PCRAM Memory Manufacturing via Sacrificial Dielectric Etching
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Solution Overview
Problem
Existing PCRAM memory structures face challenges in precisely controlling the active surface of memory cells, leading to varying performance and high electrical consumption due to limitations in photolithography and spacer formation techniques.
Innovation Solution
A manufacturing process involving the formation of rectilinear trenches, deposition of active layers, and anisotropic etching of sacrificial dielectric material to define the active surface, allowing for precise control of the contact area between phase change material and electrodes, thereby reducing programming current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography and spacer formation techniques are used to define the active surface, then the manufacturing process is relatively simple, but the dimensional control precision is insufficient leading to performance variations
Solution Approach 1:
The patent introduces a sacrificial dielectric material as an intermediary element that enables precise definition of the active surface. This sacrificial material is deposited between the lower and upper electrodes, allowing the active surface boundaries to be precisely controlled through its lateral etching. The sacrificial material acts as a temporary structure that mediates the formation of the active surface, which is then revealed after selective removal. This approach achieves superior dimensional control compared to direct photolithography methods while maintaining manufacturing feasibility.
2Use of energy by moving object
If the active surface area is reduced to lower programming current, then energy consumption decreases, but manufacturing precision requirements increase
Solution Approach 1:
The sacrificial dielectric material serves as a precise template that defines the active surface area. By controlling the dimensions and position of this sacrificial material, the active surface can be precisely reduced to minimize programming current while maintaining uniformity across all memory cells. The sacrificial material's lateral etching creates well-defined boundaries that ensure consistent small active surface areas, thereby achieving low energy consumption with high manufacturing precision.
Solution Approach 2:
The sacrificial dielectric material is deposited and positioned in advance before the upper electrode is formed. This preliminary action establishes the precise boundaries of the active surface before subsequent manufacturing steps. By pre-defining the active surface area through the sacrificial material, the method ensures that the final active surface dimensions are controlled with high precision, enabling reduced programming current while maintaining manufacturing feasibility.
3Manufacturing precision
If the active surface is precisely defined using sacrificial dielectric material and lateral etching, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The sacrificial dielectric material acts as a temporary intermediary structure that simplifies the overall manufacturing process despite adding a deposition step. It provides a straightforward method to define active surface boundaries through lateral etching, which is a standard semiconductor manufacturing technique. The sacrificial material is later removed, leaving the precisely defined active surface. This intermediary approach achieves high manufacturing precision using conventional process steps, balancing complexity and precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise dimensional control of the active surface, reducing disparities in cell performance and lowering programming current, resulting in improved electrical contact quality and reduced energy consumption.
Implementation Method 1
A phase change material is able to switch very quickly and reversibly between an amorphous phase and a crystalline phase
Implementation Method 2
The transition from the crystalline state to the amorphous state is obtained by applying a short current pulse of high amplitude, to locally melt the crystalline material
Implementation Method 3
performing an anisotropic etching of the sacrificial dielectric material so as to expose a side surface of each portion of the first active layer
Data Source
Figure 1~2
Figure 3~4B
Figure 4C~4E
AI summary
The invention relates to a method for manufacturing a PCRAM memory comprising the following steps: - providing a substrate comprising lower electrodes; - forming in a first dielectric layer disposed on the substrate a first straight trench opening at least partially onto the set of lower electrodes; - depositing a first active layer in the first straight trench, such that the first active layer is in electrical contact with the lower electrodes; - covering the first active layer with a second dielectric layer; - etching in the second dielectric layer, the first active layer and the first dielectric layer, additional straight trenches oriented perpendicular to the first trench, so as to obtain a group of memory devices each comprising a portion of the first active layer in electrical contact with one of the lower electrodes;- fill the additional straight trenches with a sacrificial dielectric material; - perform an anisotropic etching of the sacrificial dielectric material so as to expose a lateral surface of each portion of the first active layer; and - cover the lateral surface of each portion of the first active layer with a second active layer.