The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasm...The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasma string induced by sub-pulses of the burst-mode is revealed according to the analysis of the instantaneous photoluminescence images. Due to the presence of residual plasma, the energy loss of sub-pulse during the balancing of self-focusing effect is reduced, and thus refreshes the plasma via refocusing. The refreshed plasma peak generated by the subsequent subpulse appears at relatively low density positions in the formed filamentary plasma string, which results in more uniform densities and less spatial overlap among the plasma peaks. The continuity and uniformity of the filamentary trace in sapphire are enhanced by the burst-mode. Besides, the burst filamentary propagation can also remain effective when the sub-pulse energy is below the self-focusing threshold. Based on this uniform and precise energy propagation mode, the feasibility of its use for the laser lift-off(LLO) process is verified.展开更多
It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in i...It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in industrial production. This paper experimentally investigated the mechanism and technologic characteristics of laser lift-off(LLO) process of ultra-thin(～ 2 μm) polyimide(PI)film. It was found increasingly difficult to obtain desirable ultra-thin PI film by LLO with the decrease of the film thickness. The optimal process parameters were achieved considering laser fluence and accumulated irradiation times(AIT), which were found to be strongly correlative to the thickness of PI film. The process mechanism of LLO of PI film was disclosed that laser ablation of interfacial PI will result in the formation of gas products between the PI and glass substrate, enabling the change of interface microstructures to reduce the interface bond strength. The amount of gas products mainly determines the result of LLO process for ultra-thin PI film, from residual adhesion to wrinkles or cracking. The strategy of multi-scanning based on multiple irradiations of low-energy laser pulses was presented to effectively achieve a reliable LLO process of ultra-thin PI film. This study provides an attractive route to optimize the LLO process for large-scale production of ultra-thin flexible electronics.展开更多
With the advent of human-friendly intelligent life,as well as increasing demands for natural and seamless humanmachine interactions,flexibility and wearability are among the inevitable development trends for electroni...With the advent of human-friendly intelligent life,as well as increasing demands for natural and seamless humanmachine interactions,flexibility and wearability are among the inevitable development trends for electronic devices in the future.Due to the advantages of rich physicochemical properties,flexible and stretchable inorganic oxide thin-film electronics play an increasingly important role in the emerging and exciting flexible electronic field,and they will act as a critical player in nextgeneration electronics.However,a stable strategy to render flexibility while maintaining excellent performance of oxide thin films is the most demanding and challenging problem,both for academic and industrial communities.Thus,this review focuses on the latest advanced strategies to achieve flexible inorganic oxide thin-film electronics.This review emphasizes the physical transferring strategies that are based on mechanical peeling and the chemical transferring strategies that are based on sacrificial layer etching.Finally,this review evaluates and summarizes the merits and demerits of these strategies toward actual applications,concluding with a future perspective into the challenges and opportunities for the next-generation of flexible inorganic oxide thin-film electronics.展开更多
A process methodology has been adopted to transfer GaN thin films grown on sapphire substrates to Si substrates using metal bonding and laser lift-off techniques. After bonding, a single KrF （248 nm） excimer laser p...A process methodology has been adopted to transfer GaN thin films grown on sapphire substrates to Si substrates using metal bonding and laser lift-off techniques. After bonding, a single KrF （248 nm） excimer laser pulse was directed through the transparent sapphire substrates followed by low-temperature heat treatment to remove the substrates. The influence of bonding temperature and energy density of the excimer laser on the structure and optical properties of GaN films were investigated systemically. Atomic force microscopy, X-ray diffraction and photoluminescence measurements showed that （1） the quality of the GaN film was higher at a lower bonding temperature and lower energy density; （2） the threshold of the energy density of the excimer laser lift-off GaN was 300 mJ/cm^2. The root-mean-square roughness of the transferred GaN surface was about 50 nm at a bonding temperature of 400 ℃.展开更多
Deterministic assembly techniques that enable programmatic and massively parallel integration of chips are essential for the development of novel electronic systems such as micro LED displays.However,large-area integr...Deterministic assembly techniques that enable programmatic and massively parallel integration of chips are essential for the development of novel electronic systems such as micro LED displays.However,large-area integration of ultrathin micro-chips with high yield and transfer accuracy remains a great challenge due to the difficulties in selective transfer,adhesion switchability,and transfer deviation.Here,a“laser projection proximity transfer(Laser PPT)”technique is presented for the deterministic assembly of microchip arrays at scale.One of the remarkable features is that the transfer status between the chip and the receiver substrate evolves from the original non-contact mode to contact mode for high-precision transfer,which overcomes the strict requirements of the flatness of stamp and substrate in contact-style transfer,and flight deviation of microchip array in noncontact-style transfer.Another feature is the rapid modulation of interfacial adhesion for reliable transfer via the use of thermally expandable microspheres to form microstructures and combining with a laser-induced blister.The adhesion regulation range is over 20 times without any damage to chip arrays.The results show that the transfer accuracy has been improved substantially with a minimum relative error of~0.5%.Combined with a laser beam projection system,demonstrations of Laser PPT for selective assembly of fragile objects onto challenging non-adhesive/cured surfaces in batch illustrate its potential in the highprecision integration of microscale chips at scale.展开更多
基金Project(51975017) supported by the National Natural Science Foundation of ChinaProject(KZ202110005012) supported by the Scientific Research Project of Beijing Educational Committee+1 种基金ChinaProject(2018YFB1107500) supported by the National Key R&D Program of China。
文摘The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasma string induced by sub-pulses of the burst-mode is revealed according to the analysis of the instantaneous photoluminescence images. Due to the presence of residual plasma, the energy loss of sub-pulse during the balancing of self-focusing effect is reduced, and thus refreshes the plasma via refocusing. The refreshed plasma peak generated by the subsequent subpulse appears at relatively low density positions in the formed filamentary plasma string, which results in more uniform densities and less spatial overlap among the plasma peaks. The continuity and uniformity of the filamentary trace in sapphire are enhanced by the burst-mode. Besides, the burst filamentary propagation can also remain effective when the sub-pulse energy is below the self-focusing threshold. Based on this uniform and precise energy propagation mode, the feasibility of its use for the laser lift-off(LLO) process is verified.
基金the National Natural Science Foundation of China(Grant Nos.51635007&51705180)Hubei Province Technology Innovation Special Projects(2017AAA002)
文摘It is increasingly crucial for flexible electronics to efficiently and reliably peel large-area, ultra-thin flexible films off from rigid substrate serving as substrates of flexible electronics device, especially in industrial production. This paper experimentally investigated the mechanism and technologic characteristics of laser lift-off(LLO) process of ultra-thin(～ 2 μm) polyimide(PI)film. It was found increasingly difficult to obtain desirable ultra-thin PI film by LLO with the decrease of the film thickness. The optimal process parameters were achieved considering laser fluence and accumulated irradiation times(AIT), which were found to be strongly correlative to the thickness of PI film. The process mechanism of LLO of PI film was disclosed that laser ablation of interfacial PI will result in the formation of gas products between the PI and glass substrate, enabling the change of interface microstructures to reduce the interface bond strength. The amount of gas products mainly determines the result of LLO process for ultra-thin PI film, from residual adhesion to wrinkles or cracking. The strategy of multi-scanning based on multiple irradiations of low-energy laser pulses was presented to effectively achieve a reliable LLO process of ultra-thin PI film. This study provides an attractive route to optimize the LLO process for large-scale production of ultra-thin flexible electronics.
基金the National Basic Research Program of China(973 Program)under Grant No.2015CB351905the Technology Innovative Research Team of Sichuan Province of China(No.2015TD0005)"111"project(No.B13042),China National Funds for Distinguished Young Scientists(No.61825102).
文摘With the advent of human-friendly intelligent life,as well as increasing demands for natural and seamless humanmachine interactions,flexibility and wearability are among the inevitable development trends for electronic devices in the future.Due to the advantages of rich physicochemical properties,flexible and stretchable inorganic oxide thin-film electronics play an increasingly important role in the emerging and exciting flexible electronic field,and they will act as a critical player in nextgeneration electronics.However,a stable strategy to render flexibility while maintaining excellent performance of oxide thin films is the most demanding and challenging problem,both for academic and industrial communities.Thus,this review focuses on the latest advanced strategies to achieve flexible inorganic oxide thin-film electronics.This review emphasizes the physical transferring strategies that are based on mechanical peeling and the chemical transferring strategies that are based on sacrificial layer etching.Finally,this review evaluates and summarizes the merits and demerits of these strategies toward actual applications,concluding with a future perspective into the challenges and opportunities for the next-generation of flexible inorganic oxide thin-film electronics.
基金supported by the National Natural Science Foundation of China(Nos.50672079,60676027,60837001,60776007)the State Key Development Program for Basic Research of China(No.2007CB613404)+1 种基金the Natural Science Foundation of Fujian Province (No.2008J 0221)the Science and Technology Program of the Educational Office of Fujian Province(No.JB08215)
文摘A process methodology has been adopted to transfer GaN thin films grown on sapphire substrates to Si substrates using metal bonding and laser lift-off techniques. After bonding, a single KrF （248 nm） excimer laser pulse was directed through the transparent sapphire substrates followed by low-temperature heat treatment to remove the substrates. The influence of bonding temperature and energy density of the excimer laser on the structure and optical properties of GaN films were investigated systemically. Atomic force microscopy, X-ray diffraction and photoluminescence measurements showed that （1） the quality of the GaN film was higher at a lower bonding temperature and lower energy density; （2） the threshold of the energy density of the excimer laser lift-off GaN was 300 mJ/cm^2. The root-mean-square roughness of the transferred GaN surface was about 50 nm at a bonding temperature of 400 ℃.
基金supported by the National Natural Science Foundation of China(Grant Nos.51925503,52188102,and 52105576)the Natural Science Foundation of Hubei Province of China(Grant No.2020CFA028)。
文摘Deterministic assembly techniques that enable programmatic and massively parallel integration of chips are essential for the development of novel electronic systems such as micro LED displays.However,large-area integration of ultrathin micro-chips with high yield and transfer accuracy remains a great challenge due to the difficulties in selective transfer,adhesion switchability,and transfer deviation.Here,a“laser projection proximity transfer(Laser PPT)”technique is presented for the deterministic assembly of microchip arrays at scale.One of the remarkable features is that the transfer status between the chip and the receiver substrate evolves from the original non-contact mode to contact mode for high-precision transfer,which overcomes the strict requirements of the flatness of stamp and substrate in contact-style transfer,and flight deviation of microchip array in noncontact-style transfer.Another feature is the rapid modulation of interfacial adhesion for reliable transfer via the use of thermally expandable microspheres to form microstructures and combining with a laser-induced blister.The adhesion regulation range is over 20 times without any damage to chip arrays.The results show that the transfer accuracy has been improved substantially with a minimum relative error of~0.5%.Combined with a laser beam projection system,demonstrations of Laser PPT for selective assembly of fragile objects onto challenging non-adhesive/cured surfaces in batch illustrate its potential in the highprecision integration of microscale chips at scale.
基金supported by the National Key Research and Development Program of China(2017YFE0131500)the National Natural Science Foundation of China(62104204 and U21A20493)。
