Sample inspection apparatus and sample inspection method

• US 5,960,106 A
• Filed: 03/30/1995
• Issued: 09/28/1999
• Est. Priority Date: 03/31/1994
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tojo, Toru, Watanabe, Toshiyuki, Tsuchiya, Hideo, Kobayashi, Eiichi, Tabata, Mitsuo
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Werner, Brian P.
• Application Number:
  US08/413,704
• Time in Patent Office: 1,643 Days
• Field of Search: 382/149, 382/145, 382/144, 382/141, 382/274, 382/209, 382/217, 382/219, 382/147, 382/148, 382/205, 348/87, 348/126, 356/237.4, 356/237.5, 356/236.6, 356/375, 356/376, 250/559.4, 250/559.41, 250/559.42, 250/559.43, 250/559.44, 250/559.45, 250/559.46, 438/14-18
• US Class Current: 382/144
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/0006 using a design-rule based approach

Abstract

In a method of inspecting a sample on which a pattern relating to fabrication of a semiconductor device is formed, there are provided a light radiation unit, an acquiring unit, a storage unit, a template, a calculation unit, a correction unit, a defect detection unit and an output unit. Pinhole shape data to be detected of the pattern is stored in the template. The calculation unit calculates the degree of coincidence between the pinhole shape data stored in the template and the measured image data stored in the storage unit in units of a predetermined amount of data. The correction unit corrects a portion of the measured image data corresponding to a value of the degree of coincidence exceeding a second predetermined value in units of the predetermined amount of data, when the degree of coincidence obtained by the calculation unit has exceeded a first predetermined value, thereby correcting the portion of the measured image data including the detected pinhole. The defect detection unit detects a defect in the pattern on the basis of the corrected measured image data portion including the pinhole, which is obtained by the correcting unit, and the measured image data.

Claims

1. A sample inspection apparatus comprising:

light radiation means for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

acquiring means for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting means for setting a predetermined lower limit value and a predetermined upper limit value as signal amplitude values for the measured image data acquired by said acquiring means;

normalizing means for normalizing the measured image data acquired by said acquiring means such that a range of amplitude between the lower and upper limit values set by said setting means is 0% to 100% of an ideal amplitude;

clamping means for clamping a portion of the measured image data acquired by said acquiring means, which exceeds the predetermined upper limit value, with the normalized measured image data corresponding to the upper limit value;

gain multiplying means for inverting a portion of the measured image data that is lower than the lower limit value at the lower limit value and multiplying the inverted measured image data portion by a predetermined gain; and

defect detection means for detecting a defect in said pattern by comparing the normalized, clamped, and multiplied measured image data and design data of the pattern.

2. The sample inspection apparatus according to claim 1, wherein the upper and lower limit values in said normalizing means are set by using one of measured image data obtained by inspecting a specified sample before or during an inspection and measured image data written from a computer for controlling the inspection apparatus.

3. The sample inspection apparatus according to claim 1, further comprising a filter for attenuating the amplitude of a high frequency band of the measured image data acquired by said acquiring means.

4. The sample inspection apparatus according to claim 3, wherein said filter is a digital filter.

5. The sample inspection apparatus according to claim 3, wherein said filter includes means for temporarily bypassing the filter.

6. A sample inspection method comprising the steps of:

radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting a predetermined lower limit value and a predetermined upper limit value as signal amplitude values for the measured image data acquired by said sensing step;

normalizing the measured image data acquired by said sensing step such that the range of amplitude between the predetermined lower and upper limit values set by said setting step is 0% to 100% of an ideal amplitude;

clamping a portion of the measured image data acquired by said sensing step, which exceeds the upper limit value, with the normalized measured image data corresponding to the upper limit value;

inverting a portion of the measured image data that is lower than the lower limit value at the lower limit value, and multiplying the inverted measured image data portion by a predetermined gain; and

detecting a defect in said pattern by comparing the normalized, clamped, and multiplied measured image data and design data of the pattern.

7. A sample inspection apparatus comprising:

a light radiation unit for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

an acquiring unit for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

a normalizing circuit including

a setting section for setting a predetermined lower limit value and a predetermined upper limit value as signal amplitude values for the measured image data acquired by said acquiring unit,

a normalizing section for normalizing the measured image data acquired by said acquiring unit such that a range of amplitudes between the lower and upper limit values set by said setting section is 0% to 100% of an ideal amplitude,

a clamping section for clamping a portion of the measured image data acquired by said acquiring unit, which exceeds the upper limit value, with the normalized measured image data corresponding to the upper limit value,

a gain multiplying section for inverting a portion of the measured image data that is lower than the lower limit value at the lower limit value and multiplying the inverted measured image data portion by a predetermined gain, and

a defect detection section for detecting a defect in said pattern by comparing the normalized clamped, and multiplied image data and design data of the pattern.

8. A sample inspection apparatus comprising:

light radiation means for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

acquiring means for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting means for setting a predetermined lower limit value as a signal amplitude value for the measured image data acquired by said acquiring means, and for setting a non-sensitive band having a signal amplitude of δ

1 to a positive side and a signal amplitude of δ

2 to a negative side with respect to the lower limit value;

gain multiplying means for inverting a portion of the measured image data lower than δ

2 when the signal amplitude of the measured image data acquired by said acquiring means is lower than δ

2, and multiplying the inverted measured image data by a predetermined gain; and

clamping means for clamping the signal amplitude of a portion of the measured image data acquired by said acquiring means, which is present in said non-sensitive band, with the measured image data corresponding to the lower limit value; and

defect detection means for detecting a defect in said pattern by comparing the multiplied and clamped image data and design data of the pattern.

9. The sample inspection apparatus according to claim 8, wherein the lower limit value and said signal amplitudes δ

1 and δ

2 in said setting means are set by using one of measured image data obtained by inspecting a specified sample before or during an inspection and measured image data received from a computer for controlling the inspection apparatus.

10. The sample inspection apparatus according to claim 8, further comprising a filter for attenuating the signal amplitude of a high frequency band of the measured image data acquired by said acquiring means.

11. The sample inspection apparatus according to claim 10, wherein said filter includes means for temporarily bypassing the filter.

12. A sample inspection apparatus comprising:

a light radiation unit for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

an acquiring unit for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern; and

a normalizing circuit including

a setting section for setting a predetermined lower limit value as a signal amplitude value for the measured image data acquired by said acquiring unit, and for setting a non-sensitive band having a signal amplitude of δ

1 to a positive side and a signal amplitude of δ

2 to a negative side with respect to the lower limit value,

a gain multiplying section for inverting a portion of the measured image data lower than δ

2 when the signal amplitude of the measured image data acquired by said acquiring unit is lower than δ

2, and multiplying the inverted measured image data by a predetermined gain,

a clamping section for clamping the signal amplitude of a portion of the measured image data acquired by said acquiring unit, which is present in said non-sensitive band, with measured image data corresponding to the lower limit value, and

a defect detection section for detecting a defect in said pattern by comparing the multiplied and clamped image data and design data of the pattern.

13. A sample inspection method comprising the steps of:

radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting a predetermined lower limit value as a signal amplitude value for the measured image data acquired by said sensing step and setting a non-sensitive band having a signal amplitude of δ

1 to a positive side and a signal amplitude of δ

2 to a negative side with respect to the lower limit value;

inverting a portion of the measured image data lower than δ

2 when the signal amplitude of the measured image data acquired by said sensing step is lower than δ

2, and multiplying the inverted measured image data by a predetermined gain;

clamping the signal amplitude of a portion of the measured image data acquired by said sensing step, which is present in said non-sensitive band, with normalized measured image data corresponding to the lower limit value; and

detecting a defect in said pattern by comparing the multiplied and clamped image data and design data of the pattern.

14. A sample inspection apparatus comprising:

light radiation means for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

acquiring means for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

lower limit value setting means for setting a predetermined lower limit value for the measured image data acquired by said acquiring means;

threshold setting means for setting a predetermined threshold on a negative side of the predetermined lower limit value set by said lower limit value setting means;

gain multiplying means for inverting the measured image at the lower limit value when a signal amplitude of the measured image data is between said lower limit value and said threshold, and multiplying the inverted measured image data by a predetermined gain;

adjusting means for bias-clamping, when the signal amplitude of the measured image data is lower than said threshold, the measured image data with normalized measured image data corresponding to the threshold, or attenuating the measured image data lower than said threshold such that a signal value of the measured image data decreases gradually to 0% of the normalized measured image data, to obtain corrected measured image data; and

defect detection means for detecting a defect in said pattern by comparing the multiplied and corrected measured image data and design data of the pattern.

15. The sample inspection apparatus according to claim 14, wherein the lower limit value and said threshold are set by using one of measured image data obtained by inspecting a specified sample before or during an inspection and measured image data received from a computer for controlling the inspection apparatus.

16. The sample inspection apparatus according to claim 14, further comprising a filter for attenuating the signal amplitude of a high frequency band of the measured image data acquired by said acquiring means.

17. The sample inspection apparatus according to claim 16, wherein said filter includes means for temporarily bypassing the filter.

18. A sample inspection apparatus comprising:

a light radiation unit for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

an acquiring unit for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern; and

a normalizing circuit including

a lower limit value setting section for setting a predetermined lower limit value for the measured image data acquired by said acquiring unit,

a threshold setting section for setting a predetermined threshold on a negative side of the lower limit value set by said lower limit value setting section,

a gain multiplying section for inverting the measured image at the lower limit value when a signal amplitude of the measured image data is between said lower limit value and said threshold, and multiplying the inverted measured image data by a predetermined gain,

an adjusting section for bias-clamping, when the signal amplitude of the measured image data is lower than said threshold, the measured image data with normalized measured image data corresponding to the threshold, or attenuating the measured image data lower than said threshold such that a signal value of the measured image data decreases gradually to 0% of the normalized measured image data to obtain corrected measured image data, and

a defect detection section for detecting a defect in said pattern by comparing the multiplied and corrected measured image data and design data of the pattern.

19. A sample inspection method comprising the steps of:

radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting a predetermined lower limit value for the measured image data acquired by said sensing step;

setting a predetermined threshold on a negative side of the lower limit value set by said setting step;

inverting the measured image at the lower limit value when a signal amplitude of the measured image data is between said lower limit value and said threshold, and multiplying the inverted measured image data by a predetermined gain;

bias-clamping, when the signal amplitude of the measured image data is lower than said threshold, the measured image data with normalized measured image data corresponding to the threshold, or attenuating the measured image data lower than said threshold such that a signal value of the measured image data decreases gradually to 0% of the normalized measured image data to obtain corrected measured image data; and

detecting a defect in said pattern by comparing the multiplied and corrected measured image data and design data of the pattern.

20. A sample inspection apparatus comprising:

light radiation means for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

acquiring means for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

lower limit value setting means for setting a predetermined lower limit value for the measured image data acquired by said acquiring means;

threshold setting means for setting a predetermined first threshold and a predetermined second threshold on a negative side of said lower limit value;

gain multiplying means for inverting a portion of the measured image data lower than the lower limit value at the lower limit value when a signal amplitude of the measured image data is between said predetermined lower limit value and said first threshold, and multiplying the inverted measured image data by a predetermined gain;

shifting means for shifting the signal amplitude of the measured image data to zero toward the second threshold when the signal amplitude of the measured image data is between the first threshold and the second threshold;

bias-clamping means for bias-clamping the measured image data at a chrome level when the signal amplitude of the measured image data is below the second threshold to obtain corrected measured image data; and

defect detection means for detecting a defect in said pattern by comparing the multiplied, shifted, and corrected measured image data and design data of the pattern.

21. The sample inspection apparatus according to claim 20, wherein the lower limit value and said first and second thresholds in said threshold setting means are set by using one of measured image data obtained by inspecting a specified sample before or during an inspection and measured image data received from a computer for controlling the inspection apparatus.

22. The sample inspection apparatus according to claim 20, further comprising a filter for attenuating the signal amplitude of a high frequency band of the measured image data acquired by said acquiring means.

23. The sample inspection apparatus according to claim 22, wherein said filter includes means for temporarily bypassing the filter.

24. A sample inspection apparatus comprising:

a light radiation unit for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

an acquiring unit for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern; and

a normalizing circuit including

lower limit value setting means for setting a predetermined lower limit value for the measured image data acquired by said acquiring means,

a threshold setting section for setting a predetermined first threshold and a predetermined second threshold on a negative side of said lower limit value,

a gain multiplying section for inverting a portion of the measured image data lower than the lower limit value at the lower limit value when a signal amplitude of the measured image data is between said lower limit value and said first threshold, and multiplying the inverted measured image data by a predetermined gain,

a shifting section for shifting the signal amplitude of the measured image data to zero toward the second threshold when the signal amplitude of the measured image data is between the first threshold and the second threshold,

a bias-clamping section for bias-clamping the measured image data at a chrome level when the signal amplitude of the measured image data is below the second threshold to obtain corrected measured image data, and

a defect detection section for detecting a defect in said pattern by comparing the multiplied, shifted, and corrected measured image data and design data of the pattern.

25. A sample inspection method comprising the steps of

radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

setting a predetermined lower limit value for the measured image data acquired by said sensing step;

setting a predetermined first threshold and a predetermined second threshold on a negative side of said lower limit value;

inverting a portion of the measured image data lower than the lower limit value at the lower limit value when a signal amplitude of the measured image data is between said predetermined lower limit value and said first threshold, and multiplying the inverted measured image data by a predetermined gain;

shifting the signal amplitude of the measured image data to zero toward the second threshold when the signal amplitude of the measured image data is between the first threshold and the second threshold;

bias-clamping the measured image data at a chrome level when the signal amplitude of the measured image data is below the second threshold to obtain corrected measured image data; and

detecting a defect in said pattern by comparing the multiplied shifted, and corrected measured image data and design data of the pattern.

26. A sample inspection apparatus comprising:

light radiation section for radiating light on a sample on which a pattern relating to fabrication of a semiconductor device is formed;

an acquiring section for sensing the light which has passed through the sample, thereby acquiring measured image data constituting a light transmission image of said pattern;

a storage section for storing the measured image data acquired by said acquiring section;

a pinhole detection section for detecting a pinhole in said pattern on the basis of the measured image data stored in said storage section, said pinhole detection section comprising

an extraction circuit for extracting a value of a center pixel of the measured image data stored in said storage section and values of pixels surrounding the center pixel in a multiple manner,

a determination circuit for determining the presence of the pinhole in said pattern by a difference between the value of the center pixel extracted by said extraction circuit and the values of the surrounding pixels, and

a filter for filtering said measured image data which includes the determined pinhole so as to attenuate a high frequency band amplitude of said measured image data including the determined pinhole;

a defect detection section for detecting a defect in said pattern on the basis of the filtered measured image data, including the determined pinhole, which is obtained by said filter, and said measured image data; and

an output section for outputting a detection result of said defect detection section.

27. A sample inspection apparatus according to claim 26, wherein said filter is one of a FIR filter and an IIR filter.

28. A sample inspection apparatus according to claim 26, further comprising:

a setting section for setting a predetermined lower limit value and a predetermined upper limit value as signal amplitude values for the measured image data filtered by said filter;

normalizing means for normalizing the measured image data filtered by said filter such that a range of amplitude between the lower and upper limit values set by said setting section is 0% to 100% of an ideal amplitude;

a clamping section for clamping a portion of the measured image data filtered by said filter which exceeds the upper limit value with the normalized measured image data corresponding to the upper limit value; and

a gain multiplying section for inverting a portion of the measured image data that is lower than the lower limit value at the lower limit value and multiplying the inverted measure image data portion by a predetermined gain, thereby providing the inverted measured image data as the filtered measured image data portion in the defect detection section.