In-Situ HCl Etch for Defect Removal in HOT CMOS Transistors
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing defects at the interface of direct silicon bond wafer layers during the production of hybrid orientation technology (HOT) semiconductor devices, particularly due to crystal defects formed during silicon phase epitaxy, which can lead to thermal stresses and wafer warping when high-temperature anneal processes are used.
Innovation Solution
A method involving the use of hydrochloric acid etching within an epitaxial reactor chamber to remove crystallographic defects at the interface between amorphized and unamorphized cleaved wafer layers, combined with rapid thermal processing and silicon implantation to recrystallize the amorphous silicon layer, thereby avoiding high-temperature anneal processes and minimizing thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature anneal processes are used to remove crystal defects at the interface, then defect removal is achieved, but thermal stresses and wafer warping occur
Solution Approach 1:
The patent changes the temperature parameter from high-temperature anneal to low-temperature HCl etch process. Instead of using thermal energy to remove defects, the invention uses chemical etching at lower temperatures to selectively remove defective material at the interface, thereby eliminating thermal stress and wafer warping while still achieving defect removal
Solution Approach 2:
The patent replaces the thermal-mechanical annealing process with a chemical etching process. The HCl etch chemically reacts with and removes the recrystallization border defects through oxidation, substituting the mechanical/thermal approach with a chemical solution that achieves the same defect removal goal without generating thermal stress
2Reliability
If high-temperature anneal processes are used to remove crystal defects, then defect removal is achieved, but wafer warping occurs
Solution Approach 1:
The patent changes the temperature parameter from high-temperature anneal to low-temperature HCl etch process. Instead of using thermal energy to remove defects, the invention uses chemical etching at lower temperatures to selectively remove defective material at the interface, thereby eliminating wafer warping while still achieving defect removal
Solution Approach 2:
The patent replaces the thermal-mechanical annealing process with a chemical etching process. The HCl etch chemically reacts with and removes the recrystallization border defects through oxidation, substituting the mechanical/thermal approach with a chemical solution that achieves the same defect removal goal without causing wafer deformation
3Loss of substance
If conventional etching processes are used, then material removal is achieved, but interface defects remain
Solution Approach 1:
The patent introduces HCl as a chemical intermediary that facilitates selective removal of interface defects. The HCl etch acts as a mediator between the amorphized and unamorphized regions, chemically reacting with the recrystallization border defects to enable their removal while preserving the surrounding healthy material, thereby achieving both material removal and defect elimination
Solution Approach 2:
The patent applies local quality by making the etching process selective to specific regions. The HCl etch selectively attacks the recrystallization border defects at the interface between amorphized and unamorphized regions while leaving the surrounding material intact. This localized chemical reaction enables precise defect removal without compromising the overall wafer structure
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 effectively reduces or eliminates interface defects without requiring high-temperature anneal, preserving the thermal budget and enhancing the quality of semiconductor wafers for advanced CMOS device nodes, allowing for improved transistor performance by maintaining wafer integrity and enabling faster NMOS and PMOS device operation.
Implementation Method 1
exposing an interface between an amorphized, recrystallized cleaved wafer layer having a first crystal orientation and an unamorphized cleaved wafer layer having a second crystal orientation different from the first crystal orientation to an etch using hydrochloric acid (HCl) to remove a crystallographic defect
Implementation Method 2
dosing a semiconductor wafer substrate assembly comprising an exposed cleaved wafer portion and an unexposed cleaved wafer portion which overlies a semiconductor wafer with a silicon implant. The dosing is performed to amorphize the exposed cleaved wafer portion
Implementation Method 3
Within an epitaxial reactor chamber, rapid thermal processing of the amorphous silicon layer can be performed to recrystallize the amorphous silicon layer and to provide a crystalline silicon layer
Implementation Method 4
Within the epitaxial reactor chamber, the interface is exposed to a hydrochloric acid etch
Data Source
AI summary
A method for reducing defects at an interface between a amorphized, recrystallized cleaved wafer layer and an unamorphized cleaved wafer layer can comprise an anneal and an exposure to hydrochloric acid. The anneal and acid exposure can be performed within an epitaxial reactor chamber to minimize wafer transport.