Detachable edge ring for thermal processing support towers

1. A tower and edge ring assembly, comprising:

a tower for supporting a plurality of wafers in a vertical spaced parallel relationship on wafer support areas of the tower disposed at first radial distances from a center of the tower; and

edge rings detachably supported on and included in the tower and interleaved with and spaced from the wafers, each of the edge rings being annularly shaped about a central ring axis, having a central aperture over at least most of the areas of the wafers and extending radially outwardly from a periphery of the wafers, and including at least one interlocking edge extending at least partially along a radius from the central ring axis to detachably engage the tower and thereby interlock the each edge ring to the tower;

wherein the tower comprises

two bases, and

a plurality of legs extending vertically along a central tower axis and fixed to the two bases, wherein each of the legs includes fingers which extend horizontally from vertically extending portions of the legs and wherein each of the fingers includes a wafer support surface for supporting a first wafer and a lower and ring support surface disposed radially outwardly from the central ring axis for supporting the each edge ring below the first wafer; and

wherein the each edge ring includes a plurality of radially inner recesses adjacent the central aperture, forming the at least one interlocking edge to engage sides of the fingers, and including segment portions of the each ring which are disposed radially outwardly of the recesses and are supportable on the edge ring support surfaces.

2. The assembly of claim 1 , wherein the edge rings have an inner diameter within a range that is larger than and smaller than the diameters of the wafers by no more than 10 mm.

3. The assembly of claim 1 , wherein the edge rings and the tower are randomly oriented polycrystalline silicon edge rings and a silicon tower.

4. A tower and edge ring assembly, comprising:

a tower for supporting a plurality of wafers in a vertical spaced parallel relationship on wafer support areas of the tower disposed at first radial distances from a center of the tower; and

edge rings detachably supported on and included in the tower and interleaved with and spaced from the wafers, each of the edge rings being annularly shaped about a central ring axis, having a central aperture over at least most of the areas of the wafers and extending radially outwardly from a periphery of the wafers, and including at least one interlocking edge extending at least partially along a radius from the central ring axis to detachably engage the tower and thereby interlock the each edge ring to the tower;

wherein the tower comprises

two bases, and

a plurality of legs extending vertically along a central tower axis and fixed to the two bases, wherein each of the legs includes fingers which extend horizontally from vertically extending portions of the legs and wherein each of the fingers includes a wafer support surface for supporting a first wafer and a lower and ring support surface disposed radially outwardly from the central ring axis for supporting the each edge ring below the first wafer;

wherein each of the fingers includes a wafer support surface for supporting a first wafer and a higher and radially outward edge ring support surface for supporting one of the edge rings above the first wafer;

wherein each edge ring includes

a plurality of radially outer one- or two-sided recesses forming the at least one interlocking edge to engage the fingers, and

segment portions disposed radially inwardly of the recesses which are supportable on the edge ring support surfaces; and

wherein each edge ring includes two one-sided recesses each comprising two side flats and a step therebetween.

5. The assembly of claim 4 , wherein the fingers of two legs are formed with passage ways above the edge ring support surface which can horizontally pass a wider one of the side flats but the edge ring support areas cannot horizontally pass the wider one of the side flats.

6. The assembly of claim 5 , whereby, when one of the edge rings is passed in a first direction through the passage ways, the one edge ring can fall down when disposed in the first direction of the passage ways.

7. A tower and edge ring assembly, comprising:

a plurality of edge rings each formed annularly about an edge ring central axis, having a central aperture, and including two inner side flats disposed on a periphery of the each edge ring and separated by a first spacing, two outer side flats on the periphery and separated by a second spacing large then the first spacing, and two steps between respective pairs of the inner and outer side flats; and

a tower including

two bases,

a plurality of legs extending parallel to a tower central axis and joined to the bases, and

fingers formed in each of the legs and each including a wafer support surface disposed on a radially inner side the each finger with respect to the tower central axis for supporting a wafer, a edge ring support area disposed radially outwardly and vertically upwardly from the wafer support surface and sized to accommodate and support the inner side flats, and a passage way disposed radially inwardly and vertically upwardly from the edge ring support area for allowing passage therethrough of the outer side flats.

8. The assembly of claim 7 , whereby, after one of the edge rings has been inserted into the tower through the passage way from a first side of the finger, the outer side flat gravitationally falls and is interlocked on an opposed second side of the finger while the one edge ring is supported on the edge ring support area.

9. The assembly of claim 7 , wherein each of the edge rings comprises randomly oriented polycrystalline silicon.

10. An edge ring for being spaced apart from and between wafers supported in a wafer support tower, comprising:

a member annular about an axis and including

two outer side flats formed on an outer periphery of the member, extending parallel to an insertion axis, and separated by a first spacing;

two inner side flats formed on the outer periphery, extending parallel to the insertion axis, and separated by a second spacing smaller than the first spacing, and separated by a second spacing smaller than the first spacing, and

two steps connecting respective pairs of the inner and outer side flats.

11. The edge ring of claim 10 , wherein the member comprises randomly oriented polycrystalline silicon.