Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-10-18
2004-10-05
Brooke, Michael S. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000
Reexamination Certificate
active
06799839
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure provided with a through hole, which is formed by silicon (Si) semiconductor base plate and others, and also, relates to a method for manufacturing such structure. More particularly, the invention relates to the structure, which is preferably used for a thermal recording head, an ink jet recording head, or the like used for a printer or other printing apparatus, and also, the invention relates to the liquid discharge head and apparatus using such structure.
2. Related Background Art
A structure provided with a through hole is used in various fields. For example, the ink jet recording head used for an ink jet printer or the like that performs recording by discharging ink, uses a structure formed by silicon semiconductor base plate and others provided with a through hole. Hereinafter, by way of example, the description will be made of the structure having a through hole for an ink jet recording head that discharges ink by the application of thermal energy.
For the ink jet recording head that utilizes thermal energy, liquid is given thermal energy generated by heat generative resistive member (heater), thus selectively creating bubbling phenomenon in liquid so as to discharge ink liquid droplet from the discharge port by means of energy exerted by such bubbling. The ink jet recording head of the kind has many numbers of fine heat generating resistive members arranged on a silicon semiconductor base plate or the like in order to enhance recoding density (resolution), and further, each of the discharge ports is arranged to face each of the heat generating resistive members per heat generating resistive member. Then, the driving circuit and peripheral circuits are also arranged on the silicon semiconductor base plate to the heat generating resistive members, respectively.
FIG. 8
is a cross-sectional view that shows the structure of the ink jet recording head of the kind.
As shown in
FIG. 8
, on one main surface of the silicon base plate
100
of an ink jet recording head, there are laminated a field oxide film (LOCOS oxide film)
101
, the BPSG (boro-phospho-silicate-glass) layer
102
, which is formed by the non-pressure CVD (chemical vapor development) method, and the silicon oxide film
103
, which is formed by the plasma CVD method. Thus, the heat generating resistive member (heater)
110
is formed on the silicon oxide film
103
. Further, the discharge port
140
is arranged to face the heat generating resistive member
110
. In
FIG. 8
, only one heat generating resistive member
110
and only one discharge port
140
are represented. Actually, however, several hundreds of heat generating resistive members and discharge ports are provided for an ink jet recording head. These heat generating resistive members are arranged on one single silicon base plate
100
at designated intervals (40 &mgr;m, for instance) in the direction perpendicular to the surface of FIG.
8
.
Further, in order to protect the heat generating resistive member
110
and others, the silicon nitride film
104
, which is formed as a passivation layer by the plasma CVD, is provided for the entire surface of the aforesaid main surface of the silicon base plate
100
, including above the heat generating resistive member
110
. On the portion of the surface of the silicon nitride film
104
, which corresponds to the heat generating resistive member
110
, tantalum (Ta) film
105
is formed as a cavitation proof layer in order to prevent the silicon nitride film
110
from being deteriorated by the cavitation phenomenon due to bubbles generated in ink. In this respect, the surface of the main surface of the silicon base plate
100
on the side having no heat generating resistive member
110
formed is covered by thermal oxidation film
106
.
The discharge port
140
is formed on the resin covering layer
130
that covers the aforesaid main surface of the silicon base plate
100
. There is a space formed between the resin covering layer
130
and silicon nitride film
104
, and the tantalum film
105
as well. In this space the liquid (ink) that should be discharged from the discharge port
140
is filled. This space is called a liquid chamber
150
.
The ink jet head thus structured is arranged to generate heat when the heat generating resistive member
110
is energized, and create bubbles by such heat in discharge liquid in the liquid chamber
150
, hence discharging liquid droplets from the discharge port
140
by the acting force of such bubbles thus created. In order to perform recording continuously, discharge liquid (ink) must be supplied to the liquid chamber
150
in an amount corresponding to the amount of liquid that has been discharged from the discharge port
140
. However, the discharge port
140
is arranged near a recording medium, such as paper, and also, the gap between the discharge port
140
and the heat generating resistive member
110
is set minutely. Therefore, it is made difficult to supply discharge liquid into the liquid chamber
150
from the side where the heat generating resistive member
110
is formed for the silicon base plate
100
. Here, as shown in
FIG. 8
, a supply port
120
that penetrates the silicon base plate
100
is provided to enable discharge liquid to flow in the direction indicated by an arrow in FIG.
8
through the discharge port
120
for supplying it into the liquid chamber
150
. The supply port
120
is formed with etching the silicon base plate
100
.
Now, the thickness of the silicon base plate
100
is several hundreds of &mgr;m in general, and if it is intended to etch the silicon base plate
100
for the formation of the supply port
120
from the main surface where the heat generating resistive member
110
is formed, each layer and the heat generating resistive member
110
formed on this main surface are damaged unavoidably, because it takes a long time to complete such etching even under condition established to selectively etch only the silicon base plate
100
. Therefore, for the formation of the supply port
120
, the silicon base plate
100
is etched from the main surface where no heat generating resistive member
110
is formed. In this case, too, if etching solution should flow into the side where the heat generating resistive member
110
is formed when the penetration of the supply port
120
is completed, there is a fear that damage is given to the heat generating resistive member
110
, as well as to each of the other layers. Now, therefore, on the main surface of the silicon base plate
100
on the side where the heat generating resistive member
110
is formed, the layer that becomes an etching stopper is formed in advance on the position where the formation of the supply port
120
is expected. In this manner, it is arranged to prevent etching solution from flowing into the side where the heat generating resistive member
110
is formed.
For the area where the supply port
120
is formed for the one shown in
FIG. 8
, the filed oxide film
101
, the BPSG layer
102
, and the silicon oxide film
103
are not provided, but in place thereof, the silicon nitride film
107
, which is formed by the reduced pressure CPD method, is provided. The silicon nitride film
107
is patterned and provided so that it is arranged only for the formation area of the supply port
120
and around it. The edge portions thereof are sandwiched between the field oxide film
101
and the silicon oxide film
102
. In the formation area of the supply port
120
, the silicon nitride film
107
is directly deposited on a thin oxide film
108
of the surface of the silicon base plate
100
. The silicon nitride film
104
, which is formed by the plasma CVD method, is also formed on the silicon nitride film
107
, which is formed by the reduced pressure CVD method.
As described later, in the last stage of etching, the silicon nitride film
107
is exposed to the bottom face of the supply port
120
thus formed. Here, if the silicon nitride film
107
and silicon nitride
Hayakawa Yukihiro
Momma Genzo
Brooke Michael S.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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