Pixel via and methods of forming the same

• US 9,134,527 B2
• Filed: 04/04/2011
• Issued: 09/15/2015
• Est. Priority Date: 04/04/2011
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Lee, Hojin, Zhong, Fan, Tao, Yi
• Primary Examiner(s): SAHLE, MAHIDERE S
• Application Number:
  US13/079,599
• Publication Number:
  US 20120249558A1
• Time in Patent Office: 1,625 Days
• Field of Search: 359/290, 359/291, 345/85, 345/108, 438/29, 257/91
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

This disclosure provides systems, methods and apparatuses for pixel vias. In one aspect, a method of forming an electromechanical device having a plurality of pixels includes depositing an electrically conductive black mask on a substrate at each of four corners and along at least one edge region of each pixel, depositing a dielectric layer over the black mask, depositing an optical stack including a stationary electrode over the dielectric layer, and depositing a mechanical layer over the optical stack. The method further includes providing a conductive via in a first pixel of the plurality of pixels, the via disposed in the dielectric layer and electrically connecting the stationary electrode to the black mask, the via disposed in a position along an edge of the first pixel, spaced offset from the edge of the first pixel in a direction towards the center of the first pixel.

Claims

1. A device comprising:

an array of pixels, each pixel having

a substrate;

an electrically conductive black mask disposed on the substrate and masking an optically non-active portion of the pixel at each of four corners of the pixel and along at least one edge region of the pixel;

a dielectric layer disposed over the black mask;

an optical stack disposed over the dielectric layer, the optical stack including a stationary electrode; and

a mechanical layer positioned over the optical stack and defining a cavity between the mechanical layer and the optical stack, the mechanical layer movable through the cavity between an actuated position and a relaxed position, the mechanical layer anchored over the optical stack at each corner of the pixel,

wherein the array of pixels includes a first pixel having a conductive via in the dielectric layer electrically connecting the stationary electrode to the black mask, the conductive via disposed in a position along an edge of the first pixel in an optically non-active area of the first pixel, and wherein the position of the conductive via is spaced offset from the edge of the first pixel in a direction towards the center of the first pixel.

2. The device of claim 1, wherein the array of pixels further includes a second pixel adjacent the first pixel along the edge of the first pixel, wherein the second pixel does not include a via in the dielectric layer for electrically connecting the stationary electrode to the black mask.

3. The device of claim 2, wherein a height of the cavity of the first pixel is greater than a height of the cavity of the second pixel.

4. The device of claim 3, wherein the first pixel is a high gap pixel and the second pixel is a mid gap pixel, and wherein the array of pixels further includes a low gap pixel adjacent the high gap pixel on a side of the high gap pixel opposite the mid gap pixel, and wherein the low gap pixel does not include a via in the dielectric layer for electrically connecting the stationary electrode to the black mask.

5. The device of claim 3, wherein the black mask includes a channel extending from a corner of the pixel to the via along the edge of the first pixel.

6. The device of claim 5, wherein the channel includes a bulge surrounding a footprint of the via.

7. The device of claim 6, wherein a portion of the channel of the black mask including the bulge has a width from an edge of the bulge to the edge of the pixel ranging between about 3 μ

m to about 4.5 μ

m.

8. The device of claim 7, wherein a portion of the first channel of the black mask not including the bulge has a width from an edge of the channel of the black mask to the edge of the pixel ranging between about 2 μ

m to about 3 μ

m.

9. The device of claim 3, wherein a distance from a center of the via to the edge of the first pixel ranges between about 1 μ

m to about 3 μ

m.

10. The device of claim 8, wherein the black mask includes at least one of an optical absorber layer, a dielectric layer, and a conductive bussing layer.

11. The device of claim 10, wherein the via is an opening in the dielectric layer for electrically connecting the conductive bussing layer of the black mask to the stationary electrode of the optical stack.

12. The device of claim 11, further comprising a bias circuit configured to apply a bias voltage, wherein when the bias voltage is applied at least a portion of the mechanical layer is substantially parallel to the substrate.

13. The device of claim 1, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

14. The device of claim 13, further comprising:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

15. The device of claim 14, further comprising an image source module configured to send the image data to the processor.

16. A method of forming a display device having a plurality of pixels, comprising:

depositing an electrically conductive black mask on a substrate, the black mask masking an optically non-active portion of the pixel at each of four corners of each pixel and along at least one edge region of each pixel;

depositing a dielectric layer over the black mask;

depositing an optical stack over the dielectric layer, the optical stack including a stationary electrode;

depositing the mechanical layer over the optical stack, the mechanical layer defining a cavity between the mechanical layer and the optical stack;

anchoring the mechanical layer over the optical stack at each corner of each pixel; and

providing a conductive via in a first pixel of the device, the via disposed in the dielectric layer and electrically connecting the stationary electrode to the black mask, the via disposed in a position along an edge of the first pixel in an optically non-active area of the first pixel, and wherein the position of the conductive via is spaced offset from the edge of the first pixel in a direction towards the center of the first pixel.

17. The method of claim 16, further comprising depositing a sacrificial layer before depositing the mechanical layer and removing the sacrificial layer after depositing the mechanical layer to form the cavity, wherein the sacrificial layer has a thickness selected to define a height of the cavity.

18. The method of claim 17, further comprising forming an anchor hole in the sacrificial layer at each corner of the first pixel, each anchor hole defining where the mechanical layer is anchored over the optical stack at each corner of the first pixel.

19. The method of claim 18, further comprising forming a support post in each anchor hole for supporting the mechanical layer.

20. The method of claim 16, wherein depositing the black mask further includes depositing a channel of the black mask extending from a corner of the pixel to the via along the edge of the first pixel.

21. The method of claim 20, wherein deposing the black mask further includes forming a bulge in the channel surrounding a footprint of the via.

22. The method of claim 16, wherein the first pixel is a high gap pixel, and wherein the plurality of pixels further includes a mid gap pixel adjacent the first pixel along the edge of the first pixel, and wherein the plurality of pixels further includes a low gap pixel adjacent the first pixel opposite the mid gap pixel, wherein the mid gap and low gap pixels do not include a via in the dielectric layer for electrically connecting the stationary electrode to the black mask.

23. The method of claim 16, further comprising forming a reflective layer on a surface of the mechanical layer facing the cavity, the reflective layer and the optical stack forming an interferometric cavity.

24. The method of claim 23, further comprising applying a bias voltage to the optical stack so that at least a portion of the mechanical layer is substantially parallel to the substrate.

25. An electromechanical device comprising:

a plurality of pixels, each pixel including

a substrate;

means for absorbing light disposed on the substrate and masking an optically non-active portion of the pixel at each of four corners of the pixel and along at least one edge region of the pixel;

a dielectric layer disposed over the light absorbing means;

an optical stack disposed over the dielectric layer, the optical stack including a stationary electrode; and

a mechanical layer positioned over the optical stack to define a cavity between the mechanical layer and the optical stack, the mechanical layer movable through the cavity between an actuated position and a relaxed position, the mechanical layer anchored over the optical stack at each corner of the pixel,

wherein the array of pixels includes a first pixel having in the dielectric layer a means for electrically connecting the stationary electrode to the light absorbing means, the connecting means disposed in a position along an edge of the first pixel in an optically non-active area of the first pixel, and wherein the position of the connecting means is spaced offset from the edge of the first pixel in a direction towards the center of the first pixel.

26. The electromechanical device of claim 25, wherein the light absorbing means includes a channel extending from a corner of the pixel to the connecting means along the edge of the first pixel.

27. The electromechanical device of claim 26, wherein the channel includes a bulge surrounding a footprint of the connecting means.

28. The electromechanical device of claim 25, wherein the first pixel is a high gap pixel, and wherein the plurality of pixels further includes a mid gap pixel adjacent the first pixel along the edge of the first pixel, and wherein the plurality of pixels further includes a low gap pixel adjacent the first pixel opposite the mid gap pixel, wherein the mid gap and low gap pixels do not include a means in the dielectric layer for electrically connecting the stationary electrode to the black mask.