【作者】 安涛；

【导师】 高勇；

【作者基本信息】 西安理工大学 ， 微电子学与固体电子学， 2014， 博士

【摘要】 随着半导体材料技术和半导体加工工艺日益成熟以及现代化电子行业迅猛发展需要,对现代半导体制造最基础的硅材料提出了大直径、高纯度、高完整性和高均匀性要求,即“三高一大。在晶体生长过程中,向坩埚内引入磁场是目前抑制对流提高晶体质量的重要方法。本文针对该方法的关键设备磁场目前存在的主要问题,以及大直径磁场及其对晶体生长的影响进行了相关研究。其主要内容如下:(1)通过对直拉法晶体生长坩埚内熔体温度分布、熔体对流以及磁场对熔体对流的抑制机理进行了分析研究,得到了坩埚内熔体主要存在四种对流,其中,热对流是主体对流,强度最强,作用区域最大,主要集中在熔体上部靠近坩埚壁区域;通过对勾形磁场抑制熔体对流机理研究,得到了勾形磁场的中心面坩埚壁处的径向分量Brmax、底部壁处的纵向分量Bzmax以及中心面下(上)20mm坩埚壁处的纵向分量Bzmin是磁场抑制熔体对流的关键参数。(2)依据相关理论分析推导出了勾形磁场的磁场强度(正交磁场)与等效微重力加速度之间的理论关系式:geff=(ρ·γ0·g0)/(μ2·σ·Δh2·B2),并对低卫星轨道的微重力环境下勾形磁场的关键参数进行了分析计算,得到了能有效抑制熔体主体对流的勾形磁场设计指标:Brmax为400GS、Bzmax为800GS、Bzmim小于110GS。为勾形磁场关键参数的确定在理论上提供了一种方法。(3)利用ANSYS有限元模拟软件对MCZ-6000A型单晶炉横向磁场和勾形磁场结构以及电学参数进行了优化设计,得到了磁场的优化设计参数。通过实验对其主要参数进行了验证。其结果表明了该模拟方法是正确的、符合实际的、完全可以信赖。为进一步磁场设计提供了一套完整的模拟方法以及具有参考价值的经验参数。(4)提出了一种具有上下导磁环和中心导磁环的勾形磁场新屏蔽体结构。该结构可减小磁回路磁阻,提高线圈的磁效率,降低磁场功耗。在其它条件相同条件下(线圈电流350A),使勾形磁场Brmax的强度提高了 27.0%;在相同Brmax强度(491GS)时,功耗降低了 36%。为降低勾形磁场功耗提供了一种新屏蔽体结构。(5)提出了一种高电压、小电流、低功耗的电压型勾形磁场结构。该磁场分布与现有勾形磁场的分布以及磁场特性规律完全相同。该磁场(2400 匝)与现有的勾形磁场(120匝)相比,在相同磁场Brmax强度(491.6GS)时,磁场功耗从原来的19.5KW降到9.8KW,降低了 50%。为研究开发、设计低功耗勾形磁场,提供了一种新的磁场结构。(6)通过晶体生长实验对设计的磁场进行了验证,结果表明了推导的磁场强度与等效微重力加速度之间理论关系式是正确的、符合实际的、完全可用于勾形磁场关键参数的计算。更多还原

【Abstract】 With the increasing maturity of semiconductor materials technology and semiconductor processing technology,and the need of the rapid development of modern electronic industry,we proposed the demand of "three high and one large" for the most basic of modern semiconductor manufacturing silicon materials,that is,high purity,high integrity and high uniformity.In the crystal growth process,the introduction of a magnetic field into the crucible is an important method to improve the crystal quality by suppressing the convection current.In this dissertation,for the main problem of the critical equipment of magnetic field in this method currently,we carry out a large-diameter magnetic field and do the research of its effects on crystal growth.The main contents are as follows:(1)We analyzed and researched temperature distribution in the melt crucible,melt convection and magnetic inhibition mechanism of melt convection starting from the basic principle of czochralski method of crystal growth.We found that there were four main convection of the crucible melt,and thermal convection was the main one which was the strongest,the role of the region’s largest and mainly influenced near the upper part of the crucible wall melt region;cusp magnetic field center plane of the crucible wall radial component Brmax,a bottom wall and a central longitudinal component of the surface under Bzmax 20mm,the crucible wall of the longitudinal component of the magnetic field Bzmin were the key parameters.(2)Based on relevant theory we derive the theoretical relationship between cusp magnetic field strength(orthogonal magnetic field)and the equivalent micro-gravity acceleration,geff=(ρ·γ0·g0)/(μ2·σ·Δh2·B2),analytically calculated the key parameters of cusp magnetic field in equivalent low orbit satellite at microgravity environment,and got the design parameters effectively suppressing convection in the melt cusp magnetic field,Brmax for 400GS,Bzmax for 800GS and Bzmin less than 110GS.It provided a way to determine theoretically the key parameters for the cusp magnetic field.(3)Transverse and cusp magnetic field structure of MCZ-6000A-type monocrystalline furnaces and their electrical parameters were optimized to obtain the optimal design parameters of the magnetic field.Its main parameters were verified through experimental verification,and it’s results showed that simulation method was correct,realistic and trusting.Provided a complete set of simulation methods for further design and field experience with a reference value of the parameter.(4)Proposed a kind of new shield structure of cusp magnetic having upper and lower magnetic permeability ring and the center magnetic permeability ring.This configuration can reduce the reluctance of the magnetic circuit,improve the magnetic efficiency of the coil and reduce the power consumption of magnetic field.In the same conditions of the others(coil current of 350A),it made the hook-shaped magnetic field Brmax strength increased 27.0%;in the same Brmax intensity(491GS),power consumption was reduced by 36%.To reduce the power consumption of the cusp magnetic field,it provided a new shield structure.(5)We presented a high-voltage,low-current and low-power consumption voltage-cusp magnetic field structure.It’s magnetic distribution and properties of the law were identical with the existing cusp magnetic field.This magnetic field(2400 turns)as compared with the existing cusp magnetic field(120 turns),the strength at the same magnetic field Brmax(491.6GS),the magnetic field reduced from the original 19.5kw to 9.8kw,by 50%.It provided a new magnetic field structure for researching and designing consumption cusp magnetic field.(6)Through the crystal growth experiment to validate the parameters of the magnetic field,the results show that the theoretical relation between magnetic field strength and the equivalent micro-g is correct,realistic and fully availabal for the design the key parameters of magnetic field.It provids a theoretical basis and method for the design of key parameters of cusp magnetic field.更多还原