A galvanic isolation capacitor device includes a semiconductor substrate and a PMD layer over the semiconductor substrate. The PMD layer has a first thickness. A lower metal plate is over the PMD layer and an ILD layer is on the lower metal plate; the ILD layer has a second thickness. A ratio of the first thickness to the second thickness is between about 1 and 1.55 inclusive. A first upper metal plate over the ILD layer has a first area and a second upper metal plate over the ILD layer has a second area; a ratio of the first area to the second area is greater than about 5. The galvanic isolation capacitor device can be part of a multi-chip module.