Methods and systems for precisely relatively positioning a waist of a pulsed laser beam and method and system for controlling energy delivered to a target structure
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.
1. A method for precisely relatively positioning a waist of a pulsed laser material processing beam to compensate for microscopic positional variations of predetermined target material to be laser processed, the target material being supported on a semiconductor substrate, the method comprising:
obtaining three-dimensional information at a plurality of predetermined locations about the target material, the locations being a combination of at least one predetermined location at which an alignment target is formed and at least one other predetermined location at which an alignment target is not formed and which is suitable for an optical measurement;
predicting the location of the target material relative to a laser beam waist position based on the three-dimensional information including three-dimensional information obtained at the at least one other predetermined location to obtain a three-dimensional location prediction;
inducing motion of the target material relative to a laser beam waist position based on the prediction;
generating a laser beam including at least one pulse; and
irradiating the at least one pulse into a spot on the target material to process the target material.
2. The method of claim 1 , wherein the target material is a redundant memory link and wherein the substrate comprises a silicon substrate.
3. The method of claim 1 , further comprising updating the prediction during motion of the target material relative to the laser beam waist position, the step of updating including obtaining three-dimensional information at at least one of an alignment target location and other predetermined location suitable for an optical measurement.
4. The method of claim 3 , wherein the step of updating is carried out, at least in part, with an astigmatic dynamic focus sensor.
5. The method of claim 1 , wherein the step of obtaining is carried out, at least in part, with an astigmatic dynamic focus sensor.
6. The method of claim 1 , wherein the step of obtaining includes measuring height of a portion of the semiconductor substrate.
7. The method of claim 6 , wherein the portion of semiconductor substrate is covered with at least one oxide layer, and wherein the step of measuring height is substantially polarization insensitive.
8. The method of claim 1 , wherein the beam waist has a dimension in the range of about less than about 1.8 microns, and wherein a plurality of short pulses are irradiated into the spot.
9. The method of claim 1 , further comprising:
determining, prior to the step of irradiating, a reference surface, other than a surface of the semiconductor substrate that supports the target material, so as to obtain predetermined reference surface information, the reference surface corresponding to a support surface configured to support the semiconductor substrate; wherein the step of predicting is based on the predetermined reference surface information in combination with the three-dimensional information, thereby reducing total position variation associated with misalignment or other topographical variations that exceed a depth of focus corresponding to the beam waist, whereby laser increased speed of operation is obtainable over a substantially large portion of the substrate.
10. The method of claim 9 , wherein the step of determining the reference surface is carried out during a calibration process.
11. The method of claim 9 , wherein the reference surface is substantially planar, and wherein the reference surface corresponds to a chuck surface that supports the semiconductor substrate during the step of irradiating.
12. The method of claim 1 , wherein the three-dimensional information includes relative height at the locations about the target material.
13. The method of claim 1 , wherein the three-dimensional information obtained from the at least one alignment target location includes both a lateral position and height information.
14. The method of claim 13 , wherein the lateral position is obtained from at least one predetermined location at which an alignment target is formed.
15. A system for precisely relatively positioning a waist of a pulsed laser, material processing beam to compensate for microscopic positional variations of predetermined target material to be laser processed, the target material being supported on a semiconductor substrate, the system comprising:
means for obtaining three-dimensional information at a plurality of predetermined locations about the target material, the locations being a combination of at least one predetermined location at which an alignment target is formed and at least one other predetermined location at which an alignment target is not formed and which is suitable for an optical measurement;
means for predicting the location of the target material relative to a laser beam waist position based on the three-dimensional information to obtain a three-dimensional location prediction;
means for inducing motion of the target material relative to a laser beam waist position based on the prediction;
means for generating a laser beam including at least one pulse; and
means for irradiating the at least one pulse into a spot on the target material to process the target material.
16. The system of claim 15 , wherein the target material is a redundant memory link and wherein the substrate comprises a silicon substrate.
17. The system of claim 15 , further comprising means for updating the prediction during motion of the target material relative to the laser beam waist position, the means for updating including means for obtaining three-dimensional information at at least one of an alignment target location and other predetermined location suitable for an optical measurement.
18. The system of claim 17 , wherein the means for updating includes an astigmatic dynamic focus sensor.
19. The system of claim 15 , wherein the means for obtaining includes an astigmatic dynamic focus sensor.
20. The system of claim 15 , wherein the means for obtaining includes means for measuring height of a portion of the semiconductor substrate.
21. The system of claim 20 , wherein the portion of semiconductor substrate is covered with at least one oxide layer, and wherein the means for measuring height is substantially polarization insensitive.
22. The system of claim 15 , wherein the beam waist has a dimension in the range of about less than about 1.8 microns, and wherein a plurality of short pulses are irradiated into the spot.
23. The system of claim 15 , further comprising:
means for determining, prior to irradiating, a reference surface, other than a surface of the semiconductor substrate that supports the target material, so as to obtain predetermined reference surface information, the reference surface corresponding to a support surface configured to support the semiconductor substrate; wherein the prediction is based on the predetermined reference surface information in combination with the three-dimensional information, thereby reducing total position variation associated with misalignment or other topographical variations that exceed a depth of focus corresponding to the beam waist, whereby laser increased speed of operation is obtainable over a substantially large portion of the substrate.
24. The system of claim 23 , wherein the reference surface is determined during a calibration process.
25. The system of claim 23 , wherein the reference surface is substantially planar, and wherein the reference surface corresponds to a chuck surface that supports the semiconductor substrate during irradiation.
26. The system of claim 15 , wherein the three-dimensional information includes relative height at the locations about the target material.
27. The system of claim 15 , wherein the three-dimensional information includes both a lateral position and height information.
28. The system of claim 27 , wherein lateral position is obtained from at least one predetermined location at which an alignment target is formed.