FinFET Fabrication Using Mandrel and Spacer Patterning
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Solution Overview
Problem
The miniaturization of semiconductor devices, particularly fin field effect transistors (Fin FETs), faces challenges in precisely defining fin structures and controlling etching processes due to limitations in current mask and lithography techniques, leading to issues like fin collapse and over-etching, which affect efficiency.
Innovation Solution
A method involving the formation of mandrels and spacers on a substrate, where spacers are used to create specific gap and trench patterns, allowing for precise etching and transfer of patterns to form fin-shaped structures with varying designs, such as alternating trenches and bumps, to improve fin structure precision and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current mask and lithography techniques are used to form fin structures, then the fabrication process is simpler, but the precision of fin position definition and etching control deteriorates, leading to fin collapse and over-etching
Solution Approach 1:
The fabrication process is segmented into multiple stages: first forming mandrels with initial patterns, then using these mandrels as templates to guide spacer formation, and finally using the spacers as masks for precise etching. This segmentation allows each stage to focus on a specific aspect of precision control without overwhelming the process complexity.
Solution Approach 2:
Mandrels are formed in advance with patterns that are larger than the final fin structures. These pre-formed mandrels serve as templates that guide the subsequent spacer formation and etching processes, ensuring that the final fin positions are precisely defined before the actual etching begins.
2Length of moving object
If fin width and pitch are shrunk to meet miniaturization requirements, then device miniaturization is achieved, but the control over etching time and fin structure definition deteriorates
Solution Approach 1:
Spacers are introduced as intermediary structures between the mandrels and the final fin structures. The spacers are formed with controlled thickness through atomic layer deposition (ALD), providing a precise intermediate dimension that translates the larger mandrel patterns into the smaller required fin dimensions with high precision.
Solution Approach 2:
The method changes the critical dimension control parameter from direct lithography patterning to spacer thickness control. By using ALD to deposit spacers with precisely controlled thickness, the fin width and pitch can be accurately controlled even at miniaturized dimensions, overcoming the limitations of direct lithography at small scales.
3Productivity
If traditional etching methods are used, then the process is faster and simpler, but the fin structure definition becomes imprecise, causing fin collapse
Solution Approach 1:
The mandrels are formed in advance with optimized patterns that are specifically designed to guide the etching process. These pre-formed mandrels with appropriate dimensions and spacing ensure that when etching occurs, the fin structures are properly supported and defined, preventing collapse while maintaining efficient processing.
Solution Approach 2:
The spacers serve as intermediary mask structures that provide precise geometric definition during etching. They act as a protective template that ensures uniform fin formation and prevents over-etching, thereby maintaining fin structure stability and reliability while allowing the etching process to proceed efficiently.
Data Source
AI summary
A method for fabricating semiconductor device is disclosed. First, a substrate is provided, and a first mandrel, a second mandrel, a third mandrel, and a fourth mandrel are formed on the substrate. Preferably, the first mandrel and the second mandrel include a first gap therebetween, the second mandrel and the third mandrel include a second gap therebetween, and the third mandrel and the fourth mandrel include a third gap therebetween, in which the first gap is equivalent to the third gap but different from the second gap. Next, spacers are formed adjacent to the first mandrel, the second mandrel, the third mandrel, and the fourth mandrel, and the spacers in the first gap and the third gap are removed.