Temperature Independent Resistor Using Parallel Thermistors
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Solution Overview
Problem
Semiconductor resistors experience significant resistance variations with temperature changes, making it challenging to maintain a stable resistance value across a broad temperature range without additional processing steps in CMOS manufacturing flows.
Innovation Solution
Combining positive and negative temperature coefficient thermistors in parallel, with specific materials like TiN, TiAlN, silicon, polysilicon, SiGe, or Ge, to control resistance and maintain stability through the use of connecting elements that allow current to flow through both types of thermistors, compensating for their opposite temperature behaviors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single material resistor is used, then the manufacturing process is simple, but the resistance value varies significantly with temperature
Solution Approach 1:
The patent combines a first resistive region with positive temperature coefficient and a second resistive region with negative temperature coefficient into a single resistor structure. These two regions are electrically connected in parallel through connecting elements, allowing their opposing temperature characteristics to compensate each other and achieve substantially temperature-independent resistance behavior.
Solution Approach 2:
The patent uses different materials with opposite temperature coefficients for the two resistive regions. The first resistive region may use TiN or TiAlN (positive temperature coefficient), while the second resistive region may use silicon, polysilicon, SiGe, or Ge (negative temperature coefficient). This composite approach enables temperature compensation without requiring additional processing steps beyond standard CMOS processes.
2Reliability
If temperature compensation is implemented using separate components, then resistance stability is improved, but additional manufacturing steps are required
Solution Approach 1:
The patent integrates the temperature compensation function directly into the resistor structure itself, eliminating the need for separate compensation components. The first and second resistive regions are formed using the same CMOS manufacturing steps that would be used for standard transistor gates, making the temperature compensation feature universal and compatible with existing manufacturing processes without adding steps.
Solution Approach 2:
The patent merges the temperature compensation mechanism with the resistor structure by forming both resistive regions and their connecting elements within the same manufacturing flow. The connecting elements are created using standard via and contact formation steps, and the resistive regions are deposited using standard gate electrode deposition techniques, thereby integrating compensation functionality without additional process steps.
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
Achieves a substantially stable resistance value over a predetermined temperature range, from -50°C to +100°C, without requiring additional steps beyond standard CMOS processes, by finely tuning the current flow through the thermistors to cancel out their temperature-dependent resistances.
Implementation Method 1
a material may experience a so-called positive temperature coefficient type of resistance, in which the resistance increases with the increase of the temperature
Implementation Method 2
or a negative temperature coefficient type of resistance, in which the resistance decreases when the temperature increases
Data Source
AI summary
The present disclosure relates to a semiconductor structure comprising a positive temperature coefficient thermistor and a negative temperature coefficient thermistor, connected to each other in parallel by means of connecting elements which are configured such that the resistance resulting from the parallel connection is substantially stable in a predetermined temperature range, and to a corresponding manufacturing method.