Substrate Residue Removal Using UV and Alkaline Wet Cleaning
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is the efficient removal of residues after dry etching while minimizing damage to the metal layer and hard mask, which affects electrical characteristics due to residue-induced leakage and increased wiring resistance.
Innovation Solution
A substrate processing method involving ultraviolet ray irradiation followed by alkaline-based wet processing to remove residues containing metal oxides and organic metallic substances, using a pH between 7 and 14, and controlling the atmosphere to reduce physical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is performed to pattern the metal layer, then the metal layer can be precisely patterned, but residue is generated on the substrate surface
Solution Approach 1:
The patent converts the harmful residue generated by dry etching into a removable substance by utilizing ultraviolet irradiation to modify the residue's chemical structure, making it more susceptible to removal by alkaline solutions. The residue, initially a harmful byproduct, becomes a target for selective removal through photochemical modification.
Solution Approach 2:
The patent introduces ultraviolet irradiation as an intermediary step between dry etching and wet cleaning. This intermediary process modifies the residue's properties without directly removing it, enabling subsequent easy removal by alkaline solutions while preserving the metal layer and hard mask.
2Object-generated harmful factors
If cleaning process is performed to remove residue, then residue can be removed, but damage to hard mask and wiring occurs
Solution Approach 1:
The patent changes the chemical parameters of the cleaning process by using alkaline solutions with controlled pH (7-14) instead of traditional strong acids or bases. This parameter change enables effective residue removal while minimizing damage to the metal layer and hard mask, as the alkaline environment is less aggressive toward these materials.
Solution Approach 2:
The patent applies ultraviolet irradiation as a preliminary action before wet cleaning. This pre-treatment modifies the residue's chemical structure, making it more easily removable by the subsequent alkaline cleaning process, thereby reducing the aggressiveness and potential damage of the cleaning step.
3Productivity
If strong cleaning agents are used to remove residue efficiently, then residue removal performance improves, but damage to metal layer and hard mask increases
Solution Approach 1:
The patent changes the pH parameter of the cleaning solution to the alkaline range (7-14), which provides sufficient cleaning power to remove UV-modified residue effectively while being less damaging to the metal layer and hard mask compared to strong acidic or highly alkaline traditional cleaners.
Solution Approach 2:
The patent uses ultraviolet irradiation as an intermediary that pre-modifies the residue, reducing the strength required for the cleaning agent. This allows the use of milder alkaline solutions that maintain high removal efficiency without causing excessive damage to sensitive structures.
4Object-generated harmful factors
If film reduction occurs to remove residue, then residue can be removed, but wiring resistance increases
Solution Approach 1:
The patent introduces ultraviolet irradiation as an intermediary that selectively modifies the residue's chemical bonds without affecting the metal layer. This enables subsequent removal of the modified residue through chemical dissolution rather than physical removal, preventing film reduction and maintaining wiring integrity and electrical characteristics.
Solution Approach 2:
The patent converts the residue's chemical structure through UV irradiation, transforming it from a tightly bonded etching byproduct into a more labile substance that can be removed by alkaline dissolution. This conversion allows residue removal through chemical means rather than physical removal, avoiding film reduction and preserving electrical properties.
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
Effectively removes residues without damaging the metal layer or hard mask, reducing the risk of leakage and resistance, and maintaining the integrity of the semiconductor device.
Implementation Method 1
a step of irradiating an ultraviolet ray to a residue generated on the surface of the substrate by the dry etching, the residue containing one or more types of metal oxide, metallic halide, and an organic metallic substance
Implementation Method 2
a step of removing the residue from the substrate by wet processing in which a residue removing liquid having a pH (hydrogen ion exponent) of not less than 7 and not more than 14 is supplied to the surface of the substrate after irradiation of the ultraviolet ray
Data Source
AI summary
A substrate processing method processes a substrate having a metal layer and a hard mask that is laminated on the metal layer on a surface. This method includes a step of dry etching and patterning the metal layer exposed from the hard mask, a step of irradiating an ultraviolet ray to a residue generated on the surface of the substrate by the dry etching, and a step of removing the residue from the substrate by wet processing in which a residue removing liquid having a pH (hydrogen ion exponent) of not less than 7 and not more than 14 is supplied to the surface of the substrate after irradiation of the ultraviolet ray. The residue contains one or more types of metal oxide, metallic halide, and an organic metallic substance each of which contains an element of a main constituent metal of the metal layer.