NOVELTY - A semiconductor structure (11) is exposed to a vaporized cleaning agent (99V), so that the cleaning agent penetrates into the openings of a structure. The semiconductor structure is then subjected to pressure and temperature, so that the cleaning agent is condensed to a liquid phase.    USE - For cleaning semiconductor structure having complex geometries such as high-aspect ratio openings, in semiconductor device fabrication.    ADVANTAGE - The semiconductor structure can be effectively and economically cleaned using vapor phase condensation. As the cleaning is performed at an atmospheric pressure, the throughput is increased and the cleaning cost is reduced.    DETAILED DESCRIPTION - A thermal gradient cleaning chamber (120) including three regions (121-123), is provided. Heat is supplied to the bottom region (121) using heaters (28) to vaporize the cleaning agent. The middle region (122) contains the cleaning agent in vapor phase. The top region (123) is cooled by cooling structures (29) to condense the cleaning agent. The semiconductor structure is located in the middle region and is then moved to the top region where the cleaning agent condenses to the liquid phase. The processes are repeated until the structure attains a predetermined cleanliness level. The structure is placed in a vacuum chamber for removing the residual cleaning agent from the semiconductor structure. The structure is placed in a variable pressure cleaning chamber that includes vaporized hydrocarbon. The pressure of the cleaning chamber is in the range of 0-6000 torr. A pressure-tight piston of the cleaning chamber is lowered and raised so that the hydrocarbon condenses to the liquid phase and then vaporizes. The processes is repeated until a predetermined cleanliness is attained.    DESCRIPTION OF DRAWING(S) - The figure shows the sequential views of the semiconductor structure cleaning process.    Semiconductor structure (11)    Heaters (28)    Cooling structure (29)    Vaporized cleaning agent (99V)    Thermal gradient cleaning chamber (120)    Regions (121-123)