Fabrication of multi-stacks rigid island platform via initiated chemical vapor deposition and its application

Abstract

Stretchable electronics, which is considered to next-generation form factor, attract a lot of interest and it is applied to various research fields. Currently, high-performance stretchable TFTs based on oxide semiconductors are developed. In previous studies, oxide TFTs, which are too brittle to maintain performance under strain, is fabricated on a rigid platform designed for strain relief, such as rigid island substrate and rigid platform embedded substrate. Although strain relief substrates using rigid platform were utilized for many applications, high process complexity due to vulnerable substrate platform, poor adhesion between elastomers and rigid platform, low bendability due to the rigid platform, and bulky design are still problems. Here, the modulus graded multi-stacks rigid island substrated is designed by iCVD process. By using iCVD process, modulus graded rigid platform can be fabricated in a thin manner achieving high bendability and low bulkiness. Also, synthesized polymer film, pGAA2, which is located at the top of the modulus graded rigid platform, exhibits thermal and chemical stability, and is suitable for carrying out a harsh process. Developed modulus graded rigid island substrate is applied to fabricate stretchable oxide TFTs. Directly deposited a-IGZO based TFTs show high performance ($I_{on}/I_{off} > 10^{7}, μ_{sat}>15 [cm^{2}/Ns], V_{th} ~ 0V), and maintain functionality even under the 20% of elongation, 2.5R of bending. The substrate platform developed through this research is expected to be applied to various stretchable devices in the future.