PT-MTL - Capabilities, Specifications and Operation
Plasma Therm Metal Etcher Information and Operating Instructions
PT-MTL is an ICP (Inductively Coupled Plasma) etch system configured for metal etching using Cl or F chemistry. It is a single wafer etcher with a load lock. The equipment can be configured to etch either a 4” or a 6” wafer. It has both laser interferometer and optical emission endpoint. A camera is also available for substrate observation.
List to be added here.
Performance of the Tool:
What the Tool CAN do:
- System is mainly used for metal etch applications. It has both fluorine (CF4) and chlorine (Cl and BCl3) source gases.
- Can etch 4” or 6” wafer – make sure the equipment is in the correct configuration for processing. Conversion between substrate sizes take approximately 3 hours.
- Can be used for processing pieces – make sure the pieces are attached to a carrier wafer; ensure that pieces do not extend into the clamp region (5 mm from edge of the wafer).
What the Tool CANNOT do:
- Wafers with resist or particles on the back of the wafer are not allowed as it will cause wafer breakage/ backside He errors.
- Wafers with no EBR are not allowed in the etcher. 2mm EBR for thin resist (<2um) and 5mm EBR for thicker resist is required to prevent wafers from dropping in the chamber.
- Transparent wafers are currently an issue for processing. Here is a procedure on How to Process Transparent Wafers.
The following people make up the Tool Quality Circle:
- Process Staff: Nancy Latta, Jim McVittie, Usha Raghuram
- Maintenance: Elmer Enriquez
- Super-Users: Jim Kruger
Consult the training calendar for a training session that is convenient to attend.
Contact the appropriate staff member or super user.
Read the training materials.
**Shadowing a qualified user prior to the training session is highly recommended and will speed up your understanding of the tool.
· Process pressure, Max = 100 mTorr
· Backside He Pressure, Max = 10 Torr
· Bias Power, Max = 600 Watt
· ICP Power, Max = 1200 Watt, min 200W
· Electrode Temp, Max = 60°C, Min = 10°C
· Lid Temp, Max = 180°C
· Liner Temp., Max = 180°C
· Spool Temp., Max = 180°C
· Cl2, Max Flow = 114.2 sccm
· BCl3, Max Flow = 119.55 sccm
· O2, Max Flow = 96.6 sccm
· SF6, Max Flow = 103.6 sccm
· Ar, Max Flow = 98.1 sccm
· CF4, Max Flow = 101.8 sccm
· CH4, Max Flow = 135.7 sccm
· N2 , Max Flow = 194.0 sccm
More parameter information for the PT-MLT system can be found here. This is a link to the default Process Step page in WIKI.
- Load Lock.
- Reaction Chamber.
- Process Monitor/Control Computer.
- Mechanical Pumps – located in basement.
- Heat exchanger – located next to the tool.
- Specifics to PlasmaTherm are in this section.
- PT-MTL can be used to process either 4” or 6” wafers.
- Both the bottom electrode chuck and the transfer arm have to be set to the correct wafer size configuration.
- Verify the tool configuration and status in Badger before running your process.
- Follow the link for general operating procedure for all PlasmaTherm etchers: Plasma Therm Etchers - General Operating Procedure
- Note that Recipe Sequence is a combination of several Recipe Steps and that in the Plasma Therm Versaline systems the Sequence as well as recipes Steps are stored separately. If a recipe step is modified and saved, the changes are effective in all the sequences the recipe step is used even if the sequence is not edited.
- Always make sure that the recipe parameters are correct before running any process.
Recipe Sequence Example: Al Etch Recipe
|Process Parameter||Units||Stab||Light1||Light2||Main Etch||Post Etch
|He backside P||Torr||4||4||4||4||4|
<to be written>
Special Considerations for use of the Tool
Transparent Wafers (quartz, pyrex, sapphire or glass) present unique loading issues. A procedure for the loading of these substrates can be found here.
Process Monitoring and Machine Qualification
Quals are run after major repairs to the system, when a labmember reports a variance from normal results and on a routine basis.
Procedure <work in progress>
Description of test wafers- Al on ox, patterned ox, patterned bare Si.
Description of recipe using timed etch and using endpoint etch.
Description of measurement procedures- nanospec, woollam, alpha step, prometrix
Description of recording of results- badger, wiki, MES Enterprise
Quals may be run by concerned labmembers before running critical processes or as a measure of tool functionality. Staff members will run quals routinely or as needed or requested.
Recommendation to users with critical processes
It would be wise to run the qual before committing valuable samples to the deposition.
Red: Tool is in shutdown due to serious hardware or software issues. Maintenance staff has been notified.
Yellow: Tool has an issue that will allow for the running of some but not all recipes. For example, a gas not common to all recipes is under repair/observation.
Green: All recipes and processes may be run.
Process Monitoring Results: recent qual results will be posted on the lab management system (badger) and on the Recent Qual Results page
1000W ICP/ 150W BP/ 70 Cl2/ 20 BCl3/ 10N2/ 7mT/4T BSHe/ Electrode 20C/Lid 90C/Liner 70C
To view the full process sequence of the qual recipe click here.
Etch rate Data (3/9/2013)
Please note; Etch rate and selectivity data is based on etching six inch wafers. Four inch results should be slightly different.
· Al Etch Rate = 6208A/min; Uniformity = 10.7%
· (based on 9 pt Rs measurements; 10mm edge excl; Al Resistivity = 2.86E-02 ohm-cm)
· Oxide ER = 964A/min; Uniformity = 6.85% (NanoSpec; Thermal oxide; 9 pt)
· Photo resist ER = 4727A/min; Unif = 11.9% (SPR3612; 9 pt; NanoSpec)
· Al:PR Selectivity = 1.31