Following Gimson's “Pronunciation of English”, I use palato-alveloar fricative for the voiceless and voiced English phonemes represented in the IPA as /ʃ/ and /ʒ/ respectively. I thus follow the description in Gimson (2008: 201) in describing the “palato-alveolar fricative” consonants as being articulated as follows:

“The soft palate being raised and the nasal resonator shut off, the tip and the blade of the tongue make a light contact with the alveolar ridge, the front of the tongue being raised at the same time in the direction of the hard palate and the side rims of the tongue being in contact with the upper side teeth.” Similarly, Roach (1987) says that their place of articulation is partly palatal, partly alveolar, hence the name “palato-alveolar”.

Note that the terms “palato-alveolar” and “post-alveolar” can often be found to be used interchangeably in the literature. I prefer “palato-alveolar” for its clarity and precision while at the same time conceding that the term may be argued to convey a level of precision that may sometimes be hard to defend in view of the fact that there is non-phonemic variation in the articulation of these fricatives, especially with a view to variation across different languages. Gimson (2008: 201) points out that a palatization effect in the articulation of /ʃ/ and /ʒ/ may be more or less pronounced across languages, so there seems to be some degree of variation between languages having these phonemes, i.e some of them showing an articulation that is further back towards the hard palate than others.

sources:
Cruttenden, A., & Gimson, A. C. (2008). Gimson’s pronunciation of English (7th ed). Hodder Education.
Roach, P. (1987). “Rethinking phonetic taxonomy.” In: Transactions of the Philological Society, 85, 24-37.