Gate Electrode Thickness Control via Sacrificial Plug Removal
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Solution Overview
Problem
In device manufacturing, particularly for analog semiconductor integrated circuits, it is challenging to control the thickness of gate electrode films on transistors with different threshold voltages due to residue issues from mask materials in recessed areas, which hinder etching processes and film formation.
Innovation Solution
A method involving the burial of a thermally decomposable organic sacrificial material in recesses, followed by annealing to decompose the material, and the use of a preliminary sealing film to facilitate its removal, thereby preventing residue formation and enabling precise control over gate electrode film thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mask material is used to protect transistors during etching, then selective removal of gate electrode films is achieved, but residue remains in recessed areas hindering subsequent processing
Solution Approach 1:
The patent extracts the harmful mask material from the recessed areas by using a sacrificial plug structure. The sacrificial plug is selectively removed through the preliminary sealing film via thermal decomposition, taking out the residue problem before it can interfere with subsequent gate electrode film formation.
Solution Approach 2:
The preliminary sealing film acts as an intermediary layer that enables selective removal of the sacrificial plug material. This mediator allows the etching solution to reach and remove the sacrificial plug in recessed areas while protecting other regions, preventing mask material residue formation.
2Manufacturing precision
If multiple lamination and removal steps are repeated to form transistors with different gate electrode film thicknesses, then threshold voltage control is achieved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary action by forming sacrificial plugs in recessed areas before the gate electrode film lamination step. This preliminary placement of sacrificial material simplifies the subsequent process, as the plugs are automatically removed through thermal decomposition during a single annealing step, eliminating the need for multiple repeated lamination and removal cycles.
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 protects recesses during processing, reduces residue generation, and allows for the formation of transistors with gate electrode films of varying thicknesses, enhancing the control over threshold voltages and manufacturing precision.
Implementation Method 1
a first removal step of removing the sacrificial material in the recess through the preliminary sealing film, by annealing the workpiece at a first temperature and thermally decomposing the sacrificial material
Data Source
AI summary
There is provided a method of manufacturing a device, which comprises: a preparation step of preparing a workpiece having a recess formed therein; a burying step of burying a sacrificial material composed of a thermally decomposable organic material in the recess; a lamination step of laminating a preliminary sealing film on the sacrificial material buried in the recess; a first removal step of removing the sacrificial material in the recess through the preliminary sealing film, by annealing the workpiece at a first temperature and thermally decomposing the sacrificial material; a processing step of performing a predetermined process on a portion other than the recess in the workpiece, in a state in which the recess is covered with the preliminary sealing film; and a second removal step of removing the preliminary sealing film.