Yu Li Sun

Progress of Research in Slicing Technology of Large-Scale Silicon Wafers

This paper introduces and summarizes the slicing technology of large-scare silicon wafers. And the research status of ID slicing, wire saw slicing and WEDM is summed up. Finally, this document indicates the direction of research and the development.

Mechanism of Brittle-Ductile Transition of Single Silicon Wafer Using Nanoindentation Techniques

Hardness, elastic modulus and scratch resistance of single silicon wafer are measured by nanoindentation and nanoscratching using a nanoindenter. Fracture toughness is measured by indentation using a Vickers indenter. The results show that the hardness and elastic modulus at a peak indentation depth of 100 nm are 12.6 and 166.5 GPa respectively. These values reflect the properties of the silicon wafer, the bulk material. The fracture toughness value of the silicon wafer is 0.74 Mpa·m1/2. The material removal mechanisms are seen to be directly related to the normal force on the tip. The critical load and scratch depth estimated from the scratch depth profile after the scratching and the friction profile are 138.64 mN and 54.63 nm respectively. If the load and scratch depth are under the critical values, the silicon wafer will undergo plastic flow rather than fracture. The critical scratch depth is different from that calculated from the formula of critical-depth-of-cut described by Bifnao et al and some reasons are given.

Study on Subsurface Damage after Fixed-Abrasive Lapping with Different Particle Size

Differential chemical etch method (DCEM) was employed to study the effect on the surface/subsurface damage depth of K9 glass lapped by different particle sizes of fixed diamond abrasives. The advantage of DCEM is that both the lapped and substrate samples are placed in the chemical etch at the same time to decrease or eliminate the effect of etching condition variation. K9 glasses are firstly fixed-abrasive lapped with 40, 28, 14 and 10μm diamond abrasives, respectively. Surface damages of K9 glass after FAL are measured by Microscopy. The results show that the corresponding subsurface damage (SSD) depths of K9 glass are 4.5, 3.4, 2.8 and 1.6μm when the fixed diamond abrasive particle size are 40, 28, 14 and 10μm.With the decreasing of diamond particle size, the SSD depth decreases obviously and surface quality of K9 glass is improved significantly.

Experimental Research on Cutting of Silicon with Fixed Diamond Wire Saw

The experimental research on silicon was reported in this paper. The surface roughness under the different workpiece feed speed and linear velocity of the wire saws is studied mainly in this experiment. The effects of the workpiece feed Vs and the linear velocity of the wire saws Vw were analyzed.

Computer Simulation on the Motion Tracks of Ice Fixed Abrasives Polishing

Ice fixed abrasives (IFA) polishing is a novel ultra-precision machining method. The motion tracks of abrasives during IFA polishing have an important effect on the quality of the machined silicon wafer. Firstly, the motion tracks of IFA polishing are theoretically analyzed in this paper. It is founded that the paths of any point in the IFA polishing pad relative to the wokpiece are a group of cycloids. Then, the motion tracks of single abrasive and multiple abrasives in the IFA polishing pad are simulated respectively. The results show that increasing the eccentricity is beneficial to the enlargement of the size range of polishing process. With the increasing of the speed ratio between the IFA polishing pad and the workpiece, the abrasive at higher speed can leave longer tracks on the workpiece than that at lower speed at the same time. The more the abrasives, the more uniform the mark density under the influence of more abrasives.

Temperature Distribution of IFA Polishing Single Silicon Wafer

The ice fixed abrasives (IFA) polishing is a potential polishing process in the semiconductor industry to realize superior surface finish and planarity for semiconductor wafers. The key question in IFA polishing is how to keep suitable ambient temperature and melting rate in production process in order to avoid premature failure of the IFA pad. In this paper, effects of ambient temperature (T), pressure in cylinder (Pc), rotary speed of IFA pad (v) and eccentricity of pressure head (e) on temperature distribution and melting rate of the IFA pad are researched. The results show that T should be kept at about 10 °C in order to control the melting rate of the IFA pad effectively and keep longer polishing time. And suitable Pc, e can be kept at 0.075 MPa or 0.1 MPa and 20 mm or 30 mm, respectively. In order to increase IFA polishing efficiency, the rotary speed of IFA pad can be increased appropriately. All the results provide the basis for choosing suitable processing parameters in IFA polishing.

The Analysis on the Stability of Diamond Wire Saw Cutting Process for the Silicon

. In this paper, the model of fixed abrasive diamond wire saw has been set up, and its cutting mechanism has been discussed. Then, the material removal rate model and wire saw cutting efficiency model have been established. the speed of wire saw, the number of the dynamic effective abrasive and the workpiece feed rate have been analyzed to study their impaction on the stability of cutting process. Finally, some rules and suggestions were brought forward.

Investigation on Strain Films in the Thin Film Resistance Strain Gauge

Strain films in the thin film resistance strain gauge are prepared by magnetron sputtering method. Some results concerning the electromechanical and structural properties of nichrome (Ni80Cr20 wt.%) thin films are presented. As compared to the well-known Ni-Cu (constantan) alloy film, which are widely used for manufacturing pressure and force sensors, nichrome (Ni80Cr20 wt.%) thin films exhibit gauge factor values of the same order of magnitude, but they are much more corrosion resistant and adherent to the substrate. The influences of composition and post-deposition annealing on the electrical resistance, temperature coefficient of resistance (TCR) and gauge factor of nichrome (Ni80Cr20 wt.%) thin films are discussed.

Mechanism of Brittle-Ductile Transition of Single Silicon Wafer at Different Temperatures

Formation, propagation and length of crack and hardness of single silicon wafer were investigated at different temperatures by means of Vickers indentation, using lower temperature testing unit with semiconductor refrigerating chip and higher temperature testing unit with closed electric furnace. The results show that the hardness of single silicon wafer decreases with the increase of temperature, while the length of crack increases with the increase of temperature. Ductile-brittle transition of the single silicon wafer can occur at different temperatures with the increase of load. When the load is smaller and temperature is lower, no cracks can be found.

Experimental Study on Cryogenic Polishing Single Silicon Wafer with Nano-Sized Cerium Dioxide Powders

Cryogenic polishing single silicon wafer with nano-sized CeO2 abrasives can be known as cryogenic fixed abrasives CMP (CFA-CMP). The abrasive slurry was made of nano-sized CeO2 particles dispersed in de-ionized water with a surfactant and the polishing slurry froze to form cryogenic polishing pad. Then the polishing tests of the blanket silicon wafers in the presence of the cryogenic polishing pad containing the nano-particulates were carried out. The morphologies and surfaces roughness of the polished silicon wafers were observed and examined on an atomic force microscope (AFM). The results show that a super smooth surface with roughness of 0. 293 nm is obtained within 5000 nm× 5000 nm and the removal of material is dominated by plastic flowage.