Abstract: A vertically stacked planarization machine includes two or more vertically stacked individual platens on which wafers are polished. The wafers are held by wafer holders which may rotate the wafers. The individual platens are orbited in order to polish the wafers. Alternatively, the individual platens are rotated in order to polish the wafers. The platens may have a top and bottom polishing pad for polishing multiple wafers. A single wafer holder, using hydraulic or pneumatic means, between two platens will hold and exert pressure on both a downward wafer and an upward wafer. The pressure exerted onto the top and bottom wafers by the dual wafer holder is designed to be equal to prevent any bowing of the platen. Preferably, the platens are supported by three vertical members positioned at 120 degree intervals around the circumference of the platens to form a platen stack.

Abstract: A vertically stacked planarization machine includes two or more vertically stacked individual platens on which wafers are polished. The wafers are held by wafer holders which may rotate the wafers. The individual platens are also orbited in order to polish the wafers. The platens may have a top and bottom polishing pad for polishing multiple wafers. A single wafer holder, using hydraulic or pneumatic means, between two platens will hold and exert pressure on both a downward wafer and an upward wafer. The pressure exerted onto the top and bottom wafers by the dual wafer holder is designed to be equal to prevent any bowing of the platen. The platens are supported by three vertical members positioned at 120 degree intervals around the circumference of the platens to form a platen stack. Transport elevators are used to carry the wafers to and from the wafer holders and the platens.

Abstract: A vertically stacked planarization machine includes two or more vertically stacked individual platens on which wafers are polished. The wafers are held by wafer holders which may rotate the wafers. The individual platens are also orbited in order to polish the wafers. The platens may have a top and bottom polishing pad for polishing multiple wafers. A single wafer holder, using hydraulic or pneumatic means, between two platens will hold and exert pressure on both a downward wafer and an upward wafer. The pressure exerted onto the top and bottom wafers by the dual wafer holder is designed to be equal to prevent any bowing of the platen. The platens are supported by three vertical members positioned at 120 degree intervals around the circumference of the platens to form a platen stack. Transport elevators are used to carry the wafers to and from the wafer holders and the platens.

Abstract: A magnetoresistive bubble detector which includes an expander, a first and second detector element and a dummy element is disclosed. An expanded bubble is propagated from the first detector element to the second detector element. The detectors are coupled in pairs with the first element of one detector and the second element of the other detector connected in a bridge circuit with the dummy elements. Two independent streams of spaced-apart bubbles are detected within the bridge circuit.

Abstract: An error repairing method and apparatus for a magnetic bubble memory for restoring stored binary data to its original form are described. The method and apparatus are employed to compensate for random error in bubble memories resulting from slipped or disappeared bubbles. The data is coded with an error correcting code, such as a Hamming or Fire code, before storage. The stored, coded data is periodically read from memory and errors are detected and corrected. The corrected, coded data is rewritten into memory. In one embodiment the frequency of the repair cycles is a function of the rate at which errors are detected.