# US 11,910,537 B2 · Pattern transfer printing systems and methods

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- Number: US 11,910,537 B2
- Document ID: US11910537B2
- Status: Granted
- Kind: B2
- Application number: 17/583,440
- Filed: 2022-01-25
- Published: 2023-05-11
- Granted: 2024-02-20
- Earliest claimed: 2021-11-09
- Assignees: Wuhan DR Laser Technology Corp,. LTD
- Applicants: Wuhan Dr Laser Technology Corp., Ltd.
- Inventors: Gad Igra; Eyal Cohen; Eran Yunger; Moshe Finarov; Tao Xu; Jing Shi; Weiguo Tong; Zhigang Li
- Web page: https://patentgrep.com/patent/US11910537B2

## CPC

- H10F 71/00: Manufacture or treatment of devices covered by this subclass (patterning processes to connect thin photovoltaic cells in integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/33; manufacture or treatment of encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/80; manufacture or treatment of integrated devices, or assemblies of multiple devices, comprising at least one element in which radiation controls the flow of current H10F39/00)
- H10F 77/211: {for photovoltaic cells}
- B41J 2/442: {using lasers}
- B41J 2/47: using the combination of scanning and modulation of light
- B41J 2/475: for heating selectively {by radiation or ultrasonic waves}
- H05K 1/092: {Dispersed materials, e.g. conductive pastes or inks}
- H05K 1/11: Printed elements for providing electric connections to or between printed circuits
- H05K 3/107: {by filling grooves in the support with conductive material (H05K3/045, H05K3/101, H05K3/1258 and H05K3/465 take precedence)}
- H05K 3/1258: {by using a substrate provided with a shape pattern, e.g. grooves, banks, resist pattern}
- H05K 3/1275: {by other printing techniques, e.g. letterpress printing, intaglio printing, lithographic printing, offset printing}
- H05K 2203/0113: Female die used for patterning or transferring, e.g. temporary substrate having recessed pattern
- H05K 2203/0156: Temporary polymeric carrier or foil, e.g. for processing or transferring
- H05K 2203/107: Using laser light
- H05K 2203/1545: Continuous processing, i.e. involving rolls moving a band-like or solid carrier along a continuous production path
- H05K 2203/166: Alignment or registration; Control of registration
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

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 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.

## Claims

### Claim 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 unit configured to controllably deliver at least one wafer for the pattern transfer at a close proximity to the 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 PTP system further comprises at least one of:
a trench alignment monitoring unit configured to monitor a position and a distortion of the trenches prior to the pattern transfer, 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; and/or
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, the cameras configured to image the wafer corners and features at a middle of the wafer.

### Claim 2 (depends on 1)

The PTP system of claim 1, 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.

### Claim 3 (depends on 1)

The PTP system of claim 1, wherein the tape handling unit further comprises at least one top dancer and at least one bottom dancer configured to maintain a tension of the tape continuously.

### Claim 4 (depends on 1)

The PTP system of claim 1, further comprising a tape re-use unit configured to clean the pattern transfer sheets after the pattern transfer to provide reusable pattern transfer sheets.

### Claim 5 (depends on 4)

The PTP system of claim 4, wherein the tape re-use unit further comprises at least one dancer and/or rolls configured to maintain a tension of the tape moving through the tape re-use unit.

### Claim 6 (depends on 4)

The PTP system of claim 4, wherein the tape re-use unit comprises a pre-cleaning compartment for removing clumps of paste, a cleaning compartment configured to remove fine paste remains and a drying unit for drying the tape prior to rolling the tape onto the re-winding roll.

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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.

### Claim 9 (depends on 1)

The PTP system of claim 1, wherein the wafer handling 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 the at least one wafer and enabling wafer movement in y, θ axes.

### Claim 10 (depends on 1)

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.

### Claim 11 (depends on 10)

The PTP system of claim 10, 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).

### Claim 12 (depends on 1)

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.

### Claim 13 (depends on 1)

The PTP system of claim 1, comprising the trench alignment monitoring unit having the multiple imaging cameras configured to capture the ends of the trenches and the at least two tilted imaging cameras configured to capture the at least middle-sections of the trenches.

### Claim 14 (depends on 1)

The PTP system of claim 1, comprising the wafer alignment unit having the multiple imaging cameras configured to capture at least the part of the perimeter of the wafer, the cameras configured to image the wafer corners and features at the middle of the wafer.

### Claim 15 (depends on 1)

The PTP system of claim 1, further comprising a print quality control unit configured to detect defects of the transferred pattern on wafers.

### Claim 16 (depends on 1)

A dual lane production line comprising two PTP systems of claim 1, set back-to-back with the respective unwinder roll and re-winding roll of each of the PTP system accessible for maintenance.

### Claim 17

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 the 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 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
wherein the method further comprises at least one of:
monitoring positions and distortions of the trenches prior to the pattern transfer using 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; and/or
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, using multiple imaging cameras configured to capture at least a part of a perimeter of the wafer, the cameras configured to image the wafer corners and features at a middle of the wafer.

### Claim 18 (depends on 17)

The PTP method of claim 17, 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, and
inspecting a quality of the transferred paste pattern.

### Claim 19 (depends on 17)

The PTP method of claim 17, further comprising carrying out the PTP method using two PTP systems arranged back-to-back in a dual lane production line, with parallel wafer delivery and with the tape and the unwinder roll and re-winding roll accessible for replacement and maintenance from a front side of each of the PTP systems.

### Claim 20 (depends on 17)

The PTP method of claim 17, comprising the monitoring of the positions and distortions of the trenches prior to the pattern transfer using the multiple imaging cameras configured to capture ends of the trenches and the 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.

### Claim 21 (depends on 17)

The PTP method of claim 17, comprising the detecting and measuring of the features on the wafer and adjusting accordingly the transferring of the conductive printing paste from the pattern transfer sheets onto the delivered wafers, using multiple imaging cameras configured to capture at least the part of the perimeter of the wafer, the cameras configured to image the wafer corners and features at the middle of the wafer.