Patent ID: 7661544

Claim:
A boat for supporting a plurality of semiconductor wafers, all of the same radius R, in a vertical stack for processing, where R equals one and only one of either 100 millimeters (mm), 150 mm, or 225 mm, the boat comprising: a plurality of vertical support members spaced around a vertical axis and each having a plurality of vertically spaced slots therein each horizontally aligned with a slot in each of the other vertical support members; each slot having an upwardly facing surface therein having a recessed wafer supporting area thereon recessed below the upwardly facing surface and forming an inwardly facing vertical step in the upwardly facing surface, the vertical steps each facing the vertical axis and being spaced at least a distance R+1 mm from the vertical axis, wherein the steps are sufficiently close to the vertical axis to be effective to constrain wafers having a radius R supported on the recessed wafer supporting areas from sliding off of a wafer supporting area within one of the horizontally aligned slots in one of the other vertical support members; the plurality of vertical support members including at least three vertical members, adjacent ones of which are spaced less than 180 degrees apart around the vertical axis; two adjacent ones of the vertical support members being spaced forward of the vertical axis and spaced sufficiently apart, and having the slots therein extending to a distance of at least R+5 mm from the vertical axis, to allow sufficient horizontal clearance between said two adjacent ones of the vertical support members for wafers of radius R to be loaded onto, and removed from, the boat without contacting said two adjacent ones of the vertical support members, while the steps on said two adjacent ones of the vertical support members are insufficiently spaced to allow wafers to be loaded or unloaded between the steps without being raised above the steps; and at least one of the vertical support members being spaced rearward of the vertical axis.