Angled Gate Cut Structures Under Tight Lithography Alignment
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Solution Overview
Problem
As integrated circuits scale down, forming high-density semiconductor devices with tight alignment tolerances becomes challenging due to lithography constraints, leading to potential failure points and limited width of gate cut structures, which restricts the landing area for conductive contacts.
Innovation Solution
The formation of integrated circuits with angled gate cut structures, where the top portion of the gate cut structures is laterally etched to increase the width, allowing for a larger landing area for conductive contacts by reducing the critical dimension of the gate cut structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate cut structures are made narrower to prevent shorting and meet lithography constraints, then shorting risk is reduced and lithography compliance is improved, but the landing area for contacts is reduced
Solution Approach 1:
The gate cut structure is designed with an asymmetric cross-section featuring a wider bottom portion and a narrower top portion. This asymmetric geometry allows the structure to maintain electrical isolation function at the critical narrow top region while providing a wider landing area at the bottom for reliable contact formation, thus resolving the contradiction between preventing shorting and providing sufficient contact area
Solution Approach 2:
The solution transitions from a uniform width gate cut structure to one with varying width through the vertical dimension. By creating an angled or tapered profile where the width changes from bottom to top, the invention utilizes the vertical dimension to simultaneously satisfy both the narrow width requirement at the top for shorting prevention and the wide area requirement at the bottom for contact landing
2Ease of manufacture
If traditional vertical gate cut structures are used, then fabrication is simpler, but the landing area for contacts is insufficient for high-density circuits
Solution Approach 1:
The angled or tapered profile of the gate cut structure is formed during the initial etching process before contact formation. This preliminary shaping of the gate cut structure ensures that the wider landing area is already in place when subsequent contact formation steps occur, eliminating the need for additional complex fabrication steps while providing sufficient contact area
Solution Approach 2:
The invention changes the geometric parameters of the gate cut structure by introducing an angle or taper rather than using a vertical profile. This parameter change from vertical to angled creates a trapezoidal cross-section that provides increased landing area at the bottom while maintaining the necessary narrow dimension at the top, improving contact area without significantly complicating the fabrication process
Data Source
AI summary
Techniques are provided herein to form an integrated circuit having gate cut structures or plug structures between source or drain regions, with an angled cut made to the top portion of the structures. In an example, a semiconductor device includes a semiconductor region extending between source and drain regions, and a gate structure extending over the semiconductor region. A gate cut structure is present adjacent to the semiconductor device and interrupts the gate structure. The gate cut structure has a first width along a first plane that extends through the semiconductor region and a second width along a second plane parallel to the first plane and above the semiconductor region, where the first width is greater than the second width. Similar angled plug structures may be provided adjacent to the source and drain regions to increase the landing area made to the metal contacts on the source and drain regions.