (energy: 10 MeV) interact with lattice atoms, inducing vacancies and interstitial defects. At these high energies, displacement cascades can occur, enabling efficient modification of the material structure at significant depths. This approach can be used to tailor material properties in power semiconductors and other advanced materials.

The basic setup of an electron irradiation system consists of three key components: an accelerator, a beam scanning system, and a linear transport system for precise substrate handling. Together, these components provide the basis for controlled and reproducible irradiation processes.

 
The materials to be irradiated are transported at a defined speed through the line-scanned electron beam. The combination of the selected beam current and transport speed determines the applied electron dose. The beam energy is fixed at a monoenergetic 10 MeV. If required, the effective energy can be reduced using scattering plates, although this results in a broader energy distribution. This setup therefore provides both precision and flexibility for a wide range of application requirements.

Substrate handling is designed for efficient electron irradiation. Materials such as silicon wafers are stacked in dedicated holders and subsequently placed in irradiation boxes. Depending on the wafer size, several stacks can be accommodated in a single box. Due to their high energy and penetration depth, the electrons can penetrate the entire substrate stack and irradiate the individual layers. This enables high throughput while providing consistent irradiation throughout the stack, supporting efficient and reliable material modification.

he system’s linear transport system is designed to maximize throughput. Multiple irradiation boxes can be placed on a single tray, which then passes beneath the scanned electron beam at a precisely controlled speed. The combination of transport speed, resulting exposure time, and electron beam current determines the required electron dose applied to the material.

 
For processes requiring higher doses, the substrates can pass through the electron beam multiple times to achieve the desired cumulative dose. To improve irradiation uniformity, substrates can also be processed from both sides in individual dose steps. This flexible approach supports uniform and reproducible material modification.