Optimization of process conditions for the formation of hemispherical-grained (HSG) silicon in high-density DRAM capacitor

We have compared the capacitances of a conventional stacked capacitor and hemispherical-grained silicon (HSG-Si), in which the seeding method was applied to storage electrode of 64 Mbit dynamic random access memory (DRAM) through Si₂H₆-molecule irradiation and annealing for HSG-Si formation. Also, we considered the variation of the HSG-Si thickness due to the phosphorus concentration of storage poly-silicon in process condition and the effect of its thickness on the cell capacitance and failure occurrence, etc. We investigated the effect of the deposition temperature of amorphous poly-silicon on the HSG-Si formation. As a result, the optimum process conditions of the phosphorus concentration, the deposition temperature of storage poly-silicon and the HSG thickness in HSG formation are 3.5–4.5×10¹⁹ atoms/cm³, 530°C and 450 Å, respectively. It is found that the limit thickness of dielectric film of 64 Mbit DRAM capacitor according to the optimized process condition is 65 Å.     

纳米压痕和划痕法测定氧化硅薄膜材料的力学特性

为了研究不同制备工艺对材料力学性能的影响 ,选择了热氧化、LPCVD和PECVD三种典型工艺 ,在硅片上制备 1μm氧化硅薄膜。通过纳米压痕和划痕检测可知 ,热氧化工艺制备的SiO2薄膜的硬度和模量最大 ,LPCVD制备的样品界面结合强度高于PECVD。纳米压痕和划痕技术为此提供了丰富的近表面弹塑性变形和断裂等的信息 ,是评价微米薄膜力学性能的有效手段     

SiH2CL2-NH3-N2体系LPCVD Si3N4薄膜因素分析

以二氯甲硅烷和氨气分别作为低压化学气相淀积(LPCVD)氮化硅(Si3N4)薄膜的硅源和氨源,以高纯氮气为载气,在热壁型管式反应炉中反应生成Si3N4薄膜.考察了工作压力、反应温度、气体原料组成等因素对Si3N4薄膜淀积速率的影响.结果表明Si3N4薄膜的生长速率随着工作压力的增大单调增大,随着原料气中氨气和二氯甲硅烷的流量之比的增大单调减小.随着反应温度的升高,淀积速率逐渐增加,在840 ℃附近达到最大,随后迅速降低.在适当的工艺条件下,制备的Si3N4薄膜均匀、平整.较低的薄膜淀积速率有助于提高薄膜的均匀性,降低薄膜的表面粗糙度.     

氯基条件下4H-SiC衬底的同质外延生长研究

利用课题组自主研发的热壁低压化学气相沉积(HWLPCVD)系统,在朝[11-20]方向偏转4°的(0001)Si面4H-SiC衬底上进行快速同质外延生长,研究了生长温度及氯硅比(Cl/Si比)对外延生长速率的影响机理.研究发现,外延生长速率随生长温度的提高呈线性增加,而Cl/Si比的改变对生长速率的影响不大.文章进一步探究了Cl/Si比对4H-SiC外延层表面缺陷的影响.较低的Cl/Si比(0.4～2)可以减少或消除三角缺陷,Cl/Si比较高(大于5)时,表面质量反而下降,因而,适当的Cl/Si比对于获得表面形貌良好的4H-SiC外延层至关重要.     

Heteroepitaxial growth and characterization of 3C-SiC films on on-axis Si (1 1 0) substrates by LPCVD

Cubic SiC (3C-SiC) film has been deposited on Si (1 1 0) substrate by the low pressure chemical vapor deposition (LPCVD) with gas sources of SiH₄, C₃H₈ and carrier gas of H₂. The 3C-SiC crystalline film can be confirmed through the observations using reflection high-energy electron diffraction (RHEED) images. The X-ray diffraction (XRD) pattern and the rocking curve indicate that the (1 1 1) plane of SiC film is parallel to the surface of the Si (1 1 0) substrate and the film is of high crystallinity. The results of the field emission scanning electron microscope (FESEM) images show that the film has smooth surface morphology. Transmitted electron diffraction (TED) pattern and high resolution transmission electron microscope (HRTEM) image further confirm the high quality of the film.     

Characterization of surface profiles of LPCVD silicon nitride films by RBS profile

Abstract

A Rutherford backscattering spectrometry (RBS)‐profile was applied to the characterization of the surface profile of silicon nitride films prepared by low pressure chemical vapor deposition (LPCVD). This method detected inhomogeneity in the silicon nitride films and demonstrated Si‐richness near the interface. This method was also used to study the silicon nitride profiles associated with bird's beak formation in VLSI devices. This paper presents a scheme for an auto‐search routine for an RBS‐profile program. The potential of the RBS‐profile method for the characterization of LPCVD silicon nitride films are demonstrated.     

LPCVD多晶硅薄膜发雾的形成与消除

LPCVD多晶硅薄膜发雾对CMOS器件性能有重大影响,文章分析了多晶硅薄膜发雾的形成机理与影响因素,指出了低温、低压以及保持气路系统的清洁是消除多晶"发雾"的有效措施。根据多晶硅薄膜雾状斑点的形状与分布位置,对硅片表面缺陷的来源进行了分类,并从清洗工艺、污染物成分分析、前道工序等方面提出了相应的解决措施。     

Growth,magnetic properties and the effect of cobalt addition in metal-organic chemical vapour deposited (MOCVD) gamma iron oxide thin films for magnetic recording applications

The present study aims at investigating MOCVD technique for the deposition of magnetic oxide thin films using volatile metal-organic compounds as source material. A three-step scheme has been described to form γ-Fe₂O₃ phase starting from α-Fe₂O₃ films as-deposited in optically heated atmospheric cold wall CVD reactor. Growth of γ-Fe₂O₃ in a two-step process has been performed by depositing Fe₃O₄ phase directly by resistively heated low-pressure CVD (LPCVD) technique. Role of substrate temperature in controlling the oxidation leading to direct formation of metastable γ-Fe₂O₃ phase (single-step scheme) by atmospheric CVD technique has been described. A new mode of introduction of cobalt in the film, namely heterogeneous dispersion of cobalt in the γ-Fe₂O₃ matrix, has also been described. Crystallographic structure, microstructure and magnetic properties of the films have been studied in detail. Biaxial vector coil and high-temperature magnetic studies were carried out for determining the nature of anisotropy in the γ-Fe₂O₃ film. Growth of γ-Fe₂O₃ films in different schemes have been discussed from the studies of growth kinetics in a cold-and hot-wall-type reactor chambers.     

Rapid thermal chemical vapor deposition of germanium on silicon and silicon dioxide and new applications of ge in ULSI technologies

In this study, low pressure chemical vapor deposition of pure germanium on silicon and silicon dioxide has been considered for new applications in future ultra large scale integration (ULSI) technologies. Germanium depositions were performed in a lamp heated cold-wall rapid thermal processor using thermal decomposition of GeH₄. It is shown that Ge deposition on Si can be characterized by two different regions: a) at temperatures below approximately 450° C, the deposition is controlled by the rate of surface reactions resulting in an activation energy of 41.7 kcal/mole. b) Above this temperature, mass transport effects become dominant. The deposition rate at the transition temperature is approximately 800 Å/min. It is shown that Ge deposition on SiO₂ does not occur, even at temperatures as high as 600° C, resulting in a highly selective deposition process. Selectivity, combined with low deposition temperature makes the process very attractive for a number of applications. In this work, it is shown for the first time that selective Ge deposition can be used to eliminate silicon consumption below the gate level during the silicidation of the shallow source and drain junctions of deep submicron MOSFETs. In addition, a new in situ technique has been developed which allows polycrystalline germanium (poly-Ge) deposition on SiO₂. In this work poly-Ge has been considered as a low temperature alternative to polycrystalline silicon (poly-Si) in the formation of gate electrodes in single-wafer manufacturing where low-thermal budget processes are most desirable.