Methods for manufacturing a substrate for a liquid jet recording head, liquid jet recording head, and liquid jet recording apparatus

A method of manufacturing a substrate for a liquid jet recording head, said method comprising the steps of:

• providing a polycrystalline silicon substrate;
• forming a first portion of a heat accumulating layer on said substrate, said first portion of said heat accumulating layer having steps in a surface thereof;
• then, by means of a bias ECR plasma CVD technique, forming a second portion of said heat accumulating layer on said surface of said first portion of said heat accumulating layer to flatten said steps in said surface;
• forming a heat generating resistance layer on the flat surface of said second portion of said heat accumulating layer, said heat generating resistance layer having a flat portion constituting a flat heat generating resistance member;
• and thereafter providing on the heat generating resistance layer, a wiring layer comprising spaced apart electrodes between which electrical current is directed through said flat heat generating resistance member for generating heat in response to an electrical signal applied to said electrodes.