Pattern transfer printing systems and methods
Pattern transfer printing (PTP) systems and methods are provided to improve the quality, accuracy and throughput of pattern transfer printing. PTP systems comprise a tape handling unit for handling a tape with pattern transfer sheets sections and for controllably delivering the pattern transfer sheets one-by-one for paste filling and consecutively for pattern transfer, with the tape moving from an unwinder roll to a re-winding roll. PTP systems further comprise a paste filling unit which enables continuous paste filling using a supporting counter roll opposite to the paste filling head, a wafer handling and positioning unit controllably delivering wafers for the pattern transfer in a parallelized manner that increases throughput, a paste transfer unit with enhanced accuracy and efficiency due to exact monitoring and wafer alignment, as well as a print quality control unit.
1 . A pattern transfer printing (PTP) system comprising:
a tape handling unit configured to handle a tape comprising, as sections thereof, a plurality of pattern transfer sheets having respective patterns of trenches, and to controllably deliver the pattern transfer sheets for paste filling and consecutively for pattern transfer,
a paste filling unit configured to fill the trenches on the delivered pattern transfer sheets with conductive printing paste,
a wafer handling and positioning unit configured to controllably deliver at least one wafer for the pattern transfer at a close proximity to the respective pattern transfer sheet,
a paste transfer unit configured to transfer the conductive printing paste from the pattern transfer sheets filled with the conductive printing paste onto the wafer delivered in position, by releasing the conductive printing paste from the trenches upon illumination by a laser beam,
wherein the tape handling unit is configured to move the tape from an unwinder roll to a re-winding roll in a step-and-repeat mode,
wherein the wafer handling and positioning unit comprises at least one stage enabling movement in x and z axes, each of the at least one stage comprising at least one holder, with each of the at least one holder supporting a respective at least one wafer and enabling wafer movement in y, 0 axes, and
wherein the at least one holder comprises protrusions configured to support a margin of the respective wafer, and the wafer handling and positioning unit comprises a set of belts configured to accommodate the protrusions during vertical movements of the holder.
2 . The PTP system of claim 1 , wherein the paste filling unit comprises moveable paste filling head and a countering moveable roll configured to support a back side of the pattern transfer sheet during the paste filling.
3 . The PTP system of claim 1 , wherein the paste filling unit is set at an angle in the range of 0-30° relative to the vertical axis.
4 . The PTP system of claim 1 , further comprising a pattern transfer unit configured to control the illumination of the paste-filled trenches on the transfer sheet by the laser beam.
5 . The PTP system of claim 4 , wherein the illumination of the paste-filled trenches is done one-by-one by help of an optical head enabling fast laser scanning along a machine direction (MD) and movable along a cross-machine direction (CMD).
6 . The PTP system of claim 1 , further comprising a tape stretching unit configured to affix and flatten the respective pattern transfer sheet during the pattern transfer.
7 . The PTP system of claim 1 , further comprising a print quality control unit configured to detect defects of the transferred pattern on wafers.
8 . A pattern transfer printing (PTP) system comprising:
a tape handling unit configured to handle a tape comprising, as sections thereof, a plurality of pattern transfer sheets having respective patterns of trenches, and to controllably deliver the pattern transfer sheets for paste filling and consecutively for pattern transfer,
a paste filling unit configured to fill the trenches on the delivered pattern transfer sheets with conductive printing paste,
a wafer handling and positioning unit configured to controllably deliver at least one wafer for the pattern transfer at a close proximity to the respective pattern transfer sheet,
a paste transfer unit configured to transfer the conductive printing paste from the pattern transfer sheets filled with the conductive printing paste onto the wafer delivered in position, by releasing the conductive printing paste from the trenches upon illumination by a laser beam,
wherein the tape handling unit is configured to move the tape from an unwinder roll to a re-winding roll in a step-and-repeat mode, and
wherein the PTP system further comprises a trench alignment monitoring unit configured to monitor a position and a distortion of the trenches prior to the pattern transfer.
9 . The PTP system of claim 8 , wherein the trench alignment monitoring unit comprises multiple imaging cameras configured to capture ends of the trenches and at least two tilted imaging cameras configured to capture at least middle-sections of the trenches, wherein the tilt is with respect to a vertical direction and is configured to capture the middle-sections of the trenches.
10 . The PTP system of claim 8 , further comprising a tape stretching unit configured to affix and flatten the respective pattern transfer sheet during the pattern transfer, wherein the tape stretching unit comprises along a cross-machine direction (CMD), two opposing stretching units configured to affix and stretch corresponding tape edges.
11 . The PTP system of claim 8 , wherein the tape handling unit is further configured to deliver the pattern transfer sheets one-by-one for the paste filling and/or for the pattern transfer.
12 . The PTP system of claim 8 , wherein the paste filling unit comprises moveable paste filling head and a countering moveable roll configured to support a back side of the pattern transfer sheet during the paste filling.
13 . The PTP system of claim 8 , wherein the paste filling unit is set at an angle in the range of 0-30° relative to the vertical axis.
14 . The PTP system of claim 8 , further comprising a pattern transfer unit configured to control the illumination of the paste-filled trenches on the transfer sheet by the laser beam.
15 . The PTP system of claim 14 , wherein the illumination of the paste-filled trenches is done one-by-one by help of an optical head enabling fast laser scanning along a machine direction (MD) and movable along a cross-machine direction (CMD).
16 . The PTP system of claim 8 , further comprising a wafer alignment unit configured to detect and measure features on the wafer and further adjust the wafer position in the pattern transfer unit accordingly.
17 . The PTP system of claim 8 , further comprising a print quality control unit configured to detect defects of the transferred pattern on wafers.
18 . A pattern transfer printing (PTP) system comprising:
a tape handling unit configured to handle a tape comprising, as sections thereof, a plurality of pattern transfer sheets having respective patterns of trenches, and to controllably deliver the pattern transfer sheets for paste filling and consecutively for pattern transfer,
a paste filling unit configured to fill the trenches on the delivered pattern transfer sheets with conductive printing paste,
a wafer handling and positioning unit configured to controllably deliver at least one wafer for the pattern transfer at a close proximity to the respective pattern transfer sheet,
a paste transfer unit configured to transfer the conductive printing paste from the pattern transfer sheets filled with the conductive printing paste onto the wafer delivered in position, by releasing the conductive printing paste from the trenches upon illumination by a laser beam,
wherein the tape handling unit is configured to move the tape from an unwinder roll to a re-winding roll in a step-and-repeat mode, and
wherein the PTP system further comprises a wafer alignment unit configured to detect and measure features on the wafer and further adjust the wafer position in the pattern transfer unit accordingly, wherein the wafer alignment unit comprises multiple imaging cameras configured to capture at least a part of a perimeter of the wafer.
19 . The PTP system of claim 18 , wherein the cameras are further configured to image the wafer corners and features at a middle of the wafer.
20 . The PTP system of claim 18 , wherein the wafer alignment unit comprises a single high-resolution imaging camera with a corresponding high-resolution lens, configured to capture a full perimeter of the wafer.
21 . The PTP system of claim 18 , wherein the paste filling unit comprises moveable paste filling head and a countering moveable roll configured to support a back side of the pattern transfer sheet during the paste filling.
22 . The PTP system of claim 18 , wherein the paste filling unit is set at an angle in the range of 0-30° relative to the vertical axis.
23 . The PTP system of claim 18 , further comprising a pattern transfer unit configured to control the illumination of the paste-filled trenches on the transfer sheet by the laser beam.
24 . The PTP system of claim 23 , wherein the illumination of the paste-filled trenches is done one-by-one by help of an optical head enabling fast laser scanning along a machine direction (MD) and movable along a cross-machine direction (CMD).
25 . The PTP system of claim 18 , further comprising a trench alignment monitoring unit configured to monitor a position and a distortion of the trenches prior to the pattern transfer.
26 . The PTP system of claim 25 , wherein the trench alignment monitoring unit comprises multiple imaging cameras configured to capture ends of the trenches and at least two tilted imaging cameras configured to capture at least middle-sections of the trenches, wherein the tilt is with respect to a vertical direction and is configured to capture the middle-sections of the trenches.
27 . The PTP system of claim 18 , further comprising a tape stretching unit configured to affix and flatten the respective pattern transfer sheet during the pattern transfer wherein the tape stretching unit comprises along a cross-machine direction (CMD), two opposing stretching units configured to affix and stretch corresponding tape edges.
28 . The PTP system of claim 18 , further comprising a print quality control unit configured to detect defects of the transferred pattern on wafers.
29 . A pattern transfer printing (PTP) method comprising:
handling a tape comprising, as sections thereof, a plurality of pattern transfer sheets having respective patterns of trenches, to controllably deliver the pattern transfer sheets for paste filling and consecutively for pattern transfer,
filling the trenches on the delivered pattern transfer sheets with conductive printing paste,
controllably delivering a plurality of wafers for the pattern transfer, and
transferring the conductive printing paste from the pattern transfer sheets onto the delivered wafers, by releasing the conductive printing paste from the trenches upon illumination by a laser beam,
wherein the handling of the tape comprises moving the tape from an unwinder roll to a re-winding roll in a step-and-repeat mode, and
wherein the PTP method further comprises monitoring of the positions of the trenches prior to the pattern transfer using multiple imaging cameras configured to capture ends of the trenches.
30 . The PTP method of claim 29 , further comprising at least one of:
monitoring a tension and a position of the tape,
cleaning the pattern transfer sheets after the pattern transfer to provide reusable pattern transfer sheets,
supporting a back side of the pattern transfer sheet by a countering moveable roll during the paste filling,
affixing and flattening the pattern transfer sheet during the pattern transfer,
monitoring positions of the trenches prior to the pattern transfer,
detecting and measuring features on the wafer and adjusting accordingly the transferring of the conductive printing paste from the pattern transfer sheets onto the delivered wafers, and
inspecting a quality of the transferred paste pattern.
31 . The PTP method of claim 29 , comprising the affixing and flattening the pattern transfer sheet along a cross-machine direction (CMD) by two opposing stretching units.
32 . The PTP method of claim 29 , further comprising monitoring distortions of the trenches prior to the pattern transfer using at least two tilted imaging cameras configured to capture at least middle-sections of the trenches, wherein the tilt is with respect to the vertical direction and is configured to capture the middle-sections of the trenches.
33 . The PTP system of claim 29 , further comprising a tape stretching unit configured to affix and flatten the respective pattern transfer sheet during the pattern transfer wherein the tape stretching unit comprises along a cross-machine direction (CMD), two opposing stretching units configured to affix and stretch corresponding tape edges.