Method for reducing metal contamination of silicon wafers during semiconductor manufacturing
AssigneeSiemens Aktiengesellschaft
InventorPeter Schulz
Life of this patent
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Abstract
A complex building agent, such as EDTA is added in a predetermined concentration to the "SC 1" step of a "PIRANHA-RCA" cleaning sequence for reducing the metal contamination left on the surface of a silicon wafer after completion of this cleaning step.
Claims8
A method for reducing the metal contamination on the surface of a silicon wafer during an "RCA-clean" cleaning sequence performed on said silicon wafer in fabricating semiconductor devices therefrom, said method comprising the improvement steps of:
- adding a said concentration ranging from 0.05 mg/l to 0.10 mg/l of a complex building agent EDTA to a chemical solution selected from the group consisting of (NH.sub.4 OH+H.sub.2 O.sub.2 +O.sub.3) or (NH.sub.4 OH+H.sub.2 O.sub.2 +H.sub.2 O) provided for use in an "SC 1" cleaning step of said "RCA-clean", to provide a modified "SC 1" cleaning solution for keeping metal complexes bound in solution to substantially prevent the metals from being retained on the surface of said silicon wafer said concentration of EDTA being dependent upon the concentrations of ammonium hydroxide and ozone;
- retaining said modified "SC 1" cleaning solution in a tank tool;
- and
- submerging said silicon wafer in said modified "SC 1" cleaning solution in said tank tool, for a predetermined period of time to form a chemical complex with metal contaminates on the surface of silicon wafers during an "SC 1" step of said improved "RCA-clean".
A modified cleaning solution for improving the "SC 1" cleaning step of an "RCA-clean" sequence for silicon wafers by keeping metal complexes bound in solution during "SCI" cleaning of silicon wafers to substantially reduce metal contamination of surfaces of silicon wafers, comprising:
- a predetermined concentration of a complex building agent selected from the group consisting of EDTA and a chemical solution (NH.sub.4 OH+H.sub.2 O.sub.2 +O.sub.3) or (NH.sub.4 OH+H.sub.2 O.sub.2 +H.sub.2 O)(formula for the "SC 1" step.
The modified "SC 1" cleaning solution of claim wherein said complex building agent consists of EDTA having a concentration ranging from 0.05 mg/l to 0.10 mg/l, for concentrations of NH.sub.4 OH ranging for 0.004% by weight to 4% by weight, respectively, and of O.sub.3 ranging from 0.003% by weight to 5% by weight, respectively.
Dependencies are inferred from the claim text.