We claim:
1. A polishing head for positioning a substrate having a surface on a polishing pad of a polishing apparatus, the polishing head comprising:
a subcarrier plate having an outer surface;
an annular first membrane coupled to the subcarrier plate, the first membrane having a receiving surface adapted to receive the substrate thereon, and a lip adapted to seal with a backside of the substrate to define a first chamber between the backside of the substrate and the outer surface of the subcarrier plate;
a second membrane positioned above the first membrane, the second membrane coupled to the subcarrier plate to define a second chamber between an inner surface of the second membrane and the outer surface of the subcarrier plate; and
wherein during a polishing operation pressurized fluid introduced into the second chamber causes it to expand outward to exert a force on a portion of the backside of the substrate, thereby pressing a predetermined area of the surface of the substrate against the polishing pad.
2. A polishing head according to claim 1, wherein the predetermined area is directly proportional to the pressure of the fluid introduced into the second chamber.
3. A polishing head according to claim 1, wherein a pressurized fluid at a lower pressure than that introduced into the second chamber is introduced into the first chamber to press the surface of the substrate against the polishing pad.
4. A polishing head according to claim 3, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the first chamber and the second chamber.
5. A polishing head according to claim 1, wherein the second membrane comprise a skirt portion and a lower surface portion, and wherein the skirt portion comprises a first hardness and the lower surface portion comprises a second hardness.
6. A polishing head according to claim 5, wherein the second hardness is less than the first hardness.
7. A polishing head according to claim 1, wherein the second membrane comprise a skirt portion and a lower surface portion, and wherein the lower surface portion comprises a thickness lower than a thickness of the skirt portion.
8. A method of polishing a surface of a substrate using an apparatus comprising a polishing pad, and a polishing head having a subcarrier plate with an outer surface, the method comprising steps of:
providing an annular first membrane coupled to the subcarrier plate, the first membrane having a receiving surface adapted to receive the substrate thereon, and a lip adapted to seal with a backside of the substrate to define a first chamber between the backside of the substrate and the outer surface of the subcarrier plate;
providing a second membrane positioned above the first membrane, the second membrane coupled to the subcarrier plate and to define a second chamber between an inner surface of the second membrane and the outer surface of the subcarrier plate;
positioning the substrate on the receiving surface of the first membrane;
pressing the surface of the substrate against the polishing pad by introducing a pressurized fluid into the second chamber to cause the second membrane to exert a force on a portion of the backside of the substrate, thereby pressing a predetermined area of the surface of the substrate against the polishing pad; and
providing relative motion between the subcarrier and the polishing pad to polish the surface of the substrate.
9. A method according to claim 8, wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of providing pressurized fluid having a pressure selected to provide a desired predetermined area.
10. A method according to claim 8, wherein the step of pressing the surface of the substrate against the polishing pad further comprises the step of introducing into the first chamber a pressurized fluid at a lower pressure than that introduced into the second chamber to press the surface of the substrate against the polishing pad.
11. A method according to claim 10, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the first chamber and the second chamber, and wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of selecting the pressure of the fluids introduced into the first chamber and the second chamber to provide a desired predetermined area.
12. A semiconductor substrate polished according to the method of claim 8.
13. A polishing head for positioning a substrate having a surface on a polishing pad of a polishing apparatus, the polishing head comprising:
a subcarrier plate having an outer surface;
a spacer coupled to a peripheral outer edge of the subcarrier;
a first membrane coupled to the subcarrier plate via the spacer, the first membrane separated from the subcarrier plate outer surface by a thickness of the spacer and extending substantially across the outer surface of the subcarrier plate to define a first chamber between an inner surface of the first membrane and the outer surface of the subcarrier plate, and the first membrane having a receiving surface adapted to receive the substrate thereon;
a second membrane positioned above the first membrane, the second membrane coupled to the subcarrier plate to define a second chamber between an inner surface of the second membrane and the outer surface of the subcarrier plate; and
wherein during a polishing operation pressurized fluid introduced into the second chamber causes it to exert a force on the first membrane to press a portion of the surface of the substrate having a predetermined area against the polishing pad.
14. A polishing head according to claim 13, wherein the force exerted on the second membrane causes it to expand outward to press against the inner surface of the first membrane.
15. A polishing head according to claim 13, wherein the predetermined area is directly proportional to the pressure of the fluid introduced into the second chamber.
16. A polishing head according to claim 13, wherein a pressurized fluid at a lower pressure than that introduced into the second chamber is introduced into the first chamber to cause the first membrane to press a portion of the surface of the substrate against the polishing pad.
17. A polishing head according to claim 16, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the first chamber and the second chamber.
18. A polishing head according to claim 16, wherein the first membrane comprises a thickness and a plurality of holes extending through the thickness to the receiving surface for applying pressurized fluid directly to the substrate.
19. A polishing head according to claim 18, wherein the number, size and shape of the plurality of holes is selected to provide sufficient frictional forces between the receiving surface and the substrate to impart rotational energy to substrate.
20. A polishing head according to claim 13, wherein the second membrane comprise a skirt portion and a lower surface portion, and wherein the skirt portion comprises a first hardness and the lower surface portion comprises a second hardness.
21. A polishing head according to claim 20, wherein the second hardness is less than the first hardness.
22. A polishing head according to claim 13, wherein the second membrane comprise a skirt portion and a lower surface portion, and wherein the lower surface portion comprises a thickness lower than a thickness of the skirt portion.
23. A method of polishing a surface of a substrate using an apparatus comprising a polishing pad, and a polishing head having a subcarrier plate with an outer surface, the method comprising steps of:
providing a first membrane coupled to the subcarrier plate, the first membrane extending substantially across the outer surface of the subcarrier plate to define a first chamber between an inner surface of the first membrane and the outer surface of the subcarrier plate, the first membrane having a receiving surface adapted to receive the substrate thereon;
providing a second membrane positioned above the first membrane, the second membrane coupled to the subcarrier plate and to define a second chamber between an inner surface of the second membrane and the outer surface of the subcarrier plate;
positioning the substrate on the receiving surface of the first membrane;
pressing the surface of the substrate against the polishing pad by introducing a pressurized fluid into the second chamber to cause the second membrane to exert a force on the first membrane, thereby pressing a portion of the surface of the substrate having a predetermined area against the polishing pad; and
providing relative motion between the subcarrier and the polishing pad to polish the surface of the substrate.
24. A method according to claim 23, wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of providing pressurized fluid having a pressure selected to provide a desired predetermined area.
25. A method according to claim 23, wherein the step of pressing the surface of the substrate against the polishing pad further comprises the step of introducing into the first chamber a pressurized fluid at a lower pressure than that introduced into the second chamber to cause the first membrane to press a portion of the surface of the substrate against the polishing pad.
26. A method according to claim 25, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the first chamber and the second chamber, and wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of selecting the pressure of the fluids introduced into the first chamber and the second chamber to provide a desired predetermined area.
27. A semiconductor substrate polished according to the method of claim 23.
28. A polishing head for positioning a substrate having a surface on a polishing pad of a polishing apparatus, the polishing head comprising:
a subcarrier plate having an outer surface with a peripheral outer edge and a central portion;
a spacer coupled to the peripheral outer edge of the subcarrier; and
an annular membrane having a receiving surface adapted to receive the substrate thereon, the annular membrane having an outer edge coupled to the peripheral outer edge of the outer surface of the subcarrier plate via the spacer, and an inner edge coupled to the central portion of the outer surface of the subcarrier plate, the annular membrane separated from the outer surface by a thickness of the spacer to define an annular chamber between the membrane and the outer surface,
wherein during a polishing operation pressurized fluid introduced into the annular chamber causes it to expand outward to exert a force on a portion of a backside of the substrate, thereby pressing a predetermined area of the surface of the substrate against the polishing pad.
29. A polishing head according to claim 28, wherein the predetermined area is directly proportional to the pressure of the fluid introduced into the annular chamber.
30. A polishing head according to claim 28, wherein the receiving surface of the annular membrane seals with with the backside of the substrate to define a center chamber between the backside of the substrate, the receiving surface of the annular membrane and the outer surface of the subcarrier plate, and wherein a pressurized fluid at a lower pressure than that introduced into the annular chamber is introduced into the center chamber to press the surface of the substrate against the polishing pad.
31. A polishing head according to claim 30, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the annular chamber and the center chamber.
32. A polishing head according to claim 28, wherein the central portion of the outer surface of the subcarrier plate further comprises a piston slidably fitted within a cylinder in the subcarrier plate, and wherein the inner edge of the annular membrane is coupled to the piston, wherein pressurized fluid introduced into the cylinder repositions the piston, thereby altering the predetermined area of the surface of the substrate against the polishing pad.
33. A polishing head according to claim 28, wherein the annular membrane comprises a skirt portion and a lower surface portion, and wherein the skirt portion comprises a first hardness and the lower surface portion comprises a second hardness.
34. A polishing head according to claim 33, wherein the second hardness is less than the first hardness.
35. A polishing head according to claim 28, wherein the annular membrane comprises a skirt portion and a lower surface portion, and wherein the lower surface portion comprises a thickness lower than a thickness of the skirt portion.
36. A method of polishing a surface of a substrate using an apparatus comprising a polishing pad, and a polishing head having a subcarrier plate with an outer surface having a peripheral outer edge and a central portion, the method comprising steps of:
providing an annular membrane having a receiving surface adapted to receive the substrate thereon, the annular membrane having an outer edge coupled to the peripheral outer edge of the outer surface of the subcarrier plate via the spacer, and an inner edge coupled to the central portion of the outer surface of the subcarrier plate, the annular membrane separated from the outer surface by a thickness of the spacer to define an annular chamber between the membrane and the outer surface,
positioning the substrate on the receiving surface of the annular membrane;
pressing a predetermined area of the surface of the substrate against the polishing pad by introducing a pressurized fluid into the annular chamber to cause the annular membrane to exert a force on a portion of the backside of the substrate; and
providing relative motion between the subcarrier and the polishing pad to polish the surface of the substrate.
37. A method according to claim 36, wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of providing pressurized fluid having a pressure selected to provide a desired predetermined area.
38. A method according to claim 36, wherein the receiving surface of the annular membrane seals with with the backside of the substrate to define a center chamber between the backside of the substrate, the receiving surface of the annular membrane and the outer surface of the subcarrier plate, and wherein the step of pressing the surface of the substrate against the polishing pad further comprises the step of introducing into the center chamber a pressurized fluid at a lower pressure than that introduced into the annular chamber to press the surface of the substrate against the polishing pad.
39. A method according to claim 38, wherein the predetermined area is directly proportional to a difference between the pressure of the fluids introduced into the annular chamber and the center chamber, and wherein the step of pressing the surface of the substrate against the polishing pad comprises the step of selecting the pressure of the fluids introduced into the annular chamber and the center chamber to provide a desired predetermined area.
40. A method according to claim 36, wherein the inner edge of the annular membrane is coupled to a piston slidably fitted within a cylinder in the central portion of the subcarrier plate, and wherein the method further comprises the step of introducing a pressurized fluid into the cylinder to reposition the piston, thereby altering the predetermined area of the surface of the substrate against the polishing pad.
41. A semiconductor substrate polished according to the method of claim 36.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A dropper-type stabilized power circuit comprising:
a PNP-type power transistor for obtaining an output voltage by dropping an input voltage;
a high-temperature-leak compensating resistance provided between an emitter and a base of the power transistor;
a compensating resistance switch provided in series with the high-temperature-leak compensating resistance between the emitter and the base;
an output terminal for outputting voltage; and
compensating resistance switch controlling means for detecting a voltage of the output terminal and conducting the compensating resistance switch under normal operating conditions in which the input voltage is dropped so as to obtain the output voltage, and not conducting the compensating resistance switch when the detected voltage is higher than the output voltage of normal operating conditions and is not less than a predetermined value which is set to be not more than a value at which a current begins to flow from a collector to the emitter of the power transistor.
2. The stabilized power circuit set forth in claim 1 wherein, said compensating resistance switch controlling means includes:
an output voltage detecting circuit which detects the output voltage under normal operating conditions in which the input voltage is dropped so as to obtain the output voltage, and detects the output voltage, when there is an externally applied voltage to the output terminal, by including this voltage: and
a switch driving circuit which compares a voltage of the predetermined value with the output voltage detected by the output voltage detecting circuit so as to output a controlling signal for opening and closing the compensating resistance switch according to a result of comparison.
3. The stabilized power circuit set forth in claim 1, wherein,
said compensating resistance switch includes the PNP-type transistor,
said output voltage detecting circuit includes a voltage dividing resistance, and
said switch driving circuit includes a reference voltage circuit which generates a reference voltage corresponding to a voltage of the predetermined value, a comparator which compares the reference voltage and a divided voltage of the output voltage detected by the voltage dividing resistance so as to judge whether the output voltage is larger or smaller than the reference voltage, a resistance connected to an output terminal of the comparator, and an NPN-type transistor whose base is connected to the resistance.
4. The stabilized power circuit set forth in claim 1 wherein, said compensating resistance switch controlling means detects a voltage of the output terminal by using a voltage dividing resistance for output voltage feedback used for a voltage stabilizing operation.
5. The stabilized power circuit set forth in claim 1, further comprising operation stopping means for stopping a voltage stabilizing operation when a voltage of said output terminal becomes not less than the predetermined value.
6. The stabilized power circuit set forth in claim 5 wherein, said operation stopping means includes:
a power switch which conducts itself under normal operating conditions so as to supply power to the circuit which performs the voltage stabilizing operation, and does not conduct itself when a voltage of the output terminal becomes not less than the predetermined value so as to stop supplying power to the circuit which performs a voltage stabilizing operation, and
power switch controlling means which detects a voltage of the output terminal so as to control conductionnon-conduction of the power switch.
7. The stabilized power circuit set forth in claim 6 wherein, said compensating resistance switch controlling means also serves as said power switch controlling means.
8. The stabilized power circuit set forth in claim 7 wherein, a power supply line to the circuit which performs the voltage stabilizing operation is taken from an input line of the power transistor, and the high-temperature-leak compensating resistance is connected between any point of the power supply line and the base of the power transistor, and a switch which serves as the compensating resistance switch and as the power switch is provided between (1) a junction of the power supply line and the high-temperature-leak compensating resistance and (2) a junction of the power supply line and the input line.
9. The stabilized power circuit set forth in claim 5, further comprising a terminal for externally receiving an operation signal which operates said operation stopping means.
10. The stabilized power circuit set forth in claim 1 wherein, the predetermined value is equal to the input voltage.
11. The stabilized power circuit set forth in claim 10, wherein, said compensating resistance switch controlling means detects a voltage of the output terminal by using a voltage dividing resistance for output voltage feedback used for a voltage stabilizing operation.
12. The stabilized power circuit set forth in claim 11 further comprising operation stopping means which stops the voltage stabilizing operation when the voltage of the output terminal becomes not less than the predetermined value.
13. The stabilized power circuit set forth in claim 12 wherein, said operation stopping means includes:
a power switch which conducts itself under normal operating conditions so as to supply power to a circuit which performs the voltage stabilizing operation, and does not conduct itself when the voltage of the output terminal becomes not less than the predetermined value so as to stop supplying power to the circuit which performs the voltage stabilizing operation, and
power switch controlling means which detects the voltage of the output terminal so as to control conductionnon-conduction of the power switch.
14. The stabilized power circuit set forth in claim 13 wherein, said compensating resistance switch controlling means also serves as said power switch controlling means.
15. The stabilized power circuit set forth in claim 14 wherein, a power supply line to the circuit which performs the voltage stabilizing operation is taken from an input line of the power transistor, and the high-temperature-leak compensating resistance is connected between any point of the power supply line and the base of the power transistor, and a switch which serves as the compensating resistance switch and as the power switch is provided between (1) a junction of the power supply line and the high-temperature-leak compensating resistance and (2) a junction of the power supply line and the input line.
16. The stabilized power circuit set forth in claim 12 further comprising a terminal for externally receiving an operation signal which operates said operation stopping means.