1. A total temperature probe comprising:
a hollow elongate shroud defined by a shroud wall that envelops a first cavity; the shroud wall comprising an inner skin and an outer skin which enclose a second cavity therebetween;
a temperature sensor mounted in the first cavity;
wherein, in use, fluid flow is received into the first cavity, passes through at least one aperture in the inner skin into the second cavity and thence passes out of the shroud through at least one aperture in the outer skin, such that heat conduction across the inner skin is minimal.
2. A total temperature probe as claimed in claim 1 wherein the inner skin and the outer skin are separated by a constant distance.
3. A total temperature probe as claimed in claim 1 wherein the first and second cavities are coextensive.
4. A total temperature probe as claimed in claim 1 wherein the shroud is annular.
5. A total temperature probe as claimed in claim 4 wherein the inner and outer skins are coaxial.
6. A total temperature probe as claimed in claim 1 wherein the shroud changes cross-sectional shape in the direction of fluid flow therethrough.
7. A total temperature probe as claimed in claim 6 wherein the shroud has a regular polygon cross-section at one or both of its ends.
8. A total temperature probe as claimed in claim 6 wherein the shroud has rectangular cross-section at an intermediate portion between its ends.
9. A total temperature probe as claimed in claim 1 wherein the temperature sensor comprises any one of the group comprising a thermocouple, a resistive temperature sensor or an optical temperature sensor.
10. A total temperature probe as claimed in claim 1 further comprising a pressure sensor.
11. A total temperature probe as claimed in claim 10 wherein the pressure sensor is located adjacent to the temperature sensor.
12. A total temperature probe as claimed in claim 10 wherein the temperature sensor also functions as a pressure sensor.
13. A total temperature probe as claimed in claim 10 wherein the pressure sensor is mounted in a tapping through the outer skin into the second cavity.
14. A total temperature probe as claimed in claim 1 wherein the at least one aperture in the inner skin is aligned with or downstream of the temperature sensor.
15. A total temperature probe as claimed in claim 1 wherein the at least one aperture in the outer skin is axially andor circumferentially displaced from the at least one aperture in the inner skin.
16. A total temperature probe as claimed in claim 1 wherein there is more than one aperture in the inner skin, the apertures being arranged in a regular array around the periphery of the inner skin.
17. A total temperature probe as claimed in claim 1 wherein there is more than one aperture in the outer skin, the apertures being arranged in a regular array around the periphery of the outer skin.
18. An arrangement comprising an array of total temperature probes as claimed in claim 1.
19. A gas turbine engine comprising a total temperature probe as claimed in claim 1.
20. A gas turbine engine comprising an arrangement as claimed in claim 18.
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 method of integrating a first element having a first contact structure with a second element having a second contact structure, comprising:
forming said first and second contact structures from a metal selected from copper, tungsten, nickel, gold or alloys thereof;
forming said first and second contact structures to have an upper surface below respective surfaces of said first and second elements by no more than 20 nm;
forming a conductive pad connected to at least said first contact structure;
bonding a material in said first element to a material in said second element such that said first contact structure is directly connected to said second contact structure; and
heating said first and second elements at a temperature less than 400\xb0 C. to increase pressure between said first and second contact structures.
2. The method recited in claim 1, comprising:
heating at a temperature below 350\xb0 C.
3. The method recited in claim 1, comprising:
removing a native oxide from at least one of the first and second contact structures.
4. The method recited in claim 1, wherein said heating comprises forming a mechanical connection between the first and second contact structures.
5. The method recited in claim 1, comprising:
forming a palladium layer on at least one of said first and second contact structures.
6. The method recited in claim 1, comprising:
forming said first and second contact structures to have an upper surface below respective surfaces of said first and second elements by no more than 10 nm.
7. The method recited in claim 1, comprising:
forming said second contact structure to have a lateral area smaller than a lateral area of said first contact structure.
8. The method recited in claim 1, comprising:
forming said second contact structure having a first perimeter completely within a second perimeter of said first contact structure.
9. The method recited in claim 1, comprising:
etching a surface of at least one of said first and second elements adjacent to said first and second contact structures, respectively.
10. The method recited in claim 1, comprising:
controlling a height of a surface of at least one of said first and second elements with respect to said first and second contact structures, respectively.
11. The method recited in claim 10, comprising:
controlling said height using chemo-mechanical polishing.
12. The method recited in claim 10, comprising:
controlling said height using etching of said surface.
13. The method recited in claim 10, comprising:
controlling said height using a metal layer formed on said contact structures.
14. The method recited in claim 1, comprising:
heating said first and second elements after bonding to thermally expand at least one of said first and second contact structures.
15. The method recited in claim 1, comprising:
thinning one of said first and second elements after said bonding; and
performing said heating after said thinning.
16. The method recited in claim 1, comprising:
preferentially heating said first and second contact structures with respect to said materials of said first and second elements.
17. The method recited in claim 1, wherein said 20 nm is an average distance over an extent of the first and second contact structures.
18. An integration method, comprising:
forming a first contact structure in a first element electrically connected to a conductive pad, said first element having a first substrate;
forming a second element having at least one second contact structure;
forming said first and second contact structures to have an upper surface below respective surfaces of said first substrate and second element by no more than 20 nm;
removing a portion of said first substrate;
bonding said first substrate to said second element after said removing; and
directly contacting said first contact structure with said second contact structure.
19. The method recited in claim 18, wherein said 20 nm is an average distance over an extent of the first and second contact structures.
20. The method recited in claim 18, comprising:
forming said first and second contact structures to have an upper surface below respective surfaces of said first and second elements by no more than 10 nm.
21. The method recited in claim 18, comprising:
forming said second contact structure to have a lateral area smaller than a lateral area of said first contact structure.
22. The method recited in claim 18, comprising:
forming said second contact structure having a first perimeter completely within a second perimeter of said first contact structure.
23. The method recited in claim 18, comprising:
etching a surface of at least one of said first and second elements adjacent to said first and second contact structures, respectively.
24. The method recited in claim 18, comprising:
controlling a height of a surface of at least one of said first and second elements with respect to said first and second contact structures, respectively.
25. The method recited in claim 24, comprising:
controlling said height using chemo-mechanical polishing.
26. The method recited in claim 24, comprising:
controlling said height using etching of said surface.
27. The method recited in claim 24, comprising:
controlling said height using a metal layer formed on said contact structures.
28. The method recited in claim 18, comprising:
heating said first and second elements after said bonding to thermally expand at least one of said first and second contact structures.
29. The method recited in claim 18, comprising:
thinning one of said first and second elements after said bonding; and
performing said heating after said thinning.
30. The method recited in claim 18, comprising:
preferentially heating said first and second contact structures with respect to said materials of said first and second elements.
31. The method recited in claim 18, comprising:
heating said first and second elements at a temperature to increase pressure between said first and second contact structures.
32. The method recited in claim 31, comprising:
heating said first and second elements at a temperature to reduce the resistance of contact between said first and second contact structures.
33. The method recited in claim 31, comprising:
heating at a temperature less than 400\xb0 C.