Semiconductor device and method of providing regions of low substrate capacitance
View Patent ↗A semiconductor device ( 2 ) includes a semiconductor substrate ( 12 ) having a surface ( 13 ) formed with a first recessed region ( 20 ). A first dielectric material ( 60 ) is deposited in the first recessed region and formed with a second recessed region ( 76 ), and a second dielectric material ( 100 ) is grown over the first dielectric material to seal the second recessed region.
1. A method of fabricating an integrated circuit, comprising the steps of:
providing a semiconductor substrate having a recessed region;
forming a first dielectric material within the recessed region;
forming a capping layer comprising a semiconductor material overlying the first dielectric material;
forming openings in the capping layer to expose portions of the first dielectric material;
etching the first dielectric material through the openings to form dielectric pillars while leaving portions of the capping layer overlying top surfaces of the dielectric pillars;
growing a second dielectric material to form a seal over the dielectric pillars and voids between the dielectric pillars, wherein the portions of the capping layer are configured to enhance growth of the second dielectc material to form the seal thereby maximizing volume of the voids; and
forming a passive component over the second dielectric material.
2. The method of claim 1 , wherein the step of forming the capping layer comprises forming a polysilicon layer.
3. The method of claim 1 , wherein the step of growing the second dielectric material includes the step of thermally oxidizing the capping layer.
4. The method of claim 1 , wherein the step of forming passive component includes forming a bonding pad.
5. A method of forming a semiconductor device having a region of low substrate capacitance comprising the steps of:
forming a first recessed region in a portion of a semiconductor substrate;
forming a first dielectric layer within the first recessed region;
forming a layer of semiconductor material overlying the first dielectric layer;
forming a plurality of openings in the layer of semiconductor material to expose portions of the first dielectric layer;
removing portions of the first dielectric layer through the plurality of openings to form a plurality of dielectric pillars while leaving portions of the layer of semiconductor material to form a plurality of cap layers overlying top surfaces of the plurality of dielectric pillars; and
thermally oxidizing the plurality of cap layers to form a second dielectric layer that seals voids between adjacent dielectric pillars, wherein the plurality of cap layers is configured to increase volume of each sealed void by minimizing formation of the second dielectric layer on sidewalls of the plurality of dielectric pillars.
6. The method of claim 5 , wherein the step of forming the layer of semiconductor material including forming a polysilicon layer.
7. The method of claim 6 , wherein the step of forming the polysilicon layer includes forming a polysilicon layer having a thickness of about two thousand five hundred angstroms.
8. The method of claim 5 , wherein the step of forming the first dielectric layer within the first recessed region includes forming the first dielectric layer so that an upper surface of the first dielectric layer is recessed below a major surface of the semiconductor substrate.
9. The method of claim 8 , further comprising the step of planarizing the layer of semiconductor material.
10. The method of claim 5 , wherein the step of forming the first dielectric layer includes forming the first dielectric layer having a dielectric constant of about 3.
11. The method of claim 10 , wherein the step of forming the first dielectric layer includes forming the first dielectric layer using chemical vapor deposition.
12. The method of claim 5 , wherein the step of forming the first dielectric layer includes forming a deposited oxide layer using a tetra-ethyl-ortho-silicate source.
13. The method of claim 5 , wherein the step of thermally oxidizing the plurality of cap layers consumes only a portion of each cap layer.
14. The method of claim 5 , further comprising the step of forming a layer of material on sidewalls of the plurality of dielectric pillars, wherein the layer of material is configured to reinforce the plurality of dielectric pillars.
15. The method of claim 14 , wherein the step of forming the layer of material includes forming a layer of amorphous silicon having a thickness of about five hundred angstroms.