Fluid ejection systems may operate by ejecting a fluid from nozzles to form images on media and/or forming three-dimensional objects, for example. In some fluid ejection systems, fluid feed holes lead fluid into fluid ejection chambers, and the fluid is expelled from nozzles of a fluid ejection die. The fluid may bond to a surface of a medium and form graphics, text, images, and/or objects.
Fluid ejection dies may deposit fluids onto media (e.g., a print medium) through a fluid feed hole and a nozzle. For instance, a nozzle can include an opening in a thin film portion of a fluid ejection die, and a fluid feed hole can include a portion of the fluid ejection die through which the fluid passes before reaching the nozzle and the media. Some fluid ejection dies have large architectural areas of thin films into which fluid feed holes are formed. These thin films may be susceptible to fluid attack when a fluid contacts the thin films. For instance, boron/phosphorus doped silica glass (BPSG) and/or other poly films may be attacked or etched by fluid if the fluid passes through the thin film (e.g., during a printing process). This can result in degradation or reduced life of fluid ejection dies. For instance, a resistor of the fluid ejection day may be damaged, resulting in an ejection component being unable to fire. Additionally or alternatively, fluid attack of the thin film may result in undercut or voided areas where fluid may cause shorting of circuits.
In contrast, some examples of the present disclosure include protecting thin films from fluid attack using a fluid-attack-resistant material that is formed on the thin films and planarized during a fluid feed hole creation process. For instance, some examples include forming a fluid-attack-resistant material such as tetraethyl orthosilicate (TEOS) and/or a thermal oxide on the thin films and in vias formed in the thin films. The fluid-attack-resistant material may be planarized and subsequently etched, resulting in a fluid feed hole with fluid-attack-resistant sidewalls. A “fluid-attack-resistant material” as used herein, includes a material that is resistant to chemical or other attacks, such as an undesirable material etch, by fluids passing through a fluid ejection die (e.g., fluidic dies, printheads, or other types of apparatuses that may include fluid feed holes through deposited thin films).
The large architectural areas of thin films on some fluid ejection dies can hinder or prevent desired planarization processes. For instance, a fluid ejection die undergoing planarization in a fluid feed hole or dummy structure creation process may experience non-uniform or inconsistent planarization due to existing uneven pattern density of the thin films that is a side effect of the large architectural area. Planarization, for instance, may be desired to smooth a fluid ejection die's surface for preparation and creation of a fluid feed hole or dummy structure for use in an array of fluidic die nodes of the fluid ejection die. Planarization may also be desired when materials that cannot be polished using other methods (e.g., chemical etching, free abrasive polishing, etc.) are used in fluid ejection die fabrication due to size or material make-up. Non-uniform and/or inconsistent planarization may result in incomplete and/or inefficient creation of fluid feed holes and/or dummy structures in the fluid ejection die.
In contrast, some examples of the present disclosure can include smaller architectural areas of those thin films (e.g., as opposed to one large area) that allows for substantially uniform global planarization (e.g., chemical mechanical planarization (CMP)) of the fluid-attack-resistant material. As used herein, “substantially” means that a characteristic (e.g., uniformity) need not be absolute, but is close enough to the absolute characteristic so as to achieve the desired effects of the characteristic.) For instance substantially uniform global planarization means a surface of the fluid ejection die is mostly consistent following planarization but may include inconsistencies below a threshold.
Additionally, a number of dummy structures may make up an array of fluidic die nodes (e.g., along with nodes into which fluid feed holes will be formed) and may facilitate uniform planarization. For example, even though a die may not support a number of nozzles at a pitch of X units (e.g., such as due to fabrication and structural constraints), an increased density of nodes in an array of fluidic die nodes may be achieved by grouping nodes for both fluid feed holes and dummy structures. Such an increased density of nodes may be desirable in order to provide increased uniformity of planarization (such as compared with an implementation in which node density is comparatively lower).
The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 104 may reference element “04” in
Elements shown in the various figures herein can be added, exchanged, and/or eliminated so as to provide a number of additional examples of the present disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the present disclosure and should not be taken in a limiting sense. As used herein, the designator “M”, “N”, “P”, “R”, and “T” particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included with examples of the present disclosure. The designators can represent the same or different numbers of the particular features.
Referring to
Ejection component 101-M may include additional components, such as additional or different metals, metal oxides, dielectrics, and/or other materials for instance. Although not illustrated in
Each ejection component among the plurality of ejection components 101 may be electrically coupled to a first control line 111 by a respective switch 105-1, 105-N (collectively referred to herein as switches 105) among a first group of switches, or a second control line 109 by a respective switch 107-1, 107-P (collectively referred to herein as switches 107) among a second group of switches. In some examples, the first group of switches 105 may be of a different type than the second group of switches 107. For instance, the switches 105 may be N-type switches, whereas switches 107 may be P-type switches. That is, ejection components 101-1 and 101-3 may be electrically coupled to the second control line 111 by P-type switches 105-1 and 105-N, respectively, and ejection components 101-2 and 101-M may be electrically coupled to the first control line 109 by P-type switches 107-1 and 107-P, respectively. As used herein, an N-type switch refers to a device capable of amplifying and/or switching electronic signals using an N-type semiconductor. Examples of an N-type switch may include an N-type field-effect transistor (FET) and/or an N-type metal-oxide-semiconductor field-effect transistor (MOSFET). Examples are not so limited, however, and the plurality of ejection components may be coupled to the control line in other ways. As used herein, a P-type switch refers to a device capable of amplifying and/or switching electronic signals using a P-type semiconductor. Examples of a P-type switch may include a P-type FET and/or a P-type MOSFET. Although switches 107 and 105 are illustrated as P-type switches and N-type switches, respectively, examples are not so limited. For example, switches 107 may be N-type switches and switches 105 may be P-type switches. In another example, switches 107 and 105 may be other types of switches, arranged such that an alternating bias is generated among the ejection components 101.
Referring again to
Fluid ejection die 100 may further include a control circuit 110 to generate an alternating bias among the plurality of ejection components 101 using a plurality of control lines. That is, the control circuit 110 may create an alternating bias among the plurality of ejection components using the first control line 111 and the second control line 109.
Subsequent to the removal of the portion of the thin film materials 208, 203, and 206, a fluid-attack-resistant material 204 can be formed in contact with the thin film materials 208, 203, and 206. For instance, the fluid-attack-resistant material 204 is formed on a top surface of thin film material 206 and in the via 215, resulting in coverage of sidewalls of the thin film materials 208, 203, and 206.
For a seam having a large width (e.g., 30 microns or greater), the planarization process may remove a portion of the fluid-attack-resistant material 204 within the via 215 at approximately a same rate as a portion of the fluid-attack-resistant material 204 is removed above the thin film material 206. This may be undesirable because a resulting layer of the fluid-attack-resistant material 204 may be uneven and may provide less protection (e.g., against printing fluid etch). In contrast, if the seam 214 is narrower (e.g., less than 30 microns wide),material removal at the bottom surface 220 may be slowed, which can prevent uneven planarization. Put another way, the small width can allow for a substantially uniform global planarization of the fluid-attack-resistant material 204. For instance, planarization may include the top surface 218 being removed uniformly with little to no removal of the bottom surface 220 of the seam 214.
At 334, the method 330 can include forming a fluid-attack-resistant material such as TEOS and/or a thermal oxide on the plurality of thin films and in the via. Put another way, the via of less than 50 microns may be formed in the thin films and filled with the fluid-attack-resistant material. In some examples, a seam is formed in the fluid-attack-resistant material during formation of the fluid-attack-resistant material such that the seam is less than 30 microns wide. The seam of less than 30 microns is formed in the fluid-attack-resistant material such that on either side of the seam is less than 10 microns of fluid-attack-resistant material (e.g., 30-micron seam with 10 microns of TEOS on each side). While 50 microns, 30 microns, and 10 microns are used herein, other dimensions may be possible.
The method 330, at 336, can include planariz ng the fluid-attack-resistant material using CMP, as noted above. Because of the substantially uniform pattern density of the vias (e.g., of a threshold size) and the seams, global planarization across a fluid ejection die may be achieved (e.g., a substantially flat surface is achieved). At 338, the method 330 can include forming the fluid feed hole by removing a portion of the planarized fluid-attack-resistant material in the via. For instance, by etching through the fluid-attack-resistant material to a substrate material, a fluid feed hole can be created resulting in a path to a resistor. In some examples, the method 330 can include forming a dummy structure in a different portion of the planarized fluid-attack-resistant material in the via by withholding etching through the different portion. For instance, a different portion can include another location within the planarized fluid-attack-resistant material that was formed in the via.
In some examples, the method 330 can include continuing to form and etch additional thin films following the planarizing and protecting of the susceptible thin films (e.g., using a deposition/photo/etch process), as discussed in relation to 332-338, such as to form a fluid ejection die comprising ejection chambers in fluid communication with the through holes formed at 338. Thus, in some cases, method 330 may include additional layers and/or etches.
For instance, the method 440, at 446, can include globally planarizing the TEOS material using CMP. The global planarization, in some examples can include planarizing a base of each one of the plurality of seams subsequent to planarizing the TEOS formed on the plurality of thin films. For instance, CMP is more efficient with substantially uniform planarization (e.g., global planarization). A smaller seam (due to a smaller via) results in a more uniform planarization rate across a fluid ejection die.
At 448, the method 440 can include forming the array of fluidic die nodes, which includes fluid feed holes and dummy structures. Forming the array of fluidic die nodes can include, for instance as shown at 450, etching through the planarized TEOS material in a portion of the plurality of vias to form fluid feed holes. Forming the array of fluidic die nodes, as shown at 452, can also include withholding etching from a remaining plurality of vias to form dummy structures. For example, withholding etching from a remaining plurality of vias may be accomplished by applying a protective layer, such as a photoresist, over the vias in one case. In some examples, the array of fluidic die nodes is formed in a pattern of fluid feed holes and dummy structures. For instance, the pattern may include a threshold percentage (e.g., 50 to 90 percent) of dummy structures and/or may be determined based on a desired dots-per-inch measure of a printing device and/or fluid ejection device associated with the fluid ejection die. For example, nozzles may be fluidly coupled to the fluid feed holes of the array of fluidic die nodes such that fluid is ejected through the nozzles in compliance with the desired dots-per-inch measure. In some instances, the pattern may be determined based on a pattern density (e.g., the threshold percentage) that results in substantially global planarization.
The dummy structures 521, in some examples, are electrically coupled to a control line or an interconnect. The dummy structures 521 can make up a threshold percentage of the array of fluidic die nodes 560. For example, the threshold percentage of the dummy structures can be between 50 and 90 percent of the array of fluidic die nodes 560. This threshold percentage and/or the pattern of the fluid feed holes 516 may be based on a desired dots-per-inch measure, in some examples. For instance, while the dummy structures 521 and fluid feed holes 516 in
In the foregoing detailed description of the present disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how examples of the disclosure may be practiced. These examples are described in sufficient detail to enable those of ordinary skill in the art to practice the examples of this disclosure, and it is to be understood that other examples may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure.
Filing Document | Filing Date | Country | Kind |
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PCT/US2019/040600 | 7/3/2019 | WO | 00 |