Automatic sensing wafer blade and method for using
View Patent ↗An automatic sensing wafer blade for picking up wafers that is equipped with a sensor capable of self-diagnosing potential failure conditions of the blade and a method for using the wafer blade are described. The automatic sensing wafer blade is equipped with a V-shaped seal ring on a top surface, and a sensor of either a limit switch or a capacitance sensor for sensing the presence or absence of a wafer on top of the wafer blade. The automatic sensing wafer blade is further capable of self-diagnosing any potential failure conditions of the function of the wafer blade due to contaminating particles, or contaminating liquid on the wafer surface, or due to an aged or malfunctioning seal ring on top of the wafer blade.
1. An automatic sensing wafer blade for picking-up wafers comprising:
a blade body of generally circular shape having a first thickness;
a blade handle of elongated shape integral at one end with said blade body, said blade handle having a second thickness;
a first plurality of stops formed on a top surface of said blade body circumferentially spaced-apart from each other adapted for contacting a bottom surface of a wafer;
a seal ring circumferentially situated on said top surface of the blade body;
a second plurality of vacuum holes in said top surface of the blade body situated within said seal ring; said second plurality of vacuum holes in fluid communication with a vacuum passageway in said blade body and said blade handle;
at least one sensor mounted on said top surface of the blade body situated within said seal ring for sensing the presence of a wafer positioned on said top surface of the blade body; and
a recording device for recording the status of detection of a wafer on top of said at least one sensor.
2. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said seal ring has a V-shaped cross-section.
3. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said seal ring has a V-shaped cross-section fabricated of rubber.
4. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said at least one sensor is a capacitance sensor.
5. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said at least one sensor is a limit switch.
6. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said seal ring has a height larger than a thickness of said first plurality of stops.
7. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said seal ring has a height larger than a thickness of said at least one sensor mounted on said top surface of the blade body.
8. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said first plurality of stops being formed of a material that has an elasticity sufficiently large to prevent the imposition of an impact load onto said wafer during a wafer pick-up process.
9. An automatic sensing wafer blade for picking-up wafers according to claim 1 , wherein said first plurality of stops being formed of a rubber material.
10. A method for picking-up wafers by an automatic sensing wafer blade comprising the steps of:
providing a wafer blade having a blade body of generally circular shape, a blade handle of elongated shape integral at one end with said blade body, a first plurality of stops formed on a top surface of said blade body circumferentially spaced-apart from each other adapted for contacting a bottom surface of a wafer, a seal ring circumferentially situated on said top surface of the blade body, a second plurality of vacuum holes in said top surface of the blade body situated within said seal ring; said second plurality of vacuum holes in fluid communication with a vacuum passageway in said blade body and said blade handle, and at least one sensor mounted on said top surface of the blade body situated within said seal ring;
withdrawing air from said second plurality of vacuum holes in two separate steps while positioning a wafer on top of said blade body; and
monitoring an electronic signal produced by said at least one sensor to verify the proper functioning of said wafer blade.
11. A method for picking-up wafers by an automatic sensing wafer blade according to claim 10 further comprising the step of controlling the withdrawing of air from said second plurality of vacuum holes by a two-stage vacuum valve.
12. A method for picking-up wafers by an automatic sensing wafer blade according to claim 10 further comprising the step of providing said first plurality of stops fabricated of a material having sufficient elasticity so as not to impact a wafer during the pick-up process.
13. A method for picking-up wafers by an automatic sensing wafer blade according to claim 10 further comprising the step of providing said first plurality of stops fabricated of an elastomer.
14. A method for picking-up wafers by an automatic sensing wafer blade according to claim 10 further comprising the step of providing said at least one sensor in a limit switch.
15. A method for picking-up wafers by an automatic sensing wafer blade according to claim 10 further comprising the step of providing said at least one sensor in a capacitance sensor.
16. A method for picking-up wafers by an automatic sensing wafer blade comprising the step of:
providing a wafer blade having a blade body of generally circular shape, a blade handle of elongated shape integral at one end with said blade body, a first plurality of stops formed on a top surface of said blade body circumferentially spaced-apart from each other adapted for contacting a bottom surface of a wafer, a seal ring circumferentially situated on said top surface of the blade body, a second plurality of vacuum holes in said top surface of the blade body situated within said seal rifle; said second plurality of vacuum holes in fluid communication with a vacuum passageway in said blade body and said blade handle, and at least one sensor mounted on said top surface of the blade body situated within said seal ring;
testing the sealing efficiency of said seal ring;
withdrawing air from said second plurality of vacuum holes while positioning a wafer on top of said blade body; and
monitoring an electronic signal produced by said at least one sensor to verify the proper functioning of said wafer blade.
17. A method for picking-up wafers by an automatic sensing wafer blade according to claim 16 further comprising the step of testing for particle contamination on said top surface of the blade body.
18. A method for picking-up wafers by an automatic sensing wafer blade according to claim 16 further comprising the step of testing for liquid chemical contamination on said top surface of the blade body.