FORMING PRINTHEADS

BACKGROUND

[0001 ] Inkjet printers may include a fluid ejection device, such as a printhead, to eject drops of marking material, such as ink, onto printable media, such as paper. For example, a printhead might eject drops of ink onto the paper while relative movement occurs between the printhead and the paper. In some examples, the drops of ink might be ejected in response to heating the ink, e.g., in examples involving thermal inkjet printheads. In some examples, a printhead might be formed using photoimaging techniques, such as photolithograpy techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figures 1A-1 J are cross-sectional views during various example stages of an example of forming a printhead.

[0003] Figures 2A-2B are cross-sectional views during various example stages of an example of forming a printhead.

[0004] Figure 3 is flowchart of an example of a method of forming a printhead.

[0005] Figure 4 is flowchart of an example of a method of forming a printhead.

DETAILED DESCRIPTION

[0006] Printheads, such as thermal inkjet printheads, sometimes include chambers (e.g., sometimes referred to as firing chambers) that are over resistors. During operation, for example, ink that is received in the firing chambers might be heated by the resistors, e.g., in response to dissipating electrical current in the resistors. Heating of the ink may cause a vapor bubble to form in the ink adjacent to a resistor that ejects ink that is above the bubble from the chamber.

[0007] In some of the examples discussed herein, a metal conductor may be formed over the resistors and over a region between the resistors. An inclined segment of the metal conductor may then be removed from over the region between the resistors. For example, the inclined segment of the metal conductor may be the result of forming the metal conductor over an inclined surface in the region between the resistors that may form while forming the resistors. The metal conductor may sometimes be called a cavitation layer, for example, in that the metal conductor may act to resist the forces generated due to the repeated collapse of the vapor bubbles that are generated in the ink when the ink is heated by the resistors.

[0008] The removal of the inclined segment acts to prevent reflections of electromagnetic radiation, e.g., ultraviolet radiation, from the surface of the inclined segment that may occur during the formation of the firing chambers when the inclined segment is not removed. In some examples, the firing chambers might be formed using photoimaging, such as photolithography. For example,

photoimageable material, such as photoresist, might be formed over the resistors and over the region between the resistors. In some examples, the photoimageable material over the region between the resistors may be exposed to the radiation, while the photoimageable material over the resistors is covered, e.g., using a mask.

[0009] A solvent, e.g., sometimes called a developer, may then be applied to the photoimageable material to remove the photoimageable material over the resistors that was covered to form the firing chambers over the resistors and to leave the photoimagable material between the resistors that was exposed to the radiation and that cannot be removed by the solvent.

[0010] However, in examples where the inclined surface of the metal conductor is not removed from the region between the resistors, the inclined surface may reflect the radiation into the photoimageable material over the resistors that are covered, thereby exposing at least some of the photoimageable material over the resistors to the radiation. As a result, some exposed photoimageable material could remain in the firing chambers over the resistors after applying the solvent, in that the solvent would not remove the exposed photoimageable material. [0011 ] Figures 1A-1 J are cross-sectional views during various example stages of an example of forming a printhead. In Figure 1A, a metal conductor 102 (e.g. a layer, such as a thickness, of a conductive metal material), such as aluminum copper (AICu), is formed over a dielectric 104, such as TEOS (tetraethylorthosilicate). In some examples, metal conductor 102 is formed in direct physical contact with an upper surface 105 of dielectric 104.

[0012] Openings 106 are then formed in metal conductor 102 to expose portions of the upper surface 105. For example, openings 106 may be formed by patterning the metal conductor 102 and removing exposed portions of metal conductor 102. For example, a mask (not shown), e.g., imaging resist, such as photoresist, may be formed over metal conductor 102 and patterned to define the portions of metal conductor 102 for removal. The portions of metal conductor 102 defined for removal are subsequently removed, e.g., by etching, to form openings 106 that may terminate at the upper surface 105. In some examples, the removal process causes the remaining portions 107 of metal conductor 102 to have inclined (e.g., sloped, such as angled) sidewalls 108 that also form the inclined sidewalls of openings 106.

[0013] A resistive material 109 (e.g. a layer, such as a thickness, of resistive material 109), such as tungsten silicide nitride (WSiN), is then formed in openings 106 over dielectric 104 and over the remaining portions 107 of metal conductor 102. In some examples, the resistive material 109 in openings 106 is formed in direct physical contact with the upper surface 105 of dielectric 104, and the resistive material 109 over the remaining portions 107 of metal conductor 102 is formed in direct physical contact with the upper surfaces and the inclined sidewalls 108 of the remaining portions 107 of metal conductor 102.

[0014] In some examples, dielectric 104 might be formed over a semiconductor (not shown), such as silicon. In some examples, other dielectrics (not shown) might be between the semiconductor and dielectric 104.

[0015] In the example of Figure 1 B, resistors 1 10 (e.g., resistors 1 10-1 to 1 10-3) are formed over dielectric 104 from the resistive material 109 in the openings 106 in metal conductor 102. For example, resistors 1 10-1 to 1 10-3 are respectively formed in locations corresponding to the openings 106 in metal conductor 102. Resistors 1 10 and conductor-resistor (e.g., AICu-WSiN) stacks 1 14, including the resistive material 109 over the metal conductor 102, for example, may be formed while removing a portion of the resistive material 109 and a portion of metal conductor 102 from the structure of Figure 1 A to expose surfaces of dielectric 104 in the regions 1 12 between the resistors 1 10 and the stacks 1 14, as shown in Figure 1 B.

[0016] In some examples, the resistors 1 10 and the stacks 1 14 may be formed by patterning resistive material 109 in the openings 106, corresponding to the resistors 1 10, and patterning resistive material 109 over the remaining portions 107 of conductor 102, corresponding to the stacks 1 14. Exposed portions of resistive material 109 in the openings 106 are removed, leaving the resistors 1 10, and the exposed portions of the resistive material 109 and portions of the remaining portions 107 of conductor 102 under the exposed portions of the resistive material 109 are removed, leaving the stacks 1 14, as shown in Figure 1 B.

[0017] For example, a mask (not shown), e.g., imaging resist, such as

photoresist, may be formed over resistive material 109 and patterned to define the portions of resistive material 109 and the portions of the remaining portions 107 of conductor 102 under resistive material 109 for removal. The portions of resistive material 109 and the portions of the remaining portions 107 of conductor 102 under resistive material 109 defined for removal are subsequently removed, e.g., by etching, such as dry etching, leaving resistors 1 10 and stacks 1 14.

[0018] The removal process continues until the portions of the remaining portions 107 of conductor 102 defined for removal are removed. This causes some of dielectric 104 to be removed. The removal of dielectric 104 causes dielectric 104 to have exposed inclined (e.g., sloped, such as angled) surfaces 1 16 (e.g. that may be inclined by about 5 to about 10 degrees from the horizontal in Figure 1 B) in the regions 1 12 between the resistors 1 10 and the stacks 1 14. Note that the inclinations of inclined surfaces 1 16 in Figure 1 B and subsequent figures are not to scale.

[0019] Note that the inclined surfacesl 16 are between adjacent (e.g.,

successively adjacent) resistors 1 10, such as between resistors 1 10-1 and 1 10-2 and between resistors 1 10-2 and 1 10-3. Inclined surfaces 1 16 are, at least in part, due to the removal of the inclined sidewalls 108 of the remaining portions 107 of conductor 102. For example, the removal of resistive material 109 and conductor 102 may form the inclined surfaces 1 16. [0020] In some examples, the conductors 102 in the stacks 1 14 might be electrically coupled to respective ones of the resistors 1 10-1 to 1 10-3. For example, the conductors 102 in the stacks 1 14 might form the return portion of an electrical circuit that supplies current to resistors 1 10-1 to 1 10-3 to cause heating of resistors 1 10-1 to 1 10-3.

[0021 ] A dielectric 120 (e.g. a layer, such as a thickness, of dielectric material), such as silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ) or a combination of silicon carbide and silicon nitride, is formed over the structure of Figure 1 B, as shown in the example of Figure 1 C. Dielectric 120, for example, is formed over resistors 1 10, the exposed dielectric 104, and stacks 1 14. For example, a portion of dielectric 120 is formed over resistors 1 10-1 to 1 10-3 and another portion of dielectric 120 is formed over the exposed inclined surfaces 1 16 of dielectric 104 in the region between successively adjacent resistors 1 10-1 and 1 10-2 and in the region between successively adjacent resistors 1 10-2 and 1 10-3. In some examples, dielectric 120 might be referred to as a passivation material, such as a passivation dielectric, and may at least act to protect underlying structures, such as resistors 1 10-1 to 1 10-3 and dielectric 104 from adverse effects of inks.

[0022] In some examples, the portion of dielectric 120 formed over resistors 1 10- 1 to 1 10-3 is formed in direct physical contact with (e.g., with upper surfaces of) resistors 1 10-1 to 1 10-3, and the portion of dielectric 120 formed over the exposed inclined surfaces 1 16 of dielectric 104 is formed in direct physical contact with the inclined surfaces 1 16 of dielectric 104. In some examples, inclined portions (e.g. inclined segments) 122 of dielectric 120, having inclined surfaces 124, are over (e.g., directly over) and in direct physical contact with the inclined surfaces 1 16 of dielectric 104, as shown in Figure 1 C.

[0023] A metal conductor 125 (e.g. a layer, such as a thickness, of a conductive metal material), such as tantalum or a stack including tantalum, platinum over the tantalum, and tantalum over the platinum, etc., is formed over dielectric 120 in the example of Figure 1 C. For example, metal conductor 125 is formed over the portion of dielectric 120 that is formed over resistors 1 10-1 to 1 10-3 and the other portion of dielectric 120 that is formed over the inclined surfaces 1 16 of dielectric 104 in the region between successively adjacent resistors 1 10-1 and 1 10-2 and in the region between successively adjacent resistors 1 10-2 and 1 10-3. In some examples, metal conductor 125 is formed in direct physical contact with the surface, e.g., the upper surface, of dielectric 120. In some examples, metal conductor 125 includes inclined segments 130 that are over (e.g., directly over) and in direct physical contact with the inclined surfaces of 124 of the inclined portions 122 of dielectric 120. In some examples, dielectric 120 may act to electrically isolate resistive materials, such as resistive material 109, and other conductors (not shown) from metal conductor 125.

[0024] Portions of metal conductor 125 are removed from the structure of Figure 1 C, as shown in the example of Figure 1 D. For example, the inclined segments 130 of conductor 125 are removed from the inclined surfaces 124 of the inclined portions 122 of dielectric 120 in the regions 1 12 between the resistors 1 10 and the stacks 1 14 to expose the inclined surfaces 124 of the inclined portions 122 of dielectric 120 in the regions 1 12, as shown in Figure 1 D. That is, for example, the inclined segments 130 are removed from the inclined portions 122 (e.g., the inclined surfaces 124 of the inclined portions 122) of dielectric 120 that are in the region between

successively adjacent resistors 1 10-1 and 1 10-2 and that are in the region between successively adjacent resistors 1 10-2 and 1 10-3. Note that the removal of the inclined segments 130 does not act to electrically isolate conductor 125.

[0025] In some examples, metal conductor 125 may be patterned and exposed portions of metal conductor 125 are removed, e.g., stopping on dielectric 120. For example, a mask (not shown), e.g., imaging resist, such as photoresist, may be formed over metal conductor 125 and patterned to define the portions of metal conductor 125 for removal. The portions of metal conductor 125 defined for removal are subsequently removed, e.g., by etching, such as dry etching or wet etching, leaving the remaining portions metal conductor 125 over resistors 1 10-1 to 1 10-3 and, in the example of Figure 1 D, over stacks 1 14.

[0026] The portions of metal conductor 125 that respectively remain over resistors 1 10-1 to 1 10-3 might be referred to as cavitation plates 135, for example. Cavitation plates 135, and thus the portions metal conductor 125 that respectively remain over resistors 1 10-1 to 1 10-3, act to resist the forces generated due to the repeated collapse of the vapor bubbles that are generated in the ink when the ink is heated by the resistors. The vapor bubbles act to eject ink that is above the bubbles from the print head. [0027] In some examples, such as the example of Figure 2A, the metal conductor 125 is also removed from a portion of dielectric 120 that is over the stacks 1 14 while the inclined segments 130 of conductor 125 are removed from the inclined surfaces 124 of dielectric 120. That is, in the example of Figure 2A, the inclined segments 130 of conductor 125, as in Figure 1 C, are removed from the inclined surfaces 124 of dielectric 120 and from the portion of dielectric 120 that is over the stacks 1 14.

[0028] A photoimageable material (e.g., a dielectric) 140 (e.g. a layer, such as a thickness, of photoimageable material 140), such as SU-8 photoresist, is formed over the structure of Figure 1 D, as shown in the example of Figure 1 E. For example, photoimageable material 140 might be formed using a spin-on process, such as a vacuum spin-coating process, or a dry-film lamination process.

[0029] A mask 142 is formed over photoimageable material 140 so that regions over (e.g., directly over) resistors 1 10-1 to 1 10-3 are covered by mask 142.

Electromagnetic radiation 145, such as ultraviolet radiation (e.g., having a

wavelength of about 365 nanometers), is directed onto photoimageable material 140 and mask 142 to expose the regions of photoimageable material 140 uncovered by mask 142 to radiation 145 while leaving the regions of photoimageable material 140 covered by mask 142 unexposed by radiation 145.

[0030] Radiation 145 causes the regions of photoimageable material 140 that are exposed to radiation 145 to crosslink, while the regions of photoimageable material 140 that are unexposed are left uncrosslinked. For example, the term "unexposed" may be taken to include levels of exposure that produce levels of crosslinking that when present in a photoimageable material would allow removal of that

photoimageable material by a solvent, e.g., a developer, such as ethyl lactate. The term "uncrosslinked" may be taken include levels of crosslinking that when present in a photoimageable material would allow removal of that photoimageable material by the solvent.

[0031 ] In some examples, an optical absorber (e.g., sometimes referred to as dye) might be added to photoimageable material 140. For example, the optical absorber may act to increase the amount of radiation 145 absorbed by the photoimageable material 140. [0032] After radiation 145 is applied to the structure of Figure 1 E, the resulting structure, including the crosslinked and unrosslnked regions, is exposed to the solvent. The solvent forms openings150 in the uncrosslinked regions by removing the uncrosslinked regions while leaving portions 152 of crosslinked photoimageable material 140, as shown in the example of Figure 1 F.

[0033] Openings 150 expose portions of conductor 125 that are over and in direct physical contact with the portions of dielectric 120 that are over and in direct physical contact with resistors 1 10-1 to 1 10-3. In some examples, the portions 152 of crosslinked photoimageable material 140 might be referred to as primer portions.

[0034] It should be noted that the removal of inclined segments 130 of metal conductor 125 in Figure 1 D from the inclined surfaces 124 of dielectric 120 prevents reflections of the radiation 145 from the surfaces of inclined segments 130 that occur when the inclined segments 130 are not removed from the inclined surfaces 124 of dielectric 120. The inclined segments 130 can reflect a relatively large portion of radiation 145 received thereat to the regions of photoimageable material 140 that are covered by mask 142 that can lead to the formation of crosslinked photoimageable material 140 in the regions covered by mask 142 that might not be removable by the solvent.

[0035] The formation of crosslinked photoimageable material 140 in the regions covered by mask 142 can at least limit the size of and/or could potentially prevent the formation of openings 150. For example, the formation of crosslinked

photoimageable material 140 in the regions covered by mask 142 might result in the formation of excess crosslinked photoimageable material 140 on the sidewalls of the portions 152 or might form a layer of the crosslinked photoimageable material 140 over the portions of conductor 125 that are over and in direct physical contact with the portions of dielectric 120 that are over and in direct physical contact with resistors 1 10-1 to 1 10-3.

[0036] However, when the inclined segments 130 are removed, the remaining inclined surfaces 124 of dielectric 120 can at least limit the amount of radiation 145 that is reflected to the regions of photoimageable material 140 that are covered by mask 142, relative to the amount of radiation 145 reflected by inclined segments 130, to a level that at least limits the amount of crosslinking to a level where the crosslinked photoimageable material 140 formed under mask 142 does not present a significant impediment to forming openings 150. For example, the region under mask 142 might be substantially free of any crosslinked photoimageable material 140 that cannot be removed by the solvent.

[0037] In examples where dielectric 120 is a combination of silicon carbide and silicon nitride and dielectric 104 is TEOS and where conductor 125 is tantalum, the reflectivity the inclined portion 122 of dielectric 120 over dielectric 104 is about 60 percent less than the reflectivity of inclined segments 130 of metal conductor 125, e.g., for radiation wavelengths of 365 nanometers, plus or minus 10 nanometers.

[0038] A photoimageable material (e.g., a dielectric) 160 (e.g. a layer, such as a thickness, of photoimageable material 160), such as SU-8 photoresist, is formed over the structure of Figure 1 F, filling the openings 150, as shown in the example of Figure 1 G. For example, photoimageable material 160 might be formed using a spin-on process, such as a vacuum spin-coating process, or a dry-film lamination process.

[0039] A mask 162 is formed over photoimageable material 160 so that regions over (e.g., directly over) resistors 1 10-1 to 1 10-3 are covered by mask 162.

Radiation 145 is directed onto photoimageable material 160 and mask 162 to expose the regions of photoimageable material 160 uncovered by mask 162 to radiation 145 while leaving the regions of photoimageable material 160 covered by mask 162 unexposed by radiation 145. Radiation 145 causes the regions of photoimageable material 160 that are exposed to radiation 145 to crosslink, while the regions of photoimageable material 160 that are unexposed are left uncrosslinked.

[0040] After radiation 145 is applied to the structure of Figure 1 G, the resulting structure, including the crosslinked and unrosslnked regions, is exposed to the solvent. As shown in the example of Figure 1 H, the solvent reopens openings 150 and forms openings 164 that are over and contiguous with openings 150 in the uncrosslinked regions by removing the uncrosslinked regions, while leaving the portions 168 of crosslinked photoimageable material 160 over the portions 152 of crosslinked photoimageable material 140.

[0041 ] Contiguous openings 150 and 164 form single continuous openings 165 that expose portions of conductor 125 that are over and in direct physical contact with the portions of dielectric 120 that are over and in direct physical contact with resistors 1 10-1 to 1 10-3. In some examples, the portions 168 might be referred to as chamber portions.

[0042] The removal of inclined segments 130 of metal conductor 125 from the inclined surfaces 124 of dielectric 120 in Figure 1 D prevents reflections of the radiation 145 from the surfaces of inclined segments 130 that occur when the inclined segments 130 are not removed to the regions of photoimageable material 160 that are covered by mask 162. These reflections can lead to the formation of crosslinked photoimageable material 160 in the regions covered by mask 162 that might not be removable by the solvent.

[0043] The formation of crosslinked photoimageable material 160 in the regions covered by mask 162 can at least limit the size of and/or could potentially prevent the formation of openings 164. For example, the formation of crosslinked

photoimageable material 160 in the regions covered by mask 162 might result in the formation of excess crosslinked photoimageable material 160 on the sidewalls of the portions 168, or might form a layer across openings 164 or might form a layer of the crosslinked photoimageable material 160 over the portions of conductor 125 that are over and in direct physical contact with the portions of dielectric 120 that are over and in direct physical contact with resistors 1 10-1 to 1 10-3.

[0044] However, when inclined segments 130 are removed, the remaining inclined surfaces 124 of dielectric 120 can at least limit the amount of radiation 145 that is reflected to the regions of photoimageable material 160 that are covered by mask 162, relative to the amount of radiation 145 reflected by inclined segments 130, to a level that at least limits the amount of crosslinking to a level where the crosslinked photoimageable material 160 formed under mask 162 does not present a significant impediment to forming openings 150 and 164. For example, the region under mask 162 might be substantially free of any crosslinked photoimageable material 160.

[0045] A sacrificial material 170, such as wax, is formed in openings 165 of Figure 1 H, as shown in the example of Figure 1 1. For example, sacrificial 170 might overfill openings 165 and extend over upper surfaces of the portions 168 of crosslinked photoimageable material 160. The sacrificial material 170 is then removed from the upper surfaces of the portions 168, e.g., by chemical mechanical planarization (CMP), so that the upper surfaces of sacrificial material 170 are flush with the upper surfaces of the portions 168, as shown in Figure 1 1.

[0046] A photoimageable material (e.g., a dielectric) 175 (e.g. a layer, such as a thickness, of photoimageable material 175), such as SU-8 photoresist, is formed over the upper surfaces of portions 168 and the upper surfaces of sacrificial material 170, as shown in Figure 1 1. For example, photoimageable material 175 might be formed using a spin-on process, such as a vacuum spin-coating process, or a dry- film lamination process.

[0047] A mask 178 is formed over photoimageable material 175 so that regions over resistors 1 10-1 to 1 10-3 are covered by mask 178. Radiation 145 is directed onto photoimageable material 175 and mask 178. Radiation 145 causes the regions of photoimageable material 175 that are exposed to radiation 145 to crosslink, while the regions of photoimageable material 175 that are unexposed are left

uncrosslinked.

[0048] After radiation 145 is applied to the structure of Figure 1 1, the resulting structure, including the crosslinked and unrosslnked regions, is exposed to the solvent. As shown in the example of Figure 1 J, the solvent reopens openings 165 by removing sacrificial material 170 and forms openings (e.g., orifices) 180 that are over and contiguous with openings 165 in the uncrosslinked regions by removing the uncrosslinked regions, while leaving a layer (e.g., a thickness) 182 of crosslinked photoimageable material 175 over the portions 168 of crosslinked photoimageable material 160. The layer 182 might be referred to as an orifice layer (e.g., an orifice plate) 182, for example. In some examples, layer 182 might be referred to as a tophat layer. Note that Figure 1 J illustrates a portion of an example of a printhead 190.

[0049] In some examples, openings 165 may be referred to as firing chambers 165. For example, the respective orifices 180 may provide outlets for the respective firing chambers 165.

[0050] In some examples, a portion of the layer 182 of crosslinked

photoimageable material 175 over a portion 168 of crosslinked photoimageable material 160 over a portion 152 of crosslinked photoimageable material 140 forms a stack 192 of photoimageable materials that might be referred to as photoimageable material 192. In other examples, photoimageable material 192 might be referred to as a dielectric 192, such as a stack 192 of dielectrics. The sidewalls 195 of successively adjacent dielectrics 192 form sidewalls 195 of the firing chambers 165 between the successively adjacent dielectrics 192.

[0051 ] An example of a portion of a printhead 200 is shown in the example of Figure 2B. Common numbering is used in Figures 1 J and 2B to illustrate similar (e.g., the same components). Printhead 200, for example, may be formed by forming the portions 152 of crosslinked photoimageable material 140 over the structure of Figure 2A, e.g., as described in conjunction with Figures 1 E and 1 F, by forming the portions 168 of crosslinked photoimageable material 160 over the portions 152, e.g., as described in conjunction with Figures 1 G and 1 H, and by forming the layer 182 of crosslinked photoimageable material 175 over the portions 168, e.g., as described in conjunction with Figures 1 1 and 1 J.

[0052] In some examples, printheads 190 and 200 include resistors 1 10-1 and 1 10-2 over dielectric 104. Dielectric 120 includes first and second portions respectively over resistors 1 10-1 and 1 10-2 and an inclined portion 122 over and in direct physical contact with an inclined surface 1 16 of dielectric 104 in a region between resistors 1 10-1 and 1 10-2 for some examples, as shown in Figures 1 J and 2B. Respective metal conductors 125 are respectively over the first and second portions of the second dielectric, as shown in Figures 1 J and 2B. A dielectric 192 between resistors 1 10-1 and 1 10-2 is in direct physical contact with the inclined portion 122 of dielectric 120. Opposing sidewalls 195 of the dielectric 192 between resistors 1 10-1 and 1 10-2 are respectively sidewalls of the firing chambers 165 respectively over the respective metal conductors 125, as shown in Figures 1 J and 2B.

[0053] In some examples, a metal conductor 102 is over dielectric 104 in the region between resistors 1 10-1 and 1 10-2, and the inclined surface 1 16 of dielectric 104 is between resistor 1 10-1 and the metal conductor 102, as shown in Figures 1 J and 2B.

[0054] In some examples, the inclined portion 122 is a first inclined portion 122 of dielectric 120, and the dielectric 120 has a third portion over the metal conductor 102 and a second inclined portion 122 over and in direct physical contact with an inclined surface 1 16 of dielectric 104 that is between resistor 1 10-2 and metal conductor 102, as shown in Figures 1 J and 2B.

[0055] In some examples, print heads 190 and 200, further include the resistive material 109 between the third portion of dielectric 120 and the metal conductor 102, as shown in Figures 1 J and 2B. For example, resistive material 109 over a metal conductor 102 forms a stack 1 14, as shown in Figures 1 J and 2B.

[0056] In some examples, print head 190 further includes a metal conductor 125 over the third portion of dielectric 120, as shown in Figure 1 J. In the example of printhead 200 in Figure 2B, metal conductor 125 has been removed from the third portion of dielectric 120 that is over the metal conductor 102. That is, for example, the third portion of dielectric 120 that is over metal conductor 102 between resistors 1 10-1 and 1 10-2 is devoid of a metal conductor 125 in Figure 2B.

[0057] In some examples of print head 190, the dielectric 192 between resistors 1 10-1 and 1 10-2 is in direct physical contact with the second inclined portion 122 of dielectric 120 and in direct physical contact with the conductor 125 over the third portion of dielectric 120, as shown in Figure 1 J.

[0058] In some examples, printheads 190 and 200 include a resistor 1 10, such as resistor 1 10-2, over dielectric 104. Resistor 1 10-2 is between a pair of metal conductors 102 that are over dielectric 104. Note that in some examples, the metal conductor 102 is part of a stack 1 14 that includes the resistive material 109 over conductor 102.

[0059] Printheads 190 and 200 include dielectric 120. In some examples, dielectric 120 incudes a first portion over resistor 1 10-2, a second portion over a first one of the pair of metal conductors 102 to the left of resistor 1 10-2, a third portion over a second one of the pair of metal conductors 102 to the right of resistor 1 10-2, a first inclined portion 122 over a first inclined upper surface 1 16 of dielectric 104 in a region (e.g., to the left of resistor 1 10-2) between the first one the pair of metal conductors 102 and the resistor 1 10-2 and a second inclined portion 122 over a second inclined upper surface 1 16 of dielectric 104 in a region (e.g., to the right of resistor 1 10-2) between the second one of the pair of metal conductors 102 and the resistor 1 10-2, as shown in Figures 1 J and 2B. A metal conductor 125 is over the first portion of dielectric 120, for example, as shown in Figures 1 J and 2B.

[0060] In some examples, the second portion of dielectric 120 over the first one of the pair of metal conductors 102 to the left of resistor 1 10-2 is over and in direct physical contact with the resistive material 109 over the first one of the pair of metal conductors 102, and the third portion of dielectric 120 over the second one of the pair of metal conductors 102 to the right of resistor 1 10-2 is over and in direct physical contact with the resistive material 109 over the second one of the pair of metal conductors 102, as shown in Figures 1 J and 2B.

[0061 ] A dielectric 192 on the left of resistor 1 10-2 has a first portion over the second portion of dielectric 120 and a second portion in direct physical contact with the first inclined portion 122 of dielectric 120, as shown in Figures 1 J and 2B, for example. A dielectric 192 on the right of resistor 1 10-2 has a first portion over the third portion of dielectric 120 and a second portion in direct physical contact with the second inclined portion 122 of dielectric 120, as shown in Figures 1 J and 2B, for example. A firing chamber 165 is over metal conductor 125 and is between the dielectric 192 on the left of resistor 1 10-2 and the dielectric 192 on the right of resistor 1 10-2.

[0062] In the example of printhead 200 in Figure 2B, the first portion of the dielectric 192 on the left of resistor 1 10-2 that is over the second portion of dielectric 120 is in direct physical contact with the second portion of dielectric 120, and the first portion of the dielectric 192 on the right of resistor 1 10-2 that is over the third portion of dielectric 120 is in direct physical contact with the third portion of dielectric 120.

[0063] In the example of printhead 190 in Figure 1 J, a metal conductor 125 is over the first one of the pair of metal conductors 102 to the left of resistor 1 10-2 and a metal conductor 125 is over the second one of the pair of metal conductors 102 to the right of resistor 1 10-2. In the example of printhead 190 in Figure 1 J, the second portion of the dielectric 192 on the left of resistor 1 10-2 in direct physical contact with the first inclined portion 122 of dielectric 120 extends between the metal conductor 125 over resistor 1 10-2 and the metal conductor 125 that is over the first one of the pair of metal conductors 102 to the left of resistor 1 10-2, and the second portion of the dielectric 192 on the right of resistor 1 10-2 in direct physical contact with the second inclined portion 122 of dielectric 120 extends between the metal conductor 125 over resistor 1 10-2 and the metal conductor 125 that is over the second one of the pair of metal conductors 102 on the right of resistor 1 10-2.

[0064] Figure 3 is a flowchart of an example of a method 300 of forming a printhead. First and second resistors, such as resistors 1 10-1 and 1 10-2, are formed over a first dielectric, such as dielectric 104, in block 310. In block 320, a first portion of a second dielectric, such as dielectric 120, is formed over the first and second resistors and a second portion of the second dielectric is formed over an exposed inclined surface, such as inclined surface 1 16, of the first dielectric in a region between the first and second resistors. A metal conductor, such as metal conductor 125, is formed over the first and second portions of the second dielectric at block 330. In block 340, an inclined segment, such as inclined segment 130, of the metal conductor is removed from an inclined surface, such as inclined surface 124, of the second portion of the second dielectric to expose the inclined surface of the second portion of the second dielectric.

[0065] In some examples, the second portion of the second dielectric might be in direct physical contact with the inclined surface of the first dielectric, and forming the metal conductor over the second portion of the second dielectric might include forming the inclined segment of the metal conductor in direct physical contact with the inclined surface of the second portion of the second dielectric.

[0066] In some examples, method 300 might further include forming a first portion of a photoimageable material over the first portion of the second dielectric and a second portion of the photoimageable material in the region between the first and second resistors and over the exposed inclined surface of the second portion of the second dielectric, exposing the second portion of the photoimageable material to radiation while covering the first portion of the photoimageable material, and exposing the first and second portions of the photoimageable material to solvent to remove the first portion while leaving the second portion. Removing the inclined segment of the metal conductor acts to prevent reflections of the radiation from a surface of the inclined segment of the metal conductor to the covered first portion of the photoimageable material that occur while the second portion of the

photoimageable material is exposed to the radiation when the inclined segment of the metal conductor is not removed. [0067] In some examples, the metal conductor might be a first metal conductor, and method 300 might further include forming a third portion of the second dielectric over a second metal conductor, such as metal conductor 102, that is in the region between the first and second resistors and forming the first metal conductor over the third portion of the second dielectric. In some examples, method 300 might further include removing the first metal conductor from the third portion of the second dielectric while removing the inclined segment of the metal conductor from the inclined surface of the second portion of the second dielectric.

[0068] Figure 4 is a flowchart of an example of a method 400 of forming a printhead. In block 410, a resistive material, such as resistive material 109, is formed over a first metal conductor, such as metal conductor 102, over a first dielectric, such as dielectric 104, and over the first dielectric in an opening, such as an opening 106, in the first metal conductor. At block 420, a resistor, such as a resistor 1 10, is formed, from the resistive material in the opening, and a stack, such as a stack 1 14, comprising the resistive material over the first metal conductor, is formed while removing a portion of the resistive material and a portion of the first metal conductor to form an inclined surface, such as inclined surface 1 16, of the first dielectric in a region between the resistor and the stack. At block 430, a second dielectric, such as dielectric 120, is formed over the resistor, the inclined surface of the first dielectric, and the stack. A second metal conductor, such as metal conductor 125, is formed over the second dielectric in block 440. In block 450, an inclined segment, such as inclined segment 130, of the second metal conductor is removed from an inclined portion, such as inclined portion 122, of the second dielectric in direct physical contact with the inclined surface of the first dielectric.

[0069] In some examples, method 400 might further include removing the second metal conductor from a portion of the second dielectric that is over and in direct physical contact with the stack.

[0070] Although specific examples have been illustrated and described herein it is manifestly intended that the scope of the claimed subject matter be limited only by the following claims and equivalents thereof.