Ge(II) Source Low-Temperature Phase Change Material Deposition
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Solution Overview
Problem
Existing methods for forming phase change material layers in phase change memory devices require high temperatures and have limitations in achieving conformal deposition with small grain sizes, which can lead to voids and poor step coverage.
Innovation Solution
A method involving the use of a Ge(II) source, along with specific reaction gases and sources like Te and Sb, is employed to form a Ge-containing phase change material layer at reduced temperatures, utilizing chemical vapor deposition or atomic layer deposition, which improves reactivity and reduces steric hindrance, allowing for conformal deposition with smaller grain sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature deposition is used to form phase change material layers, then the material can be deposited, but the grain size becomes large and voids occur, reducing manufacturing precision
Solution Approach 1:
The patent changes the chemical parameters of the deposition process by using Ge(II) source instead of conventional Ge(IV) source, and employs specific reaction gases (H2S, PH3, AsH3, SbH3) to enable low-temperature deposition below 300°C. This parameter change allows conformal deposition with small grain sizes without requiring high temperatures, thereby improving manufacturing precision while reducing temperature.
Solution Approach 2:
The patent forms composite phase change material layers containing Ge, S, P, As, and/or Sb elements through simultaneous or sequential deposition of multiple sources. This composite approach creates materials with optimized properties that enable low-temperature processing while maintaining small grain sizes and preventing void formation, thus resolving the contradiction between temperature and deposition quality.
2Manufacturing precision
If conventional Ge(IV) source is used for deposition, then the process is simpler, but steric hindrance prevents conformal deposition in small features
Solution Approach 1:
The patent uses Ge(II) source which has different chemical properties and reduced steric hindrance compared to Ge(IV) source, enabling the deposition process to achieve uniform coverage in localized small features such as contact holes and trenches. The Ge(II) source molecules are smaller and more reactive, allowing them to access and conformally coat narrow structures that would be inaccessible to larger Ge(IV) source molecules.
3Manufacturing precision
If high temperature processing is applied, then deposition occurs, but grain growth leads to void formation and poor film quality
Solution Approach 1:
The patent fundamentally changes the deposition temperature parameter from conventional high temperatures (>300°C) to low temperatures (<300°C, specifically 200-250°C in some embodiments). This temperature reduction prevents excessive grain growth and void formation while maintaining film uniformity through the use of Ge(II) source and controlled reaction conditions with specific reaction gases.
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
The method enables the formation of phase change material layers at temperatures below 300°C, specifically 200°C, with improved step coverage and smaller grain sizes, preventing voids and enhancing the conformality on contact holes or trenches.
Implementation Method 1
forming a Ge-containing phase change material layer on the lower electrode by supplying a reaction gas including the composition of Formula 1, a first source including Ge(II), and a second source into the reaction chamber
Implementation Method 2
utilizing chemical vapor deposition or atomic layer deposition, which improves reactivity and reduces steric hindrance, allowing for conformal deposition with smaller grain sizes
Implementation Method 3
As a write current flows through the lower electrode and the switching device of the unit memory cell, joule heat is generated at a boundary surface between the lower electrode and the phase change material film
Data Source
AI summary
In one aspect, a method of forming a phase change material layer is provided. The method includes supplying a reaction gas including the composition of Formula 1 into a reaction chamber, supplying a first source which includes Ge(II) into the reaction chamber, and supplying a second source into the reaction chamber. Formula 1 is NR1R2R3, where R1, R2 and R3 are each independently at least one selected from the group consisting of H, CH3, C2H5, C3H7, C4H9, Si(CH3)3, NH2, NH(CH3), N(CH3)2, NH(C2H5) and N(C2H5)2.