Altium controlled impedance calcs = 1.4mil track!?!?

Hi folks.

This is my first attempt at a four layer board and first board involving high speed signalling (USB 3.0).

The spec sheet for my USB 3.0 hub component (TSUB8020B) recommends controlled impedance of 90Ω +/- 10%. I've plugged these figures into Altium and it's recommending track widths of 0.036mm (about 1.4mils). The board house I hope to use (Elecrow) can only go to 6mils with 8mils recommended so I've either got my board setup wrong or need to go to a significantly better board house?

This is also my first attempt at defining a proper layer stack and could very likely have made a mess of it. I just picked the Altium template for a four layer board.

Can anyone advise if I've gotten something configured wrong or if these figures are realistic?

Thanks

Tommy

A 90 ohm line above 0.2 mm FR4 substrate would have about 0.1 mm (4 mils) width. But there's no single ended 90 ohm transmission line in USB3, I believe.

Your starter for 10.....
https://www.usb.org/developers/presentations/pres0410/1-4_SSUSB_DevCon_LayoutRouting_Heck.pdf

change the stack up for a thicker trace width and a decent spacing , you can use 8/8 ( width / spacing ) with 6 mil gap from reference plane,fr4 , 1 oz copper , etc , I hope . check with your PCB fabricator for exact values .
I think no PCB manufacturer is available for 1.4 mils width.