Fabrication techniques to enhance pressure uniformity in anodically bonded vapor cells

A wafer configuration for fabricating vapor cells, comprising:

• a first wafer comprising a plurality of vapor cell dies, the first wafer having an interior surface region and a perimeter, the first wafer having a first diameter;
• a second wafer anodically bonded to a first side of the first wafer over the vapor cell dies, the second wafer having a second diameter that is substantially the same as the first diameter;
• a third wafer located over the vapor cell dies on a second side of the first wafer opposite from the second wafer, the third wafer having a third diameter that is substantially the same as the first and second diameters;
• and
• a sacrificial wafer located over the third wafer, the sacrificial wafer having a diameter that is larger than the first, second and third diameters;
• wherein the diameter of the sacrificial wafer is sufficiently large to prevent arcing when the third wafer is anodically bonded to the first wafer.

A method of fabricating a plurality of vapor cells, the method comprising:

• forming a plurality of vapor cell dies in a silicon wafer having a first diameter;
• anodically bonding a first glass wafer to a first side of the silicon wafer over the vapor cell dies, the first glass wafer having a second diameter that is substantially the same as the first diameter;
• positioning a second glass wafer over the vapor cell dies on a second side of the silicon wafer opposite from the first glass wafer, the second glass wafer having a third diameter that is substantially the same as the first and second diameters;
• placing a sacrificial glass wafer over the second glass wafer, the sacrificial glass wafer having a diameter that is larger than the first, second and third diameters;
• locating a metallized bond plate over the sacrificial glass wafer;
• and
• anodically bonding the second glass wafer to the second side of the silicon wafer when a voltage is applied to the metallized bond plate while the sacrificial glass wafer is in place, the diameter of the sacrificial glass wafer sufficiently large to prevent arcing when the voltage is applied to the metallized bond plate.