自停止腐蚀工艺的观察

自停止腐蚀工艺是在大规模集成电路工艺基础上发展起来的一项腐蚀工艺 ,它利用不同浓度的腐蚀剂对不同掺杂浓度的硅片腐蚀速度差异 ,达到制备一定形状的器件的目的 ,这项工艺在微机械器件的制作中 ,具有特殊的意义。本文即是利用不同浓度的ＫＯＨ溶液对硼掺杂浓度小于 1× 1 0 19ｃｍ- 3 时的 <1 0 0 >硅 ,腐蚀速率为常数 ,而硼掺杂浓度超过该浓度时 ,腐蚀速率迅速下降的特点 ,来制备薄膜的。其主要工艺参数如下 :<1 0 0 >面双面抛光Ｐ型硅片 ,正面氧化 1 μｍ ,光刻硼扩散窗口。预氧化 ,80ｎｍ后 ,浓硼预淀积 ,温度 1 1 0 0℃ ,通Ｎ2 40ｍ…     

含水汽气氛扩散的微晶玻璃片状源特性及其在CMOS中的应用

硼微晶玻璃扩散源使用方便,价格低廉,在半导体器件制造中已应用较长时间。但它在一般预淀积温度下,淀积在半导体表面的硼硅玻璃较薄,浓度不易提高。如果提高温度,则会引起源片翘曲,且在硅片表面形成一层有害的硼硅相。因此,这种源片很少在高密度的集成电路中应用。本工作着重研究了在预淀积中增加并控制一定量的水汽在整个饱和气 体中的含量,使源片表面HBO_2的蒸发速率明显提高(HBO_2饱和蒸气压比B_2O_3大得多),从而得到一层更均匀,浓度更高,且较厚的的硼硅玻璃层。通过实验,给出了在不同的水汽含量及温度下与硼硅玻璃厚度t_(ox),薄层电阻ρ_S的关系曲线,得到了t_(ox),p_s均匀性、重复性曲线和纵向杂质分布曲线,并与常规预淀积条件下的t_(ox),ρ_S均匀性,重复性曲线,和杂质分布曲线作了比较。最后指出:该工艺在短沟道CMOS技术中,制作浅结p~+漏、源有特殊好处。克服了离子注入工艺中的“沟道效应”,为制作短沟道CMOS电路提供了方便。     

Si1-x-y GexCy的淀积工艺和材料特性

研究了利用减压外延的方法制备Si1-x-yGexCy薄膜的特性及与工艺参数之间的关系,给出了改善表面粗糙度、减少有源区关键尺寸(CD)减少量的方法。在单晶硅、图形硅片α-Si和光片α-Si表面Si1-x-yGexCy上淀积的Si1-x-yGexCy薄膜的表面形貌不同,在单晶硅上成长的是单晶态的Si1-x-yGexCy,在除单晶硅之外的材料上成长的都是多晶态的Si1-x-yGexCy,多晶态Si1-x-yGexCy的淀积速率高于单晶态Si1-x-yGexCy的淀积速率。多晶态Si1-x-yGexCy的淀积速率高于单晶态Si1-x-yGexCy的淀积速率,造成了淀积工艺完成后有源区CD的减少。利用低温淀积工艺和控制浅沟槽隔离(STI)凹陷的深度,可以有效减少由于淀积Si1-x-yGexCy薄膜造成的有源区CD减少量。同时,研究了碳组分对硼扩散的抑制作用,碳组分越高,对硼扩散的抑制作用越大。     

硅中由离子注入和化学源预淀积的同时扩散期间砷和硼之间的互作用

砷和硼从预淀积层(化学源或离子注入)作同时扩散,已被用来分别制作微波晶体管的发射区和基区。这类晶体管掺杂分布的数学模拟表明:在预淀积——扩散结构中,砷-硼(化学源)的相继扩散中所发生的扩散互作用效应是不显著的。其结果是,由这样的工艺制造的晶体管没有基区迟滞现象,而且其有源基区掺杂浓度要比由以前确立的扩散方程所预计的高些。为了确定互作用效应重要到何种程度,测量了晶体管的掺杂分布,并与计算的分布作了比较。把电场的相互作用、[V_(si)As_2]络合物形成而引起的空位欠饱和的状况以及离子配偶都包括在内,估计出每一种作用对于硼扩散的重要性是可能的。业已表明,在预淀积——扩散结构中,其电场互作用要比在恒定表面浓度扩散(非耗尽源)中的小2到3倍。更重要的是,在从预淀积层同时扩散砷-硼期间,发生的空位欠饱和是可忽略的。在化学源砷预淀积的情况中,这是由于在预淀积期间(在与硼同时扩散之前)就达到了一个[V_(si)As_2]络合物的准平衡浓度。在离子注入预淀积砷的情况中,对于剂量≤3×10~(15)厘米~(-2)时,络合物好像是或者在注入期间形成的,或者在退火期间非常迅速地形成的。给出的数据表明,在砷注入——退火结构中,没有非电活性的砷络合物形成,在这个结构中,已接近As~ 离子的最大溶解度了(在1000℃下或剂量为5～8×10~(15)厘米~(-2)时为3.8×10~(20)厘米~(-3))。这个结果适合于本研究中所用的砷剂量。由于这个结果在由化学源作扩散的砷掺杂层中没有观察到,为了解释这个异常现象,尚需进一步作研究工作。     

氮化硼片源扩散下的硅表面机构

本文描述用红外透射光谱,椭偏光仪和四探针测量,对氮化硼片源扩散下的硅表面结构和质量输运所进行的观测和分析。实验发现,预扩后的硅表面是由未反应HBO-2淀积层—硼硅玻璃层—Si-B相层组成的。这种表面系统的形成和发展与扩散的具体条件(温度、时间、气氛、源到硅片的间距)有关。对表面过程的分析表明,这种表面结构是反应扩散的结果。表面新相的形成减缓了硼向硅中的扩散,保证了硅表面硼浓度处处是固溶度饱和的。     

锑化铟红外探测器二氧化硅钝化膜中氢含量的分析

用氦离子前角反冲技术研究了等离子体增强化学气相淀积工艺制备的红外探测器二氧化硅钝化膜膜层内的氢含量、浓度以及氢分布的深度。结果表明,所测量的氢分布深度与椭偏法所测得膜厚结果是一致的,膜层中氢的含量随淀积时间的增加是非线性的、氢含量与浓度随淀积温度和射频功率密度的增加而减少。实验也表明了膜层的腐蚀速率与氢含量的关系。     

一种低成本的硅垂直互连技术

采用KOH刻蚀工艺制作硅垂直互连用通孔,淀积SiO2作为硅垂直互连的电绝缘层,溅射Ti和Cu分别作为Cu互连线的黏附层/扩散阻挡层和电镀种子层.电镀10μm厚的Cu作为硅垂直互连的导电层.为实现金属布线的图形化,在已有垂直互连的硅片上试验了干膜光刻工艺.采用化学镀工艺,在Cu互连线上沉积150～200 nm厚的NiMoP薄膜作为防止Cu腐蚀和Cu向其上层介质扩散的覆盖层.高温退火验证了Ti阻挡层和NiMoP覆盖层的可靠性.     

样品键合:键合工艺的研究与检查

硅片直接键合是一种为传感器工艺提供广泛应用范围的新技术.它仅需基本的标准硅加工设备,它的基本工艺是把两个氧化的样片在室温下键合,然后高温退火,可得到隐埋氧化层.加上掺杂和薄的外延淀积可以得到多种腐蚀自停止层.结合各向异性及优向腐蚀技术,则使膜片生产、在硅氢化中冷却沟道的生产和微机械器件的生产等各种各样的应用更加灵活.     

基于Si3N4掩模的太阳电池选择性掺杂工艺研究

设计了基于Si3N4掩模的太阳电池选择性掺杂工艺,并对其工艺参数进行了仿真优化。选择性掺杂电池的一次掺杂条件为仿真所得最佳非选择性掺杂电池的工艺参数。运用SILVACO软件分别对选择性掺杂的时间、预淀积浓度和温度进行了仿真研究。仿真结果表明,随着选择性掺杂的预淀积浓度的增加,光谱响应率先增加后降低;随着扩散温度和扩散时间的增加,电池的光谱响应率逐渐减小。所得最佳选择性掺杂工艺参数为预淀积磷硅玻璃杂质浓度1×1019 cm-3、扩散温度800℃、扩散时间5min。     

三重扩散工艺的改进

用三重扩散工艺生产功率晶体管,已是国内较通用的工艺,它的主要工艺流程如图1。很显然,由于硅片两面进行深结磷扩散,本来只需要200微米厚的硅片,不得不加厚至400微米。同时,100小时的高温扩散,极易产生沾片,使硅片损耗很大。为此,我们对三重扩散工艺进行了改进,如图2。改进之处是,衬底磷预淀积以后,将硅片     

Modeling of junction formation and drive-in in ion implanted HgCdTe

N-on-p junction formation and drive-in in ion implanted Hg_0.8Cd_0.2Te photodiodes have been studied. A model of the junction formation and drive-in processes has been developed that accounts for the variations in injected Hg interstitial concentration, background point defect and extrinsic doping levels, sample geometry, and annealing conditions. The limiting mechanisms controlling junction drive-in were investigated using the model. Experimental data showed the junction drive-in rate was proportional to the square root of time, indicating a diffusion limited process. The diffusion limited process is the result of a solubility limit for the Hg interstitial concentration. This limit is approximately the same value as that obtained for Hg interstitials in Hg saturated Hg_0.8Cd_0.2Te in type conversion and self-diffusion experiments (D_IC_I = 1.43 × 10₁₃exp(−.457 eV/ kT)*P_Hg).     

新型片状磷平面扩散源的应用研究

分析了新型片状固态磷平面扩散源(PDS)的掺杂机理,并与液态POCl3源扩散进行了比较,指出可用片状固态磷PDS来替代POCl3实现磷扩散工艺的预沉积。基于PDS预沉积的实验结果,分析了影响方块电阻大小及其均匀性的关键因素,给出了工艺方案,并通过实际产品的电学参数测量结果验证了工艺方案的可行性,可供新型片状磷PDS在大直径硅扩散工艺中的推广使用参考。     

应用于MEMS封装的TSV工艺研究

开展了应用于微机电系统(MEMS)封装的硅通孔(TSV)工艺研究,分析了典型TSV的工艺,使用Bosch工艺干法刻蚀形成通孔,气体SF6和气体C4F8的流量分别为450和190 cm3/min,一个刻蚀周期内的刻蚀和保护时长分别为8和3 s;热氧化形成绝缘层;溅射50 nm Ti黏附阻挡层和1μm Cu种子层;使用硫酸铜和甲基磺酸铜体系电镀液电镀填充通孔,比较了双面电镀和自下而上电镀工艺;最终获得了硅片厚度370μm、通孔直径60μm TSV加工工艺。测试结果证明:样品TSV无孔隙;其TSV电阻值小于0.01Ω;样品气密性良好。     

Effects of dislocations in silicon transistors with implanted bases

Silicon bipolar transistors have been made by substituting a shallow boron implantation for the standard base deposition used in the manufacture of integrated circuits. This was followed by a high-temperature oxidation drive-in, and the transistor structure completed with a standard phosphorus deposition and drive-in. The implantations were performed through oxides with thicknesses in the range 0.08–0.17 μm. For the 0.17 μm transistors, the electrical characteristics were comparable with standard diffused transistors, while for the 0.08 μm transistors low gains and high emitter/base and collector/base leakages were obtained. For the latter transistors, etching and TEM studies revealed a dislocation network in the emitter region with a small fraction (10^?3) of the dislocations looping down to intersect the emitter/base and collector/base junctions. The poor electrical characteristics are explained in terms of the looping dislocations, and a mechanism is suggested to describe how the dislocations form.     

Evaluation of lateral diffusion factor in silicon from subthresholdcurrent in short-channel vertical SIT test structure

A measurement method for the evaluation of the lateral diffusion factor of deep implanted regions in lightly doped material is proposed. The method is based on measurements of the subthreshold current versus drain voltage in vertical static induction transistor (SIT) devices. The subthreshold current is very sensitive to SIT channel width and hence to lateral diffusion of the gate regions, as shown by two-dimensional numerical analysis. Experimental results obtained for test structures fabricated with different boron doses and the same drive-in treatment indicate a lateral diffusion factor of 64% for a typical drive-in process     

玻璃平面波导的热键合制备与界面扩散研究

铒镱共掺磷酸盐玻璃平面波导在散热和抑制非线性效应方面具有独特优势,可开发作为近红外1.5 μm高平均功率固体激光器的增益介质,具有重要意义。文中应用光胶热键合方法制备铒镱共掺磷酸盐玻璃平面波导,研究了预键合阶梯升温过程对键合质量的影响。通过电子探针表面分析（EPMA）得到键合温度和键合时间对键合界面分子扩散层厚度的影响,并根据Fick第二定律,探讨了一维等效假设下的芯层玻璃中的Yb3+扩散机理,建立了热键合过程中的固-固界面分子扩散模型。最终通过选择最优的热处理工艺参数,得到了键合质量良好且键合强度达到11.63 MPa的芯层厚度为100 μm的三明治结构平面波导。     

Effects of dislocations in silicon transistors with implanted emitters

Silicon bipolar transistors have been made by substituting a shallow phosphorus implanation for the standard emitter deposition used in the manufacture of linear integrated circuits. The implantation was followed by a high temperature heat treatment (drive-in), which caused the implanted ions to diffuse deeper into the semiconductor to give emitter/base junction depths of typically 1.8 μm. When the high temperature heat treatment was performed in an oxidising atmosphere, the resulting transistors had lower gains and higher emitter/base leakages than the comparable standard diffused transistors. However, if an 1180°C drive-in, in an inert atmosphere, was performed prior to the oxidation drive-in, high gains and low emitter/base leakages were obtained. Alternatively, if the oxidation drive-in was omitted, and instead an inert drive-in performed at any temperature between 1000 and 1180°C, high gains and low emitter/base leakages were again obtained. Etching and TEM studies revealed that the low gains and high emitter/base leakages were again obtained. Etching and TEM studies revealed that the low gains and high emitter/base leakages were caused by emitter edge dislocations intersection the emitter/base junction around the perimeter of the emitter. A mechanism is suggested to describe the formation of the emitter edge dislocations.     

Optical properties of Zn-diffused InP layers for the planar-type InGaAs/InP photodetectors

Zn diffusion into InP was carried out ex-situ using a new Zn diffusion technique with zinc phosphorus particles placed around InP materials as zinc source in a semi-closed chamber formed by a modified diffusion furnace.The optical characteristics of the Zn-diffused InP layer for the planar-type InGaAs/InP PIN photodetectors grown by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL) measurements.The temperature-dependent PL spectrum of Zn-diffused InP samples at different diffusion temperatures showed that band-to-acceptor transition dominates the PL emission,which indicates that Zn was commendably diffused into InP layer as the acceptor.High quality Zn-diffused InP layer with typically smooth surface was obtained at 580 ℃ for 10 min.Furthermore,more interstitial Zn atoms were activated to act as acceptors after a rapid annealing process.Based on the above Zn-diffusion technique,a 50μm planar-type InGaAs/InP PIN photodector device was fabricated and exhibited a low dark current of 7.73 pA under a reverse bias potential of-5 V and a high breakdown voltage of larger than 41 V (I ＜ 10 μA).In addition,a high responsivity of 0.81 A/W at 1.31 μm and 0.97 A/W at 1.55 μm was obtained in the developed PIN photodetector.     

固结磨料研磨硫化锌的亚表面损伤预测分析

研磨抛光后产生的工件亚表面损伤是评价工艺优劣及确定加工余量的主要参考,因此对亚表面损伤准确的预测有助于提高加工效率。采用离散元法对典型的软脆材料硫化锌固结磨料研磨过程中产生的亚表面损伤进行模拟,预测不同粒径金刚石加工工件后的亚表面微裂纹层深度。利用角度抛光法将工件抛光出一个斜面,作为亚表面损伤观测平面,通过盐酸的腐蚀使亚表面微裂纹显现,在金相显微镜下寻找微裂纹消失的终点位置并转换成亚表面微裂纹层深度,对仿真结果进行实验验证。结果表明:粒径为5、15、25、30 μm的磨粒造成的亚表面微裂纹层深度预测值分别为2.28、3.62、5.93、7.82 μm,角度抛光法实测值分别为2.02、3.98、6.27、8.27 μm。以上结果表明磨粒粒径对硫化锌亚表面损伤情况有很大的影响,随着磨粒粒径的增大,亚表面微裂纹深度增加,微裂纹数量增多。离散元法预测值与实测值偏差范围处在5%~15%之间,利用离散元法能有较为准确的预测软脆材料硫化锌加工后的亚表面损伤情况,为其研抛工艺的制定提供参考。     

A formula for the concentration profile of a buried layer with back diffusion

A simple formula allows an accurate dopant concentration profile to be calculated for a Gaussian buried layer with back diffusion into an epitaxial layer. The formula is valid when the drive-in diffusion is dominant, when the back diffusion is dominant, and for intermediate cases.