Method and system for laser soft marking

1. A laser-marking method of marking a semiconductor wafer to form a softmark on the wafer, the method comprising:

setting a laser pulse width of one or more laser pulses to selectively provide one or more laser output pulses having one or more set pulse widths that affect the depth of a softmark that is to be formed, the mark depth to be substantially dependent on the one or more set pulse widths;

setting a pulse energy of the one or more output pulses to selectively provide the one or more output pulses having a set total output energy that is within an acceptable process energy window for producing the softmark;

delivering the one or more output pulses having the one or more set pulse widths and the set total output energy into a region of the wafer such that energy density within the region, as determined by the one or more set pulse widths and the set total output energy, modifies wafer material and thereby produces the softmark having a raised annular rim and a recessed center with the mark depth within a predetermined range wherein the softmark is debris free; and

controllably resetting the laser pulse width without substantially changing the energy density to change the mark depth within the predetermined range wherein the mark depth is controllably adjusted and wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

2. The method as claimed in claim 1 , wherein the steps of setting are performed substantially simultaneously.

3. The method as claimed in claim 1 , wherein the mark depth is in the range of about 1 micron to 6 microns.

4. The method as claimed in claim 1 , wherein the mark depth is predetermined and formed with exactly one output pulse.

5. The method as claimed in claim 1 , wherein the mark depth is finer than about 1 micron.

6. The method as claimed in claim 1 , wherein an output pulse has a set pulse width in the range of about 10 nanoseconds to about 200 nanoseconds.

7. The method as claimed in claim 1 , wherein the step of setting the laser pulse width is performed subsequent to the step of setting the pulse energy.

8. The method as claimed in claim 1 , wherein the step of setting the pulse energy is performed subsequent to the step of setting the laser pulse width.

9. A laser-marking system for marking a semiconductor wafer to form a softmark on the wafer, the system comprising:

a laser subsystem for generating one or more laser pulses;

a controller operatively connected to the laser subsystem to:

set a laser pulse width of the one or more laser pulses to selectively provide one or more laser output pulses having one or more set pulse widths that affect the depth of a softmark that is to be formed, the mark depth to be substantially dependent on the one or more set pulse widths;

set a pulse energy of the one or more output pulses to selectively provide the one or more output pulses having a set total output energy that is within an acceptable process energy window for producing the softmark; and

controllably reset the pulse width without substantially changing the energy density to change the mark depth wherein the mark depth is controllably adjusted; and

a beam delivery system that includes an optical subsystem for delivering the one or more output pulses having the one or more set pulse widths and the set total output energy into a region of the wafer such that energy density within the region, as determined by the one or more set pulse widths and the set total pulse energy, modifies wafer material and thereby produces the softmark having a raised annular rim and a recessed center with the mark depth within a predetermined range wherein the softmark is debris free and wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

10. The system as claimed in claim 9 , wherein the controller includes a subsystem of electronic components and a control program that is generally used for marking system control.

11. The system as claimed in claim 9 , wherein the controller includes a subsystem of electronic components and a control program that is dedicated to control of the laser subsystem.

12. The system as claimed in claim 9 , wherein the laser subsystem includes a fiber-based laser having a tunable pulse width.

13. A laser-marking method of forming a softmark on a semiconductor wafer, the method comprising:

setting one or more laser pulse widths of one or more laser pulses, the one or more set pulse widths affecting depth of the softmark to be formed with the one or more laser pulses;

setting total output energy of the one or more laser pulses, the set total output energy corresponding to energy within an acceptable process energy window to form the softmark on the semiconductor wafer, the softmark having a raised annular rim and a recessed center with the mark depth and wherein the softmark is debris free; and

controllably resetting the one or more laser pulse widths without substantially changing the energy density to change the depth of the softmark wherein the mark depth is controllably adjusted and wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

14. A laser-marking method of forming softmarks having a raised annular rim and different predetermined recessed center depths on semiconductor wafers, the method comprising:

setting a laser pulse width or a burst width of one or more laser pulses, the set pulse width or set burst width corresponding to a desired depth of a softmark to be formed with the one or more laser pulses;

setting total output energy of the one or more laser pulses;

setting total output energy of the one or more laser pulses to a value within a process energy window to form a softmark having the desired depth on the semiconductor wafer;

forming the softmark having the desired depth on a semiconductor wafer with the one or more laser pulses, the softmark having a raised annular rim and a recessed center with the desired depth wherein the softmark is debris free;

controllably resetting the laser pulse width or burst width to change the mark depth based on a determined dependence of the softmark depth on the laser pulse width or burst width; and

forming a softmark having a different depth on a semiconductor wafer wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

15. A laser-marking method of forming a softmark on a semiconductor wafer, the method comprising:

setting a temporal characteristic of at least a portion of a pulsed laser output that affects depth of a softmark to be formed with the laser output, the softmark having a raised annular rim and a recessed center with the mark depth and wherein the softmark is debris free;

setting total output energy of the pulsed laser output to correspond to energy within an acceptable process energy window so as to form the softmark on the semiconductor wafer; and

controllably resetting the temporal characteristic without substantially changing the energy density to change the mark depth wherein the mark depth is controllably adjusted and wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

16. The method as claimed in claim 15 , further comprising marking a batch of wafers with the softmarks, and wherein the temporal characteristic and the total output energy remain set during marking of the entire batch.

17. The method as claimed in claim 15 , further comprising positioning a wafer at a marking station prior to marking a single wafer with softmarks.

18. The method as claimed in claim 15 , further comprising positioning a wafer at a marking station prior to marking a single wafer with softmarks, and wherein the temporal characteristic and the total output energy are varied to produce softmarks having different predetermined depths on the wafer.

19. The method as claimed in claim 15 , wherein the steps of setting are performed by a laser-marking system user interface or control program and wherein the temporal characteristic corresponds to softmark depth and the acceptable process energy window is predetermined.

20. A laser-marking method of marking a semiconductor wafer to form a softmark having a raised annular rim and a variable recessed center depth on the wafer, the method comprising:

selecting a desired softmark depth within a softmark depth range, the selected depth corresponding to a predetermined laser pulse width or burst width for a given energy density;

setting one of a laser pulse width of a single pulse or a burst width of a sequence of pulses to selectively provide one or more laser output pulses having a set pulse width or a set burst width corresponding to the desired softmark depth;

setting a total energy output of the one or more output pulses to selectively provide the one or more output pulses having a set total output energy that is within a process energy window for producing the softmark having the desired softmark depth; and

delivering the one or more output pulses having the set pulse width or the set burst width and the set total output energy into a region of the wafer such that energy density within the region, as determined by the set total output energy, modifies wafer material and thereby produces the softmark having a raised annular rim and a recessed center with the desired softmark depth wherein the softmark is debris free and wherein the desired softmark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

21. The method as claimed in claim 20 , wherein the mark depth is in the range of about 1 micron to 6 microns.

22. The method as claimed in claim 21 , wherein the mark depth range is 1.8 microns to 2.6 microns corresponding to respective pulse widths of 72 ns to 124 ns.

23. The method as claimed in claim 20 , wherein the mark depth is predetermined and formed with exactly one output pulse.

24. The method as claimed in claim 20 , wherein the mark depth is finer than about 1 micron.

25. The method as claimed in claim 20 , wherein diameter of the softmark is about 48 microns to about 64 microns.

26. The method as claimed in claim 20 , wherein energy within the process energy window varies by a ratio of less than 2:1.

27. The method as claimed in claim 20 , wherein an output pulse has a typical set pulse width in the range of about 10 nanoseconds to about 200 nanoseconds.

28. A laser-marking system for marking a semiconductor wafer to form a softmark having a raised annular rim and a variable recessed center depth on the wafer, the system comprising:

a laser subsystem for generating one or more laser pulses with a settable pulse width or a settable burst width in a predetermined range of values corresponding to a predetermined range of softmark depths;

a controller operatively connected to the laser subsystem to:

receive data corresponding to a desired softmark depth within the predetermined range of softmark depths;

set a laser pulse width or burst width of the one or more laser pulses to selectively provide one or more laser output pulses having a set pulse width or a set burst width corresponding to the desired softmark depth; and

set a pulse energy of the one or more output pulses to selectively provide the one or more output pulses having a set total output energy that is within a process energy window for producing the softmark; and

a beam delivery system that includes an optical subsystem for delivering the one or more output pulses having the set pulse width or set burst width and the set total output energy into a region of the wafer such that energy density within the region, the set total pulse energy modifies wafer material and thereby produces the softmark having a raised annular rim and a recessed center with the desired softmark depth wherein the softmark is debris free and wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

29. The system as claimed in claim 28 , wherein the controller includes a subsystem of electronic components and a control program that is generally used for marking system control.

30. The system as claimed in claim 28 , wherein the controller includes a subsystem of electronic components and a control program that is dedicated to control of the laser subsystem.

31. The system as claimed in claim 28 , further comprising:

a user interface operable to select at least one of a mark depth, a laser pulse width corresponding to a mark depth, and laser output energy.

32. The system as claimed in claim 28 , wherein the laser subsystem includes a fiber-based laser having tunable pulse width.

33. A laser-marking method of forming softmarks having a raised annular rim and different predetermined recessed center depths on semiconductor wafers, the method comprising:

setting a temporal characteristic of at least a portion of a pulsed laser output that corresponds to a desired depth of a softmark to be formed with the laser output;

setting total output energy of the pulsed laser output to a value within a process energy window for producing the softmark having the desired depth;

forming the softmark having the desired depth on a semiconductor wafer with the laser output, the softmark having a raised annular rim and a recessed center with the desired depth and wherein the softmark is debris free;

controllably resetting the temporal characteristic to change the mark depth based on a determined dependence of the softmark depth on the temporal characteristic; and

forming a softmark having a different depth on the semiconductor wafer wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.

34. The method as claimed in claim 33 , wherein the temporal characteristic is one of a pulse width, a burst width, a burst envelope shape, a burst duration, a temporal spacing between bursts, a temporal spacing between two or more pulses, a temporal overlap between two or more pulses, a delay between two or more pulses, and a pulse shape.

35. The method as claimed in claim 33 , further comprising marking a batch of wafers with the softmarks, and wherein the temporal characteristic and the total output energy remain set during marking of the entire batch.

36. The method as claimed in claim 35 , further comprising:

positioning each wafer in the batch at a marking station.

37. The method as claimed in claim 33 , wherein the temporal characteristic and the total output energy are varied to produce softmarks having different predetermined depths.

38. The method as claimed in claim 33 , wherein the step of setting are performed by a laser-marking system and wherein the temporal characteristic and the total output energy are set using a user interface of the laser-marking system.

39. A laser-marking method of forming a softmark having a raised annular rim and a variable recessed center depth on a semiconductor wafer, the method comprising:

setting a temporal characteristic of at least a portion of a pulsed laser output that corresponds to a desired depth of a softmark to be formed with the laser output;

setting total output energy of the pulsed laser output to correspond to energy within a process energy window so as to form the softmark on the semiconductor wafer; and

forming the softmark having the desired depth on a semiconductor wafer, the softmark having a raised annular rim and a recessed center wherein the softmark is debris free; wherein the steps of setting and the step of forming are performed by a laser-marking system and wherein the temporal characteristic and the total output energy are set using a user interface of the laser-marking system wherein the mark depth is substantially proportional to a pulse width over a substantial range of pulse widths;

wherein energy in a single output pulse is in a range of about 600 microjoules to about 1100 microjoules; and

wherein the acceptable process energy window is centered on a central energy in a range having a lower limit of about 10 microjoules less than the central energy and an upper limit about 10 microjoules above the central energy and wherein diameter of the softmark is about 48 microns or greater.