Method for a treatment to deposit a barrier coating

Method for treating in an enclosure an inner surface of a container made from polymer material in order to deposit a barrier coating there on, comprising:

• inserting the container into the enclosure,
• introducing a precursor gas into the container, wherein the precursor gas is intended, once transformed into the plasma state, to be deposited at least partially on the inner surface of the container in order to constitute the coating, the method being characterized in that it furthermore comprises:
• transforming the precursor gas into the plasma state by a combination of excitations comprising a main excitation by means of electromagnetic waves comprising microwaves, and a secondary excitation by means of an electrical discharge of alternating voltage having a frequency of between 1 kHz and 15 MHz, wherein the secondary excitation stabilizes the plasma state generated by the main excitation, wherein the excitation by means of electromagnetic waves comprising microwaves and the excitation by means of an electrical discharge of alternating voltage are carried out simultaneously during a treatment phase known as a plasma phase, and wherein a power of the main excitation is greater than a power of the secondary excitation.