Phase Change Resistor TCR Trimming via Ge2Sb2Te5
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing resistor structures for integrated circuits face challenges in achieving precise resistance values and zero temperature coefficient of resistance (TCR), requiring complex manufacturing processes and multiple materials, which increases costs and complexity.
Innovation Solution
A resistor structure utilizing phase change materials, such as Ge2Sb2Te5, is developed, where the resistive region comprises areas with different crystalline phases, allowing for trimming of resistance and TCR by controlling the phase transitions through thermal or laser processes, enabling precise resistance values and approximately zero TCR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If series- or parallel-coupled resistors of different materials with different TCRs are used to obtain zero TCR, then the temperature coefficient of resistance is reduced to almost zero, but the device complexity and manufacturing cost increase due to requiring multiple masks, various materials, and multiple interconnection levels
Solution Approach 1:
The patent changes the physical state parameter of the phase change material through thermal processing. By heating the material to different temperatures, the resistivity and TCR are adjusted: at lower temperatures the material exhibits one TCR value, while at higher temperatures it transitions to exhibit a different TCR value, enabling trimming without additional structures
Solution Approach 2:
The patent utilizes phase transitions of the phase change material (such as Ge2Sb2Te5) to achieve TCR trimming. The material transitions between different crystalline phases or structural states through controlled heating, which fundamentally changes its electrical properties including resistivity and temperature coefficient, allowing a single resistor to exhibit multiple TCR characteristics
2Manufacturing precision
If high resistivity materials are used to achieve good resistor performance, then the resistance value is improved, but the temperature coefficient of resistivity increases to about 100 ppm/°C
Solution Approach 1:
The patent changes the physical state parameter of the phase change material through thermal processing. By heating the material to different temperatures, the resistivity and TCR are adjusted: at lower temperatures the material exhibits one TCR value, while at higher temperatures it transitions to exhibit a different TCR value, enabling trimming without additional structures
Solution Approach 2:
The patent uses phase change materials such as Ge2Sb2Te5 that combine properties of different materials. These materials exhibit metallic behavior at certain temperatures with low TCR and semiconducting behavior at other temperatures with high TCR, effectively creating a temperature-dependent composite behavior within a single material layer
3Manufacturing precision
If physically removing portions of the resistor via laser trimming is performed to obtain accurate resistance values, then the resistance precision is improved, but the manufacturing time and process complexity increase
Solution Approach 1:
The patent changes the physical state parameter of the phase change material through thermal processing. By heating the material to different temperatures, the resistivity and TCR are adjusted: at lower temperatures the material exhibits one TCR value, while at higher temperatures it transitions to exhibit a different TCR value, enabling trimming without additional structures
Solution Approach 2:
The patent replaces the mechanical laser trimming process with a thermal field-based phase transition process. Instead of physically removing material with a laser beam, the invention uses controlled heating to induce phase transitions that modify the electrical properties in situ, eliminating material removal and reducing processing time
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 simplifies the manufacturing process, reduces costs, and allows for reversible trimming of resistance and TCR, achieving precise resistance values and minimizing thermal drift, while being compatible with various substrates including flexible ones.
Implementation Method 1
the resistive region comprises at least two areas having different crystalline phases
Implementation Method 2
carried out via laser while verifying the electrical characteristics
Implementation Method 3
controlling the phase transitions through thermal or laser processes
Implementation Method 4
positive TCRs and negative TCRs matched together so that the effective temperature coefficient is almost zero
Data Source
AI summary
An embodiment of a resistor formed by at least one first portion and one second portion, electrically coupled to one another and with different crystalline phases. The first portion has a positive temperature coefficient, and the second portion has a negative temperature coefficient. The first portion has a first resistivity, and the second portion has a second resistivity, and the portions are coupled so that the resistor has an overall temperature coefficient that is approximately zero.