Silicon Nitride Substrate Composition for Heat and Dielectric Stability
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Solution Overview
Problem
Existing silicon nitride sintered compacts face challenges in maintaining high thermal conductivity while suppressing polarization and ensuring stable dielectric properties, particularly at higher operating frequencies of semiconductor elements.
Innovation Solution
Incorporating a grain boundary phase with a specific atom ratio of Mg to rare-earth elements (Mg/RE) within the range of 0.01 to 1.5, along with controlled distribution and composition of REMgSi2O5N crystals, to enhance thermal conductivity and stabilize dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermal conductivity of silicon nitride sintered compact is increased to exceed 100 W/m·K, then the heat dissipation performance is improved, but the dielectric properties and polarization stability may deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atom ratio of Mg to rare-earth elements (RE) in the grain boundary phase within the range of 0.01 to 1.5. This specific compositional parameter control enables the material to achieve thermal conductivity exceeding 100 W/m·K while maintaining stable dielectric properties with relative dielectric constant below 9.0 at 10 MHz, resolving the contradiction between thermal conductivity improvement and dielectric stability.
Solution Approach 2:
The patent utilizes composite materials by incorporating a grain boundary phase containing both Mg and rare-earth elements (such as Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) into the silicon nitride matrix. This composite grain boundary phase structure enables simultaneous achievement of high thermal conductivity (>100 W/m·K) and stable dielectric properties, overcoming the trade-off between thermal performance and electrical insulation.
2Speed
If the operating frequency of semiconductor elements is increased to enhance performance, then the processing speed and efficiency are improved, but the heat generation amount increases causing thermal management issues
Solution Approach 1:
The patent applies parameter changes by optimizing the Mg/RE atom ratio in the grain boundary phase to achieve high thermal conductivity exceeding 100 W/m·K. This enables effective heat dissipation from high-frequency semiconductor devices operating at 1 MHz and above, preventing thermal accumulation while maintaining high-speed operation.
3Reliability
If the relative dielectric constant at high frequency is reduced to below 9.0 at 10 MHz, then the insulative properties are improved, but the thermal conductivity may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Mg/RE atom ratio within 0.01 to 1.5 and selecting specific rare-earth elements to achieve a relative dielectric constant below 9.0 at 10 MHz while simultaneously maintaining thermal conductivity exceeding 100 W/m·K, resolving the contradiction between insulative properties and thermal conductivity.
Solution Approach 2:
The patent utilizes composite materials by incorporating a dual-element grain boundary phase (Mg + rare-earth elements) that provides both low dielectric constant at high frequency and high thermal conductivity, enabling the silicon nitride sintered compact to achieve superior combined electrical and thermal performance.
4Reliability
If the frequency dependence of relative dielectric constant is improved to reduce polarization, then the dielectric stability is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by defining a specific Mg/RE atom ratio range (0.01 to 1.5) that naturally achieves improved frequency dependence of dielectric constant with (εr50−εr1000)/εr50≤0.1, reducing polarization effects. While the composition control requires precision, the clear parameter specification enables systematic manufacturing with quality control.
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
The solution achieves thermal conductivity exceeding 100 W/m·K and relative dielectric constants below 9.0 at 10 MHz, with minimal frequency and temperature dependence, ensuring high reliability and insulative properties for semiconductor devices.
Implementation Method 1
The thermal conductivity of the silicon nitride sintered compact is not less than 100 W/m·K
Implementation Method 2
A relative dielectric constant ε10M-25 at 10 MHz and room temperature is not more than 9.0. Improving the frequency dependence of the relative dielectric constant makes it difficult for polarization of the silicon nitride substrate to occur.
Data Source
AI summary
Provided is a highly heat-conductive silicon nitride sintered compact capable of achieving the improvement in both of a heat conductivity and a relative permittivity. The highly thermally-conductive silicon nitride sintered compact according to an embodiment includes silicon nitride crystal grains and a grain boundary phase. The thermal conductivity of the silicon nitride sintered compact is not less than 100 W/m·K. A grain boundary phase present in a 5 μm×5 μm measurement area in any cross section includes Mg and a rare-earth element (RE). The atom ratio of Mg to rare-earth element is within the range of not less than 0.01 and not more than 1.5. A relative dielectric constant ε10M-25 at 10 MHz and room temperature is not more than 9.0.