Patent ID: 9562291
Date: 2017-02-07
CPC Classifications: C23F,H01L

Claim:
1. An apparatus comprising: a fluid reservoir configured to receive a fluid including an etchant and a cassette configured to receive a plurality of wafers; a roller member in the fluid reservoir to frictionally engage the wafers when the cassette is in the fluid reservoir; and a motor situated outside the fluid reservoir and coupled to the roller member such that activation of the motor causes corresponding rotation of the roller member and rotation of the wafers when the roller member is in frictional engagement with the wafers; and a fluid agitator in fluid communication with the fluid reservoir to introduce bubbles into the fluid when the fluid is in the fluid reservoir, the fluid agitator further comprising a first fluid agitator region and a second fluid agitator region, the first and second fluid agitator regions defining a plurality of openings for forming bubbles of a predetermined size when a gas is passed therethrough, the first fluid agitator region being configured to introduce bubbles into the fluid at a first rate and the second fluid agitator region being configured to introduce bubbles into the fluid at a second rate, the second rate being higher than the first rate, the first fluid agitator region being located such that when the cassette is received in the fluid reservoir, bubbles introduced into the fluid from the first fluid agitator region will flow adjacent respective central regions of the wafers, and the second fluid agitator region being located such that when the cassette is received in the fluid reservoir, bubbles introduced into the fluid from the second fluid agitator region will flow adjacent respective edge portions of the wafers while the central regions of the wafers will remain substantially free of bubbles introduced into the fluid from the second fluid agitator region; wherein the wafers are displaced with respect to a bottom portion of the cassette when the cassette is in the fluid reservoir to promote fluid flow across the wafers.