离子注入和热退火工艺对应变Si材料应力影响研究

应变Si技术是延续摩尔定律最有效技术之一,论文重点研究了离子注入和热退火过程对应变Si材料中应力的影响,开展了不同离子注入类型、能量和剂量,以及热退火温度和时间对应变Si材料特性影响的实验,并应用拉曼测试对实验结果进行了分析,结果表明：在剂量小于5E14cm-2时,应变Si材料中的应力几乎不随离子注入的能量与剂量变化;应变Si材料在1000℃以下,在60min以内热退火,应力几乎不随温度与时间的变化而变化。     

Si1-xGex/Si应变材料的生长及热稳定性研究

利用分子束外延（MBE）技术生长了Ge组份为0.1-0.46的Si1-xGex外延层。X射线衍射线测试表明，SiGe/Si异质结材料具有良好的结晶质量和陡峭界面，其它参数与可准确控制。通过X射线双晶衍射摆曲线方法，研究了经700℃、800℃和900℃退火后应变SiGe/Si异质结材料的热稳定性。结果表明，随着退火温度的提高，应变层垂直应变逐渐减小，并发生了应变弛豫，导致晶体质量退化；且Ge组分越小，Si1-xGex应变结构的热稳定性越好；室温下长时间存放的应变材料性能稳定。     

Strain relaxation in silicon ion molecular beam epitaxy on silicon (001) substrates during aging

Silicon strained epitaxial films were grown on Si (001) substrates by low energy ion beam assisted molecular beam epitaxy. Films grown in the range of 450– 550°C with concurrent Ar⁺ ion bombardment (100 eV) were characterized using x-ray diffraction and transmission electron microscopy and found to be disloca-tion free and ununiformly strained. During aging, the strained layers stay stable until 500°C. Relaxation of most of the strain occurred at temperatures of 500-650°C. At higher aging temperatures, the strained layers relaxed by the formation of dense dislocation structures.     

Si_(1-x)Ge_x/Si多层异质外延结构的研究

对制作的 Ｓｉ１－ｘＧｅｘ／Ｓｉ多层异质外延结构进行了研究。并对其做了反射高能电子衍射（ＲＨＥＥＤ）、Ｘ射线衍射（ＸＲＤ）和扩展电阻（ＳＲ）等测量,给出了利用这种结构研制出的异质结双极晶体管（ＨＢＴ）的输出特性曲线。     

Suppression of twin formation in CdTe(111)B epilayers grown by molecular beam epitaxy on misoriented Si(001)

CdTe(lll)B layers have been grown on misoriented Si(001). Twin formation inside CdTe(lll)B layer is very sensitive to the substrate tilt direction. When Si(001) is tilted toward [110] or [100], a fully twinned layer is obtained. When Si(001) is tilted toward a direction significantly away from [110], a twin-free layer is obtained. Microtwins inside the CdTe(111)B layers are overwhelmingly dominated by the lamellar twins. CdTe(111)B layers always start with heavily lamellar twinning. For twin-free layers, the lamellar twins are gradually suppressed and give way to twin-free CdTe(111)B layer. The major driving forces for suppressing the lamellar twinning are the preferential orientation of CdTe[11-2] along Si[1-10] and lattice relaxation. Such preferential orientation is found to exist for the CdTe(111)B layers grown on Si(001) tilted toward a direction between [110] and [100].     

Implantation of si under extreme conditions: The effects of high temperature and dose on damage accumulation

The accumulation of lattice damage in Si(100) during ion irradiation at extreme dose and temperature was investigated. Irradiation above the ion-induced, crystal-to-amorphous transition temperature (∼200°C) enabled damage growth to be studied to arbitrarily high dose. Electron microscopy and Rutherford backscattering spectrometry were used to characterize the growth of damage under these extreme conditions, as well as its microstructural evolution. These observations are correlated both to irradiation conditions and the effects of ionsolid chemistry associated with the use of atomic ions dissimilar to the bulk atoms. These chemical effects are isolated by comparing results for Si⁺⁻ with P⁺⁻ ion irradiations, and As⁺⁻ with Ge⁺⁻irradiations. Each combination includes an isoelectric and dopant ion of nearly identical mass for separating out the effects of the ion-solid chemistry. A mechanism to account for the formation of the ioninduced morphology under extreme irradiation conditions is presented.     

In-situ spectroscopic ellipsometry of HgCdTe

An in-situ spectroscopic ellipsometer has been equipped on a molecular beam epitaxy system to improve control of HgCdTe growth. Using this device, in-situ analysis of composition, growth rate, and surface cleanliness were monitored. A real time model which determined the compositional profile was used. The ellipsometer was employed to give in-situ real time control of the growth process.     

Si(100)和Si(111)衬底上的同质分子束外延

用超高真空电子束蒸发系统进行了硅的同质分子束外延.发现采用适当的表面化学处理方法,然后在超高真空中加热,可以在较低温度下(800—814℃)获得清洁和平整的有序表面.Si(100)和Si(111)的外延分别在520℃和714℃进行,外延膜的结构和电学特性良好.     

Tilted superlattice composition profile determined by photoluminescence and thermal disordering

The composition profile of an (AlAs)_1/2(GaAs)_1/2 tilted superlattice is characterized for the first time. The tilted superlattice sample is thermally disordered, and the energy of the direct band gap photoluminescence peak is measured as a function of increasing layer interdiffusion. The shift in the photoluminescence peak energy after completely disordering the tilted superlattice is 39 meV. A theoretical model is used to simulate the change in band gap as a function of layer interdiffusion for several composition profiles. The profile that gives the best fit to the experimental data is chosen. The tilted superlattice composition profile is found to be sinusoidal, varying from Al_0.40Ga_0.60As to Al_0.60Ga_0.40As.     

应变Si沟道CMOS中的离子注入工艺

为避免应变Si沟道(Strained Si channel)CMOS工艺中的高温过程,通过选择合适的离子注入能量和剂量,采用快速热退火(RTP)工艺,制备出适合做应变Si沟道CMOS的双阱及源漏.霍尔测试得表面电子迁移率为1117cm2/V·s,载流子激活率为98%;原子力显微镜测试表明应变Si表面RMS为110 nm;XRD测试虚拟衬底SiGe弛豫度达96.41%;源漏结击穿电压为43.64V.     

SiGe／Si HBT离子注入自对准的研究

介绍了离子注入技术自对准制作ＳｉＧｅ／ＳｉＨＢＴ的方法，分析了对器件特性的影响。     

LEC不掺杂半绝缘GaAs的热处理特性

本文对LEC不掺杂SI-GaAs的热处理特性进行了实验研究和分析。结果表明,As、Ga原子从表面挥发及缺陷的内扩散引起表面热蚀和热致导电层的形成。文章讨论了它们对注入层激活行为的影响。指出,采用本文设计的高温快速热处理结合压盖、InAs作过砷压源技术,可以获得满足注硅材料退火要求的SI-GaAs热处理特性。     

Phonon-resolved and broad photoluminescence in strained Si1−xGex alloy MBE layers

In the photoluminescence (PL) spectra of Si_1?xGe_x multi-quantum wells (MQW) grown by conventional solid source molecular beam epitaxy (MBE), phonon-resolved, near-bandgap transitions due to shallow dopant bound exciton or free exciton recombination were observed when the well thickness was less than 40–100Å, depending on x. Increasing the Si_1?xGe_x well thickness caused the emergence of a broad, unresolved PL peak ～120 meV lower in energy than the expected bandgap energy. Interstitial-type platelets, less than 15Å in diameter, were measured by plan view transmission microscopy to occur in densities that correlated well with the intensity of the broad PL peak. A platelet density of ～10⁸ cm^?2 per well was sufficient to completely quench the phonon-resolved PL. Etching experiments revealed that within a given MQW, the platelet density is lowest in the first grown well and progressively increases in subsequent wells with increasing strain energy density, indicating that platelet formation is strictly a morphological phenomenon and suggesting that a strain relaxation mechanism is in effect before the onset of relaxation by misfit dislocation injection.     

GaInP and AlInP grown by elemental source molecular beam epitaxy

We report on the use of a new, valved, solid phosphorus cracker source for the growth of phosphides by molecular beam epitaxy. The source avoids the relatively high expense and high level of toxicity associated with the use of phosphine gas and eliminates the problems commonly encountered in using conventional solid phosphorus sources. The source has been used to grow GaInP and AlInP lattice-matched to GaAs substrates. The quality of the materials reported here is comparable to the best materials grown by other techniques. Photoluminescence and Raman scattering measurements indicate that the resulting material has a high degree of disorder on the group III sublattice. The new source is shown to be a reliable and attractive alternative for the growth of these phosphide materials.     

Investigation of the interface region produced by molecular beam epitaxial regrowth

The interface region generated by molecular beam epitaxial regrowth has been studied in detail. Regrowth was carried out on epitaxial GaAs after a variety of realistic device processing steps. Combinations of wet chemical etching and ion milling with and without annealing were used with the objective of establishing the best procedure for integrated technologies during regrowth. Capacitance voltage measurements showed perturbations in the carrier profile corresponding to depletion and accumulation regions at the interface which are directly related to interface states at and around the regrowth interface. The measured concentration of the interface states are in the range 1.2 × 10¹⁰ to 7.05 × 10¹¹ cm⁻². The former is one of the lowest reported till date. The concentration of deep traps in the regrown layer and interface, observed by deep level transient spectroscopy, is much lower than the interface state density. Their contribution to carrier perturbation is insignificant, except in one case where an electron trap has a rather high concentration. Results of secondary ion mass spectroscopy indicate that the presence of carbon at the regrown interface is not principally responsible for creating the high resistivity interface region. Our data favor the concept of a disordered region created at the interface during regrowth. Interface state density and trap densities are much larger in the wet chemically etched samples, which is further supported by the results of temporal photoresponse measurements on junction photodiodes. The overall characteristics of the dry etched regrowth interfaces seem to be much more promising than the wet chemical etched ones. On leave from the Institute of Radiophysics and Electronics, The University of Calcutta, Calcutta 700 009, India.     

The control of size and areal density of InAs self-assembled quantum dots in selective area molecular beam epitaxy on GaAs (0 0 1) surface

The growth of InAs quantum dots (QDs) on GaAs (0 0 1) substrates by selective area molecular beam epitaxy (SA-MBE) with dielectric mask is investigated. The GaAs polycrystals on the mask, which is formed during growth due to low GaAs selectivity between dielectric mask and epitaxial region in MBE, strongly affect the distribution of InAs QDs on the neighbouring epitaxial regions. It is found that the GaAs polycrystalline regions strongly absorb indium during QD growth, confirmed by microscopic and optical studies. GaAs polycrystalline deposit can be reduced under low growth rate and high-temperature growth conditions. Almost no reduction in QD areal density is observed when there is minimal polycrystalline coverage of the mask.     

突变反型异质结及其双极晶体管的研制

文章对突变反型异质结的能带图、接触电势差和势垒区宽度进行了讨论和研究。同时，介绍了基于分子束外延(MBE)法生长的SiGe／Si结构的异质结双极晶体管(HBT)制造工艺，并给出了测试结果。     

Lattice mismatched InGaAs on silicon photodetectors grown by molecular beam epitaxy

In_0.5Ga_0.5As on silicon photodetectors, including three types of interdigitated-finger devices as well as linear photoconductors, were fabricated and measured. The InGaAs/Si structure was grown by molecular beam epitaxy and utilized a 100 Å GaAs intervening nucleation layer between the silicon substrate and the InGaAs layers, step-graded In_xGa_1?xAs layers, and an in-situ grown 40 Å thick GaAs surface layer, which substantially enhanced the metal-semiconductor barrier height (Φ_b = 0.67 V) for the InGaAs. Schottky diodes fabricated independently of the photodetectors had nearly ideal characteristics with an ideality factor (n) of 1.02 and a reverse breakdown voltage of 40 V. The interdigitated Schottky photodetectors showed dark currents between <3nA and 54 μA at a 3 V bias and initial photoresponse rise times in the range of 600 to 725 ps, comparable to similar InGaAs metal-semiconductor-metal photodetectors grown lattice matched on InP. The photoconductors fabricated in the same material had rise times in the range of 575 to 1300 ps, thus being slightly slower, and had dark currents of 7 to 80 mA. The responsivity of the photoconductors was typically greater than that of the diodes by a factor of five to fifteen. The results show potential for monolithic integration of InGaAs photodetectors on silicon substrates.     

在线离子注入机质量跟踪研究

本文报告以实验的方法，经过一年的工艺跟踪试验，对某型号在线运行十年的中能离子注入机的运行质量进行检测研究。用四探针法研究了中剂量（１×１０￣（１４）ｃｍ－２）注入样品的薄层电阻，发现最大偏差为２％；用Ｃ－Ｖ法测量了低剂量注入样品的表面浓度。检测结果表明，注入样品表面峰值浓度偏差为６％，但不同低剂量注入样品分辨力是可以的；同时发现，氧化后，未注入样品在退火前、后峰值浓度变化为７．４％；对试验样品原始数据也进行了测量。由此提出，集成电路成品率的提高有赖于整个加工线运行质量的可靠程度。