Aug 2, 2010 at 05:00 o\clock
Jul 30, 2010 at 08:40 o\clock
Young's modulus of a silicon wafer
The expression that “higher in rigidity than a silicon wafer” means that it is less likely to be deformed by shearing force as compared with the silicon wafer. In other words, Young's modulus of the Monocrystalline wafer after reinforcement by a reinforcement member is higher than that of the silicon wafer before reinforcement (100 GPa or more but lower than 120 GPa).
Young's modulus of a silicon wafer after reinforcement is preferably from 120 to 1000 GPa. Where Young's modulus is less than 120 GPa, there is found no great difference in the amount of deflection as compared with silicon wafers which are not subjected to the treatment of the present invention. Further, where Young's modulus is in excess of 1000 GPa, the amount of deflection will hardly vary. Young's modulus of the silicon wafer after reinforcement is preferably from 120 to 500 GPa. Where Young's modulus is within the above range, the wafer carrying and wafer production processes under the same conditions as those of conventional wafers can be applied.
“A material different from silicon” may include silicon carbide (SiC), silicon oxide (SiOx), silicon nitride (SiNx) and poly silicon (poly Si).
The reinforcement member is preferably a material which is higher in rigidity than the silicon wafer in terms of comparison of Young's modulus by using a same-sized specimen of the silicon wafer and that of a material. However, such a material may be acceptable that is equal to or lower than the silicon wafer in rigidity.
The reinforcement member may be installed all over the back face of the silicon wafer so as not to be separated or may be installed only partially on the back face of the silicon wafer so as not to be separated. Where the reinforcement member is installed partially on the back face of the wafer, it is preferable that the reinforcement member is laid across the both ends of the back face of the silicon wafer manufacturer because the silicon wafer is increased in rigidity as compared with a case where it is not laid across as described above.
source:news chinasun-solar
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Silicon wafers are widely used
Generally, to fabricate various silicon devices, there has been widely used CZ silicon wafers which is manufactured by pulling up a silicon single crystal ingot from a silicon melt within a quartz crucible by a CZ method.In such a CZ wafer, excessive oxygen atoms eluted from the quartz crucible are interstitially caught in the silicon single crystal ingot, and the higher concentration of such interstitial oxygen atoms leads to, for example, oxygen precipitation from the silicon wafer, deterioration of a gate oxide film in a semiconductor integrated circuit, and an increase of a p-n junction leakage current. As such, upon forming semiconductor integrated circuits on the principal plane of the CZ wafer, there are reduced oxygen precipitations near the surface of the wafer by lowering the oxygen concentration of the silicon wafer supplier .
To this end, in the first aspect of the present invention, a silicon wafer is free of vacancy agglomerates and interstitial agglomerates, wherein the silicon wafer has a defect density of an oxide film of 0.1 piece/cm 2 or less, when the oxide film having a thickness of 5 to 25 nm is formed on the surface of the wafer and a DC voltage of 10 MV/cm is applied via the oxide film for 100 seconds, and wherein the silicon wafer manufacturer has an in-plane dispersion of 20% or less of a p-n junction leakage current in a p-n junction area of 1 mm 2 or more of a p-n junction portion when the p-n junction portions are formed on the surface of the wafer.
source:news chinasun-solar
