Source/Drain Contact Etching for Platinum Residue Removal
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in safely and effectively removing platinum residues during the formation of nickel platinum silicide, as existing etchant chemistries like aqua regia are hazardous and sulfuric peroxide mixtures fail to provide adequate cleaning without damaging SiN spacers.
Innovation Solution
The use of specific etchant chemistries such as hydrochloric acid (HCl) and ozone (HOM solution) or perchloric acid with an oxidation potential above 1.4V for selective etching of platinum residues, which efficiently removes nickel and platinum without damaging contact spacers or SiN layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aqua regia is used to remove platinum residues, then removal efficiency is improved, but safety hazards increase due to extreme corrosion
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by using sulfuric acid with controlled concentration (e.g., 30% sulfuric acid) instead of aqua regia, and controls the etching temperature and time parameters to achieve effective platinum removal while reducing harmful corrosion effects
Solution Approach 2:
The patent employs a disposable etching solution system where the etchant is used in controlled amounts and then discarded after a single use, ensuring that hazardous chemicals do not accumulate and can be properly disposed of, reducing long-term safety hazards while maintaining effective platinum removal
2Productivity
If sulfuric peroxide mixture is used to etch platinum, then cleaning performance is improved, but contact spacer integrity deteriorates due to excessive etching
Solution Approach 1:
The patent modifies the etching parameters by using sulfuric acid at specific concentrations and controlling the etching time to be sufficient for platinum removal but limited enough to prevent contact spacer damage, achieving a balance between cleaning performance and structural integrity
Solution Approach 2:
The patent applies etching action that is sufficient for the intended purpose (platinum removal) but controlled to avoid excessive etching that would damage the contact spacer, using optimized etching time and concentration to achieve partial action that stops at the desired endpoint
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 method ensures the safe and complete removal of unreacted metal residues while preserving the integrity of the semiconductor device's components, improving the manufacturing process by enhancing the removal efficiency of platinum and nickel without compromising the structure.
Implementation Method 1
removing the metallic residues by using a wet etching process, wherein the spacer of the dielectric structure remains substantially intact
Data Source
AI summary
A method of forming a semiconductor device includes forming an epitaxial source/drain (S/D) structure adjacent to a gate structure; forming a dielectric structure over the gate and epitaxial S/D structures; forming a trench in the dielectric structure to accessibly expose a portion of the epitaxial S/D structure; forming a contact feature from the portion of the epitaxial S/D structure within the trench; and forming a S/D contact in the trench to be in contact with the contact feature overlying the epitaxial S/D structure. Forming the contact feature includes forming a metallic layer in the trench; performing a thermal process on the metallic layer to form the contact feature, where after the thermal process, metallic residues remain on a sidewall of a spacer of the dielectric structure in the trench; and removing the metallic residues by using a wet etching process, wherein the spacer of the dielectric structure remains substantially intact.