Integrated Circuit Metal Gate Height Control via Mask Protection
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Solution Overview
Problem
Conventional polysilicon gates in semiconductor devices face issues such as boron penetration and depletion effects, leading to inferior performance and gate capacitance reduction, while the transition to metal gates introduces challenges like gate height loss and metal residue during the replacement metal gate process.
Innovation Solution
A manufacturing method for integrated circuits that involves forming a mask structure corresponding to the semiconductor gate before the replacement metal gate process, ensuring the semiconductor gate is protected and avoiding gate height loss and metal residue by maintaining the second mask structure's coverage during the dummy gate removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask structure is formed on the semiconductor gate before exposing the dummy gate during the replacement metal gate process, then gate height loss and metal residue issues are prevented, but the manufacturing process complexity increases
Solution Approach 1:
The mask structure is formed on the semiconductor gate before the dummy gate exposure step, preparing the gate structure in advance to prevent gate height loss and metal residue during subsequent processing. This preliminary protection action ensures the semiconductor gate maintains its integrity throughout the replacement metal gate process.
Solution Approach 2:
The mask structure serves as an intermediary protective layer between the semiconductor gate and the harsh chemical etching environment during dummy gate removal. This intermediary layer prevents direct contact between the etchant and the semiconductor gate, thereby preventing gate height loss and metal residue formation.
2Reliability
If the second mask structure remains on the semiconductor gate during dummy gate removal, then the semiconductor gate is protected from damage, but additional removal steps are required
Solution Approach 1:
The second mask structure is left on the semiconductor gate after the first removal step as a pre-prepared protective layer. This preliminary protection is maintained through the dummy gate removal process, ensuring the semiconductor gate remains intact throughout the potentially damaging etching operation.
Solution Approach 2:
The mask removal process is segmented into multiple steps: first removing the initial mask structure, then performing the dummy gate removal while the second mask structure remains protective, and finally removing the second mask structure. This segmentation allows the semiconductor gate to be protected during the most critical etching step while still requiring eventual removal of the protective layer.
Data Source
AI summary
A manufacturing method of an integrated circuit includes following steps. A dummy gate with a first mask structure formed thereon and a semiconductor gate with a second mask structure formed thereon are formed on a substrate. A top surface of the semiconductor gate is lower than a top surface of the dummy gate. A first removing process is performed to remove the first mask structure and a part of the second mask structure. A dielectric layer is formed covering the dummy gate, the semiconductor gate, and the second mask structure. A second removing process is performed to remove the dielectric layer above the dummy gate. The dummy gate is removed for forming a trench. A metal gate structure is formed in the trench. The semiconductor gate is covered by the second mask structure during the second removing process and the step of removing the dummy gate.