Semiconductor Contact Plug Formation Using Multilayer Mask Segmentation
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Solution Overview
Problem
Current semiconductor device formation techniques face challenges in miniaturization, particularly with position shifts of contact plugs affecting electrical performance due to inadequate photoresist and lithography techniques, leading to issues with metal gate and contact plug formation.
Innovation Solution
A method involving a multilayer mask layer with specific slot-cut and contact slot patterns is used to form contact slots, allowing for precise etching and separation of contact slot extensions, improving the electrical connection between source/drain and metal gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current photoresist and lithography techniques are used to form contact plugs, then the manufacturing process is simple, but the position accuracy of contact plugs deteriorates causing shifts that may penetrate the metal gate
Solution Approach 1:
The mask layer is divided into multiple layers (first mask layer and second mask layer) with different functions. The first mask layer defines the contact plug position, while the second mask layer defines the metal gate position. This segmentation allows independent optimization of each mask layer's pattern accuracy, resolving the contradiction between position accuracy and process simplicity.
Solution Approach 2:
A mandrel structure is introduced as an intermediary element between the first and second mask layers. The mandrel serves as a reference structure that enables precise alignment of the second mask layer relative to the first mask layer, thereby achieving high position accuracy for both contact plugs and metal gates without requiring complex single-step lithography.
2Manufacturing precision
If the contact slot is formed as a single extending stripe, then the etching process is simple, but the electrical connection accuracy to source/drain regions deteriorates
Solution Approach 1:
The contact slot pattern is segmented into multiple parts using the multilayer mask structure. The first mask layer creates a slot-cut pattern that divides the extending stripe into separate segments, while the second mask layer adds contact slot patterns at specific positions. This segmentation improves electrical connection accuracy by ensuring precise contact with source/drain regions while maintaining etching efficiency through the structured approach.
Data Source
AI summary
A method of forming a semiconductor device includes following steps. Firstly, a substrate having a transistor is provided, where the transistor includes a source/drain region. A dielectric layer is formed on the substrate, and a contact plug is formed in the dielectric layer to electrically connect the source/drain region. Next, a mask layer is formed on the dielectric layer, where the mask layer includes a first layer and a second layer stacked thereon. After this a slot-cut pattern is formed on the second layer of the mask layer, and a contact slot pattern is formed on the first layer of the mask layer. Finally, the second layer is removed and a contact opening is formed by using the contact slot pattern on the first layer.