Semiconductor Device Trench Contact Plug Formation
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Solution Overview
Problem
In semiconductor devices with buried gate transistors, the varying trench widths lead to non-uniform filling of gate electrode material, causing thickness issues and increasing the risk of short circuits during contact plug formation, which reduces fabrication yield and requires strict etching control to prevent contact failures.
Innovation Solution
The semiconductor device incorporates a groove structure with a wider pad trench and a narrower gate trench, where a pad contact plug is formed in the wider trench, and a gate contact plug is formed over the pad contact plug, with an insulating side wall covering the pad and gate contact plugs, and a cap insulating film on the buried gate electrode, allowing for improved contact plug formation and reduced short circuit risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform trench width is used for both pad and gate regions, then the fabrication process is simpler, but the contact plug formation becomes difficult to control and short circuits occur more frequently
Solution Approach 1:
The patent applies local quality by creating different trench widths in different regions: a first trench width for the pad contact plug region and a second trench width (narrower than the first) for the gate contact plug region. This allows optimized contact plug formation in each region - wider trenches for pad contacts that require robust formation, and narrower trenches for gate contacts that require precise alignment and controlled etching to prevent short circuits.
2Reliability
If strict etching control is implemented to prevent contact failures, then the contact plug formation reliability improves, but the fabrication process complexity and time increase
Solution Approach 1:
The patent implements preliminary action by pre-forming grooves with different widths in the semiconductor substrate before contact plug formation. The wider first groove portion and narrower second groove portion are created in advance, which guides the subsequent contact plug formation process. This preliminary structural differentiation reduces the need for strict real-time etching control during contact plug fabrication, as the groove geometry itself provides process guidance and tolerance.
Data Source
AI summary
A semiconductor device includes the following elements. A semiconductor substrate includes an isolation region. The semiconductor substrate has a groove in the isolation region. A pad electrode is disposed in the groove. A pad contact plug is disposed in the groove. The pad contact plug is disposed on the pad electrode. A gate contact plug is disposed on the pad contact plug. The gate contact plug is electrically coupled through the pad contact plug to the pad electrode. An insulating side wall is disposed in the groove. The insulating side wall covers side surfaces of the pad contact plug and a lower portion of the gate contact plug, and the insulating side wall covers a part of an upper surface of the pad electrode.