The design of capacitor structures have great impact on capacitance density, parasitic capacitance, routability, and matching quality of capacitor network in a SAR ADC, which may affect power, performance, and area of the whole data converter. Most of the recent studies focused on common-centroid placement and routing optimization of the capacitor network. Only few of them investigated the structures of highly integrated capacitors. In this paper, a novel mortise-tenon metal-oxide-metal capacitor structure is proposed, which has the advantages of high capacitance density and small parasitic capacitance. Based on the proposed structure, an integer-linear-programming based capacitor sizing and routing parasitic matching method is further introduced. Experimental results show that the proposed structure and method can achieve the best capacitance density and matching quality of the capacitor network in a SAR ADC.