Backdoor Roth IRA

This will be my first year doing a back door Roth IRA with fidelity. I understand how the process works. My question is, when I put the money in to a traditonal IRA account, what is a settlement fund I can put money into so it does not accrue any interest prior to me converting it to the Roth. I know it takes a few days for the money to settle and don’t want it to accrue any interest during that time. Please provide a fund tracker I can use to keep the money in until I move it to my Roth IRA. Thanks for your help!