Vibrator Electrode Layout for Low-Parasitic Capacitance
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Solution Overview
Problem
The existing vibrator devices suffer from increased parasitic capacitance between the base or lid at ground potential and the electrode of the vibrator element, leading to deterioration of electrical characteristics such as start-up characteristics and output characteristics of oscillation signals.
Innovation Solution
The vibrator device includes a vibrator element, a base, and a lid, where at least one of the base or lid includes a first semiconductor substrate connected to ground potential. The vibrator element has electrodes positioned relative to the semiconductor substrates to minimize parasitic capacitance, with specific constraints on the height of the accommodation space and the distance between the semiconductor substrates and the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base or lid is placed at ground potential to provide a stable reference potential, then the electrical stability is improved, but the parasitic capacitance between the base/lid and the vibrator element electrode increases
Solution Approach 1:
The patent extracts the harmful parasitic capacitance effect by removing the ground potential connection from the base or lid. Instead of grounding the semiconductor substrate, the invention allows it to float electrically, thereby eliminating the capacitive coupling between the grounded base/lid and the vibrator element electrode while maintaining overall electrical stability through alternative means.
Solution Approach 2:
The patent introduces an intermediary insulating film between the base/lid and the vibrator element electrode. This insulating layer acts as a mediator that electrically isolates the semiconductor substrate from direct capacitive coupling with the electrode, thereby reducing parasitic capacitance while maintaining structural integrity and electrical reference stability through other circuit elements.
2Object-generated harmful factors
If the accommodation space height is reduced to minimize parasitic capacitance, then the electrical characteristics are improved, but the device height is reduced which may compromise mechanical stability
Solution Approach 1:
The patent applies local quality by creating an electrically insulating region specifically at the interface between the base/lid and the vibrator element through the insulating film. This localized insulation reduces parasitic capacitance in the critical coupling region without requiring a complete redesign of the overall device structure, thereby maintaining mechanical stability while achieving electrical optimization.
Solution Approach 2:
The patent uses composite material structure by combining the semiconductor substrate (base or lid) with an insulating film layer. This composite structure provides both mechanical support from the semiconductor material and electrical isolation from the insulating film, achieving a balance between mechanical stability and reduced parasitic capacitance.
3Object-generated harmful factors
If the distance between the semiconductor substrate and the first electrode is increased to reduce parasitic capacitance, then the electrical characteristics are improved, but the accommodation space height must increase
Solution Approach 1:
The patent introduces an insulating film as an intermediary layer between the semiconductor substrate and the first electrode. This mediator provides electrical isolation that reduces parasitic capacitance without requiring a large increase in the distance between the substrate and electrode, as the insulating film achieves the electrical isolation function with minimal thickness.
Solution Approach 2:
The patent changes the electrical parameters of the interface region by introducing the insulating film, which has different dielectric properties than air or vacuum. This parameter change (introducing a material with specific permittivity) allows for reduced parasitic capacitance while maintaining a compact accommodation space height, as the capacitance is controlled by the material properties rather than just the geometric distance.
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 reduces parasitic capacitance to 1.0 pF or less, thereby improving the electrical characteristics of the oscillator, including start-up characteristics and output characteristics of oscillation signals, and reducing the height of the vibrator device.
Implementation Method 1
the parasitic capacitance between the first semiconductor substrate and the first electrode is reduced to 1.0 pF or less
Implementation Method 2
an insulating film is provided between the first semiconductor substrate and the first electrode
Data Source
AI summary
A vibrator device includes a vibrator element, a base to which the vibrator element is coupled, and a lid bonded to the base. The vibrator element is accommodated in an accommodation space between the lid and the base. At least one of the base or the lid includes a first semiconductor substrate connected to a ground potential and having a conductivity type that is p-type or n-type. The vibrator element includes a vibrator substrate, a first electrode disposed on a side of the vibrator substrate closer to the first semiconductor substrate, and a second electrode disposed on a side of the vibrator substrate farther from the first semiconductor substrate. L1≤0.2×10−3 and d1≥ε×S1×1012, wherein L1 [m] is the height of the accommodation space, d1 [m] is the distance between the first semiconductor substrate and the first electrode, S1 [m2] is the area of the first electrode, and ε [F/m] is the permittivity of the accommodation space.