Method for cleaning a glass substrate, method for fabricating a glass substrate, and magnetic disk using same
A method for cleaning a glass substrate which ensures removal of abrasive and other foreign matter without making a cleaning step complicated involves cleaning the glass substrate by scrubbing using two or more types of cleaning liquid having different Si element elution abilities. The cleaning liquid having the highest Si element elution is used first, and the cleaning liquid having the lowest Si element elution is used last.
1. A method for fabricating a glass substrate comprising:
polishing a glass substrate with an abrasive;
cleaning the polished glass substrate to remove at least a portion of the abrasive adhered to the glass substrate;
wherein cleaning the polished glass substrate comprises:
providing a first type of cleaning liquid having a Si element eluation in the range of 1 to 10,000 ppb/mm 2 , and being capable of eluting Si element from the glass substrate;
providing a non-liquid physical scrubbing element;
applying the first type of cleaning liquid to the glass substrate and to the non-liquid physical scrubbing element;
frictionally scrubbing the glass substrate with the non-liquid physical scrubbing element using the first type of cleaning liquid;
providing a second type of cleaning liquid having a Si element eluation in the range of 0.001 to 10 ppb/mm 2 , and being capable of eluting Si element from the glass substrate, wherein the first type of cleaning liquid has a higher Si element elution than the second type of cleaning liquid, and the first and second types of cleaning liquids contain substantially a same cleaning liquid ingredient but in different concentrations and are used in order of decreasing order concentration;
applying the second type of cleaning liquid to the glass substrate and to the same non-liquid physical scrubbing element; and
frictionally scrubbing the glass substrate with the non-liquid physical scrubbing element using the second type of cleaning liquid, wherein the frictionally scrubbing using the first type of cleaning liquid followed by the frictionally scrubbing using the second type of cleaning liquid is performed on a continuous basis using a single cleaning machine so that there is no interruption in the scrubbing process.
2. The method according to claim 1 , wherein the non-liquid physical scrubbing element is a brush, pad, or sponge roller.
3. The method according to claim 1 , wherein the cleaning liquid is hydrofluoric acid.
4. The method according to claim 1 , wherein among the first and second types of cleaning liquids, one used first has a lower specific resistance than one used last.