TRENCH PHOTODETECTOR

• US 20070222015A1
• Filed: 05/18/2007
• Published: 09/27/2007
• Est. Priority Date: 11/01/2004
• Status: Abandoned Application

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Divakaruni, Ramachandra, Cheng, Kangguo, Radens, Carl
• Application Number:
  US11/750,423
• Publication Number:
  US 20070222015A1
• Time in Patent Office: Days
• US Class Current: 257/458
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Trench type PIN photodetectors are formed by etching two sets of trenches simultaneously in a semiconductor substrate, the wide trenches having a width more than twice as great as the narrow trenches by a process margin; conformally filling both types of trenches with a sacrificial material doped with a first dopant and having a first thickness slightly greater than one half the width of the narrow trenches, so that the wide trenches have a remaining central aperture; stripping the sacrificial material from the wide trenches in an etch that removes a first thickness, thereby emptying the wide trenches; a) filling the wide trenches with a second sacrificial material of opposite polarity; or b) doping the wide trenches from the ambient such as by gas phase doping, plasma doping, ion implantation, liquid phase doping, infusion doping and plasma immersion ion implantation; diffusing the dopants into the substrate, forming p and n regions of the PIN diode; removing the first and the second sacrificial materials, and filling both the wide and the narrow sets of trenches with the same conductive material in contact with the diffused p and n regions.

Claims

1. A PIN photodetector having a set of p regions and a set of n regions separated by a set of photon detector regions in a solid state wafer comprising:

two sets of trenches, separated by a set of photon detection regions, in said solid state wafer, one wide set of trenches being wider than the other narrow set, such that;

the wide set has a remaining central aperture when the narrow set is filled with a conformally deposited material;

the p and n regions of the PIN photodetector are formed in the substrate adjacent to the two sets of deep trenches; and

both the wide and the narrow sets of trenches are filled with the same conductive electrodes connected to said p and n regions.

2. A photodetector according to claim 1, in which the width of said wide trenches is more than twice as great as the width of said narrow trenches.

3. A photodetector according to claim 1, in which the conductive material electrodes are formed from at least one metal or metal silicide.

4. A photodetector according to claim 3, in which the conductive electrodes are formed from at least one metal or metal silicide selected from the group consisting of:

W, Ti, Ta, TiN, WN, TaN, WSi, TiSi, CoSi, NiSi.

5. A photodetector according to claim 1, in which the solid state wafer is a silicon-on-insulator wafer.

6. A photodetector according to claim 5, in which the width of said wide trenches is more than twice as great as the width of said narrow trenches.

7. A photodetector according to claim 6, in which the conductive electrodes are formed from at least one metal or metal silicide selected from the group consisting of:

W, Ti, Ta, TiN, WN, TaN, WSi, TiSi, CoSi, NiSi.