US 5,718,615 AGranted

Semiconductor wafer dicing method

OwnerJohn N. Boucher, David E. Bajuneinventors

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Abstract

A semiconductor wafer dicing saw is controlled by monitoring blade exposure from a flange holding the blade during the wafer dicing process. As the wafer is cut and separated into discrete electronic chips, the dicing blade wears. As the blade is brought closer and closer toward the wafer during cutting, the blade exposure is continuously being reduced. The small dimensions, coolant flow, and close tolerances typical in the wafer dicing process, do not permit visual inspection. Excess blade wear and thus reduced exposure or flange clearance between the blade cutting edge and flange edge will cause damage to the wafer and blade by restricting coolant flow or by contact of the flange with the wafer. A system is provided for automatically measuring the flange clearance using a height sensor to determine blade wear and a processor for monitoring blade movement toward the wafer during the wafer dicing and stopping the movement when the blade cutting edge reaches a minimum separation distance from the work surface or a minimum blade exposure is reached. A blade history is stored that provide a number of cuts make through the wafer for a given wear.

Claims26

Dependent claims

A method for automatically dicing a semiconductor wafer using a dicing saw having a spindle for carrying a dicing blade and a work surface for holding the semiconductor wafer, the spindle supporting the dicing blade and a flange pair for rotation of the dicing blade about a spindle axis and movement of the dicing blade for cutting the semiconductor wafer, the method useful in providing a safe flange clearance between a flange pair edge and the semiconductor wafer, the method comprising the steps of:

providing a flange pair having a fixed outer diameter for providing an initial exposed portion for the dicing blade carried therebetween;
mounting a dicing blade between a flange pair onto the dicing saw spindle for rotation of the dicing blade, the dicing blade having an outer diameter defining a cutting edge, the dicing blade having an outer diameter that is greater than a flange pair diameter for providing a blade exposed portion extending radially outward from the flange edge for cutting into a semiconductor wafer;
placing a semiconductor wafer onto the work surface of the dicing saw for holding the wafer onto the surface during dicing of the semiconductor wafer;
operating the dicing saw for cutting the semiconductor wafer;
positioning the dicing saw spindle at a first spindle axis position above the work surface;
dicing the semiconductor wafer by making a first cut to a preselected depth into the semiconductor wafer, the dicing blade wearing with each cut thus reducing the blade exposed portion, each dicing step reducing the flange clearance between the flange pair edge and the semiconductor wafer for each subsequent dicing step and cut to the preselected depth;
moving the spindle to a second spindle axis position for moving the dicing blade closer to the work surface for making a subsequent cut into the semiconductor wafer to the preselected depth;
repeating the spindle moving and dicing steps for making subsequent cuts into the semiconductor wafer to the preselected depth;
measuring the dicing blade diameter after a preselected number of cuts;
and
calculating the flange clearance after the preselected number of cuts for automatically monitoring a remaining amount of blade exposed portion and thus the flange clearance for the wafer dicing steps.

8 more elements

A method for automatically dicing a semiconductor wafer using a dicing saw having a spindle for carrying a dicing blade and a work surface for holding the semiconductor wafer thereon, the spindle supporting the dicing blade and a flange pair for rotation about a spindle axis and movement of the dicing blade for cutting the semiconductor wafer, the method useful in providing a safe flange clearance between a flange pair edge and the semiconductor wafer top surface, the method comprising the steps of:

providing a flange pair having a fixed outer diameter for providing an initial exposed portion for the dicing blade carried therebetween;
mounting a dicing blade between a flange pair onto the dicing saw spindle for rotation of the dicing blade about the spindle axis, the dicing blade having an outer diameter defining a cutting edge, the dicing blade having a diameter which is greater than the flange pair diameter for providing a blade portion extending radially outward from the flange pair, thus exposing the blade portion for cutting into a semiconductor wafer;
placing a semiconductor wafer having a known thickness onto a work surface for holding the semiconductor wafer onto the work surface during semiconductor wafer dicing steps;
operating the dicing saw for dicing the semiconductor wafer;
positioning the dicing saw spindle at a first spindle axis position above the work surface;
dicing the semiconductor wafer by making a first cut and a predetermined number of subsequent cuts into the wafer, the dicing blade diameter reducing with each cut thus reducing the blade portion exposure for cutting into the semiconductor wafer;
determining the blade portion exposure by measuring blade wear after a preselected number of cuts for automatically monitoring the blade portion exposure prior to subsequent dicing steps and providing a first stop movement signal when the blade portion exposed is at a minimum exposure and thus results in a minimum flange clearance;
calculating a separation distance between the work surface and the blade cutting edge and providing a second stop movement signal when a preselected minimum separation distance is measured;
and
stopping blade movement toward the work surface when any stop movement signal is received.

7 more elements

A method for automatically dicing a semiconductor wafer using a dicing saw having a spindle carrying a dicing blade and a work surface holding the semiconductor wafer, the spindle carrying the dicing blade within a flange pair for rotation of the dicing blade about a spindle axis and movement of the dicing blade for cutting the semiconductor wafer, the dicing blade having an outer diameter that is greater than a flange pair diameter for providing a blade exposed portion extending radially outward from the flange pair edge for cutting into the semiconductor wafer, the method useful in providing a safe flange clearance between an edge of the flange pair and the semiconductor wafer, the method comprising the steps of:

operating the dicing saw for movement of the spindle relative to the working surface for dicing the semiconductor wafer;
positioning the dicing saw spindle at a first spindle axis position above the work surface;
dicing the semiconductor wafer by making a first cut to a preselected depth into the semiconductor wafer, the dicing blade wearing with each cut thus reducing the blade exposed portion, each dicing step reducing the flange clearance between the flange pair edge and the semiconductor wafer for each subsequent dicing step and cut to the preselected depth;
moving the spindle to a second spindle axis position for moving the dicing blade closer to the work surface for making a subsequent cut into the semiconductor wafer to the preselected depth;
repeating the spindle moving and dicing steps for making subsequent cuts into the semiconductor wafer to the preselected depth;
sensing the position of the dicing blade edge for determining the dicing blade diameter after a preselected number of cuts;
and
calculating the flange clearance for automatically monitoring a remaining amount of blade exposed portion and thus the flange clearance for the wafer dicing steps.

5 more elements

Dependencies are inferred from the claim text.