US 12,237,155 B2
Magnetic shielding for plasma sources
Hema Swaroop Mopidevi, Fremont, CA (US); Neil Martin Paul Benjamin, Palo Alto, CA (US); John Pease, San Mateo, CA (US); and Thomas Anderson, Hayward, CA (US)
Assigned to Lam Research Corporation, Fremont, CA (US)
Filed by Lam Research Corporation, Fremont, CA (US)
Filed on Oct. 20, 2021, as Appl. No. 17/506,538.
Application 17/506,538 is a division of application No. 16/045,635, filed on Jul. 25, 2018, granted, now 11,177,067.
Prior Publication US 2022/0044864 A1, Feb. 10, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H01J 37/32 (2006.01); H01F 27/36 (2006.01); H01L 21/683 (2006.01)
CPC H01J 37/32651 (2013.01) [H01F 27/36 (2013.01); H01F 27/366 (2020.08); H01J 37/321 (2013.01); H01J 37/32669 (2013.01); H01J 37/32091 (2013.01); H01J 37/32183 (2013.01); H01L 21/6831 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A magnetic shield for a plasma source, the magnetic shield comprising:
a cage comprising:
a first wall having a circular profile and at least partially defined by inner and outer radial regions, the first wall including:
a first inner plate disposed in the inner radial region of the first wall, the first inner plate including a ferro-magnetic material and extending outwards from a center of the first inner plate towards the outer radial region; and
an assembly of individual ferrite elements disposed in the outer radial region of the first wall, each individual ferrite element comprising a discrete, planar bar of uniform width and section and including a ferro-magnetic material, the assembly of individual ferrite elements including a first array of radially spaced bars confined to and extending axially in the outer radial region of the first wall, each radially spaced bar individually positioned in relation to the first inner plate of the first wall and joined at a radially inner end thereof to the first inner plate and extending radially outward therefrom, each radially spaced bar being joined to a periphery of the first inner plate at circumferentially spaced apart locations;
a second wall being disposed on an opposite side of the first wall, the second wall having a circular profile and at least partially defined by inner and outer radial regions, the second wall comprising:
a second inner plate disposed in the inner radial region of the second wall, the second inner plate extending outwards from a center of the second inner plate towards the outer radial region; and
an assembly of individual elements disposed in the outer radial region of the first wall, each individual element comprising a discrete, planar bar of uniform width and section, the assembly of individual elements including a second array of radially spaced bars confined to and extending axially in the outer radial region of the second wall, each radially spaced bar individually positioned in relation to the second inner plate of the second wall and joined at a radially inner end thereof to the second inner plate and extending radially outward therefrom, each radially spaced bar being joined to a periphery of the second inner plate at circumferentially spaced apart locations;
a third array of bars arranged such that one end of each of the third array of bars is attached to an outer radial end of a respective one of the first array of radially spaced bars in an orthogonal orientation relative thereto and another end of the each of the third array of bars is attached to an outer radial end of a respective one of the second array of radially spaced bars in an orthogonal orientation relative thereto, the second array being substantially parallel to the first array;
wherein the cage is sized and configured to enclose an RF source coil for the plasma source.