Electric-Field Directed Post-Exposure Bake for Double-Patterning
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in effectively controlling acid diffusion in chemically amplified resists during Double-Patterning (D-P) sequences, leading to variations in Critical Dimension (CD) and issues like sidewall and scumming problems.
Innovation Solution
The implementation of Electric-Field Enhancement Layers (E-FELs) using anti-reflective coating, optically-activated, and non-optically-activated layers, controlled by DC, AC, RF, microwave, UV, or IR signals, to minimize acid diffusion and reduce the number of etching steps by creating latent images and enhancing solubility through electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional post exposure bake (PEB) is used to impart selective solubility to photoresist, then the photoresist can be dissolved in aqueous base, but lateral acid diffusion occurs causing CD variations
Solution Approach 1:
An electric field is introduced as an intermediary between the PEB step and the development step. The electric field acts on charged species within the photoresist to direct acid diffusion, preventing lateral spread while maintaining the solubility switch. This mediator (electric field) resolves the contradiction by enabling selective solubility without the harmful lateral diffusion that occurs in conventional PEB processes.
Solution Approach 2:
The invention changes the physical parameter of acid diffusion by applying an external electric field during or after PEB. By controlling the electric field strength and direction, the diffusion behavior of acid species is fundamentally altered from random lateral diffusion to directed vertical or controlled movement, thereby maintaining CD precision while still achieving the solubility change needed for pattern transfer.
2Productivity
If multiple etching steps are used to achieve double-patterning, then pattern density is improved, but process complexity and time increase
Solution Approach 1:
The invention replaces the mechanical/chemical approach of multiple sequential etching steps with an electric field-based approach. Instead of physically removing material multiple times, the electric field directs acid diffusion to create the double-patterning effect in a single exposure and development sequence, thereby reducing process complexity while maintaining high pattern density.
Solution Approach 2:
The electric field is applied during or immediately after the PEB step to pre-direct acid diffusion before the development process. This preliminary action of controlling acid movement allows the subsequent development step to directly produce the double-patterning result without requiring multiple etching cycles, thus simplifying the overall process flow.
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
E-FELs effectively control acid diffusion, minimize sidewall and scumming issues, and reduce the number of etching steps, thereby improving CD control and process precision in Double-Patterning sequences.
Implementation Method 1
Using electric-field directed post-exposure bake for double-patterning (D-P)
Implementation Method 2
optically-activated layers
Data Source
AI summary
The invention provides a method of processing a substrate using Double-Patterning (D-P) processing sequences and Electric-Field Enhanced Layers (E-FELs). The D-P processing sequences and E-FELs can be used to create lines, trenches, vias, spacers, contacts, and gate structures using a minimum number of etch processes.