Semiconductor Plug Structure with Hard Mask Etch Stop

Solution Overview

Problem

In semiconductor fabrication, the etching process for forming vertical connections can lead to over-etching of inter-dielectric layers, resulting in a 'tiger-tooth' structure at the edge of upper-level plugs, which compromises the quality of the semiconductor device.

Innovation Solution

A method involving the formation of a dishing in the first inter-dielectric layer, followed by a hard mask layer that serves as an etching stop, and subsequent formation of a second plug structure with an edge portion extending on the hard mask layer, effectively preventing over-etching and reducing the occurrence of tiger-tooth structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the etching process is used to form via openings in the inter-dielectric layer, then the vertical connection between levels is achieved, but the inter-dielectric layer at the lower level is over-etched, causing an indent structure (tiger-tooth) to form

Engineering Contradiction:

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

A hard mask layer is introduced as an intermediary between the upper and lower inter-dielectric layers. This hard mask layer serves as an etching stop layer that prevents the etching process from damaging the lower inter-dielectric layer, thereby eliminating the tiger-tooth structure while still allowing via openings to be formed in the upper layer

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The hard mask layer is formed in advance before the via opening etching process. By preparing this protective layer beforehand, the patent prevents over-etching from occurring during the subsequent etching step, thus avoiding the formation of harmful indent structures

Inventive Principle:

Principle #10Preliminary action

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 approach enhances the quality of semiconductor devices by minimizing the formation of tiger-tooth structures, ensuring precise and reliable vertical connections between different levels of the semiconductor device.

Implementation Method 1

performing a polishing process over the first inter-dielectric layer to have a dishing on top

Methodology Applied

Scientific EffectMechanical polishing: Abrasion

Implementation Method 2

the hard mask layer serves as an etching stop layer, when the second inter-dielectric layer is patterned to have an opening to expose the first plug structure

Methodology Applied

Scientific EffectEtching stop:

Data Source

PatentUS10109525B1Fabrication method and structure of semiconductor device with contact and plug

Publication Date: 2018.10.23

AI summary

A method for fabricating a semiconductor device is provided including providing a substrate, on which a plurality of elements is formed. A first inter-dielectric layer is formed over the substrate, covering the elements. A first plug structure is formed in the first inter-dielectric layer, including performing a polishing process over the first inter-dielectric layer to have a dishing on top and extending from a sidewall of the first plug structure. A hard mask layer is formed to fill the dishing. A second inter-dielectric layer is formed over the hard mask layer. A second plug structure is formed in the second inter-dielectric layer to electrically contact the first plug structure, wherein the second plug structure has at least an edge portion extending on the hard mask layer.