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{{cc-nanolab}}
[[Category:346]]
 
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Preparation click here]'''
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=The Process Flow=
=The Process Flow=
A Process Flow contains the sequence of steps and techniques used to create certain structures and devices at the microscopic and nanoscopic scales. This involves a combination of various fabrication methods and inspection techniques to achieve the desired features and functionalities.   
A Process Flow contains the sequence of steps and techniques used to create certain structures and devices at the microscopic and nanoscopic scales. This involves a combination of various fabrication methods and inspection techniques to achieve the desired features and functionalities.   


Starting a process flow from scratch with little or no previous knowledge can be challenging. Please do not hesitate to reach out to colleagues, other cleanroom users or our Fabrication Support team at [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk] for help with your process, discussions regarding problems or improvement.   
Starting a process flow from scratch with little or no previous knowledge can be challenging. Please do not hesitate to reach out to colleagues, other cleanroom users or our Fabrication Support team at [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk] for help with your process, discussions regarding problems or improvement.   
Below are some recommendations on how to set up a process flow and more information on the different parts of a process flow, including an overview of various process steps. You can then find more detailed information about equipment, processes and materials available on the specific subpages. We also recommended to have a look at the process log on [https://labmanager.dtu.dk/ www.labmanager.dtu.dk] for the specific machine to check which process parameters or programs other users (f.ex. group members) are using.
You might also have special requirements in your process flow. Please find below a short description of how to get approval for new chemicals or processes.


If you are a new user to DTU Nanolab and you have issues on how to get started in our cleanroom, please have a look at following pages in labadviser: '''[[LabAdviser/Safety|"Safety"]]''' and '''[[Specific Process Knowledge/Getting Started|"Getting Started"]]'''.   
If you are a new user to DTU Nanolab and you have issues on how to get started in our cleanroom, please have a look at following pages in labadviser: '''[[LabAdviser/Safety|"Safety"]]''' and '''[[Specific Process Knowledge/Getting Started|"Getting Started"]]'''.   


Below are some recommendations on how to set up a process flow and more information on the different parts of a process flow, including an overview of process steps. More detailed information can be found on the specific process pages. 


'''General Overview of a Process Flow'''
'''General Overview of a Process Flow'''
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Before implementing new processes, we strongly recommended you to get your process validated by our Fabrication Support team. This is done to ensure safety to all cleanroom users and to guard involved machinery and equipment during the processing, e.g. avoid cross-contamination issues, as well as to support your work in the cleanroom. Process flows or any questions regarding process flow review can be submitted to [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk].
Before implementing new processes, we strongly recommended you to get your process validated by our Fabrication Support team. This is done to ensure safety to all cleanroom users and to guard involved machinery and equipment during the processing, e.g. avoid cross-contamination issues, as well as to support your work in the cleanroom. Process flows or any questions regarding process flow review can be submitted to [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk].
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'''Process Flow Template'''


You can download a process flow template below and fill it in with your own information. Of course, you are also welcome to make your own template. You are also welcome to take a look at our example for the fabrication of a simple solar cell. It shows you how to build up a process flow for a component that can be made at DTU Nanolab. Throughout the example, you can find links to relevant pages in LabAdviser where information about the different processes are given. Please note that there is also a possibility to create a process flow in Labmanger using the [http://labmanager.dtu.dk/function.php?module=Flow&view=editflow Flow editor].<br>
You can download a process flow template below and fill it in with your own information. Of course, you are also welcome to make your own template. You are also welcome to take a look at our example for the fabrication of a simple solar cell. It shows you how to build up a process flow for a component that can be made at DTU Nanolab. Throughout the example, you can find links to relevant pages in LabAdviser where information about the different processes are given. Please note that there is also a possibility to create a process flow in Labmanger using the [http://labmanager.dtu.dk/function.php?module=Flow&view=editflow Flow editor].<br>
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'''Process flow template:''' [[Media:Process flow template v3.1.docx|Process_flow_template_v3.1.docx]]
Process flow template: [[Media:Process flow template v3.1.docx|Process_flow_template_v3.1.docx]]
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'''Process flow example:''' [[LabAdviser/Introduction to LabAdviser and Processing/Solar cell process flow|Solar Cell Process flow]]
Process flow example: [[LabAdviser/Process Flow/Solar cell process flow|Solar Cell Process flow]]


<br>In the following section, you can find some guidelines and relevant information for creating your own process flow, such as relevant information about substrate, pattern design and mask fabrication, as well as process steps and characterization methods.
<br>In the following sections, you can find some guidelines and relevant information for creating your own process flow, such as relevant information about substrate, pattern design and mask fabrication, as well as process steps and characterization methods.
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== Substrate ==
== Substrate ==
Generally, there is a wide range of substrates available for cleanroom processing. This includes silicon, fused silica, III-V substrates, SOI wafers, but also rarer and more expensive materials such as silicon carbide, saphire, and diamond are possible. In some occasions, even different types of polymer can be processed at DTU Nanolab.  
Generally, there is a wide range of substrates available for cleanroom processing. This includes silicon, fused silica, III-V substrates, SOI wafers, but also rarer and more expensive materials such as silicon carbide, saphire, and diamond are possible. In some occasions, even different types of polymer can be processed at DTU Nanolab.  
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| width="150" align="center" style="color:black"| Create a Mask on your Sample [[image:Jehanmask.png|130px|frameless|link=Specific Process Knowledge/Pattern Design|Lithography is a common method to create micro- and nanoscale patterns on a substrate. The process commonly involves (a) coating of the substrate with a UV- or DUV-light, or e-beam sensitive resist; (b) exposure of parts of the pattern; and (c) development.]]
| width="150" align="center" style="color:black"| Create a Mask on your Sample [[image:Jehanmask.png|130px|frameless|link=Specific Process Knowledge/Pattern Design|Lithography is a common method to create micro- and nanoscale patterns on a substrate. The process commonly involves (a) coating of the substrate with a UV- or DUV-light, or e-beam sensitive resist; (b) exposure of parts of the pattern; and (c) development.]]
| width="150" align="center"  style="color:black"| Transfer a Pattern to your Sample [[image:JehanTransfer.png|130px|frameless|link=Specific Process Knowledge/Etch|Etching is used to remove material from the surface of a substrate to create patterns and structures. Often a mask is used to selectively remove material. Etching can be done by using liquid chemicals (wet etching), or gas or plasma (dry etching ).]]
| width="150" align="center"  style="color:black"| Transfer a Pattern to your Sample [[image:JehanTransfer.png|130px|frameless|link=Specific Process Knowledge/Etch|Etching is used to remove material from the surface of a substrate to create patterns and structures. Often a mask is used to selectively remove material. Etching can be done by using liquid chemicals (wet etching), or gas or plasma (dry etching ).]]
| width="150" align="center"  style="color:black"| Define your Structure directly [[image:JehanDefine.png|130px|frameless|link=Specific Process Knowledge/Direct Structure Definition|Structures can be directly created in the device material without an lithography and etch step, though some of the techniques may require a stamp.]]
| width="150" align="center"  style="color:black"| Create your Structures in Polymer [[image:JehanDefine.png|130px|frameless|link=Specific Process Knowledge/Direct Structure Definition|Structures can be directly created in the device material without an lithography and etch step, though some of the techniques may require a stamp.]]
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| width="150" align="center" style="color:black"| Characterize your Sample[[image:JehanCharacterize.png|130px|frameless|link=Specific Process Knowledge/Characterization]]
| width="150" align="center" style="color:black"| Characterize your Sample[[image:JehanCharacterize.png|130px|frameless|link=Specific Process Knowledge/Characterization]]
| width="150" align="center"  style="color:black"| Cut & Pack your Sample (Backend) <br> <br> [[image:JehanPack.png|130px|frameless|link=Specific Process Knowledge/Back-end processing|Back-end processing, also called Assembly and Packaging, are typical processes used to finish up the wafer/chip fabrication, f.ex. wafer thinning, dicing into chips, bonding to a carrier and connecting it with wires to a printed circuit board (PCB).]]
| width="150" align="center"  style="color:black"| Cut & Pack your Sample (Backend) <br> <br> [[image:JehanPack.png|130px|frameless|link=Specific Process Knowledge/Back-end processing|Back-end processing, also called Assembly and Packaging, are typical processes used to finish up the wafer/chip fabrication, f.ex. wafer thinning, dicing into chips, bonding to a carrier and connecting it with wires to a printed circuit board (PCB).]]
| width="150" align="center"  style="color:black"| Process Flow Examples [[image:Processflow b.png|130px|frameless|link=Specific Process Knowledge/Solar cell process flow|We have made the process flow for a simple solar cell available. It shows you how to build up a process flow for a component that can be made at DTU Nanolab.]]
| width="150" align="center"  style="color:black"| Process Flow Examples [[image:Processflow b.png|130px|frameless|link=LabAdviser/Process Flow/Solar cell process flow|We have made the process flow for a simple solar cell available. It shows you how to build up a process flow for a component that can be made at DTU Nanolab.]]
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''take out: characterization and process flow examples, exchange direct structuring with polymer processing''
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* ''Polymer Processing:''  
=== Examples for Information relevant to a Specific Process Step ===
** ''Hot Embossing''
Please find below some examples that might help you to create a complete process step. If you need assistance, do not hesitate to contact our [mailto:training@nanolab.dtu.dk Fabrication Support Team].
** ''Injection Molding''
** ''Imprinting: Imprinting, specifically Nanoimprint Lithography (NIL), is a polymer replication process involving a resilient stamp to transfer nano- or microscale patterns onto a substrates coated with a liquid or soft thermoplastic film.''
'''Create a Mask on your Sample (Photolithography Step)'''
** ''PDMS casting''
* Specify the design/mask-name, -layers, and polarity used for each photolithography step
** ''3D printing''
* Specify if required and type of alignment (frontside, backside), and if relevant note down alignment marks coordinates
** ''2 photon-polymerization (2PP)''
* Specify resist and resist thickness (defines spin process)
* Specify developer
* Specify Spin Coating equipment and process (depending on resist type and thickness)
* Specify Aligner equipment and process including exposure conditions (f.ex. exposure dose)
* Specify Developer equipment and process (depending on resist type and thickness)
* Define tolerance or other inspection criteria
* Check cross-contamination with pre- and post process equipment




'''Deposit a Thin Film on your Sample (Metal Evaporation)'''
*Specify metal thicknesses, and deposition rate
*Specify Evaporator equipment, process name
*Define tolerance or other inspection criteria
*Check cross-contamination with pre- and post process equipment


'''Some examples for information relevant for a specific process step'''
 
*<u>f.ex. Photolithography</u>
'''Transfer a Pattern to your Sample (Dry etching) '''
** Specify the design/mask-name, -layers, and polarity used for each photolithography step
* Specify Etching Tool
** Specify if required and type of alignment (frontside, backside), and if relevant note down alignment marks coordinates
* Specify process name, etch parameters, etch depth
** Specify resist and resist thickness (defines spin process)
* Define tolerance or other inspection criteria
** Specify developer
* Check cross-contamination with pre- and post process equipment
** Specify Spin Coating equipment and process (depending on resist type and thickness)
** Specify Aligner equipment and process including exposure conditions (f.ex. exposure dose)
** Specify Developer equipment and process (depending on resist type and thickness)
** Define tolerance or other inspection criteria
** Check cross-contamination with pre- and post process equipment
*<u>f.ex. Metal Evaporation</u>
**Specify metal thicknesses, and deposition rate
**Specify Evaporator equipment, process name
**Define tolerance or other inspection criteria
**Check cross-contamination with pre- and post process equipment
* <u>f.ex. Dry etching</u>
** Specify Etching Tool
** Specify process name, etch parameters, etch depth
** Define tolerance or other inspection criteria
** Check cross-contamination with pre- and post process equipment
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== Characterization ==
== Characterization ==
<span style="background:#FF2800">THIS PART IS STILL UNDER CONSTRUCTION</span>


A crucial and often neglected part of each process flow is the characterization. After critical process steps you might need to analyze and measure the properties of produced structures, layers, materials or entire devices. Characterization techniques help you ensure that the fabricated components meet the required specifications and function correctly. There are many tools and methods available to inspect, analyze and measure the properties of features and materials such as physical, chemical, electrical, and mechanical properties.  
A crucial and often neglected part of each process flow is the characterization. After critical process steps you might need to analyze and measure the properties of produced structures, layers, materials or entire devices. Characterization techniques help you ensure that the fabricated components meet the required specifications and function correctly. There are many tools and methods available to inspect, analyze and measure the properties of features and materials such as physical, chemical, electrical, and mechanical properties.  


Even if some of these methods are fast and cheap to perform, not all information might be relevant for the fabrication of your device taking up unnecessary resources. It is, therefore, vital to chose methods relevant for you process and product. Please do not hesitate to reach out to our Fabrication Support team at [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk].
Even if some of these methods are fast and cheap to perform, not all information might be relevant for the fabrication of your device taking up unnecessary resources. It is, therefore, vital to chose methods relevant for you process and product. Please do not hesitate to reach out to our Fabrication Support team at [mailto:nanolabsupport@nanolab.dtu.dk nanolabsupport@nanolab.dtu.dk].
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Below we will try to sum up some of the more typical characterization methods, but for now, please have a look at the [[Specific Process Knowledge/Characterization | '''Characterization''']] page.


<span style="background:#FF2800">THIS PART IS UNDER CONSTRUCTION</span>


'''Overview over some Processes available at DTU Nanolab'''
===  Surface Toppography ===
''Analysis of form, shape, size, structure, and surface features including surface roughness, f.ex''
* Light microscopy
* Electron beam microscopy: SEM; TEM
* AFM
* Optical or mechanical profilometer
* Particle Scanner
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=== Chemical Composition and Molecular Interaction ===
''Techniques to identify elemental composition and chemical states, as well as the interaction between molecules, f.ex.''
* EDS/EDX (Energy Dispersive X-ray Spectroscopy)
* XPS (X-ray Photoelectron Spectroscopy)
* XRD (X-ray diffraction)
* Contact Angle Measurement
* SIMS (Secondary Ion Mass Spectrometry) – not available at DTU Nanolab
* Raman Spectroscopy - not available at DTU Nanolab
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=== Optical Properties ===
''Analysis of optical properties such as film thickness, optical constants (refractive index, extinction coefficient), reflectivity, and others, f.ex.''
* Ellipsometry
*Spectrophotometry
*Microspectrophotometer
*PhotoLuminescence Mapper
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=== Mechanical Properties ===
''Techniques to measure hardness, elasticity, and stress, f.ex.''
*Stylus profilometer
*Hardness tester
*AFM
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=== Electrical Properties ===
''Techniques to evaluate conductivity, resistivity, and carrier behavior, f.ex.''
*4-Point Probe, Probe station
*III-V ECV-profiler (Electrochemical Capacitance-Voltage carrier density profiler)
*Lifetime scanner MDPmap
*AFM
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=== Others ===
* Thermal Properties
* Magnetic Properties


'''🔬Structural and Morphological Properties:'''


These methods reveal the shape, size, surface features, and internal structure of materials.


* Microscopy techniques: light microscopy, SEM; TEM, AFM
<!--
* X-ray Techniques: XRD
''Drawings in this section done by Jesper Hanberg @DTU Nanolab''
* Others: FIB, Ellipsometry, etc
{| border="2" cellspacing="0" cellpadding="10" align="left"


|-
| width="150" align="center" style="color:black" | Surface Toppography  [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization|Analysis of form, shape, size, structure, and surface features including surface roughness.]]
| width="150" align="center" style="color:black"| Chemical Composition and Molecular Interaction [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization|Identication of elemental composition and chemical states as well as molecular interactions.]]
| width="150" align="center" style="color:black"| Mechanical Properties [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization|These techniques measure hardness, elasticity, and stress.]]
|-


'''⚛️Chemical Composition:'''
|-
| width="150" align="center" style="color:black"| Optical Properties [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization]]
| width="150" align="center" style="color:black"| Electrical Properties [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization]]
| width="150" align="center" style="color:black"| Thermal Properties [[image:JehanCharacterize.png|130px|frameless|link=Specific_Process_Knowledge/Characterization]]
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|}
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These techniques identify elemental composition and chemical states.
== Special Requirements ==


* Spectroscopy Techniques:
You might have special requirements in your process that require
** EDS/EDX (Energy Dispersive X-ray Spectroscopy) – elemental analysis (often with SEM)
* chemicals not already approved and/or available in the cleanroom
** XPS (X-ray Photoelectron Spectroscopy) – surface chemistry and oxidation states
* processes not available on our machines
** SIMS (Secondary Ion Mass Spectrometry) – depth profiling and trace elements - not available at DTU Nanolab
* parameters outside allowed parameter range
** Raman Spectroscopy – vibrational modes, material identification - not available at DTU Nanolab
* processing materials not allowed or available in an equipment
* others special requirements.


In this section we try to elaborate on a few of these topics. Some might have been mentioned in the [[LabAdviser/Safety#"DTU Nanolab Introductory Course: Cleanroom in B346"|DTU Nanolab Introductory Course: Cleanroom in B346]]. If you still have questions, please contact our [mailto:training@nanolab.dtu.dk Fabrication Support Team].
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=== Approval of Special Materials and Processes (Risk Assessment)===
If you require chemicals, substrates or would like to run a new process that are not already approved and/or available in the cleanroom, you need to fill out a Risk Assessment (in danish: "Risikovudering (RA)). In the RA, the intended work process with involved chemicals (including concentrations), safetry equipment and involved risk assessment must be described. The RA form is available in english and danish on [https://kemibrug.dk/APV '''Kemibrug''']. Please note that historically the risk assessment can be called "work place assessment" (or in danish arbejdspladsvudering (APV)).


'''⚡Electrical Characterization: four-point probe'''
The completed RA form and the safety data sheet (SDS) from the manufacturer or importer must be send to our [mailto:mbec@dtu.dk Safety Coordinator] for evaluation and approval of your process.  
 
Non-Standard chemicals need to be purchased by users themselves. If you need assistance, please contact the [mailto:nanolabsupport@nanolab.dtu.dk Fabrication Support Team].
Used to evaluate conductivity, resistivity, and carrier behavior. 
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'''🔥 Thermal Properties''' 
 
These methods assess how materials respond to heat.
 
'''🧲 Magnetic Properties''' 
 
Important for spintronics and magnetic storage applications.
 
'''🧱 Mechanical Properties''' 
 
These techniques measure hardness, elasticity, and stress. 
 
* Special modes in AFM: Nanoindentation, Force Modulation Mode, ect
* Stylus profilometer (bending, thin film stress) 
 
'''🔬 Optical Properties'''
 
* ellipsometry?
* transmission ...
 
== Special Requirements ==
How to deal with ...


* Buy special chemicals (approval by DTU Nanolabs safety representant required)
===Specialized Processes and Cross Contamination (Equipment)===
* Special materials, resists, developers, solvents, or etchants, please ... discuss with nanolab staff, fill out APV, buy yourself
For each equipment, our specialists have defined a parameter range in which the tool is safe to operate - safe for the tool and operator, and safe for the samples commonly processed. You must contact the responsible equipment group '''beforehand''', if you want to
* Standard chemicals are available in the cleanroom (find a list here)
* run processes with parameters outside the range specified in the manual
* UV or DUV Masks: link
* process materials not allowed in the machine
* cleanroom shelf space
You can find the respective contact details in labmanager on the "Basic Info" page. You are also welcome to contact the [mailto:nanolabsupport@nanolab.dtu.dk Fabrication Support Team] for assistance.
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