Optical coupling for testing integrated circuits

• US 6,985,219 B2
• Filed: 12/21/2000
• Issued: 01/10/2006
• Est. Priority Date: 12/21/2000
• Status: Expired due to Term

• Current Assignee: FEI EFA, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Wilsher, Kenneth R., Kasapi, Steven A
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US09/746,618
• Publication Number:
  US 20020113958A1
• Time in Patent Office: 1,846 Days
• Field of Search: 356/237.1, 324/752, 324/753
• US Class Current: 356/237.1
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence
• CPC Class Codes: G01R 31/31905 Interface with the device under test [DUT], e.g. arrangements between the test head and the DUT, mechanical aspects, fixture

Abstract

A method and system of testing integrated circuits (IC) via optical coupling. The optical system includes an optical fiber, fixture and focussing element. In addition, channels are provided in the fixture mounted on the integrated circuit to accommodate the optical system. The fixture acts as a heat sink. As such, one or more photosensitive elements/targets on the integrated circuit are probed using light that is brought to a focus on each target site. The light causes latching of data into the integrated circuit (which is operating under influence of a test program) and formation of a test pattern output from the integrated circuit that is used to confirm proper functioning of the IC.

Claims

1. A method of testing a device under test having an operating integrated circuit on a fixture comprising the acts of:

inserting an optical fiber into a hole defined in said fixture;

applying light from a light source to a proximal end of said fiber;

focusing said light as it exits a distal end of said fiber onto a photosensitive element of said integrated circuit thereby to cause latching of data into said integrated circuit;

capturing light at a proximal end of said fiber reflected by said element; and

analyzing said reflected light for proper focusing of said light onto said element.

2. A method of testing a device under test having an operating integrated circuit on a fixture comprising the acts of:

inserting an optical fiber into a hole defined in said fixture;

applying light from a light source to a proximal end of said fiber;

focusing said light as it exits a distal end of said fiber onto a photosensitive element of said integrated circuit thereby to cause latching of data into said integrated circuit;

capturing light at a proximal end of said fiber reflected by said element; and

analyzing said reflected light to determine whether said light is correctly coupled into said fiber.