Low drift system for a metrology instrument

Patent metadata

Field	Value
Publication number	US-10900997-B2
Application number	US-201916696724-A
Country	US
Kind code	B2
Filing date	Nov 26, 2019
Priority date	Nov 26, 2018
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

The present inventors have recognized that more accurate measurements can be taken with less drift due to thermal expansion by precisely controlling insulated heating and cooling modules abutting one another in substantial alignment to rapidly heat a sample to be scanned by a Scanning Probe Microscope (SPM) with minimal temperature variation. The heating and cooling modules can be “flat-packed,” with parallel surfaces of each module in contact with one another, to more efficiently heat a sample that is positioned in axial alignment with the heating and cooling modules. This can allow heating the sample to at least 250 degrees Celsius in less than 5 seconds, continuously maintaining a temperature of the sample to within ±0.001 degree Celsius, and maintaining a drift of less than 0.1 nanometers per minute in the z direction.

First claim

What is claimed is:

1. A low drift heater assembly of a metrology instrument for measuring a sample, the low drift heater assembly comprising:
a structure for supporting the sample, the structure being configured to provide a low thermal mass that is operable to maintain a drift of the sample to less than 0.1 nanometers per minute.

2. The heater assembly of claim 1 , wherein the structure comprises:
a heating module providing a heat source; and
a cooling module for cooling the heat source,
wherein the heating and cooling modules abut one another in axial alignment, and
wherein the heating and cooling modules are simultaneously active to control heat transfer through axial alignment to the sample.

3. The heater assembly of claim 2 , wherein the heating and cooling modules are controlled in at least one closed-loop control system.

4. The heater assembly of claim 2 , wherein the heat transfer is operable to heat the sample to at least 250 degrees Celsius in less than 5 seconds.

5. The heater assembly of claim 2 , wherein the heat transfer is operable to maintain a temperature of the sample to within ±0.001 degree Celsius.

6. The heater assembly of claim 2 , wherein a flat surface of the heating module directly abuts a flat surface of the cooling module with a thermal interface material disposed in between.

7. The heater assembly of claim 2 , wherein the heating module comprises an electrically controlled heater component enclosed by an insulating structure.

8. The heater assembly of claim 7 , wherein the insulating structure comprises a ceramic cylinder circumferentially surrounding the heater component and a ceramic disk separating the heater component from the cooling module.

9. The heater assembly of claim 8 , wherein the ceramic cylinder and the ceramic disk include dissimilar ceramic materials.

10. The heater assembly of claim 2 , wherein the cooling module includes a heat sink having a plurality of heat dissipating elements.

11. The heater assembly of claim 10 , wherein the cooling module further includes first and second cooling blocks enclosing the heat sink, the first and second cooling blocks being thermally conductive, and wherein at least one of the first and second cooling blocks has a port providing liquid for cooling the heat sink.

12. The heater assembly of claim 11 , further comprising a resilient seal circumferentially surrounding the heat sink between the first and second cooling blocks for sealing liquid in the cooling module.

13. The heater assembly of claim 2 , further comprising a sample holder assembly configured to magnetically hold a sample disk containing the sample, wherein the sample holder assembly and the heating module abut one another, and wherein the sample holder assembly is in axial alignment with the heating and cooling modules, and wherein the drift is drift in z (orthogonal to a surface of the sample).

14. The heater assembly of claim 13 , wherein the sample holder assembly and the heating and cooling modules have a combined weight of less than 3 grams.

15. A Scanning Probe Microscope (SPM), comprising:
a base;
a bridge structure coupled to and supported by the base;
a z-axis actuator coupled to the bridge structure;
a head assembly coupled to the z-axis actuator, the head assembly including an atomic force probe; and
a low drift heater assembly supported by the base, the low drift heater assembly including:
a sample holder assembly configured to magnetically hold a sample disk containing a sample to be scanned;
a heating module providing a heat source; and
a cooling module for cooling the heat source,
wherein the sample holder assembly and the heating and cooling modules are in axial alignment, and
wherein the heating and cooling modules are simultaneously active to control heat transfer through the axial alignment to the sample to be scanned.

16. The SPM of claim 15 , wherein the heating and cooling modules are controlled in closed-loop control systems.

17. The SPM of claim 15 , wherein the heat transfer is operable to heat the sample to be scanned to at least 250 degrees Celsius in less than 5 seconds.

18. The SPM of claim 15 , wherein the heat transfer is operable to maintain a temperature of the sample to be scanned to within ±0.001 degree Celsius.

19. A low drift heating method for a metrology instrument, the method comprising:
providing a heating module for generating a heat source;
providing a cooling module for cooling the heat source;
abutting the heating and cooling modules to one another in axial alignment; and
simultaneously activating the heating and cooling modules to control heat transfer through the axial alignment to a sample to be scanned.

20. The low drift heating method of claim 19 , further comprising controlling the heating and cooling modules in at least one closed-loop control system.

Assignees

• Bruker Nano Inc

Inventors

• Neushul Andrew
• Ruiter Anthonius

Classifications

• G01Q30/06

  for error compensation · CPC title

• G01Q30/10 Primary

  Thermal environment · CPC title

• G01Q20/02

  by optical means · CPC title