Studies Of Copper Single Crystal Growth In Czochralski Technique And Preparation Of Copper Single Crystal Substrate

With select electrical conductivity, thermal conductivity, malleability andcorrosion resistance copper is widely used in electronic information, powertransmission, defense equipment, machinery manufacturing and other fields.Especially single-crystal copper shows a good prospect in the high-tech field of laserfusion targets. Meanwhile, with the face centered cubic structure, the close-packedsurface of single-crystal copper is narrow, and the coherence is large, for which thecopper single crystal can be used as the X-ray diffraction and neutron diffractionmonochromator. Comparing with polycrystalline copper, the mechanical andelectrical properties of copper single crystal are not affected by grain boundaries,which make copper single crystal a select substrate material. Copper single crystalsubstrates have important applications in thin films preparation, basic surfacesciences, microelectronics and other fields. For that the quality of substrate directlyaffects the performance of the film and electronic devices, preparation of high-qualitysingle crystal substrate will provide a reliable guarantee for the subsequent devices.Considering the main problems in the preparation of copper single crystal andsubstrate, this paper focus on the following aspects:1. The growth of copper single crystal is studied, and heat and mass transferprocess is also analyzed. The growth parameters are improved based on the analysisresult.Czochralski process parameters are as follow: pulling rate is0.01¹0mm/minwhile rotation rate is10³0r/min. The largest size of as-growth single crystal is Φ25×60mm³.2. Low pressure polishing process is designed to avoid damage of the coppersingle crystal surface. After polishing the surface Roughness Average is1.7nm.CMP slurry formulation is as follow:1⁵%by weight of SiO₂sol, H₂O₂,0.3¹%,10⁴0%ethanol,1⁵%glycerol, the rest of the slurry is deionized water.3. Copper single crystal etching process is studied, and the defects of copper single crystal are analyzed based on the etching results.Surface slow etching formula is as follows:3%solution of nitric acid in ethanolor5%dilute hydrochloric acid. Metallographic etching formula is as follows: A:nitrate50%vt, acetic acid28%vt, phosphoric acid22%vt; B: Hydrochloric acid10%vt, ferric chloride7%wt, ethanol50%vt, water50%vt. The formula fordislocation etching solutions is as follow: HNO₃，10%wtand mass ratio of H₂O: HCl:FeCl3: KBr is80:10:3:1.Dislocation density is obtained by etching results: before polishing the crystalsurface dislocation density is108¹09/cm², and after polishing is1010¹011/cm².4. The polycrystalline phenomenon of plastic deformed copper single crystalduring annealing is studied.The minimum pressure leading to polycrystalline phenomenon is5.46×10⁷Pa.The starting temperature of the polycrystalline transition between300℃and400℃.The stored energy caused by stress damage release completely after annealing at500℃for1h.The grain boundary and the “dark point” column moving behavior duringannealing are studied. The research conclusion is that: the motion of dislocationsduring annealing is one of the driving force for grain growth.