Circuit testing method and apparatus
AssigneeTextronix, Inc.
InventorPhilip S. Crosby
Life of this patent
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Abstract
A testing method and apparatus employs electron beam writing and reading of conductive paths in a circuit device rather than physical probing of conductive elements. Portions of the circuit device, e.g., conductive paths, are bistably stored at a given potential and then the device is read by a reading beam to determine if proper connections exist. Read out is at comparatively high levels represented by the difference between bistable voltage values. Once a portion of the device has been tested, it may remain in stored condition such that additional cross checking or repetition of testing is rendered unnecessary.
Claims17
The method of testing a circuit device characterized by conductive circuit paths including a first circuit path, said method comprising:
- positioning said circuit device in a substantially evacuated chamber,
- directing a flood beam of electrons toward said circuit device for establishing a surface of said circuit device at a first stable potential, and
- directing a writing beam of electrons toward a selected portion of a first circuit path of said circuit device for changing the potential of said portion such that said flood beam of electrons maintains said portion at a second stable potential,
- wherein said second stable potential is on the opposite side of the first crossover in the secondary emission characteristic for said portion from said first stable potential.
An apparatus for testing a circuit device characterized by conductive paths, said apparatus comprising:
- a chamber for receiving said circuit device,
- a target electrode positioned proximate said circuit device as received within said chamber,
- a first electron source for directing a higher energy beam of electrons toward said circuit device,
- means for applying a preparation potential to said target electrode in the presence of flood electrons from said first electron source for bringing a surface of said circuit device to a first stable potential, and
- means for directing said beam of electrons from said second electron source toward a selected portion of said circuit device comprising part of a given said circuit path for altering the potential of said portion so that said flood beam stores the potential of said portion at a second stable potential on the opposite side of the first crossover in the secondary emission characteristic for said portion from said first stable potential.
An apparatus for testing a circuit device characterized by conductive paths, said apparatus comprising:
- a chamber for receiving said circuit device,
- a target electrode positioned proximate said circuit device as received within said chamber,
- a first electron source for directing flood electrons toward said circuit device and means for applying voltage to said target electrode relative to said first electron source for enabling bistable potential storage at locations on said circuit device at first and second stable potentials on either side of the first crossover in the secondary emission characteristic for materials at said locations,
- a second electron source for directing a higher energy beam of electrons toward said circuit device, and
- means for directing said beam of electrons from said second electron source toward a selected portion of said circuit device comprising part of a given said circuit path for altering the potential of said portion from said first stable potential so that said flood beam stores the potential of said portion at said second stable potential.
Dependencies are inferred from the claim text.