|United States Of America||Issued Patent||7,994,029||08/09/2011||2008-139|
In order to improve the device characteristic of optoelectronic products, such as solar cells and flat-panel displays, the amorphous material such as the transparent conductive oxide has to be transferred by thermal treatment into crystalline material so as to reduce the resistivity and enhance the transparency. Generally, six runs of process (five for pattern transfer and one for thermal treatment) are required to complete the crystalline pattern. To overcome the problems due to the multi-step and high-cost process, laser machining is used in some processing steps to ablate the undesired portion of the thin films. However, convention long pulse laser results in thermal effects to cause elevated ridges on the edge and defects in the layers below.
US Berkeley researchers have discovered a method for patterning crystalline indium tin oxide using a femtosecond laser which overcome the above-mentioned problems by using a focusing device with the laser to heat up the amorphous indium tin oxide (ITO).