Polysilicon Electrode Structure for Low Resistance and Impurity Control

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Solution Overview

Problem

As semiconductor devices become highly integrated, there is a need for electrode structures with low resistance and low reactivity with other material layers, while also preventing impurities from diffusing into semiconductor substrates.

Innovation Solution

The electrode structure includes a first polysilicon layer doped with resistance adjustment impurities, a second polysilicon layer for adjusting grains doped with grain adjustment impurities such as carbon, nitrogen, or oxygen, an ohmic metal layer, a barrier metal layer, and a metal layer, which helps in reducing the thickness of the ohmic metal layer and inhibiting impurity diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single polysilicon layer is used in the electrode structure, then the manufacturing process is simple, but the resistance cannot be effectively controlled and impurity diffusion cannot be prevented

Engineering Contradiction:

Improveresistance control and impurity diffusion preventionVSAvoidelectrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrode structure is divided into multiple polysilicon layers with distinct functions: a first polysilicon layer for resistance control through doping, and a second polysilicon layer for preventing impurity diffusion. This segmentation allows each layer to independently address specific requirements without compromising the other, resolving the contradiction between reliability and structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrode structure employs a composite configuration of multiple polysilicon layers with different doping characteristics. The first polysilicon layer contains doping impurities for resistance adjustment, while the second polysilicon layer serves as a barrier layer. This composite structure achieves both resistance control and impurity diffusion prevention simultaneously.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the thickness of the ohmic metal layer is reduced to improve device integration, then the device size decreases, but the manufacturing process flexibility and control are reduced

Engineering Contradiction:

Improvedevice integration densityVSAvoidmanufacturing process flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The second polysilicon layer acts as an intermediary barrier between the first polysilicon layer and the ohmic metal layer. This intermediate layer prevents direct interaction and potential diffusion between the metal and underlying polysilicon, allowing the ohmic metal layer to be made thinner without compromising manufacturing control or introducing unwanted diffusion effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If polysilicon layers are heavily doped to reduce resistance, then the electrical conductivity improves, but the reactivity with other material layers increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidreactivity with other material layers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The structure separates the doping function (first polysilicon layer) from the barrier function (second polysilicon layer). This allows the first layer to be heavily doped for low resistance while the second layer remains relatively pure to provide chemical stability and prevent reactivity with adjacent material layers, thus resolving the contradiction between conductivity and reactivity.

Inventive Principle:

Principle #1Segmentation

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 configuration reduces the resistance and reactivity of the electrode structure, prevents impurity diffusion, and enhances the manufacturing process flexibility by maintaining low resistance and preventing impurities from diffusing to the semiconductor substrate.

Implementation Method 1

a second polysilicon layer for adjusting grains, formed on the first polysilicon layer doped with the resistance adjustment impurities and additionally doped with grain adjustment impurities

Methodology Applied

Scientific EffectGrain boundary strengthening: Grain Boundary Strengthening

Implementation Method 2

a barrier metal layer formed on the ohmic metal layer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Data Source

PatentUS10685959B2Electrode structure, method of fabricating the same, and semiconductor device including the electrode structure

Publication Date: 2020.06.16 SAMSUNG ELECTRONICS CO LTD

AI summary

An electrode structure is disclosed. The electrode structure includes a first polysilicon layer doped with resistance adjustment impurities; a second polysilicon layer for adjusting grains, formed in the first polysilicon layer and doped with grain adjustment impurities; an ohmic metal layer formed on the first and second polysilicon layers; a barrier metal layer formed on the ohmic metal layer; and a metal layer formed on the barrier metal layer.