Custom Crystal Growth

Manufacturing custom silicon and germanium boules involves several steps to produce high-quality crystals with tailored properties.

• In the Czochralski method, to initiate nucleation, a seed crystal (or small crystal) is immersed in molten silicon or germanium in a high-temperature environment and is slowly pulled while rotating, allowing a single crystal to grow along the direction of the pull. The crystal grows in a cylindrical shape called a boule.
  
• We carefully control several factors that affect the growth rate of crystals, such as the temperature, pulling speed, and other parameters in the crystallization process to achieve desired crystal quality and orientation while minimizing crystal defects and ensuring uniform crystal surfaces. For example, higher supersaturation levels lead to faster growth rates, but excessive supersaturation can result in increased defects.

• Diffusion plays a crucial role in crystal growth kinetics – it governs the movement of atoms from the melt phase to the crystal surface and their incorporation into the lattice. The diffusion of impurities also affects the crystal’s electrical properties. Considering thermodynamic factors is also important in the crystal growth process, as they govern the stability of a crystal structure which in turn can affect its mechanical, electrical, and optical properties.
• Quality control measures are implemented throughout the custom growth process to control the morphology of the finished crystals. The crystal boules are subjected to various measurements and testing to verify their properties and quality, such as X-Ray Crystallography to test crystal orientation with tolerances to +/- 15 Minutes. Lattice Materials has invested heavily in leading-edge metrology capabilities.