Method for manufacturing a spiral spring

Method for manufacturing at least one spiral spring (5) comprising the following successive steps:

• a) providing a substrate (1) extending in a determined plane (P) and bearing a first layer (2) parallel to the determined plane (P),
• b) forming at least one through hole (3) in the first layer (2),
• c) depositing a second layer (4) on the first layer (2), the second layer (4) filling the at least one through hole (3) to form at least one bridge of material (7),
• d) etching the at least one spiral spring (5) in an etching layer (6a) consisting of the second layer (4) or of the substrate (1), the one among the second layer (4) and the substrate (1) in which the at least one spiral spring (5) is not etched forming a support (6b), the at least one bridge of material (7) linking the at least one spiral spring (5) to the support (6b) perpendicularly to the determined plane (P),
• e) eliminating the first layer (2), the at least one spiral spring (5) remaining attached to the support (6b) by the at least one bridge of material (7),
• f) subjecting the at least one spiral spring (5) to at least one thermal treatment,
• g) detaching the at least one spiral spring (5) from the support (6b).