Non-contact electrical conduction measurement for insulating films

• US 6,202,029 B1
• Filed: 06/20/2000
• Issued: 03/13/2001
• Est. Priority Date: 04/23/1997
• Status: Expired due to Term

• Current Assignee: Gregory S. Horner, Roger L. Verkuil, Tom G. Miller
• Original Assignee: Gregory S. Horner, Roger L. Verkuil, Tom G. Miller
• Inventors: Horner, Gregory S., Miller, Tom G., Verkuil, Roger L.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/597,503
• Time in Patent Office: 266 Days
• Field of Search: 702/64, 702/65, 324/750, 324/765, 324/766, 324/767, 250/492.2, 438/14, 438/17
• US Class Current: 702/64
• CPC Class Codes: G01R 31/2648 Characterising semiconductor materials testing of materials or semi-finished products G01R31/2831; testing during manufacture H01L22/00

Abstract

A corona source is used to apply charge to an insulating layer. The resulting voltage over time is used to determine the current through the layer. The resulting data determines a current-voltage characteristic for the layer and may be used to determine the tunneling field for the layer.

Claims

1. A method for measuring a current-voltage characteristic for an insulating layer on a substrate, said method comprising:

depositing increments of corona charge on said layer;

measuring a voltage and a derivative of said voltage resulting from a reduction in said charge with respect to time; and

determining from said voltage and voltage derivative said current-voltage characteristic.

2. A method according to claim 1, further comprising:

making a calibrating work function voltage measurement of a known material; and

correcting said current-voltage characteristic according to said calibrating work function voltage.

3. A method according to claim 1, further comprising:

making a surface photovoltage measurement for said layer; and

correcting said current-voltage characteristic according to said surface photovoltage measurement.

4. A method for measuring a current-voltage characteristic for an insulating layer on a substrate, said method comprising:

(a) depositing an increment of corona charge on said layer;

(b) measuring a first voltage across said layer;

(c) pausing an increment of time and then measuring a second voltage across said layer;

(d) determining a difference between said first and second voltages;

(e) determining a value for current across said layer from said difference and said increment of time; and

(f) repeating steps a-e to determine said current-voltage characteristic.

5. A method according to claim 4, further comprising:

making a calibrating work function voltage measurement of a known material; and

correcting said current-voltage characteristic according to said calibrating work function voltage.

6. A method according to claim 4, further comprising:

making a surface photovoltage measurement for said layer; and

correcting said current-voltage characteristic according to said surface photovoltage measurement.

7. A method according to claim 4, further comprising measuring an initial voltage across said layer and forcing the potential of the oxide layer to zero by depositing an initial corona charge on said layer.

8. A method for measuring tunneling field for an oxide layer on a semiconductor wafer, said method comprising:

depositing a predetermined value of excess charge on said layer;

measuring a voltage across said layer; and

determining the tunneling field in accordance with said voltage.

9. A method according to claim 8, further comprising:

making a calibrating work function voltage measurement of a known material; and

correcting said current-voltage characteristic according to said calibrating work function voltage.

10. A method according to claim 8, further comprising:

making a surface photovoltage measurement for said layer; and

correcting said current-voltage characteristic according to said surface photovoltage measurement.