Substrate processing with reduced warpage and/or controlled strain
View Patent ↗Provided are systems and methods for processing the surface of substrates that scan a laser beam at one or more selected orientation angles. The orientation angle or angles may be selected to reduce substrate warpage. When the substrates are semiconductor wafers having microelectronic devices, the orientation angles may be selected to produce controlled strain and to improve electronic performance of the devices.
1. A method for processing a surface of a substrate, comprising:
(a) mounting the substrate on a moveable stage;
(b) generating a photonic beam suitable for processing the substrate surface;
(c) adjusting the moveable stage to position the substrate at a first orientation angle relative to the beam;
(d) performing a first scanning of the beam translationally over the substrate surface along a first path at the first orientation angle relative to the beam; and
(e) following step (d) adjusting the movable stage to position the substrate at a second orientation angle relative to the beam; and
(f) following step (e), performing a second scanning of the beam translationally over the substrate surface along a second path at the second orientation angle relative to the beam.
2. The method of claim 1 , wherein the photonic beam illuminates no more than 5% of the substrate surface at one time.
3. The method of claim 1 , wherein the photonic beam is effective to heat an illuminated portion of the substrate surface at a rate of at least 1000° C. per second.
4. The method of claim 1 , wherein steps (b) and (c) is carried out to allow the beam to scan translationally over substantially the entire substrate surface at first and second orientation angles.
5. The method of claim 1 , wherein the first and second paths, when viewed from the first and second orientation angles, respectively, are substantially identical to each other.
6. The method of claim 5 , wherein each of the first and second paths include a plurality of parallel segments.
7. The method of claim 6 , wherein the parallel segments of each of the first and second paths are linear.
8. The method of claim 6 , wherein the parallel segments of each of the first and second paths are curved.
9. The method of claim 6 , wherein the parallel segments of the first and second paths on the substrate are spaced apart at a predetermined distance from each other so that the illuminated sections on the substrate along the parallel segments overlap.
10. The method of claim 9 , wherein the beam has an intensity profile and predetermined distance is selected according to the intensity profile.
11. The method of claim 10 , wherein the intensity profile has a peak intensity region and the predetermined distance is selected such that the peak intensity regions do not overlap.
12. The method of claim 1 , wherein steps (d) and (f) are performed at substantially identical scan rates.
13. The method of claim 1 , wherein one of steps (d) and (f) are carried out to allow the beam to scan translationally over substantially the entire substrate surface and the other of steps (d) and (f) is carried out to allow the beam to scan over only a selected portion of the substrate surface.
14. A method for processing a substrate to produce a desired substrate surface contour, comprising:
(a) mounting a substrate having a surface having an initial surface contour profile on a moveable stage;
(b) generating a photonic beam suitable for processing the substrate surface;
(c) adjusting the moveable stage to position the substrate at a first orientation angle relative to the beam;
(d) scanning the beam translationally over the substrate surface along a first path at the first orientation angle relative to the beam, thereby converting the initial surface contour of the substrate into intermediate surface contour;
(e) following step (d) adjusting the movable stage to position the substrate at a second orientation angle relative to the beam; and
(f) following step (e), performing a second scanning of the beam translationally over the substrate surface along a second path at the second orientation angle relative to the beam, thereby converting the intermediate surface contour into the desired surface contour.
15. A method for reshaping a substrate having a surface with a contour unsuitable for subsequent processing, comprising:
(a) mounting the substrate on a movable stage;
(b) generating a photonic beam suitable for thermally processing the substrate surface;
(c) adjusting the moveable stage to position the substrate at a selected orientation angle relative to the beam; and
(d) scanning the beam translationally over the substrate surface along a selected path and the selected orientation angle relative to the beam to reshape the surface of the substrate in a manner effective to convert the unsuitable surface contour into a contour suitable for subsequent processing.
16. A method for thermally processing a semiconductor substrate having a microelectronic circuit on a surface thereof, comprising:
(a) mounting the substrate on a movable stage;
(b) generating a photonic beam suitable for producing an elongate image suitable for thermally processing the substrate surface;
(c) adjusting the moveable stage to position the substrate at a selected orientation angle relative to the beam; and
(d) scanning the image translationally over the substrate surface at the selected orientation angle relative to the beam effective to produce a surface strain in a manner that enhances carrier mobility in the microelectronic circuit relative to carrier mobility of the circuit without the surface strain.
17. The method of claim 16 , wherein the microelectronic circuit comprises a PMOS transistor.
18. The method of claim 16 , wherein the microelectronic circuit comprises a NMOS transistor.