A method of processing substrates in a lithography system unit of a lithography system, the lithography system unit comprising at least two substrate preparation units for preparing substrates, said preparing including clamping a substrate onto a substrate support structure, a load lock unit comprising a chamber with at least first and second substrate positions, and a substrate handling robot for transferring substrates clamped onto substrate support structures between the substrate preparation units and the load lock unit, and for transferring unclamped substrates towards and from the substrate preparation units, wherein the method comprises: providing a sequence of substrates to be exposed to the robot, including an Nth substrate, an N-lth substrate immediately preceding the Nth substrate, and an N+1th substrate immediately following the Nth substrate, wherein the N-lth substrate is a substrate that is processed prior to the Nth substrate and wherein the N+1th substrate is a substrate that is processed after the Nth substrate; transferring the Nth substrate by means of the robot to a first one of the substrate preparation units; clamping the Nth substrate on a first substrate support structure in the first substrate preparation unit, the Nth substrate and first substrate support structure together forming a clamped Nth substrate; transferring the clamped Nth substrate by means of the robot from the first substrate preparation unit to an unoccupied one of the first and second positions in the chamber of the load lock unit for exposure in the lithography system unit, before exposure of the N-lth substrate in the lithography system unit is completed; and exposing the clamped Nth substrate in the lithography system unit, wherein the load lock unit comprises a load lock robot and the method further comprises pumping down the load lock unit after transfer of the clamped Nth substrate to the load lock unit; transferring the exposed clamped N-1th substrate, by means of the load lock robot arm, from the lithography system unit to an unoccupied one of the first and second positions of the pumped down load lock unit; transferring the clamped Nth substrate, by means of the load lock robot, from the pumped down load lock into the lithography system unit; and venting the load lock unit prior to transferring the exposed clamped N-1th substrate to the first substrate preparation unit providing a sequence of substrates to be exposed to the robot, including an Nth substrate, an N-lth substrate immediately preceding the Nth substrate, and an N+1th substrate immediately following the Nth substrate, wherein the N-lth substrate is a substrate that is processed prior to the Nth substrate and wherein the N+1th substrate is a substrate that is processed after the Nth substrate; transferring the Nth substrate by means of the robot to a first one of the substrate preparation units; clamping the Nth substrate on a first substrate support structure in the first substrate preparation unit, the Nth substrate and first substrate support structure together forming a clamped Nth substrate; transferring the clamped Nth substrate by means of the robot from the first substrate preparation unit to an unoccupied one of the first and second positions in the chamber of the load lock unit for exposure in the lithography system unit, before exposure of the N-lth substrate in the lithography system unit is completed; and exposing the clamped Nth substrate in the lithography system unit, wherein the load lock unit comprises a load lock robot and the method further comprises pumping down the load lock unit after transfer of the clamped Nth substrate to the load lock unit; transferring the exposed clamped N-1th substrate, by means of the load lock robot arm, from the lithography system unit to an unoccupied one of the first and second positions of the pumped down load lock unit; transferring the clamped Nth substrate, by means of the load lock robot, from the pumped down load lock into the lithography system unit; and venting the load lock unit prior to transferring the exposed clamped N-1th substrate to the first substrate preparation unit