Sidewall Image Transfer for High-Density Pattern Definition
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Solution Overview
Problem
The existing methods for producing patterns with small dimensions in integrated circuits face challenges due to increased technological constraints in photolithography equipment, particularly in aligning photolithographic levels and defining lateral dimensions, which lead to degradation of physical-chemical properties and reduced thickness of materials.
Innovation Solution
A method involving a substrate with a layer of first material covered by multiple etching masks, where a secondary area of the covering layer is partially etched to form a salient pattern, followed by deposition and etching of masking material to create lateral spacers, allowing for the formation of a third etching mask that defines the pattern of the first material, thereby simplifying the pattern definition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography and etching equipment are continuously improved to form increasingly dense patterns, then manufacturing precision is improved, but device complexity and technological constraints increase beyond compatibility with current equipment
Solution Approach 1:
The pattern formation process is segmented into multiple steps: initial photolithography defines positions, then lateral spacers are formed through deposition and anisotropic etching to define lateral dimensions. This segmentation allows each step to be optimized independently, achieving high pattern density without overwhelming equipment constraints.
Solution Approach 2:
The invention transitions from defining all pattern dimensions in the planar photolithography step to utilizing the vertical dimension through conformal deposition of lateral spacers. The spacer thickness, controlled by deposition parameters, defines the lateral pattern dimensions, adding a vertical control dimension to the otherwise planar process.
2Manufacturing precision
If lateral dimensions are defined by photolithography, then manufacturing precision is improved, but alignment constraints between different photolithographic levels increase
Solution Approach 1:
Lateral dimension definition is moved from the photolithography plane to the vertical deposition dimension. Conformal lateral spacers are deposited over the photolithographically defined structures, and their thickness (controlled by deposition) defines the final lateral dimensions, eliminating the need for complex alignment between multiple photolithographic levels.
Solution Approach 2:
The lateral spacers act as an intermediary between the photolithographically defined structures and the final pattern. The spacers are formed through deposition and anisotropic etching, serving as a bridge that transfers the positional information from photolithography while defining the lateral dimensions through a different mechanism that does not require photolithographic alignment.
3Manufacturing precision
If etching chemistry is made highly selective with respect to first material, then manufacturing precision is improved, but etching selectivity is lost and physical-chemical properties of first material are degraded
Solution Approach 1:
The lateral spacers serve as a protective intermediary layer during the etching of the first material. By forming the spacers first through deposition and anisotropic etching, they provide a protective barrier that allows subsequent etching of the first material to proceed without direct exposure to aggressive etching chemistry, thereby maintaining the physical-chemical properties of the first material while still achieving precise pattern reproduction.
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 method provides greater flexibility and efficiency in defining patterns, reducing technological constraints and improving the alignment of photolithographic levels, while maintaining the physical-chemical properties of the materials, enabling the production of patterns with larger dimensions and improved resolution.
Implementation Method 1
covering layer 3 is etched, for example by plasma, through etching mask 4 to reproduce the latter in the pattern of etching mask 4
Implementation Method 2
The etching chemistry is chosen selective with respect to the etching mask and with respect to first material 2 in order to eliminate a part of covering layer 3 without damaging first material 2
Implementation Method 3
The etching chemistry is chosen as anisotropic as possible in order to reproduce the pattern of etching mask 4 faithfully in covering layer 3
Implementation Method 4
masking material 5 is deposited and then etched so as to form one or more lateral spacers. Masking material 5 is deposited in conformal manner and is anisotropically etched so as to localize it on the side walls
Implementation Method 5
a masking material 5 is deposited
Data Source
AI summary
The substrate is provided with a layer of first material, a first etching mask, a covering layer and a second etching mask. The covering layer has a covered main area and an uncovered secondary area. The secondary area of the covering layer is partially etched via the second etching mask to form a salient pattern. Lateral spacers are formed around the salient pattern defining a third etching mask. The second etching mask is eliminated. The covering layer is etched by means of the third etching mask to form a salient pattern in the covering layer and to uncover the first etching mask and the first material. The layer of first material is etched to form the pattern made from the first material.