Tungsten Silicide Gate Cleaning for Semiconductor Yield
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Solution Overview
Problem
Conventional cleaning processes for semiconductor devices, particularly those using plasma-type reoxidation, fail to adequately restore tungsten silicide structures, leading to bowing defects and residual contaminants that affect manufacturing yield and reliability.
Innovation Solution
A two-stage cleaning process utilizing a first cleaning solution of ammonium hydroxide, hydrogen peroxide, and deionized water, followed by a second cleaning solution containing ozone water or hydrogen fluoride, to effectively remove contaminants without significant consumption of the conductive structures, combined with a plasma-type reoxidation process to restore the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a general cleaning process using ammonium peroxide mixture or sulfuric peroxide mixture is performed, then contaminants are removed, but conductive structures react with the cleaning solution and are damaged or consumed
Solution Approach 1:
The cleaning process is divided into two distinct stages: first using ammonium peroxide mixture to remove organic contaminants, then using sulfuric peroxide mixture to remove inorganic contaminants. This segmentation allows each cleaning solution to target specific contaminant types while minimizing overall damage to conductive structures compared to using a single aggressive cleaner
Solution Approach 2:
The invention changes the chemical parameters of the cleaning solution by sequentially using two different compositions with distinct properties. The first solution (ammonium peroxide) has different chemical characteristics than the second (sulfuric peroxide), allowing progressive cleaning that adapts to different contaminant types and reduces cumulative damage to tungsten silicide structures
2Reliability
If the amount of cleaning solution is decreased to minimize chemical reaction, then conductive structures are better preserved, but contaminants are not sufficiently removed
Solution Approach 1:
The cleaning process maintains continuous useful action through two sequential cleaning steps rather than a single prolonged exposure. Each step uses a different cleaning solution composition to continuously address different types of contaminants, ensuring thorough cleaning while limiting the time each structure is exposed to any single chemical environment
Solution Approach 2:
By changing the chemical composition parameters between two cleaning stages, the process achieves comprehensive contaminant removal without requiring excessive amounts of any single cleaning solution, thus minimizing total chemical damage while maintaining cleaning effectiveness
3Productivity
If plasma-type reoxidation process is used, then reoxidation is performed faster, but bowing defect is formed on sidewall of gate electrode because tungsten silicide does not adequately expand
Solution Approach 1:
The cleaning process is performed as a preliminary action before reoxidation, ensuring that all contaminants are completely removed. This preliminary cleaning prevents contamination-related defects during subsequent reoxidation, allowing the use of plasma-type reoxidation for faster processing without compromising final structure quality
Solution Approach 2:
The invention changes the approach by optimizing the cleaning parameters (using two-stage process) to enable the use of plasma-type reoxidation. The thorough cleaning prepared by the two-stage process allows plasma reoxidation to proceed without contamination interference, achieving both speed and quality
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 two-stage cleaning process ensures thorough removal of contaminants while minimizing damage to the semiconductor device, resulting in improved manufacturing yield and reliability by maintaining the integrity and shape of the conductive structures during the reoxidation process.
Implementation Method 1
cleaning the device with a first cleaning solution. In some embodiments the first cleaning solution includes a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2) and deionized (DI) water
Implementation Method 2
cleaning the device with a second cleaning solution. In some embodiments the second cleaning solution includes ozone (O3) water
Implementation Method 3
a plasma-type reoxidation process has been used as an alternative to a conventional furnace-type reoxidation process
Data Source
AI summary
The present invention provides methods of cleaning a semiconductor device by removing contaminants, such as particles and/or etching by-products, from a structure of a semiconductor device using a first cleaning solution including a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2) and deionized (DI) water, and a second cleaning solution including ozone (O3) water. The present invention also provides methods of manufacturing a semiconductor device using these methods of cleaning the semiconductor device.