CN1796130A - Fluid ejection device and method of manufacturing the same - Google Patents

Abstract

The present invention provides a fluid injection device, comprising: a substrate; a fluid cavity formed in the substrate; a structural layer covering the substrate and the fluid cavity; at least one nozzle hole passing through the structural layer and communicating with the fluid cavity; and an opening passing through the structural layer and communicating with the end of the fluid cavity, and the connection between the two constitutes a pressure relief hole. The present invention also provides a method for manufacturing the fluid injection device.

Description

Fluid ejection device and method of manufacturing the same

technical field

The invention relates to a fluid injection device, in particular to a fluid injection device capable of removing residual air bubbles in a fluid cavity and a manufacturing method thereof.

Background technique

In various inkjet printing applications, the improvement of printing quality has always been the goal pursued by all users and manufacturers, and there are many factors that affect the printing quality, among which the stability of ejected ink droplets is a very important part.

Taking the thermal inkjet printer as an example, it mainly uses the bubbles generated by the resistance heating element to squeeze the ink, so that the ink is ejected from the nozzle hole to the recording medium to complete the inkjet process. Therefore, the size and size of the bubbles generated during the process Whether there is accumulation of residual bubbles in the fluid cavity becomes an important factor affecting the stability of inkjet.

In the prior art, the basic structure of the heated fluid ejection device and its inkjet procedure are as follows, taking US Patent No. 6,102,530 as an example, please refer to FIG. 1, the fluid ejection device 10 includes a base 12; 14, which is formed in the substrate 12 by internal etching, as the usefulness of supplying ink; a fluid cavity 16, which is formed in the substrate 12 with anisotropic etching after removing the sacrificial layer and communicates with the manifold 14 as a space for storing ink A structural layer 18 covering the fluid chamber 16 and the substrate 12; a heating element 20 disposed on the structural layer 18 to drive fluid injection; a protective layer 22 covering the heating element 20 and the structural layer 18 and a spray hole 24, which passes through the protective layer 22 and the structural layer 18 and communicates with the fluid cavity 16 to spray fluid.

Next, the inkjet process of the device 10 will be described. As shown in FIG. 2 , first, the heating element 20 above the fluid chamber 16 receives a signal to generate high heat, which instantly vaporizes the ink to form two bubbles 26 and 28. Afterwards, due to the formation of the bubbles The volumes of 26 and 28 continue to expand, so the ink is extruded so that the ink is ejected through the nozzle hole 24 to form ink droplets 30. In an ideal state, the generation rate and size of the two air bubbles 26 and 28 are the same, and the extrusion of the ink The amount of pressure is also the same, so after the ink drop 30 leaves the nozzle hole 24, it will be ejected at an angle perpendicular to the surface of the chip, which will not cause the ink drop to be skewed.

However, the actual operation situation is not as ideal. Please refer to the illustrations of FIG. 3A and FIG. 3B. As shown in FIG. , can not be filled smoothly to the end 34 of the fluid chamber, and so-called residual bubbles 36 are produced. If the residual bubbles 36 are not eliminated, the generation of double bubbles will be seriously affected, resulting in the generation of two bubbles 38 and 40 with different shapes. The ink exerts different degrees of squeezing force, causing the ink droplet 42 to finally exit the nozzle hole 44 in an unoriented direction, as shown in FIG. 3B .

Since the printing quality is good or not, it depends on the accuracy of the ink drop on the paper. If the speed and direction of the ink drop leaving the ejection device 3 cannot be fixed, the ink drop will be different due to the initial velocity and the ejection angle during the flight. The difference in α makes the flying distance of each ink drop different (such as 1 or 1'), resulting in an indeterminate offset d when reaching the paper 2, which seriously affects the printing quality, as shown in Figure 4. The biggest factor causing inkjet misalignment mentioned above is the residual air bubbles accumulated in the fluid chamber.

Therefore, it is necessary to develop a method that can eliminate residual air bubbles to achieve stable inkjet quality.

Contents of the invention

Therefore, the object of the present invention is to provide a fluid ejection device, which is expected to achieve the purpose of eliminating residual bubbles and stabilize the ink ejection quality through the design of the pressure relief hole and the guide channel of the fluid chamber.

In order to achieve the above object, the present invention provides a fluid injection device, comprising: a base; a fluid cavity formed in the base; a structural layer covering the base and the fluid cavity; at least one spray hole passing through the base The structural layer communicates with the fluid cavity; and an opening passes through the structural layer and communicates with the end of the fluid cavity, and the connection between the two forms a pressure relief hole.

According to an example of the present invention, a pressure relief hole is designed at the end of the fluid chamber, so that when the fluid is filled, although residual air bubbles will be generated during the process, these residual air bubbles can be immediately discharged from the pressure relief hole arranged at the end of the fluid chamber, It avoids the possibility of residual bubbles affecting the subsequent generation of double bubbles, and because the pressure relief hole is smaller than the nozzle hole, the flow resistance there is relatively large. During the inkjet process, ink droplets will not be ejected from the pressure relief hole. Unnecessary specks are left on the paper.

The present invention also provides a fluid injection device, comprising: a base; a fluid cavity formed in the base, at least one side of the fluid cavity is formed with a guide channel; and a structural layer covering the base and the fluid On the cavity, and has a flow guiding protrusion extending into the fluid cavity to separate the flow guiding channel from the fluid cavity.

According to another example of the present invention, guide channels are made in the fluid cavity, and these guide channels can accelerate the speed at which the ink flows into the end of the fluid cavity, so that part of the ink first fills the end area in the fluid cavity that is not easy to fill, so as to reduce residual ink. The purpose of bubble generation is to improve print quality.

The present invention also provides a method of manufacturing a fluid ejection device, comprising the following steps: providing a substrate; forming a patterned sacrificial layer on the substrate, and the patterned sacrificial layer is used as a region for forming a fluid cavity; forming a patterned sacrificial layer a structural layer on the substrate and covering the patterned sacrificial layer; forming a manifold through the substrate and exposing the patterned sacrificial layer; removing the sacrificial layer to complete the fabrication of the fluid cavity; and etching the structural layer , so as to form at least one spray hole communicating with the fluid cavity and an opening, wherein the opening passes through the structural layer and communicates with the end of the fluid cavity, and the connection between the two forms a pressure relief hole.

The present invention also provides a method of manufacturing a fluid ejection device, comprising the following steps: providing a substrate; forming a patterned sacrificial layer on the substrate, the patterned sacrificial layer is used as a region where a fluid chamber is to be formed, wherein the patterned One side of the sacrificial layer at least includes a groove; forming a patterned structural layer on the patterned sacrificial layer and filling the groove to form a guide bump; forming a manifold to pass through the substrate and expose the patterning the sacrificial layer; removing the sacrificial layer to form a fluid cavity with the flow guide bump, wherein a flow guide channel is formed between the flow guide bump and the sidewall of the fluid cavity; and etching the structural layer, to form at least one spray hole communicating with the fluid cavity.

Description of drawings

In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, a preferred embodiment is specifically cited below, together with the accompanying drawings, as follows:

FIG. 1 is a schematic cross-sectional view of a prior art fluid ejection device.

Fig. 2 is a schematic diagram of ink ejection of a fluid ejection device in an ideal state.

3A is a schematic diagram of a fluid ejection device when it is filled with fluid.

3B is a schematic diagram of a fluid ejection device ejecting fluid when residual air bubbles exist.

Figure 4 is a comparison chart of different droplet landing points.

5A is a top view of a fluid ejection device according to a first embodiment of the present invention.

5B is a schematic cross-sectional view of the fabrication process of the fluid ejection device before forming the fluid cavity according to the first embodiment of the present invention.

5C is a schematic cross-sectional view of the manufacturing process of the fluid ejection device according to the first embodiment of the present invention before the pressure relief holes and openings are formed.

5D is a schematic cross-sectional view of the fluid ejection device taken along 5D-5D in FIG. 5A according to the first embodiment of the present invention and a schematic cross-sectional view of the manufacturing process after forming the pressure relief holes and openings.

Fig. 6 is a top view of a fluid ejection device according to a second embodiment of the present invention.

Figure 7A is a top view of a fluid ejection device according to a third embodiment of the present invention.

7B is a schematic cross-sectional view of the fabrication process of the fluid ejection device according to the third embodiment of the present invention before forming the guide channel and the fluid cavity.

7C is a schematic cross-sectional view of the fabrication process of the fluid ejection device before forming the nozzle holes according to the third embodiment of the present invention.

7D is a schematic cross-sectional view of a fluid ejection device taken along 7D-7D in FIG. 7A according to a third embodiment of the present invention, and a schematic cross-sectional view of the fabrication process after forming flow guiding channels, fluid chambers and nozzle holes.

Explanation of reference signs

Part of existing technology (Figure 1-Figure 4)

1. 1'～flying distance;

2 ~ paper;

3 ~ injection device;

10 ~ fluid injection device;

12 ~ base;

14 ~ manifold;

16, 32 ~ fluid cavity;

18～Structural layer;

20 ~ resistance heating element;

22 ~ protective layer;

24, 44 ~ nozzle hole;

26, 28, 38, 40 ~ bubbles;

30, 42 ~ droplet;

34 ~ the end of the fluid cavity;

36～residual air bubbles;

α～spray angle;

d～droplet offset.

Part of the embodiment of the present invention (Fig. 5A-5D, Fig. 6 and Fig. 7A-7D)

50, 80 ~ base;

52 ~ manifold;

55～sacrifice layer;

54, 82 ~ fluid cavity;

56, 86, 86'～structural layer;

58～resistance heating element;

60, 88 ~ protective layer;

62, 90 ~ spray hole;

64 ~ pressure relief hole;

66～opening;

68 ~ the end of the fluid chamber;

81～sacrifice layer;

81'～groove;

84 ~ diversion channel.

Detailed ways

Example 1

Please refer to FIG. 5A and FIG. 5D to illustrate the structural features of the fluid ejection device of this embodiment. 5D is a cross-sectional view taken along 5D-5D in FIG. 5A. As shown in Figure 5D, the fluid injection device forms an opening 66 at the end 68 of the fluid chamber 54, the opening 66 passes through the structural layer 56 and communicates with the end 68 of the fluid chamber through the pressure relief hole 64, wherein the pressure relief hole 64 The equivalent radius is smaller than the nozzle hole 62 . Next, as shown in FIG. 5A, in this embodiment, since the substrate is a silicon substrate with a lattice arrangement direction of [110] (the present invention is not limited thereto), the end of the fluid chamber after etching presents a pyramid shape, The opening 66 is rectangular, and the pressure relief hole 64 is triangular.

Next please refer to FIG. 5D to illustrate the detailed structure of the fluid ejection device of this embodiment. The fluid ejection device includes a substrate 50, a manifold 52, a fluid chamber 54, a structural layer 56, a resistance heating element 58, and a protective layer. 60 , a spray hole 62 , a pressure relief hole 64 and an opening 66 .

The structural layer 56 covers the substrate 50 and the fluid cavity 54, the resistance heating element 58 is arranged on the structural layer 56, and is located on both sides of the spray hole 62, the protective layer 60 covers the structural layer 56, and the spray hole 62 passes through the protective layer 60 In communication with the structural layer 56 and the fluid cavity 54 , an opening 66 is formed at an end 68 of the fluid cavity 54 , and a pressure relief hole 64 is formed at the junction of the end 68 of the fluid cavity.

The present invention utilizes the principle of pressure balance to provide another air removal path, that is, a pressure relief hole 64 connected to the outside atmosphere is created at the end of the fluid chamber 68 to eliminate residual air bubbles in the fluid chamber 54. On the other hand, the pressure relief hole 64 The equivalent radius must be less than the nozzle hole 62, so that the flow resistance of the ink in the pressure relief hole 64 is greater than the nozzle hole 62, so that ink droplets can be limited to be ejected from the nozzle hole 62, and can not be ejected from the pressure relief hole 64, so that Avoid unnecessary dots or ink leakage during printing.

The relationship between the flow resistance and the pressure relief hole is described below with Equation (1). Among them, ΔP is the pressure drop of the ink, μ is the viscosity coefficient of the ink, r is the radius of the pressure relief hole, L is the length of the pressure relief hole, Q is the volume flow rate of the ink, R _flow is the flow rate resistance.

ΔP＝(8μL/πr ⁴ )Q＝R _flow Q (1)

From the above equation, it can be seen that under the constant volumetric flow rate (Q), the smaller the radius (r) of the pressure relief hole, the greater the flow resistance ( _Rflow ) produced. 62 is a small design, which is to limit the flow of ink towards the pressure relief hole 64 and prevent ink droplets from being ejected from the pressure relief hole 64 .

Next please refer to FIG. 5B-FIG. 5D to illustrate the fabrication of the fluid ejection device of this embodiment. As shown in FIG. Thickness is roughly between 625～675 microns, then, form a patterned sacrificial layer 55 on the substrate 50, as a region that is predetermined to form a fluid chamber, sacrificial layer is made of borophosphosilicate glass (BPSG), phosphosilicate glass (PSG) for example or silicon oxide material, wherein phosphosilicate glass is the preferred choice, and the thickness of the sacrificial layer is generally between 1-2 microns.

Next, a patterned structural layer 56 is formed on the substrate 50 and covers the patterned sacrificial layer. The structural layer 56 can be a silicon oxynitride layer formed by chemical vapor deposition (CVD). The thickness of the structural layer 56 is about 1.5 ~2 microns, then, form a resistance heating element 58 as a driving fluid on the structural layer 56 and be arranged on both sides of the position where the nozzle hole will be formed in the future, the resistance heating element 58 is made of HfB ₂ , TaAl, TaN or TiN, for example, Among them, TaAl is the preferred choice. Finally, a protection layer 60 is formed on the structure layer 56 .

Next, referring to FIG. 5C, a series of etching processes are started to form the final fluid injection device. First, the backside of the substrate 50 is etched by an anisotropic wet etching method with an etching solution such as potassium hydroxide (KOH) solution, To form a manifold 52 and expose the patterned sacrificial layer, the width of the narrow opening of the manifold 52 is about 160-200 microns, the width of the wide opening is about 1100-1200 microns, and the angle between the inner wall and the horizontal line is about 54.74 degrees, so The etched manifold 52 is in a shape with a width at the bottom and a narrow top. In addition, the manifold 52 communicates downward with a fluid storage tank.

Next, the patterned sacrificial layer is etched with a wet etching method containing a hydrofluoric acid (HF) solution, and then the substrate 50 is etched again with an etching solution such as a potassium hydroxide (KOH) solution to expand the patterned sacrificial layer. The hollowed-out area forms a fluid cavity 54. The substrate 50 of this embodiment uses a silicon substrate with a lattice arrangement direction of [110]. The end of the etched fluid cavity will present a pyramid shape. Finally, please refer to FIG. 5D , sequentially etching the protection layer 60 and the structure layer 56 to form at least one nozzle hole 62 communicating with the fluid cavity 54 .

The key step of the present invention is to etch the structural layer 56 above the end 68 of the fluid chamber 54 while etching the spray hole 62, so as to form a pressure relief hole 64 positioned at the end 68 of the fluid chamber and pass through the structural layer. An opening 66 of 56 forms a path for removing residual air bubbles in the fluid chamber, as shown in Figure 5D, the shape of the pressure relief hole 64 is a triangle as shown in Figure 5A, and the equivalent radius of the pressure relief hole 64 is smaller than that of the spray hole 62, It is about 2 to 30 microns, preferably 4 to 15 microns. The etching process can use plasma etching, chemical gas etching, reactive ion etching or laser etching, and reactive ion etching is the preferred choice. So far, it is completed Fabrication of a fluid ejection device.

Example 2

Please refer to FIG. 6 and FIG. 5D to illustrate the structural features of the fluid injection device of this embodiment, wherein FIG. 5D is a cross-sectional view taken along 5D-5D in FIG. 68 forms an opening 66, the opening 66 passes through the structural layer 56 and communicates with the end of the fluid chamber 68 through the pressure relief hole 64, wherein the equivalent radius of the pressure relief hole 64 is smaller than the spray hole 62, and then as shown in Figure 6, because The base 50 of the present embodiment selects a silicon base material whose lattice arrangement direction is [100], so the end of the fluid chamber after etching presents a rectangle, the opening 66 is a pyramid, and the pressure relief hole 64 is a triangle. The difference from Example 1 is that in Example 1, a silicon substrate with a lattice arrangement direction of [110] is selected, while in this embodiment, a silicon substrate with a lattice arrangement direction of [100] is selected.

The structural design and manufacturing steps of the fluid injection device in this embodiment are substantially the same as those in Embodiment 1, only the shape of the end of the etching fluid chamber will be different due to the selection of silicon substrates with different lattice arrangements (such as [110] or [100]). Differently, Embodiment 1 presents a pyramid shape, while the present embodiment forms a rectangle.

Example 3

Please refer to FIG. 7A and FIG. 7D to illustrate the structural features of the fluid injection device of this embodiment, wherein FIG. 7D is a cross-sectional view of FIG. 7A taken along 7D-7D. As shown in FIG. At least one side is formed with a guide channel 84, which is separated from the fluid cavity 82 by a guide protrusion 86' protruding into the fluid cavity 82, wherein the width of the guide channel 84 is smaller than the width of the fluid cavity 82 half.

Next, please refer to FIG. 7D to illustrate the detailed structure of the fluid ejection device of this embodiment. The fluid ejection device includes a base 80, a fluid chamber 82, a guide channel 84, a structural layer 86, a guide bump 86', a protection layer 88 and an orifice 90 .

The structural layer 86 covers the base 80 and the fluid chamber 82 , the diversion bump 86 ′ is the part of the structural layer 86 protruding into the fluid chamber 82 , the protective layer 88 covers the structural layer 86 , and the nozzle hole 90 passes through the protective layer 88 It communicates with the structural layer 86 and with the fluid cavity 82 .

According to the capillary principle of the present invention, the guide channel 84 is made in the fluid chamber 82. The guide channel 84 can accelerate the speed at which the ink flows into the end of the fluid chamber, so that part of the ink first fills the end area of the fluid chamber 82 that is not easy to fill. , in order to achieve the purpose of reducing the generation of residual air bubbles and improve the printing quality.

The above-mentioned capillary principle can be explained by equation (2), where ΔP is the driving pressure of the ink, σ is the surface tension of the liquid, r is the equivalent radius of the flow channel, and α is the angle between the fluid chamber and the ink.

ΔP＝(2σ/r)cos(α) (2)

It can be seen from the above equation that the equivalent radius (r) of the guide channel 84 in the fluid chamber must be less than half of the width of the fluid chamber 82, so that the driving force (σ) of the ink in the guide channel 84 is greater than that of the fluid chamber 82, so that the ink can The end of the fluid cavity 82 is filled in advance through the guide channel 84 to reduce the generation of residual air bubbles.

Next please refer to FIG. 7B～FIG. 7D to illustrate the fabrication of the fluid ejection device of this embodiment. As shown in FIG. 7B, a substrate 80, such as a silicon substrate, is provided. The thickness of the substrate 80 is about 625-675 microns, and then, forming A patterned sacrificial layer 81 including a pair of grooves 81' is on the substrate 80. The sacrificial layer can be made of borophosphosilicate glass (BPSG), phosphosilicate glass (PSG) or silicon oxide material, wherein phosphosilicate glass is used as Preferably, the thickness of the sacrificial layer is about 1-2 microns.

Next, a patterned structural layer 86 is formed on the patterned sacrificial layer 81 and filled into the groove 81' to form a pair of flow guiding bumps 86'. The structural layer 86 can be formed by chemical vapor deposition (CVD). The thickness of the silicon oxynitride layer and the structural layer 86 is about 1.5-2 microns. Finally, a protection layer 88 is formed on the structural layer 86 .

Next, referring to FIG. 7C , the patterned sacrificial layer 81 is etched by a wet etching method containing a hydrofluoric acid (HF) solution, and then the substrate 80 is etched again by a wet etching method using an etching solution such as a potassium hydroxide (KOH) solution. , to expand the hollowed-out area of the patterned sacrificial layer 81 to form a fluid chamber 82 with a guide bump 86 ′, wherein a flow guide channel 84 is formed between the guide bump 86 ′ and the side wall of the fluid chamber 82 , In this embodiment, guide channels 84 are respectively formed on both sides of the fluid cavity 82, but the present invention is not limited thereto, as long as a guide channel is formed on at least one side of the fluid cavity, part of the ink can be filled into the fluid cavity first. In the end area, the effect of reducing the generation of residual bubbles is achieved. The shape of the diversion bump 86 ′ includes rectangle or zigzag, and the width is about 1-3 microns, while the width of the diversion channel 84 is less than half of the width of the fluid cavity, etc. The effective radius is about 2 to 35 microns. Finally, referring to FIG. 7D, the protective layer 88 and the structural layer 86 are sequentially etched to form at least one nozzle hole 90 communicating with the fluid chamber 82. The etching process can use plasma etching, chemical Gas etching, reactive ion etching or laser etching, and reactive ion etching is the preferred choice, so far, the fabrication of a fluid ejection device is completed.

The present invention has been disclosed as above with preferred embodiments, however, it is not intended to limit the present invention, those of ordinary skill in the art can certainly make changes and modifications without departing from the spirit and scope of the present invention, therefore The scope of protection of the present invention should be defined by the appended claims.

Claims (21)

1. A fluid ejection device comprising: a base; a fluid chamber formed in the base; a structural layer covering the base and the fluid cavity; at least one orifice passing through the structural layer and communicating with the fluid cavity; and An opening passes through the structural layer and communicates with the end of the fluid chamber, and the connection between the two forms a pressure relief hole. 2. The fluid ejection device of claim 1, wherein the shape of the fluid chamber end and the opening includes a pyramid and a rectangle, and the shape of the pressure relief hole includes a triangle. 3. The fluid ejection device of claim 1, wherein the equivalent radius of the pressure relief hole is smaller than the orifice. 4. The fluid ejection device of claim 1, wherein the equivalent radius of the pressure relief hole is about 2-30 microns. 5. A fluid ejection device comprising: a base; a fluid cavity formed in the base, at least one side of the fluid cavity is formed with a guide channel; and A structural layer covers the base and the fluid cavity, and has a flow guiding protrusion extending into the fluid cavity to separate the flow guiding channel from the fluid cavity. 6. The fluid ejection device as claimed in claim 5, further comprising flow guiding channels formed on two sides of the fluid cavity. 7. The fluid ejection device of claim 5, wherein the shape of the flow guide bump comprises a rectangle or a zigzag. 8. The fluid ejection device of claim 5, wherein the width of the flow guide bump is about 1-3 microns. 9. The fluid ejection device of claim 5, wherein the width of the flow guide is less than half of the width of the fluid cavity. 10. The fluid ejection device of claim 5, wherein the equivalent radius of the flow guide is about 2-35 microns. 11. A method of manufacturing a fluid ejection device, comprising the steps of: provide a base; forming a patterned sacrificial layer on the substrate, and the patterned sacrificial layer serves as a region where a fluid chamber is intended to be formed; forming a patterned structural layer on the substrate and covering the patterned sacrificial layer; forming a manifold through the substrate and exposing the patterned sacrificial layer; removing the sacrificial layer to complete fabrication of the fluid cavity; and Etching the structural layer to form at least one nozzle hole communicating with the fluid chamber and an opening, wherein the opening passes through the structural layer and communicates with the end of the fluid chamber, and the connection between the two forms a Pressure relief hole. 12 . The method of manufacturing a fluid ejection device according to claim 11 , wherein the shape of the end of the fluid chamber and the opening includes a pyramid or a rectangle, and the shape of the pressure relief hole includes a triangle. 13 . 13. The method of manufacturing a fluid ejection device according to claim 11, wherein the structural layer comprises silicon oxide, silicon nitride or a combination thereof. 14. The method of manufacturing a fluid ejection device according to claim 11, wherein the equivalent radius of the pressure relief hole is smaller than that of the injection hole. 15. The method of manufacturing a fluid ejection device according to claim 11, wherein the equivalent radius of the pressure relief hole is about 2-30 microns. 16. A method of manufacturing a fluid ejection device comprising the steps of: provide a base; forming a patterned sacrificial layer on the substrate, the patterned sacrificial layer is used as a region where a fluid chamber is predetermined to be formed, wherein one side of the patterned sacrificial layer includes at least one groove; forming a patterned structure layer on the patterned sacrificial layer and filling the groove to form a flow guiding bump; forming a manifold through the substrate and exposing the patterned sacrificial layer; removing the sacrificial layer to form a fluid cavity with the flow guide bump, wherein a flow guide channel is formed between the flow guide bump and the side wall of the fluid cavity; and The structural layer is etched to form at least one spray hole communicating with the fluid chamber. 17. The method of manufacturing a fluid ejection device according to claim 16, wherein the patterned sacrificial layer includes a pair of grooves, and the structural layer fills the pair of grooves to form a pair of guide bumps on both sides of the fluid chamber. 18. The method of manufacturing a fluid ejection device according to claim 16, wherein the shape of the flow guiding protrusion comprises a rectangle or a zigzag. 19. The method of manufacturing a fluid ejection device as claimed in claim 16, wherein the width of the flow guiding bump is about 1-3 microns. 20. The method of manufacturing a fluid ejection device according to claim 16, wherein the width of the flow guiding channel is less than half of the width of the fluid cavity. 21. The method of manufacturing a fluid ejection device as claimed in claim 16, wherein the equivalent radius of the guide channel is about 2-35 microns.

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