Via-less Thin Film Resistor with Dielectric Cap
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Solution Overview
Problem
Conventional precision resistors in integrated circuits face challenges with size constraints, temperature coefficient variations, and vertical space requirements, limiting the miniaturization and precision of electronic devices due to the need for additional circuitry and substrate area for resistance stabilization.
Innovation Solution
A method for forming a thin film resistor that laterally connects adjacent interconnect structures using a resistive layer with a dielectric cap, reducing the need for vias and resistor head contact structures, and allowing for precise resistance control with a low temperature coefficient, thereby minimizing space and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional precision resistors with vias and resistor head contact structures are used, then electrical connection between conductive layers is achieved, but vertical space requirements increase and device miniaturization is limited
Solution Approach 1:
The invention removes the via structures and resistor head contact structures from the conventional precision resistor design. By laterally connecting the resistive layer directly between adjacent interconnect structures, the vertical connection path through dielectric layers is eliminated, thereby reducing vertical space requirements and structural complexity.
Solution Approach 2:
The invention transitions from a vertical connection architecture to a lateral connection architecture. Instead of connecting conductive layers through vertical vias through multiple dielectric layers, the resistive layer is formed to laterally connect between adjacent interconnect structures on the same or adjacent planes, fundamentally changing the dimensional approach to electrical connection.
2Reliability
If additional circuitry is included adjacent to the resistor for resistance stabilization, then temperature coefficient variations are compensated, but substrate area increases
Solution Approach 1:
The invention merges the resistor function with the interconnect structures by laterally connecting the resistive layer directly between adjacent interconnect structures. This integration eliminates the need for separate stabilization circuitry, as the resistive layer itself is formed within the interconnect framework, thereby maintaining resistance stability without increasing substrate area.
Solution Approach 2:
The resistive layer serves multiple functions simultaneously: it provides the precision resistance value, it is laterally connected to interconnect structures for electrical connection, and it is protected by the dielectric cap layer. This multi-functionality eliminates the need for additional dedicated stabilization circuitry, reducing overall substrate area while maintaining reliability.
3Manufacturing precision
If laser trimming is used to increase resistance precision, then resistance tolerance is improved, but substrate area and device complexity increase
Solution Approach 1:
The invention achieves resistance precision through controlled deposition parameters of the resistive layer rather than post-fabrication laser trimming. By adjusting deposition conditions, thickness, and composition during the sputtering or evaporation process, the desired resistance value and tolerance are obtained directly, eliminating the need for laser trimming and associated substrate area requirements.
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 enables the creation of thermally stable, high-precision thin film resistors with reduced size and material usage, improving the integration of resistors into compact electronic devices while maintaining precise resistance values and stability.
Implementation Method 1
A thin film resistor layer is generally evaporated or sputtered on the substrate 20
Implementation Method 2
A third dielectric layer 32 is formed overlying the precision resistor 12
Data Source
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AI summary
The present disclosure is directed to a thin film resistor structure (100) that includes a resistive element (102) electrically connecting first conductor layers (106a,b) of adjacent interconnect structures (104a,b). The resistive element is covered by a dielectric cap layer (105) that acts as a stabilizer and heat sink for the resistive element. Each interconnect includes a second conductor layer (124) over the first conductive layer. The thin film resistor includes a chromium silicon resistive element covered by a silicon nitride cap layer.