Measurement apparatus and method
A method and apparatus for extracting the contents ( 39 ) of voids ( 13 ) and/or pores present in a semiconductor device to obtain information indicative of the nature of the voids and/or pores, e.g. to assist with metrology measurements. The method includes heating the semiconductor wafer to expel the contents of the voids and/or pores, collecting the expelled material ( 41 ) in a collector, and measuring a consequential change in mass of the semiconductor wafer ( 29 ) and/or the collector ( 37 ), to extract information indicative of the nature of the voids. This information may include information relating to the distribution of the voids and/or pores, and/or the sizes of the voids and/or pores, and/or the chemical contents of the voids and/or pores. The collector may include a condenser having a temperature-controlled surface (e.g. in thermal communication with a refrigeration unit) for condensing the expelled material.
1. A semiconductor wafer metrology apparatus comprising:
a heating portion for heating a semiconductor wafer to expel material contained in voids formed in or beneath a layer deposited on the semiconductor wafer;
a collector for collecting the expelled material, the collector being partitioned into a plurality of separate collecting portions; and
a mass measurement unit for measuring the consequential change in mass of the semiconductor wafer and/or the collector.
2. Apparatus according to claim 1 , wherein the heating portion comprises a heat source in thermal contact with a surface of the semiconductor wafer opposite to a surface on which the layer is deposited.
3. Apparatus according to claim 1 , wherein the collector is a condenser having a temperature-controlled surface for condensing the expelled material.
4. Apparatus according to claim 3 comprising a refrigeration unit in thermal communication with the condenser to control the temperature of the surface for condensing the expelled material.
5. Apparatus according to claim 1 , wherein the surface of the collector facing the semiconductor wafer is partitioned into a uniform grid pattern of collecting portions by raised ribs on the surface.