US Patent 11894477 Electrical device with stress buffer layer and stress compensation layer

An electrical device includes a substrate with a compressive layer, a neutral stress buffer layer and a tensile stress compensation layer. The stress buffer layer and the stress compensation layer may each be formed with aluminum nitride using different processing parameters to provide a different intrinsic stress value for each layer. The aluminum nitride tensile layer is configured to counteract stresses from the compressive layer in the device to thereby control an amount of substrate bow in the device. This is useful for protecting fragile materials in the device, such as mercury cadmium telluride. The aluminum nitride stress compensation layer also can compensate for forces, such as due to CTE mismatches, to protect the fragile layer. The device may include temperature-sensitive materials, and the aluminum nitride stress compensation layer or stress buffer layer may be formed at a temperature below the thermal degradation temperature of the temperature-sensitive material.