High energy gammas have a relatively low cross section, most are going to pass right through the chip. If you add a too little shielding, or don’t layer shielding appropriately you are going to stop more gammas but produce lower energy x-rays from the shielding, which have a higher cross section, potentially increasing your chip dose.
Would it be possible to create a "skip" EM shield that does the opposite - increasing the energy of the gamma rays thereby reducing the likelihood of stopping them?
No idea how. Energies of most chemical bonds / electrons around atoms are not very high, not sufficient to emit proper gamma rays AFAICT. High-energy gamma rays are produced in nuclear reactions. While "clean" nuclear reactions that emit only gamma rays and not neutrons do exist, they are very high-energy and thus hard to initiate, and I don't think it would be easy to capture the energy of incoming gamma efficiently enough.