UV Pre-treatment Gas Generation for Substrate Cleaning
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Solution Overview
Problem
Current substrate cleaning processes in semiconductor manufacturing, particularly for low-k dielectrics, face challenges in effectively removing post-etch polymers without increasing the k-value or damaging the underlying dielectric, and require expensive equipment and complex gas delivery systems.
Innovation Solution
A method and system that optimize pre-treatment operating variables such as UV dose, substrate temperature, oxygen and ozone partial pressures, and total pressure using metrology measurements to deliver a pre-treatment gas comprising oxygen and/or ozone, generating oxygen radicals for partial cleaning, followed by a wet clean process to maintain k-value within acceptable ranges and simplify hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 185 nm radiation is used for pre-treatment, then polymer removal ability is improved, but k-value of the dielectric increases and damage occurs
Solution Approach 1:
The patent applies partial action by using only 254 nm UV radiation without 185 nm radiation, achieving sufficient polymer removal through optimized oxygen partial pressure and UV dose without causing dielectric damage. The cleaning is intentionally set at less than 100% removal in pre-treatment to preserve the dielectric.
Solution Approach 2:
The patent changes the radiation wavelength parameter from including 185 nm to exclusively 254 nm, and adjusts oxygen partial pressure parameters to compensate, achieving effective cleaning without dielectric damage that would occur with 185 nm radiation.
2Manufacturing precision
If ozone generating Hg lamps are used, then pre-treatment performance is improved, but equipment cost and complexity increase
Solution Approach 1:
The patent extracts the harmful 185 nm radiation component from the UV lamp output, using only the beneficial 254 nm wavelength. This is achieved by selecting lamps that naturally emit only at 254 nm or using optical filters to block 185 nm radiation, thereby eliminating ozone generation while maintaining cleaning effectiveness.
Solution Approach 2:
The patent uses standard 254 nm UV lamps that are simpler and less expensive than ozone-generating lamps, accepting that these are conventional, well-understood components rather than requiring specialized expensive equipment.
3Manufacturing precision
If excimer lamps or lasers are used for cleaning, then organic material degradation is achieved, but processing cost and hardware complexity increase
Solution Approach 1:
The patent replaces expensive excimer lamps and lasers with conventional 254 nm UV lamps, which are standard, inexpensive components. The process achieves effective organic material degradation through the combination of 254 nm UV radiation with optimized oxygen partial pressure, eliminating the need for costly specialized equipment.
Solution Approach 2:
The patent changes the approach from using high-energy excimer radiation or lasers to using lower-energy 254 nm UV radiation combined with controlled oxygen parameters, achieving comparable or superior results at lower cost and complexity.
4Productivity
If complete cleaning is performed in pre-treatment, then polymer removal is maximized, but k-value change exceeds acceptable range
Solution Approach 1:
The patent deliberately applies partial action by setting the pre-treatment cleaning level at less than 100% polymer removal. This partial cleaning is sufficient to prepare the surface for effective wet cleaning while maintaining the dielectric k-value within acceptable ranges, avoiding the damage that would result from complete removal.
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 approach ensures effective substrate cleaning with reduced k-value change and damage, while reducing the complexity and cost of the cleaning process, and simplifying the hardware system by using standard air to generate sufficient oxygen and ozone radicals, thereby shortening processing times and reducing equipment needs.
Implementation Method 1
A pre-treatment gas comprising oxygen and/or ozone is delivered onto a surface of the substrate and irradiated with a UV device, generating oxygen radicals
Implementation Method 2
The 185 nm radiation has sufficient energy to break-up oxygen to form oxygen atoms which in turn react with oxygen to form ozone
Implementation Method 3
The 254 nm radiation is absorbed by ozone to generate oxygen atoms
Implementation Method 4
Gas including the oxygen radical is passed along the surface of the substrate to cause degeneration of the organic material thereon
Data Source
AI summary
Provided is a method and system for cleaning a substrate with a cleaning system comprising a pre-treatment system and a wet clean system. One or more objectives for the pre-treatment system are selected and two or more pre-treatment operating variables including UV dose, substrate temperature, oxygen partial pressure, oxygen and ozone partial pressure, and/or total pressure, are optimized to meet the pre-treatment objectives, using metrology measurements. The substrate includes a layer to be cleaned and an underlying dielectric layer having a k-value. A pre-treatment gas comprising oxygen and/or ozone is delivered onto a surface of the substrate and irradiated with a UV device, generating oxygen radicals. Cleaning of the substrate in the pre-treatment process is set at less than 100% in order to ensure the change in k-value of the substrate is within a set range for the substrate application.