Polysilicon Wet Etching Selectivity via Sugar Alcohol Additives
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Solution Overview
Problem
Current semiconductor fabrication processes face challenges in reducing process margins while maintaining high integration density and performance, particularly in the wet etching of polysilicon layers, which can lead to difficulties in fabricating semiconductor devices with high yield and quality.
Innovation Solution
A wet etching method using an etchant containing a basic compound such as ammonium hydroxide or tetraalkyl ammonium hydroxide, combined with sugar alcohols like Sorbitol and a specific amine compound, is employed to effectively etch polysilicon layers, ensuring selective etching of sacrificial gate patterns without damaging source/drain regions, thereby improving the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching methods are used to etch polysilicon layers, then the etching process can be performed, but source/drain regions are damaged and manufacturing yield decreases
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by adding sugar alcohol compounds (sorbitol, mannitol, xylitol, etc.) to conventional basic etchants. This parameter change enables selective etching of polysilicon while protecting source/drain regions, resolving the contradiction between etching effectiveness and region integrity
Solution Approach 2:
Sugar alcohol compounds act as intermediary substances that mediate between the etchant and the semiconductor structure. These intermediaries provide selective protection to source/drain regions during etching, allowing precise control over which materials are removed while preserving sensitive regions
2Productivity
If process margin is reduced to achieve higher integration density, then device performance improves, but fabrication difficulty increases and yield decreases
Solution Approach 1:
By changing the chemical parameters of the etching process through sugar alcohol additives, the patent achieves better process control and selectivity. This enables manufacturers to work with tighter process margins required for high integration density while maintaining fabrication ease through improved process window
3Manufacturing precision
If etching selectivity is increased to protect source/drain regions, then region integrity improves, but etching rate may decrease
Solution Approach 1:
The patent optimizes the concentration ratios of sugar alcohols to basic compounds in the etchant, achieving a balance where selectivity is enhanced through chemical modification while maintaining practical etching rates by adjusting compositional parameters
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 enhances the etching process by maintaining the integrity of source/drain regions, reducing defects, and increasing the yield of semiconductor devices by using a controlled etchant composition that balances etch rate and selectivity.
Implementation Method 1
supplying an etchant on an etch-target layer to etch the etch-target layer in a wet etch manner
Implementation Method 2
The etchant may contain a basic compound and a sugar alcohol... capable of selectively removing a polysilicon layer
Data Source
AI summary
The present disclosure relates to an etchant, a method of making an etchant, an etching method and a method of fabricating a semiconductor device using the same. The etching method includes supplying an etchant on an etch-target layer to etch the etch-target layer in a wet etch manner. The etchant contains a basic compound and a sugar alcohol, and the basic compound contains ammonium hydroxide or tetraalkyl ammonium hydroxide. In the etchant, the sugar alcohol has 0.1 to 10 parts by weight for every 100 parts by weight of the basic compound.