Multi-material selective etching reverse tone patterning
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Solution Overview
Problem
Current photolithographic techniques face limitations in reducing feature size due to minimum pitch constraints, leading to complex and costly mask edge placement control, especially at nanometer scales, resulting in low production yields and high equipment costs.
Innovation Solution
A method involving the formation of multiple lines with different materials on a substrate, allowing for selective etching and increased critical dimensions and edge placement errors, which simplifies the patterning process and reduces costs by using a three-line structure instead of a conventional single line, enabling more precise control and easier mask edge placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If photolithography techniques are used to pattern ICs, then manufacturing capability is achieved, but minimum pitch constraints limit feature size reduction
Solution Approach 1:
The patent segments the patterning process into multiple steps (SADP, SAQP, LELE) to achieve sub-lithographic pitch features. Instead of attempting to pattern all features in a single lithography step, the process divides the pitch into multiple segments formed through sequential self-aligned deposition and etching operations, enabling feature sizes below the conventional photolithography minimum pitch
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional vertical structures through self-aligned deposition of mandrels and spacers. By utilizing the vertical dimension for spacer deposition on top of lithographically formed mandrels, the process achieves pitch control that is not limited by the lateral resolution of the photolithography system
2Manufacturing precision
If multi-cut or block masks are placed over lines and spaces for device patterning, then pattern transfer is achieved, but mask edge placement control becomes more complicated and difficult
Solution Approach 1:
The patent employs self-aligned processes where previously formed structures automatically serve as alignment references for subsequent steps. The spacers are deposited conformally on the mandrels, and the mandrels themselves define the precise location where spacers will form, eliminating the need for separate alignment operations and reducing mask complexity
Solution Approach 2:
The patent changes the critical dimension control parameter from mask edge placement to spacer thickness, which is controlled by conformal deposition processes. This parameter transformation shifts the precision requirement from lateral mask alignment (which is complex at small dimensions) to vertical film thickness control (which can be achieved with atomic-layer precision through ALD or CVD)
3Manufacturing precision
If tight geometric requirements are imposed on masks for 7 nm node structures, then patterning precision is improved, but production yields decrease and equipment costs increase
Solution Approach 1:
The patent uses sacrificial mandrel structures that are temporarily formed to define the final pattern but are subsequently removed. These mandrels serve their purpose during the spacer formation process and are then eliminated, allowing the use of simpler, less expensive mask structures without compromising the precision of the final pattern
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 enhances the precision and cost-effectiveness of device patterning by increasing critical dimensions and edge placement errors, allowing for more reliable and efficient pattern transfer to the substrate, thereby improving production yields and reducing equipment expenses.
Implementation Method 1
depositing a first line on the substrate in each of a plurality of gaps
Implementation Method 2
depositing a first line on the substrate in each of a plurality of gaps
Implementation Method 3
selectively etching one of the first, second or third materials relative to the other of the materials comprising the lines
Data Source
AI summary
Embodiments described herein generally relate to methods for device patterning. In various embodiments, a plurality of protrusions and gaps are formed on a substrate, and each gap is formed between adjacent protrusions. Each protrusion includes a first line, a second line and a third line. The first and third lines include a first material, and the second lines include a second material that is different from the first material. A fourth line is deposited in each gap and the fourth line includes a third material that is different than the first and second materials. Because the first, second and third materials are different, one or more lines can be removed by selective etching while adjacent lines that are made of a different material may not be covered by a mask. The critical dimensions (CD) and the edge displacement errors (EPE) of the mask are increased.