1. In a bearing assembly comprising at least one bearing set, a lubricated ball bearing disposed in the at least one bearing set, the lubricated ball bearing comprising:
a core;
a lubricating coating applied to the ball bearing, the lubricating coating having a thickness that does not exceed approximately 1500 angstroms; and
an intermediate bonding layer formed as a single layer that substantially covers the core so as to be interposed between the core and the lubricating coating, the intermediate bonding layer substantially comprising material selected from a group that includes: ruthenium; osmium; cobalt; rhenium; iridium; palladium; nickel; and platinum, and the intermediate bonding layer having a thickness that does not exceed approximately 400 angstroms.
2. A lubricated ball bearing as defined in claim 1, wherein the intermediate bonding layer substantially prevents the lubricating coating from deforming or flaking during operation of the bearing assembly.
3. A lubricated ball bearing as defined in claim 1, wherein the materials that comprise both the intermediate bonding layer and the lubricating coating have substantially amorphous molecular structures.
4. A lubricated ball bearing as defined in claim 1, wherein chemical bonds existing both between the core and the intermediate bonding layer and between the intermediate bonding layer and the lubricating coating comprise intermetallic interfaces.
5. A lubricated ball bearing as defined in claim 1, wherein the bearing assembly is disposed in a vacuum environment.
6. The lubricated ball bearing as recited in claim 1, wherein the core substantially comprises one of: ceramic; and, tungsten carbide.
7. The lubricated ball bearing as recited in claim 1, wherein the intermediate bonding layer comprises a vapor deposited intermediate bonding layer.
8. The lubricated ball bearing as recited in claim 1, wherein the lubricating coating substantially comprises one of: gold; silver; and, palladium.
9. The lubricated ball bearing as recited in claim 1, wherein the intermediate bonding layer is substantially resistant to the formation of alloys with the core and the lubricating coating.
10. An x-ray tube, comprising:
a vacuum enclosure having disposed therein an electron-emitting cathode and an anode positioned to receive electrons emitted by the cathode; and
a bearing assembly rotatably supporting the anode, the bearing assembly comprising at least two bearing sets, each bearing set including a plurality of ball bearings, at least one ball bearing of the plurality of each bearing set comprising:
a metallic core;
a first coating applied to the metallic core, the first coating having a thickness falling in a range of about 10 angstroms to about 400 angstroms; and
a second coating applied to the first coating, the second coating comprising a lubricating surface for the ball bearing and having a thickness falling in a range of about 1000 angstroms to about 1500 angstroms.
11. An x-ray tube as defined in claim 10, wherein the second coating is applied atop the first coating such that the material comprising the second coating has a substantially amorphous molecular structure.
12. An x-ray tube as defined in claim 10, wherein an intermetallic interface exists between the first coating and the second coating.
13. An x-ray tube as defined in claim 10, wherein the first and second coatings are applied via an electroplating process.
14. An x-ray tube as defined in claim 10, wherein the first coating comprises a material selected from a group that includes: nickel; ruthenium; osmium; cobalt; rhenium; iridium; palladium; and platinum.
15. An x-ray tube as defined in claim 10, wherein the second coating comprises a material selected from group that includes: silver; gold; and palladium.
16. The x-ray tube as recited in claim 10, wherein the metallic core substantially comprises steel.
17. The x-ray tube as recited in claim 10, wherein the first coating substantially comprises nickel.
18. The x-ray tube as recited in claim 10, wherein the second coating substantially comprises silver.
19. A bearing set comprising:
a first plurality of ball bearings, each bearing ball of the first plurality of ball bearings comprising:
a first core;
a first intermediate bonding layer substantially covering the first core; and
a first lubricating coating substantially covering the first intermediate bonding layer; and
a second plurality of ball bearings, each bearing ball of the second plurality of ball bearings comprising:
a second core;
a second intermediate bonding layer substantially covering the second core; and
a second lubricating coating substantially covering the second intermediate bonding layer, the second lubricating coating being different from the first lubricating coating.
20. A bearing set as defined in claim 19, wherein the materials that comprise both the first and second intermediate bonding layers and the first and second lubricating coatings have substantially amorphous molecular structures.
21. A bearing set as defined in claim 19, wherein the thickness of each of the first and second intermediate bonding layers does not exceed 400 angstroms, and wherein the thickness of each of the first and second lubricating coatings does not exceed 1,500 angstroms.
22. A bearing set as defined in claim 19, wherein the bearing set is disposed in an x-ray generating device.
23. The bearing set as recited in claim 19, wherein at least one of the first and second cores substantially comprises steel.
24. The bearing set as recited in claim 19, wherein at least one of the first and second intermediate bonding layers substantially comprises nickel.
25. The bearing set as recited in claim 19, wherein the first lubricating layer substantially comprises silver and the second lubricating layer substantially comprises palladium.
26. The bearing set as recited in claim 19, wherein the respective ball bearings of the first and second pluralities of ball bearings are arranged in alternating fashion, so that a ball bearing of the first plurality of ball bearings is disposed adjacent to two ball bearings of the second plurality of ball bearings.
27. A bearing set having a plurality of bearing balls, each of the bearing balls comprising:
a metallic core substantially comprising steel;
an intermediate bonding layer applied to the metallic core, the intermediate bonding layer having a thickness falling in a range of about 10 angstroms to about 400 angstroms and substantially comprising one of: nickel; ruthenium; osmium; cobalt; rhenium; iridium; palladium; and, platinum; and
a lubricating coating applied to the first coating, the lubricating coating having a thickness falling in a range of about 1000 angstroms to about 1500 angstroms and substantially comprising one of: silver; gold; and, palladium.
28. A bearing set having a plurality of bearing balls, at least one of the balls comprising:
a core that is one of: substantially non-ferrous; or, substantially non-metallic
an intermediate bonding layer that substantially covers the core, wherein the intermediate bonding layer substantially comprises material selected from a group that includes: ruthenium; osmium; cobalt; rhenium; iridium; palladium; and platinum; and
a lubricating coating that substantially covers the intermediate bonding layer.
29. The bearing set as recited in claim 28, wherein the core comprises ceramic material.
30. The bearing set as recited in claim 28, wherein the core comprises tungsten carbide.
31. The bearing set as recited in claim 28, wherein the intermediate bonding layer is chemically bonded to the lubricating coating.
32. A bearing set having a plurality of bearing balls, at least one of the balls comprising:
a core that is one of: substantially non-ferrous; or, substantially non-metallic
an intermediate bonding layer that substantially covers the core; and
a lubricating coating that substantially covers the intermediate bonding layer, wherein the lubricating coating substantially comprises one of: gold; silver; and, palladium.
33. The bearing set as recited in claim 32, wherein the core comprises ceramic material.
34. The bearing set as recited in claim 32, wherein the core comprises tungsten carbide.
35. The bearing set as recited in claim 32, wherein the intermediate bonding layer is chemically bonded to the lubricating coating.
36. A bearing set having a plurality of bearing balls, each of the bearing balls comprising:
a metallic core;
an intermediate bonding layer applied to the metallic core, the intermediate bonding layer substantially comprising one of: ruthenium; osmium; cobalt; rhenium; iridium; palladium; and platinum; and
a lubricating coating applied to the intermediate bonding layer, the lubricating coating substantially comprising palladium.
37. A bearing set having a plurality of bearing balls, each of the bearing balls comprising:
a metallic core;
an intermediate bonding layer applied to the metallic core, the intermediate bonding layer substantially comprising one of: ruthenium; osmium; cobalt; rhenium; iridium; palladium; and platinum; and
a lubricating coating applied to the intermediate bonding layer, the lubricating coating substantially comprising silver.
38. A bearing set having a plurality of bearing balls, each of the bearing balls comprising:
a metallic core;
an intermediate bonding layer applied to the metallic core, the intermediate bonding layer substantially comprising one of: ruthenium; osmium; cobalt; rhenium; iridium; palladium; and platinum; and
a lubricating coating applied to the intermediate bonding layer, the lubricating coating substantially comprising gold.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A bipolar junction transistor (BJT) comprising:
a collector made of p-type semiconductor material;
a base made of n-type well on the collector; and
an emitter comprising a p+ region on the base and a SiGe layer on the p+ region.
2. The BJT of claim 1, further comprising:
a first shallow trench isolation (STI) separating the emitter from the base; and
a second STI separating the base from the collector.
3. The BJT of claim 2, further comprising:
a first n+ contact on the base at a first side of the emitter and a second n+ contact on the base at a second side of the emitter;
a first p-well on the collector at a first side of the base and a second p-well on the collector at a second side of the base;
a first SiGe contact on the first p-well and a second SiGe contact on the second p-well;
an ILD layer on the emitter, the first n+ contact, the second n+ contact, the first SiGe contact, and the second SiGe contact; and
a plurality of contacts within the ILD layer connected respectively to the emitter, the first n+ contact, the second n+ contact, the first SiGe contact, and the second SiGe contact.
4. The BJT of claim 1, wherein the collector is on a silicon substrate.
5. The BJT of claim 1, wherein the p+ region comprises a p-type material selected from a group consisting essentially of boron, boron fluoride, indium, and combinations thereof.
6. The BJT of claim 3, wherein the SiGe layer of the emitter, the first SiGe contact, and the second SiGe contact have a thickness from about 1 nm to about 20 nm.
7. The BJT of claim 3, wherein the first n+ contact and the second n+ contact comprise a material selected from a group consisting essentially of arsenic, phosphorous, antimony, and combinations thereof.
8. A method for fabricating a bipolar junction transistor, comprising:
providing a semiconductor substrate comprising a collector, a base on the collector, a first p-well on the collector at a first side of the base and a second p-well on the collector at a second side of the base, a first shallow trench isolation (STI) separating the base from the collector, and a second STI within the base;
forming a sacrificial layer on the base, the first STI, the second STI, the first p-well, and the second p-well;
patterning a first photoresist on the sacrificial layer to expose an opening surrounded by the second STI;
implanting a p-type material through the sacrificial layer into an area of the base not covered by the first photoresist;
removing the sacrificial layer and the first photoresist;
forming a p+ region from the p-type implant at a top portion of the base;
placing a first mask on the base atop the first STI and the second STI to cover an area of the base and to expose the first p-well, the second p-well, and the p+ region;
etching the first p-well, the second p-well, and the p+ region, exposed by the first mask; and
forming a SiGe layer on the etched first p-well to be a first SiGe contact, on the etched second p-well to be a second SiGe contact, and on the etched p+ region to form an emitter comprising the p+ region and the SiGe layer on the p+ region.
9. The method of claim 8, further comprising:
patterning a second photoresist on the SiGe layer to expose a first area of the base on a first side of the emitter not covered by the SiGe layer, and to expose a second area of the base on a second side of the emitter not covered by the SiGe layer;
implanting a n-type material into the area of the base not covered by the second photoresist to form a first n+ contact on the first side of the emitter and a second n+ contact on the second side of the emitter;
removing the second photoresist;
forming an inter-level dielectric (ILD) layer on the first SiGe contact, the second SiGe contact, the SiGe layer of the emitter, the first n+ contact, and the second n+ contact; and
forming a plurality of contacts within the ILD layer connected to the first SiGe contact, the second SiGe contact, the SiGe layer of the emitter, the first n+ contact, and the second n+ contact.
10. The method of claim 8, wherein placing a first mask on the base atop the first STI and the second STI comprises placing an SiN hard mask on the base atop the first STI and the second STI.
11. The method of claim 8, wherein forming a SiGe layer comprises forming the SiGe layer by epitaxy.
12. The method of claim 8, wherein forming a SiGe layer comprises forming the SiGe layer from a silicon source SiH4 and a Ge source GeH4.
13. The method of claim 8, wherein implanting a p-type material comprises implanting a material selected from a group consisting essentially of boron, boron fluoride, indium, and combinations thereof.
14. The method of claim 8, wherein forming a p+ region comprises forming the p+ region from the implanted p-type material by a rapid thermal diffusion process.
15. The method of claim 8, wherein etching the first p-well, the second p-well, and the p+ region, exposed by the first mask comprises a wet etch using Tetramethylammonium hydroxide (TMAH).
16. A bipolar junction transistor (BJT) comprising:
a collector made of p-type semiconductor material;
a base made of n-type well on the collector;
an emitter comprising a p+ region on the base and a SiGe layer on the p+ region;
a first shallow trench isolation (STI) separating the emitter from the base;
a second STI separating the base from the collector;
a first n+ contact on the base at a first side of the emitter and a second n+ contact on the base at a second side of the emitter;
a first p-well on the collector at a first side of the base and a second p-well on the collector at a second side of the base; and
a first SiGe contact on the first p-well and a second SiGe contact on the second p-well.
17. The BJT of claim 16, further comprising:
an ILD layer on the emitter, the first n+ contact, the second n+ contact, the first SiGe contact, and the second SiGe contact; and
a plurality of contacts within the ILD layer connected respectively to the emitter, the first n+ contact, the second n+ contact, the first SiGe contact, and the second SiGe contact.
18. The BJT of claim 16, wherein the p+ region comprises a p-type material selected from a group consisting essentially of boron, boron fluoride, indium, and combinations thereof.
19. The BJT of claim 16, wherein the SiGe layer of the emitter, the first SiGe contact, and the second SiGe contact have a thickness from about 1 nm to about 20 nm.
20. The BJT of claim 16, wherein the first n+ contact and the second n+ contact comprise a material selected from a group consisting essentially of arsenic, phosphorous, antimony, and combinations thereof.