Sidewall Spacer Mask Formation for Semiconductor Uniformity

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Solution Overview

Problem

Traditional lithographic techniques face challenges in achieving planarity and uniformity of mask patterns during semiconductor device fabrication, leading to undesirable variations in fin structures and gate structures due to issues with mask formation.

Innovation Solution

A method involving the use of sacrificial spacing structures with protective hard masks, a sidewall spacer layer, and a protective material to selectively remove and recess the hard masks, resulting in sidewall spacers that provide a uniform mask pattern over the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional lithographic techniques are used for mask formation, then the fabrication process is simple, but the mask pattern lacks planarity and uniformity

Engineering Contradiction:

Improvemask pattern uniformityVSAvoidmask formation process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mask formation process is divided into multiple discrete steps: forming sacrificial structures, depositing sidewall spacer layer, selective removal to create sidewall spacers, depositing protective material, and selective etching. Each step builds upon the previous one to achieve the final uniform mask pattern, breaking down the complex process into manageable segments that collectively solve the uniformity problem.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Sacrificial structures are formed in advance with protective hard masks on their upper surfaces. The sidewall spacer layer is deposited conformally over these pre-formed structures before any removal occurs. This preliminary preparation ensures that when selective removal happens, the sidewall spacers are already in position to guide the formation of uniform mask elements.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 3:

Sidewall spacers act as intermediary structures that transfer the pattern from the sacrificial structures to the final mask. The protective material serves as another intermediary that protects certain areas during selective etching. These intermediary elements enable the transformation from non-uniform traditional masks to uniform self-aligned masks.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional mask formation is used, then the process steps are fewer, but variations in fin and gate structures occur

Engineering Contradiction:

Improveconsistency of fin and gate structuresVSAvoidmask formation process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective material is selectively applied to specific locations, and the sidewall spacer layer is selectively removed from certain areas while retained in others. This local differentiation ensures that etching occurs only where needed, protecting the fin and gate structures from unwanted variations while allowing precise pattern formation in critical areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The process changes the physical state and properties of materials at different stages: conformal deposition creates uniform thickness, selective removal changes material presence locally, and controlled etching modifies the structure with precision. These parameter changes at different stages ensure consistent fin and gate structure formation.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If conformal sidewall spacer layer is deposited and selectively removed, then uniform mask elements are achieved, but the process complexity increases

Engineering Contradiction:

Improvemask element height uniformityVSAvoidmask formation ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The sidewall spacer layer serves multiple functions: it forms the sidewall spacers through selective removal, defines the mask element positions, and guides the subsequent etching process. The protective hard masks on sacrificial structures self-align with the sidewall spacers, eliminating the need for additional alignment steps and simplifying the overall manufacturing despite the increased process steps.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Multiple functions are merged into single process steps: the conformal deposition of sidewall spacer layer simultaneously prepares for both sidewall spacer formation and future mask element definition. The selective removal step both exposes protective hard masks and creates sidewall spacers in one operation. This merging reduces the number of separate process steps needed.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8871651B1Mask formation processing

Publication Date: 2014.10.28 GLOBALFOUNDRIES US INC

AI summary

A mask for use in fabricating one or more semiconductor devices is fabricated by: providing sacrificial spacing structures disposed over a substrate structure, and including protective hard masks at upper surfaces of the spacing structures; disposing a sidewall spacer layer conformally over the sacrificial spacing structures; selectively removing the sidewall spacer layer from above the sacrificial spacing structures to expose the protective hard masks of the spacing structures, the selectively removing including leaving sidewall spacers along sidewalls of the sacrificial spacing structures; providing a protective material over the substrate structure; and removing the exposed protective hard masks from the sacrificial spacing structures, and thereafter, removing remaining sacrificial spacing structures and the protective material, leaving the sidewall spacers over the substrate structure as a mask.