Laser-induced thin-layer slurry large-gap transfer morphology regulation and control method

Abstract

The invention discloses a laser-induced thin-layer slurry large-gap transfer morphology regulation and control method. The method comprises the following steps: coating uniform thin-layer slurry with different thicknesses on a donor substrate; enabling the thin-layer slurry to face the receiving substrate, and controlling the transfer gap, namely 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 laser beam with high energy density on the interface of the donor substrate and the thin-layer slurry; single-pulse laser induction point track processing is realized through a scanning galvanometer with high scanning speed and high repetition frequency; by adjusting the ratio (smaller than or equal to 0.3, 0.3-0.1 and larger than or equal to 0.1) of the thickness of the thin-layer slurry to the transfer gap, single-point arrays with different diameters, surface areas, heights, volumes and section shapes can be directly transferred and formed. According to the invention, under a large transfer gap, single-point arrays with different morphologies can be directly regulated and formed, so that the tolerance of the transfer gap and the transfer efficiency are greatly improved, and the test cost is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of laser application and microelectronic printing, and in particular relates to a method for controlling the morphology of large-gap transfer of a thin-layer slurry induced by laser. Background Art

[0002] As the modern microelectronics printing industry gradually develops towards miniaturization, thinness and high controllability, higher requirements are placed on printing resolution and morphology regulation. How to quickly and efficiently achieve the printing of micro-graphic patterns with different morphologies has become an important challenge currently faced.

[0003] Laser direct writing technology is widely used in the preparation of micro-patterns in the fields of microelectronic circuits. Laser induced forward transfer technology (LIFT), as a new direct writing technology, has technical advantages such as non-contact, mask-free, simple process, flexible and controllable. In the research on laser-induced micro-pattern transfer forming technology, Chinese patent ZL202211369655.7 provides a method for regulating the geometric morphology of laser metallized grid lines. By adjusting the gap size between the bottom of the conductive paste and the solar cell and the matching relationship between the laser beam energy density, shaped grid lines with different geometric morphologies are prepared. However, this method is only applicable to small transfer gap conditions (≤20μm). Based on the transfer mechanism of laser-induced foaming driving the thin layer of slurry to form a slurry bridge connection and stretching separation between the thin layer of slurry and the receiving substrate, the tolerance for the transfer gap is low. Chinese patent CN112382676B discloses a laser-induced printing method for solar cell grid lines based on a double groove structure of a silicon wafer, in which a microstructure is prefabricated on the receiving substrate in advance, thereby controlling the geometric morphology of the contact between the slurry and the receiving substrate. However, this method adds processing steps.

[0004] The above-mentioned laser-induced micropattern transfer mainly focuses on the following two aspects in terms of the control method of the formed morphology: First, under a small transfer gap, laser-induced foaming drives the slurry to contact the receiving substrate in the form of a slurry bridge, and the laser energy density is matched to achieve morphology control; second, by prefabricating a microstructure on the donor or receiving substrate, the slurry transfer or deposition is geometrically constrained. However, small-gap transfer has a strict tolerance for the control of the transfer gap, and the separation process of the slurry bridge and the receiving substrate increases the instability of the formed morphology control; on the other hand, the pre-treatment process of the prefabricated microstructure increases the process and cost, and reduces production efficiency. Therefore, it is urgent to seek a flexible control method for the formed morphology under a large transfer gap. Summary of the invention

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

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

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

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

[0009] 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; the thin layer of slurry is directed toward the receiving substrate and is located 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, and the transfer gap l is adjusted to be greater than or equal to 500 μm;

[0010] Step 3, the pulse laser emits light to obtain a single pulse laser, and the single pulse laser 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;

[0011] Step 4: Using a scanning galvanometer, a single pulse laser is transmitted through a transparent donor substrate to achieve induced point trajectory processing at different positions of the thin layer slurry;

[0012] Step 5: A single pulse laser induces a bulge at the bottom of the thin layer of slurry through a foaming effect. Under a transfer gap l greater than or equal to 500 μm, the thin layer of slurry is transferred in the form of a jet and deposited on the receiving substrate to form a single point array;

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

[0014] Step 7: Dry the printed single-dot array, observe the morphological characteristics of the formed dots by laser scanning confocal microscopy or scanning electron microscopy, and measure the diameter, surface area, height, volume and cross-sectional morphology of the formed dots.

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

[0016] Furthermore, the thin layer slurry is conductive silver paste.

[0017] Furthermore, 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.

[0018] Furthermore, the energy density of the single-pulse laser is controlled at 0.27~0.88J / cm 2 , the 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.

[0019] Furthermore, the distance between two adjacent points in the transferred single-point array is 1 mm.

[0020] Furthermore, 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.

[0021] Beneficial effects:

[0022] (1) The present invention utilizes laser-induced non-contact transfer forming. When the transfer gap is greater than or equal to 500 μm, the transfer forming of single-point arrays with different morphologies can be directly controlled, adapting to the development trend of microelectronic circuit printing towards miniaturization, thinness and high controllability.

[0023] (2) Under a small transfer gap, laser-induced foaming drives the slurry to contact the receiving substrate in the form of a slurry bridge, matching the laser energy density to achieve morphology control or prefabricating a microstructure on the donor or receiving substrate to constrain the slurry transfer or deposition geometry. The present invention uses the film thickness gap ratio to control the transfer to form a single-point array of different morphologies under a large transfer gap, thereby improving the transfer gap control tolerance and avoiding the influence of the separation process of the slurry bridge and the receiving substrate on the forming morphology control; simplifying the pre-treatment process, reducing production costs, and improving transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0026] Figure 3 It is a schematic diagram of a single-point array formed by transfer.

[0027] Figure 4 It is a schematic diagram of the diameter and surface area regulation of the three types of film thickness gap ratio transfer points; among them, a is a schematic diagram of the change of single-point diameter of the three types of film thickness gap ratio transfer forming with the energy density, and b is a schematic diagram of the change of single-point surface area of ​​the three types of film thickness gap ratio transfer forming with the energy density.

[0028] Figure 5 It is a schematic diagram of the height and volume control of the three types of film thickness gap ratio transfer points; among them, a is a schematic diagram of the change of single point height of the three types of film thickness gap ratio transfer forming with energy density, and b is a schematic diagram of the change of single point volume of the three types of film thickness gap ratio transfer forming with energy density.

[0029] Figure 6 It is a schematic diagram of the surface and cross-sectional morphology control of three types of film thickness gap comparison transfer points.

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

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

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

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

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figure 1 As shown, the laser-induced thin-layer slurry large-gap transfer morphology control method of the present invention comprises the following steps:

[0036] Step 1: Prepare a uniform thin layer of slurry 2 on a transparent donor substrate 1 using a horizontal scraper;

[0037] Preferably, the thickness of the thin layer slurry 2 is h=15~80μm;

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

[0039] Step 2: Place the transparent donor substrate 1 coated with a thin layer of slurry 2 and the receiving substrate 3 to be printed on a high-precision displacement platform, and rely on the vacuum suction cup in the high-precision displacement platform 4 to adsorb the receiving substrate 3 so that the position of the receiving substrate 3 is fixed; make the thin layer of slurry 2 face the receiving substrate 3 and be located directly above the receiving substrate 3; the distance between the bottom of the thin layer of slurry 2 and the receiving substrate 3 is the transfer gap l, and adjust the transfer gap l to be greater than or equal to 500 μm.

[0040] Step 3: The pulse laser 5 emits light to obtain a single pulse laser 6. The single pulse laser 6 is focused on the interface between the transparent donor substrate 1 and the thin layer slurry 2 through the beam shaping module 7, the scanning galvanometer 8 and the telecentric field mirror 9. The whole system is placed on a high-precision marble platform 10. Figure 2 shown.

[0041] Step 4: Using the scanning galvanometer 8 , the single pulse laser 6 is transmitted through the transparent donor substrate 1 , and the induced point trajectory processing is realized at different positions of the thin layer slurry 2 .

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

[0043] Step 5: The single pulse laser 6 induces a bulge at the bottom of the thin layer of slurry 2 through foaming, such as Figure 3 As shown, under a transfer gap l greater than or equal to 500 μm, the thin layer slurry 2 is transferred in the form of a jet, deposited and formed on the receiving substrate 3, and directly transferred to form a single point array 11. There is no need to separate the slurry bridge from the receiving substrate, which reduces the interference of this process on the forming morphology. Controlling the viscosity of the thin layer slurry 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 slurry 2 to the transfer gap, i.e., the film thickness gap ratio, under a transfer gap l greater than or equal to 500 μm, single-point arrays of 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 explorations, the control of the film thickness gap ratio mainly includes three categories: the first category is a film thickness gap ratio ≤ 0.03; the second category is a film thickness gap ratio of 0.03~0.1; and the third category is a film thickness gap ratio ≥ 0.1.

[0045] Step 7: Dry the printed transfer single point array, observe the morphological characteristics of the formed points through 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 points.

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

[0047] The diameter and surface area of ​​the transfer point can be adjusted, including: 0.27~0.88J / cm 2 At the energy density, the first type of film thickness-gap ratio is ≤0.03, the diameter of the formed point is 100~350μm, and the surface area is 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 130-200 μm, and the surface area is 1×10 4 ~3×104 μm 2 ; The third type of film thickness-gap ratio is ≥0.1, the diameter of the formed point is 80~130μm, and the surface area is 0.5×10 4 ~1.5×10 4 μm 2 ,like Figure 4 As shown, Figure 4 a is a schematic diagram showing the change of single point diameter with energy density for three types of film thickness gap ratio transfer forming. Figure 4 b is a schematic diagram of the change of single-point surface area with energy density for three types of film thickness-gap ratio transfer forming.

[0048] Adjust the height and volume of the transfer point, including: 0.27~0.88J / cm 2 At the energy density, the first type of film thickness-gap ratio is ≤0.03, the height of the formed point is 8~18μm, 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 formed point is regulated to be 15~30μm, and the volume is 5×10 4 ~1.2×10 5 μm 3 ; The third type of film thickness-gap ratio is ≥0.1, the height of the formed point is regulated to be 15~30μm, and the volume is 2×10 4 ~6×10 4 μm 3 ,like Figure 5 As shown, Figure 5 a is a schematic diagram showing the change of single point height with energy density for three types of film thickness gap ratio transfer forming. Figure 5 b is a schematic diagram of the change of single-point volume with energy density for three types of film thickness-gap ratio transfer forming.

[0049] The surface and cross-sectional morphology of the transfer point are regulated, including: applicable to three types of film thickness-gap ratios, when the laser energy density is equal to the critical transfer threshold, the morphology of the transfer point is dome-shaped; when the laser energy density is greater than the critical transfer threshold, the morphology of the transfer point is pointed, such as Figure 6 As shown in Figure 1, the corresponding film thickness-to-gap ratio of Class 1 is ≤0.03, and the transfer threshold is 0.31 J / cm 2 ; The second type of film thickness-to-gap ratio is 0.03~0.1, and the transfer threshold is 0.40J / cm 2 ; Type 3 film thickness-to-gap ratio ≥ 0.1, transfer threshold 0.62 J / cm 2 .

[0050] Embodiment 1:

[0051] The laser-induced thin-layer slurry large-gap transfer morphology control method of Example 1 includes: in step 1, the thin-layer slurry 2 is a conductive silver slurry with a viscosity of 30 Pa·s, a particle size of the thin-layer slurry of 1 μm, and a thickness of the thin-layer slurry h=15 μm; in step 2, the transfer gap between the bottom of the thin-layer slurry 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 ; The transfer gap in step 5 is 500 μm, and the ratio of the thickness of the thin layer slurry 2 to the transfer gap in step 6 is 0.03, which belongs to the first type of film thickness gap ratio ≤ 0.3; Figure 7 Schematic diagram of the single-point transfer morphology for controlled formation, with a transfer threshold of 0.31 J / cm 2 , with a diameter of 100~330μm and a surface area of ​​1×10 4 ~7×10 4 μm 2 , with a height of 8~17μm and a volume of 1.5×10 4 ~4×10 4 μm 3 .

[0052] Embodiment 2:

[0053] The laser-induced thin-layer slurry large-gap transfer morphology control method of Example 2 includes: in step 1, the thin-layer slurry 2 is a conductive silver slurry with a viscosity of 40 Pa·s, a particle size of the thin-layer slurry of 3 μm, and a thickness of the thin-layer slurry h=50 μm; in step 2, the transfer gap between the bottom of the thin-layer slurry 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 ; The transfer gap in step 5 is 1000 μm, and the ratio of the thickness of the thin layer slurry 2 to the transfer gap in step 6 is 0.05, which belongs to the second type of film thickness gap ratio of 0.03~0.1; Figure 8 Schematic diagram of the single-point transfer morphology for controlled formation, with a transfer threshold of 0.44 J / cm 2 , with a diameter of 132~197μm and a surface area of ​​1×10 4 ~2.9×10 4 μm 2 , with a height of 16~28μm and a volume of 5.5×10 4 ~1.1×10 5 μm 3 .

[0054] Embodiment 3:

[0055] The laser-induced thin-layer slurry large-gap transfer morphology control method of Example 3 includes: in step 1, the thin-layer slurry 2 is a conductive silver slurry with a viscosity of 50 Pa·s, a particle size of the thin-layer slurry of 2 μm, and a thickness of the thin-layer slurry h=80 μm; in step 2, the transfer gap between the bottom of the thin-layer slurry 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 interval; the transfer gap in step 5 is 800 μm, and the ratio of the thickness of the thin layer slurry 2 to the transfer gap in step 6 is 0.1, which belongs to the third type of film thickness gap ratio ≥ 0.1; Fig. 9 Schematic diagram of the single-point transfer morphology for controlled formation, with a transfer threshold of 0.71 J / cm 2 , with a diameter of 93~125μm and a surface area of ​​0.6×10 4 ~1.5×10 4 μm 2 , with a height of 18~28μm and a volume of 2.6×10 4 ~6×10 4 μm 3 .

[0056] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser-induced thin-layer slurry large gap transfer morphology control method, characterized in that: The steps include: Step 1: preparing a uniform thin layer of slurry on a transparent donor substrate; Step 2: placing 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; the thin layer of slurry faces the receiving substrate and is located 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, and the transfer gap l is adjusted to be greater than or equal to 500 μm; Step 3, the pulse laser emits light to obtain a single pulse laser, and the single pulse laser 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 a transparent donor substrate to achieve induced point trajectory processing at different positions of the thin layer slurry; Step 5: A single pulse laser induces a bulge at the bottom of the thin layer of slurry through a foaming effect. Under a transfer gap l greater than or equal to 500 μm, the thin layer of slurry is transferred in the form of a jet and deposited on the receiving substrate to form a single point array; Step 6: By adjusting the ratio of the thickness of the thin layer slurry and the transfer gap, i.e., the film thickness-gap ratio, a single-point array with different diameters, surface areas, heights, volumes, and cross-sectional morphologies can be directly controlled and formed at a transfer gap l greater than or equal to 500 μm; Step 7: Dry the printed single-dot array, observe the morphological characteristics of the formed dots by laser scanning confocal microscopy or scanning electron microscopy, 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: In step 1, the thin layer slurry is a non-Newtonian fluid with shear-thinning rheological properties, a viscosity of 20-50 Pa·s, and a particle size of the thin layer slurry ≤3 μm, ensuring that the minimum thin layer slurry thickness is greater than or equal to 5 times the particle size of the thin layer slurry.

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

4. 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 with different thicknesses.

5. The method for controlling the morphology of large gap transfer of thin layer slurry induced by laser according to claim 4, characterized in that: The energy density of single pulse laser is controlled at 0.27~0.88J / cm 2 , the 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.

6. 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 dots in the transfer-formed single-dot array is 1 mm.

7. 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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