IEN - Micro/Nano Fabrication Facility
A. System Contamination Control Policy


IEN manages contamination concerns by (1) evaluating the materials being deposited; (2) substrate materials; and (3) chemicals that could react with these materials.  The overall concept is to provide a standard process and material library while providing flexibility to integrate new materials onto the system. The primary criteria used will be process repeatability for this process library.

Process Separation

Our plan calls for different canisters (e.g. reactors) to process approved substrates and deposition materials. The proposals call for additional reactor canisters to be acquired to minimize the risk of cross-contamination. 

Each canister can only run 1 type of powder sample (same material, structure, but different size, etc.). Users need to provide canisters for their materials.

Old canisters could be cleaned and repurposed as necessary, subject to established cleaning protocols.

The staff will establish a process baseline recipe library that will characterize the material composition and specific characteristics to ensure that the proper materials are being deposited.

New Process Evaluation and User Qualification

The IEN standard operating procedures will include an evaluation of each research user’s process flow.   IEN staff will work with PIs on evaluating the potential new processes users have submitted. Users need to provide detailed descriptions of the sample's materials, how it was prepared, the planned process on the tool, and how much work is required.

That review will determine their required materials.  If the process and substrate combination is both feasible and compatible with existing reactor canisters, the appropriate one will be determined. Once their process is approved, the user will have to pass a qualification test to determine their understanding of the load/unload procedures.  They must independently show system operation and clearly demonstrate and follow all safety precautions when operating the system.

Canister & Precursor Rotation

The SUMS scheduling system will show the usage history for each canister and what processes have been run with the canister, including cleaning.  All canisters will be tracked.

The SUMS system will implement canister reservation rules; users need to request installation of a specific canister 1 week prior to their scheduled process runs and notify all the tool users about the plan.  Cleanroom staff will inspect the canister and install it on the tool a day before the scheduled date. Users will be strongly encouraged to closely schedule all their depositions in a short time period to maximize tool utilization and reduce installation work to switch canisters.

As more chemistries are introduced to the system, we will set up a schedule rotation for the canisters. We will rely on the SUMS (Shared User Management System) system for canister scheduling. Utilizing SUMS, system users could request a specific canister to be installed on the tool for a set period, from 1 run to a series of runs on the system. A corresponding calendar will be published on SUMS and to show what materials can be on the tool. A new calendar will be posted at the beginning of each week for the following week, so that users can plan accordingly.

When scheduling the tool, the user must select their desired material from a drop-down material list. This list of materials will match the planned list of materials available during the requested time slot. If a user wants to run a material that is not listed as available, they will be directed to the new material request form and not allowed to schedule the tool.

The SUMS system will also show precursor rotations: if more precursors are needed in the future for different processes, a schedule of precursors rotation will be established and then posted so that users can reliably plan their experiment workflows.  The most frequently used precursors will remain on the tool, and less frequently used precursors will rotate as requested. The schedule can be adjusted accordingly.

Equipment Clean & Contamination Monitoring

We will closely follow all OEM-recommended maintenance cleaning schedules to ensure the system is maintained to factory specifications.

All canisters will be cleaned on a regular basis.  IEN will either find vendors that can provide cleaning services or develop appropriate procedures with vendors for specific materials.

The cleanroom staff will run a routine bi-weekly test on each specific canister, deposit Al2O3 (or HfO2), then measure the film quality (thickness, uniformity, composition, refractive index, particle level, etc.) to ensure process repeatability and consistency.

Contact Information
The Institute for Electronics and Nanotechnology at Georgia Tech
345 Ferst Drive, Atlanta GA, 30332

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