Self-Aligned Contact Formation via Dummy Gate Replacement
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Solution Overview
Problem
As semiconductor device pitches are scaled down, the process windows for forming contacts become progressively smaller, necessitating a new method to extend these windows and simplify the fabrication process while reducing substrate damage.
Innovation Solution
The method involves forming gate stacks with dummy gates and sidewall spacers on a semiconductor substrate, removing the dummy gates and a material layer to create recesses, and filling these recesses with a conductive material to form self-aligned contacts, which are favorable for extending process windows and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional contact formation methods are used with scaled down pitches, then device density increases, but process windows become progressively smaller
Solution Approach 1:
The method performs preliminary actions by forming dummy gates and material layers before contact formation, and removing them together in a single etching step. This preliminary structuring enables self-aligned contact formation, which extends process windows while maintaining scaled-down pitches and high device density.
Solution Approach 2:
The dummy gates and material layers serve as intermediary structures that facilitate the contact formation process. These temporary structures enable precise alignment and controlled etching, extending process windows while allowing continued scaling of device pitches for higher density.
2Manufacturing precision
If multiple separate steps are used for contact formation, then contact precision can be maintained, but process complexity increases
Solution Approach 1:
The method merges the removal of dummy gates and material layers into a single etching step, and combines contact alignment with gate structure formation. This consolidation maintains contact precision through self-alignment while significantly reducing process complexity and the number of separate fabrication steps.
Solution Approach 2:
The dummy gates and material layers serve multiple functions: they define contact locations, provide etch masks, and enable self-alignment. This multi-functionality maintains contact precision while simplifying the overall process by eliminating the need for separate alignment and masking steps.
3Manufacturing precision
If aggressive etching is used to form contacts in scaled down devices, then contact dimensions can be controlled, but substrate damage increases
Solution Approach 1:
The method provides beforehand cushioning by forming the dummy gates and material layers that act as protective masks during etching. These structures cushion the substrate from direct aggressive etching, enabling precise contact dimension control while minimizing substrate damage through the protective barrier.
Solution Approach 2:
The dummy gates and material layers serve as intermediary protective structures during the etching process. They mediate between the etching chemistry and the substrate, allowing controlled removal of material to define contacts while protecting the substrate from damage through the sacrificial mask layers.
Data Source
AI summary
It is provided a method for forming a semiconductor device comprising: forming a material layer which exposes dummy gates and sidewall spacers and fills spaces between two adjacent gate stacks, and the material of the material layer is the same as the material of the dummy gate; removing the dummy gates and the material layer to form recesses; filling the recesses with a conductive material, and planarizing the conductive material to expose the sidewall spacers; breaking the conductive material outside the sidewall spacers to form at least two conductors, each of the conductors being only in contact with the active region at one side outside one of the sidewall spacers, so as to form gate stack structures and first contacts. Besides, a semiconductor device is provided. The method and the semiconductor device are favorable for extending process windows in forming contacts.