Gate Cap Protection Layer for Semiconductor Contact Etching

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Solution Overview

Problem

The existing methods for forming self-aligned contacts in semiconductor devices result in undesirable loss of protective gate cap layers and sidewall spacers, leading to increased complexity and difficulty in gate etching and spacer etching processes due to the need for additional thickness to compensate for material consumption during the contact etch process.

Innovation Solution

The method involves recessing the gate and spacer structures to form a spacer/gate cap recess, where a gate cap layer is formed with a thickness less than the recess depth, and a protection layer is applied on top, allowing for the removal of excess protection material while maintaining protection for the gate cap layer, thereby reducing material loss and process complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gate cap layer is made thicker to compensate for material consumption during contact etching, then the protective function is maintained, but the aspect ratio of contact openings increases and process complexity increases

Engineering Contradiction:

Improveprotective function of gate cap layerVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The gate cap layer is recessed before the contact etch process to pre-position it at a depth where it will be protected during subsequent etching operations. This preliminary action allows the gate cap layer to maintain its protective function without requiring excessive thickness, thereby reducing contact opening aspect ratio and simplifying the overall process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A spacer structure is introduced as an intermediary element between the gate cap layer and the contact etch process. The spacer structure protects the gate cap layer during contact formation, eliminating the need for the gate cap layer to be excessively thick. This mediator approach reduces both the aspect ratio and process complexity while maintaining protective functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of substance

If the gate cap layer thickness is increased to prevent material loss during contact etching, then the protective function is maintained, but the aspect ratio of contact openings increases

Engineering Contradiction:

Improvematerial loss of gate cap layerVSAvoidaspect ratio of contact openings

Core Design Contradiction:

Loss of substanceVSLength of stationary object

Solution Approach 1:

The gate cap layer is recessed to a predetermined depth before contact etching, positioning it where it will be protected by the spacer structure during the etch process. This preliminary positioning prevents material loss without requiring the gate cap layer to extend excessively high, thereby controlling the aspect ratio of contact openings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spacer structure serves as a protective intermediary during contact etching, preventing direct exposure and material loss of the gate cap layer. This intermediary protection mechanism eliminates the need for excessive gate cap layer thickness, thus maintaining acceptable aspect ratios for contact openings.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If additional thickness is added to the gate cap layer to compensate for contact etch consumption, then material loss is prevented, but etching process complexity increases

Engineering Contradiction:

Improvegate cap layer integrityVSAvoidetching process ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The gate cap layer is recessed to a specific depth before contact formation, pre-positioning it to avoid direct exposure during contact etching. This preliminary action maintains manufacturing precision by protecting the gate cap layer integrity without requiring complex multi-step etching processes to manage excessive thickness.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spacer structure acts as a protective intermediary during contact etching, simplifying the manufacturing process by eliminating the need for complex process steps to manage thick gate cap layers. This intermediary approach maintains gate cap layer integrity while improving ease of manufacture.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9263537B2Methods of forming a semiconductor device with a protected gate cap layer and the resulting device

Publication Date: 2016.02.16 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

One method disclosed herein includes forming first and second gate cap protection layers that encapsulate and protect a gate cap layer. A novel transistor device disclosed herein includes a gate structure positioned above a semiconductor substrate, a spacer structure positioned adjacent the gate structure, a layer of insulating material positioned above the substrate and around the spacer structure, a gate cap layer positioned above the gate structure and the spacer structure, and a gate cap protection material that encapsulates the gate cap layer, wherein portions of the gate cap protection material are positioned between the gate cap layer and the gate structure, the spacer structure and the layer of insulating material.