Semiconductor constructions and semiconductor device fabrication methods
View Patent ↗A method of fabricating a semiconductor device includes etching a substrate to form a recess, the substrate being formed on a backside of a semiconductor wafer, forming pores in the substrate in an area of the recess, and forming in the recess a material having a thermal conductivity which is greater than a thermal conductivity of the substrate. In another aspect, a method of fabricating a semiconductor device includes etching a substrate formed on a backside of a semiconductor wafer to form a recess in the substrate, and forming a sputter film in the recess, the sputter film including a first material having a coefficient of thermal expansion (CTE) which is at least substantially equal to a CTE of the substrate, and a second material having a thermal conductivity which is greater than a thermal conductivity of the substrate.
1. A method of fabricating a semiconductor device, comprising:
etching a substrate to form a recess, the substrate being formed on a backside of a semiconductor wafer;
forming pores in said substrate in an area of said recess; and
forming in said recess a material having a thermal conductivity which is greater than a thermal conductivity of said substrate.
2. The method of claim 1 , further comprising:
annealing said device such that said material diffuses into said pores,
wherein a portion of said substrate which includes said diffused material has a coefficient of thermal expansion (CTE) which is substantially equal to a CTE of said substrate.
3. The method of claim 1 , further comprising:
forming a protective coating on said substrate, said protective coating inhibiting damage to a device formed in said substrate during said forming said pores in said substrate.
4. The method of claim 3 , further comprising:
etching said protective coating to form an opening in said protective coating, said etching said substrate being performed through said opening.
5. The method of claim 1 , wherein said wafer includes a silicon-on-insulator wafer including a buried insulating layer which functions as a conversion stop layer in said forming said pores.
6. The method of claim 5 , wherein said material diffuses into said pores to form an interdiffusion layer between said recess and said buried insulating layer.
7. The method of claim 6 , wherein said interdiffusion layer includes a coefficient of thermal expansion (CTE) which is at least substantially equal to a CTE of said substrate at a region of said interdiffusion layer which is nearest said buried insulating layer, said CTE of said interdiffusion layer increasing in a direction toward said backside of said wafer.
8. The method of claim 6 , further comprising:
a barrier layer formed on a backside of said buried insulating layer which functions as a conversion stop layer,
wherein a thickness of a frontside of said wafer between an uppermost surface of said wafer and said barrier layer is in a range from about 10 to about 20% of a total thickness of said wafer, said interdiffusion layer comprises a thickness in a range from about 10 to about 20% of a total thickness of said wafer, and said material comprises a layer having a thickness in a range from about 60 to about 80% of a total thickness of said wafer.
9. The method of claim 1 , wherein said forming said pores includes implanting ions in said substrate in said area of said recess, a density of said pores being dependent upon an impurity doping concentration.
10. The method of claim 9 , wherein said pore density increases in a direction toward said backside of said wafer.
11. The method of claim 1 , wherein said etching said substrate includes reducing an original thickness of a wafer including said substrate by about one-half.
12. The method of claim 11 , wherein after said forming said material, a total thickness of said wafer is at least substantially the same as said original thickness.
13. The method of claim 1 , wherein said forming said material includes a low-temperature process including at least one of annealing, inter-diffusion, plating and silicidation.
14. The method of claim 1 , wherein said forming said pores includes anodic etching in a fluoride-containing, acidic electrolyte in which said wafer including said substrate is connected as an anode.
15. The method of claim 1 , wherein said material includes at least one of copper, aluminum, gold, tungsten, diamond and silicon carbide.
16. The method of claim 1 , wherein said material includes at least one of aluminum, copper, gold, blends of copper and tungsten (Cu—W), copper and molybdenum (Cu—Mo), silicon carbide particle-reinforced aluminum ([SiC]p/Al), carbon fiber-reinforced copper (C/Cu), carbon fiber-reinforced aluminum (C/Al), diamond particle-reinforced copper ([Diamond]p/Cu), and beryllia particle-reinforced beryllium ([BeO]p/Be), pyrolitic graphite, carbon/carbon (C/C) composites, carbon fiber-reinforced epoxy (C/Ep) and chemical vapor deposition (CVD) diamond.