Anisotropic Etching of Glass
Isotropic Wet Etching of Glass
Glass is an amorphous material with perfectly isotropic material properties. As such, wet etching of glass is inherently isotropic, which means if a glass surface is exposed to a chemical attack, material removal starts from this point on the surface and proceeds with the same speed in every spatial direction.
This is of particular interest when wet etching is applied to generate microfeatures on glass surfaces. In such cases, a micropatterned mask is used to protect parts of the glass surface from being attacked by the etchant. Due to the isotropic etching characteristics, all features of the mask are transferred to the glass surface and the features grow in width at the same rate as they grow in depth.
Consequently, only shallow microfeatures are possible. Shallow features have aspect ratios (the aspect ratio is the ratio between the depth and the width of the feature) of less than one.
Laser Induced Deep Etching Enables Deep Micro-features in Glass
LIDE technology enables anisotropic wet etching of standard glasses by upstream laser processing and particularly deep features with aspect ratios of up 1:50.