Method for laser scribing of wafers

• US 6,555,447 B2
• Filed: 03/27/2001
• Issued: 04/29/2003
• Est. Priority Date: 06/08/1999
• Status: Expired due to Fees

• Current Assignee: Advanced Dicing Technologies Ltd. (GL Tech Co., Ltd.)
• Original Assignee: Kulicke & Soffa Investments, Inc.
• Inventors: Weishauss, Ilan, Wertheim, Oded, Manor, Ran
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Le, Thao P
• Application Number:
  US09/817,959
• Publication Number:
  US 20010054606A1
• Time in Patent Office: 763 Days
• Field of Search: 438/460, 438/461, 438/462, 438/465
• US Class Current: 438/460
• CPC Class Codes: B23K 2101/35 Surface treated articles
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B28D 1/221 by thermic methods
• CPC Class Codes: B28D 5/0011 with preliminary treatment, e.g. weakening by scoring
• CPC Class Codes: B28D 5/022 by cutting with discs or wheels
• CPC Class Codes: B28D 5/029 with a plurality of cutting blades
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: H01S 5/0201 Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth

Abstract

A method for laser scribing a semiconductor substrate with coatings on top. The method comprises the steps of focusing a laser beam on a top surface of the substrate coating; absorbing energy from the laser into the coating layer; forming a first set of scribe lines in a first direction on the substrate by scanning the laser beam across the surface of the substrate to evaporate portions of the coating layer; and forming a second set of scribe lines in a second direction on the surface of the substrate substantially orthogonal to the first set of scribe lines to evaporate portions of the layer.

Claims

1. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to a wavelength of the laser beam;

(b) absorbing energy from the laser beam into the layer based on the first absorption coefficient;

(c) forming at first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer; and

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser beam, the second direction substantially orthogonal to the first direction,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient by about an order of magnitude.

2. The method according to claim 1, wherein the laser emits infrared radiation.

3. The method according to claim 2, wherein the wavelength of the laser is between about 1.2 and 15 microns.

4. The method according to claim 2, wherein the wavelength of the laser is between about 9 and 11 microns.

5. The method according to claim 2, wherein the wavelength of the laser is one of i) 9.3, ii) 9.6 and iii) 10.6 microns.

6. The method according to claim 1, wherein the layer is a plurality of layers and the second absorption coefficient of the substrate is less than each respective absorption coefficient of the plurality of layers.

7. The method according to claim 6, wherein the plurality of layers includes one or more of i) a passivation layer, ii) a polyimide layer, iii) a silicon oxide compound, iv) a silicon nitride compound, v) a dielectric layer, vi) aluminum and vii) copper.

8. The method according to claim 1, further comprising the step of:

e) dicing the substrate along the first set and second set of scribe lines to form a plurality of dice.

9. The method according to claim 8, wherein said step (e) further comprises the steps of:

(e1) sawing the substrate along the first set of scribe lines with a dicing saw to form a respective first set of kerfs;

(e2) sawing the substrate along the second set of scribe lines with the dicing saw to form a respective second set of kerfs.

10. The method according to claim 9, wherein a width of the laser scribe lines is greater than that of the saw blade kerfs.

11. The method according to claim 1, wherein each one of said first set of scribe lines is substantially parallel to one another, and each one of said second set of scribe lines is substantially parallel to one another.

12. The method according to claim 1, wherein the laser beam is formed by a CO2 laser.

13. The method according to claim 1, wherein the scribe lines have a depth equal to a depth of the layer.

14. The method according to claim 1, wherein the scribe lines have a depth no greater than a depth of the layer.

15. The method according to claim 1, wherein the substrate is silicon and the layer over the substrate is other than silicon.

16. The method according to claim 1, wherein the second absorption coefficient is less than the first absorption coefficient by at least an order of magnitude.

22. The method according to claim 1, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.

17. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam having a wavelength between about 1.2 and 15 microns at a layer placed over a top surface of the substrate, the layer having a first absorption coefficient relative to the wavelength of the laser beam;

(b) absorbing energy from the laser beam into the layer based on the first absorption coefficient;

(c) forming at first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer; and

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser beam, the second direction substantially orthogonal to the first direction,

wherein the substrate has a second absorption coefficient relative to the wavelength of the laser beam, the second absorption coefficient less than the first absorption coefficient by about an order of magnitude.

18. The method according to claim 17, wherein the second absorption coefficient is less than the first absorption coefficient by at least an order of magnitude.

19. A method for dicing a semiconductor substrate comprising the steps of:

(a) aiming a laser beam at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser beam into only the layer;

(c) forming at first set of scribe lines in a first direction in the layer by scanning the laser beam across the layer, the laser beam removing at least a portion of the layer; and

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser beam across the layer and removing at least a portion of the layer with the laser, the second direction substantially orthogonal to the first direction,

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength from the laser beam, the first absorption coefficient greater than the second absorption coefficient.

20. The method according to claim 19, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.

21. A method for dicing a semiconductor substrate using a laser and a dicing saw, the method comprising the steps of:

(a) aiming the laser at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser into the layer;

(c) forming at first set of scribe lines in a first direction in the layer by scanning the laser across the layer, the laser removing at least a portion of the layer;

(d) forming a second set of scribe lines in a second direction in the layer by scanning the laser across the layer and removing at least a portion of the layer with the laser, the second direction substantially orthogonal to the first direction;

(e) cutting a first set of kerfs in the substrate with the dicing saw along the first set of scribe lines; and

(f) cutting a second set of kerfs in the substrate with the dicing saw along the second set of scribe lines,

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength of the laser beam, the first absorption coefficient greater than the second absorption coefficient by about an order of an order of magnitude, and the first set of kerfs and said second set of kerfs form a plurality of dice from the substrate.

23. A method for dicing a semiconductor substrate using a laser and a dicing saw, the method comprising the steps of:

(a) aiming the laser at a layer placed over a top surface of the substrate;

(b) absorbing energy from the laser into the layer;

(c) forming a first scribe line in a first direction in the layer by scanning the laser across the layer, the laser removing at least a portion of the layer;

(d) cutting a first kerf in the substrate with the dicing saw along the first scribe line;

(e) forming a further first scribe line in the first direction over the substrate, the further scribe line substantially parallel to the first scribe line;

(f) cutting a further first kerf in the substrate with the dicing saw along the further first scribe line;

(g) repeating steps (e) and (f) in the first direction until the entire substrate is scribed and cut;

(h) forming a second scribe line in a second direction in the layer by scanning the laser across the layer and removing at least a portion of the layer, the second direction substantially orthogonal to the first direction;

(i) cutting a second kerf in the substrate with the dicing saw along the second scribe line;

(j) forming a further second scribe line in the second direction on the substrate, the further second scribe line substantially parallel to the second scribe line;

(k) cutting a further second kerf in the substrate with the dicing saw along the further second scribe line; and

(1) repeating steps (j) and (k) in the second direction until the entire substrate is scribed and cut;

wherein the layer has a first absorption coefficient and the substrate has a second absorption coefficient relative to a wavelength of the laser beam, the first absorption coefficient greater than the second absorption coefficient by about an order of magnitude, and the first kerf, the further first kerfs, the second kerf and the further second kerfs form a plurality of dice from the substrate.

24. The method according to claim 23, wherein the first absorption coefficient is greater than the second absorption coefficient by at least an order of magnitude.