Papers by Keyword: Planarization

Abstract: Ultra smooth and defect-free 4H-SiC wafers are strongly demanded in the next-generation power semiconductor devices. However, such SiC substrates are relatively difficult to machine because of their mechanical hardness and marked chemical inertness. In this study, we attempt to polish 2-inch 4H-SiC wafers by our proposed method, which utilizes Fe particles and a hydrogen peroxide solution. The processed surface was observed by phase shift interferometric microscopy, Nomarski differential interference contrast microscopy and atomic force microscopy. These observational results show that the surface roughness was improved over the entire 2-inch wafer by our proposed method. These results offer useful information for preparing a smooth SiC wafer.

Abstract: We have developed a novel planarization method called catalyst-referred etching (CARE), which can planarize SiC substrates without the use of an abrasive. In this method, platinum is used as an oxidation catalyst. The surface of CARE-processed 4H-SiC (0001) substrates are atomically flat all over the wafer. It is found that the surface of CARE-processed substrates is composed of alternating wide and narrow terraces with single bilayer-height steps, regardless of the off-cut angle. This unique structure is induced by the differences in the chemical stabilities of the terraces.

Abstract: This study focuses on inorganic gas barrier material in the advanced process techniques of solar cell devices for planarization properties and sublimate defect reduction. The inorganic gas barrier material have been optimized and studied for excellent surface planarization property. The newest approach by excellent collaborations from both process and material has the planarization property on an irregular substrate such as the patterned steps, via and trenches to increase the depth of focus and pattering resolution. A remarkable reduction in via topography with 0.6 μm as a depth and 0.13 μm as a diameter has been achieved excellent thickness bias less than 50 nm in 220 nm blanket field thickness. In addition, the sublimate amount of the film obtained from the developed inorganic gas barrier material was low as compared with that of the film obtained from the referenced organic non-gas barrier material.

Abstract: The traditional solid alumina abrasive has been widely used in commercial slurries. But it is easy to cause polishing scratches due to its dense solid structure. The morphology of the abrasives can also impact on the chemical mechanical polishing (CMP) performances. To improve the CMP performances of the hard disk substrate, rods-like porous alumina and flower-like porous alumina abrasives were prepared and their chemical mechanical polishing behavior investigated. The results showed that the porous alumina abrasives with different morphologies exhibited lower topographical variations and surface roughness than solid alumina abrasives under the same testing conditions.

Abstract: Electropolishing, the anodic dissolution process without contact with tools, is a surface Treatment method to make a surface planarization using an electrochemical reaction with low current density. Stainless steel can be put various applications which require purity and high precision surface of products. The aim of this study is to investigate the characteristic of electropolishing effect for stainless steel workpieces. In order to analyze the characteristics of electropolishing effect, surface roughness and micro-burr size were measured in terms of machining conditions such as current density, machining time and electrode gap. The tendencies about improvement of surface roughness by electropolishing for stainless steel workpieces were determined.

Abstract: The processes for polishing a ZnO surface were investigated with the aim of establishing a process for obtaining an atomically flat surface with high crystalline quality. The defects in a layer undergoing mechanical polishing were monitored through photoluminescence measurements, and the purity of the polished surface was characterized by SIMS. An atomicallyfishing process.

Abstract: The model proposed integrates process parameters including pressure and velocity and other important input parameters including the wafer hardness, pad roughness, abrasive size, and abrasive geometry into the formulation to predict the material removal rate. Based on the deformation of hyper-elastic asperities attached to a linear-elastic pad, contact mechanism between the asperities and the wafer is analyzed. Micro-contact mechanism between the particle and wafer is proposed on the basis of elastic-plastic deformation theory. Material removal rate of single abrasive particle is calculated by the abrasive wear theory. The fluid effect in the current model is attributed to the number of active abrasives. Wafer scale material removal rate is analyzed in detail, which is agreed with the experimental results. The Preston’s coefficient, which has been determined empirically, is now given as a function of various processing variables, pad roughness, wafer material properties and slurry status.

Abstract: Catalyst-referred etching (CARE) is an abrasive-free planarization method. We used 3-inch and 2-inch 4H-SiC (0001) 4° off-axis substrates to investigate the processing characteristics that are affected by the substrate diameter. The surface roughness of the 3-inch substrate was extremely smooth over the whole substrate. The surface roughness and removal rate of the 3-inch substrate were approximately the same as those of the 2-inch substrate.

Abstract: We have developed a novel abrasive-free planarization method called catalyst-referred etching (CARE). A CARE-processed 8 deg off-axis 4H-SiC (0001) surface is investigated by cross-sectional transmission electron microscopy (TEM). The surface is composed of alternating wide and narrow terraces with single-bilayer-height steps, which are similar to the structure observed on a CARE-processed on-axis 4H-SiC (0001) surface. These results indicate that the structure appears on CARE-processed surfaces regardless of the off-cut angle.

Abstract: Electrochemical polish technology could enhance the chemo-mechanical polishing efficiency of copper material. During the electrochemical polishing process, both the components and operation parameters of electrochemical polish solution are the key factors influencing planarization ability. This work measured the surface topography and roughness of copper material after mechanical polish by an atomic force microscope (AFM), and added glycerol in different ratios to the phosphoric acid (85 wt %), which was the main composition of experiment solution. Electrochemical polish was conducted within the potential action range in passivation area, and the surface topography and roughness of copper material after electrochemical polish was measured by AFM. The difference in surface topography of copper material after electrochemical polish was compared as well.The experiment indicated that after electrochemical polish in pure phosphoric acid for 50 sec, the surface roughness of copper material obviously decreased from 6.921nm (Ra) to 0.820nm (Ra), and the planarization was more obvious with the increase of electrochemical polish time. The above results could appear in different electrolyte formulas, indicating that electrochemical polish was a good processing method for copper material planarization. This work also proposed the effect of analyzing the electrochemical polish time on planarization through planarization efficiency. Based on the analysis, the planarization efficiency was decreased with the increase of electrochemical polish time, which indicated that longer electrochemical polish time did not yield better result. This work also found that the surface is not only flattened, but also glossed after electrochemical polish.