Wafer boat with interference fit wafer supports

Abstract

A wafer boat including a base plate, a top plate, a plurality of support rods, and a plurality of wafer supports. The support rods are disposed about a perimeter of the base plate and extend between the base plate and the top plate, each support rod including a plurality slots that define a plurality of teeth. The wafer supports are received in a corresponding slot of each of the plurality of support rods and have a continuous open shape that includes a pair of leg sections that form an interference fit with at least two of the support rods. The base plate, the top plate, the support rods, and/or the wafer supports may be prepared by molding ceramic powder such as silicon carbide, sintering to vaporize any active impurity components, washing to dissolve any remaining active impurity components with an acid solution, and oxidizing to remove any residual active impurity components.

1 . A wafer boat comprising: 
 a base plate;    a top plate;    a plurality of support rods disposed about a perimeter of the base plate and extending between the base plate and the top plate, each support rod of the plurality of support rods having a first distal end that is attached to the base plate and a second distal end that is attached to the top plate, each support rod including a plurality slots formed therein that define a plurality of teeth; and    a plurality of wafer supports adapted to be received in a corresponding slot of each of the plurality of support rods, each of the plurality of wafer supports having a continuous open shape and including a pair of leg sections that form an interference fit with at least two of the plurality of support rods.    
   
   
       2 . The wafer boat of  claim 1 , wherein the plurality of support rods are sintered to the base plate and the top plate to form a single monolithic structure.  
   
   
       3 . The wafer boat of  claim 1 , wherein the base plate, the top plate, the plurality of support rods, and the plurality of wafer supports are formed from recrystallized silicon carbide having a pore size of approximately 15 μm.  
   
   
       4 . The wafer boat of  claim 1 , wherein the plurality of support rods includes first, second, and third support rods, the first and second support rods being disposed approximately one hundred and eighty degrees apart from one another about the perimeter of the base plate, and the third support rod being disposed on the perimeter of the base plate approximately ninety degrees apart from the first and second support rods.  
   
   
       5 . The wafer boat of  claim 4 , wherein the plurality of slots formed in each support rod of the plurality of support rods are evenly spaced.  
   
   
       6 . The wafer boat of  claim 4 , wherein the base plate has a generally circular shape having a central hole formed therein, the base plate including an expansion slot that extends radially outward from the central hole and through an outer periphery of the base plate.  
   
   
       7 . The wafer boat of  claim 6 , wherein the top plate has a generally circular shape having central hole formed therein, the top plate including an expansion slot that extends radially outward from the central hole in the top plate and through an outer periphery of the top plate.  
   
   
       8 . The wafer boat of  claim 7 , wherein the expansion slot in the top plate is aligned with the expansion slot in the base plate.  
   
   
       9 . The wafer boat of  claim 8 , wherein each of the plurality of wafer supports includes a continuous flat member having an open shape, the continuous flat member including a plurality of inter-connected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and adapted to support a wafer at approximately a 0.7R boundary region of the wafer where R is a radius of the wafer, each of the two arcuately curved sections being connected to a respective leg section of the pair of leg sections and terminating in a free distal end; 
 wherein each of the free distal ends is shaped to form the interference fit with a slot of a respective one of the at least two support rods.    
   
   
       10 . The wafer boat of  claim 6 , wherein the top plate has a C-shape, and wherein an open end of the C-shape is aligned with the expansion slot in the base plate.  
   
   
       11 . The wafer boat of  claim 10 , wherein each of the plurality of wafer supports includes a continuous flat member having an open shape, the continuous flat member including a plurality of inter-connected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and adapted to support a wafer at approximately a 0.7R boundary region of the wafer where R is a radius of the wafer, each of the two arcuately curved sections being connected to a respective leg section of the pair of leg sections and terminating in a free distal end; 
 wherein each of the free distal ends is shaped to form the interference fit with a slot of a respective one of the at least two support rods.    
   
   
       12 . The wafer boat of  claim 1 , wherein the plurality of slots formed in each support rod of the plurality of support rods are evenly spaced.  
   
   
       13 . The wafer boat of  claim 1 , wherein the plurality of support rods includes first, second, third, and fourth support rods, the first and second support rods being disposed approximately one hundred and eighty degrees apart from one another about the perimeter of the base plate, and the third and fourth support rods being disposed on the perimeter of the base plate at positions that are approximately equidistant from a position on the perimeter of the base plate that is spaced approximately ninety degrees apart from the first and second support rods.  
   
   
       14 . The wafer boat of  claim 13 , wherein each of the plurality of wafer supports includes a continuous flat member having an open shape, the continuous flat member including a plurality of inter-connected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and adapted to support a wafer at approximately a 0.7R boundary region of the wafer where R is a radius of the wafer, each of the two arcuately curved sections being connected to a respective leg section of the pair of leg sections and terminating in a free distal end; 
 wherein each of the free distal ends is shaped to form the interference fit with a slot of a respective one of the at least two support rods.    
   
   
       15 . The wafer boat of  claim 1 , wherein each of the plurality of wafer supports includes a continuous flat member having an open shape, the continuous flat member including a plurality of inter-connected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and adapted to support a wafer at approximately a 0.7R boundary region of the wafer where R is a radius of the wafer, each of the two arcuately curved sections being connected to a respective leg section of the pair of leg sections and terminating in a free distal end; 
 wherein each of the free distal ends is shaped to form the interference fit with a slot of a respective one of the at least two support rods.    
   
   
       16 . The wafer boat of  claim 15 , wherein the free distal ends of each continuous flat member are mitered to engage with the slot of a respective one of the at least two support rods along a line of contact.  
   
   
       17 . The wafer boat of  claim 1 , wherein the plurality of wafer supports include a first plurality of wafer supports adapted to support wafers having a first diameter and a second plurality of wafer supports adapted to support wafers having a second diameter that is different than the first diameter.  
   
   
       18 . The wafer boat of  claim 1 , wherein the plurality of wafer supports can be at least one of inserted in and removed from the plurality of slots formed in the plurality of supports rods, and wherein the pair of leg sections of each of the plurality of wafer supports removably forms an interference fit with a respective one of the at least two of the plurality of support rods.  
   
   
       19 . A wafer boat body adapted to receive a plurality of wafer supports, comprising: 
 a base plate;    a top plate;    a plurality of support rods disposed about a perimeter of the base plate and extending between the base plate and the top plate, each support rod of the plurality of support rods having a first distal end that is attached to the base plate and a second distal end that is attached to the top plate, each support rod including a plurality slots formed therein that define a plurality of teeth;    wherein a top surface of each of the plurality of teeth of each of the plurality of support rods is adapted to support a respective wafer support of the plurality of wafer supports; and    wherein corresponding slots in at least two of the plurality supports rods form an interference fit with portions of the respective wafer support.    
   
   
       20 . The wafer boat body of  claim 19 , wherein the plurality of support rods are sintered to the base plate and the top plate to form a single monolithic structure.  
   
   
       21 . The wafer boat body of  claim 19 , wherein the base plate, the top plate, and the plurality of support rods are formed from recrystallized silicon carbide having a pore size of approximately 15 μm.  
   
   
       22 . The wafer boat body of  claim 19 , wherein the plurality of support rods includes first, second, and third support rods, the first and second support rods being disposed approximately one hundred and eighty degrees apart from one another about the perimeter of the base plate, and the third support rod being disposed on the perimeter of the base plate approximately ninety degrees apart from the first and second support rods.  
   
   
       23 . The wafer boat body of  claim 22 , wherein the base plate has a generally circular shape having a central hole formed therein, the base plate including an expansion slot that extends radially outward from the central hole and through an outer periphery of the base plate.  
   
   
       24 . The wafer boat body of  claim 23 , wherein the top plate has a generally circular shape having central hole formed therein, the top plate including an expansion slot that extends radially outward from the central hole in the top plate and through an outer periphery of the top plate; and 
 wherein the expansion slot in the top plate is aligned with the expansion slot in the base plate.    
   
   
       25 . The wafer boat body of  claim 23 , wherein the top plate has a C-shape, and wherein an open end of the C-shape is aligned with the expansion slot in the base plate.  
   
   
       26 . The wafer boat body of  claim 19 , wherein the plurality of slots formed in each support rod of the plurality of support rods are evenly spaced.  
   
   
       27 . The wafer boat body of  claim 19 , wherein the plurality of support rods includes first, second, third, and fourth support rods, the first and second support rods being disposed approximately one hundred and eighty degrees apart from one another about the perimeter of the base plate, and the third and fourth support rods being disposed on the perimeter of the base plate at positions that are approximately equidistant from a position on the perimeter of the base plate that is spaced approximately ninety degrees apart from the first and second support rods.  
   
   
       28 . The wafer boat body of  claim 19 , wherein the plurality of slots in the at least two of the plurality of support rods are adapted to engage with the portions of the respective wafer support along a line of contact.  
   
   
       29 . A wafer support to support a wafer having a predetermined radius R for use in a wafer boat body having a plurality of vertical support rods, each of the plurality of vertical support rods including a plurality of slots formed therein that define a plurality of teeth, the wafer support comprising: 
 a continuous flat member having an open shape and including a plurality of interconnected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and adapted to support the wafer at approximately a 0.7R boundary region of the wafer, each of the two arcuately curved sections being connected to a respective leg section that terminates in a free distal end;    wherein each of the free distal ends of the continuous flat member is shaped to form an interference fit with a slot of a respective one of the plurality of vertical support rods.    
   
   
       30 . The wafer support of  claim 29 , wherein the continuous flat member is formed from a sintered ceramic material.  
   
   
       31 . The wafer support of  claim 30 , wherein the sintered ceramic material is recrystallized silicon carbide having a pore size of approximately 15 μm.  
   
   
       32 . The wafer support of  claim 29 , wherein the plurality of interconnected arcuately curved sections include first, second, and third arcuately curved sections, the first and second arcuately curved sections defining the arc of approximately ninety degrees and adapted to support the wafer at approximately the 0.7R boundary region of the wafer, the first and second arcuately curved sections being respectively connected to third arcuately curved section by first and second straight sections.  
   
   
       33 . The wafer support of  claim 32 , wherein the third arcuately curved section defines an arc of approximately sixty degrees.  
   
   
       34 . The wafer support of  claim 33 , wherein the continuous flat member further includes first and second rounded sections that respectively connect the first and second arcuately curved sections to each respective leg section.  
   
   
       35 . The wafer support of  claim 34 , wherein each of the free distal ends of the continuous flat member is mitered to engage with the slot of a respective one of the plurality of vertical support rods along a line of contact.  
   
   
       36 . The wafer support of  claim 34 , wherein the free distal ends of the continuous flat member can be displaced toward one another by approximately 2 mm without fracture.  
   
   
       37 . The wafer support of  claim 29 , wherein each of the free distal ends of the continuous flat member forms a removable interference fit with the slot of the respective one of the plurality of support rods.  
   
   
       38 . A method of configuring a wafer boat for use in semiconductor processing operations, the wafer boat including a plurality of vertical support rods disposed about a perimeter of the wafer boat, each of the plurality of vertical support rods having a plurality of slots formed therein that define a plurality of teeth, the method comprising acts of: 
 (a) receiving a wafer support formed from a continuous flat member having an open shape and including a plurality of inter-connected arcuately curved sections, two of the arcuately curved sections defining an arc of approximately ninety degrees and being connected to a respective leg section;    (b) flexing the respective leg sections toward one another;    (c) inserting the wafer support into corresponding slots in each of the plurality of vertical support rods during the act (b); and    (d) releasing the respective leg sections so that a portion of each respective leg section forms an interference fit with a respective one of the plurality of vertical support rods.    
   
   
       39 . The method of  claim 38 , further comprising acts of: 
 repeating acts (a) through (d) for each of a plurality of wafer supports.    
   
   
       40 . The method of  claim 38 , wherein the wafer support is a first wafer support, the method further comprising an act of: 
 removing a second wafer support from the corresponding slots in each of the plurality of vertical support rods prior to performing acts (a) through (d).    
   
   
       41 . The method of  claim 38 , wherein the wafer support is a first wafer support, the method further comprising an act of: 
 removing a second wafer support that has been damaged or broken from the corresponding slots in each of the plurality of vertical support rods prior to performing acts (a) through (d).    
   
   
       42 . The method of  claim 38 , wherein the wafer support is a first wafer support adapted to support a wafer having a first diameter, the method further comprising an act of: 
 removing a second wafer support adapted to support a wafer having a second diameter that is different than the first diameter from the corresponding slots in each of the plurality of vertical support rods prior to performing acts (a) through (d).    
   
   
       43 . The method of  claim 38 , further comprising an act of: 
 installing the wafer boat in a semiconductor furnace prior to performing any of acts (b) through (d).