Method and device for inspecting a surface of an object comprising nonsimilar materials

Patent metadata

Field	Value
Publication number	US-11287246-B2
Application number	US-201916967649-A
Country	US
Kind code	B2
Filing date	Jan 25, 2019
Priority date	Feb 5, 2018
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

A method and related device for measuring the profile of a surface of an object to be measured having zones made from at least two different materials, the object to be measured forming part of a plurality of substantially identical objects, the plurality of objects also including at least one reference object having at least one reference surface, the method including the following steps: determining a correction function, from a first profile signal of a first reference surface and a second profile signal from a second reference surface, the second reference surface being metallized; acquiring a profile signal from the surface of the object to be measured; and applying the correction function to the profile signal from the surface of the object to be measured to obtain a corrected profile signal; the profile signals being obtained from interferometric measurements.

First claim

The invention claimed is:

1. A method for measuring the profile of a surface of an object to be measured, in comprising zones or structures made from at least two different materials, the method comprising a step of:
acquiring a profile signal of the surface of the object to be measured, wherein the object to be measured forms part of a plurality of substantially identical objects, the plurality of objects also comprising at least one reference object having at least one reference surface, the method further comprising the following steps:
acquiring a first reference profile signal of a first reference surface;
acquiring a second reference profile signal of a second reference surface, the second reference surface being metallized;
determining a correction function from the first reference profile signal and the second reference profile signal; and
applying the correction function to the profile signal from the surface of the object to be measured to obtain a corrected profile signal, wherein the first and second reference profile signals are obtained from interferometric measurements.

2. The method according to claim 1 , wherein the steps of acquiring a profile signal of the surface of the object to be measured and applying the correction function are carried out for a plurality of objects to be measured originating from one and the same production series.

3. The method according to claim 2 , wherein the step of determining a correction function is carried out with at least one reference object originating from one and the same production series as the objects to be measured.

4. The method according to claim 1 , wherein the second reference surface corresponds to the first, metallized, reference surface, of one and the same reference object.

5. The method according to claim 1 , wherein the first reference surface and the second reference surface are corresponding surfaces of two different reference objects.

6. The method according to claim 1 , further comprising a metallization step, including deposition of a conforming layer of metal on a reference surface of a reference object.

7. The method according to claim 1 , wherein the step of determining the correction function is carried out at several positions, called positions of interest, of the first and second reference surface, located identically on the first reference surface and the second reference surface, respectively.

8. The method according to claim 7 , wherein:
the step of acquiring a profile signal is carried out at several positions, called measurement positions, of the surface of the object to be measured, located identically to the positions of interest of the reference surfaces, or located in zones of the same materials as the positions of interest; and
the step of applying the correction function is carried out for said measurement positions of the surface of the object, by taking account of the corresponding positions of interest.

9. The method according to claim 1 , wherein the step of determining a correction function comprises a difference between the second reference profile signal and the first reference profile signal.

10. The method according to claim 1 , wherein the step of applying the correction function comprises a summation of a correction profile signal and the profile signal.

11. The method according to claim 1 , further comprising at least one of the following steps:
a step of geometrical alignment of the second profile signal from the second reference surface with respect to the first profile signal from the first reference surface; and
a step of geometrical alignment of the profile signal from the surface of the object to be measured with respect to the first or second profile signal of a reference surface.

12. The method according to claim 1 , wherein the profile of a surface of an object to be measured comprises a substrate such as a wafer, or an element such as a chip produced on a substrate.

13. The method according to claim 12 , further comprising the steps of:
determining a correction function from at least one reference substrate,
acquiring a profile signal from another substrate to be measured.

14. A device for measuring the profile of a surface of an object to be measured, the surface having zones made from at least two different materials, the device comprising:
an interferometric measurement device arranged for acquiring a first profile signal of the surface of the object to be measured, the object to be measured forming part of a plurality of substantially identical objects, the plurality of objects also comprising at least one reference object having at least one reference surface, the interferometric measurement device being further adapted for acquiring a first reference profile signal from a first reference surface and, a second reference profile signal from a second, metallized reference surface; and
a processing module configured in order to determine a correction function from the first reference profile signal and the second reference profile signal, and to apply said correction function to the profile signal from the surface of the object to be measured in order to obtain a corrected profile signal.

15. The device according to claim 14 , wherein the interferometric measurement device comprises a full-field interferometric sensor.

16. The device according to claim 15 , wherein the interferometric sensor comprises one from a phase-shifting interferometer and a vertical scanning interferometer.

Assignees

• Unity Semiconductor
• Commissariat Energie Atomique
• Commissariat A Lenergie Atomique Et Aux Alternatives

Inventors

• Boulanger Jean-François
• Godny Stéphane

Classifications

• G01N21/9501

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title

• G01B11/06

  for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} · CPC title

• G01B11/2441 Primary

  using interferometry · CPC title

• G01N21/45

  using interferometric methods; using Schlieren methods · CPC title