Substrate Processing Method for Native Oxide Removal
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Solution Overview
Problem
Existing substrate processing methods fail to efficiently remove native oxide films from wafers without damaging protective silicon nitride films, leading to incomplete etching and reduced productivity due to temperature control limitations.
Innovation Solution
A substrate processing method involving the formation of a reaction layer using plasma and subsequent energy application to remove the native oxide film, while maintaining the integrity of the silicon nitride film, utilizing a CR processing technique that includes forming a reaction layer like ammonium fluorosilicate and sublimating it at controlled temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching methods are used to remove native oxide films, then etching speed is improved, but the silicon nitride protective film is damaged
Solution Approach 1:
The invention changes the chemical parameters of the etching process by using ammonium bifluoride solution with controlled concentration (0.1-10 wt%) and temperature (20-100°C). This chemical parameter adjustment enables selective etching of native oxide films while preserving the silicon nitride protective film, resolving the contradiction between etching speed and film integrity
Solution Approach 2:
The invention introduces an intermediary chemical substance (ammonium bifluoride) that acts as a selective etching agent. This intermediary selectively reacts with native oxide films through chemical interaction while being inert to silicon nitride films, thereby enabling fast etching without damaging the protective film
2Productivity
If temperature is increased to accelerate reaction layer removal, then etching efficiency is improved, but pattern shape control deteriorates
Solution Approach 1:
The invention implements dynamic temperature control during the etching process, adjusting temperature in real-time based on process requirements. The temperature is maintained within 20-100°C range, with optimization at specific stages: lower temperatures during reaction layer formation and higher temperatures during removal, enabling both high efficiency and precise pattern control
Solution Approach 2:
The etching process employs periodic temperature cycling with multiple stages: initial heating for reaction layer formation, followed by temperature adjustment for selective removal. This periodic temperature action allows the system to achieve both high etching efficiency and precise pattern shape control by optimizing conditions at each stage
3Manufacturing precision
If multiple processing steps are used to remove native oxide films, then etching completeness is improved, but processing time increases
Solution Approach 1:
The invention merges multiple separate processing steps (native oxide removal, reaction layer formation, and pattern definition) into a single integrated etching process using ammonium bifluoride solution. This consolidation achieves complete etching in one step without requiring sequential operations, thereby reducing total processing time while maintaining etching completeness
Solution Approach 2:
The ammonium bifluoride etching solution serves multiple functions simultaneously: it removes native oxide films, forms reaction layers, and defines patterns all in one process. This multi-functionality eliminates the need for separate processing steps, achieving complete etching while minimizing processing time
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 effectively removes native oxide films with higher etching rates than silicon or silicon nitride, improving productivity and precision by controlling etching amounts and pattern shapes, and reducing the time required for temperature adjustments between processing steps.
Implementation Method 1
forming a reaction layer on a surface layer of the substrate by plasma
Implementation Method 2
removing the reaction layer by applying energy to the substrate
Data Source
AI summary
A substrate processing method includes providing a processing target substrate having a pattern, forming a film on the substrate, forming a reaction layer on a surface layer of the substrate by plasma, and removing the reaction layer by applying energy to the substrate.