Process for producing successive stages of a charge coupled device

A process for producing successive stages of a charge coupled device on a semiconductor substrate comprising the steps of:

• a. forming a layer of insulating material on a semiconductor substrate;
• b. forming a layer of a conductive material on said layer of insulating material;
• c. forming an etchable mask over portions of said layer of a conductive material, said etchable mask being etchable by different etches than said layer of a conductive material, said etchable mask having lateral edges disposed along selected edges of closely spaced narrow openings to be formed in said layer of a conductive material;
• d. forming a layer of protective material over exposed portions of said layer of a conductive material, said layer of protective material having lateral edges which overly in one-to-one relation the lateral edges of said etchable mask;
• e. etching said lateral edges of said etchable mask to expose unprotected portions of said layer of conductive material;
• f. etching the exposed portions of said layer of a conductive material down to the surface of said layer of insulating material;
• g. etching the exposed edges of said etchable mask a second time to expose additional unprotected portions of said layer of conductive material;
• h. forming another layer of protective material over the exposed portions of said layer of conductive material;
• i. etching the exposed edges of said etchable mask a third time to expose further unprotected portions of said layer of conductive material;
• and
• j. etching the then exposed portions of said layer of conductive material down to the surface of said layer of insulating material, thereby producing narrow segments of said conductive material on said layer of insulating material.