Recessed Memory Stack Deposition to Prevent HZO Premature Crystallization
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in forming ferroelectric and anti-ferroelectric films in high aspect ratio structures due to premature crystallization of hafnium zirconium oxide (HZO) layers during atomic layer deposition (ALD), which hinders the achievement of optimal ferroelectric characteristics.
Innovation Solution
The method involves using a sequence of low-temperature ALD processes to form a memory device, where a first electrode layer is deposited within a recessed feature, followed by an amorphous transition metal oxide layer, and then a second electrode layer, all while maintaining the amorphous state of the transition metal oxide layer until an intended annealing step. This approach prevents premature crystallization and allows for controlled crystallization to achieve desired ferroelectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ALD processes are used to deposit transition metal oxide layers, then the deposition process can be completed, but premature crystallization occurs which hinders optimal ferroelectric characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling deposition temperature and performing multiple sequential ALD processes at different temperatures. The transition metal oxide layer is deposited at a first temperature, then a capping layer is deposited at a second temperature, preventing premature crystallization while achieving desired ferroelectric properties through controlled thermal parameters
Solution Approach 2:
The patent applies preliminary action by depositing a capping layer over the transition metal oxide layer before the oxide layer is exposed to conditions that would cause crystallization. This preliminary capping action protects the amorphous state and prevents premature crystallization, allowing subsequent processing steps to be performed without compromising ferroelectric characteristics
2Productivity
If high temperature ALD is used to deposit electrode layers, then deposition speed increases, but the transition metal oxide layer crystallizes prematurely
Solution Approach 1:
The patent applies segmentation by dividing the deposition process into multiple sequential ALD steps with different temperature conditions. Rather than using a single high-temperature process for all layers, the method segments the deposition into stages: depositing the transition metal oxide layer at a first temperature, then depositing the capping layer at a second temperature, allowing each layer to be optimized independently
Solution Approach 2:
The patent applies the intermediary principle by introducing a capping layer as a protective intermediary between the transition metal oxide layer and the high-temperature electrode deposition process. This capping layer acts as a barrier that prevents heat transfer and chemical interaction that would otherwise cause premature crystallization of the oxide layer
3Manufacturing precision
If the substrate temperature is raised above the recrystallization temperature, then the transition metal oxide layer crystallizes, but this prevents control over the crystallographic phase
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the substrate temperature to remain below the recrystallization temperature of the transition metal oxide material. This temperature parameter control allows the amorphous layer to be deposited and maintained in a controllable state, enabling subsequent controlled crystallization to achieve desired ferroelectric or anti-ferroelectric phases
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 method enables the stable and controllable formation of ferroelectric properties in transition metal oxide layers, preventing premature crystallization and allowing for precise engineering of the crystalline structure, which enhances the electrical properties of the memory device.
Implementation Method 1
depositing a first electrode layer within a recessed feature of the substrate using a first atomic layer deposition process
Implementation Method 2
annealing the substrate at a third substrate temperature to crystallize the amorphous transition metal oxide layer and form a crystalline transition metal oxide layer
Implementation Method 3
annealing the substrate at a third substrate temperature to crystallize the amorphous transition metal oxide layer
Data Source
AI summary
A method of forming a memory device on a substrate includes depositing a first electrode layer within a recessed feature of the substrate using a first atomic layer deposition process, and depositing an amorphous transition metal oxide layer over the first electrode layer using a second atomic layer deposition process at a first substrate temperature. And the method further includes, while maintaining an amorphous state of the amorphous transition metal oxide layer, depositing a second electrode layer over the amorphous transition metal oxide layer using a third atomic layer deposition process at a second substrate temperature, the second substrate temperature being lower than a recrystallization temperature of an amorphous transition metal oxide material of the amorphous transition metal oxide layer, and the first electrode layer, the amorphous transition metal oxide layer, and the second electrode layer forming a memory layer stack.