Semiconductor Source/Drain Contact Recessing for Alignment Shift
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Solution Overview
Problem
In traditional semiconductor structures, the increasing density and shrinking size of devices lead to alignment shifts during the formation of gate contacts, causing short circuits between self-aligned contact structures and gates, which narrows the process window and reduces manufacturing yield.
Innovation Solution
A recessing process is employed to lower the top surface of the source/drain contact below the gate structure, followed by the formation of a stop layer, which enhances the process window by preventing short circuits and improving alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the spacing between gates is reduced to increase device density, then the device density is improved, but the alignment precision deteriorates causing short circuits between self-aligned contact structure and gates
Solution Approach 1:
A recessing process is performed on the self-aligned contact structure before forming the gate contact, creating a stepped configuration. This preliminary action lowers the contact structure's top surface relative to the gate top surface, establishing a height difference that prevents short circuits even when alignment shifts occur during subsequent gate contact formation.
2Ease of manufacture
If the self-aligned contact structure is formed at the same level as the gate, then the manufacturing process is simplified, but the process window narrows due to alignment sensitivity
Solution Approach 1:
The recessing process is performed as a preliminary step before gate contact formation, creating a stepped configuration where the self-aligned contact structure is lower than the gate. This preliminary height adjustment expands the process window by providing a buffer against alignment shifts, allowing greater manufacturing flexibility without compromising reliability.
Data Source
AI summary
A manufacturing method of a semiconductor structure includes the following steps. Gate structures are formed on a semiconductor substrate. A source/drain contact is formed between two adjacent gate structures. The source/drain contact is recessed by a recessing process. A top surface of the source/drain contact is lower than a top surface of the gate structure after the recessing process. A stop layer is formed on the gate structures and the source/drain contact after the recessing process. A top surface of the stop layer on the source/drain contact is lower than the top surface of the gate structure. A semiconductor structure includes the semiconductor substrate, the gate structures, a gate contact structure, and the source/drain contact. The source/drain contact is disposed between two adjacent gate structures, and the top surface of the source/drain contact is lower than the top surface of the gate structure.