Chuck for supporting wafers with a fluid
View Patent ↗A method of relieving surface stress on a thin wafer by removing a small portion of the wafer substrate, the substrate being removed by applying a warm solution of KOH to the backside of the wafer while the wafer spins. The wafer may be supported on a rotatable platform adapted to direct the flow of chilled, deionized water underneath the device side of the wafer. The chilled water supports the wafer and protects the devices built-up on the wafer from the corrosive effects of KOH and from thermal damage.
1. A system for supporting a wafer with a fluid, said system comprising:
a rotatable chuck adapted to support a wafer, said chuck having an axis, a surface upon which a wafer may rest, an edge, a sidewall extending axially from the edge of the chuck and an opening disposed on the surface of the chuck;
a fluid supply tube in fluid communication with the opening;
a supply of fluid in fluid communication with the fluid supply tube;
a fluid control system operable to control the flow of fluid over the surface of the chuck; and
a supply of KOH and a KOH flow control system operably connected to the supply of KOH, said KOH flow control system operable to pump KOH onto a backside of the wafer when the wafer is supported on the chuck.
2. The system of claim 1 wherein the fluid control system and the fluid supply tube are adapted such that fluids flowing over the surface of the chuck have a circumferentially directed angular momentum sufficient to cause a wafer disposed on the chuck to spin.
3. The system of claim 1 further comprising at least one bump adapted to support a wafer, said bump disposed on the chuck.
4. The system of claim 1 further comprising a nozzle disposed above the chuck, said nozzle in fluid communication with a supply of KOH, and a means for controlling the flow of KOH through the nozzle.
5. The system of claim 4 wherein the fluid is deionized water chilled to a temperature between about 5° Celsius and about 15° Celsius.
6. The system of claim 1 further comprising a vacuum source in fluid communication with the fluid supply tube.
7. A system for supporting a wafer with a fluid, said system comprising:
a chuck having an axis, a surface, an edge and a sidewall extending axially from the edge of the chuck;
a bump disposed on the chuck, said bump extending axially from the surface of the chuck and said bump being adapted to support a wafer;
a nozzle disposed in the bump;
a fluid supply tube in fluid communication with the nozzle;
a supply of fluid in fluid communication with the fluid supply tube; and
a fluid control system operable to control the flow of fluid through the nozzle.
8. The system of claim 7 wherein the nozzle is a circumferentially facing nozzle.
9. The system of claim 7 further comprising a second nozzle disposed above the chuck, said second nozzle in fluid communication with a supply of KOH, and a means for controlling the flow of KOH through the second nozzle.
10. The system of claim 9 wherein the fluid is deionized water chilled to a temperature between about 5° Celsius and about 15° Celsius.