Integrated filler capacitor cell device and corresponding manufacturing method
A semiconductor region includes an isolating region which delimits a working area of the semiconductor region. A trench is located in the working area and further extends into the isolating region. The trench is filled by an electrically conductive central portion that is insulated from the working area by an isolating enclosure. A cover region is positioned to cover at least a first part of the filled trench, wherein the first part is located in the working area. A dielectric layer is in contact with the filled trench. A metal silicide layer is located at least on the electrically conductive central portion of a second part of the filled trench, wherein the second part is not covered by the cover region.
1. A method, comprising:
forming an isolating region delimiting a working area of a first semiconductor region;
etching at least one trench in said working area;
filling the at least one trench with an electrically conductive central portion insulated from bottom and sides of said at least one trench by an isolating layer;
forming a cover region which covers at least a first part of said filled at least one trench, said cover region comprising at least one dielectric layer in contact with said filled at least one trench;
siliciding at least the electrically conductive central portion of a second part of said at least one trench which is not covered by the cover region;
making a first electrical contact to the first semiconductor region so as to form a first electrode of a filler capacitor cell device; and
making a second electrical contact to the silicided electrically conductive central portion so as to form a second electrode of the filler capacitor cell device.
2. The method according to claim 1 , wherein the first semiconductor region comprises a semiconductor well in a semiconductor substrate, the method further comprising electrically connecting a substrate electrical contact for the semiconductor substrate to the second electrical contact.
3. The method according to claim 1 , wherein forming the cover region comprises forming an electrically conductive layer which is insulated from the filled at least one trench and the working area of the first semiconductor region by said at least one dielectric layer and further comprising electrically connecting the electrically conductive layer to the second electrical contact.
4. The method according to claim 3 , wherein the at least one dielectric layer of the cover region comprises a transistor gate oxide layer.
5. The method according to claim 3 , wherein the at least one dielectric layer of the cover region comprises a stack of oxide-nitride-silicon oxide layers.
6. The method according to claim 1 , wherein etching at least one trench comprises etching a plurality of trenches which extend parallel to each other.
7. The method according to claim 6 , wherein forming the cover region comprises forming the cover region in the shape of a plate which covers the plurality of trenches at the working area.
8. The method according to claim 6 , wherein forming the cover region comprises forming the covering region in the shape of a plurality of strips arranged to cover only the filled plurality of trenches.
9. The method according to claim 8 , further comprising making electrical contact to the working area at locations between adjacent strips of said plurality of strips.
10. The method according to claim 6 , wherein forming the cover region comprises forming the covering region in the shape of a plurality of strips arranged to cover the working area between the filled plurality of trenches and extend partially over side edges of the filled plurality of trenches.
11. The method according to claim 10 , wherein the second electrical contact to the silicided electrically conductive central portion is positioned between adjacent strips of said plurality of strips.
12. The method according to claim 6 , wherein forming the cover region comprises forming the covering region in the shape of a plurality of strips arranged to cover the filled plurality of trenches and extend partially over side edges of the working area between the filled plurality of trenches.
13. The method according to claim 12 , wherein the second electrical contact to the silicided electrically conductive central portion is positioned adjacent a longitudinal end of each strip of said plurality of strips.
14. The method according to claim 1 , wherein said first part of said filled at least one trench is located in said working area.
15. The method according to claim 1 , wherein said at least one trench extends in depth to a level below the isolating region.
16. A method, comprising:
forming an isolating region delimiting a working area of a semiconductor well;
forming a pair of trenches in the working area;
filling each trench of the pair of trenches with an electrically conductive central portion enclosed in an isolating enclosure;
forming a first doped region in a portion of the semiconductor well located between the pair of trenches;
forming a cover region including a pair of strips overlying said pair of trenches, wherein each strip includes an electrically conductive layer insulated from a corresponding one of the pair of trenches by a dielectric layer and a sidewall spacer, wherein the sidewall spacer extends over a side part of the portion of the semiconductor well located between the pair of trenches;
siliciding the first doped region in the portion of the semiconductor well located between the pair of trenches which is not covered by the sidewall spacer;
siliciding a part of the electrically conductive central portion;
siliciding the electrically conductive layer;
electrically connecting to the silicided first doped region to provide a first electrode of a filler capacitor cell device; and
electrically connecting to the silicided part of the electrically conductive central portion and the silicided electrically conductive layer to provide a second electrode of the filler capacitor cell device.
17. The method according to claim 16 , further comprising:
forming a second doped region in another portion of the semiconductor well; and
electrically connecting between the second doped region and the silicided first doped region.
18. The method according to claim 16 , further comprising:
forming a doped surface region in the semiconductor well, said doped surface region located between the pair of trenches;
forming a second doped region in a portion of the semiconductor well and in contact with the doped surface region; and
electrically connecting between said first electrical contact and the second doped regions.
19. The method according to claim 16 , further comprising forming a buried doped region in the semiconductor well at a bottom of each trench of the pair of trenches.
20. A method, comprising:
forming an isolating region delimiting a working area of a semiconductor well;
forming a pair of trenches in the working area;
filling each trench of the pair of trenches with an electrically conductive central portion enclosed in an isolating enclosure;
forming a cover region including a strip overlying the working area between said pair of trenches, wherein said strip includes an electrically conductive layer insulated from the working area by a dielectric layer and a sidewall spacer, wherein the sidewall spacer extends over a side part of each trench of said pair of trenches;
forming a first doped region in the working area of the semiconductor well;
siliciding a part of the electrically conductive central portion;
siliciding the electrically conductive layer;
electrically connecting to the first doped region to provide a first electrode of a filler capacitor cell device; and
electrically connecting to the silicided part of the electrically conductive central portion and the silicided electrically conductive layer to provide a second electrode of the filler capacitor cell device.
21. The method according to claim 20 , further comprising:
forming a second doped region in another portion of the semiconductor well; and
electrically connecting between the second doped region and the first doped region.
22. The method according to claim 20 , further comprising:
forming a doped surface region in the semiconductor well, said doped surface region located between the pair of trenches;
forming a second doped region in a portion of the semiconductor well and in contact with the doped surface region; and
electrically connecting between said first electrical contact and the second doped regions.
23. The method according to claim 20 , further comprising forming a buried doped region in the semiconductor well at a bottom of each trench of said pair of trenches.