Development of Si-chips with anisotropic rough surface

Abstract

The areal roughness of a surface can be described by a number of parameters including the texture aspect ratio S tr as the degree of isotropy or anisotropy. For the comparison of roughness with optical instruments silicon reference samples with the anisotropical roughness of S a ≈ 280 nm and 4 different values of the texture aspect ratio S tr (0.9; 0.75; 0.65; 0.50) have been developed. The anisotropy is produced by scratching of grooves on the lapped surface using a suitable stylus. Different distances of grooves in different regions of the chip result in different values of S tr representing distinct anisotropies. Special marks etched in the silicon chip allow the positioning of the measurement fields with micrometer precision. Measurements performed with a confocal microscope have shown that the grooves do not noticeably influence the parameters of height and the hybrid parameters of roughness. The process of manufacturing by lapping followed by scratching guaranties a good reproducibility of the surface attested by comparison of two chips. Consequently the described reference sample can play the role of a material measure.