HF-Alcohol Gas Mixture for HAR Pattern Collapse Prevention
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Solution Overview
Problem
Current methods for preventing pattern collapse and repairing high aspect ratio structures during substrate processing are costly and inefficient, as they often require expensive equipment and materials like supercritical CO2, surface modification, or plasma etching, which are not suitable for all aspect ratios and can cause material loss or damage.
Innovation Solution
A gas mixture comprising hydrogen fluoride gas, alcohol vapor, and an additive, such as ammonia or pyridine, is used to treat substrates, promoting bifluorine formation and increasing etch selectivity, thereby preventing pattern collapse and repairing collapsed structures without the need for expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supercritical CO2 is used to dry the substrate, then pattern collapse is reduced, but cost increases and implementation issues arise
Solution Approach 1:
The patent replaces expensive supercritical CO2 drying with a disposable liquid composition (containing HF, alcohol, and additive) that is applied, allowed to evaporate, and discarded. This single-use liquid approach eliminates the need for costly supercritical fluid equipment while achieving the same pattern collapse prevention effect through controlled evaporation and selective etching.
Solution Approach 2:
The patent changes the physical state and composition parameters by using a liquid solution at atmospheric pressure instead of supercritical CO2. The liquid composition contains HF (0.1-10%), alcohol (90-99.9%), and additive (0.01-1%), which upon evaporation leaves residues that prevent stiction and pattern collapse, achieving the same protective effect as supercritical drying but through chemical parameter changes rather than extreme pressure/temperature conditions.
2Reliability
If surface modification is performed to prevent stiction, then pattern collapse is reduced, but material loss occurs and cost increases
Solution Approach 1:
The patent applies a preliminary protective action by depositing a thin residue layer of the liquid composition (after alcohol evaporation) on the substrate surface before drying. This residue layer acts as a preliminary protective coating that prevents stiction and pattern collapse during subsequent drying, eliminating the need for permanent surface modification that would require material removal.
Solution Approach 2:
The patent introduces an intermediary substance (the additive and HF residue) that mediates between the substrate and the drying process. This intermediary layer prevents direct contact and stiction between HAR structures during drying, avoiding the need to permanently modify or remove substrate material while still achieving stiction prevention.
3Reliability
If vacuum equipment is used for HF vapor etching, then HAR structures can be treated, but equipment cost increases and wet cleaning capability is lost
Solution Approach 1:
The patent creates a universal liquid composition that performs multiple functions: it etches oxide selectively (HF action), prevents stiction (alcohol and additive action), and enables wet cleaning capability. This single liquid composition can be used in standard wet cleaning equipment without requiring expensive vacuum systems, making the equipment versatile for both cleaning and HAR structure treatment.
Solution Approach 2:
The patent replaces the vacuum mechanical system with a liquid-based chemical system. Instead of using vacuum equipment to deliver HF vapor, the patent uses liquid HF-containing composition delivered through standard liquid delivery mechanisms. This substitution eliminates the need for vacuum equipment while achieving the same oxide treatment effect through liquid-phase chemistry rather than vapor-phase physics.
4Productivity
If boiling IPA is used to dry the substrate, then drying is achieved, but pattern collapse occurs for high aspect ratio structures
Solution Approach 1:
The patent uses a composite liquid composition containing multiple components: HF (for selective oxide etching), alcohol (for drying and stiction prevention), and additive (for enhanced protection). This composite formulation works synergistically - the HF removes problematic oxide bridges, the alcohol provides rapid drying, and the additive enhances stiction prevention, achieving both fast drying and pattern collapse prevention simultaneously.
Solution Approach 2:
The patent converts the potentially harmful effect of rapid evaporation (which causes pattern collapse) into a beneficial effect. By controlling the composition to evaporate in a specific sequence (alcohol first, then HF and additive residues remain), the rapid evaporation that would normally cause collapse instead leaves behind a protective residue layer that prevents stiction, turning the harmful rapid drying effect into a protective mechanism.
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
The gas mixture effectively prevents pattern collapse and repairs high aspect ratio structures by increasing etch selectivity and reducing material loss, providing a cost-effective alternative to existing methods that can be used at atmospheric pressure in a single hardware device.
Implementation Method 1
promoting bifluorine formation and increasing etch selectivity
Implementation Method 2
a vapor of alcohol
Implementation Method 3
increasing etch selectivity, thereby preventing pattern collapse and repairing collapsed structures
Data Source
AI summary
A gas mixture for treating a substrate in a substrate processing system includes hydrogen fluoride gas, a vapor of an alcohol, an additive consisting of a base, and a carrier gas. The gas mixture can be used to treat high aspect ratio (HAR) structures arranged on a surface of a substrate. A surface of the substrate may be spin rinsed using a first rinsing liquid. The first rinsing liquid is spun off from the surface of the substrate. The gas mixture is directed onto the surface of the substrate after the first rinsing liquid is dispensed.