Semiconductor device fabrication methods
Methods for fabricating semiconductor devices, such as complementary metal-oxide-semiconductor (CMOS) imagers, include fabricating transistors and other low-elevation features on an active surface of a fabrication substrate, and fabricating contact plugs, conductive lines, external contacts, and other higher-elevation features on the back side of the fabrication substrate. Semiconductor devices with transistors on the active surface and contact plugs that extend through the substrate are also disclosed, as are electronic devices including such semiconductor devices.
1. A method for fabricating a semiconductor device, comprising:
fabricating a fabrication substrate having an active surface and an opposing back side;
fabricating at least one of transistors and capacitors at the active surface of the fabrication substrate;
disposing an imperforate dielectric material over the at least one of the transistors and the capacitors;
subsequently forming contact openings associated with the at least one of the transistors and the capacitors in the fabrication substrate with the dielectric material remaining imperforate;
introducing conductive material into the contact openings to operatively connect to respective transistors or capacitors; and
fabricating laterally extending conductive elements over the back side of the fabrication substrate and in communication with the conductive material in the contact openings, wherein at least one laterally extending conductive element operatively connected to a first transistor or capacitor extends laterally underneath a second, different transistor or capacitor to which the laterally extending conductive element is not operatively connected.
2. The method of claim 1 , wherein disposing the imperforate dielectric material comprises disposing the imperforate dielectric material to have a thickness of about a half a micron or less.
3. The method of claim 1 , further comprising:
planarizing a surface of the imperforate dielectric material.
4. The method of claim 3 , wherein planarizing is effected before forming the contact openings.
5. The method of claim 3 , further comprising:
securing the planarized surface of the imperforate dielectric material to a carrier.
6. The method of claim 5 , wherein securing is effected before forming the contact openings.
7. The method of claim 5 , further comprising:
removing material from a back side of the fabrication substrate before forming the contact openings.
8. The method of claim 7 , wherein removing material comprises grinding the back side of the fabrication substrate.
9. The method of claim 1 , wherein fabricating the at least one of the transistor and the capacitor comprises fabricating at least one transistor and wherein forming the contact openings comprises forming the contact openings to extend to a source or a drain of the at least one transistor or to a gate of the at least one transistor.
10. The method of claim 1 , wherein fabricating the at least one of the transistor and the capacitor comprises fabricating a capacitor and wherein forming the contact openings comprises forming the contact openings to communicate with an electrode of the capacitor.
11. The method of claim 1 , wherein the laterally extending conductive elements are not confined to a periphery of the fabrication substrate.
12. The method of claim 1 , wherein no laterally extending conductive elements extend over the active surface.
13. A method for fabricating a semiconductor device, comprising:
fabricating a fabrication substrate having an active surface and an opposing back side;
fabricating transistors at the active surface of the fabrication substrate;
fabricating at least one capacitor laterally adjacent at least one of the transistors at the active surface of the fabrication substrate;
disposing a dielectric material on the active surface over the transistors and the at least one capacitor;
subsequently forming contact openings from a back side of the fabrication substrate to at least some of the transistors or at least some of the transistors and the at least one capacitor;
introducing conductive material into the contact openings; and
fabricating laterally extending conductive elements over the back side of the fabrication substrate and in communication with the conductive material in the contact openings, wherein at least one laterally extending conductive element operatively connected to a first transistor extends laterally underneath a second, different transistor to which the laterally extending conductive element is not operatively connected.
14. The method of claim 13 , further comprising fabricating an array of image sensing elements comprising an array of photodiodes in the active surface of the fabrication substrate.
15. The method of claim 14 , wherein fabricating transistors comprises fabricating at least one of a transfer gate, a reset gate, a source follower gate, and a row select gate associated with at least one photodiode of the array.
16. The method of claim 13 , wherein disposing the dielectric material comprises disposing a dielectric material having a thickness of about a half a micron or less.
17. The method of claim 13 , further comprising:
planarizing a surface of the dielectric material.
18. The method of claim 13 , further comprising:
after disposing the dielectric material, securing a surface of the dielectric material to a carrier.
19. The method of claim 13 , wherein forming the contact openings comprises forming at least some contact openings to extend to a source or a drain of the at least some transistors.
20. The method of claim 13 , wherein forming contact openings comprises forming at least some contact openings to extend to a gate of the at least some transistors.
21. The method of claim 13 , wherein forming the contact openings comprises forming at least one of the contact openings to communicate with an electrode of the at least one capacitor.
22. The method of claim 13 , wherein the laterally extending conductive elements are not confined to a periphery of the fabrication substrate.
23. The method of claim 13 , wherein no laterally extending conductive elements extend over the active surface.
24. The method of claim 13 , further comprising:
fabricating at least one contact adjacent to or in communication with the at least one laterally extending conductive element.