Silicon Carbide Substrate Warpage Control via Nitrogen Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon carbide substrates often warp due to differences in lattice constants and stress between their carbon-side and silicon-side principal surfaces, particularly when the diameter exceeds 100 mm, leading to issues in photolithography processes.
Innovation Solution
A silicon carbide substrate with a 4H crystal structure and a nitrogen concentration gradient, where the carbon-side principal surface has a higher nitrogen concentration than the silicon-side, reducing the difference in Raman peak shifts to less than 0.2 cm−1, thereby minimizing tensile and compressive stresses and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the silicon carbide substrate is increased to 100 mm or greater, then the productivity and device performance are improved, but warpage occurs due to stress differences between the carbon-side and silicon-side principal surfaces
Solution Approach 1:
The patent applies local quality by creating a nitrogen concentration gradient where the nitrogen concentration differs between the carbon-side principal surface and the silicon-side principal surface. Specifically, the nitrogen concentration at the carbon-side surface is controlled to be within 1×10^18 to 1×10^20 atoms/cm³, while the nitrogen concentration at the silicon-side surface is controlled to be within 1×10^18 to 1×10^19 atoms/cm³. This localized variation in nitrogen distribution compensates for the inherent stress differences between the two surfaces, thereby reducing warpage in large-diameter substrates without affecting the overall substrate size or productivity.
2Shape
If the nitrogen concentration is increased to reduce warpage, then the stress balance is improved, but the manufacturing precision and control difficulty increase
Solution Approach 1:
The patent applies parameter changes by establishing specific numerical ranges for nitrogen concentration at different surfaces. The nitrogen concentration at the carbon-side principal surface is controlled to be within 1×10^18 to 1×10^20 atoms/cm³, and at the silicon-side principal surface within 1×10^18 to 1×10^19 atoms/cm³. These quantified parameters provide clear manufacturing targets and acceptance criteria, making the control process more manageable and precise while effectively reducing warpage.
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 substrate effectively reduces warpage by managing stress through a controlled nitrogen concentration gradient, ensuring reliable performance in semiconductor device manufacturing.
Implementation Method 1
a difference between a Raman peak shift of the carbon-side principal surface and a Raman peak shift of the silicon-side principal surface is smaller than or equal to 0.2 cm−1
Data Source
AI summary
A silicon carbide substrate includes a carbon-surface-side principal surface and a silicon-surface-side principal surface. The silicon carbide substrate has a diameter of 100 mm or greater and a thickness of 300 μm or greater. An off angle of the carbon-surface-side principal surface and the silicon-surface-side principal surface relative to a {0001} plane is smaller than or equal to 4°. A nitrogen concentration in the carbon-surface-side principal surface is higher than a nitrogen concentration in the silicon-surface-side principal surface, and a difference in Raman peak shift between the carbon-surface-side principal surface and the silicon-surface-side principal surface is smaller than or equal to 0.2 cm−1.