Split a 10xscATAC bam file by cluster

I want to split the PBMC scATAC bam from 10x by cluster id. So, I can then make a bigwig for each cluster to visualize in IGV. The first thing I did was googling to see if anyone has written such a tool (Do not reinvent the wheels!). People have done that because I saw figures from the scATAC papers. I just could not find it. Maybe I need to refine my googling skills.