RF Semiconductor Substrate Backside Processing for Low Leakage
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Solution Overview
Problem
Radio frequency devices face challenges in achieving reduced insertion loss and improved linearity due to increased leakage currents and inhomogeneous voltage distribution caused by substrate thinning, which affects their performance in high-frequency applications like 5G communication.
Innovation Solution
A method involving the thinning of a semiconductor substrate from one side and processing the opposite side to form a processed region with ion implanted, doped, or etched layers to reduce leakage currents and enhance radio frequency linearity, while optionally forming a heat spreader layer and using a support substrate with a lower dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the semiconductor substrate is thinned from the second side, then the insertion loss is reduced and radio frequency performance is improved, but leakage currents increase and radio frequency linearity deteriorates
Solution Approach 1:
The patent applies local quality by creating a processed region with different properties (ion implanted, doped, or etched) at the second side of the substrate, specifically in areas where leakage currents occur. This localized processing modifies the electrical properties in specific regions without affecting the entire substrate, thereby reducing leakage currents while maintaining the overall thin substrate structure that provides low insertion loss.
Solution Approach 2:
The patent changes physical parameters of the substrate by thinning it from the second side to reduce parasitic capacitances and improve radio frequency performance. Additionally, further parameter changes are made through ion implantation, doping, or etching processes that modify the electrical characteristics of the processed region, transforming the substrate from a uniform structure to one with spatially varying properties that simultaneously achieve low insertion loss and high linearity.
2Speed
If the semiconductor substrate is thinned from the second side, then the device performance in high-frequency applications is improved, but inhomogeneous voltage distribution occurs
Solution Approach 1:
The processed region is created with locally modified properties to compensate for the inhomogeneous voltage distribution that arises from substrate thinning. By applying ion implantation, doping, or etching in specific areas, the patent creates regions with different electrical characteristics that balance out the voltage distribution issues, allowing the thin substrate to maintain both high-frequency performance and voltage stability.
3Reliability
If the second side of the substrate is processed to reduce leakage currents, then radio frequency linearity is improved, but the device complexity increases
Solution Approach 1:
The patent extracts or removes material from the second side of the substrate through etching processes to create the processed region. This removal of material serves multiple functions: it reduces leakage currents, modifies electrical properties, and can create necessary structural features. By taking out material rather than adding complex structures, the patent achieves improved radio frequency linearity while relatively limiting the increase in device complexity.
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 significantly reduces leakage currents and improves radio frequency linearity, mitigating adverse effects of substrate thinning and enabling better performance in high-frequency applications by reducing substrate capacitances and enhancing device reliability.
Implementation Method 1
a processed region at the second side of the semiconductor substrate, wherein the processed region comprises one or more of: an ion implanted layer
Implementation Method 2
thinning the semiconductor substrate from the second side... significantly reduces leakage currents and improves radio frequency linearity, mitigating adverse effects of substrate thinning by reducing substrate capacitances
Data Source
AI summary
A device includes a thinned semiconductor substrate having a first side and a second side opposite to the first side; and at least one radio frequency device at the first side, wherein the second side of the thinned semiconductor substrate is processed to reduce leakage currents or to improve a radio frequency linearity of the at least one radio frequency device through Bosch etching.