Combined thin film pinhole and semiconductor photodetectors

• US 5,536,964 A
• Filed: 09/30/1994
• Issued: 07/16/1996
• Est. Priority Date: 09/30/1994
• Status: Expired due to Fees

• Current Assignee: Albert K. Hu, Evan D.H. Green, Tario M. Haniff
• Original Assignee: Albert K. Hu, Evan D.H. Green, Tario M. Haniff
• Inventors: Green, Evan D. H., Hu, Albert K., Haniff, Tario M.
• Primary Examiner(s): MINTEL, WILLIAM A
• Application Number:
  US08/315,835
• Time in Patent Office: 655 Days
• Field of Search: 257/447, 257/448, 257/443, 257/466, 257/432, 257/433, 257/434, 250/237 R, 250/208.6, 250/206.1
• US Class Current: 257/432
• CPC Class Codes: H01L 27/1443 with at least one potential jump or surface barrier
• CPC Class Codes: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 31/02024 Position sensitive and lateral effect photodetectors; Quadrant photodiodes
• CPC Class Codes: Y10S 438/928 Front and rear surface processing
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

A thin-film semiconductor pinhole component with monolithically integrated position-sensing photodetectors is herein referred to as a Position Sensitive Pinhole (PSP). Another embodiment is also discussed where a PSP is integrated onto a platform with controllable motion and is herein referred to as a Movable Position Sensitive Pinhole (MPSP). A third embodiment describes the MPSP with capacitive, electrostatic actuation incorporated into the device to achieve controlled motion, herein referred to as a Capacitively Actuated Movable Position Sensitive Pinhole (CAMPSP). Each of those embodiments of the present invention are discussed, as are their method of manufacture and use in a laser environment as a spatial filter.

Claims

1. A combined thin film pinhole and semiconductor photodetector array for use with an external electrical biasing source and current measurement devices in optical applications, said combined thin film pinhole and semiconductor photodetector array comprising:

a semiconductor substrate of a selected material defining a pinhole having a perimeter of a selected size and shape therethrough said substrate; and

said substrate including thereon an array of a selected number of photodiodes formed thereon at selected locations around the perimeter of said pinhole.

3. The combined pinhole and semiconductor photodetector array as in claim 1 wherein said semiconductor photodetector array can determine spatial relationships between said pinhole and illumination from a remote light source incident on said semiconductor photodetector array.

4. The combined pinhole and semiconductor photodetector array of claim 1 wherein:

said pinhole perimeter shape is selected to be circular; and

said semiconductor substrate is selected to be sufficiently thin to allow substantial transmission of light through the pinhole.

5. The combined pinhole and semiconductor photodetector array of claim 4 wherein said pinhole is suitable for optical spatial filtering.

6. The combined pinhole and semiconductor photodetector array of claim 1 further includes an electronic means for biasing, current measurement or voltage measurement of the elements of said semiconductor photodetector array on said semiconductor substrate.

7. The combined pinhole and semiconductor photodetector array of claim 6 wherein said thin film pinhole can be used without external electrical means for biasing, current measurement or voltage measurement.

8. The combined pinhole and semiconductor photodetector array of claim 1 further includes a predetermined number of semiconductor spring elements which attach the portion of said semiconductor substrate surrounding said pinhole to the remainder of the substrate.

9. The combined pinhole and semiconductor photodetector array of claim 8 wherein said spring elements allow relative motion between the portion of said semiconductor substrate surrounding said pinhole and the remainder of the substrate by compression, extension, or torsion of said spring elements.

10. The combined thin film pinhole and semiconductor photodetector array of claim 1 further includes:

a predetermined number of semiconductor spring elements which attach the portion of said semiconductor substrate surrounding said pinhole to the remainder of the substrate; and

a predetermined number of electrical capacitor structures, each capacitor structure having;

a predetermined number of electrically accessible elements on the portion of said semiconductor substrate surrounding said pinhole; and

a predetermined number of electrically accessible elements on the remainder of the substrate, separate from said electrically accessible elements on said portion of said semiconductor substrate surrounding said pinhole.

11. The combined thin film pinhole and semiconductor photodetector array of claim 10 wherein said electrical capacitor structures provides relative motions between the portion of the substrate containing said pinhole and the remainder of the substrate by providing force to cause compression, extension, or torsion of said spring elements.

2. An optical system comprising:

a combined thin film pinhole and semiconductor photodetector array having;

a semiconductor substrate of a selected material defining a pinhole having a perimeter of a selected size and shape therethrough said substrate; and

said substrate including thereon an array of a selected number of photodiodes formed thereon at selected locations around the perimeter of said pinhole; and

an external electrical biasing source connected to said photodiodes of said semiconductor substrate to back-bias each of said photodiodes; and

a plurality of current measurement devices connected to said photodiodes of said semiconductor substrate to detect variations in individual currents as a result of variations in illumination of each of said photodiodes.

12. An optical system comprising:

a combined thin film pinhole and semiconductor photodetector array having;

a semiconductor substrate of a selected material having a pinhole of predetermined size and shape through said semiconductor substrate; and

an array of a predetermined number of semiconductor photodetectors formed on said semiconductor substrate at selected locations around the perimeter of said pinhole; and

an electronic means for biasing, current measurement or voltage measurement of the elements of said semiconductor photodetector capable of detecting variations in the light induced current or voltage resulting from variations in illumination of each element of said photodetector array.

13. The optical system of claim 12 wherein said optical system functions as both an optical element and provides an alignment signal of said optical element.

14. The optical system of claim 12 further includes an electrically controlled visual display means for displaying information describing the variations in illumination of each element of said semiconductor photodetector array.

15. The optical system of claim 14 wherein said optical system provides visual feedback to an operator in order to enable said operator to determine the spatial relationship between said pinhole and illumination from a remote light source incident on said semiconductor photodetector array.

16. The optical system of claim 12 further including:

a mechanical mounting means for holding said combined thin film pinhole and semiconductor photodetector array while allowing movement of the thin film pinhole relative to a fixed reference point; and

an electrical computation system means for controlling the motion of said mechanical mounting means in response to said detected variations in said current or voltage resulting from said variations in illumination of each element of said photodetector array.

17. The optical system of claim 16 wherein said optical system comprises a means for causing said thin film pinhole and incident illumination from a remote light source to be brought into coincidence.

18. A position sensing photodetector array comprising a semiconductor substrate including multiple photodiode elements, with each of said multiple photodiode elements:

sharing a common anode or a common cathode with all other elements of said photodetector array; and

having an anode or a cathode which is separate from all other elements of said photodetector array; and

having a separate connection to said common anode or common cathode at a position unique to each of said elements of said semiconductor photodetector array.

19. The position sensing photodetector array of claim 18 wherein said position sensing photodetector array provides an electrically readable means for determining the spatial relationship between said multiple photodiode elements and incident illumination from a remote light source.

20. The position sensing photodetector array of claim 18 wherein said position sensing photodetector array can be switched between split cell and continuous cell operation conditions by selection of bias and measurement circuitry appropriate to the selected operation conditions.

21. The position sensing photodetector array of claim 18 further defines a pinhole having a perimeter of a predetermined size and shape through said semiconductor substrate.

22. The position sensing photodetector array of claim 21 wherein said position sensing photodetector array provides a means for allowing multiple techniques for determining spatial relationships between said pinhole and illumination from a remote light source incident on said semiconductor substrate surrounding said pinhole.