Non-contact method for determining the presence of a contaminant in a semiconductor device

• US 6,255,128 B1
• Filed: 08/06/1998
• Issued: 07/03/2001
• Est. Priority Date: 08/06/1998
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Roy, Pradip K., Chacon, Carlos M.
• Primary Examiner(s): Meier, Stephen D.
• Assistant Examiner(s): VOCKRODT, JEFF B
• Application Number:
  US09/130,240
• Time in Patent Office: 1,062 Days
• Field of Search: 438/14, 438/17, 438/18, 324/452, 324/455, 324/753
• US Class Current: 438/17
• CPC Class Codes: G01N 27/002 by investigating the work function voltage
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

The present invention provides a non-contact method for determining whether a contaminant is present in a semiconductor wafer having a substrate/dielectric interface formed thereon. in one advantageous embodiment, the method comprises field inducing a junction in equilibrium inversion in the semiconductor wafer device. A conventional corona source may be used to induce the junction to equilibrium inversion. This particular embodiment further includes forming a contaminant junction near the substrate/dielectric interface when the contaminant is present in the semiconductor wafer by adding charge and pulsing the junction out of equilibrium. A surface voltage measurement, which may be taken with a Kelvin probe, is obtained by measuring a change in a surface voltage as a function of time. The method further includes determining whether the contaminant is present in the semiconductor wafer from the change in the surface voltage. When the contaminant is present in the device, the change in the surface voltage is negligible. This negligible change is in stark contrast to the change in surface voltage that occurs in a non-contaminated device. The data obtained from these surface voltages can be plotted with conventional devices to yield the change in surface voltage with respect to time.

Claims

1. A non-contact method for determining whether a contaminant is present in a semiconductor wafer having a substrate/dielectric interface formed thereon, comprising:

field inducing a first junction in equilibrium inversion in said semiconductor wafer device;

forming a contaminant junction near said substrate/dielectric interface when said contaminant is present in said semiconductor wafer by adding charge and poising said first junction out of equilibrium;

measuring a change in a surface voltage as a function of time to obtain a surface voltage measurement, said change being negligible when said contaminant is present in said semiconductor wafer; and

determining whether said contaminant is present in said semiconductor wafer from said change in said surface voltage.

2. The method as recited in claim 1 wherein said formation of said contaminant junction inhibits a formation of a deep depletion region within said semiconductor device.

3. The method as recited in claim 1 wherein said semiconductor device comprises a p-type dopant and said contaminant is an n-type dopant.

4. The method as recited in claim 1 wherein said semiconductor device comprises an n-type dopant and said contaminant is a p-type dopant.

5. The method as recited in claim 1 wherein said pulsing is performed with a corona source.

6. The method as recited in claim 1 wherein said measuring is performed with a Kelvin probe.

7. The method as recited in claim 1 wherein said contaminant junction is a p-type junction or an n-type junction.

8. A process for fabricating a semiconductor device, comprising;

forming a substrate/dielectric interface on a semiconductor wafer substrate by growing a dielectric on said semiconductor wafer substrate;

using a non-contact method to determine whether a contaminant is present in said semiconductor device, including;

field inducing a first junction in equilibrium inversion in said semiconductor wafer substrate;

adding charge and pulsing said first junction out of equilibrium, said pulsing forming a contaminant junction near said substrate/dielectric interface when said contaminant is present in said semiconductor device;

measuring a change in a surface voltage as a function of time to obtain a surface voltage measurement, said change being negligible when said contaminant is present in said semiconductor device; and

determining whether said contaminant is present in said semiconductor device from said change in said surface voltage; and

rejecting said semiconductor device if contaminant is present or continuing said fabrication if said contaminant is not present in said semiconductor device.

9. The process as recited in claim 8 wherein said formation of said contaminant junction inhibits a formation of a deep depletion region within said semiconductor device.

10. The process as recited in claim 8 wherein said semiconductor device comprises a p-type dopant and said contaminant is an n-type dopant.

11. The process as recited in claim 8 wherein said semiconductor device comprises an n-type dopant and said contaminant is a p-type dopant.

12. The process as recited in claim 8 wherein said pulsing is performed with a corona source.

13. The process as recited in claim 8 wherein said measuring is performed with a Kelvin probe.

14. The process as recited in claim 8 wherein continuing said fabrication includes:

forming an active region on said semiconductor substrate, said active region comprising a gate formed on said semiconductor substrate, source and drain regions formed within said semiconductor substrate, a dielectric formed over said gate and source and drain regions, contact openings formed within said dielectric and interconnect structures formed on said dielectric to connect said active region to other portions of the semiconductor wafer.