A laser-induced thin-layer slurry large-gap transfer morphology regulation method

Abstract

The application discloses a laser-induced thin-layer slurry large-gap transfer morphology regulation method, which comprises the following steps: coating uniform thin-layer slurry with different thicknesses on a donor substrate; making the thin-layer slurry face a receiving substrate, and controlling the distance between the bottom of the thin-layer slurry and the receiving substrate to be greater than or equal to 500 microns; focusing a high-energy-density laser beam on the interface between the donor substrate and the thin-layer slurry; realizing single-pulse laser-induced point trajectory processing through a high-scan-speed and high-repetition-frequency scanning galvanometer; and directly transferring and forming a single-point array with different diameters, surface areas, heights, volumes and cross-sectional morphologies by adjusting the thickness of the thin-layer slurry and the size of the transfer gap ratio (≤0.3; 0.3-0.1; ≥0.1). The application can directly regulate and form single-point arrays with different morphologies under a large transfer gap, greatly improves the transfer gap tolerance and transfer efficiency, and significantly reduces the test cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of laser application and microelectronic printing technology, and particularly relates to a laser-induced thin-layer paste large-gap transfer morphology control method. BACKGROUND

[0002] With the development of modern microelectronic printing industry towards miniaturization, thinness and high controllability, higher requirements are put forward for printing resolution and morphology control. How to quickly and efficiently realize micro-pattern printing of different morphologies has become an important challenge.

[0003] Laser direct writing technology is widely used in the preparation of micro-patterns in the field of microelectronic circuits. Laser-induced forward transfer technology (LIFT) is a new type of direct writing technology, which has the technical advantages of non-contact, mask-free, simple process and flexible control. In the research of laser-induced micro-pattern transfer forming technology, a method for controlling the geometric morphology of laser metallized grid lines is provided in Chinese patent ZL202211369655.7. By adjusting the matching relationship between the gap size between the conductive paste bottom and the solar cell piece and the laser beam energy density, the formed grid lines with different geometric morphologies are prepared. However, this method is only suitable for small transfer gaps (≤20 μm). Based on the transfer mechanism of laser-induced foaming driving thin-layer paste and the formation of paste bridge connection between the paste and the receiving substrate, the tolerance of the transfer gap is low. Chinese patent CN112382676B discloses a solar cell grid line laser-induced printing method based on a silicon wafer double-groove structure. Microstructures are pre-prepared on the receiving substrate to control the geometric morphology of the paste and the receiving substrate. However, this method increases the processing procedures.

[0004] The above-mentioned laser-induced micro-pattern transfer mainly focuses on the following two aspects for the control method of the formed morphology: first, under small transfer gap, the paste and the receiving substrate are contacted in the form of paste bridge, and the laser energy density is matched to realize the morphology control; second, microstructures are pre-prepared on the donor or receiving substrate to restrict the geometric morphology of the paste transfer or deposition. However, the control tolerance of the transfer gap is strict for small-gap transfer, and the separation process of the paste bridge and the receiving substrate increases the instability of the formed morphology control. On the other hand, the pre-preparation of microstructures increases the procedures and cost, and reduces the production efficiency. Therefore, it is urgent to seek a flexible control method for the formed morphology under large transfer gap. SUMMARY

[0005] To solve the above technical problems, the present application provides a laser-induced thin-layer slurry large-gap transfer morphology control method, which belongs to a direct control method of film thickness gap ratio on transfer morphology under large-gap transfer conditions, and a laser-induced high-efficiency forming single-point array with different diameters, surface areas, heights, volumes and cross-sectional morphologies. The present application first coats a uniform thin-layer slurry with different thicknesses on a donor substrate; and makes the thin-layer slurry face the receiving substrate, controls the transfer gap, i.e. the distance between the bottom of the thin-layer slurry and the receiving substrate, to be greater than or equal to 100 microns; focuses a high-energy-density laser beam on the interface between the donor substrate and the thin-layer slurry; realizes single-pulse laser-induced point trajectory processing through a high-scan-speed and high-repetition-frequency scanning galvanometer; and directly transfers and forms a single-point array with different diameters, surface areas, heights, volumes and cross-sectional morphologies by adjusting the thickness of the thin-layer slurry and the transfer gap ratio (≤0.3; 0.3-0.1; ≥0.1). The present application can directly control the formation of single-point arrays with different morphologies under a large transfer gap, greatly improves the transfer gap tolerance and transfer efficiency, and significantly reduces the test cost.

[0006] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0007] A laser-induced thin-layer slurry large-gap transfer morphology control method, comprising the following steps:

[0008] Step 1: preparing a uniform thin-layer slurry on a transparent donor substrate;

[0009] Step 2: placing the transparent donor substrate coated with the thin-layer slurry and the receiving substrate to be printed on a high-precision displacement platform, so that the position of the receiving substrate is fixed; making the thin-layer slurry face the receiving substrate and be located directly above the receiving substrate; and adjusting the distance between the bottom of the thin-layer slurry and the receiving substrate to be a transfer gap l, which is greater than or equal to 500 microns;

[0010] Step 3: making the pulsed laser emit a single-pulse laser, which is focused on the interface between the transparent donor substrate and the thin-layer slurry through a beam shaping module, a scanning galvanometer and a telecentric field lens;

[0011] Step 4: using the scanning galvanometer to make the single-pulse laser transmit through the transparent donor substrate and realize induced point trajectory processing at different positions of the thin-layer slurry;

[0012] Step 5: the single-pulse laser induces the bottom of the thin-layer slurry to produce a protrusion through foaming, and under a transfer gap l greater than or equal to 500 microns, the thin-layer slurry is transferred in the form of a jet and deposited and formed on the receiving substrate to directly transfer and form a single-point array;

[0013] Step 6, by adjusting the ratio of the thickness of the thin layer paste and the transfer gap, i.e. the film thickness gap ratio, the single point array with different diameters, surface areas, heights, volumes and cross-sectional morphologies is directly controlled to be formed at a transfer gap l greater than or equal to 500 μm.

[0014] Step 7, the printed single point array is dried, and the morphology of the formed point is observed by a laser scanning confocal microscope or a scanning electron microscope, and the diameter, surface area, height and volume of the formed point and the cross-sectional morphology are measured.

[0015] Further, in the step 1, the thin layer paste is a non-Newtonian fluid with shear thinning rheological properties, and the viscosity is 20-50 Pa·s, the particle size of the thin layer paste is ≤3 μm, and the minimum thickness of the thin layer paste is greater than or equal to 5 times the particle size of the thin layer paste.

[0016] Further, the thin layer paste is a conductive silver paste.

[0017] Further, the step 4 includes setting the processing parameters of the pulsed laser and the scanning galvanometer corresponding to the transfer of the thin layer paste with different thicknesses.

[0018] Further, the energy density of the single pulse laser is controlled to be 0.27-0.88 J / cm 2 , the repetition frequency is greater than or equal to 300 kHz, the speed of the scanning galvanometer is greater than or equal to 3000 mm / s, and the repetition frequency is greater than or equal to 3 kHz.

[0019] Further, the distance between the adjacent two points in the transferred and formed single point array is 1 mm.

[0020] Further, in the step 6, the control of the film thickness gap ratio includes three types, the first type of film thickness gap ratio is ≤0.03, the second type of film thickness gap ratio is 0.03-0.1, and the third type of film thickness gap ratio is ≥0.1.

[0021] Beneficial effects:

[0022] (1) The present application utilizes laser-induced non-contact transfer forming, and can directly control the transfer forming of single point arrays with different morphologies at a transfer gap greater than or equal to 500 μm, which is suitable for the development trend of miniaturization, thinness and high controllability of microelectronic circuit printing.

[0023] (2) In the small transfer gap, the laser-induced foaming drives the slurry to contact with the receiving substrate in the form of slurry bridge, and the laser energy density is matched to realize the morphology control or to preform the microstructure to constrain the slurry transfer or deposition geometry on the donor or receiving substrate. However, the present application utilizes the film thickness gap ratio to control the single-point array of different morphologies in the large transfer gap, thereby improving the transfer gap control tolerance, avoiding the influence of the slurry bridge and receiving substrate separation process on the forming morphology control, simplifying the pretreatment process, reducing the production cost, and improving the transfer efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the laser-induced thin-layer slurry large-gap transfer morphology control method of the present application.

[0025] Figure 2 is a system diagram of the laser-induced thin-layer slurry large-gap transfer forming device.

[0026] Figure 3 is a schematic diagram of the single-point array of the transfer forming.

[0027] Figure 4 is a schematic diagram of the 3-type film thickness gap ratio control of the diameter and surface area of the transfer point; wherein a is a schematic diagram of the change of the single-point diameter of the 3-type film thickness gap ratio transfer forming with energy density, and b is a schematic diagram of the change of the single-point surface area of the 3-type film thickness gap ratio transfer forming with energy density.

[0028] Figure 5 is a schematic diagram of the 3-type film thickness gap ratio control of the height and volume of the transfer point; wherein a is a schematic diagram of the change of the single-point height of the 3-type film thickness gap ratio transfer forming with energy density, and b is a schematic diagram of the change of the single-point volume of the 3-type film thickness gap ratio transfer forming with energy density.

[0029] Figure 6 is a schematic diagram of the 3-type film thickness gap ratio control of the surface and cross-sectional morphology of the transfer point.

[0030] Figure 7 is a schematic diagram of the single-point transfer morphology obtained in Example 1.

[0031] Figure 8 is a schematic diagram of the single-point transfer morphology obtained in Example 2.

[0032] Figure 9 is a schematic diagram of the single-point transfer morphology obtained in Example 3.

[0033] Wherein, the reference signs are: transparent donor substrate 1, thin-layer slurry 2, receiving substrate 3, high-precision displacement platform 4, pulsed laser 5, single-pulse laser 6, beam shaping module 7, scanning galvanometer 8, telecentric field lens 9, marble platform 10, single-point array 11. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0035] As shown in Figure 1 The laser-induced thin-layer paste large-gap transfer morphology control method of the present application comprises the following steps:

[0036] Step 1, a uniform thin-layer paste 2 is prepared on a transparent donor substrate 1 by using a horizontal doctor blade;

[0037] Preferably, the thickness h of the thin-layer paste 2 is 15-80 μm;

[0038] Preferably, the thin-layer paste 2 is a non-Newtonian fluid with shear thinning rheological properties, and the viscosity is 20-50 Pa·s. The thin-layer paste particle size is ≤3 μm, which ensures that the minimum thin-layer paste thickness is greater than or equal to 5 times the particle size of the thin-layer paste 2, and lays a foundation for the preparation of uniform thin-layer paste 2. Further, the thin-layer paste 2 can be conductive silver paste.

[0039] Step 2, the transparent donor substrate 1 coated with the thin-layer paste 2 and the receiving substrate 3 to be printed are placed on a high-precision displacement platform, the receiving substrate 3 is adsorbed by a vacuum chuck in the high-precision displacement platform 4 to fix the position of the receiving substrate 3; the thin-layer paste 2 is directed towards the receiving substrate 3 and located directly above the receiving substrate 3; the distance between the bottom of the thin-layer paste 2 and the receiving substrate 3 is the transfer gap l, and the transfer gap l is adjusted to be greater than or equal to 500 μm.

[0040] Step 3, the pulsed laser 5 is made to emit single-pulse laser 6, the single-pulse laser 6 passes through the beam shaping module 7, the scanning galvanometer 8 and the telecentric field lens 9, and is focused on the interface between the transparent donor substrate 1 and the thin-layer paste 2, and the whole system is placed on a high-precision marble platform 10, as shown in Figure 2 .

[0041] Step 4, the scanning galvanometer 8 is used to make the single-pulse laser 6 transmit through the transparent donor substrate 1 to realize induced point trajectory processing at different positions of the thin-layer paste 2.

[0042] The processing parameters of the pulsed laser 5 and the scanning galvanometer 8 are set, and the energy density of the single-pulse laser 6 is controlled at 0.27-0.88 J / cm 2, the repetition frequency is greater than or equal to 300 kHz. The speed of the scanning galvanometer 8 is greater than or equal to 3000 mm / s, and the repetition frequency is greater than or equal to 3 kHz. The speed and repetition frequency of the scanning galvanometer 8 jointly determine the spacing between adjacent points of the formed pattern, so the transfer efficiency can be improved by further increasing the speed and repetition frequency of the scanning galvanometer 8. The spacing between adjacent points in the transferred and formed single-point array 11 is 1 mm, as shown in Figure 3 .

[0043] Step 5, the single-pulse laser 6 induces the formation of protrusions at the bottom of the thin layer of paste 2 by foaming, as shown in Figure 3 , under a transfer gap l greater than or equal to 500 μm, the thin layer of paste 2 is transferred in the form of a jet and deposited on the receiving substrate 3 to form a pattern, and the transferred and formed single-point array 11 is directly transferred. Without the separation step of the paste bridge and the receiving substrate, the interference of this process on the formed pattern is reduced. Controlling the viscosity of the thin layer of paste 2 is the key to achieving transfer in the form of a jet under large gap conditions.

[0044] Step 6, by adjusting the ratio of the thickness of the thin layer of paste 2 to the transfer gap, i.e., the film thickness gap ratio, under a transfer gap l greater than or equal to 500 μm, the single-point array with different diameters, surface areas, heights, volumes, and cross-sectional morphologies can be directly controlled. Based on the results of a large number of experiments and process exploration, the control of the film thickness gap ratio mainly includes three types: the first type of film thickness gap ratio is ≤0.03; the second type of film thickness gap ratio is 0.03-0.1; and the third type of film thickness gap ratio is ≥0.1.

[0045] Step 7, the transferred single-point array to be printed is subjected to a drying treatment, and the morphology of the formed points is observed by a laser scanning confocal microscope or a scanning electron microscope, and the diameter, surface area, height, and volume of the formed points and the cross-sectional morphology are measured.

[0046] Specifically, by controlling the film thickness gap ratio to be 0.03, 0.04, 0.05, 0.06, 0.07, 0.1, 0.12, and 0.16, the diameter, height, surface area, and volume of the transferred single-point of the single-point array 11 and the cross-sectional morphology are controlled.

[0047] The diameter and surface area of the transferred single-point are controlled as follows: under an energy density of 0.27-0.88 J / cm 2 , the first type of film thickness gap ratio is ≤0.03, the diameter of the formed point is controlled to be 100-350 μm, and the surface area is controlled to be 1×10 4 ~8×10 4 μm 2 ; the second type of film thickness gap ratio is 0.03-0.1, the diameter of the formed point is controlled to be 130-200 μm, and the surface area is controlled to be 1×10 4 ~3×104 μm 2 ; the third type of film thickness gap ratio is greater than or equal to 0.1, the diameter of the point formed by regulation is 80-130 μm, and the surface area is 0.5*10 4 -1.5*10 4 μm 2 , as shown in Fig. 3a, wherein, Figure 4 a of Fig. 3a is a schematic diagram of the change of the diameter of the single point formed by the third type of film thickness gap ratio transfer with the energy density, Figure 4 b of Fig. 3a is a schematic diagram of the change of the surface area of the single point formed by the third type of film thickness gap ratio transfer with the energy density. Figure 4

[0048] The height and volume of the transferred single point are regulated, including: at 0.27-0.88 J / cm 2 energy density, the first type of film thickness gap ratio is less than or equal to 0.03, the height of the point formed by regulation is 8-18 μm, and the volume is 1*10 4 -4*10 4 μm 3 ; the second type of film thickness gap ratio is 0.03-0.1, the height of the point formed by regulation is 15-30 μm, and the volume is 5*10 4 -1.2*10 5 μm 3 ; the third type of film thickness gap ratio is greater than or equal to 0.1, the height of the point formed by regulation is 15-30 μm, and the volume is 2*10 4 -6*10 4 μm 3 , as shown in Fig. 3b, wherein, Figure 5 a of Fig. 3b is a schematic diagram of the change of the height of the single point formed by the third type of film thickness gap ratio transfer with the energy density, Figure 5 b of Fig. 3b is a schematic diagram of the change of the volume of the single point formed by the third type of film thickness gap ratio transfer with the energy density. Figure 5

[0049] The surface and cross-sectional morphology of the transferred single point are regulated, including: for the third type of film thickness gap ratio, when the laser energy density is equal to the critical transfer threshold, the morphology of the transferred single point presents a dome shape; when the laser energy density is greater than the critical transfer threshold, the morphology of the transferred single point presents a sharp tip shape, as shown in Fig. 3c, and the corresponding first type of film thickness gap ratio is less than or equal to 0.03, the transfer threshold is 0.31 J / cm 2 ; the second type of film thickness gap ratio is 0.03-0.1, the transfer threshold is 0.40 J / cm 2 ; the third type of film thickness gap ratio is greater than or equal to 0.1, and the transfer threshold is 0.62 J / cm 2 . Figure 6 Example 1:

[0050]

[0051] ​​​The laser-induced thin layer paste large gap transfer morphology regulation method of embodiment 1 comprises: in step 1, the thin layer paste 2 is conductive silver paste, the viscosity is 30 Pa·s, the thin layer paste particle size is 1 μm, and the thickness h of the thin layer paste is 15 μm; in step 2, the transfer gap between the bottom of the thin layer paste 2 and the receiving substrate 3 is 500 μm; in step 4, the scanning speed of the scanning galvanometer 8 is 3000 mm / s, the repetition frequency is 3 kHz, and the energy density of the single pulse laser 6 is 0.31-0.88 J / cm 2 ; in step 5, the transfer gap is 500 μm, and in step 6, the ratio of the thickness of the thin layer paste 2 to the transfer gap is 0.03, which belongs to the first type of film thickness gap ratio ≤0.3; as Figure 7 is a schematic diagram of the single-point transfer morphology of the regulation forming, the transfer threshold is 0.31 J / cm 2 , the diameter is 100-330 μm, the surface area is 1×10 4 -7×10 4 μm 2 , the height is 8-17 μm, and the volume is 1.5×10 4 -4×10 4 μm 3 .

[0052] Embodiment 2:

[0053] The laser-induced thin layer paste large gap transfer morphology regulation method of embodiment 2 comprises: in step 1, the thin layer paste 2 is conductive silver paste, the viscosity is 40 Pa·s, the thin layer paste particle size is 3 μm, and the thickness h of the thin layer paste is 50 μm; in step 2, the transfer gap between the bottom of the thin layer paste 2 and the receiving substrate 3 is 1000 μm; in step 4, the scanning speed of the scanning galvanometer 8 is 5000 mm / s, the repetition frequency is 5 kHz, and the energy density of the single pulse laser 6 is 0.44-0.88 J / cm 2 ; in step 5, the transfer gap is 1000 μm, and in step 6, the ratio of the thickness of the thin layer paste 2 to the transfer gap is 0.05, which belongs to the second type of film thickness gap ratio 0.03-0.1; as Figure 8 is a schematic diagram of the single-point transfer morphology of the regulation forming, the transfer threshold is 0.44 J / cm 2 , the diameter is 132-197 μm, the surface area is 1×10 4 -2.9×10 4 μm 2 , the height is 16-28 μm, and the volume is 5.5×10 4 -1.1×10 5 μm 3 .

[0054] Embodiment 3:

[0055] The laser-induced thin-layer paste large-gap transfer morphology regulation method of embodiment 3 includes: in step 1, the thin-layer paste 2 is conductive silver paste, the viscosity is 50 Pa·s, the thin-layer paste particle size is 2 μm, and the thickness h of the thin-layer paste is 80 μm; in step 2, the transfer gap between the bottom of the thin-layer paste 2 and the receiving substrate 3 is 800 μm; in step 4, the scanning speed of the scanning galvanometer 8 is 5000 mm / s, the repetition frequency is 5 kHz, and the energy density of the single-pulse laser 6 is 0.71-0.88 J / cm 2 The interval; in step 5, the transfer gap is 800 μm, in step 6, the ratio of the thickness of the thin-layer paste 2 to the transfer gap is 0.1, and it belongs to the third type of film thickness gap ratio ≥ 0.1; as Figure 9 The schematic diagram of the single-point transfer morphology for regulation is shown in FIG. 6, and the transfer threshold is 0.71 J / cm 2 . 4 4 2 4 4 3 .

[0056] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.​​​​​

Claims

1. A laser-induced thin-layer slurry large-gap transfer morphology control method, characterized in that: The steps include: Step 1: Prepare a uniform thin layer of slurry on a transparent donor substrate; the thin layer of slurry is a non-Newtonian fluid with shear-thinning rheological properties, a viscosity of 20-50 Pa·s, and a particle size of ≤3 μm, ensuring that the minimum thickness of the thin layer of slurry is greater than or equal to 5 times the particle size of the thin layer of slurry; Step 2: Place the transparent donor substrate coated with a thin layer of slurry and the receiving substrate to be printed on a high-precision displacement platform so that the position of the receiving substrate is fixed; and position the thin layer of slurry toward the receiving substrate and directly above the receiving substrate; The distance between the bottom of the thin layer of slurry and the receiving substrate is the transfer gap l , adjust the transfer gap l， Make it greater than or equal to 500 μm; Step 3: The pulse laser emits light to obtain a single pulse laser, which is focused on the interface between the transparent donor substrate and the thin layer slurry through a beam shaping module, a scanning galvanometer, and a telecentric field mirror; Step 4: Using a scanning galvanometer, a single pulse laser is transmitted through the transparent donor substrate to achieve induced point trajectory processing at different positions of the thin layer of slurry; Step 5: Single pulse laser induces bulges on the bottom of the thin layer of slurry through foaming, with a transfer gap greater than or equal to 500 μm. l Under the slurry, the thin layer is transferred in the form of a jet and deposited on the receiving substrate to form a single point array directly; Step 6: By adjusting the ratio of the thickness of the thin layer slurry and the transfer gap, that is, the film thickness gap ratio, the transfer gap is greater than or equal to 500μm. l Directly control and shape single-point arrays with different diameters, surface areas, heights, volumes, and cross-sectional morphologies. Step 7: Dry the printed single-dot array, observe the morphology of the formed dots using a laser scanning confocal microscope or a scanning electron microscope, and measure the diameter, surface area, height, volume, and cross-sectional morphology of the formed dots.

2. The method for controlling the morphology of a laser-induced thin-layer slurry large-gap transfer according to claim 1, characterized in that: The thin layer slurry is conductive silver slurry.

3. The method for controlling the morphology of laser-induced thin-layer slurry large-gap transfer according to claim 1, characterized in that: The step 4 includes setting processing parameters of the pulse laser and the scanning galvanometer to correspond to the transfer of thin layers of slurry of different thicknesses.

4. The method for controlling the morphology of laser-induced thin-layer slurry large-gap transfer according to claim 3, characterized in that: The energy density of single pulse laser is controlled at 0.27~0.88J / cm 2 , repetition frequency is greater than or equal to 300kHz; the speed of the scanning galvanometer is greater than or equal to 3000mm / s, and the repetition frequency is greater than or equal to 3kHz.

5. The method for controlling the morphology of laser-induced thin-layer slurry large-gap transfer according to claim 1, characterized in that: The distance between two adjacent points in the transferred single-point array is 1 mm.

6. The method for controlling the morphology of laser-induced thin-layer slurry large-gap transfer according to claim 1, characterized in that: In step 6, the control of the film thickness-gap ratio includes three categories: the first category has a film thickness-gap ratio of ≤0.03; the second category has a film thickness-gap ratio of 0.03-0.1; and the third category has a film thickness-gap ratio of ≥0.1.

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