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

• US 8,999,628 B1
• Filed: 06/09/2014
• Issued: 04/07/2015
• 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 G
• Application Number:
  US14/299,891
• Time in Patent Office: 302 Days
• Field of Search: 430/30, 430/296, 430/314, 430/942
• US Class Current: 430/296
• 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 method of writing resist-coated substrates using charged particle beams, comprising the actions of:

writing multiple cut features specified by a design layout database onto at least one substrate;

etching said substrate using etch parameters;

imaging said features, said features being targeted in at least partial dependence on the design layout database;

automatically identifying one or more defects in ones of said features in at least partial dependence on said imaging and the design layout database;

automatically modifying at least one of said etch parameters, in at least partial dependence on said identifying; and

repeating at least said writing and said etching using said modified etch parameters;

wherein said writing and said imaging use multiple charged particle beams produced by multiple columns that are substantially the same, different ones of said beams targeting different portions of the substrate; and

wherein the stages on which the substrate is mounted during said writing and said imaging are substantially the same.

2. The method 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 method of claim 1, wherein successive iterations of said repeating either use the substrate and said writing is used to repair said defects, or use successively different substrates.

4. The method of claim 1, wherein said writing writes said features onto the resist layer coated on the surface of the substrate, said resist being sensitive to charged particle beam exposure;

further comprising developing said written resist to form layout features on said substrate;

wherein said imaging images said layout features.

5. The method of claim 1, wherein said identifying compares said layout feature images to said features specified by the design layout database.

6. The method of claim 1, wherein said identifying determines which of said defects comprise process-induced defects, and wherein said modifying modifies the etch parameters to reduce the likelihood of producing said process-induced defects upon said repeating said writing.

7. The method of claim 1, wherein stage movements and beam deflections used to target said features in said writing and said imaging are the same, except for separate per-column beam alignment offsets for said writing and said imaging, said offsets determined prior to said writing and said imaging, respectively.

8. The method of claim 1, wherein said identifying compares the design layout database to images resulting from said imaging.

9. The method of claim 1, wherein said imaging and said identifying are each performed after both etching the substrate and developing the substrate;

wherein said imaging, said identifying, and said etching are performed on at least one iteration of said repeating; and

wherein said identifying after said developing designates at least some of said defects identified after said developing for imaging at a higher resolution after said repeated etching.

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

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

12. The method of claim 10, wherein said controllers perform at least some of said identifying.

13. The method of claim 1, wherein successive iterations of said writing, imaging, identifying, modifying and repeating steps are performed using successively modified said etch parameters, whereby in successive iterations said defects are stochastically reduced.

14. The method of claim 1, wherein said identifying comprises determining locations and classifying defect types of said defects.

15. The method of claim 14, wherein said identifying further comprises classifying 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.

16. The method of claim 14, wherein said modifying only modifies said etch parameters with respect to ones of said defects of a type likely to cause yield loss.

17. The method 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.

18. The method of claim 1, wherein beam deflection parameters for beam targeting in said writing and imaging are determined in at least partial dependence on the design layout database.

19. The method of claim 1, wherein said modifying is performed in at least partial dependence on iterations of said identifying step from prior to previous iterations of said repeating step.

20. The method of claim 1, wherein said writing is performed while varying parameters comprising at least one of beam energy, beam focus, exposure time and beam current;

wherein said identifying determines which of said defects are reduced by varying said parameters; and

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

21. The method of claim 1, wherein the substrate is written using optical lithography prior to said writing step.

22. The method of claim 1, wherein both said writing and said imaging are performed differently and simultaneously by different ones of said beams.

23. The method of claim 1, wherein said imaging and said identifying are performed on a substrate both after develop and after etch, and wherein one or more care areas are designated for increased-resolution after develop imaging in at least partial dependence on defects identified by said after etch identifying.

24. The method of claim 1, wherein one or more iterations of said imaging are performed while varying parameters comprising at least one of beam energy, beam focus, exposure time and beam current;

wherein said identifying determines which of said varied parameters improve defect detection sensitivity; and

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