Patent ID: 7235141

Claim:
A lift-off method for wafers each having a surface on which is a pattern containing a pattern portion to be removed; the method comprising steps of: deploying the wafers, immersed in a tank full of chemical liquid, side-by-side in a generally horizontal first row with each wafer at an angle at which said surface faces downward and is slanted at an angle with respect to the downward direction; providing a first spewing port; providing a second spewing port; deploying a second row of wafers arranged similarly to the first row of wafers, wherein the first row of wafers and the first spewing port are placed symmetrically relative to the second row of wafers and the second spewing port, whereby the first row of wafers and the second row of wafers form a V-shape; spewing the chemical liquid from outside the tank through the spewing ports onto an upper portion of the downward-facing surface of each wafer containing the pattern portion to be removed, thereby producing a flow of the chemical liquid in a specified downward-slanted direction along the surface of the wafer; providing a sucking port adjacent to a lower portion of the downward-facing wafer surfaces, said sucking port being at a lower elevation than the spewing ports; collecting the spewed chemical liquid at said sucking port; and conveying the chemical liquid to the outside of the tank from said sucking port.