PLASMA ETCHING APPARATUS
A plasma etching apparatus includes first, second and third chambers, and a plasma generation device. An inner cross-sectional area and shape of the second chamber interior substantially corresponds to the upper surface of a substrate, and a substrate support is disposed so that, in use, the substrate is substantially in register with the interior of the second chamber, and the upper surface of the substrate is positioned at a distance of 80 mm or less from the interface between the second and third chambers.
1 . A plasma etching apparatus for plasma etching a substrate, the apparatus including:
a first chamber having a plasma generation region, the plasma generation region having a cross-sectional area and shape;
a plasma generation device for generating a plasma in the plasma generation region;
a second chamber into which the plasma generated in the plasma generation chamber can flow, wherein the second chamber defines an interior having a cross-sectional area and shape, and the cross-sectional area of the interior is greater than the cross-sectional area of the plasma generation region;
a third chamber having a substrate support for supporting a substrate of the type having an upper surface to be plasma etched, wherein the third chamber has an interface with the second chamber so that the plasma, or one or more etchant species associated with the plasma, can flow from the second chamber to etch the substrate;
in which:
the inner cross-sectional area and shape of the second chamber interior substantially corresponds to the upper surface of the substrate; and
the substrate support is disposed so that, in use, the substrate is substantially in register with the interior of the second chamber, and the upper surface of the substrate is positioned at a distance of 80 mm or less from the interface.
2 . A plasma etching apparatus according to claim 1 in which the substrate to be etched and the interior of the second chamber each have at least one width, and the ratio of the width of the interior of the second chamber to the width of the substrate is in the range 1.15 to 0.85, preferably 1.1 to 0.9.
3 . A plasma etching apparatus according to claim 2 in which the ratio of the width of the interior of the second chamber to the width of the substrate is in the range 1.5 to 1.0, preferably 1.1 to 1.0.
4 . A plasma etching apparatus according claim 1 in which the substrate support is disposed so that, in use, the upper surface of the substrate is positioned at a distance of 60 mm or less from the interface.
5 . A plasma etching apparatus according to claim 1 in which the substrate support is disposed so that, in use, the upper surface of the substrate is positioned at a distance of 10 mm or more from the interface.
6 . A plasma etching apparatus according to claim 1 in which the ratio of the cross-sectional area of the plasma generation region to the cross-sectional area of the second chamber is in the range 0.07 to 0.7.
7 . A plasma etching apparatus according to claim 1 in which the first and second chambers are co-axial.
8 . A plasma etching apparatus according to claim 1 in which the first and second chambers are both of circular cross-section.
9 . A plasma etching apparatus according to claim 1 in which the first chamber is of a bell jar shape.
10 . A plasma etching apparatus according to claim 1 in which the interface is defined by a spacer element disposed between the second chamber and the third chamber.
11 . A plasma etching apparatus according to claim 1 further including a baffle disposed on or near to the substrate support in order to channel a gas flow in the vicinity of the substrate.
12 . A plasma etching apparatus according to claim 1 in which the substrate support is configured to support a substrate having a diameter of at least 200 mm.
13 . A plasma etching apparatus according to claim 1 in combination with the substrate, the substrate being supported by the substrate support.
14 . A kit for retrofitting an existing plasma etching apparatus in order to provide a retrofitted plasma etching apparatus according to claim 1 , the kit including:
an adapter for connection to one or more portions of the existing plasma etching apparatus, the adapter including a sleeve which is configured to act as the second chamber when the adapter is connected, and further including connection means permitting the adapter to be connected to said one or more portions of the existing plasma etching apparatus to locate the sleeve in place.
15 . A kit according to claim 14 in which the adapter further includes one or more flange portions for connection to one or more portions of the existing plasma etching apparatus.
16 . A kit according to claim 14 further including a spacer element configured to be disposed underneath the sleeve and connectable to the adapter and/or the existing plasma etching apparatus so as to define the interface between the second chamber and the third chamber in the retrofitted plasma etching apparatus.
17 . A method of plasma etching a substrate including the steps of:
i. providing a plasma etching apparatus according to claim 1 ;
ii. causing the substrate to be supported by the substrate support so that the substrate is substantially in register with the interior of the second chamber and the upper surface of the substrate is positioned at a distance of 80 mm or less from the interface;
iii. generating a plasma in the plasma generation region; and
iv. causing the plasma, or one or more etchant species associated with the plasma, to etch the substrate.