Substrate processing system and method

#This invention relates to a substrate processing system and method, and more particularly, to a processing system and method for performing clean processing of semiconductor wafers.

#As the dimensions of LSIs continue to shrink, the technology for cleaning semiconductor wafers has become more and more important. Important things in cleaning steps of semiconductor wafers include removing impurities such as particles or heavy materials that are generated in the preceding steps, removing chemicals that are used in the cleaning steps, and suppressing the generation of defects such as particles or watermarks in the cleaning steps. Generally, the cleaning of semiconductor wafers is wet cleaning, where the cleaning is performed using chemicals such as acid, alkaline, or organic solvent.

#Typical clean processing comprises a first step of removing particles, or the like, from a silicon wafer, a second step of removing unwanted native oxides on the silicon surface, and a third step of removing heavy metals, or the like, attached to the silicon wafer, and, in each step, desired chemical cleaning is performed. In the first step, an alkaline mixture solution (hereinafter called SC-1) consisting of aqueous ammonia, hydrogen peroxide solution, and ultrapure water is used. In the second step, hydrofluoric acid diluted with ultrapure water (hereinafter called DHF (dilute hydrofluoric acid)) is used. In the third step, an acid mixture solution (hereinafter called SC-2) consisting of hydrochloric acid, hydrogen peroxide solution, and ultrapure water is used. In addition, between each of the steps, a rinse processing is performed. Finally, a complete dry is performed in a drying unit.

#For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:

#FIG. 1 is a schematic block diagram showing a semiconductor wafer clean processing system according to an embodiment of the present invention;

#FIGS. 2(a) through 2(d) show film-forming steps of a wiring layer using a semiconductor wafer clean processing system according to an embodiment of the present invention;

#FIG. 1 is a block diagram showing the concept of a semiconductor wafer clean processing system according to an embodiment of the present invention. In FIG. 1, the clean processing system comprises a small-sized housing 100, which provides a substantially sealed space, wherein the housing 100 comprises a first process chamber 110, a second process chamber 120, and a drying unit 130. The first and the second process chambers 110 and 120, and the drying unit 130 are arranged vertically in a multi-stage configuration, and the transfers of a semiconductor wafer between these chambers and the unit are performed by a first transfer robot 140. A wafer cassette 160 stores the semiconductor wafers to be cleaned or the cleaned semiconductor wafers, and inside of the wafer cassette 160 has a configuration so that it can be purged with nitrogen gas. The wafer transfer from the wafer cassette 160 to the first process chamber 110 and the wafer transfer from the drying unit 130 to the wafer cassette 160 are performed by a second transfer robot 150. In the upper portion of the housing 100, gas-feeding inlets 170 are provided for feeding nitrogen gas into the housing.

#The first process chamber 110 is a chamber for performing an SC-1 clean to remove particles, or the like, from the semiconductor wafer, and the second process chamber 120 is a chamber for performing a cleaning with DHF to remove unwanted native oxides from the semiconductor wafer surface. The inside of both the first and second process chambers 110 and 120 is kept under a nitrogen gas atmosphere. The drying unit 130 is a unit for finally drying the semiconductor wafer, which is cleaned in the second process chamber 120, and typically comprises a vacuum heat apparatus. The first and the second transfer robots 140 and 150 have functions to hold the semiconductor wafer contactlessly and control the semiconductor wafer in an inert gas atmosphere, as described later.

#The semiconductor wafer, which is stored in the wafer cassette 160, is transferred one by one to the first process chamber 110 by the second transfer robot 150. The semiconductor wafer is cleaned in the first process chamber 110 to remove the unwanted materials which are generated in the preceding etching process. The semiconductor wafer is then transferred contactlessly and controlled under a nitrogen atmosphere by the first transfer robot 140 to the second process chamber 120, where unwanted native oxides are removed by using DHF. Then the wafer is transferred contactlessly and controlled under a nitrogen atmosphere by the first transfer robot 140 to the drying unit 130, where the wafer is dried. The dried semiconductor wafer is transferred contactlessly and controlled under a nitrogen atmosphere by the second transfer robot 150 to the wafer cassette 160. After a predetermined number of wafers are stored in the wafer cassette 160, the inside of the wafer cassette 160 is purged with nitrogen gas.