Methods and apparatuses with vertical strings of memory cells and support circuitry
Apparatuses and methods have been disclosed. One such apparatus includes strings of memory cells formed on a topside of a substrate. Support circuitry is formed on the backside of the substrate and coupled to the strings of memory cells through vertical interconnects in the substrate. The vertical interconnects can be transistors, such as surround substrate transistors and/or surround gate transistors.
1. A method comprising:
forming openings in a substrate;
forming electrically conductive material in the openings;
forming strings of memory cells on a topside of the substrate;
implanting a plurality of wells in a backside of the substrate;
implanting a plurality of diffusion regions, to be associated with support circuitry, in each of the plurality of wells; and
forming support circuitry on the backside of the substrate on the plurality of wells and associated with the plurality of diffusion regions, wherein the support circuitry is coupled to the strings of memory cells through the electrically conductive material formed in the openings.
2. The method of claim 1 , wherein forming the support circuitry comprises using a complementary metal oxide semiconductor (CMOS) fabrication method.
3. The method of claim 1 , wherein forming the support circuitry is performed subsequent to forming the strings of memory cells.
4. An apparatus comprising:
a substrate having an opening;
an electrically insulative material lining the opening;
an electrically conductive material filling the opening lined with the electrically insulative material; and
a diffusion region in a substantially annular pattern around the opening.
5. The apparatus of claim 4 , wherein the opening is open on both sides of the substrate.
6. The apparatus of claim 5 , wherein the diffusion region is a first diffusion region around the opening on a topside of the substrate and further comprising a second diffusion region in a substantially annular pattern around the opening on a backside of the substrate.
7. The apparatus of claim 4 , wherein the diffusion region is a first diffusion region and further comprising:
a second diffusion region implanted in the substrate at a bottom of the opening; and
a metal plug extending from the second diffusion region through the topside of the substrate.
8. The apparatus of claim 4 , wherein the opening comprises an annular ring having a pillar of the substrate in the center of the annular ring and the diffusion region is a first diffusion region around the opening and further comprising a second diffusion region implanted in a top of the pillar.
9. The apparatus of claim 4 , further comprising:
a plurality of strings of memory cells on a first side of the substrate; and
memory support circuitry on a second side of the substrate opposite the first side, wherein the memory support circuitry is coupled to the plurality of strings of memory cells through the electrically conductive material.
10. A method comprising:
forming a plurality of surround gate transistors in a substrate by:
forming openings through the substrate that couple a first side of the substrate to an opposite side of the substrate;
lining the openings with an insulative material; and
forming electrically conductive material in the openings;
forming strings of memory cells on the first side of the substrate; and
forming support circuitry on the opposite of the substrate, wherein the support circuitry is coupled to the strings of memory cells through the surround gate transistors.
11. The method of claim 10 , wherein forming the openings through the substrate comprises:
forming trenches into the first side of the substrate; and
removing a portion of the substrate to reduce a thickness of the substrate such that the trenches couple the first side to the opposite side.
12. The method of claim 11 , further comprising:
forming a source in the electrically conductive material on the first side of the substrate; and
forming a drain in the electrically conductive material on the opposite side of the substrate.
13. The method of claim 12 , wherein the electrically conductive material is a semiconductor material.
14. The method of claim 13 , wherein the drain is doped into the semiconductor material after removal of the portion of the substrate exposes the semiconductor material on the opposite side.
15. The method of claim 11 , further comprising: forming p-wells or n-wells into the substrate on the first side such that the p-wells or n-wells are exposed on the opposite side of the substrate after removal of the portion of the substrate.