Three-dimensional memory device with composite charge storage structures and methods for forming the same

A memory device comprising:

• an alternating stack of insulating layers and electrically conductive layers located over a substrate;
• and
• a memory stack structure extending through the alternating stack, wherein the memory stack structure comprises a vertical stack of discrete charge storage elements that are vertically spaced apart from each other located at levels of the electrically conductive layers, a tunneling dielectric layer located on inner sidewalls of the discrete charge storage elements, and a vertical semiconductor channel contacting an inner sidewall of the tunneling dielectric layer,
• wherein each of the discrete charge storage elements comprises:
• a silicon nitride portion including an inner sidewall that contacts an outer sidewall of the tunneling dielectric layer;
• and
• a silicon carbide nitride liner in contact with the silicon nitride portion;
• further comprising silicon oxide blocking dielectric portions located at each level of the discrete charge storage elements, wherein each of the discrete charge storage elements is laterally spaced from a respective one of the electrically conductive layers by a respective one of the silicon oxide blocking dielectric portions;
• wherein each of the discrete charge storage elements further comprises a silicon nitride liner contacting the silicon carbide nitride liner and the outer sidewall of the tunneling dielectric layer;
• wherein the silicon nitride liner of each of the discrete charge storage elements contacts a respective overlying one of the insulating layers, and contacts a respective underlying one of the insulating layers;
• and
• wherein the silicon nitride liner of each of the discrete charge storage elements is thinner than the silicon nitride portion.