Pre-endpoint techniques in photoresist etching
AssigneeLam Research Corporation
InventorsTaejoon Han, Xiaoqiang Yao
Life of this patent
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Abstract
A method for controlling a photoresist etch step in a plasma processing chamber is disclosed. The photoresist etch step being configured to etch back a photoresist layer deposited on a substrate surface to a thinner photoresist layer having predefined photoresist thickness. The method includes etching the photoresist layer using a plasma etch process and detecting interference patterns coming from the photoresist layer. The method further includes terminating the photoresist etch step when an analysis of the interference patterns indicates that the predefined photoresist thickness is achieved, whereby the predefined photoresist thickness is greater than zero.
Claims25
In a plasma processing chamber, a method for controlling a photoresist etch step, said photoresist etch step being configured to etch back a photoresist layer deposited on an underlying layer of a substrate surface to a thinner photoresist layer having predefined photoresist thickness above an interface between said photoresist layer and said underlying layer, said method comprising:
- etching said photoresist layer using a plasma etch process;
- detecting interference patterns coming from said photoresist layer;
- and
- terminating said photoresist etch step when an analysis of said interference patterns indicates that said predefined photoresist thickness is achieved, whereby said predefined photoresist thickness is greater than zero.
In a plasma processing chamber, a method for etching a photoresist layer, said photoresist layer being disposed on an underlying layer of a substrate, comprising:
- performing a first photoresist etch step for etching said photoresist layer using a first plasma etch recipe, said first photoresist etch step being configured to etch said photoresist layer down to a thinner photoresist layer having a predefined photoresist thickness above an interface between said photoresist layer and said underlying layer, said performing said first photoresist etch step includes detecting interference patterns coming from said photoresist layer during said first photoresist etch step and terminating said first photoresist etch step when an analysis of said interference patterns indicates that said predefined photoresist thickness is achieved, whereby said predefined photoresist thickness is greater than zero;
- and
- thereafter performing a second photoresist etch step for etching said thinner photoresist layer using a second plasma etch recipe different from said first etch recipe.
In a plasma processing chamber, a method for etching a photoresist layer, said photoresist layer being disposed on an underlying layer having at least a via disposed therein, photoresist material of said photoresist layer being present above a surface of said underlying layer and inside said via, comprising:
- performing a bulk etch step for etching said photoresist layer using a first plasma etch recipe, said bulk etch step being configured to etch said photoresist layer down to a thinner photoresist layer having a predefined photoresist thickness, said performing said bulk etch step includes detecting interference patterns coming from said photoresist layer during said bulk etch step and terminating said bulk etch step when an analysis of said interference patterns indicates that said predefined photoresist thickness is achieved, whereby said predefined photoresist thickness is greater than zero;
- and
- thereafter performing a recess etch step for etching said thinner photoresist layer using a second plasma etch recipe different from said first etch recipe, an etch rate of said bulk etch step being faster than an etch rate of said recess etch step, said recess etch step being configured to etch only a portion of said photoresist material disposed in said via, thereby leaving a column of photoresist material remaining in said via after said recess etch step.
Dependencies are inferred from the claim text.