SOI Wafer Fabrication With Impurity Gettering for Metal-Free Top Silicon
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon on insulator (SOI) technology faces challenges with metal contamination during the fabrication process, leading to surface defects and residual metal impurities in the top silicon layer, which affect the quality of semiconductor devices.
Innovation Solution
An impurity competing layer is introduced as a metal gettering layer on the dummy wafer to absorb and remove metal contaminants during the bonding and annealing process, reducing residual metal contamination in the SOI structure. This layer can be formed through various methods, including implantation or deposition, and is later removed after thinning, functioning as an etch-stop layer if needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding process is used to fabricate SOI structure, then manufacturing simplicity is maintained, but metal contamination and surface defects increase
Solution Approach 1:
A dummy wafer is introduced as an intermediary component in the bonding process. The dummy wafer includes a dummy substrate and a device layer, which serves as a mediator to prevent metal contamination from transferring to the carrier wafer during bonding and annealing processes. This intermediary structure absorbs or traps metal impurities, thereby protecting the final SOI structure from contamination while maintaining process feasibility
Solution Approach 2:
The dummy wafer is prepared in advance with specific structural characteristics before the bonding process. The device layer on the dummy wafer is pre-configured to function as a metal gettering layer that will actively capture metal contaminants during subsequent bonding and annealing steps. This preliminary preparation ensures that the contamination prevention mechanism is already in place before the actual bonding occurs
2Manufacturing precision
If bonding and annealing processes are performed, then SOI structure is formed, but residual metal impurities remain in the top silicon layer
Solution Approach 1:
The bonding and annealing processes, which normally cause metal contamination by mobilizing metal impurities, are converted into beneficial processes. The dummy wafer's device layer acts as a trap that captures these mobilized metal impurities during bonding and annealing. The harmful metal migration is redirected toward the dummy wafer instead of the carrier wafer, transforming a potentially damaging process into a contamination-prevention mechanism
Solution Approach 2:
Metal impurities are extracted from the carrier wafer and top silicon layer by transferring them to the dummy wafer during bonding and annealing processes. The dummy wafer serves as a removable container for these extracted impurities. After the bonding is complete, the dummy wafer can be removed, taking the captured metal contaminants with it, thereby leaving the carrier wafer and top silicon layer purified
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 implementation of the impurity competing layer effectively reduces metal contamination in the SOI structure, enhancing the quality and reliability of semiconductor devices by minimizing surface defects and residual metal impurities.
Implementation Method 1
An impurity competing layer is introduced as a metal gettering layer on the dummy wafer to absorb and remove metal contaminants during the bonding and annealing process
Implementation Method 2
performing an annealing process wherein the impurity competing layer absorbs metal from an upper portion of the dummy substrate
Data Source
AI summary
Various embodiments of the present application are directed to a method for forming a semiconductor-on-insulator (SOI) device with an impurity competing layer to absorb potential contamination metal particles during an annealing process, and the SOI structure thereof. In some embodiments, an impurity competing layer is formed on the dummy substrate. An insulation layer is formed over a support substrate. A front side of the dummy wafer is bonded to the insulation layer. An annealing process is performed and the impurity competing layer absorbs metal from an upper portion of the dummy substrate. Then, a majority portion of the dummy substrate is removed including the impurity competing layer, leaving a device layer of the dummy substrate on the insulation layer.