Acoustic Wave Device and Varactor Integration on Compound Semiconductor
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Solution Overview
Problem
Conventional acoustic wave devices on silicon substrates face challenges such as high production costs due to expensive and time-consuming chemical mechanical polishing, and design limitations that lead to signal loss and mechanical stress issues, with no integration with compound semiconductor power amplifiers on the same substrate.
Innovation Solution
An integrated structure of acoustic wave devices and varactors on a compound semiconductor epitaxial substrate, featuring a semiconductor substrate with a bottom epitaxial structure and acoustic wave device upper structure, which includes a protection layer and resonance structure to widen the gap and prevent mechanical stress, optimizing impedance matching and reducing signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing (CMP) is used to remove the phosphosilicate glass layer, then the surface roughness is improved, but the production cost and time consumption increase significantly
Solution Approach 1:
The patent extracts and removes the phosphosilicate glass layer through selective etching processes instead of using CMP. The etching selectively removes the PSG layer while leaving the underlying structure intact, achieving the desired surface preparation without the need for expensive and time-consuming mechanical polishing operations.
2Device complexity
If a single recess design is used, then the structure is simple, but the gap between the acoustic wave device bottom and recess bottom cannot be widened, causing mechanical stress issues
Solution Approach 1:
The patent divides the single recess structure into multiple recesses (first recess and second recess). This segmentation allows the acoustic wave device to be supported at multiple points, creating sufficient gap between the device bottom and recess bottoms to prevent mechanical stress and bending while maintaining structural integrity.
3Adaptability or versatility
If acoustic wave devices and power amplifiers are fabricated on separate substrates, then each component can be optimized independently, but the component size increases and signal loss occurs
Solution Approach 1:
The patent merges the acoustic wave device and power amplifier fabrication onto a single compound semiconductor epitaxial substrate. This integration reduces the overall component size, minimizes the distance between components to reduce signal loss, and maintains the ability to independently optimize each component's structure and performance characteristics.
Data Source
AI summary
An integrated structure of acoustic wave device and varactor comprises an acoustic wave device and a varactor formed on a first part and a second part of a semiconductor substrate respectively. The acoustic wave device comprises an acoustic wave device upper structure and a first part of a bottom epitaxial structure. The acoustic wave device upper structure is formed on the first part of the bottom epitaxial structure. The varactor comprises a varactor upper structure and a second part of the bottom epitaxial structure. The varactor upper structure is formed on the second part of the bottom epitaxial structure. The integrated structure of the acoustic wave device and the varactor formed on the same semiconductor substrate is capable of reducing the module size, optimizing the impedance matching, and reducing the signal loss between the varactor and the acoustic wave device.