Out-of-plane spacer defined electrode

Abstract

In one embodiment, a method of forming an out-of-plane electrode includes providing an oxide layer above an upper surface of a device layer, providing a first cap layer portion above an upper surface of the oxide layer, etching a first electrode perimeter defining trench extending through the first cap layer portion and stopping at the oxide layer, depositing a first material portion within the first electrode perimeter defining trench, depositing a second cap layer portion above the first material portion, vapor releasing a portion of the oxide layer, depositing a third cap layer portion above the second cap layer portion, etching a second electrode perimeter defining trench extending through the second cap layer portion and the third cap layer portion, and depositing a second material portion within the second electrode perimeter defining trench, such that a spacer including the first material portion and the second material portion define out-of-plane electrode.

Description

[0001] This application claims priority to US Provisional Application No. 61 / 475,461, filed April 14, 2011. technical field [0002] The present invention relates to wafers and substrates such as are used in microelectromechanical systems (MEMS) devices or semiconductor devices. Background technique [0003] Electrostatic MEMS resonators have become promising technology candidates to replace traditional quartz crystal resonators due to their potential for smaller size, lower power consumption, and low-cost silicon fabrication. However, such devices are usually subject to unacceptably large dynamic impedance (R x )Impact. MEMS devices operating in an out-of-plane direction (ie, a direction perpendicular to the plane defined by the substrate on which the device is formed) have the advantage of having large switching areas on the upper and lower surfaces, thereby reducing dynamic impedance. Consequently, out-of-plane devices have received increasing attention, resulting in si...

AI Technical Summary

Problems solved by technology

[0012] Typically, out-of-plane electrodes are underutilized due to difficulties in reliably fabricating such devices

For example, encapsulation is difficult for out-of-plane devices because out-of-plane electrodes are easily damaged during encapsulation

MEMS resonators that include out-of-plane electrodes are especially complex because such devices require a vacuum packaging process

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