Method and apparatus for release-assisted microcontact printing of MEMS

Abstract

The disclosure provides methods and apparatus for release-assisted microcontact printing of MEMS. Specifically, the principles disclosed herein enable patterning diaphragms and conductive membranes on a substrate having articulations of desired shapes and sizes. Such diaphragms deflect under applied pressure or force (e.g., electrostatic, electromagnetic, acoustic, pneumatic, mechanical, etc.) generating a responsive signal. Alternatively, the diaphragm can be made to deflect in response to an external bias to measure the external bias / phenomenon. The disclosed principles enable transferring diaphragms and / or thin membranes without rupturing.

Description

[0001]The application claims the filing-date priority of Provisional Application No. 61 / 528,148 filed Aug. 27, 2011; and application Ser. No. 12 / 636,757, filed Dec. 13, 2009 (which claims priority to Provisional Application No. 61 / 138,014, filed Dec. 16, 2008); and application Ser. No. 12 / 903,149, filed Oct. 12, 2010 (which claims priority to Provisional Application No. 61 / 251,255, filed Oct. 13, 2009). This application is a continuation application of PCT Application PCT / US12 / 52549, filed Aug. 27, 2012. The disclosure of each of these applications is incorporated herein in its entirety.BACKGROUND[0002]1. Field of the Disclosure[0003]The disclosure relates to method and apparatus for microcontact printing of microelectromechanical systems (“MEMS”). More specifically, the disclosure relates to a novel method and apparatus for release-assisted microcontact printing of MEMS.[0004]2. Description of Related Art[0005]MEMS applied over large areas would enable applications in such diverse ...

AI Technical Summary

Benefits of technology

[0011]The disclosure provides methods and apparatus for release-assisted microcontact printing of MEMS. The principles disclosed herein enable patterning diaphragms (interchangeably, membranes) on a substrate having articulations of desired shapes and sizes. Such diaphragms deflect under applied pressure or force (e.g., electrostatic, electromagnetic, acoustic, pneumatic, mechanical, etc.) generating a responsive signal. Alternatively, the diaphragm can be made to deflect in response to an external bias. The disclosed principles enable transferring thin diaphragms without rupturing the diaphragm. The diaphragm can define a single material or a composite of different materials or layers.

[0012]In one embodiment, the disclosure provides a method for forming a MEMS device by contacting a support structure having a diaphragm formed thereon with the MEMS structure. The contact results in transfer of the diaphragm from the support structure onto the MEMS structure. The support structure includes a release layer separating a substrate from the diaphragm. A diaphragm of desired shape and thickness is thus formed over the release layer. The release layer is weakened prior to transferring the diaphragm in order to ease the contact-transfer process. The diaphragm can have varying surface thickness and area. In an exemplary embodiment, the diaphragm had a surface area of less than 0.2 mm2. In another embodiment, the diaphragm surface area was about 0.2-16 mm2. In still another embodiment the diaphragm surface area was larger than 16 mm2. In another exemplary embodiment, the membrane area is as small as 100 nm2 or less.

Problems solved by technology

However, the conventional methods are limited to working within the existing silicon semiconductor-based framework.

Several challenges, including expense, limited size and form-factor, and a restricted materials set, prevent the future realization of new MEMS for applications beyond single chip or single sensor circuits.

Standard processing techniques are particularly restrictive when considering expanding into large area fabrication.

Conventional photolithography methods are also incompatible with printing flexible substrate MEMS and micro-sized sensor arrays.

Such steps require investing in and creating highly specialized mask sets which render conventional photolithography expensive and time and labor intensive.

While the initial investment can be recovered by producing large batches of identical MEMS devices, the conventional methods are cost prohibitive for small batches or for rapid prototype production.

Incorporating mechanical elements made of metal on this scale is difficult because of the residual stresses and patterning challenges of adding metal to the surface.

The surface tension associated with drying solvent during these patterning steps or a later immersion can lead to stiction (or sticking) of the released structure.

Stiction dramatically reduces the production yield.

Although photolithography is suitable for defining high fidelity patterns on planar and rigid substrates, it is difficult to achieve uniform registration and exposure over large areas.

Conventional methods are not suitable for MEMS using organic semiconductors, nanostructured optoelectronic materials which may be fabricated on a flexible substrate.

An alternative approach is to fabricate electronic structures directly on flexible sheets but polymeric substrates offering this flexibility are typically limited to low-temperature processing as they degrade under high temperature processing.

Accordingly, high temperature processing such as thermal growth of oxides and the deposition of polysilicon on a flexible substrate cannot be supported by conventional processes.

However, this approach tends to locate the structures on the surface having the highest strain during bending.

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