Sumco has been granted a patent for a double-sided polishing method for wafers. The method involves measuring the inclination value of carriers near the edge of the wafer loading hole, selecting carriers with inclination values below a threshold, and using them to polish the wafer. GlobalData’s report on Sumco gives a 360-degree view of the company including its patenting strategy. Buy the report here.
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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.
Double-sided polishing method for wafers using inclined carriers
A recently granted patent (Publication Number: US11772231B2) describes a double-sided polishing method for wafers. The method involves compressing and holding a wafer along with a carrier using upper and lower platens, while rotating them and supplying slurry to the wafer. The patent claims a specific process for selecting carriers based on the inclination value of their main surface near the edge of the wafer loading hole.
The method begins by measuring the inclination value of the main surface of each carrier near the edge of the wafer loading hole. From these measurements, one or more carriers are selected based on their inclination value being equal to or smaller than a predetermined threshold. The selected carriers are then used to perform the double-sided polishing on the wafer.
The patent specifies that the threshold for the inclination value is set to 0.25×10-3. Additionally, the measurement range for the inclination value is defined as the area between the inner peripheral edge of the wafer loading hole and a position 2 mm inward from it. The inclination value can be determined at one position or as the mean value of multiple positions along the inner peripheral edge of the wafer loading hole.
The patent also mentions that the carriers used in the method are composed of a metal carrier body with a circular opening and a ring-shaped resin inserter along the inner periphery of the opening. The width of the resin inserter is specified to be equal to or larger than 2 mm.
Furthermore, the method allows for the use of multiple carriers to simultaneously polish multiple wafers. In this case, the inclination values of the main surfaces of all the carriers near the edge of the wafer loading hole must be equal to or smaller than the threshold, and the variation in thickness among the carriers should fall within ±4 µm.
Overall, this granted patent presents a specific double-sided polishing method for wafers that involves selecting carriers based on their inclination values near the edge of the wafer loading hole. The method aims to improve the polishing process and ensure consistent results.
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GlobalData Patent Analytics tracks bibliographic data, legal events data, point in time patent ownerships, and backward and forward citations from global patenting offices. Textual analysis and official patent classifications are used to group patents into key thematic areas and link them to specific companies across the world’s largest industries.
