Dry etch is one of the key pattern-transfer processes in semiconductor manufacturing. It is used to create vias, trenches, contact holes, and other micro- and nanoscale structures in dielectric, metal, or semiconductor layers. Unlike wet etching, dry etching uses plasma chemistry and ion bombardment, which allows better control of feature shape, directionality, and critical dimensions.In a typical silicon oxide dry etch process, the wafer is coated with a sacrificial light-absorbing material and photoresist, which define the pattern. The wafer is placed in a plasma etch chamber. Fluorine-containing plasma species interact with exposed SiO₂ and convert it into volatile products, mainly SiF₄, which are removed by the vacuum system. At the same time, ion bombardment assists the reaction, removes passivation or polymer from the feature bottom, and helps form vertical vias or trenches.Two coupled mechanisms control the process:Chemical etching — reactive radicals convert SiO₂ into volatile reaction products. Mechanical / ion-assisted etching — accelerated ions activate the surface, improve directionality, and remove material or polymer from the feature bottom.The main challenge is that the same mechanisms that enable etching can also create defects. Plasma exposure can heat and erode the resist and sacrificial layers, generating water-containing and carbon-containing by-products. SiF₄ may react with moisture and form silicon-oxide or silicon-oxyfluoride particles. Excessive ion bombardment can sputter fragments from the wafer, mask, chamber parts, or focus ring, leading to redeposition, micromasking, residues, blocked vias, or underetched features.Therefore, the goal of this project is to build a functional model of the dry etch system, identify useful and harmful interactions, and understand how process parameters such as plasma source power, bias power, gas chemistry, pressure, temperature, pumping efficiency, and overetch time affect defect formation. The model will help reveal process contradictions and generate practical guidance to reduce particles and residues while maintaining etch rate, profile control, and process stability.

<h2>Improve monitoring and feedback</h2><ol><li data-list="bullet">Track particle count versus source power and bias power.</li><li data-list="bullet">Monitor chamber moisture level.</li><li data-list="bullet">Monitor endpoint and overetch time.</li><li data-list="bullet">Compare defects before and after purge or pulsed steps.</li><li data-list="bullet">Use wafer maps to identify whether particles are center, edge, pattern, or chamber related.</li><li data-list="bullet">Track chamber age, clean count, focus-ring age, and ESC condition.</li></ol>Purpose: move from fixed recipe control to mechanism-based defect control.

<h2>Manage polymer formation</h2><ol><li data-list="bullet">Optimize fluorocarbon gas ratio.</li><li data-list="bullet">Avoid excessive polymer deposition.</li><li data-list="bullet">Use controlled O₂ addition if compatible with profile and selectivity.</li><li data-list="bullet">Keep polymer on sidewalls, but prevent polymer accumulation on the wafer top, chamber parts, and via bottom.</li><li data-list="bullet">Add a gentle polymer-removal step before overetch.</li></ol>Purpose: polymer should protect the sidewall, not become a particle source.

<h2>Reduce sputtering sources</h2><ol><li data-list="bullet">Lower bias power where possible.</li><li data-list="bullet">Reduce Ar or other heavy-ion contribution if sputtering is excessive.</li><li data-list="bullet">Use softer overetch conditions.</li><li data-list="bullet">Optimize focus-ring material and condition.</li><li data-list="bullet">Check chamber coating erosion.</li><li data-list="bullet">Reduce mask, resist, and SLAM erosion.</li><li data-list="bullet">Improve chamber seasoning stability.</li><li data-list="bullet">Replace worn chamber parts before they become particle sources.</li></ol>Purpose: prevent physical fragments from becoming micromasks or redeposited particles.

<h2>Split the recipe into functional steps</h2>Instead of one aggressive etch recipe, use a multi-step recipe:<ol><li data-list="ordered">Pre-dry / stabilization step</li><li data-list="ordered"> remove moisture and stabilize chamber conditions.</li><li data-list="ordered">Main chemical etch step</li><li data-list="ordered"> sufficient source power, moderate bias.</li><li data-list="ordered">By-product evacuation step</li><li data-list="ordered"> purge or low-power plasma to remove SiF₄ and fragments.</li><li data-list="ordered">Controlled bottom-clean step</li><li data-list="ordered"> short bias-assisted step to clear the via/trench bottom.</li><li data-list="ordered">Gentle overetch step</li><li data-list="ordered"> lower bias and lower sputtering risk.</li></ol>Purpose: each step performs one main function instead of creating competing effects.

<h2>Use pulsed plasma or pulsed bias</h2><ol><li data-list="bullet">Pulse the source generator to reduce continuous by-product generation.</li><li data-list="bullet">Pulse the bias generator to reduce continuous ion damage.</li><li data-list="bullet">Use high-bias short pulses only when bottom clearing is needed.</li><li data-list="bullet">Add low-power intervals to allow product evacuation.</li><li data-list="bullet">Test duty cycle, pulse frequency, and pulse timing.</li></ol>Purpose: separate “etching” and “evacuation” in time, instead of forcing the system to do everything continuously.

<h2>Balance source power and bias power</h2><ol><li data-list="bullet">Use source power mainly to control chemical etch rate.</li><li data-list="bullet">Use bias power only as much as needed for anisotropy and bottom clearing.</li><li data-list="bullet">Avoid the combination of very high source power and very high bias power.</li><li data-list="bullet">Reduce bias during overetch.</li><li data-list="bullet">Increase chemical etch contribution while reducing excessive sputtering.</li><li data-list="bullet">Build a process window based on particle count versus source/bias settings.</li></ol>Purpose: keep chemical removal efficient while preventing sputter-generated defects.

<h2>Improve removal of volatile by-products</h2><ol><li data-list="bullet">Increase pumping efficiency during main etch.</li><li data-list="bullet">Optimize chamber pressure to reduce residence time of SiF₄.</li><li data-list="bullet">Increase gas flow or improve gas-flow uniformity.</li><li data-list="bullet">Add purge steps between etch stages.</li><li data-list="bullet">Avoid dead zones where SiF₄ and moisture can accumulate.</li><li data-list="bullet">Improve exhaust conductance.</li><li data-list="bullet">Reduce unnecessary overetch time.</li></ol>Purpose: remove SiF₄ and other reaction products before they react, condense, or redeposit.

<h2>Reduce moisture to prevent SiF₄ hydrolysis</h2><ol><li data-list="bullet">Improve wafer dehydration bake before etch.</li><li data-list="bullet">Optimize resist and SLAM bake to remove absorbed water.</li><li data-list="bullet">Minimize wafer queue time after wet processing or coating.</li><li data-list="bullet">Keep wafers in dry N₂ environment before etch.</li><li data-list="bullet">Improve chamber pump-down and pre-etch purge.</li><li data-list="bullet">Check gas-line moisture contamination.</li><li data-list="bullet">Improve chamber wall temperature control to avoid condensation.</li><li data-list="bullet">Add a short pre-clean / pre-dry plasma step before the main etch.</li></ol><h2>Purpose: reduce H₂O availability so SiF₄ cannot convert back into SiO₂-containing </h2>

This project investigates particle-defect formation during SiO₂ dry etch. Functional modeling revealed that defects can be generated by two coupled mechanisms: chemical formation of SiO₂/SiOFₓ particles from SiF₄ interaction with moisture, and mechanical generation of particles by excessive ion bombardment and sputtering. The proposed improvement direction is to balance chemical etching and ion-assisted etching by properly adjusting the source and bias generators, reducing moisture, improving by-product evacuation, minimizing sputtering, and using pulsed or multi-step process recipes. The goal is to reduce particles and micromasking while maintaining etch rate, profile control, and process stability.

Functional Modeling of Dry Etch at Semiconductor Manufacturing

Projects related to innovations and problem solving in the microchip manufacturing

Functional Modeling of Dry Etch Process at Semiconductor Manufacturing

To increase the removal rate, elevate the concentration of H2O2, but also enhance the polish rate - increase the rotation rate and abrasive particles concentration.

Increase the concentration of the abrasive particles - so, the elevation of the concentration of H2O2 should be accompanied by an increase in the concentration of the abrasive particles

Increase the rotation of the pad - increase the polish rate

This project investigates how to increase the copper removal rate during Chemical Mechanical Planarization (CMP). Functional modeling revealed that increasing H₂O₂ alone is ineffective beyond an optimum level because rapid oxidation creates a thick, passivating Cu₂O/CuO layer that must be mechanically removed. The winning direction is to balance faster oxidation with stronger mechanical removal by optimizing pad speed, abrasive concentration, pressure, conditioning, and slurry transport.

Increase the removal rate of Cu at CMP

The extent to which a user is able to learn how to operate, operate or control a system or object.  The convenience of use.

Ease of operation

Dynamism

Mechanics substitution

Pneumatics or hydraulics

Discarding and recovering

Component: H2O2 solution

The internal or external contour or profile of a component or system as required for ergonomic and function rather than aesthetic reasons

Shape

To simplify the polish (CMP) operation, it is proposed that the bulk of the Cu be removed at the electroplater just after the completion of the electrodeposition. It is a straightforward process to replace the polarity to make the wafer an anode and give (-) to the anode. It will dissolve the main affected part of the Cu and simplify the following operation - polish.

"Composite materials" is a good principle; maybe we can dip the wafer into another liquid with very low surface tension that is soluble in the electrolyte, such as ethanol or IPA.

"Partial or excessive action" - to make a prewet of the wafer before the inserting into the electrolyte

Another direction for development and real innovation is to remove the residue at the previous operation - dry etch. In this case the Wet etch operation will not be necessary and can be eliminated.

Instead of pouring the solution on the rotating wafer, we can do the opposite and place it face down in the solution bath.

To make Dry etch process in pulses to ensure the pump to pump out and to remove SiF4 and all other gaseous by-products

Etch stop is needed only on the surface of Cu to prevent Cu diffusion from the bottom Cu metal line to the top ILD. Instead of depositing the Etch Stop material with CVD; it is proposed to elaborate a process of selective deposition of PMMA with dissolved SiC or SiN. The liquid can be spined on the wafer and removed from the ILD (SiO2) areas.

To ensure a small gap between the metal line and ILD. It could be made in different ways, such as using soluble Barriers, we can use a difference in temperature expansion coefficients, etc.

Use ILD with non-uniform density. Actually, we need high density of the material to prevent diffusion of Cu in to ILD

Use silicide passivation instead of a thick Ta barrier layer.

The cleaning solution dissolves the residue, but the contaminated solution remains on the wafer and should be removed by the wafer rotation. The rotation of the wafer results in the removal of the cleaning solution. I would propose to apply "Other way around" principle. Instead of pour out the solution on the rotating wafer, we could rotate the wafer (face down) in the bath of the solution. It gives a better possibility of managing the temperature and renovating the cleaning solution on the wafer surface.

Another idea regarding Step 4 - Via Patterning simplification:Why do we need to develop exposed PR at all? Exposed PR is removed by an aqueous solution, meaning it can be removed by plasma. So, the idea is to apply plasma etch directly after exposure.

Regarding the Step 4 - Photo Lithography (PL) operation simplification: Why do we develop within the costly PL equipment? Developing the exposed resist is just a wet etch/clean process that can be performed with regular cheap wet cleaning equipment.

In Step 3 - Sacrificial Light Absorbing Layer deposition - use hot air for the material solidification on the wafer during the Spinon process. This will allow the termination of the furnace and additional movements of the wafer. The high pressure above the rotating wafer will prevent the material from contamination.

Air daps also prevent the formation of voids within the metal via a metal line - we already have voids. Very strong Cu-electromigration might slightly affect the surface of the via and metal line, but the voids will not be formed within the metal.

Semiconductor devices are becoming more complex and expensive. But what exactly are we paying for when we buy a computer, cellphone, or any device containing a microchip? It’s not for radically new functions—the core components remain the same: transistors and interconnections. According to Moore’s law, transistors are getting smaller, with more interconnection layers added, making the manufacturing process longer and more costly.

In reality, we’re paying for the inability of engineers to efficiently solve engineering challenges.

This project leverages System Functional Modeling (SFM) to analyze the IC interconnection layer and Process Functional Modeling (PFM) to evaluate its manufacturing process. These analyses aim to deepen our understanding of both the device and the production process, generating innovative solutions for cost reduction and improved efficiency.

Optimizing IC Interconnection: A Functional Approach to Innovation (Stay updated on the project's progress)

Optimizing IC Interconnection: A Functional Approach to Innovation

No diffusion of Cu or voids formation due to electromigration effect - Metal line remains unchanged

Local quality

Merging

Parameter changes

Version: Basic version, Component: Barrier - top layer

Loss or waste of elements of a system or its surroundings – substances, materials, sub-systems, products, fields, etc.  Can be partial or complete, permanent or temporary.

Loss of substance

The barrier takes the volume of the via and trench therefore, the volume of the metal via and metal line becomes smaller, reducing the conductivity of the line and affecting the current as a product

The nozzle directs the solution to the wafer to dissolve the residue

Segmentation

Component: Nozzle

This parameter is designed as a catch-all for any form of inefficiency internal to or around a system that manifests as a harmful effect on something around the system.  Can also mean any form of pollutant or environmental emission generated by a system or object.  This is a derivative of the 'loss of substance' definition above, the focus however is on "harmful emissions" this aspect is on the production of chemicals, etc. that was not one of the original substances contained within the system.

Object generated harmful factors

The cleaning solution, together with the dissolved residue remains on the wafer and should be removed by the wafer rotation

The Other way around

Intermediary

Component: Pump

The measure of an object's capacity for doing work.  This parameter focuses on the actual amount of energy (rather than the efficiency of its use, see 27).  'Moving' includes any situation where there is any degree of relative motion between two or more parts related to the problem.  The relative motion may be a few microns or larger amounts.

Use of energy by moving object

Gaseous by-products are not removed and the etch rate reduces

Issues related to manufacturing, fabrication, and assembly and issues associated with an object or system.  Ease of manufacture.

Ease of manufacture

Creation of Cu(2+) ions that are needed for the electrolysis

Partial or excessive action

Composite materials

Component: Electrolyte

Any dimension relating to surfaces or surface area. These may be internal or external. They may also include contact area as well as actual surface area. 'Stationary' includes any situations where there is no form of relative motion between two or more parts related to the problem.

Area of stationary object

The electrolyte does not perfectly remove all the air from the wafer surface and structure

Functional Modeling of the traditional layer

Step 1 Etch Stop Deposition

Step 2 ILD Deposition

Step 3 Sacrificial Layer Deposition for Via

Step 4 Photolithography patterning for Via

Step 5 Via Etch

Step 6 Wet Cleaning after Via Etch

Step 11 Ta-Barrier + Cu-Seed layers Deposition

Step 12 Cu Electroplating

Step 13 Excessive Cu and Barrier Removal by Polish

Step 4 M - Critical Dimensions Measurements (CDM) - Via

Step 7 Sacrificial Layer Deposition for Trench

Step 8 Photolithography Patterning for Trench

Step 8 M - Critical Dimensions Measurements (CDM) - Trench

Step 9 Trench Etch for Metal Line

Step 10 Wet Cleaning after Trench Etch

Step 11 M - Defects Detection & Measurements

Process Functional Modeling - Typical Process

(In development) Process Functional Modeling - New Process

To redesign the pins from straight and vertical, they could be spherical or tilted

Some parts of the pedestal can be made flexible

Perform the process in vacuum to avoid atmosphere flow

Maybe keep the wafer with a vacuum to avoid any movement of the wafer

Wafer moves within the chamber during the flash heating

Flash heating of a wafer is widely used in microchip manufacturing. The purpose of the process is to prevent the diffusion of ions and atoms. During the flash process, a wafer breakage occurs. The project's purpose is to learn and understand the mechanism of the wafer breakage and propose the solutions to prevent the wafer breakage

Wafer breakage at flash heating

Preliminary action

Spheroidality - Curvature

Flexible shells and thin films

The extent to which an object is able to resist changing in response to force.  Resistance to breaking.  Can mean elastic limit, plastic limit, or ultimate strength; tensile or compressive; linear or rotational.  Also includes toughness and hardness.

Strength

Component: Centering pins

The pedestal has a special configuration: the wafer moves and can get a mechanical hit

Wafer moves due to air pressure difference appearing due to flash heating

Fixate the wafer - no movements at all (vacuum chuck?)

Run additional wafers to compensate for the broken wafers

Redesign the pedestal or add a ring having no "walls" - no parts that the wafer can hit

Redesign the pedestal to exclude a mechanical hit

Flash heating is needed for implant ions activation

Different temperatures cause different pressures of nitrogen

Rapid thermal expansion of chamber gases inducing convective currents

The wafer should move during the flash heating process

Mechanical hit of the wafer with centring pins

Wafer got a mechanical hit during the flash heating process

Redesign centering pins with flexible, low-friction polymer coatings or spring-loaded tips that absorb minor impacts and allow self-centering without causing damage during wafer movement.

Redesign the quartz pedestal with additional low-profile support ridges or pins positioned to provide lateral stability to the wafer, preventing displacement from gas flows while maintaining uniform light exposure.

Process in a vacuum or at least in low pressure

Add the same flight on the bottom to get the same temperature

Integrate in-situ plasma-assisted activation during implantation to partially activate ions, reducing the reliance on subsequent high-temperature flash heating steps.

Use a belt with deposited piezoelectric material. Collect the dust on the belt and remove the dust from the belt due to the belt rotation

Use the piezoelectric plate as a collector of the dust due to electrostatic effect

To use the electrostatic effect to collect the dust

Use piezoelectric plate to generate electricity due to bending

Use the other way around - opposite - generate electricity when moving

Replace the battery for another device that generate energy when it is needed

Eliminate a battery - replace it for another source of energy

This project showcases how functional modeling can drive innovation by analyzing and simulating various versions of a vacuum cleaner. By studying the functional model, you will experience firsthand how the Functional Modeling creative thinking tool helps identify opportunities for improvement and generate innovative ideas for the next generation of products.

Through this example, you’ll learn how to dissect the functionality of a vacuum cleaner, revealing ways to enhance its performance, efficiency, and user experience—ultimately paving the way for future innovations.

Functional Modeling of a Vacuum Cleaner: A Pathway to Innovation

Projects dedicated to mechanical engineering

Vacuum cleaner Functional modeling

Anything related to the cubic measure of space occupied by an object or the space around it.   'Moving' includes any situations where there is any degree of relative motion or mobility between two or more parts related to the problem.  This relative motion may be a few microns or a considerable distance.

Volume of moving object

Taking Out (Extraction)

Universality

The number of useful (value-adding) functions or operations performed by a system per unit time.  The time per unit function or operation.  Useful output per unit of time.  Cost per unit output, or amount of useful output.  (See 'Speed' –  #14 – which is more focused on issues of dynamics rather than the output of product.)

Productivity

The battery charges and supplies electricity for the DC motor

Periodic action

Loss or waste of energy that does not contribute to any of the useful functions being performed.  Inefficiency.  Can be partial or complete, permanent or temporary.

Loss of energy

Any interaction that is intended to change an object's condition.  Can be linear or rotational; the term applies equally well to torque.

Force

Mechanical vibration

Copying

System' Complexity – The number and diversity of elements and element interrelationships within and across the boundaries of a system.  The user may be an element of the system that increases the complexity.  Includes issues like the number of functions, number of interfaces and connections, excessive number of components.    'Control' Complexity – complexity of the control system – either physical components or the algorithms that it contains- used to control a system in delivering useful functions.

Device complexity

Battery consumes energy even without usage

Equipotentiality

The measure of an object's capacity for doing work.  This parameter focuses on the actual amount of energy (rather than the efficiency of its use, see 27).  'Stationary' includes any situation where there is no form of relative motion between two or more parts related to the problem.

Use of energy by stationary object

Porous materials

The amount, quantity, or a number of a system's materials, substances, parts, fields or sub-systems.  'Substance' is used in its most generic form in the TRIZ context to include any physical or temporal 'thing'.

Quantity of substance/the matter

Any linear or angular dimension relating to a stationary object.   'Stationary' includes any situations where there is no form of relative motion between two or more parts related to the problem.

Length of stationary object

Version: Basic version, Component: Wire

DC electricity to make the vacuum cleaner operate

Version: Wireless version, Component: Battery

Battery consumes energy even if no operation

Version: Innovative version, Component: Piezoelectric Plate

Version: Wireless version, Component: Filter

Stops dust and cleans the air coming from aerosols

Version: Basic version, Component: Filter

The velocity or speed of an object or the rate of any kind of process or action.  The speed may be relative or absolute, linear or rotational.