Methods and systems for thermal-based laser processing a multi-material device

• US 7,382,389 B2
• Filed: 11/07/2006
• Issued: 06/03/2008
• Est. Priority Date: 03/29/2001
• Status: Expired due to Fees

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: GSI Lumonics Corporation (Novanta Inc.)
• Inventors: Smart, Donald V., Ehrmann, Jonathan S., Johnson, Shepard D., Cordingley, James J., Svetkoff, Donald J., Lee, Joohan, Filgas, David M.
• Primary Examiner(s): PHAM, HAI CHI
• Application Number:
  US11/593,797
• Publication Number:
  US 20070052791A1
• Time in Patent Office: 574 Days
• Field of Search: 2191216-12169, 347224-225, 347/237, 347/247, 438/7
• US Class Current: 347/224
• CPC Class Codes: B23K 2101/38 Conductors
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/10 Aluminium or alloys thereof
• CPC Class Codes: B23K 2103/12 Copper or alloys thereof
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/043 along the beam path, i.e. alignment of laser beam axis relative to laser beam apparatus
• CPC Class Codes: B23K 26/0613 having a common axis B23K26/0619 takes precedence
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0643 comprising mirrors
• CPC Class Codes: B23K 26/0648 comprising lenses
• CPC Class Codes: B23K 26/0652 comprising prisms
• CPC Class Codes: B23K 26/0665 by beam condensation on the workpiece, e.g. for focusing
• CPC Class Codes: B23K 26/067 Dividing the beam into multiple beams, e.g. multifocusing
• CPC Class Codes: B23K 26/0736 into an oval shape, e.g. elliptic shape
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/10 : using a fixed support , i.e. involving moving the laser beam
• CPC Class Codes: B23K 26/16 : Removal of by-products, e.g. particles or vapours produced during treatment of a workpiece by a fluid stream B23K26/142
• CPC Class Codes: B23K 26/361 : for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/389 : of fluid openings, e.g. nozzles, jets laser machining of inkjet nozzles B41J2/1634
• CPC Class Codes: B23K 26/40 : taking account of the properties of the material involved
• CPC Class Codes: H01L 21/485 : Adaptation of interconnections, e.g. engineering charges, repair techniques
• CPC Class Codes: H01L 21/76888 : By rendering at least a portion of the conductor non conductive, e.g. oxidation
• CPC Class Codes: H01L 21/76894 : using a laser, e.g. laser cutting, laser direct writing, laser repair
• 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 23/5258 : the change of state resulting from the use of an external beam, e.g. laser beam or ion beam
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 3/0026 : by laser ablation

Abstract

A method and system for locally processing a predetermined microstructure formed on a substrate without causing undesirable changes in electrical or physical characteristics of the substrate or other structures formed on the substrate are provided. The method includes providing information based on a model of laser pulse interactions with the predetermined microstructure, the substrate and the other structures. At least one characteristic of at least one pulse is determined based on the information. A pulsed laser beam is generated including the at least one pulse. The method further includes irradiating the at least one pulse having the at least one determined characteristic into a spot on the predetermined microstructure. The at least one determined characteristic and other characteristics of the at least one pulse are sufficient to locally process the predetermined microstructure without causing the undesirable changes.

Claims

1. A method for thermal-based laser processing a multi-material device including a substrate and a microstructure, the method comprising:

generating two or more laser pulses having at least one predetermined characteristic based on a differential thermal property of materials of the device; and

irradiating the microstructure with the two or more laser pulses wherein a first pulse increases a difference in temperature between the substrate and the microstructure and wherein a second pulse further increases the difference in temperature between the substrate and the microstructure to process the multi-material device without damaging the substrate;

wherein the pulses are spaced such that the temperature of the substrate decays rapidly and stabilizes during a time between irradiation of the microstructure with a pair of pulses of said two or more laser pulses, and wherein the two or more pulses irradiate the microstructure during relative motion between the microstructure and a laser beam path associated with the pulses.

2. The method as claimed in claim 1 wherein the first pulse increases the temperature of the microstructure.

3. The method as claimed in claim 2 wherein the second pulse further increases the temperature of the microstructure.

4. The method as claimed in claim 1 wherein at least one pulse has a rise time of less than two nanoseconds.

5. The method as claimed in claim 4 wherein the rise time is less than one nanosecond.

6. The method as claimed in claim 1 wherein the first and second pulses are sufficient to remove the microstructure.

7. The method as claimed in claim 1 wherein the microstructure is a metal link having reflectivity and wherein the leading edge of at least one pulse reduces the reflectivity of the metal link.

8. The method as claimed in claim 7 wherein the substrate is silicon and the device is a semiconductor memory.

9. The method of claim 1 wherein the difference in temperature between the substrate and the microstructure increases during the time between irradiation of the microstructure with the first and second pulses.

10. The method of claim 1 wherein the first and second pulses are separated by between 8 and 20 nanoseconds.

11. A system for thermal-based laser processing a multi-material device including a substrate and a microstructure, the system comprising:

means for generating two or more laser pulses having at least one predetermined characteristic based on a differential thermal property of materials of the device; and

means for irradiating the microstructure with the two or more laser pulses wherein a first pulse increases a difference in temperature between the substrate and the microstructure and wherein a second pulse further increases the difference in temperature between the substrate and the microstructure to process the multi-material device without damaging the substrate;

wherein the temperature of the substrate decays rapidly and stabilizes during the time between irradiation of the microstructure with a pair of pulses of said two or more laser pulses, and wherein the two or more pulses irradiate the microstructure during relative motion between the microstructure and a laser beam path associated with the pulses.

12. The system as claimed in claim 11 wherein the first pulse increases the temperature of the microstructure.

13. The system as claimed in claim 12 wherein the second pulse further increases the temperature of the microstructure.

14. The system as claimed in claim 11 wherein at least one pulse has a rise time of less than two nanoseconds.

15. The system as claimed in claim 14 wherein the rise time is less than one nanosecond.

16. The system as claimed in claim 11 wherein the first and second pulses are sufficient to remove the microstructure.

17. The system as claimed in claim 11 wherein the microstructure is a metal link having reflectivity and wherein the leading edge of at least one pulse reduces the reflectivity of the metal link.

18. The system as claimed in claim 17 wherein the substrate is silicon and the device is a semiconductor memory.

19. The system of claim 11 wherein the difference in temperature between the substrate and the microstructure increases during the time between irradiation of the microstructure with the first and second pulses.

20. The system of claim 11 wherein the first and second pulses are separated by between 8 and 20 nanoseconds.