Q&As.pdf

QUESTION 1: How many power supplies are required, one with switching or three?

ANSWER 1: NASA is looking for a minimum of three targets and a minimum of two DC sputter supply with switching. NASA may opt to add a third DC power supply so this should be in the system configuration or addable as an option.

QUESTION 2: The solicitation states, “the system must be able to deposit on multiple substrates so that all substrates (also called ‘wafers’) in a run.” Do you mean multiple substrates in a run or one at a time?

ANSWER 2: While NASA describes a system configuration in the SOW that provides for multiwafer depositions at one time (or, for example, multiwafer for 4”, single wafer for 8”), NASA is considering system configurations proposed by the vendor that best achieve the specifications for thickness uniformity and reproducibility.

QUESTION 3: The solicitation states, “the system will be equipped with a load lock to reduce the water and oxygen levels present in the deposition chamber to suitably low partial pressure levels that oxygen incorporation into the elemental films (of such materials as Nb, Ti, Mo, Al) are negligible.” Do you want LL to be pumped by an oil based mechanical pump or dry pump or turbo based pumping system or a cryo pump? Do you need multiple substrates to be transferred from the LL to deposition chamber or one at a time?

ANSWER 3: NASA is anticipating a UHV load lock (turbo or cryo) but will consider the vendor’s preferred configuration.

QUESTION 4: The solicitation states, “the vacuum system will be capable of electron-beam deposition of films of Au with uniform film thickness (+/-2% across a 100 mm wafer, with 0.5 cm exclusion zone at the edge of the wafer, and +/-1% wafer to wafer).” Do you need to monitor the thickness of Au using the thickness monitor?

ANSWER 4: NASA is not anticipating a thickness monitor in the baseline design but this can be suggested as an option. (There is some language in the SOW that suggests Au will be deposited but due to the cost of sputter targets, NASA does not anticipate Au being deposited in this system to start out).

QUESTION 5: The solicitation states, “the vendor shall supply DC power supplies for each cathode capable of up to 0.5 to 10 kW power output.” How many cathodes?

ANSWER 5: NASA expects a minimum of three cathodes.

QUESTION 6: The solicitation states, “NASA GSFC will obtain a system capable of depositions on 4”, 6”and 8” wafers.” Does it mean to have a system, which is capable of deposition over 8” round wafers? If so, LL will have to handle 8” wafers. Additionally, the solicitation states, “the preferred cathode is 5”x15” rectangular cathode.” If you are looking at

4” wafers, 15” is an overkill but if it is 8” wafer, 15” is must. Please clarify.

ANSWER 6: NASA expects 8” capability for both load lock handling and suitable cathodes for wafer deposition.

QUESTION 7: Would you consider RF Plasma Cleaning instead of Ion Cleaning?

ANSWER 7: NASA will consider RF plasma cleaning as well as ion cleaning.

QUESTION 8: Do you require Automatic Load Lock ? On a planetary rotation system, only one wafer will be loaded at a time, and wafer size change requires retrofit for upgrade.

ANSWER 8: NASA requires an automatic load lock but hardware change out for the various substrate sizes is allowable.

QUESTION 9: How many cathodes do you intend to use?

ANSWER 9: NASA requires a minimum of three cathodes.

QUESTION 10: Any preference on the Ebeam gun size for Au? Would this be a multi-pocket or rotating trough?

ANSWER 10: The system is sputter only and there is no requirement for an e-beam hearth.

QUESTION 11: Do you need substrate bias? It is mentioned in the RFQ, but it could be referring to the ion source.

ANSWER 11: NASA will consider a system where substrate bias during deposition is available – either as a baseline configuration or through optional modification of hardware.

QUESTION 12: Will the ion source be used during Ebeam deposition in addition to the wafer cleaning? Just to confirm, the ion source is RF powered?

ANSWER 12: The ion source will be used for cleaning of the substrates prior to deposition. It is expected to be an RF source.

QUESTION 13: Can you explain the film layer sequence? This is important to understand for the system configuration.

ANSWER 13:

The anticipated use of the tool is for loading either bare oxidized Si substrates or substrates with wiring layers buried under a capping oxide layer with micron-scale vias down to the wiring layer. The substrate will be precleaned followed by addition of Nb to a circuit as a wiring layer. The requirements for the Nb to be uniform thickness, stress tunable, reproducible, and low particulate apply to the sputtered layers made by the system.

QUESTION 14: You are asking for minimum of four 4” wafers in a planetary. You are also asking for a loadlock. Do you expect to load all four wafers at one time? Or one at a time?

ANSWER 14: NASA is considering both configurations. The critical specifications are achieving the thickness uniformity on all the wafers and reproducibility of the target thickness of the sputtered film from wafer to wafer.

QUESTION 15: You are asking for an ebeam unit for evaporation of Au. Is this a single pocket system or multi pocket? If multipocket how many pockets and what size pockets? How thick is the Au film to be?

ANSWER 15: The system is sputter only. The ebeam reference is a typo. There is no e-beam unit needed on this tool.

QUESTION 16: It states that NASA GSFC will obtain a system capable of deposition on 4”, 6” and 8” wafers. This is in contradiction with the request for 4” wafers above. If you want to use

6” and 8” wafers is this one wafer at a time without the use of the loadlock?

ANSWER 16: NASA expected that the loadlock would also accommodate the larger substrates with different tooling provided by the vendor.

QUESTION 17: By Plasma Clean – do you mean ion beam cleaning?

ANSWER 17: The chamber can be configured with either plasma or ion beam cleaning. NASA is looking for uniform clean, low particle counts. NASA will consider the vendor’s ideas for what the best configuration is.

QUESTION 18: It is not clear if you are asking the vendor to provide a chiller itself of just the water manifold assembly- please clarify.

ANSWER 18: GSFC can provide chilled water.

QUESTION 19: It is not clear how many magnetrons you want in the deposition chamber-please clarify.

ANSWER 19: Minimum of three targets / two DC power supplies.

QUESTION 20: When you state particle count (<5 identifiable by microscope inspection), do you mean optical microscopy (particles ~1µm or larger)?

ANSWER 20: Yes, optical inspection will be fine for this examination.