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, the substrate and the interior of the second chamber each having at least one width, characterised in that 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 1.0; 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 80mm or less from the interface. 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, the substrate and the interior of the second chamber each having at least one width, characterised in that 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 1.0; 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 80mm or less from the interface. the inner cross-sectional area and shape of the second chamber interior substantially corresponds to the upper surface of the substrate, the substrate and the interior of the second chamber each having at least one width, characterised in that 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 1.0; 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 80mm or less from the interface.