Automatic optimization of etch process for accelerated yield ramp with matched charged particle multi-beam systems

• US 9,207,539 B1
• Filed: 01/28/2015
• Issued: 12/08/2015
• Est. Priority Date: 03/05/2013
• Status: Active Grant

• Current Assignee: Multibeam Corporation
• Original Assignee: Multibeam Corporation
• Inventors: Lam, David K., Monahan, Kevin M., Prescop, Theodore A., Tran, Cong
• Primary Examiner(s): Young, Christopher
• Application Number:
  US14/607,821
• Time in Patent Office: 314 Days
• Field of Search: 430/30, 430/296, 430/314, 430/942, 250/492.2, 250/492.23, 250/492.3
• US Class Current: 1/1
• CPC Class Codes: G03F 7/2051 Exposure without an original mask, e.g. using a programmed deflection of a point source, by scanning, by drawing with a light beam, using an addressed light or corpuscular source G03F7/70 takes precedence
• CPC Class Codes: G03F 7/2059 using a scanning corpuscular radiation beam, e.g. an electron beam
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36
• CPC Class Codes: H01J 2237/04 Means for controlling the discharge
• CPC Class Codes: H01J 2237/049 Focusing means
• CPC Class Codes: H01J 2237/1501 Beam alignment means or procedures
• CPC Class Codes: H01J 2237/24592 Inspection and quality control of devices
• CPC Class Codes: H01J 2237/30416 Handling of data for lithography H01J37/3174
• CPC Class Codes: H01J 2237/30472 Controlling the beam
• CPC Class Codes: H01J 2237/31761 Patterning strategy
• CPC Class Codes: H01J 2237/31774 Multi-beam
• CPC Class Codes: H01J 2237/31798 detecting pattern defects with SEM H01J2237/2817; correcting H01J2237/31735, H01J2237/3174
• CPC Class Codes: H01J 37/30 Electron-beam or ion-beam tubes for localised treatment of objects
• CPC Class Codes: H01J 37/3005 Observing the objects or the point of impact on the object
• CPC Class Codes: H01J 37/304 Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
• CPC Class Codes: H01J 37/3174 Particle-beam lithography, e.g. electron beam lithography
• CPC Class Codes: H01J 37/3177 Multi-beam, e.g. fly's eye, comb probe
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps

Abstract

The present application discloses methods, systems and devices for using charged particle beam tools to pattern and inspect a substrate. The inventors have discovered that it is highly advantageous to use write and inspection tools that share the same or substantially the same stage and the same or substantially the same designs for respective arrays of multiple charged particle beam columns, and that access the same design layout database to target and pattern or inspect features. By using design-matched charged particle beam tools, correlation of defectivity is preserved between inspection imaging and the design layout database. As a result, image-based defect identification and maskless design correction, of random and systematic errors, can be performed directly in the design layout database, enabling a fast yield ramp.

Claims

1. A system for writing resist-coated substrates using charged particle beams, comprising:

at least one lithography tool, and at least one inspection tool, said lithography tool and said inspection tool both comprising;

a substrate stage;

multiple charged particle beam columns, ones of said columns being configured to produce a charged particle beam, different ones of said beams targeting different corresponding portions of the substrate; and

one or more beam controllers, configured to control said columns to write cut features to the substrate in said lithography tool, and configured to control said columns to image said features in said inspection tool, said features being specified by a design layout database;

an etch tool configured to remove material, from the portions of the substrate written by said lithography tool, in at least partial dependence on etch parameters;

an inspection data analyzer, configured to receive said feature images from said columns, and to automatically identify one or more defects in ones of said features in at least partial dependence on said feature images and the design layout database; and

an etch parameter modifier, configured to automatically modify said etch parameters in at least partial dependence on said identified defects;

wherein said lithography tool and said inspection tool comprise substantially the same substrate stage and substantially the same columns, and the same design layout database is used by said lithography tool and said inspection tool.

2. The system of claim 1, wherein said etch parameters comprise one or more of:

temperature, pressure, total duration, gas flow rate, gas mixture, duration of different etch phases, and electromagnetic field strength.

3. The system of claim 1, wherein said lithography tool is configured to write said features onto the resist layer coated on the surface of the substrate, said resist being sensitive to charged particle beam exposure;

further comprising a developing tool configured to develop said written resist to form layout features on said substrate;

wherein said imaging images said layout features.

4. The system of claim 3, wherein said inspection data analyzer is configured to compare said layout feature images to said features specified by the design layout database.

5. The system of claim 1, wherein said etch parameter modifier reduces the likelihood of said writing using said modified etch parameters resulting in said defects.

6. The system of claim 1, wherein said inspection data analyzer is configured to determine which of said defects comprise process-induced defects, and wherein said etch parameter modifier is configured to modify said etch parameters to reduce the likelihood of producing said process-induced defects upon said repeating said writing.

7. The system of claim 1, wherein said lithography tool and said inspection tool are configured to use the same stage movements and beam deflections to target said features, except for separate per-column beam alignment offsets for said writing and said imaging, and wherein said beam controllers are configured to determine said offsets prior to said writing and said imaging, respectively.

8. The system of claim 1, wherein said lithography tool and said inspection tool are the same tool or separate tools.

9. The system of claim 1, wherein said inspection data analyzer is configured to compare the design layout database to images resulting from said imaging.

10. The system of claim 1, wherein different ones of multiple controllers are local to and are configured to control different corresponding ones of said columns, and wherein said controllers are configured to store the portion of the design layout database targeted by said corresponding ones of said columns.

11. The system of claim 10, wherein said controllers are configured to only store the portion of the design layout database targeted by said corresponding ones of said columns.

12. The system of claim 10, wherein said controllers are configured to perform at least some of said identifying.

13. The system of claim 1, wherein said inspection data analyzer is configured to determine locations and classify defect types of said defects.

14. The system of claim 13, wherein said inspection data analyzer is configured to classify ones of said defects in at least partial dependence on how likely said defects are to cause yield loss caused by deviations in parametric performance or failure of device function.

15. The system of claim 13, wherein said etch parameter modifier is configured to modify said etch parameters only with respect to ones of said defects of a type likely to cause yield loss.

16. The system of claim 1, wherein said charged particle beams are electron beams, said columns are miniature columns using electrostatic deflection to target the substrate, and said stages are configured to have substantially the same substrate-stage alignment mechanisms, stage positioning mechanisms, stage position accuracy, and control electronics and software.

17. The system of claim 1, wherein said lithography tool and said inspection tool are configured to respectively determine beam deflection parameters for beam targeting in said writing and said imaging in at least partial dependence on the design layout database.

18. The system of claim 1, wherein said lithography tool is configured to perform said write while varying parameters comprising at least one of beam energy, beam focus, exposure time and beam current;

wherein said inspection data analyzer determines which of said defects are reduced by varying said parameters; and

wherein said modifier varies said parameters to reduce said defects and thereby increase yield.

19. The system of claim 1, further comprising an optical tool configured to write the substrate using optical lithography prior to said lithography tool writing the substrate using charged particle beam lithography.

20. The system of claim 1, wherein said beam controllers are configured to control different ones of said columns to perform said writing and said imaging, in said lithography tool and said inspection tool respectively, differently and simultaneously.

21. The system of claim 1, wherein ones of said beam controllers are configured to control said columns in said inspection tool to perform said image while varying parameters comprising at least one of beam energy, beam focus, exposure time and beam current;

wherein said inspection data analyzer determines which of said varied parameters improve defect detection sensitivity; and

wherein said modifier varies said parameters to enhance said defect detection sensitivity and thereby increase yield.