化学汽相淀积耐熔金属及其硅化物

本文综述了化学汽相淀积耐熔金属及其硅化物研究方面的最新进展,并对它们进行了讨论。     

A novel silicide nanopatterning method for the fabrication of ultra-short channel Schottky-tunneling MOSFETs

A novel nanometer patterning technique was developed to pattern epitaxial CoSi₂ layers and to fabricate Schottky-tunneling MOSFETs. The nanopatterning method is based on the local oxidation of silicide layers. A feature size as small as 50 nm was obtained for 20 nm epitaxial CoSi₂ layers on Si(100) after patterning by local rapid thermal oxidation in dry oxygen. A Schottky-tunneling MOSFET with epitaxial CoSi₂ Schottky contacts at both the source and the drain was fabricated using this nanopatterning method to make the 100 nm gate. The device shows good I–V characteristics at 300 K.     

Electroless deposition and silicidation of Ni contacts into p-type Porous Silicon

Porous Silicon (PS) has attracted much attention since the discovery of its photo luminescent behavior. It has also been used for various other applications such as electroluminescent light emitting-diodes (LEDs), photodetectors and solar cells. For such devices, it is important to make good metallic Ohmic contacts to the PS in order to maximize the efficiency. In order to produce buried contacts, barrier layers, Schottky devices, etc. in PS, it is advantageous to deposit metal that covers not only the surface of the porous layer, but also the inside walls and the bottom of the pores. In this work experiments were performed to examine the morphology and properties of electroless deposition of Nickel into p-type PS and subsequent formation of Nickel silicide after heat treatment. Circular PS samples of 6 mm diameter were produced by anodizing p-type Silicon wafers for 15 min and were subsequently plated with Ni using three different plating baths. The pores are on average 20 μm deep and 4 μm wide. Two samples of each type were heat treated in an nitrogen atmosphere for one hour at 400 and 600°C respectively to produce Nickel silicide. Reference samples were made by means of electron beam evaporation of Ni. SEM micrographs show that the best pore coverage was achieved using the Ni plating bath containing hypophosphite. I–V characterization shows that different rectifying and Ohmic contacts can be formed between electroless deposited Ni and PS depending on the conditions of the heat treatment. XRD and EDX characterizations show that both the NiSi and Ni₂Si phases exist in the sample at the same time.      

钛离子注入硅薄层硅化物结构和特性

用大束流密度的钛金属离子注入硅,能够直接合成性能良好的薄层硅化物,随束流密度的增加,硅化钛生长,薄层硅化物的薄层电阻（Ｒｓ） 明显下降,当束流密度（Ｊ）为０－７５Ａ／ｍ２ 时,Ｒｓ 达到最小值１６Ω／□,电阻率达到０－６４μΩ·ｍ 。经过１０５０ ℃快速退火２０ｓ 后,Ｒｓ 可下降到２－２Ω／ □,说明退火可进一步改善硅化钛的质量。扫描电子显微镜观察表明,枝状连续的硅化物已经形成。Ｘ衍射分析表明,注入层中形成了ＴｉＳｉ和ＴｉＳｉ２ 。背散射分析表明,其薄层厚度为８０ｎｍ 。利用ＭＥＶＶＡ金属离子注入,可获得直径达到Φ５００ｍ ｍ 注入斑点。     

难熔金属及硅化物薄膜特性研究

对难熔金属及其硅化物的形成、特性进行了研究。采用溅射难熔金属、热硅化反应的方法，解决了ＶＬＳＩ工艺中由于ＭＯＳ电路图形尺寸缩小带来的栅电阻增大的问题；采用硅化物阻挡层和Ａ１多层金属布线方法，解决了欧姆接触和铝的电迁移问题。     

Novel silicide BaPt5Si12: Crystal structure and physical properties

BaPt₅Si₁₂ has been synthesized by argon arc melting the elements. The structure was solved by direct methods from Kappa CCD intensity data. The novel silicide crystallizes in a unique monoclinic structure type: space group C2/m; a = 0.61327(2) nm, b = 3.23481(8) nm, c = 0.61180(1) nm, β = 90.130(2)°. The structure of BaPt₅Si₁₂ is characterized by Pt atoms, which are all arranged in planes parallel x–z resulting in tetrahedral coordination for Si1, Si2, Si3 and Si4 atoms and more complex distorted polyhedra around Si5 and Si6 atoms. Three voids were encountered in the structure at the centres of an Achimedian antiprism and two cube-octahedra. These voids do not show any residual electron densities. BaPt₅Si₁₂ turns out to be metallic; no phase transitions are found within the temperature range from 300 mK to 300 K. The overall resistivity is rather large, presumably a consequence of the voids in the crystal structure. Additionally, the quite complex crystal structure gives rise to intricate phonon modes.     

W阻挡层对Al/TiSi_2/Si接触系统热稳定性的影响

用X射线衍射及I—V测量技术研究了W在Al/TiSi_2/Si接触系统中的作用,并与不加W阻挡层的情况作了比较。热稳定性的研究表明:在高达100℃退火时,W阻挡层能够阻止Al与TiSi_2的完全反应。对Al/W/TiSi_2/Si接触二极管的I—V测试表明,在480℃以内退火,势垒高度变化不大。当退火温度达500℃时,Si通过TiSi_2层扩散至W阻挡层而使之失效.     

Nitrogen impurity effects on nickel silicide formation at low temperatures - New “nitrogen co-plasma” approach

Nickel based silicide films were prepared by annealing nickel-platinum layers deposited on n doped Si substrates. We report on the evolution of the phase formation and the redistribution of contaminants on blanket wafers during silicide formation as a function of the nitrogen gas flow introduces during Ni(Pt) deposition. Nitrogen incorporation creates a contamination as-deposited layer which modifies phase formation and changes nickel diffusion. Nitrogen is not incorporated in silicide formed. After a second anneal, the monosilicide forms excepted for high nitrogen quantity introduced where the Ni₃Si₂ is always observed. Monosilicide thermal stability is also improved by nitrogen co-plasma.     

Phase formation and texture of nickel silicides on Si1−xCx epilayers

We investigated the phase formation and texture of nickel silicides formed during the reaction of 10 nm sputter deposited nickel with Si_1−xC_x epitaxial layers on Si(1 0 0) substrates, having a carbon content between 0 and 2.5 atomic percent. It was found that both the formation temperature as well as the texture of the metal-rich phases is influenced by the amount of carbon in the Si_1−xC_x layer. To determine the influence of the location of the carbon during the silicidation process we also investigated the reaction of 10 nm nickel on Si(1 0 0) substrates, where carbon was either alloyed in the nickel layer or deposited as an interlayer at the interface between the nickel and the substrate. Depending on the location of the carbon, a different thermal stability of the layer was found.     

Significance of the interface regarding magnetic properties of manganese nanosilicide in silicon

Magnetic properties of manganese (Mn) nanosilicide embedded in thin silicon-on-insulator (SOI) layers are investigated. Mn nanosilicide formed by Mn⁺ ion implantation into a thin SOI layer followed by a thermal annealing at 600-900 °C shows soft ferromagnetism or superparamagnetism at 5 K. A monotonic decrease of the saturation magnetization is observed with increasing temperature for post implantation annealing and consequently with increasing mean particle size of nanosilicide. In addition, the magnetization is found to be enhanced when the Si surrounding the Mn nanosilicide is selectively removed. These results indicate that the magnetic moment indeed arises from the nanosilicide and is sensitive to the interface conditions.