Method of clamping a substrate and clamp preparation unit using capillary clamping force

A clamp preparation unit for preparing an arrangement of a substrate clamped on a surface of a substrate support structure, the unit comprising:

• the substrate support structure, the surface of which is provided with a plurality of contact elements;
• a liquid dispensing unit for applying a liquid from above on to the surface of the substrate support structure, so that the liquid forms a layer having a layer thickness greater than a height of the contact elements so that the contact elements are covered by the liquid layer;
• a substrate transfer unit for placing the substrate onto the liquid layer, such that the substrate is not completely immersed in the liquid,
• a liquid removal system for removing an excess portion of the liquid from under the substrate, thereby lowering the substrate towards the surface of the substrate support structure so that the substrate rests on the plurality of contact elements and is not completely immersed in the liquid, such that the substrate is clamped by means of a capillary clamping force exerted by a capillary layer of the liquid between the substrate and the surface of the substrate support structure, the capillary layer having an outer liquid surface defining a first contact angle between the capillary layer and the substrate and a second contact angle between the capillary layer and the substrate support structure, wherein the liquid removal system comprises a gas distribution system for providing a gas flow along a circumference of the outer liquid surface.

A method of preparing an arrangement of a substrate clamped on a surface of a substrate support structure, the method comprising:

• applying a liquid on the surface of the substrate support structure, the surface being provided with a plurality of contact elements, so that the liquid forms a layer covering the contact elements;
• placing the substrate on top of the liquid layer such that the substrate is not completely immersed in the liquid,
• wherein the substrate is placed on top of the liquid layer by placing the substrate such that an edge at a first end portion of the substrate contacts the liquid layer at an initial angle to the top surface of the liquid layer so that the bottom surface of the substrate and the top surface of the liquid layer are not parallel, and subsequently lowering a portion of the substrate not initially contacting the liquid layer by decreasing the angle until the substrate fully rests on top of the liquid layer, and
• subsequently lowering the substrate towards the surface of the substrate support structure by removing an excess portion of the liquid from underneath the substrate, so that the substrate rests on the plurality of contact elements and is not completely immersed in the liquid, such that the substrate is clamped by a capillary clamping force exerted by a capillary layer of the liquid between the substrate and the surface of the substrate support structure, the capillary layer having an outer liquid surface defining a first contact angle between the capillary layer and the substrate and a second contact angle between the capillary layer and the substrate support structure.

A clamp preparation unit for preparing an arrangement of a substrate clamped on a surface of a substrate support structure, the unit comprising:

• the substrate support structure, the surface of which is provided with a plurality of contact elements;
• a liquid dispensing unit for applying a liquid on to the surface of the substrate support structure so that the contact elements are covered by a liquid layer;
• a substrate transfer unit for placing the substrate onto the liquid layer;
• and
• a liquid removal system for removing an excess portion of the liquid from under the substrate, thereby lowering the substrate towards the surface of the substrate support structure until the substrate rests on the plurality of contact elements and is not completely immersed in the liquid, such that the substrate is clamped by means of a capillary clamping force exerted by a capillary layer of the liquid between the substrate and the surface of the substrate support structure, the capillary layer having an outer liquid surface defining a first contact angle between the capillary layer and the substrate and a second contact angle between the capillary layer and the substrate support structure;
• wherein the substrate transfer unit is adapted for placing the substrate on top of the liquid layer by placing the substrate such that an edge at a first end portion of the substrate contacts the liquid layer at an initial angle to the top surface of the liquid layer so that the bottom surface of the substrate and the top surface of the liquid layer are not parallel, and subsequently lowering a portion of the substrate not initially contacting the liquid layer by decreasing the angle with respect to the top surface of the liquid layer until the substrate fully rests on top of the liquid layer such that the substrate is not completely immersed in the liquid.