Patent Publication Number: US-6209993-B1

Title: Structure and fabricating method for ink-jet printhead chip

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 87108391, filed May 29, 1999, the full disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink-jet printer. More particularly, the present invention relates to a method for fabricating an ink-jet printhead chip. 
     2. Description of the Related Art 
     In a conventional printhead chip, ink slots are formed on a silicon substrate. Since the silicon substrate is thick, the ink slots are long. As a result, a measurable resistance is generated when inks flow through the ink slots. The frequency response of the printhead chip is limited by the resistance. Furthermore, the ink slots may be clogged by overflow paste when the printhead chip adheres to an ink cartridge. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a method for fabricating an ink-jet printhead chip that reduces a resistance when inks flow through ink slots and prevents the ink slots from clogging. 
     To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method for fabricating an ink-jet printhead chip. The method includes the following steps. A silicon substrate having a first surface and a second surface is provided. A plurality of grooves is formed in the first surface by an etching process. A plurality of ink slots is formed in each of the grooves. Overflow grooves are formed in the first surface beside the grooves. A plurality of firing chambers is formed on the second surface. Each of the firing chambers is respectively connected to each of the ink slots. 
     In the invention, the ink slots are formed in the groove, thus the length of the ink slot is short. The resistance generated when inks flow through the ink slot is reduced. During the adhesion process, the overflow groove stores redundant paste so that the ink slots are not clogged. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, 
     FIGS. 1A through 1C are schematic, cross-sectional diagrams used to depict steps in a method according to the invention for manufacturing an ink-jet printhead chip; and 
     FIG. 2 is a schematic, cross-sectional diagram of an ink-jet printhead chip formed by the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     FIGS. 1A through 1C are schematic, cross-sectional diagrams used to depict steps in a method according to the invention for manufacturing an ink-jet printhead chip. 
     Referring to FIG. 1A, a silicon substrate  100  having a first surface  10  and a second surface  12  is provided. An etching process is performed on the first substrate  10 , so that a groove  102  is formed. A region  101  for forming an ink slot is defined in the groove  102 . The thickness of the region  101  is about 50 to 200 μm. The preferably thickness of the region  101  is about 70 μm. Since the thickness of the region  101  is thinner than the original thickness of the silicon substrate  100 , a length of a subsequently formed ink slot in the region  101  is short. 
     Referring to FIG. 1B, an ink slot  104  is formed in the region  101 . The step of forming the ink slot  104  includes anisotropic etching, isotropic etching, cutting with a laser or sandblasting. 
     Referring to FIG. 1C, a firing chamber  106  is formed on the second surface  12 . The firing chamber  106  is connected to the ink slot  104 . During a printing process, the firing chamber  106  is filled with ink through the ink slot  104 . 
     FIG. 2 is a schematic, cross-sectional diagram of an ink-jet printhead chip formed by the invention. 
     Referring to FIG. 2, an overflow groove  108  is formed on the first surface  10 . The first surface  10  is for adhering to an ink cartridge. During the adhesion process, redundant paste flows into the overflow groove  108 . Therefore, no paste flows into the groove  102  so that the ink slot  104  is not clogged. 
     As shown in FIG. 2, the firing chamber  106  is enclosed by walls  110  and includes a heater  112 . A nozzle plate  114  is positioned over the firing chamber  106 . The firing chamber  106  mentioned above is an example used for description in the invention. Any kind of firing chamber is suitable for the invention. 
     In a printing process, ink flows into the groove  102  from the ink cartridge, and then the firing chamber  106  is filled with the inks through the ink slot  104 . The ink is vaporized by the heater  112  to form ink droplets. The ink droplets are expelled through the nozzle plate  114  to perform the printing process. 
     In the conventional printhead chip, the ink slots are directly formed on the silicon substrate. Because the silicon substrate is thick, a large surface of the silicon substrate is necessary to form the ink slots. In the invention, the same number of ink slots is formed in a smaller surface of the silicon substrate because the region for forming the ink slots is thinner. As a result, firing chambers of per unit area is increased, and a resolution of the printhead chip is also increased. 
     The ink slots are formed in the thin silicon substrate. The length of the ink slots is short, so that the resistance generated when inks flow through the ink slots is reduced. 
     In the invention, an overflow groove is formed on the surface for adhering to the ink cartridge. When the printhead chip adheres to the ink cartridge, redundant paste flows into the overflow groove so that the ink slots are not clogged. Yield of the printhead is increased. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.