The quality of the sapphire substrate has a great influence on the subsequent growth of the GaN epitaxial layer, the performance and yield of the blue diode production. This not only requires excellent substrate preparation technology, but also a very important link in the detection technology of substrate quality.
The bending (BOW) refers to the distance between the center point of the neutral plane of the free unclamped wafer and the reference plane of the neutral plane. The median plane reference plane is a plane determined by three equidistant points on the designated diameter circle that is smaller than the nominal diameter of the wafer.
When measuring the bending of the sapphire substrate, under the non-adsorption state, the virtual plane calculated by the least square method is used as the reference plane for measurement. The BOW value is the sum of the absolute value of the workpiece center measurement value (measurement surface) and the absolute value of the measurement value with the largest absolute value, which is different from the center value sign. The symbol is the symbol of the center measurement value.
Regarding the BOW value standard, there are specific provisions in the SEMI related standards. However, with the development of sapphire substrate patterning (PSS), epitaxial manufacturers have higher requirements for the curvature of sapphire substrates, and the industry has reached a higher consensus on this index.
Cryscore Optoelectronic Limited is committed to the research and development , manufacturing and sales of higher-quality sapphire substrates. It has core equipment and realizes the core process of combining equipment and materials. It has the ability to produce high-quality sapphire substrates, and the BOW value of the produced sapphire substrates is better than Industry level.