Electronic device, method for producing the same, and oscillator

A method for producing an electronic device comprising:

• forming an underlayer on a substrate;
• forming a functional element on the underlayer;
• forming a transistor on the substrate;
• forming a first insulating layer that covers the functional element and the transistor;
• forming a corrosion-resistant layer that covers the first insulating layer;
• removing the corrosion-resistant layer on the underlayer;
• forming a second insulating layer that covers the corrosion-resistant layer and the first insulating layer;
• etching the second insulating layer to expose the corrosion-resistant layer above the transistor and etching the second insulating layer and the first insulating layer, thereby exposing the underlayer in a shape surrounding at least a part of the functional element;
• etching the exposed corrosion-resistant layer to expose the first insulating layer on the transistor and etching the exposed underlayer, thereby forming an opening in the underlayer;
• removing the first insulating layer on the transistor;
• and
• forming a conductive layer on the transistor and disposed in the opening, wherein the forming of the conductive layer includes forming a titanium layer of a lower surface of the conductive layer.

An electronic device comprising:

• a substrate;
• an underlayer having an opening and being formed on the substrate;
• a functional element provided on the underlayer;
• and
• a surrounding wall forming a cavity that accommodates the functional element, at least a part of the surrounding wall being disposed in the opening,
• wherein a lower surface of the surrounding wall has an asperity.