3-D planes memory device
View Patent ↗The present invention is a means and a method for manufacturing large three dimensional memory arrays. The present invention is a means and a method for addressing the WL and BL resistance by creating arrays having not only large plane conductors for each of the memory layers (WLs) but also for the opposite polarity common layer (BL). The present invention is also a means and a method to form via interconnections between the substrate logic and the respective layers of a multidimensional array. The present invention is also a way to operate an array in which the select device is unipolar but the array is above to be operated in a bipolar way. This facilitates a bipolar operation for memory cell technologies such as Resistive RAM (e.g., RRAM, ReRAM and Memresistors).
1. A method for making connections between a plurality of layers and a layer below the plurality of layers comprising the steps of
(i) creating a plurality of vertical interconnects and a polymer ramp, wherein the polymer ramp is disposed over the plurality of vertical interconnects,
(ii) selectively etching back the vertical interconnects such that a vertical interconnect is proximate to or below one or more layers of the plurality of layers, wherein the selectively etching back comprises:
etching the polymer ramp and exposing conductive material of the plurality of vertical interconnects; and
etching the exposed conductive material, wherein exposed conductive material that is disposed under a thin area of the polymer ramp are etched for a longer time than exposed conductive material that is disposed under a thicker area of the polymer ramp, and
(iii) connecting a vertical interconnect to a proximate layer, whereby each layer is electrically connected to the layer below the plurality of layers by at least one vertical interconnect.
2. The method of claim 1 whereby the layer below the plurality of layers comprises circuitry.
3. The method of claim 1 wherein the polymer ramp has a plurality of differing heights.
4. The method of claim 3 further comprising
(i) applying a malleable material above the plurality of vertical interconnects, and
(ii) applying a feature into the malleable material to form the polymer ramp.
5. The method of claim 4 , whereby applying a feature comprises one or more of the steps of
(i) applying a malleable material to the surface above the plurality of vertical interconnects and then applying a feature into the malleable material, and
(ii) applying a malleable material to a surface feature and transferring the malleable material to an area above the plurality of vertical interconnects.
6. The method of claim 5 whereby applying a malleable material comprises one or more of pouring, dripping, spraying and spinning.
7. The method of claim 3 comprising the use of imprint lithography.
8. The method of claim 3 further comprising etching both the feature comprising a slope or stair-step or plurality of differing heights and the plurality of vertical interconnects such that the amount of etching of a vertical interconnect is related to the height of the feature comprising a slope or stair-step or plurality of differing heights above that vertical interconnect.