Mounting substrate wafer, multilayer ceramic substrate, mounting substrate, chip module, and mounting substrate wafer manufacturing method

A method of producing a wafer for mounting substrates, comprising:

• a step of providing a multilayer ceramic substrate including a top-face ceramic layer located at a top face, a bottom-face ceramic layer located at a bottom face, a plurality of top face electrodes extending through the top-face ceramic layer, a plurality of bottom face electrodes extending through the bottom-face ceramic layer, and an intermediate ceramic layer having a plurality of internal electrodes formed therein, the plurality of internal electrodes being internal to the multilayer ceramic substrate and providing electrical connection between the plurality of top face electrodes and the plurality of bottom face electrodes, wherein an inter-electrode-central distance of the plurality of top face electrodes is smaller than an inter-electrode-central distance of the plurality of bottom face electrodes;
• a step of applying a planarization process to at least the top face of the multilayer ceramic substrate so that, when the multilayer ceramic substrate is zoned into a plurality of evaluation regions by the units of 20 mm×20 mm, SFQR (Site Front Least Squares Ranges) in a 20 mm×20 mm evaluation region is equal to or less than 2 μm in at least 50% of the plurality of evaluation regions;
• and
• a step of forming a wiring pattern on the top face of the multilayer ceramic substrate through photolithography, the wiring pattern having a minimum line width which is equal to or less than 2 μm and a minimum line space which is equal to or less than 2 μm;
• wherein,
• the step of providing the multilayer ceramic substrate comprises:
• a step of providing a first green sheet to compose the top-face ceramic layer and a second green sheet to compose the bottom-face ceramic layer;
• a step of subjecting the first and second green sheets to aging;
• a step of, after the aging treatment, forming a plurality of holes defining the plurality of top face electrodes and the plurality of bottom face electrodes in the first and second green sheets;
• a step of providing at least one third green sheet to compose at least one ceramic layer located between the top-face ceramic layer and the bottom-face ceramic layer;
• a step of forming a plurality of holes defining the plurality of internal electrodes in the third green sheet;
• a step of filling the plurality of holes of the first, second, and third green sheets with an electrically conductive material;
• a step of stacking and laminating the first, second, and third green sheets to form a laminated ceramic green sheet;
• and
• a step of firing the laminated ceramic green sheet to form a sintered ceramic body, the sintered ceramic body including internal electrodes to connect a top face and a bottom face, top face electrodes, and bottom face electrodes.