Tone Inversion Lithography for Ultrafine Patterning

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Solution Overview

Problem

Current semiconductor manufacturing techniques face challenges in achieving precise and accurate patterning of ultrafine structures, particularly in reducing critical dimension (CD) and ensuring CD uniformity for advanced process nodes, which is crucial for increased feature density in semiconductor devices.

Innovation Solution

A lithography method employing tone inversion techniques, involving a patterning structure with specific layers such as an etch stop layer, amorphous carbon, adhesion, amorphous silicon, and hard mask layers, to form a first pattern of protruding structures that define recessed features, allowing for precise etching and reduction of masking layers, enabling the creation of detailed nanometer-scale features like source/drain junctions with precise CD control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If traditional multi-layer masking is used for ultrafine patterning, then feature density can be increased, but the number of masking layers increases and manufacturing complexity increases

Engineering Contradiction:

Improvefeature densityVSAvoidnumber of masking layers

Core Design Contradiction:

Area of moving objectVSDevice complexity

Solution Approach 1:

The patent applies tone inversion by forming a first pattern of protruding structures that define recessed features, then using these recessed features to create a second pattern of protruding structures. This inversion approach reduces the number of masking layers needed while achieving the same feature density, directly resolving the contradiction between increased feature density and reduced manufacturing complexity

Inventive Principle:

Principle #13The other way round (Inversion)

2Area of moving object

If critical dimension is reduced to increase feature density, then more features can be packed, but patterning resolution and precision requirements increase

Engineering Contradiction:

Improvefeature densityVSAvoidpatterning resolution

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

By inverting the tone of the pattern, the patent enables the use of bright field masks which provide an improved lithographic process window. This inversion technique allows for precise patterning at reduced critical dimensions, achieving high feature density while maintaining the required patterning resolution and precision

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces an image reverse material layer as an intermediary between the lithographic exposure and the final pattern transfer. This intermediate layer enables tone inversion and facilitates precise pattern definition at ultrafine dimensions, acting as a mediator that improves patterning resolution while supporting reduced critical dimensions

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10453751B2Tone inversion method and structure for selective contact via patterning

Publication Date: 2019.10.22 GLOBALFOUNDRIES US INC

AI summary

A tone inversion method for integrated circuit (IC) fabrication includes providing a substrate with a layer of amorphous carbon over the substrate and a patterning layer over the amorphous carbon layer. The patterning layer is etched to define a first pattern of raised structures and a complementary recessed pattern that is filled with a layer of image reverse material. The first pattern of raised structures is then removed to define a second pattern of structures comprising the image reverse material. A selective etching step is used to transfer the second pattern into a dielectric layer disposed between the layer of amorphous carbon and the substrate.