Adhesive-Free and Selective Thin Film Transfer for Heterogeneous Integration
Publication Date: 2016-Mar-23
The IP.com Prior Art Database
Disclosed is a method of leveraging stiction to achieve adhesive-free film transfer. The method is for heterogeneous integration where a film or a stack of films is transferred to the target substrate and sticks to the target surface with van der Waals forces.
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-Free and Selective Thin Film Transfer for Heterogeneous Integration
Free and Selective Thin Film Transfer for Heterogeneous Integration
Heterogeneous integration enables complex and optimized material combination on a single substrate. Examples include integrating piezoelectric material onto Complementary Metal-Oxide Semiconductor (CMOS) Back-End-of-Line BEOL and integrating Micro-Electromechanical Systems (MEMS) structures micro-machined from single crystal silicon to a flexible substrate. Such heterogeneous integration is typically done with various bonding methods involving a bonding agent. Bonding agents can be polymer adhesive, oxide, metal, solder, etc.
The need for such a bonding agent posts challenges including the need for extra steps in applications of bonding agents, the need for extra thickness with the bonding agent, compatibility with following steps, and stability of the material. This is especially a concern with polymer adhesives. In addition, when dielectric bonding agents are used, such as polymer or oxide, extra processing steps are required to make the electric contact.
Release is a step in the MEMS process where sacrificial material is removed via etchant to create suspended structures. Stiction related to release in a water-based solution (e.g., dilute Hydrogen Fluoride (DHF) is a common and well-known problem in fabricating MEMEs structures. If the restoring force is not large enough to overcome the stiction force, then the bea...