Oxidizing and Etching Material Lines for Critical Dimension Control
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Solution Overview
Problem
Conventional lithography techniques are inadequate for patterning fine pitches in semiconductor fabrication, particularly at the 14 nanometer node and beyond, as they fail to effectively manage critical dimensions of material lines in FinFET and BEOL metal connections.
Innovation Solution
A method involving the use of a hard mask and patternable layers, where material lines are oxidized and then etched to achieve different critical dimensions, allowing for selective fine-tuning of spacer critical dimensions using a combination of oxidation and wet/dry oxide etching, thereby enabling precise control over multi-fin widths, multi-gate lengths, and BEOL metal connections without requiring additional masking steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography is used for patterning, then the process is simple and straightforward, but it is no longer capable of patterning fine pitches at 14 nanometers node and beyond
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple stages: forming initial material lines, depositing spacers, selectively oxidizing certain lines, and performing etching steps. This multi-stage approach enables fine pitch patterning at 14nm node by breaking down the complex patterning task into manageable segments, each achieving a specific function in the overall fabrication sequence.
Solution Approach 2:
The patent employs preliminary action through pre-oxidation of select material lines before the final patterning step. By oxidizing certain lines in advance and using them as sacrificial elements, the process prepares the structure for subsequent spacer formation and pattern transfer, enabling precise control over critical dimensions at advanced nodes.
2Manufacturing precision
If spacer defined lithography (SIT) is used, then fine line widths can be achieved, but only one critical dimension is offered
Solution Approach 1:
The patent applies local quality by implementing selective oxidation where only specific material lines are oxidized while others remain unoxidized. This creates different critical dimensions in different regions of the same structure - oxidized lines maintain one CD while unoxidized lines with spacers achieve another CD, enabling multi-CD patterning from a single lithographic layer.
Solution Approach 2:
The patent utilizes parameter changes by varying the oxidation state of material lines to achieve different critical dimensions. By controlling which lines undergo oxidation and to what extent, the process generates multiple CD values (e.g., 10nm, 15nm, 20nm) from the same starting material layer, providing versatility in device design.
3Productivity
If additional masking steps are avoided, then productivity is improved, but control over multiple critical dimensions becomes difficult
Solution Approach 1:
The patent applies self-service through self-aligned spacer formation where spacers automatically position themselves relative to the material lines. The spacer width is determined by the deposition thickness rather than requiring separate lithographic definition, and the selective oxidation pattern is maintained through the process without additional masking, achieving multi-CD control with enhanced productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise control over critical dimensions, enabling effective patterning of semiconductor structures with multiple fins and gates of varying widths or lengths, and BEOL metal connections, enhancing the capability for fine pitch patterning beyond the limitations of conventional techniques.
Implementation Method 1
oxidizing the at least one unprotected material line to increase the critical dimension
Implementation Method 2
etching at least a portion of the oxidized unprotected material line so that the etched critical dimension is different
Data Source
AI summary
A method includes, for example, providing a starting semiconductor structure having a plurality of material lines disposed over a hard mask, and the hard mask disposed over a patternable layer, forming a protective layer over a portion of at least one material line, the at least one protected material line and at least one unprotected material line having a same critical dimension, oxidizing the at least one unprotected material line to increase the critical dimension compared to the first critical dimension of the at least one protected material line, and etching at least a portion of the oxidized unprotected material line so that the etched critical dimension of the at least one etched material line is different from the first critical dimension of the at least one protected material line.