Convection optimization for mixed feature electroplating
AssigneeLam Research Corporation
InventorsGabriel Hay Graham, Lee Peng Chua, Boon Kang Ong
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Abstract
Various embodiments herein relate to methods and apparatus for electroplating material onto substrates. Often the substrate is a semiconductor substrate. Various techniques described herein utilize a number of different electroplating stages, where the convection conditions vary between the different electroplating stages. In many cases, at least one ultra-low convection stage is used. The ultra-low convection stage may be paired with an initial stage and a final stage that have higher convection conditions. By controlling the convection conditions as described herein, very uniform plating results can be achieved, even when differently sized and/or shaped features are provided on a single substrate.
Claims19
A method of electroplating material onto a substrate, the method comprising:
- providing the substrate to an electroplating apparatus, wherein the substrate is a semiconductor substrate comprising a plurality of features recessed into a surface of the substrate;
- immersing the substrate in electrolyte in the electroplating apparatus;
- in a first stage, electroplating the material on to the substrate while flowing electrolyte within or through the electroplating apparatus to provide moderate or high convection conditions at the surface of the substrate;
- switching from the first stage to a second stage when a first switching condition is met;
- in the second stage, electroplating the material onto the substrate while flowing electrolyte within or through the electroplating apparatus to provide ultra-low convection conditions at the surface of the substrate,
- wherein at the ultra-low convection conditions, electrolyte flow proximate the surface of the substrate is laminar, and mass transport of metal ions in the electrolyte within the features is dominated by diffusion rather than convection over at least 75% of a depth of the features, and
- wherein the moderate or high convection conditions provide greater convection to the surface of the substrate compared to the ultra-low convection conditions;
- and
- removing the substrate from the electrolyte.
An apparatus for electroplating material onto a substrate, the apparatus comprising:
- an electroplating chamber;
- a substrate support;
- and
- a controller configured to:
- cause a substrate to be provided to an electroplating apparatus, wherein the substrate is a semiconductor substrate comprising a plurality of features recessed into a surface of the substrate;
- cause the substrate to be immersed in electrolyte in the electroplating apparatus;
- in a first stage, cause the material to be electroplated on to the substrate while flowing electrolyte within or through the electroplating apparatus to provide moderate or high convection conditions at the surface of the substrate;
- switch from the first stage to a second stage when a first switching condition is met;
- in the second stage, causing the material to be electroplated onto the substrate while flowing electrolyte within or through the electroplating apparatus to provide ultra-low convection conditions at the surface of the substrate,
- wherein at the ultra-low convection conditions, electrolyte flow proximate the surface of the substrate is laminar, and mass transport of metal ions in the electrolyte within the features is dominated by diffusion rather than convection over at least 75% of a depth of the features, and
- wherein the moderate or high convection conditions provide greater convection to the surface of the substrate compared to the ultra-low convection conditions;
- and
- causing the substrate to be removed from the electrolyte.
Dependencies are inferred from the claim text.