Because of germanium's physical and chemical characteristics, producing ultra-flat germanium wafers usually requires a carefully regulated series of procedures. Precise control of mechanical, chemical, and thermal factors is a must to prepare the material, achieve nanometer-level flatness, prevent oxidation, and maintain wafer integrity throughout all steps.
If not, you can incur several challenges and problems during the manufacturing process. Here are some of them.
During grinding, lapping, or polishing, germanium is more prone to chipping, cracking, or warping because it has a lower hardness and fracture toughness than silicon.
To reduce damage during thinning, careful handling and specialized equipment are required.
The thermal expansion coefficient of germanium is comparatively high (~5.8×10⁶⁻⁶/°C). When processing at high temperatures (such as during annealing or epitaxial growth), this may result in warping and thermal stress.
This complicates thermal matching with other materials, like carriers or substrates.
Compared to silicon, which has been the preferred material for semiconductors for several years, germanium's CMP (chemical mechanical polishing) techniques are less developed. This makes it more challenging to remove and control micro-scratches, dislocations, and particle contamination uniformly.
To avoid introducing defects, highly optimized slurry chemistry and pad materials are a must.
Because germanium can contaminate silicon tools, special processing lines or extensive cleaning between runs are necessary.
Furthermore, some of the etching and polishing chemicals used on germanium are corrosive or incompatible with typical cleanroom conditions.
It becomes more difficult to produce ultra-flat wafers at larger diameters (such as 6" or 8") due to:
Compared to more widely used semiconductor materials like silicon, germanium's material characteristics, chemical behavior, and mechanical limitations make it difficult to create ultra-flat wafers.
Because of this, producing these wafers is far more challenging and costly than producing silicon, even if they are essential for some high-performance applications. If you’d like to learn more about germanium wafer manufacturing in detail, contact Wafer World today!
