1. Field of the Invention
The present invention relates to a semiconductor workpiece cleaning method and apparatus and, more particularly, to a semiconductor workpiece cleaning method and apparatus to be adopted by or installed in a semiconductor wafer processing line to clean a semiconductor workpiece.
2. Background of the Invention
A semiconductor workpiece cleaning process in a semiconductor device fabricating process has increased in importance as semiconductor devices include finer structures and features. Recently, a single-tank cleaning apparatus which carries out a plurality of chemical cleaning processes in one tank has often been used to reduce floor space (i.e., footprint) necessary for installing the cleaning apparatus.
Wet semiconductor workpiece cleaning apparatuses are classified roughly into immersion cleaning apparatuses which immerse a workpiece in a chemical liquid for cleaning, and spray cleaning apparatuses which spray a chemical liquid onto the workpiece for cleaning.
A conventional single-tank dip type cleaning apparatus will be described with reference to FIG. 7. In this conventional cleaning apparatus, a workpiece 2 is held fixedly on guide members 3 in a chamber 1 defined by a vessel, and a cleaning chemical liquid or pure water is supplied into the chamber 1 through a lower part of the vessel, and discharged from the chamber 1 through an upper part of the vessel to clean the workpiece 2. Hot pure water and cold pure water are mixed in a line 4a so as to supply pure water of a predetermined temperature at a predetermined flow rate into the chamber 1. The chemical liquid is supplied from a chemical liquid supply unit 4b to the line 4a, so that the chemical liquid can be supplied into the chamber 1 simultaneously with the pure mixed water.
In this cleaning apparatus, pure water contained in the chamber 1 needs to be replaced with the chemical liquid so as to immerse the workpiece 2 in the chemical liquid. Subsequently, the chemical liquid contained in the chamber 1 needs to be replaced with pure water for water-rinsing after the workpiece 2 has been immersed in the chemical liquid. The process of replacing pure water with the chemical liquid and the process of replacing the chemical liquid with pure water lengthening processes. In particular, the water-rinsing process performed after the immersion of the workpiece in the chemical liquid takes considerable time to restore the resistivity of the rinsing water, which, in turn, reduces processing efficiency (i.e., throughput) of the cleaning process.
A conventional single-tank spray type cleaning apparatus will be described with reference to FIG. 8. In this single-tank spray type cleaning apparatus, a workpiece 2 is held by guide members 3 while turned, and a nozzle 4 sprays a cleaning liquid 5 on the workpiece 2 for cleaning. This single-tank spray type cleaning apparatus, as compared with the single-tank dip type cleaning apparatus, can easily be changed from a chemical cleaning process to a water rinsing process, and hence the throughput of the single-tank spray type cleaning apparatus is higher than that of the single-tank dip type cleaning apparatus. However, when the workpiece is rotated to spin-dry the workpiece after the last rinsing process, water marks, i.e., stains, are formed on the surfaces of the workpiece. Water marks formed on the workpiece adversely affect the characteristics of a device fabricated by processing the workpiece, and reduce the yield of the device production system remarkably. Thus, as determined by the present inventors, formation of water marks on the workpiece is a problem in the spray type cleaning apparatus.
There are no single-tank cleaning apparatuses provided with both a single tank in which a plurality of chemical liquids are used for cleaning, and capable of cleaning workpieces at a high throughput and without forming water marks thereon.
As mentioned above, the conventional semiconductor workpiece cleaning apparatuses require much time for cleaning, are inefficient, and form water marks on the workpieces during drying after cleaning.