Combined type pressure gauge, and manufacturing method of combined type pressure gauge

A manufacturing method of a combined type pressure gauge including a capacitive diaphragm pressure gauge and a Pirani pressure gauge, the manufacturing method comprising:

• a groove-forming step of forming a first groove portion for forming a diaphragm of the capacitive diaphragm pressure gauge on a first surface side of a first substrate, and a second groove portion, which is positioned adjacent to the first groove portion, for forming a filament of the Pirani pressure gauge, on the first surface side of the first substrate, and
• a bonding step of bonding a second substrate having an electrode to the first substrate so as to at least cover the first groove portion on the first surface side of the first substrate, to seal hermetically the inside of the first groove portion and not to seal hermetically the inside of the second groove portion, wherein the second substrate is joined to the first substrate so that a surface of the second substrate where the electrode is formed faces a bottom surface of the first groove portion,
• the manufacturing method furthermore comprising the steps of:
• forming a third groove portion in a region opposite to the first groove portion on a second surface side of the first substrate opposite to the first surface, before the groove-forming step, between the groove-forming step and the joining step, or after the joining step, and
• forming the filament in the second groove portion after the groove-forming step, and
• wherein the first groove portion and the third groove portion are formed so that a region between the bottom surface of the first groove portion and a bottom surface of the third groove portion constitutes the diaphragm.