Four-Grid Ion Beam Etching for Uniform Tilted-Wafer Etching

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Solution Overview

Problem

Ion beam etching (IBE) systems face challenges with asymmetry etching due to varying incidence distances of ion beams on a tilted wafer, leading to non-uniform etching rates across different locations.

Innovation Solution

The introduction of a four-grid system with a screen, extraction, accelerator, and decelerator grid, along with a deflector system, allows for independent control of ion current density and energy, and additional control over ion beam direction, ensuring uniform etching across a tilted wafer surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If ion beam energy and current density are controlled together, then etching rate is improved, but control precision over etching uniformity deteriorates

Engineering Contradiction:

Improveetching rateVSAvoidetching uniformity control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the ion beam control into four independent grids (screen, extraction, accelerator, decelerator), each controlling a specific aspect of ion beam parameters. This segmentation allows independent adjustment of ion energy and ion current density, enabling precise control of both etching rate and uniformity without the trade-off that would exist in a two-grid system

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

The solution effectively reduces asymmetry etching by ensuring consistent etching rates across different locations on the wafer, enhancing precision and uniformity in semiconductor manufacturing.

Implementation Method 1

The screen grid receives a screen grid voltage to extract ions from the plasma within the plasma chamber to form an ion beam through the hole

Methodology Applied

Scientific EffectElectrostatic extraction: Electrostatics

Implementation Method 2

An ion beam energy for the ion beam through the hole depends on a voltage difference between the extraction grid voltage and the accelerator grid voltage

Methodology Applied

Scientific EffectElectrostatic acceleration: Electrostatics

Implementation Method 3

A trajectory of an ion beam through the hole formed by the screen grid element, the extraction grid element, the accelerator grid element, and the decelerator grid element depends on a voltage difference between a first deflector voltage and a second deflector voltage

Methodology Applied

Scientific EffectElectrostatic deflection: Electrostatics

Implementation Method 4

perform directional etching of the wafer by the ion beam through the hole reaching the wafer

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS12542254B2Grid structures of ion beam etching (IBE) systems

Publication Date: 2026.02.03 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure relates to an ion beam etching (IBE) system including a plasma chamber configured to provide plasma, a screen grid, an extraction grid, an accelerator grid, and a decelerator grid. The screen grid receives a screen grid voltage to extract ions from the plasma within the plasma chamber to form an ion beam through a hole. The extraction grid receives an extraction grid voltage, where a voltage difference between the screen grid voltage and the extraction grid voltage determines an ion current density of the ion beam. The accelerator grid receives an accelerator grid voltage. A voltage difference between the extraction grid voltage and the accelerator grid voltage determines an ion beam energy for the ion beam. The IBE system can further includes a deflector system having a first deflector plate and a second deflector plate around a hole to control the direction of the ion beam.