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US 7,682,868 B2Granted
Method for making a keyhole opening during the manufacture of a memory cell
AssigneeMacronix International Co., Ltd.
InventorHsiang-Lan Lung
Life of this patent
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Abstract
A keyhole opening is formed during one example of manufacturing a memory cell. An upper layer is formed on a base layer, the base layer having a bottom electrode. The upper layer includes a second layer formed over the base layer and a first layer formed over the second layer. A keyhole opening is formed through the upper layer to expose a surface of the bottom electrode and to create a first memory cell subassembly. The keyhole opening comprises a first, upper opening segment formed within the first layer and a second opening segment formed within the second layer, the first and second opening segments having first and second widths. The first layer has an overhanging portion extending into the opening so that the first width is shorter than the second width.
Claims25
A method for creating a keyhole opening during the manufacture of a memory cell, comprising:
- forming a base layer comprising a bottom electrode;
- selecting a material for a first layer that increases its volume when subjected to a chosen process;
- selecting a material for a second layer that does not increase its volume when subjected to the chosen process;
- forming an upper layer on the base layer, the upper layer forming step comprising forming the second layer over the base layer and the first layer over the second layer;
- forming an opening through the upper layer to expose a surface of the base layer and to create a first memory cell subassembly, the opening comprising a first, upper opening segment formed within the first layer and a second opening segment formed within the second layer, the first and second opening segments having first and second widths;
- and
- subjecting the first memory cell subassembly to the chosen process thereby increasing the volume of the first layer and creating an overhanging portion extending into the opening, the overhanging portion decreasing the size of the first opening segment to create a decreased size, keyhole opening, the first opening segment having a decreased first width, the decreased first width being shorter than the second width by an overhang dimension, the overhang dimension being no more than 10% of the second width.
4 more elements
A method, comprising:
- providing a substrate;
- forming a lower layer of a first material on the substrate;
- forming an upper layer of second material over the lower layer;
- forming an opening through the upper and lower layers to expose a surface of the substrate, the opening comprising an upper opening segment within the upper layer and a lower opening segment within the lower layer, the upper and lower opening segments having respective widths;
- causing expansion of the upper layer by inducing a reaction of the second material with another material creating an overhang extending into the opening, the overhang decreasing the width of the upper opening segment, the decreased width of the upper opening segment being less than the width of the lower opening segment;
- depositing a fill material into the opening using a conformal process creating a void within the deposited material inside the opening;
- and
- anisotropically etching the fill material within the opening to form a more narrow opening exposing the substrate.
5 more elements
A method, comprising:
- providing a substrate;
- forming a lower layer of a first material on the substrate;
- forming an upper layer of second material over the lower layer;
- forming an opening through the upper and lower layers to expose a surface of the substrate, the opening comprising an upper opening segment within the upper layer and a lower opening segment within the lower layer, the upper and lower opening segments having respective widths;
- oxidizing the second material to cause expansion of the upper layer and creating an overhang extending into the opening, the overhang decreasing the width of the upper opening segment, the decreased width of the upper opening segment being less than the width of the lower opening segment;
- depositing a fill material into the opening using a conformal process creating a void within the deposited material inside the opening;
- and
- anisotropically etching the fill material within the opening to form a more narrow opening exposing the substrate.
5 more elements
A method for forming an opening, comprising:
- providing a base layer;
- forming an upper layer on the base layer, the upper layer forming step comprising forming a first layer of a first material over the base layer and a second layer of a second material over the first layer;
- forming an opening through the upper layer to expose a surface of the base layer, the opening comprising an upper opening segment formed within the second layer and a lower opening segment formed within the first layer, the upper and lower opening segments having an initial upper width and an initial lower width;
- and
- increasing the volume of the second layer using a chosen process to create an overhanging portion extending into the opening decreasing the initial upper width, wherein the first material and second material are chosen so that the overhang results from an increase in the volume of the second layer, relative to the first layer, when subjected to the chosen process.
2 more elements
Dependencies are inferred from the claim text.