Specific Process Knowledge/Thin film deposition/Temescal/Acceptance Test: Difference between revisions
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=Acceptance test and test results= | =Acceptance test and test results= | ||
[[File:w26 with resist02.jpg|400px|right|thumb|Si wafer with nLOF resist pattern and 10 nm Ti/100 nm Au on top. The side wall is free of deposition]] | |||
In the acceptance test, we tested the vacuum performance, the ion source, and the uniformity of the deposited metal films. | In the acceptance test, we tested the vacuum performance, the ion source, and the uniformity of the deposited metal films. | ||
The uniformity of the ion beam etch was tested on Si wafers with | The uniformity of the ion beam etch was tested on Si wafers with SiO<sub>2</sub> coating of a known thickness. | ||
For metal films, the thickness and for Ti/Ni the sheet resistance uniformity were measured. | For metal films, the thickness and for Ti/Ni the sheet resistance uniformity were measured. | ||
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Side wall coverage was evaluated in SEM for Ti/Au films deposited at normal incidence (what most users require, which gives no side-wall deposition) and with various degrees of tilt. | Side wall coverage was evaluated in SEM for Ti/Au films deposited at normal incidence (what most users require, which gives no side-wall deposition) and with various degrees of tilt. | ||
'''Full acceptance test report here:''' | ===[[:File:Temescal Acceptance Test Results Mar-April-May 2018.pdf|'''Full acceptance test report here:''']] === | ||
== Thickness uniformity == | |||
The thickness uniformity is good both across a single wafer, from wafer to wafer within a batch of 4 wafers and from batch to batch comparing up to 5 batches. This is ensured by the Hula sample holder, which rotates each individual wafer holder around its axis as well as all four wafer holders around the central axis. | |||
We saw less than 3 % variation across a 6" wafer and comparable or lower variation wafer to wafer and batch to batch. | |||
The thickness uniformity was not tested for the 8" sample holder nor for the tilted sample holder. | |||
We cannot guarantee that the batch-to-batch thickness reproducibility will always be below 3 % as there may be more drift over longer times. We check the thickness of a Ti/Au deposition every month and ensure that it is within 10 % of the expected value and so far, within in the first half year of using the instrument, the variation has been much less than 10 %. | |||
== Sheet resistance uniformity == | |||
The sheet resistance varied less than 2 % across a single 6" Ti/Ni coated wafer and less than 1 % from wafer to wafer comparing a total of 4 wafers made in two different batches. | |||
Note that thickness variation will lead to variation in the sheet resistance, so accurate thickness is important for reproducible sheet resistance values. | |||
== Ion source == | |||
We achieved an etch rate of up to 1 nm/min for SiO<sub>2</sub>. The etch rate is strongest in the center, about 15-20% higher than at the edges of a 6" wafer. | |||
The reproducibility was quite good with less than 3% variation wafer-to-wafer within a batch and less than 10 % variation between the two identical batches. | |||
== Vacuum performance == | == Vacuum performance == | ||
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More results in the full report. | More results in the full report. | ||
==Side wall deposition on tilted samples == | |||
The tilted sample holder was tested at approx. 27 °, 45 °, and 53 ° to the normal (53 ° is the max tilt variation for a 6" sample holder - we now have a smaller 2" sample holder that can tilt all the way to perpendicular to the evaporation source). | |||
The side wall deposition was clearly stronger for 53 ° tilt than for 17 ° tilt. | |||