For 1 micron SiO2 (quite thick) to my understanding the best deposition process should be Plasma-Enhanced Chemical Vapor Deposition (PECVD) technique if you would like to reduce the deposition time. Sputtering should also work in this case. I also found that pulsed laser deposition (PLD) technique is also useful for near 1 micron silicon dioxide thickness. The most versatile technique of all is however atomic layer deposition or ALD process but it is nm level adhesion and for 1 micron it might take unfeasibly longer time that may not be sustainable. I am giving relevant papers for all these processes.
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