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Warning
The workflow described in this post (and the ones referring to it later on) is outdated and no longer recommended, because new versions of SNAP and StaMPS have been released. Please have a look at this updated list of instructions: StaMPS - Detailled instructions
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@FeiLiu
The StaMPS export tool needs two layers: a layer with coregistred images+deburst (layer1) and another layer (layer2) with interferograms which topographic phase is removed.
Layer1 is obtained with backgeocoding+deburst of images.
As the results obtained with the topographic tool are wrong, I created interferograms for individual pairs and then created a stack (layer3).
For example, in case of 5 images, of which 1 master and 4 slaves, i created layer3 in this way:
1) I processed 4 single pairs (backgeocoding, deburst (and possibly subset), interferogram, topographic phase removal, export) and I obtained 4 different results.
2) I created a stack of these 4 results / pairs (with Create stack tool). In this stack, the images must be renamed with a name compatible with what appears in layer1 (for example, if the pair is 29Apr2015 and 22Jul2015, in layer1 you have i_IW1_VV_mst_29Apr2015, q_IW1_VV_mst_29Apr2015, i_IW1_VV_slv_22Jul2015, q_IW1_VV_slv_22Jul2015, in layer3 your renamed image must be i_ifg_VV_29Apr2015_22Jul2015 and q_ifg_VV_29Apr2015_22Jul2015).
After layer3 was created, I used layer1 and layer3 for export into stamps.