Inspection method using a charged particle beam and inspection device based thereon

• US 20030057971A1
• Filed: 08/01/2002
• Published: 03/27/2003
• Est. Priority Date: 09/27/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nozoe, Mari, Nishiyama, Hidetoshi
• Granted Patent: US 6,853,204 B2
• Time in Patent Office: Days
• US Class Current: 324/751
• CPC Class Codes: G01R 31/305 using electron beams investigating or analysing materials by measuring photoelectric effect G01N23/227

Abstract

A semiconductor defect inspection device and method for detecting defects of partially finished substrates (semiconductor wafers) for semiconductor devices is provided. The substrate surface is irradiated with a charged particle beam and a voltage contrast image is obtained while the charged voltage is controlled at a desired level, and the electric resistances of the irradiated area from the image are calculated to detect a defect and identify the type of defect. Further, the distribution of electric resistances on the whole surface of the substrate can be quickly worked out. The charged particle beam irradiation conditions are varied in order to bring the charged voltage of the area to a desired value. With this device/method, electric resistances of small portions at desired charged voltages and the corresponding electric resistances are measured in a non-contact manner to determine the type of defect. When this inspection method is applied to the PCB manufacturing process, defects can be detected and remedied at an early stage of the process. Consequently, in the semiconductor devices and other PCB related devices, the defect rate decreases and the productivity increase. Since the defect occurrence rate is reduced, the reliability of semiconductor devices is increased, and the efficiency in developing new products is improved.

Claims

1. A semiconductor defect inspection method, comprising:

scanning a specific area on a to-be-inspected object with a charged particle beam;

measuring at least one of secondary electrons and back scattering electrons emitted from the specific area;

calculating a charged voltage of the specific area based upon the measured result, and calculating a corresponding electric resistance value based upon the measured result and an electric current value of the charged particle beam; and

comparing a charged voltage vs. electric resistance characteristic pattern of the to-be-tested object being composed of the changed voltage and the corresponding electric resistance value with a charged voltage vs. electric resistance characteristic pattern of at least one type of defect to determine whether said type of defect exists in the specific area.

2. The semiconductor defect inspection method according to claim 1, further comprising deciding irradiation conditions of the charged particle beam which include the electric current value of the charged particle beam,

wherein the measuring step involves measuring an electron count and an energy level of at least one of secondary electrons and back scattering electrons emitted from the specific area, and

wherein the calculating step involves calculating the charged voltage of the specific area based upon the energy level, and calculating the corresponding electric resistance value based upon the electron count and the electric current value of the charged particle beam.

3. The semiconductor defect inspection method according to claim 1, further comprising:

scanning a plurality of areas on the to-be-tested object with the charged particle beam;

measuring an electron count and an energy level of at least one of secondary electrons and back scattering electrons emitted from each of the plurality of areas;

making a voltage contrast image based upon the measured results; and

comparing a brightness of each area in the voltage contrast image thereby preliminarily determining at least one specific area containing at least one defect.

4. The semiconductor defect inspection method according to claim 1, further comprising:

varying the irradiation conditions to obtain a plurality of desired charged voltages or electric resistance values to constitute the charged voltage vs. electric resistance characteristic pattern of the to-be-tested object.

5. The semiconductor defect inspection method according to claim 4, wherein the irradiation conditions include a beam current of the charged particle beam, a beam energy of the charged particle beam, an irradiation area of the charged particle beam, and a distribution of electric potentials between the object and a electrode around the object.

6. The semiconductor defect inspection method according to claim 1, wherein the step of calculating the correspond electric resistance R is carried out on a condition that the electric current value of the charged particle beam IP is within the range of 0<

log (R·

IP)<

3.

7. The semiconductor defect inspection method according to claim 1, wherein the scanning step involves scanning and charging with the charged particle beam an area wider than the specific area.

8. The semiconductor defect inspection method according to claim 1, wherein said type of defect is junction orientation defect, a leakage defect, or an incomplete contact defect.

9. The semiconductor defect inspection method according to claim 1, further comprising aligning the charged particle beam with the specific area.

10. The semiconductor defect inspection method according to claim 3, further comprising calibrating a signal scale of the voltage contrast image with a model.

11. The semiconductor defect inspection method according to claim 3, wherein the scanning step involves scanning and charging with the charged particle beam an area wider than said each of the plurality of areas for obtaining a corresponding signal for the voltage contrast image.

12. The semiconductor defect inspection method according to claim 3, wherein the step of making the voltage contrast image involves obtaining a voltage contrast image under either a positively or negatively charged condition.

13. A semiconductor defect inspection device, comprising:

deciding means for deciding irradiation conditions of a charged particle beam which include an electric current value of the charged particle beam;

scanning means for scanning a specific area on a to-be-inspected object with the charged particle beam;

measuring means for measuring an electron count and an energy level of at least one of secondary electrons and back scattering electrons emitted from the specific area;

calculation means for calculating a charged voltage of the specific area based upon the energy level, and for calculating a corresponding electric resistance value based upon the electron count and the electric current value of the charged particle beam; and

comparing means for comparing a charged voltage vs. electric resistance characteristic pattern of the to-be-tested object being composed of the changed voltage and the corresponding electric resistance value with the charged voltage vs. electric resistance characteristic pattern of said type of defect to determine whether said type of defect exists in the specific area.

14. The semiconductor defect inspection device according to claim 13, further comprising:

an image processing section for making a voltage contrast image based upon scanned results from the scanning means by scanning a plurality of areas on the to-be-tested object with the charged particle beam and measured results from the measuring means by measuring an electron count and an energy level of at least one of secondary electrons and back scattering electrons emitted from each of the plurality of areas; and

preliminary defect determining means for comparing a brightness of each area in the voltage contrast image thereby preliminarily determining at least one specific area containing at least one defect.

15. The semiconductor defect inspection method according to claim 14, further comprising calibrating means for calibrating a signal scale of the voltage contrast image with the charged voltage vs. electric resistance characteristic pattern of at least one type of defect

16. The semiconductor defect inspection device according to claim 13, further comprising:

a holder for holding a to-be-inspected object; and

a detector for detecting at least one of secondary electrons and back scattering electrons emitted from the specific area,

wherein the scanning means includes an objective lens.

17. The semiconductor defect inspection device according to claim 16, further comprising at least one of a position calibration pattern on the holder, an optical image, and a voltage contrast image, for aligning the holder with the scanning means.

18. The semiconductor defect inspection device according to claim 13, wherein the measuring section includes an electrode for varying the charged voltage by applying a voltage to the surface of the object.

19. The semiconductor defect inspection device according to claim 18, wherein the measuring section further includes a magnetic field applied to the object vertically.

20. The semiconductor defect inspection device according to claim 13, wherein the object is a wafer bearing at least one semiconductor device.