Method and apparatus for asymmetric processing of front side and back side of semiconductor substrates

An asymmetric double-sided substrate scrubber, comprising:

• a first roller having a first diameter;
• and
• a second roller having a second diameter, the first diameter configured to be greater than the second diameter,
• wherein the first roller is configured to be applied onto a first side of a substrate with a first force and the second roller is configured to be applied onto a second side of the substrate with a second force configured to be substantially equivalent to the first force such that the greater diameter of the first roller is configured to create a greater contact surface area with the first side of the substrate than the second roller with the second side of the substrate enabling the first roller to apply more mechanical action on the first side of the substrate.

An asymmetric double-sided substrate scrubber, comprising:

• a pair of first drums having a first belt-type brush mounted thereon, the first belt-type brush being constructed from a first material, the first belt-type brush having a first density;
• and
• a pair of second drums having a second belt-type brush mounted thereon, the second belt-type brush being constructed from a second material, the second belt-type brush having a second density configured to be greater than the first density,
• wherein the first belt-type brush is configured to be applied onto a first side of a substrate with a first force and the second belt-type brush is configured to be applied onto a second side of the substrate with a second force substantially equivalent to the first force.

A method for processing a front side and a back side of a wafer asymmetrically, the method comprising:

• configuring a first brush for processing the front side of the wafer to have a first compressibility;
• configuring a second brush for processing the back side of the wafer to have a second compressibility;
• and
• applying equal forces to the front side and the back side of the wafer using the first brush and the second brush such that the first brush achieves a greater compressibility on the front side of the wafer than the second brush on the back side of the wafer enabling the first brush to apply more mechanical action on the first side of the wafer.

A method for cleaning a front side and a back side of a wafer asymmetrically, the method comprising:

• providing a first roller having a material with a first compressibility;
• providing a second roller having a material with a second compressibility, the first compressibility configured to be greater than the second compressibility;
• inserting the wafer such that the first roller having the material with the greater compressibility is closer to the front side of the wafer and the second roller having the material with the lower compressibility is configured to be adjacent to the back side of the wafer;
• applying equal force to the front side and the back side of the wafer using the first roller and the second roller such that the greater compressibility of the first roller is configured to provide a larger surface area coverage than the second roller with the back side of the wafer, the larger surface area coverage of the first roller enabling the first roller to apply more mechanical action on the front side of the wafer;
• continuing a scrubbing of the wafer using the first roller and the second roller while applying fluids through one of the brush and a fluid application nozzle;
• and
• discontinuing the scrubbing when the cleaning process removes contaminants on the front side and the back side of the wafer.

An asymmetric double-sided substrate scrubber, comprising:

• a first roller constructed from a first material having a first density;
• and
• a second roller constructed from a second material having a second density, the second density configured to be greater than the first density,
• wherein the first roller is configured to be applied onto a first side of a substrate with a first force and the second roller is configured to be applied onto a second side of the substrate with a second force that is configured to be substantially equivalent to the first force, and further wherein the higher density of the second material causes the second roller to have a low compressibility and the lower density of the first material causes the first roller to have a higher compressibility, and a density of the first material is configured to be between approximately about 0.07 g/cm3 and 0.085 g/cm3.

An asymmetric double-sided substrate scrubber, comprising:

• a first roller constructed from a first material having a first density;
• and
• a second roller constructed from a second material having a second density, the second density configured to be greater than the first density,
• wherein the first roller is configured to be applied onto a first side of a substrate with a first force and the second roller is configured to be applied onto a second side of the substrate with a second force that is configured to be substantially equivalent to the first force, and further wherein the first side of the substrate is a back side of the substrate and the second side of the substrate is a front side of the substrate and a density of the second material is configured to be between approximately about 0.08 g/cm3 and 0.095 g/cm3.