Sumco has filed a patent for a method of producing epitaxial silicon wafers. The method involves irradiating the surface of a silicon wafer with a cluster ion beam containing SiHx ions and C2Hy ions to form a modified layer in the surface portion of the wafer. A silicon epitaxial layer is then formed on this modified layer. The patent claims that a dose of at least 1.5×1014 ions/cm2 of SiHx ions is required. GlobalData’s report on Sumco gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData’s company profile on Sumco, 3D memory devices was a key innovation area identified from patents. Sumco's grant share as of September 2023 was 38%. Grant share is based on the ratio of number of grants to total number of patents.
Method of producing epitaxial silicon wafer using cluster ion beam
A recently filed patent (Publication Number: US20230317761A1) describes a method for producing an epitaxial silicon wafer. The method involves irradiating the surface of a silicon wafer with a cluster ion beam containing SiHx ions and C2Hy ions to create a modified layer in the surface of the wafer. This modified layer contains a solid solution of the constituent elements of the ion beam. The dose of SiHx ions used in the irradiation process is 1.5×1014 ions/cm2 or more.
After the modified layer is formed, a silicon epitaxial layer is grown on top of it. The patent specifies that the dose of C2Hy ions used in the irradiation process should be 1.0×1014 ions/cm2 or less. The source gas for the cluster ion beam is diethylsilane.
The patent also describes the resulting epitaxial silicon wafer. It consists of a silicon wafer with a modified layer in the surface portion. This modified layer contains a solid solution of carbon and/or hydrogen. In a defect analysis using a cross-sectional TEM image, a defect region with EOR defects is observed at a density of 5.0×107/cm2 or more. The amount of carbon distributed in the silicon epitaxial layer and the modified layer is 2.0×1014 atoms/cm2 or less. Additionally, a hydrogen concentration profile in the modified layer, determined by SIMS, shows a peak concentration of 1.0×1016 atoms/cm3 or more in the depth direction.
The patent also mentions the use of the epitaxial silicon wafer in the production of semiconductor devices. The method for producing a semiconductor device involves the steps described in the method for producing the epitaxial silicon wafer, as well as the formation of the semiconductor device in the silicon epitaxial layer of the wafer.
In summary, this patent describes a method for producing an epitaxial silicon wafer using a cluster ion beam and specifies the conditions for irradiation and growth of the epitaxial layer. It also provides details about the resulting wafer, including the presence of defects and the distribution of carbon and hydrogen. The patent further mentions the use of the epitaxial silicon wafer in the production of semiconductor devices.