Gettering Layer for Oxygen Removal in Silicon Substrate
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Solution Overview
Problem
Reducing oxygen concentration in silicon wafers during production is complex and costly, and existing methods struggle to maintain consistent device characteristics with high dissolved oxygen levels.
Innovation Solution
A semiconductor device manufacturing method involving the formation of a gettering layer on a silicon substrate to capture dissolved oxygen and residual metals, followed by heat treatment and removal of the layer, ensuring consistent device characteristics despite high oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxygen concentration of silicon wafer is reduced during production, then device characteristics become more stable, but production complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by forming a gettering layer on the silicon wafer surface before device fabrication. This layer is designed to capture and remove oxygen and metal impurities during subsequent heat treatment processes, thereby pre-conditioning the wafer to achieve stable device characteristics without requiring complex oxygen reduction during wafer production
Solution Approach 2:
The gettering layer acts as an intermediary substance between the silicon wafer and the harmful oxygen/metal impurities. During heat treatment, this intermediate layer absorbs and traps the impurities that would otherwise diffuse into the device regions, enabling stable device characteristics while maintaining simple production processes
2Manufacturing precision
If dissolved oxygen is removed from silicon substrate, then resistivity stability improves, but manufacturing cost increases
Solution Approach 1:
The patent extracts harmful dissolved oxygen and metal impurities from the silicon substrate by introducing a gettering layer that selectively captures these impurities during heat treatment. This extraction process occurs in-situ during standard manufacturing heat cycles, achieving resistivity stability without adding costly separate removal steps
Solution Approach 2:
The patent utilizes parameter changes by controlling the heat treatment temperature and duration to optimize the gettering effect. By adjusting these thermal parameters, the gettering layer effectively captures oxygen and metals at standard manufacturing costs, achieving resistivity stability through optimized process parameters rather than expensive material removal
3Temperature
If heat treatment is performed at low temperature, then thermal donors form from dissolved oxygen, but device characteristics deteriorate
Solution Approach 1:
The patent converts the harmful effect of dissolved oxygen forming thermal donors at low temperatures into a beneficial process. The gettering layer is designed to capture oxygen during these same low-temperature heat treatments, transforming what would be a harmful oxygen diffusion process into a beneficial simultaneous gettering operation that maintains device characteristics while removing impurities
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 method allows for the production of semiconductor devices with stable characteristics and reduced variability in resistivity and metal contamination, eliminating the need for extensive oxygen reduction during wafer production, thus simplifying and cost-reducing the manufacturing process.
Implementation Method 1
When the silicon substrate (or wafer) is heat treated at a low temperature during the semiconductor device manufacturing process, the dissolved oxygen forms thermal donors
Implementation Method 2
a trace-bearing portion provided in said second surface and including a trace of removal of at least a portion of a gettering layer for gettering dissolved oxygen or residual metal in said silicon substrate
Data Source
AI summary
A device and a device manufacturing process. First, a gettering layer is formed on the bottom surface of a silicon substrate. Gates having a MOS structure are then formed on the principal surface of the silicon substrate, and the gettering layer is removed. According to this manufacturing method, the formation of the gates having a MOS structure is performed such that the gettering layer getters dissolved oxygen present in the silicon substrate. This reduces the concentration of dissolved oxygen in the silicon substrate, resulting in improved device characteristics.