Replacement Gate Opening Profile for Stable Metal Gate Etch Back
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Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing due to damages such as semiconductor fin punch through and short circuits during metal gate etch back processes, which affect etching rate uniformity and stability in the production of advanced IC devices.
Innovation Solution
The method involves adjusting the profile of sacrificial gate structures to be more straight, rather than bowl-shaped, and performing a pullback etching process of sidewall spacers before depositing the work function metal layer to achieve a wider opening for metal gate filling, thereby improving etching rate uniformity and stability during the replacement gate process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal gate etching back process is performed with conventional bowl-shaped sacrificial gate structures, then gate electrode formation is achieved, but fin punch through damages occur and etching rate uniformity deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the sacrificial gate structure from a conventional bowl-shaped profile to a straight profile with adjusted dimensions. Specifically, the straight profile reduces over-etching into the fin region while maintaining adequate gate coverage, thereby preventing fin punch through damage and improving etching rate uniformity across the substrate.
Solution Approach 2:
The patent performs a pullback etching process on the sidewall spacers before depositing the work function metal layer. This preliminary action creates a wider opening for metal gate filling, which allows for more uniform etching rates during subsequent processes and prevents damage to the fin structure by establishing proper spacing and access channels in advance.
2Reliability
If conventional metal gate etching back is performed, then gate electrodes are formed, but short circuits between gate electrodes and source/drain contacts occur
Solution Approach 1:
The patent modifies the sacrificial gate structure profile from bowl-shaped to straight, and adjusts the sidewall spacer dimensions through pullback etching. These parameter changes ensure proper spatial separation between gate electrodes and source/drain contacts, preventing short circuits while maintaining electrical isolation reliability.
Solution Approach 2:
The pullback etching of sidewall spacers is performed as a preliminary action before metal gate deposition. This creates predetermined spacing and wider openings that facilitate proper gate electrode formation and ensure adequate isolation from source/drain regions, preventing future short circuits.
3Manufacturing precision
If bowl-shaped sacrificial gate structures are used, then gate formation is completed, but etching rate stability deteriorates during replacement gate process
Solution Approach 1:
The patent changes the sacrificial gate profile parameter from bowl-shaped to straight, which fundamentally alters the etching behavior during the replacement gate process. The straight profile provides more uniform etching rates and better process stability, eliminating the variability associated with the curved bowl shape.
Solution Approach 2:
The pullback etching of sidewall spacers is performed in advance to create optimal geometric conditions for the replacement gate process. This preliminary shaping action ensures that subsequent etching operations proceed with stable and uniform rates, improving overall manufacturing precision.
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 fin damages and short circuits between gate electrodes and source/drain contacts, enhancing the uniformity and stability of the etch back process, leading to improved manufacturing outcomes for advanced IC devices.
Implementation Method 1
performing a pullback etching process of sidewall spacers
Implementation Method 2
depositing a gate dielectric layer on the CESL exposed to the gate cavity; forming a work function metal layer over the gate dielectric layer
Data Source
AI summary
Some embodiments provide a process of tunning sidewall profiles of gate openings prior to filling a replacement gate electrode layer therein to improve etching rate uniformity and stability during a subsequent gate electrode etch back process. Particularly, the profile sacrificial gate electrode is adjusted to be more straight profile rather than a bowl type profile, which reduces the seam void created in the replacement gate electrode during the replacement gate process. In some embodiments, tuning the profile of gate opening further includes performing a pullback etching process of the sidewall spacers prior to depositing gate dielectric layer and work function metal layer to achieve a wider opening for metal gate filling in the replacement gate process.