Resistance Variable Film Formation via Segmented Deposition
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Solution Overview
Problem
Existing methods for forming resistance variable memory devices face challenges in efficiently creating a resistance variable film with a crystalline region surrounded by an amorphous region, which is crucial for optimal performance, due to issues with filling openings in insulating films and maintaining desired elemental concentrations.
Innovation Solution
A method involving the formation of a resistance variable film with a specific elemental composition, including a first element with a high heat of vaporization, a chalcogen element, and a second element, where the concentration of the first element is lower in the crystalline region and higher in the amorphous region, using a physical vapor deposition process to achieve the desired structural and compositional characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resistance variable film is formed to fill an opening in an insulating film, then the opening is filled with the resistance variable material, but it is difficult to maintain desired elemental concentrations and achieve proper crystalline/amorphous region distribution
Solution Approach 1:
The resistance variable film formation process is segmented into multiple deposition steps, where different element layers are deposited sequentially. This allows precise control over elemental concentrations in different regions (crystalline vs amorphous) by adjusting deposition parameters for each layer, resolving the contradiction between manufacturing precision and process complexity.
Solution Approach 2:
The patent creates different elemental compositions in different regions of the resistance variable film. The crystalline region has a specific Ge2Sb2Te5 stoichiometry while the amorphous region has different elemental concentrations. This local quality variation is achieved through controlled deposition and thermal processing, enabling precise control of resistance characteristics in different spatial zones.
2Reliability
If the resistance variable film is deposited to completely fill the opening, then voids are eliminated, but achieving the desired crystalline region surrounded by amorphous region becomes more difficult
Solution Approach 1:
The patent performs preliminary deposition of the resistance variable film material before final thermal processing. The film is deposited with controlled thickness and composition, then subsequent thermal annealing creates the crystalline/amorphous region structure. This preliminary action ensures complete filling without voids while setting up the conditions for proper phase formation.
Solution Approach 2:
The patent utilizes phase transitions during thermal processing to create the desired structure. The deposited amorphous film undergoes partial crystallization during annealing, forming crystalline regions surrounded by remaining amorphous material. This phase transition approach eliminates voids through proper filling while simultaneously creating the required crystalline/amorphous morphology.
3Manufacturing precision
If elements with different heats of vaporization are used in the resistance variable film, then elemental distribution can be controlled, but maintaining stoichiometry becomes more challenging
Solution Approach 1:
The patent exploits differences in vaporization parameters (heats of vaporization) of different elements during deposition and thermal processing. Elements with higher heats of vaporization (Ge, Sb) behave differently from those with lower heats (Te) during annealing, enabling controlled segregation and distribution. This parameter-based control achieves desired elemental distribution while maintaining overall stoichiometry through optimized processing conditions.
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 allows for the effective formation of a resistance variable memory device with improved filling characteristics and elemental distribution, enhancing the device's performance and reliability by creating a crystalline region with a Ge2Sb2Te5 structure and maintaining appropriate elemental concentrations.
Implementation Method 1
a physical vapor deposition process to achieve the desired structural and compositional characteristics
Implementation Method 2
colliding ions of the plasma with the target to separate the deposition source material from the target
Implementation Method 3
the heater may have a temperature of about 260° C. to about 350° C.
Implementation Method 4
creating a crystalline region with a Ge2Sb2Te5 structure
Data Source
AI summary
A method of forming a resistance variable memory device, the method including forming a diode on a semiconductor substrate; forming a lower electrode on the diode; forming a first insulating film on the lower electrode, the first insulating film having an opening; forming a resistance variable film filling the opening such that the resistance variable film includes an amorphous region adjacent to a sidewall of the opening and a crystalline region adjacent to the lower electrode; and forming an upper electrode on the resistance variable film.