Method and device for modulating light with semiconductor substrate

• US 8,035,884 B2
• Filed: 10/20/2010
• Issued: 10/11/2011
• Est. Priority Date: 05/05/1994
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Primary Examiner(s): Mack; Ricky
• Assistant Examiner(s): Thomas; Brandi
• Application Number:
  US12/908,846
• Publication Number:
  US 20110038027A1
• Time in Patent Office: 356 Days
• Field of Search: 359290-292, 359/295, 359/298
• US Class Current: 359/291
• 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: G06F 3/1431 using a single graphics controller
• CPC Class Codes: G06F 3/1446 display composed of modules, e.g. video walls
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal. The elements are made by forming a sandwich of two layers and a sacrificial layer between them, the sacrificial layer having a thickness related to the final cavity dimension, and using water or an oxygen based plasma to remove the sacrificial layer.

Claims

1. A method of manufacturing a light modulation device, the method comprising:

providing a semiconductor substrate;

forming a partially transparent fixed first layer on the substrate;

forming a sacrificial layer on the first layer;

forming a reflective second layer on the sacrificial layer, wherein at least a portion of the second layer is spaced apart from the first layer; and

removing the sacrificial layer to form a cavity between the first layer and the second layer, wherein the second layer is configured to move relative to the substrate after the sacrificial layer is removed,

wherein the movement of the second layer relative to the substrate changes the shape of the cavity, and

wherein a spatial configuration of the cavity as defined by the first fixed layer and the reflective second layer determines the quiescent color of light reflected by the light modulation device.

2. The method of claim 1, wherein the semiconductor substrate comprises silicon.

3. The method of claim 1, wherein the second layer is at least partially reflective.

4. The method of claim 1, wherein the second layer is configured to move in response to a voltage applied across the first and second layers.

5. The method of claim 4, wherein the second layer is configured to move in response to a continuously varying voltage.

6. The method of claim 1, wherein at least one of the first and second layers is configured to reflect light depending at least in part on the cavity height.

7. The method of claim 1, further comprising forming interconnects that connect the first and second layers to a controller that is configured to process image data.

8. The method of claim 1, further comprising placing the controller in electrical communication with memory and an image source module.

10. A microelectromechanical (MEMS) device fabricated by the method of claim 1.

11. The method of claim 1, wherein the second layer may be a non-metal.

12. The method of claim 1, wherein the step of providing a semiconductor substrate comprises the step of coating an insulating semiconductor oxide layer onto the substrate.

13. The method of claim 1, wherein the substrate is transparent.

14. The method of claim 1, wherein the semiconductor substrate comprises one of silicon dioxide or silicon nitride.

15. The method of claim 1, further comprising forming posts within the sacrificial layer, wherein the posts are connected to the first layer and to the second layer.

16. The method of claim 1, wherein forming the first layer comprises at least one of ion milling, reactive ion etching, or a buffered oxide etch.

18. The method of claim 1, further comprising depositing

one of an insulating or reflective enhancement layer on the first or the second layer.

19. The method of claim 1, further comprising:

forming at least one additional partially transparent fixed first layer on the substrate;

forming at least one additional sacrificial layer on the additional partially transparent first layer;

forming at least one additional reflective second layer on the additional sacrificial layer, wherein the additional reflective second layer is spaced apart from the additional partially transparent first layer, and the additional reflective second layer is opaque and is configured to move relative to the substrate; and

removing the additional sacrificial layer.

9. The method of 8, wherein the memory and the image source module are in communication with a transceiver.

17. A method of manufacturing a light modulation device, the method comprising:

providing a semiconductor substrate;

forming a partially transparent fixed first layer on the substrate;

forming a sacrificial layer on the first layer;

forming a reflective second layer on the sacrificial layer, wherein at least a portion of the second layer is spaced apart from the first layer; and

removing the sacrificial layer to form a cavity between the first layer and the second layer, wherein the second layer is configured to move relative to the substrate after the sacrificial layer is removed, and wherein the movement of the second layer relative to the substrate changes the shape of the cavity,

wherein at least one of forming a first and second layer comprises codeposition of two materials with different refractive indices simultaneously.