System and method for determining near--surface lifetimes and the tunneling field of a dielectric in a semiconductor

• US 6,011,404 A
• Filed: 07/03/1997
• Issued: 01/04/2000
• Est. Priority Date: 07/03/1997
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ma, Yi, Roy, Pradip K.
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): SUNDARAM, T R
• Application Number:
  US08/887,861
• Time in Patent Office: 915 Days
• Field of Search: 324/767, 324/765, 324/158.1, 324/769
• US Class Current: 324/754.05
• CPC Class Codes: G01R 31/265 Contactless testing of circuits, also in wafer-form G01R31/302
• CPC Class Codes: G01R 31/2831 Testing of materials or semi-finished products, e.g. semiconductor wafers or substrates G01R31/318511 takes precedence; testing during manufacture H01L22/00
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means

Abstract

The present invention is directed to a system for, and method of, determining a non-contact, near-surface generation and recombination lifetimes and near surface doping of a semiconductor material. The system includes: (1) a radiation pulse source that biases a dielectric on top of the semiconductor material, (2) a voltage sensor to sense the surface voltage, and (3) a photon source to create carriers. For lifetime measurements both the excitation and measurement signals are time dependent and may be probed near the surface of the semiconductor to obtain various electrical properties. For high-field tunneling and leakage characteristics of a thin dielectric (<15 nm) on top of the semiconductor, a high bias charge density is used to induce tunneling, from which tunneling fields and charge-fluence to tunneling of the dielectric are determined.

Claims

1. A non-contact method for determining electrical properties of a semiconductor material, comprising the steps of:

field inducing a junction in equilibrium inversion in said semiconductor material;

pulsing said junction out of equilibrium to create a deep depletion region proximate said junction;

measuring a surface voltage proximate said junction while performing said step of pulsing; and

determining generation lifetime of said semiconductor material, said generation lifetime being a function of a rate of change of said surface voltage.

2. The method as recited in claim 1 further comprising the step of bombarding said semiconductor material with photons to collapse said deep depletion region after performing said step of measuring.

3. The method as recited in claim 2 further comprising the steps of measuring a surface photovoltage proximate said junction while performing said step of bombarding and determining a recombination lifetime, said recombination lifetime of said semiconductor material being a function of a rate of change of said surface photovoltage.

4. The method as recited in claim 2 wherein said step of bombarding is performed with a photon source.

5. The method as recited in claim 3 further comprising the step of determining a near-surface doping of said semiconductor material from said recombination lifetime.

6. The method as recited in claim 1 wherein said step of measuring comprises the step of allowing said surface voltage to attain a desired value.

7. The method as recited in claim 1 wherein said semiconductor material is silicon-based.

8. The method as recited in claim 1 wherein said semiconductor material is silicon oxide having a thickness less than 10.0 nm.

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

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

11. The method as recited in claim 1 wherein said method further includes the step of:

determining electrical characteristics using a combination of charge deposition, non-contact voltage measurement and surface photovoltage response to build a quasi-static sweep from inversion to accumulation to measure the said dielectric material selected form the group consisting of;

charge-trapping,

hot leakage,

mobile ion density,

interface trap density,

flatband voltage, and

dielectric thickness.

12. A non-contact method of determining near-surface generation and recombination lifetimes of a semiconductor material, comprising the steps of:

field inducing a junction in equilibrium inversion in said semiconductor material;

pulsing said junction out of equilibrium to create a deep depletion region proximate said junction;

measuring a surface voltage proximate said junction while performing said step of pulsing and determining a generation lifetime of said semiconductor material, said generation lifetime being a function of a rate of change of said surface voltage;

bombarding said semiconductor material with photons to collapse said deep depletion region after performing said step of measuring;

measuring a surface photovoltage proximate said junction while performing said step of bombarding; and

determining a recombination lifetime, said recombination lifetime of said semiconductor material being a function of a rate of change of said surface photovoltage.

13. The method as recited in claim 12 wherein said step of bombarding is performed with a photon source.

14. The method as recited in claim 12 further comprising the step of determining a near-surface doping of said semiconductor material from said recombination lifetime.

15. The method as recited in claim 12 wherein said step of measuring comprises the step of allowing said surface voltage to attain a desired value.

16. The method as recited in claim 12 wherein said semiconductor material is silicon-based.

17. The method as recited in claim 12 wherein said semiconductor material is silicon oxide having a thickness less than 10.0 nm.

18. The method as recited in claim 12 wherein said step of pulsing is performed with a corona source.

19. The method as recited in claim 12 wherein said step of measuring is performed with a Kelvin probe.

20. The method as recited in claim 12 wherein said method further includes the step of:

determining electrical characteristics using a combination of charge deposition, non-contact voltage measurement and surface photovoltage response to build a quasi-static sweep from inversion to accumulation to measure the said dielectric material selected form the group consisting of;

charge-trapping,

hot leakage,

mobile ion density,

interface trap density,

flatband voltage, and

dielectric thickness.

21. A non-contact method for determining high-field tunneling characteristics of a semiconductor material having a dielectric deposited thereon, comprising the steps of:

electrically biasing said semiconductor material to a surface voltage where tunneling begins to dissipate a deposited charge on said semiconductor material; and

determining a tunneling voltage of said dielectric from said surface voltage, said tunneling voltage indicating a resistance of said oxide to tunneling.

22. The method as recited in claim 21 wherein the step of determining said tunneling voltage includes allowing said surface voltage to attain a desired value.

23. The method as recited in claim 21 wherein said semiconductor material is silicon-based.

24. The method as recited in claim 21 wherein said semiconductor material is silicon oxide having a thickness less than 15.0 nm.

25. The method as recited in claim 21 wherein said step of electrically biasing includes using a corona source.

26. The method as recited in claim 21 wherein said step of measuring includes using a Kelvin probe to measuring said surface voltage.

27. The method as recited in claim 21 wherein said surface voltage decreases as a function of a charge density of said electrical bias.

28. The method as recited in claim 21 wherein said surface voltage increases overtime during an increase in said electrical bias.

29. The method as recited in claim 21 further comprising the step of determining a charge fluence from said tunneling voltage.

30. The method as recited in claim 21 further comprising the step of determining a field oxide leakage from said tunneling field.