A high-throughput laser transfer method for solid-state thin films

Abstract

The present invention discloses a high-throughput laser transfer method for solid-state thin films, comprising the following steps: A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid-state thin film, wherein the solid-state thin film is adhered to the inner surface of the transparent substrate; B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and inner surface of the transparent substrate and irradiate the solid-state thin film to form a melted area; C. after a preset time interval, applying a second transfer laser to the transfer film, allowing the second transfer laser to sequentially pass through the outer surface and inner surface of the transparent substrate and irradiate the melted area of ​​the solid-state thin film. The laser transfer method of this solution utilizes two transfer lasers with different peak power densities to irradiate the solid-state thin film within a preset time interval, causing the solid-state thin film to undergo changes mainly based on the preset effect, thereby achieving a high-throughput transfer process.

Description

Technical Field

[0001] The present invention relates to the technical field of laser transfer, and in particular to a high-throughput laser transfer method for a solid-state thin film. Background Art

[0002] Laser transfer technology is a manufacturing method based on the principle of laser-induced forward transfer. It uses pulsed laser irradiation on a thin film material attached to a transparent substrate to achieve local transfer of the thin film material, forming a point, two-dimensional or three-dimensional structure by point-by-point accumulation. The above-mentioned thin film material is also called a donor, and both liquid slurry thin layers and solid films can be used as donors. When using a solid film as a donor, the donor has higher consistency and is free of instability and contamination problems caused by the fluid. Therefore, it can not only achieve high-precision transfer, but also facilitate the storage of the donor and its wide application in various complex sites.

[0003] However, when using solid-state films as donors, the reported donor thickness is generally only on the nanometer or submicron scale. For example, the Chinese invention patent "Method and Apparatus for Repairing Printed Circuit Traces" with publication number CN104797087A discloses that the donor film thickness is related to the laser pulse width, and the donor film thickness is ≤1μm. This is because traditional laser transfer methods generally use a single short-pulse laser to irradiate the donor, resulting in a competition between the thermal diffusion and surface push effect after the laser action. Ordinary short-pulse lasers have a high peak power density and a strong surface push effect, making it difficult for the laser's thermal effect on the donor to be effectively diffused, resulting in film tearing. Therefore, traditional laser transfer methods must use a thin donor film.

[0004] Furthermore, the thin thickness of the solid donor film used in existing technologies increases the difficulty and cost of manufacturing, while also reducing the efficiency of the laser transfer process, limiting its application scenarios. Therefore, reducing the difficulty and cost of manufacturing solid donor films while achieving fast and stable material transfer is a major challenge facing this technology. Summary of the Invention

[0005] The purpose of the present invention is to propose a high-throughput laser transfer method for solid-state thin films, which is conducive to achieving high-throughput transfer of solid-state thin films, reducing the manufacturing difficulty and cost of solid-state donor films while achieving rapid and stable material transfer, so as to overcome the shortcomings of the existing technology.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A high-throughput laser transfer method for solid-state thin films comprises the following steps:

[0008] A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate;

[0009] B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area;

[0010] C. After a preset time interval, applying a second transfer laser to the transfer film, allowing the second transfer laser to sequentially pass through the outer surface and inner surface of the transparent substrate and irradiate the melted area of ​​the solid film;

[0011] In step B, the peak power density of the first transfer laser when it reaches the solid film is ≤50MW / cm 2 ;

[0012] In step C, the peak power density of the second transfer laser when it reaches the solid film is ≥100MW / cm 2 .

[0013] Preferably, in step C, the preset time interval is a, in units of s, and a satisfies:

[0014] 0.1*(b 2 / c)≤a≤10*(b 2 / c);

[0015] Wherein, b is the thickness of the solid film, in m; c is the thermal diffusivity of the material of the solid film, in m 2 / s.

[0016] Preferably, in step B, the first transfer laser is a continuous laser.

[0017] Preferably, in step B, the first transfer laser is a pulsed laser, and the pulse width of the first transfer laser is ≥1 μs.

[0018] Preferably, in step C, the second transfer laser is a pulsed laser, and the pulse width of the second transfer laser is 0.1 to 100 ns.

[0019] Preferably, the thickness of the solid film is ≥5 μm.

[0020] The technical solution provided by the present invention can have the following beneficial effects:

[0021] 1. This solution first irradiates the solid film with a first transfer laser of lower peak power density. This causes the solid film to primarily undergo a thermal diffusion effect after the laser exposure, melting the irradiated area of ​​the solid film and forming a melted region. Once the irradiated area of ​​the solid film has melted to a certain degree, i.e., after a preset time interval, a second transfer laser with higher peak power density is then irradiated on the melted region of the solid film. This concentrates the power input, causing the melted region of the solid film to primarily undergo a surface push effect after the laser exposure, pushing the partially or completely melted film material in the melted region to vaporize and transfer, achieving a stable and high-throughput transfer effect.

[0022] 2. Because this approach utilizes two transfer lasers with different peak power densities to illuminate the solid film at predetermined intervals, it achieves a high-throughput transfer process for solid films. Therefore, even when applying this high-energy laser transfer method to thick solid films, it ensures stable transfer and guaranteed transfer quality. Furthermore, the effective use of thick solid films reduces the manufacturing difficulty and cost associated with using thinner solid donor films in existing technologies, significantly addressing the shortcomings of existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flow chart of a high-throughput laser transfer method for a solid-state thin film according to the present invention.

[0024] Figure 2 Schematic diagram of the solid-liquid region evolution of the solid film in Example 1 of the present invention.

[0025] Figure 3 Schematic diagram of the evolution of the maximum temperature in the solid film over time in Example 1 of the present invention.

[0026] Figure 4 Schematic diagram of the evolution of the maximum temperature in the solid film over time in Example 2 of the present invention.

[0027] Figure 5 Schematic diagram of the solid-liquid region evolution of the solid film in Example 3 of the present invention.

[0028] Figure 6 Schematic diagram of the evolution of the maximum temperature in the solid film over time in Example 3 of the present invention. DETAILED DESCRIPTION

[0029] A high-throughput laser transfer method for solid-state thin films comprises the following steps:

[0030] A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate;

[0031] B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area;

[0032] C. After a preset time interval, applying a second transfer laser to the transfer film, allowing the second transfer laser to sequentially pass through the outer surface and inner surface of the transparent substrate and irradiate the melted area of ​​the solid film;

[0033] In step B, the peak power density of the first transfer laser when it reaches the solid film is ≤50MW / cm 2 ;

[0034] In step C, the peak power density of the second transfer laser when it reaches the solid film is ≥100MW / cm 2 .

[0035] Since traditional laser transfer methods generally use a single short-pulse laser to irradiate the donor, the thermal diffusion and surface pushing effect after the laser action compete with each other. Ordinary short-pulse lasers have a high peak power density and a strong surface pushing effect, making it difficult for the laser's thermal effect on the donor to be effectively diffused, and the film will tear.

[0036] Therefore, in order to effectively utilize the thermal diffusion and surface pushing effects after the laser acts on the solid film, the laser transfer method of this scheme uses two transfer lasers with different peak power densities to irradiate the solid film separately within a preset time interval, so that the solid film undergoes changes mainly based on the preset effect, thereby realizing a high-throughput transfer process.

[0037] Specifically, this solution first irradiates the solid film with a first transfer laser having a low peak power density, causing the solid film to primarily undergo a thermal diffusion effect after the laser exposure (at this point, the surface push effect is weak), thereby melting the irradiated area of ​​the solid film and forming a melted region. Once the irradiated area of ​​the solid film has melted to a certain degree, i.e., after a predetermined time interval, a second transfer laser having a higher peak power density is then irradiated on the melted region of the solid film, concentrating the power input. This causes the melted region of the solid film to primarily undergo a surface push effect (at this point, the thermal diffusion effect is weak), driving the partially or completely melted film material in the melted region to vaporize and transfer, thereby achieving a stable and high-throughput transfer effect.

[0038] To further illustrate, in step C, the preset time interval is a, in seconds, and a satisfies:

[0039] 0.1*(b 2 / c)≤a≤10*(b 2 / c);

[0040] Wherein, b is the thickness of the solid film, in m; c is the thermal diffusivity of the material of the solid film, in m 2 / s.

[0041] In addition, to ensure both effective melting and stability of the melted area, this solution also optimizes the preset time interval a to satisfy the above formula, effectively ensuring that the irradiated area of ​​the solid film after the first transfer laser irradiation is in a melt-through state. If the preset time interval between the first transfer laser and the second transfer laser is too short, the melt depth of the solid film will be shallow, and even under the action of the second transfer laser, it will not be easy to stably separate from the inner surface of the transparent substrate. If the preset time interval between the first transfer laser and the second transfer laser is too long, the irradiated area of ​​the solid film will remain in a liquid state for a long time, which may cause the molten pool to be unstable and affect the transfer quality.

[0042] To further illustrate, in step B, the first transfer laser is a continuous laser.

[0043] In a preferred embodiment of this technical solution, the first transfer laser used in this solution is a continuous laser. Since the peak power density of the continuous laser is related to the average power of the laser and the laser spot size, the peak power density can be adjusted to meet the transfer requirements of this solution by adjusting these parameters.

[0044] To further illustrate, in step B, the first transfer laser is a pulsed laser, and the pulse width of the first transfer laser is ≥1 μs.

[0045] In another preferred embodiment of the present technical solution, the first transfer laser used in this solution is a pulsed laser with a pulse width ≥ 1μs. Among pulsed lasers with the same peak power density, the shorter the pulse width, the faster the heat input rate. Therefore, when the pulse width of the first transfer laser is too short, the temperature inside the solid film may rise sharply, exceeding the vaporization temperature in a short period of time, generating a strong surface driving force. Moreover, since the action time during the laser transfer process is generally short, it is easy to cause insufficient heat diffusion inside the solid film, making it difficult to ensure that after the first transfer laser irradiates the solid film, the solid film mainly undergoes a heat diffusion effect.

[0046] In addition, since the peak power density of the pulsed laser is also related to the single pulse energy of the laser and the laser spot size, the peak power density can be adjusted to meet the transfer requirements of this solution by adjusting the above parameters.

[0047] To further illustrate, in step C, the second transfer laser is a pulsed laser, and the pulse width of the second transfer laser is 0.1-100 ns.

[0048] Similarly, for pulsed lasers with the same peak power density, the shorter the pulse width, the faster the heat input rate. Since this solution requires that changes primarily due to the surface push effect occur after the second transfer laser irradiates the melted area of ​​the solid film, the pulse width of the second transfer laser is preferably set to 0.1 to 100 ns. If a laser with a longer pulse width is used at this time, the surface push effect will be less pronounced, making it difficult to transfer the melted area. If a laser with a shorter pulse width is used at this time, the surface push effect will be too pronounced, easily leading to fragmentation of the melted area.

[0049] Furthermore, the thickness of the solid film is ≥5 μm.

[0050] Because this approach utilizes two transfer lasers with different peak power densities to illuminate the solid film at predetermined intervals, it achieves a high-throughput transfer process for the solid film. Therefore, even when applying this high-energy laser transfer method to thick solid films, it ensures stable transfer and guaranteed transfer quality. Furthermore, the effective use of thick solid films reduces the manufacturing difficulty and cost associated with using thinner solid donor films in existing technologies, significantly addressing the shortcomings of existing technologies.

[0051] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0052] Example 1

[0053] A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate;

[0054] B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area;

[0055] C. After a preset time interval, a second transfer laser is applied to the transfer film, so that the second transfer laser sequentially passes through the outer surface and the inner surface of the transparent substrate and irradiates the melted area of ​​the solid film.

[0056] In step A, the transparent substrate is 1 mm thick fused quartz glass, and a metal copper film with a thickness of 10 μm is prepared on the inner surface of the transparent substrate by a magnetron sputtering composite electroplating method.

[0057] In step B, the first transfer laser uses a continuous laser with an average power of 80W and a wavelength of 532nm. After focusing, the spot size of the first transfer laser when it reaches the solid film is 25μm, and the peak power density is 16.3MW / cm 2 .

[0058] In step C, since the thermal diffusivity of copper is 1.17 cm 2 / s, so for a copper film with a thickness of 10μm, b 2 / c=855ns, so the preset time interval a in this embodiment is 4600ns. In addition, the second transfer laser uses a nanosecond pulse laser with a wavelength of 532nm, a single pulse energy of 1μJ, and a pulse width of 1.2ns. After focusing, the spot size of the second transfer laser reaching the melting area of ​​the solid film is 25μm, and the peak power density is 340MW / cm 2 .

[0059] When the first transfer laser is irradiated on the copper film, the solid-liquid region of the copper film evolves as follows: Figure 2 As shown in the figure, after the copper film is irradiated by the first transfer laser, the material in the laser action area begins to melt. With the continuous input of laser energy, the melting area continues to expand in the vertical direction, and the molten pool continues to deepen. At 4600ns, the molten pool depth reaches 10μm, at which point the copper film is completely melted through.

[0060] The maximum temperature evolution of the copper film over time from the start of the first transfer laser to the end of the second transfer laser is shown in the figure. Figure 3 As shown. During the first transfer laser action, due to its low peak power, the maximum temperature in the metal copper film is always lower than the vaporization temperature of metal copper (2840K). At this time, the physical phenomenon occurring inside the metal copper film is mainly due to the thermal diffusion effect, and there is no surface driving effect dominated by vaporization force. When the time reaches 4600ns, the second transfer laser begins to act. Due to its extremely high peak power, the maximum temperature in the metal copper film quickly exceeds the vaporization temperature of metal copper. At this time, the upper surface of the molten pool undergoes violent vaporization, generating a strong driving effect, squeezing the melted area of ​​the film downward. Given the good match between the penetration depth and the vaporization time at this time, the film has a stable instantaneous vaporization driving force when it is fully melted, and ultimately a stable and high-throughput transfer effect can be formed.

[0061] Example 2

[0062] A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate;

[0063] B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area;

[0064] C. After a preset time interval, a second transfer laser is applied to the transfer film, so that the second transfer laser sequentially passes through the outer surface and the inner surface of the transparent substrate and irradiates the melted area of ​​the solid film.

[0065] In step A, the transparent substrate is 1 mm thick fused quartz glass, and a metal copper film with a thickness of 5 μm is prepared on the inner surface of the transparent substrate by electron beam evaporation process.

[0066] In step B, the first transfer laser uses a pulse laser with a pulse width of 1 μs and a wavelength of 532 nm. After focusing, the spot size of the first transfer laser when it reaches the solid film is 25 μm, the single pulse energy is 65 μJ, and the peak power density is 26.5 MW / cm 2 .

[0067] In step C, since the thermal diffusivity of copper is 1.17 cm 2 / s, so for a copper film with a thickness of 5μm, b 2 / c=214ns, so the preset time interval a in this embodiment is 2000ns. In addition, the second transfer laser uses a nanosecond pulse laser with a wavelength of 355nm, a single pulse energy of 2μJ, and a pulse width of 1.5ns. After focusing, the spot size of the second transfer laser reaching the melting area of ​​the solid film is 25μm, and the peak power density is 543MW / cm 2 .

[0068] After the metal copper film is irradiated by the first transfer laser, the material in the laser action area begins to melt. With the continuous input of laser energy, the melting area continues to expand in the vertical direction, and the molten pool continues to deepen. At 2000ns, the metal copper film is completely melted through.

[0069] The maximum temperature evolution of the copper film over time from the start of the first transfer laser to the end of the second transfer laser is shown in the figure. Figure 4 As shown. During the first transfer laser action, due to its low peak power, the maximum temperature inside the metal copper film is always lower than the vaporization temperature of metal copper (2840K). At this time, the physical phenomenon occurring inside the metal copper film is mainly due to the thermal diffusion effect, and there is no surface driving effect dominated by vaporization force. When the time reaches 2000ns, the second transfer laser begins to act. Due to its extremely high peak power, the maximum temperature inside the metal copper film quickly exceeds the vaporization temperature of metal copper. At this time, the upper surface of the molten pool undergoes violent vaporization, generating a strong driving effect, squeezing the melted area of ​​the film downward. Given the good match between the penetration depth and the vaporization time at this time, the film has a stable instantaneous vaporization driving force when it is fully melted, and ultimately a stable and high-throughput transfer effect can be formed.

[0070] Example 3

[0071] A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate;

[0072] B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area;

[0073] C. After a preset time interval, a second transfer laser is applied to the transfer film, so that the second transfer laser sequentially passes through the outer surface and the inner surface of the transparent substrate and irradiates the melted area of ​​the solid film.

[0074] In step A, the transparent substrate is 1 mm thick fused quartz glass, and a metal tin film with a thickness of 5 μm is prepared on the inner surface of the transparent substrate by a magnetron sputtering process.

[0075] In step B, the first transfer laser uses a continuous laser with an average power of 30W and a wavelength of 532nm. After focusing, the spot size of the first transfer laser when it reaches the solid film is 25μm, and the peak power density is 6.1MW / cm 2 .

[0076] In step C, since the thermal diffusivity of tin is 0.40 cm 2 / s, so for a tin film with a thickness of 5μm, b 2 / c=625ns, so the preset time interval a in this embodiment is 180ns. In addition, the second transfer laser uses a nanosecond pulse laser with a wavelength of 532nm, a single pulse energy of 0.5μJ, and a pulse width of 1.5ns. After focusing, the spot size of the second transfer laser reaching the melting area of ​​the solid film is 25μm, and the peak power density is 136MW / cm 2 .

[0077] When the first transfer laser irradiates the metal tin film, the solid-liquid region of the metal tin film evolves as follows Figure 5 As shown in the figure, after the metal tin film is irradiated by the first transfer laser, the material in the laser action area begins to melt. With the continuous input of laser energy, the melting area continues to expand in the vertical direction, and the molten pool continues to deepen. At 180ns, the molten pool depth reaches 4μm, at which point the metal tin film is mostly melted through.

[0078] The maximum temperature of the metal tin film evolves with time from the start of the first transfer laser to the end of the second transfer laser. Figure 6As shown. During the first transfer laser action, due to its low peak power, the maximum temperature in the metal tin film is always lower than the vaporization temperature of metal tin (2875K). At this time, the physical phenomenon occurring inside the metal tin film is mainly due to the thermal diffusion effect, and there is no surface driving effect dominated by vaporization force. When the time reaches 180ns, the second transfer laser begins to act. Due to its extremely high peak power, the maximum temperature in the metal tin film quickly exceeds the vaporization temperature of metal tin. At this time, the upper surface of the molten pool undergoes violent vaporization, generating a strong driving effect, squeezing the melted area of ​​the film downward. Given the good match between the penetration depth and the vaporization time at this time, the film has a stable instantaneous vaporization driving force when it is fully melted, and ultimately a stable and high-throughput transfer effect can be formed.

[0079] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A high-throughput laser transfer method for solid-state thin films, characterized in that: The following steps are involved: A. preparing a transfer film, wherein the transfer film comprises a transparent substrate and a solid film, wherein the solid film is attached to the inner surface of the transparent substrate; B. applying a first transfer laser to the transfer film, allowing the first transfer laser to sequentially pass through the outer surface and the inner surface of the transparent substrate and irradiate the solid film to form a melted area; C. After a preset time interval, applying a second transfer laser to the transfer film, allowing the second transfer laser to sequentially pass through the outer surface and inner surface of the transparent substrate and irradiate the melted area of ​​the solid film; In step B, the peak power density of the first transfer laser when it reaches the solid film is ≤50 MW / cm 2 ; In step C, the peak power density of the second transfer laser when it reaches the solid film is ≥100 MW / cm 2 , the preset time interval is a, the unit is s, and a satisfies: 0.1*(b2 / c)≤a≤10*(b2 / c); Wherein, b is the thickness of the solid film, in m; c is the thermal diffusivity of the material of the solid film, in m 2 / s.

2. The high-throughput laser transfer method for solid-state thin films according to claim 1, characterized in that: In step B, the first transfer laser is a continuous laser.

3. The high-throughput laser transfer method for solid-state thin films according to claim 1, characterized in that: In step B, the first transfer laser is a pulse laser, and the pulse width of the first transfer laser is ≥1 μs.

4. The high-throughput laser transfer method for solid-state thin films according to claim 1, characterized in that: In step C, the second transfer laser is a pulse laser, and the pulse width of the second transfer laser is 0.1-100 ns.

5. The high-throughput laser transfer method for solid-state thin films according to claim 1, characterized in that: The thickness of the solid film is ≥5 μm.

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