Method and apparatus for predicting a growth rate of deposited contaminants

Patent metadata

Field	Value
Publication number	US-9506881-B2
Application number	US-201214345656-A
Country	US
Kind code	B2
Filing date	Sep 19, 2012
Priority date	Sep 19, 2011
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A lithography system ( 10 ) comprising a radiation projection system ( 20 ) for projecting radiation onto a substrate, a substrate transport system ( 30 ) for loading and positioning the substrate to be processed in the path of the projected radiation, a control system ( 40 ) for controlling the substrate transport system to move the substrate, and a resist characterization system ( 50 ) arranged for determining whether a specific type of resist is suitable to be exposed by radiation within the lithography system. The resist characterization system ( 50 ) may be arranged for exposing the resist on a surface of the substrate with one or more radiation beams, measuring a mass distribution of molecular fragments emitted from the resist, predicting a growth rate of deposited molecular fragments on the basis of a growth rate model and the measured mass distribution, and comparing the expected growth rate with a predetermined threshold growth rate.

First claim

The invention claimed is:

1. A lithography system comprising:
a radiation projection system for projecting radiation onto a substrate;
a substrate transport system for loading and positioning the substrate to be processed in the path of the projected radiation;
a control system for controlling the substrate transport system to move the substrate; and
a resist characterization system arranged for determining whether a specific type of resist is suitable to be exposed by radiation within the lithography system;

wherein the resist characterization system is arranged for:
exposing the resist on a surface of the substrate with one or more radiation beams;
measuring a mass distribution of molecular fragments emitted from the resist;
using a growth rate model, based on earlier measurements of radiation induced deposition caused by known molecular fragments for different partial pressures;
predicting a growth rate of deposited molecular fragments on the basis of the growth rate model of molecular fragments and the measured mass distribution of molecular fragments, and deriving a partial pressure on the basis of the measured mass distribution of molecular fragments; and
comparing the predicted growth rate with a predetermined threshold growth rate, the threshold growth rate being related to a maximum allowable growth rate in the lithography system.

2. The system of claim 1 , wherein the radiation takes the form of one or more charged particle beamlets, and wherein the earlier measurements of radiation induced deposition are performed for different current densities of the one or more charged particle beamlets.

3. The system of claim 1 , wherein the radiation projection system comprises a beamlet generator for generating a plurality of beamlets, a beamlet modulator for patterning the beamlets to form modulated beamlets, and a beamlet projector for projecting the modulated beamlets onto a surface of the substrate.

4. The system of claim 1 , wherein the resist characterization system is coupled to the substrate transport system for transferring a substrate to the lithographic system for lithographic exposure.

5. The system of claim 1 , wherein the resist characterization system comprises a chamber, a pump system arranged for pumping down the chamber to lower the pressure in the chamber; a radiation source for generating one or more radiation beams, a substrate provided with a resist layer on the surface, and a measurement device.

6. The system of claim 5 , wherein the measurement device provides a resist outgas mass distribution.

7. The system of claim 5 , wherein the measurement device comprises a residual gas analyzer.

8. A method for determining suitability of a resist for use in a lithography system, the method comprising:
providing a substrate having the resist on a surface of the substrate;
exposing the resist with one or more radiation beams;
measuring a mass distribution of molecular fragments emitted from the resist;
predicting a growth rate of deposited molecular fragments on the basis of a growth rate model of molecular fragments and the measured mass distribution of molecular fragments, the model being based on earlier measurements of radiation induced deposition caused by known molecular fragments for different partial pressures; and
comparing the predicted growth rate with a predetermined threshold growth rate, the threshold growth rate being related to a maximum allowable growth rate in the lithography system.

9. The method of claim 8 , wherein the radiation takes the form of one or more charged particle beamlets, and wherein the earlier measurements of radiation induced deposition are performed for different current densities of the one or more charged particle beamlets.

10. The method of claim 8 , wherein predicting the growth rate of deposited molecular fragments is further based on a geometry factor, the geometry factor being representative of the influence of one or more properties of the lithography system.

11. The method of claim 10 , wherein the geometry factor is representative of the influence of the geometry of the lithography system on the growth rate of the deposition.

12. The method of claim 8 , wherein the model includes growth rates for a plurality of different molecular fragments.

13. The method of claim 8 , wherein the model includes growth rates for different intensities of the radiation beam.

14. The method of claim 8 , wherein deriving the partial pressure comprises summation using the measured mass distribution of the molecular fragments.

15. A method for predicting a growth rate of deposited contaminants resulting from deposition of gaseous contaminants outgassed from a substance undergoing processing by one or more radiation beams, the method comprising:
exposing the substance with the one or more radiation beams;
measuring a mass distribution of molecules and molecular fragments of the contaminants emitted from the substance;
predicting a growth rate of deposited molecules and molecular fragments of the contaminants on the basis of a growth rate model and the measured mass distribution of molecular fragments, the model being based on earlier measurements of radiation induced deposition caused by known molecular fragments for different partial pressures; and
comparing the predicted growth rate with a predetermined threshold growth rate, the threshold growth rate being related to a maximum allowable growth rate in the lithography system.

16. An apparatus for predicting a growth rate of deposited contaminants resulting from deposition of gaseous contaminants outgassed from a substance undergoing processing by one or more radiation beams, the apparatus comprising:
a chamber;
a pump system arranged for pumping down the chamber to lower the pressure in the chamber;
a radiation source for generating the one or more radiation beams;
a substrate provided with the substance on a surface of the substrate;
a measurement device for measuring a mass distribution of the gaseous contaminants outgassed from a substance; and
a processor configured to predict a growth rate of the deposited contaminants on the basis of a growth rate model of molecular fragments and the measured mass distribution of molecular fragments, the model being based on earlier measurements of radiation induced deposition caused by known molecular fragments for different partial pressures.

Assignees

• Mapper Lithography Ip Bv

Inventors

• Smits Marc

Classifications

• G01N33/0004

  Gaseous mixtures, e.g. polluted air · CPC title

• H01J2237/31796

  affecting resists · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• H01J37/304

  Controlling tubes by information coming from the objects {or from the beam}, e.g. correction signals · CPC title

• G03F7/70916

  Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps · CPC title