Back to results
US 8,241,991 B2Granted
Method for forming interconnect structure having airgap
AssigneeASM Japan K.K.
InventorsJulian J. Hsieh, Nobuyoshi Kobayashi, Akira Shimizu, Kiyohiro Matsushita, Atsuki Fukazawa
Life of this patent
Estimating the term…
Abstract
A method for forming an interconnect structure with airgaps, includes: providing a structure having a trench formed on a substrate; depositing a spacer oxide layer on sidewalls of the trench as sidewall spacers by plasma enhanced atomic layer deposition; filling the trench having the sidewall spacers with copper; removing the sidewall spacers to form an airgap structure; and encapsulating the airgap structure, wherein airgaps are formed between the filled copper and the sidewalls of the trench.
Claims13
A method for forming an interconnect structure with airgaps, comprising:
- forming photoresist patterns at a pitch of 2X on a hard mask, each photoresist pattern having a width of X;
- etching the hard mask between adjacent photoresist patterns, each etched portion having a width of (X−2Y);
- etching the hard mask underneath each photoresist pattern, each etched portion having a width of (X−2Y), thereby forming hard mask patterns at a pitch of X, each hard mask pattern having a width of 2Y;
- etching a layer underneath the hard mask patterns, thereby providing a structure having trenches formed on a substrate;
- depositing a spacer oxide layer on sidewalls of each trench as sidewall spacers so that the sidewall spacers-provided trenches each have a width of X/2 and are distanced at an interval of X/2;
- filling the trenches having the sidewall spacers with copper, thereby forming copper patterns at a pitch of X;
- removing the sidewall spacers to form an airgap structure;
- and
- encapsulating the airgap structure, wherein airgaps are formed between the copper patterns, where the copper patterns each have a width of X/2 and are distanced at an interval of X/2, and the airgaps each have a width of (X/2−2Y)/2 or less,
- wherein X and Y are selected to achieve a targeted dielectric constant of the encapsulated airgap structure between the copper patterns.
7 more elements
A method for forming an interconnect structure with airgaps, comprising
- providing a structure having a trench formed on a substrate;
- depositing a spacer oxide layer on sidewalls of the trench as sidewall spacers;
- filling the trench having the sidewall spacers with copper;
- removing the sidewall spacers to form an airgap structure;
- and
- encapsulating the airgap structure, wherein airgaps are formed between the filled copper and the sidewalls of the trench,
- wherein the structure having the trench on the substrate:
- is a layered structure comprising a diffusion barrier layer, a low-k layer, and the hard mask formed in this layering order on the substrate, wherein the trench penetrates the hard mask, the low-k layer, and the diffusion barrier layer,
- wherein the step of providing the structure comprises:
- forming a photoresist pattern on the hard mask;
- depositing an oxide spacer on the photoresist and an area of the hard mask uncovered by the photoresist, by PEALD at a temperature of 400° C. or lower;
- etching the oxide spacer by a thickness of the oxide spacer in a thickness direction, thereby leaving a sidewall portion of the oxide spacer deposited on sidewalls of the photoresist;
- etching an area of the hard mask exposed after the etching of the oxide spacer, followed by removing the sidewall portion of the oxide spacer and the photoresist to obtain a patterned hard mask and an exposed portion of the low-k layer;
- forming a second photoresist pattern on the exposed portion of the low-k layer and a part of the patterned hard mask;
- depositing a second oxide spacer on the second photoresist and an area of the patterned hard mask uncovered by the second photoresist, by PEALD at a temperature of 400° C. or lower;
- etching the second oxide spacer by a thickness of the second spacer in a thickness direction, thereby leaving a sidewall portion of the second oxide spacer deposited on sidewalls of the second photoresist;
- etching an area of the patterned hard mask exposed after the etching of the second oxide spacer, followed by removing the sidewall portion of the second oxide spacer and the second photoresist to obtain a second patterned hard mask and an exposed portion of the low-k layer;
- and
- etching the low-k layer and the diffusion barrier layer using the second patterned hard mask.
16 more elements
Dependencies are inferred from the claim text.