Multilayer Wiring Silicide Formation for Sensor Reliability
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Solution Overview
Problem
Existing physical quantity sensors face reliability issues due to voids and cracking caused by excessive silylation, leading to disconnection of wiring and reduced electrical connection reliability.
Innovation Solution
The use of multilayered noble metal and metal films for wiring, with a silicide layer, and an adhesion and insulating layer stack to control thickness and prevent void formation, along with specific materials like Ru, Pt, and SiO2 for improved adhesion and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the wiring in contact with the sensor substrate is increased, then the electrical connection strength is improved, but excessive silylation occurs causing voids and cracking that deteriorate reliability
Solution Approach 1:
The wiring is divided into multiple layers with different thicknesses and materials. The first wiring layer has thickness T1 and the second wiring layer has thickness T2 where T1 < T2. This segmentation allows the thicker second layer to provide strong electrical connection while the thinner first layer minimizes silylation damage and void formation, thus resolving the contradiction between connection strength and reliability.
Solution Approach 2:
The patent uses composite material structure with at least two different metal materials in the wiring layers. This composite approach enables optimization of each layer's properties - the first layer uses material suitable for thin-film formation with good adhesion, while the second layer uses material providing low resistance and strong connection, thereby achieving both strong connection and high reliability.
2Ease of manufacture
If a single-layer thick wiring is used, then manufacturing process is simplified, but voids and cracking occur due to excessive silylation reducing reliability
Solution Approach 1:
Instead of forming a single thick wiring layer, the patent segments the wiring into multiple layers with different thicknesses. The first layer is formed thinner to avoid excessive silylation, and the second layer is formed thicker to ensure low resistance. This segmentation maintains manufacturing feasibility while dramatically improving reliability by preventing void and crack formation.
Solution Approach 2:
The patent transitions from a single-dimensional (single-layer) wiring structure to a multi-dimensional (multi-layer) structure. By adding the vertical dimension with stacked layers of different thicknesses and materials, the solution achieves both ease of manufacture (through standard multi-layer deposition processes) and high reliability (by optimizing each layer's thickness to prevent silylation damage).
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 configuration enhances the reliability of the electrical connection between the sensor substrate and wiring, reducing voids and cracking, ensuring high measurement sensitivity and performance in physical quantity sensors.
Implementation Method 1
a silicide layer is formed by silication
Implementation Method 2
a change in electrostatic capacitance occurring between the fixed electrode and the movable electrode is measured by the change in the gap
Data Source
AI summary
In a physical quantity sensor, wirings provided on a projection and a bonding pad form a silicide layer and are electrically connected. The wirings are multilayered films. A noble metal layer covers the projection and contacts the bonding pad to form the silicide layer. A metal layer extends between the noble metal layer and a base substrate. The metal layer, the noble metal layer, an adhesion layer, and an insulating layer are stacked in this order from the base substrate in all areas except for atop the projection.