Calculated electrical performance metrics for process monitoring and yield management

Patent metadata

Field	Value
Publication number	US-10079183-B2
Application number	US-201414312568-A
Country	US
Kind code	B2
Filing date	Jun 23, 2014
Priority date	Jun 26, 2013
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

Methods and systems of process control and yield management for semiconductor device manufacturing based on predictions of final device performance are presented herein. Estimated device performance metric values are calculated based on one or more device performance models that link parameter values capable of measurement during process to final device performance metrics. In some examples, an estimated value of a device performance metric is based on at least one structural characteristic and at least one band structure characteristic of an unfinished, multi-layer wafer. In some examples, a prediction of whether a device under process will fail a final device performance test is based on the difference between an estimated value of a final device performance metric and a specified value. In some examples, an adjustment in one or more subsequent process steps is determined based at least in part on the difference.

First claim

What is claimed is:

1. A method comprising:
illuminating a measurement site of an unfinished, multi-layer semiconductor wafer with illumination light;
polarizing the illumination light before incidence on the semiconductor wafer;
analyzing light collected from the measurement site of the semiconductor wafer in response to the polarized illumination light provided to the semiconductor wafer;
detecting the analyzed light with a spectrometer;
generating a measured spectral response of the measurement site of the unfinished, multi-layer semiconductor wafer from the analyzed light detected by the spectrometer, the measured spectral response comprising measurement data;
determining a structural characteristic of the unfinished, multi-layer semiconductor wafer based at least in part on the measurement data;
determining a dispersion metric associated with a layer of the unfinished, multi-layer semiconductor wafer based at least in part on the measurement data;
determining a band structure characteristic indicative of an electrical performance of a portion of the multi-layer semiconductor wafer based at least in part on the dispersion metric;
determining an estimate of one or more device performance metrics of the multi-layer semiconductor wafer, as if the unfinished, multi-layer semiconductor wafer were finished, based at least in part on the band structure characteristic and the structural characteristic;
determining an adjustment in one or more subsequent process steps based on a difference between the estimated values of the one or more device performance metrics and one or more corresponding specified final device performance values, wherein the adjustment includes a change in a targeted nominal process value of a subsequent process step; and
communicating an indication of the adjustment to a fabrication tool to perform the subsequent process step in accordance with the adjustment.

2. The method of claim 1 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer at a first process step and measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer at a second process step.

3. The method of claim 1 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer by an optical measurement system and measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer by a measurement system different from the optical measurement system.

4. The method of claim 1 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer performed by one or more of any of an optically based measurement tool, an e-beam based measurement tool, and an x-ray based measurement tool.

5. The method of claim 1 , wherein the measurement data includes measurement data associated with measurements over a first spectral range, and wherein the band structure characteristic indicative of the electrical performance of the unfinished, multi-layer semiconductor wafer is based at least in part on the dispersion metric of the unfinished, multi-layer semiconductor wafer across a second spectral range within the first spectral range.

6. The method of claim 1 , further comprising:
determining whether a device under process is expected to fail a final device performance test based on comparing the estimate of a device performance metric value and a specified final device performance value.

7. The method of claim 1 , wherein the band structure characteristic is an interpolated band gap of an electrically insulative layer disposed above a semiconductor substrate and the determining of the interpolated band gap involves curve fining and interpolation of the optical dispersion metric.

8. The method of claim 1 , wherein the band structure characteristic is a band edge of an electrically insulative layer disposed above a semiconductor substrate and the determining of the band edge involves determining that the optical dispersion metric exceeds a threshold value.

9. The method of claim 1 , wherein the band structure characteristic is a band broadening associated with an electrically insulative layer disposed above a semiconductor substrate and the determining of the band broadening involves determining an interpolated band gap and a band edge of the first layer and determining a difference between the band edge and the interpolated band gap.

10. The method of claim 1 , wherein the band structure characteristic is a defect and the determining of the defect involves determining whether the optical dispersion metric exceeds a threshold value over a spectral range below a band gap of an electrically insulative layer disposed above a semiconductor substrate.

11. A measurement system comprising:
an illuminator that provides illumination light to a measurement site of an unfinished, multi-layer semiconductor wafer;
a spectrometer that detects light from the measurement site in response to the illumination light and generates a measured spectral response of the measurement site, the measured spectral response comprising measurement data; and
a non-transitory, computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to:
determine a structural characteristic of the unfinished, multi-layer semiconductor wafer based at least in part on the measurement data;
determine a dispersion metric associated with a layer of the unfinished, multi-layer semiconductor wafer based at least in part on the measurement data;
determine a band structure characteristic indicative of an electrical performance of a portion of the multi-layer semiconductor wafer based at least in part on the dispersion metric;
determine an estimate of one or more device performance metrics of the multi-layer semiconductor wafer, as if the unfinished, multi-layer semiconductor wafer were finished, based at least in part on the band structure characteristic and the structural characteristic;
determine an adjustment in one or more subsequent process steps based on a difference between the estimated values of the one or more device performance metrics and one or more corresponding specified final device performance values, wherein the adjustment includes a change in a targeted nominal process value of a subsequent process step; and
communicate an indication of the adjustment to a fabrication tool to perform the subsequent process step in accordance with the adjustment.

12. The measurement system of claim 11 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer at a first process step and measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer at a second process step.

13. The measurement system of claim 11 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer by an optical measurement system and measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer by a measurement system different from the optical measurement system.

14. The measurement system of claim 11 , wherein the measurement data includes measurement data associated with a measurement of the unfinished, multi-layer semiconductor wafer performed by one or more of any of an optically based measurement tool, an e-beam based measurement tool, and an x-ray based measure

Assignees

• Kla Tencor Corp
• Kla Tenor Corp

Inventors

• Gao Xiang
• Flanner Iii Philip D
• Poslavsky Leonid
• Di ming
• Zhao Qiang
• Penner Scott

Classifications

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H10P74/203 Primary

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• G01N21/211

  Ellipsometry (optical thickness measurement G01B11/06) · CPC title

• G01N2021/213

  Spectrometric ellipsometry · CPC title

• H01L22/12 Primary

  Electricity · mapped topic