Batch Transfer Printing of Small-Size Silicon Nano-Films with Flat Stamp.

Wenping Cao,Changde He,Guochang Liu,Renxin Wang,Wendong Zhang,Jinwei Miao,Yuhua Yang,Guojun Zhang,Jiangong Cui

doi:10.3390/mi12101255

Abstract

Silicon nano-film is essential for the rapidly developing fields of nanoscience and flexible electronics, due to its compatibility with the CMOS process. Viscoelastic PDMS material can adhere to Si, SiO2, and other materials via intermolecular force and play a key role in flexible electronic devices. Researchers have studied many methods of transfer printing silicon nano-films based on PDMS stamps with pyramid microstructures. However, only large-scale transfer printing processes of silicon nano-films with line widths above 20 have been reported, mainly because the distribution of pyramid microstructures proposes a request on the size of silicon nano-films. In this paper, The PDMS base to the curing agent ratio affects the adhesion to silicon and enables the transfer, without the need for secondary alignment photolithography, and a flat stamp has been used during the transfer printing, with no requirement for the attaching pressure and detaching speed. Transfer printing of 20 wide structures has been realized, while the success rate is 99.3%. The progress is promising in the development of miniature flexible sensors, especially flexible hydrophone.

Highlights

Flexible electronics are formed by organic or inorganic electronic devices, combined with the flexible substrate in a certain way
This paper proposes a method of transfer printing the top silicon structure of the SOI wafer to the PDMS substrate through the difference of adhesion between the PDMS stamp and the receiving substrate to the silicon nano-films
This paper proposes a method that uses the buried oxide layer of the SOI wafer as the sacrificial layer, the photoresist fixes and supports the top silicon nano-films structure

Summary

Introduction

Flexible electronics are formed by organic or inorganic electronic devices, combined with the flexible substrate in a certain way. Flexible electronics can be used more widely, operate in almost all types of environments, and adapt to the deformation of the equipment to some extent [9]. In the field of flexible electronics, organic materials have been widely studied because of their high deformability and their capacity to perform certain sensitive functions. Due to the different test principles, different structures and materials of the sensing units, and flexible substrates used, incompatibility often occurs, which causes a series of problems—such as complex structure, complicated preparation process, and poor reliability. The brittleness and low ductility of inorganic materials seriously restrict the application in the field of flexible electronics

Methods

Discussion

Conclusion