Since electronic devices made of sensitive materials have many advantages and features, these electronic devices are widely used in the field of organic light emitting diode (OLED) displays and adopted for mass production by the related industry in recent years.
The preparation of electronic devices made of sensitive materials of this type requires patterning processes with high precision and throughput to place sensitive materials in specific areas such as the pixels of an organic light emitting diode (OLED) display, but it is difficult to apply the existing industrial patterning techniques together with the sensitive materials.
For instance, the photolithographic patterning technique is one of the most matured and popular techniques used in the industry, but this technique cannot be applied to sensitive materials, since the solvent, etching solution (or gas) used in a photolithographic process must be in a direct contact with the sensitive materials, causing them to be chemically reacted to lose their original properties.
Patterning techniques other than the photolithographic technology, such as an ink-jet printing or deposition with shadow masks, still have problems of applicability, including poor resolution, damage to the sensitive materials, and time-consuming process. As a result of this lack of practical patterning technique, mass production of optoelectronic products containing sensitive materials has been stymied.
Photolithography is a widely used patterning technique throughout the industry because of its major advantages as described below.    (1) The processes and equipments for mass production are well-developed.    (2) The resolution of patterns is high.
Prior arts regarding improving the compatibility of photolithography with sensitive materials include the taco references described as follows:
The first cited reference is U.S. Pat. No. 6,617,186 entitled “Method for producing electroluminescent element” and issued on Sep. 9, 2003 teaches a method of using organic optoelectronic materials directly in a photolithographic patterning process for the preparation of an organic light emitting diode (OLED) display without any measures of protecting the organic optoelectronic materials.
Therefore, the application of this method has a certain level of difficulty, because the solvent and etching solution (or gas) used in the photolithographic process are in a direct contact with the organic optoelectronic materials, and most known organic optoelectronic materials can be chemically reacted to lose their original properties. To the best of our understanding, no manufacturer of the related industry has actually adopted this method for productions so far.
The second cited reference is U.S. Pat. Publication No. 20050032453 entitled “Method for fabricating organic EL element” and published on Feb. 10, 2005.
This invention teaches a method of applying a polymer protecting layer on the organic optoelectronic materials to be patterned, followed by a photolithographic patterning process. After the patterning process is completed, the polymer protecting layer is removed, and then subsequent processing steps are carried out to complete an organic light emitting diode (OLED) display.
Although this method uses a polymer layer to protect organic optoelectronic materials, the polymer layer must be removed by an etching solution or gas after the photolithographic process is completed, and the etching process can seriously damage the organic optoelectronic materials. Therefore, this method is difficult to implement in practical applications. To the best of our understanding, no manufacturer of the related industry has adopted this method for productions so far.