Specific Process Knowledge/Thin film deposition/Electroplating-Ni: Difference between revisions
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The maximum allowed thickness is ~1,4 mm (1400 µm), since a higher thickness will make the release of the sample difficult and likely damage the sample holder. This corresponds to a charge of 53-54 Ah on a four inch wafer. | The maximum allowed thickness is ~1,4 mm (1400 µm), since a higher thickness will make the release of the sample difficult and likely damage the sample holder. This corresponds to a charge of 53-54 Ah on a four inch wafer. | ||
The plating bath is an aqueous solution of nickel sulfamate, boric acid and sulfamic acid. The bath is moderately acidic (pH = 3, | The plating bath is an aqueous solution of nickel sulfamate, boric acid and sulfamic acid. The bath is moderately acidic (pH = 3,75). The pH is kept constant by an automatic pH measurement and sulfamic acid dosing module. The temperature of the bath is 52°C. The sample will spin at 60 RPM during deposition. | ||
Uniformity across a 4" wafer is around 5% for the standard processes (the edge being slightly thicker than the center of the sample). Running at high current densities will deposit a nickel layer that is quite soft. Decreasing current density will increase tensile strength of the deposited nickel. | Uniformity across a 4" wafer is around 5% for the standard processes (the edge being slightly thicker than the center of the sample). Running at high current densities will deposit a nickel layer that is quite soft. Decreasing current density will increase tensile strength of the deposited nickel. | ||