General lithography
General lithography (%@@@@@%) is all of the support equipment that is required to achieve good lithography.
| General lithography | |
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| Technology Details | |
| Other Names | %@@@@@%, %other names and abbreviations, separated by commas% |
| Technology | %Parent technology% |
| Equipment | List of %@@@@@% equipment |
| Materials | %Optional materials processed% |
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See Reactive ion etching and Plasma etching for an example.
Contents
Method of operation
Describe how the technology works.
Applications
How is this technology used in nanofabrication and what types of devices/research areas is it useful in?
Parameters
Here we describe what parameters are of importance in this technology (e.g. power, temperature...). May not be relevant to some technologies.
Parameter 1
You may want to make a separate sub-page or article specifically for a parameter if this is longer than, say a paragraph or two. If not, get rid of the {{main|xyz}} below the heading.
Subtechnology 1
Describe any sub-technologies of this technology.
Materials
Optional description of materials that can be processed by technology. I think the best example of where this comes in handy would be with LPCVD describing the difference between HTO and LTO.
Equipment
Automated batch equipment
Sample preparation
Sample cleaning
For good photoresist adhesion, wafers should be clean and dry. While a simple process such as rinsing with Acetone and IPA and blowing dry with an N2 gun may suffice for clean wafers, typically a more aggressive clean should be used particularly after multiple processing steps. Suggested processes and equipment is listed below.
Processes
Piranha etch and Nanostrip are good organic cleans for removing residue on the surface of a wafer prior to processing. An oxygen plasma is another good alternative.
Equipment
- YES-CV200RFS(E) - oxygen plasma cleaning system
- CL200 Megasonic Cleaner - aggressive wet cleaning system
Dehydration bake
Because photoresist is hydrophobic, a dehydration bake is necessary to remove all moisture from the surface of the wafer. This can be done simply by placing the wafer on a hotplate but may also be included as part of the vapor prime step, discussed in the next section.
Adhesion promoter
To promote adhesion, HMDS is often applied to a sample prior to applying the photoresist. The recommended method of application is with a vapor prime process in one of the tools listed below. It can also be applied in liquid form and spun on the surface, similar to spinning photoresist, but this has been shown to be less effective.
Equipment
- YES-310TA - Dedicated vapor prime and image reversal oven
- ACS 200 cluster tool - automated spinner and developer for 4" and 6" wafers
Photoresist spinning
The most common method of applying photoresist to a sample is by spinning it on as a liquid and then baking the sample to remove the solvent. There are a variety of tools that can be used to apply the photoresist depending on the size of your sample and type of photoresist used.
Equipment
- Automated batch processing tools
- ACS 200 cluster tool - 4" and 6" only
- Manual spinners
- pieces up to 6" wafers and up to 7" masks
- CEE 200X photoresist spinner 1 - automatic dispense of SPR 220 (3.0) and (7.0)
- CEE 200X photoresist spinner 2 - automatic dispense of SPR 220 (3.0), 1813, and 1827
- CEE 100CB photoresist spinner - fully manual spinner for photoresist and other polymers
Soft Bake
Most photoresists require a softbake to bake off the remaining solvents. For many processes on the ACS 200 cluster tool, this bake is included automatically after the spin step. For manual spinning, this should be performed on a hotplate at the temperature recommended by the photoresist datasheet.
Exposure
The LNF offers several types of exposure, explained in more detail on the Lithography page.
Post exposure bake
Some photoresists recommend or require a post exposure bake. Like the soft bake, this can be performed on a hotplate or in the ACS 200 cluster tool. Please check the photoresist datasheet to determine if this is recommended.
Development
After exposure, the sample should be developed to remove the desired pattern. For most standard resists, this is performed by soaking the sample in a basic solution, although some use solvent based developers. Check the photoresist datasheet to determine the recommended developer.
Equipment
- Automated batch processing tools
- ACS 200 cluster tool - 4" and 6" only, MF 300 and MF 319
- Manual developers
- pieces up to 6" wafers and up to 7" masks
- CEE Developer 1 - AZ 726
- CEE Developer 2 - AZ 726 and Microposit developer concentrate
- Beaker developing
- Base Bench 63 - useful for developing thick photoresist like KMPR
Hard Bake
Some photoresists recommend a hard bake, performed after the development of the sample. This is often recommended prior to performing wet etching processes. Please check the photoresist datasheet to determine if a hard bake should be used.
Plasma Descum
Prior to subsequent processes, a plasma descum is highly recommended. This will remove any residue left after development that may degrade the performance of an etch or the adhesion of a deposition (e.g. when performing a lift-off. Specifically for wet etching, it will also make the photoresist surface hydrophilic, which will ensure even etching by the chemical.
Equipment
For descum, typically, an oxygen plasma step is performed using the YES-CV200RFS(E). Some RIE equipment also can perform the descum step, often immediately before beginning the etch process.
See also
Other related wiki pages
References
Further reading
- LNF Tech Talk for General Lithography is Coming Soon!
- Other stuff, e.g. technology workshop slides
- External links (can be in another section below, if appropriate)
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