Flow path assembly, valve device, fluid control device, semiconductor manufacturing apparatus and semiconductor manufacturing method using said flow path assembly

A flow path assembly comprising:

• a first flow path member and a second flow path member made of metal defining a fluid flow path connected to each other in a connecting portion;
• a plate-like member provided between the first flow path member and the second flow path member and having a functional portion providing a specific action on a fluid flowing through the fluid flow path;
• and
• an annular seal member made of resin provided between the first flow path member and the second flow path member;
• the first flow path member having a first sealing surface for supporting one end surface of the annular seal member;
• the second flow path member having a second sealing surface that is a flat surface for supporting a surface of the plate-like member, and a third sealing surface for supporting an outer peripheral surface of the annular seal member;
• wherein the annular seal member is crushed by a force acting between the first flow path member and the second flow path member in the connecting portion, an other end surface of the annular seal member is pressed against a back surface of the plate-like member air-tightly or liquid-tightly, the one end surface of the annular seal member is pressed against the first sealing surface of the first flow path member air-tightly or liquid-tightly, and the outer peripheral surface of the annular seal member is pressed against the third sealing surface of the second flow path member air-tightly or liquid-tightly;
• and
• the plate-like member is pressed by the other end surface of the annular seal member so that the surface of the plate-like member is pressed against the second sealing surface of the second flow path member air-tightly or liquid-tightly.