Liquid-resistant air inlet passive device and methods of making same

Abstract

Aspects of the disclosure provide a waterproof packaging technique for fabricating waterproof microphones in mobile devices. A device based on the waterproof packaging technique can include a microelectromechanical system (MEMS) device, a housing enclosing the MEMS device, and a liquid-resistant air inlet passive device (LRAPD) on the housing. The LRAPD can include at least one channel connecting an exterior of the housing with a chamber formed between the housing and the MEMS device. An inside surface of the channel can be coated with a liquid-repellant coating. In some examples, the liquid-repellant coating can be a self-assembled monolayer (SAM) coating.

What is claimed is: 
     
         1 . A method of making a liquid-resistant air inlet passive device (LRAPD) comprising:
 forming a first channel path in a first substrate;   bonding a second substrate to the first substrate; and   forming a second channel path through the second substrate,   wherein one end of the second channel path is connected to the first channel path.   
     
     
         2 . The method of  claim 1  wherein the first substrate is silicon, the second substrate is silicon, or both the first substrate and the second substrate are silicon. 
     
     
         3 . The method of  claim 1  wherein a top surface of the first substrate and a bottom surface of the second substrate are bonded to each other. 
     
     
         4 . The method of  claim 1  wherein the first substrate and the second substrate are thermally bonded. 
     
     
         5 . The method of  claim 1  wherein the first channel path is etched on a top surface of the first substrate. 
     
     
         6 . The method of  claim 1 , further comprising:
 coating a hydrophobic layer on a surface of the first channel path.   
     
     
         7 . The method of  claim 1 , further comprising:
 forming a third channel path through the second substrate positioned such that after bonding the second substrate to the first substrate an end of the third channel path is connected to the first channel path.   
     
     
         8 . The method of  claim 7  wherein the first channel path, the second channel path, and the third channel path forms a channel fluidically connecting a surface of the second substrate and a surface of the first substrate. 
     
     
         9 . The method of  claim 1  wherein the first channel path has a cross-sectional dimension in a range of 2 micrometers to 50 micrometers. 
     
     
         10 . The method of  claim 1  wherein the first channel path has a cross-sectional dimension in a range of 50 micrometers to 500 micrometers. 
     
     
         11 . The method of  claim 1  wherein the first channel path has a first length, the second channel path has a second length, and the first channel path and the second channel path are connected to each other at an angle. 
     
     
         12 . The method of  claim 11  wherein the first length is shorter than the second length. 
     
     
         13 . The method of  claim 11  wherein the angle is substantially 90 degrees. 
     
     
         14 . The method of  claim 11  wherein the angle is less than 90 degrees. 
     
     
         15 . The method of  claim 1 , further comprising:
 forming a cavity in the second substrate that terminates within the second substrate and that is positioned below a portion of the second channel path.   
     
     
         16 . The method of  claim 15 , further comprising:
 positioning absorbent material within the cavity such that the absorbent material does not block the second channel path.   
     
     
         17 . The method of  claim 1  wherein forming the first channel path, forming the second channel path, or forming both the first channel path and the second channel path includes forming a vertical zigzag through the respective substrate. 
     
     
         18 . The method of  claim 17 , further comprising:
 forming a cavity in the respective substrate that terminates within the respective substrate and that is positioned below a portion of the respective channel path.   
     
     
         19 . The method of  claim 1  wherein forming the second channel path includes forming a horizontal zigzag through the second substrate. 
     
     
         20 . The method of  claim 1  wherein forming the second channel path includes forming a plurality of parallel channels.