Charge electrode array and combination for ink jet printing and method of manufacture

A method of forming a charge electrode array in a single crystal substrate of (110) orientation for use in an ink jet recording apparatus for controlling the charging of droplets formed from a plurality of streams passing through the charge electrode apertures comprising the steps of:

• forming an insulating layer over the entire substrate;
• forming first diffused regions of the same conductivity type as the substrate through openings in said layer on the front side of said silicon substrate for receiving a bias;
• forming second diffused regions of opposite conductivity as the substrate through openings in said layer on the front side of said silicon substrate for receiving a voltage to control the charging of ink droplets;
• defining contact areas in the first and second diffused regions;
• adding to said insulating layer to cover said first and second diffused regions and defined contact areas;
• forming apertures adjacent said second diffused regions through said front layer, the silicon substrate and said back layer;
• forming third diffused regions in the walls of the apertures connected to said second diffused regions;
• forming an insulating layer over said third diffused regions;
• forming electrical contacts through openings in the front insulating layer on said first and second diffused regions to permit voltages to be applied for operating the charge electrode array.

A method of forming a charge electrode array in a single crystal silicon substrate of (110) orientation for use in an ink jet recording apparatus for controlling the charging of droplets formed from a plurality of liquid streams passing through the charge electrode apertures comprising the steps of:

• forming an oxide layer over the entire substrate;
• coating the surface of the substrate to permit exposure of a first group of areas on the face of the substrate;
• exposing and developing said first areas;
• diffusing a first dopant into the exposed first areas of the same conductivity type as the substrate;
• coating the surface of the substrate to permit exposure of a second group of areas;
• exposing and developing said second areas;
• diffusing a second dopant into the exposed second areas having a conductivity type opposite from the conductivity type of the substrate;
• forming an oxide layer over the entire substrate;
• coating the surface of the substrate to permit exposure of the first and second areas;
• exposing and developing said first and second areas;
• placing first, second and third layers on the substrate surface;
• coating the third layer to permit removal of all but a defined triple layer in the first and second areas;
• forming an oxide layer over the entire substrate;
• coating the surface to permit exposure of a third group of areas adjacent the second group of areas;
• exposing and developing said third group of areas to the substrate surface;
• anisotropic etching through the entire substrate in the third areas to the insulating layer on the opposite side of the substrate;
• removing the membrane portion of the insulating layer on the opposite side to form the charge electrode aperture;
• diffusing a third dopant having the same conductivity type as the second dopant in the exposed sidewalls of each aperture, said second and third diffused regions being connected together;
• forming an oxide layer along the side walls to electrically isolate each diffused region and protect against corrosion caused by ink jet passage;
• removing the three layers in said first and second areas to the substrate surface;
• and
• placing a metallization in the first and second areas to provide electrical contacts to permit voltages to be applied for operating the charge electrode array.

A method for fabricating a monolithic unit of a plurality of charge electrodes and nozzles for use in an ink jet recording apparatus formed in a single crystal silicon substrate of (110) orientation comprising the steps of:

• forming an insulating layer over the entire substrate;
• forming first diffused regions through openings in said layer on the front side of said silicon substrate for receiving a bias;
• forming second diffused regions through openings in said layer on the front side of said silicon substrate for receiving a voltage to control the charging of ink droplets;
• defining contact areas in the first and second diffused regions;
• adding to said insulating layer to cover the first and second diffused regions and defined contact areas;
• forming third diffused regions to define the nozzle orifices on the back side of said silicon substrate;
• forming apertures adjacent the second diffused regions through said front layer and the silicon substrate along the contour of said third diffused regions;
• forming fourth diffused regions in the walls of the apertures connected to said second diffused regions;
• forming an insulating layer over said third diffused regions;
• and
• forming electrical contacts through openings in said front insulating layer on said first and second diffused regions to permit voltages to be applied for operating the charge electrode array.

A method for fabricating a monolithic unit of a plurality of charge electrodes, nozzles and synchronization electrodes for use in an ink jet recording apparatus formed in a single crystal silicon substrate of (110) orientation comprising the steps of:

• forming an insulating layer over the entire substrate;
• forming first diffused regions through openings in said layer on the front side of said silicon substrate for receiving a bias;
• forming second diffused regions through openings in said layer on the front side of said silicon substrate for receiving a voltage to control the charging of ink droplets;
• defining contact areas in the first and second diffused regions;
• adding to said insulating layer to cover the first and second diffused regions and defined contact areas;
• forming apertures adjacent said second diffused regions through said insulating layer on the front side and the silicon substrate to the insulating layer on the back side;
• forming third diffused regions in the walls of the apertures connected to said second diffused regions;
• forming nozzle orifices in the insulating layer on the back side with each orifice having approximately the same central axis as the aperture;
• placing a conductive layer on the insulating layer adjacent each nozzle orifice to serve as a synchronization electrode;
• placing a second insulating layer on the conductive layer with the first and second insulating layers being connected at each nozzle orifice;
• forming an insulating layer over said third diffused regions;
• forming electrical contacts through openings in the front insulating layer on said first and second diffused regions to permit voltages to be applied for operating the charge electrode array;
• and
• opening the second insulating layer to expose the conductive layer to permit electrical contact to be formed on the conductive layer.