Firstly, this paper presents an orthogonal test of six factors and five levels, called the chemical mechanical polishing （CMP） process parameters experiment, for determining the best process parameters and ranking t...Firstly, this paper presents an orthogonal test of six factors and five levels, called the chemical mechanical polishing （CMP） process parameters experiment, for determining the best process parameters and ranking the influencing factors from primary to secondary. The three most important factors are the polishing pressure, the polishing liquid concentration and the relative velocity ratio of polishing disk to polishing carrier. Then, based on this analysis, the three factors and three levels of the quadratic orthogonal regression test are put forward. A math- ematical model impacting the surface roughness has also been set up. Finally, this work has achieved a polished wafer, whose material removal rate （MRR） is in the range of 70-90 nm/h and the surface roughness （Ra） is between 0.3 nm and 0.5 nm.展开更多
Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphen...Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity.Meanwhile,graphene wrinkles,including folds and ripples,form during cooling due to the thermal contraction mismatch between graphene and the metal substrates,and have been far from suppressed or eliminated,especially in bilayer graphene,which would greatly degrade the extraordinary properties of graphene.Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition.Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire,the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s.The tensile-strained CuNi(111)film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling,which is directly observed through in situ optical microscopy.The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones.Our results offer a promising route for largescale production of bilayer graphene and enable its various applications.展开更多
基金Project supported by the National Natural Science Foundation of China(No.51375266)
文摘Firstly, this paper presents an orthogonal test of six factors and five levels, called the chemical mechanical polishing （CMP） process parameters experiment, for determining the best process parameters and ranking the influencing factors from primary to secondary. The three most important factors are the polishing pressure, the polishing liquid concentration and the relative velocity ratio of polishing disk to polishing carrier. Then, based on this analysis, the three factors and three levels of the quadratic orthogonal regression test are put forward. A math- ematical model impacting the surface roughness has also been set up. Finally, this work has achieved a polished wafer, whose material removal rate （MRR） is in the range of 70-90 nm/h and the surface roughness （Ra） is between 0.3 nm and 0.5 nm.
基金This work was supported by the National Natural Science Foundation of China(Nos.52021006,T2188101,and 22105009)Beijing National Laboratory for Molecular Sciences(No.BNLMSCXTD-202001)+1 种基金the Tencent Foundation(No.XPLORER PRIZE)We acknowledge Molecular Materials and Nanofabrication Laboratory(MMNL)in the College of Chemistry at Peking University for the use of instruments.
文摘Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity.Meanwhile,graphene wrinkles,including folds and ripples,form during cooling due to the thermal contraction mismatch between graphene and the metal substrates,and have been far from suppressed or eliminated,especially in bilayer graphene,which would greatly degrade the extraordinary properties of graphene.Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition.Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire,the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s.The tensile-strained CuNi(111)film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling,which is directly observed through in situ optical microscopy.The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones.Our results offer a promising route for largescale production of bilayer graphene and enable its various applications.
