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US 4,940,507 AGranted
Lapping means and method
AssigneeMotorola, Inc.
InventorJosephine Harbarger
Life of this patent
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AssigneeMotorola, Inc.
InventorJosephine Harbarger
Estimating the term…
An improved means and method for polishing or lapping thin wafers, especially semiconductor wafers, in a lapping plate is obtained by providing additional slurry holes in the lapping plate between the wafer receiving holes. In a first embodiment useful with wafers having a small initial taper, the additional slurry holes are radially oriented and have a length about equal to the wafer diameter so that, as the lapping plate rotates in the lap machine, the lapping slurry feeds through the holes to providing slurry uniformly to the underside of the wafers being lapped. In a second embodiment useful for wafers with a large initial taper, slurry holes of varying width and/or length are used to vary the amount of slurry reaching different parts of the wafers so that a predetermined variation in lapping occurs across the wafer to correct the taper. Yield is thereby improved.
A process for treating major faces of thin wafers, comprising:
A process for treating major faces of thin wafers, comprising:
An apparatus for lapping or polishing major faces of thin wafers, comprising a lapping plate of a pre-determined thickness and having multiple wafer holes extending therethrough adapted to receive the thin wafers with their major faces approximately parallel to major faces of the lapping plate, and having multiple slurry holes ahead of the wafer holes in the direction of rotation of the lapping plate and spaced apart from the wafer holes.
In an apparatus for treating major faces of thin wafers, the improvement comprising, a circular lapping plate having N evenly spaced circular wafer holes of substantially equal diameter tangential to spaced-apart first and second circumferences, and N slurry holes located between the N wafer holes and at least partly between the first and second circumferences.
Dependencies are inferred from the claim text.