The growth of high-quality epilayers is necessary for high-performance HgCdTe infrared detectors. Due to perfect lattice match with HgCdTe, bulk CdZnTe is considered as the ideal substrate. Crystal materials should achieve very high performance in terms of subgrain boundary absence, low dislocation density, homogeneous zinc distribution, and low micro-defect density, which is essential for acquiring excellent image quality. In order to control the quality of HgCdTe epitaxial layer, Sofradir uses CdZnTe crystals grown by itself as the substrate, thereby achieving high performance imaging. In fact, the whole production process can be improved by mastering the entire manufacturing chain from raw materials to focal plane array (FPA) including all front-end and back-end steps. The method for translating the latest process improvements into detector image quality and reliability improvements with a focus on front-end processes (substrates and epitaxial layers) is introduced. Under the collaboration between Sofradir and CEA-LETI, the correlation between substrate microscopic defects and FPA image quality is firstly demonstrated. Though a large number of characterizations for each process step, including IR-microscopy for the substrate inspection, chemical revelation of dislocations and X-ray double-crystal rocking curve mappings for the epitaxial layer, the overall optimization of this process is achieved. Image quality detection in terms of effective pixel rate and excess noise is completed. Finally, in addition to improving the process, understanding how each key step affects the subsequent steps and translates them into the final image quality is helpful for sorting units in the correct process step, which serves yield and product quality. These advantages of the Sofradir′s vertical integration model are demonstrated on the mid-wave infrared and short-wave infrared technologies.