硅中离子注入硼的异常扩散

本工作用不同的Si~+预注入能量,改变注入损伤分布与离子注入硼杂质分布的相对位置,观察快速热退火中注入损伤对硼异常扩散的影响.结果表明,引起注入硼异常扩散的是点缺陷,而不是硼间隙原子的快扩散.而注入损伤中的点缺陷和簇团分解释放的点缺陷是驱动硼异常扩散的因素之一.如果注入损伤形成了扩展缺陷,那么扩展缺陷重构和分解将发射点缺陷,这是驱动硼异常扩散的另一个因素.     

多晶硅膜离子注入和扩散掺杂制备浅结的研究

本文对多晶硅膜离子注入掺杂和扩散掺杂制备浅发射结进行了实验研究。针对新型薄发射极晶闸管特性改善对薄发射极参数的要求,重点研究了采用不同方法时退火条件对薄发射区掺杂剖面、结深以及杂质总量的影响。管芯研究结果表明,在适当的退火条件下,离子注入掺杂制备浅结是改善器件特性较为理想的方法。     

激光对硅片掺杂和退火的研究

集成电路正向高速、高集成度、高可靠性、低成本和低功耗方向发展,正在按比例缩小单元尺寸,因此迫切需要微细加工、薄层外延、低温浅结掺杂。微波二极管、晶体管和太阳电池也需要突变结掺杂,浅结扩散。离子注入虽然已成为低温掺杂的重要方法,但必须解决它所引起的晶格损伤并使注入杂质电激活。我们试图用激光掺杂来制造浅结器件,并做了两个实验。 第一个实验是涂层掺杂。用这种方法可以制造零点几微米的浅结二极管,这一结果对研制微波二极管和浅结集成电路具有重要意义。第二个实验是用激光去退火涂层热扩散片。结果表明,激光退火后,高表面浓度扩散片进一步电激活,使表面掺杂浓度更高;而低表面浓度扩散片由于激光退火时进行再分布,使表面浓度降低,方块电阻上升。     

硼扩散源及其在半导体器件中的应用

在半导体器件工艺中,多数情况是在硅衬底中掺 p 型或者 n 型杂质形成 pn 结。而最基本的 pn 结形成方法,一般采用杂质的热扩散法。通常,这种扩散工艺是由预沉积和再扩散两步工序组成的。首先是预沉积工序,它是在硅表面形成浅的高浓度杂质扩散区,其次是再扩散工序,它是使结更深地向硅衬底内推进,控制表面杂质浓度。认为控制了这个杂质浓度和结深就确定了半导体器件的性能,这种说法也并不过分。而且还可以说,预沉积将大大影响扩散的好坏。因此,本文简要说明一下关于预沉积中 p 型杂质(硼)扩散源的情况。同时,介绍一下最近 Owens-Illinois 公司研究的新的硼扩散源“Boro+~(TM)”(以下省略 TM)的优点。     

硼扩散源及其在半导体器件中的应用

在半导体器件的制造工艺中,向硅衬底中掺以P型或N型杂质形成PN结的时候居多,但是,本文应用的是形成PN结最基本的方法——杂质热扩散法。通常,这种扩散工艺由淀积和推进扩散二个阶段组成。首先,在淀积工艺中,在硅表面形成浅的高浓度杂质扩散区域,紧接着在推进扩散工艺中使结向更深的硅衬底内部浸透,控制表面杂质浓度。可以说,这种杂质浓度的控制和结深的控制左右着器件的性能。进而,这种扩散的好坏受到淀积工艺相当大的影响。因此,本文在说明了淀积工艺中P型杂质硼源概况的同时,着重介绍一下最近Owens-Illinois公司研究的新硼扩散源“硼~(+TM)(以下TM略去)的特点。     

100 nm P型超浅结制作工艺研究

介绍了一种P型超浅结的制作工艺。该工艺通过F离子注入和快速热退火技术相结合,获得了比较先进的100nm以内的P型超浅结;重点研究了影响超浅结形成的沟道效应和瞬态增强扩散效应;详细介绍了制作过程中对沟道效应和瞬态增强扩散效应的抑制。     

用化学汽相淀积钨和石墨快速退火降低接触电阻率

本文报道了用选择性低压化学汽相淀积钨和石墨快速退火降低金属与扩散形成的n~+、p~+浅结的接触电阻率.发现硼扩散或磷扩散浓度以及退火温度对接触电阻率都有影响,钨硅之间无明显的相互扩散.采用这种技术,钨与n~+、p~+硅的接触电阻率分别低达(1.5～4)×10~(-7)和(1～3)×10~(-7)Ω·cm~2.但与掺杂浓度较低的掺硼硅的接触电阻率较大.     

退火过程中RP缺陷模型及数值模拟

根据一维动力学方程,提出了RP缺陷的演化模型,用于描述离子注入后硼杂质分布在退火过程中出现异常变化的物理现象.通过分析发现缺陷随退火时间呈指数变化,根据变化的时间常数与RP缺陷对间隙原子束缚能的大小有关的原理,提出RP缺陷对间隙原子的束缚能为2.41eV.将该模型模拟硼杂质随退火时间的分布时,得到缺陷的分布与硼原子的分布变化趋势一致,且变化的时间常数相近,这给出了退火中硼出现异常分布的一种新的解释.     

集成电路制备中金属杂质与微缺陷的自吸除

用高温扩散法制备集成电路,结区会造成金属杂质聚集与晶体缺陷大量导生,这将导致结电特性降低和集成电路失效。本文通过实验分析了在集成电路制备中快速扩散金属杂质和晶体缺陷的一些重要规律特性。根据这些规律特性和双极型集成电路制备的工艺特点,对扩散版图进行了特殊设计;实现了电路制备过程中对快速扩散金属杂质与微缺陷的自吸除,对提高集成电路成品率、产品质量和减少失效均获得了显著效果。文中最后还对浓硼区吸除微缺陷的机理模型进行了探讨。     

硼和磷离子注入硅中的异常载流子剖面分布

观察了硼和磷离子注入 Si 中的载流子浓度剖面分布和异常增强扩散。将不同注入能量、不同剂量、常规退火和快速退火得到的结果进行了此较。结果表明:(1)对剂量小于或等于10~(14)cm~(-2)的硼离子注入,没观察到异常的载流子剖面分布。随着剂量的增加,将出现异常增强扩散尾;(2)不管退火方法如何,在磷离子注入中观察到了异常的载流子剖面分布和增强扩散尾。     

The effect of ion-implantation damage on dopant diffusion in silicon during shallow-junction formation

Low-thermal-budget annealing of ion-implanted BF ₂ ⁺ , P, and As in Si was studied for shallow-junction formation. Implant doses were sufficient to amorphize the silicon surface region. Low-temperature furnace annealing and rapid-thermal annealing of ionimplanted boron, phosphorus and arsenic in silicon exhibit a transient enhanced diffusion regime resulting injunction depths considerably deeper than expected. The origin of this transient enhanced diffusion is the annealing of ion-implantation damage in the silicon substrate. We have found that point-defect generation during the annealing of either shallow end-of-range damage or small clusters of point defects dominates the transient enhanced diffusion process depending upon the annealing temperature and time. The net effect of damage annealing is to reduce the activation energy for dopant diffusion by an amount equal to the activation energy of the supersaturation of point defects in silicon. Models which can describe the transient enhancement characteristics in dopant diffusion during both furnace and rapid-thermal annealing of these implants are discussed.     

A model for boron short time annealing after ion implantation

A simulation model is proposed for boron diffusion in silicon. It is especially useful for analyzing the short time annealing process subsequent to ion implantation. This model takes into account nonequilibrium diffusion and reactions of point defects and defect-dopant pairs, considering their charge states, and the dopant inactivation by the introduction of a boron clustering reaction. It is assumed that the boron-interstitial-silicon pair (BI) is a dominant diffusion species that contributes to the total boron diffusion. A primary model parameter, the binding energy of BI, is determined and used to reproduce the equilibrium gaseous source diffusion data. Using a single set of reasonable parameter values, the model covers not only the equilibrium diffusion conditions, from intrinsic, but also the nonequilibrium postimplantation diffusion. Experimental boro distribution profiles can be accurately reproduced. It is shown that the time constant for the BI dissociation reaction rules the transient behavior of boron diffusion enhancement during postimplantation annealing     

预非晶化硅中注入硼的异常扩散

预非晶化硅中,在非晶区和损伤区之间有一重损伤层存在,其边缘清楚,厚度约为20nm,包含有大量的扩展缺陷。它阻挡了尾部损伤区内簇团分解放出的硅间隙原子向非晶区扩散,大大削弱了非晶区内注入硼的异常扩散。选用条件适当的二次硅离子注入,使重损伤层加重加厚,从而完全阻止了非晶层内硼的异常扩散。本文在实验上为重损伤层阻止非晶区内硼异常扩散的模型提供证明。     

Diffusion and doping issues in germanium

This paper gives a review on self- and dopant diffusion in germanium (Ge) under thermal equilibrium and irradiation conditions and specifies the underlying mechanisms of diffusion and the point defects involved. Diffusion in Ge under thermal equilibrium conditions is mainly controlled by vacancies. However, Ge interstitials mediate the diffusion under concurrent annealing and irradiation. This is verified by the diffusion behavior of self-atoms, boron, phosphorus and arsenic under proton irradiation. The diffusion under irradiation is explained with the property of the Ge surface that is proposed to be an insufficient sink for Ge interstitials. As a consequence, a supersaturation of self-interstitials is established during irradiation, whereas the vacancy concentration is kept at thermal equilibrium. This explains that under irradiation the diffusion of self- and dopant atoms via self-interstitials becomes visible that is otherwise negligible under conventional annealing conditions. Our findings demonstrate ways to switch between vacancy and self-interstitial mediated diffusion and shows new strategies in the diffusion doping of Ge for technological applications.     

Model of boron diffusion from gas phase in silicon carbide

Boron diffusion from the gas phase in silicon carbide is described on the basis of a two-component model. “Shallow” boron, i.e., boron at silicon sites, is a slow component with a high surface concentration. Its diffusivity is proportional to the concentration of positively charged intrinsic point defects, which are presumably interstitial silicon atoms. “Deep” boron, i.e., impurity-defect pairs of boron-carbon vacancy, is a fast component with lower surface concentration. The ratio between the surface concentrations of the components depends on the pressure of silicon or carbon vapors in the gas phase. The diffusion and interaction of components are described by the set of diffusion-reaction equations. The diffusion retardation observed on the concentration-profile tail is related to the capture of impurity-defect pairs and excess vacancies by traps of background impurities and defects.     

Low-temperature furnace-grown reoxidized nitrided oxide gatedielectrics as a barrier to boron penetration

Reoxidized nitrided oxide (ROXNOX) gate dielectrics can be used to block the diffusion of boron into the MOS channel region. However, fixed oxide charge annealing can mask the effects of boron in the channel, a particularly important consideration for low-temperature gate oxides. The authors separate the effect of fixed charge annealing from the effect of boron diffusion and demonstrate that a low-temperature furnace-grown reoxidized nitrided oxide has a substantial advantage over conventional gate oxides in protecting the channel from boron over a wide range of annealing times and temperatures. They also address the issue of fixed charge annealing in low-temperature reoxidized nitrided oxides and present an approach to maintain acceptable gate dielectric quality while preserving a low D-t product for integration into a scaled dual-gate CMOS process     

Estimation of effective diffusion time in a rapid thermal diffusionusing a solid diffusion source

Two-step rapid thermal diffusion (RTD) of phosphorus and boron using a solid diffusion source is described. From the application of the Boltzmann-Matano method to SIMS profiles of phosphorus and boron after RTD, it has been found that some additional correction terms to the effective diffusion time must be introduced. In the phosphorus diffusion case, the increment of the effective diffusion time due to the supersaturation of point defects during the cooling cycle is about 3 s. In the case of boron diffusion, the additional effective diffusion time is a strong function of diffusion temperature. This has been explained as the effect of initial growth of the boron-rich layer during the glass-transfer process. The introduction of additional correction terms to the effective diffusion time makes it possible to treat the RTD process in a similar manner to normal diffusion