Provided is a method of fabricating a semiconductor device, including the following steps. A first seal ring and a second seal ring that are separated from each other are formed on a substrate. A protective layer covering the first seal ring and the second seal ring is formed on the substrate. The protective layer between the first seal ring and the second seal ring includes a concave surface. The protective layer at the concave surface and a portion of the protective layer on the first seal ring are removed to form a spacer on a sidewall of the first seal ring, and form an opening in the protective layer. The width of the opening is greater than the width of the first seal ring, and the opening exposes a top surface of the first seal ring and the spacer.