Inkjet printing process

Abstract

An inkjet-printing-base process for depositing functional materials, for example PZT, on a substrate, in various instances platinized silicon. Substrate templating (via SAMs) and material deposition are both performed by an inkjet printing process. Additionally, a composition to be used as a SAM precursor ink which is a thiol in a solvent mixture, wherein the composition can be 1 dodecanethiol in a solvent mixture of 2-methoxyethanol and glycerol.

Claims

1. An Inkjet printing process of printing a functional material on a substrate, said process comprising: (a) depositing a self-assembled monolayer (SAM) template having a particular pattern on the substrate via inkjet printing, wherein the inkjet-printed SAM template pattern defines boundaries for the deposition of a functional material; and (b) depositing the functional material within the boundaries of the inkjet-printed SAM template pattern, the functional material being a composition containing PZT (Pb(Zr,Ti)O.sub.3), PLZT ((Pb,La)(Zr,Ti)O.sub.3), PbTiO.sub.3, PbZrO.sub.3, Pb(Mg,Nb,Ti)O.sub.3, BaTiO.sub.3, or (Ba,Ca)(Ti,Zr)O.sub.3 in a solvent consisting in 2-methoxyethanol, glycerol and ethylene glycol.

2. The printing process according to claim 1, wherein depositing a SAM template via inkjet printing comprises inkjet printing a SAM ink that is a composition made of a thiol in a solvent mixture of alcohols and ethers, and the substrate is made of a high surface energy material containing at least a noble metal of the group Pt, Au, Cu, Ir, Pd, Ru.

3. The printing process according to claim 2, wherein the thiol is 1-dodecanethiol and the solvent mixture of alcohols and ethers is 2-methoxyethanol and glycerol.

4. The printing process according to claim 3, wherein the solvent mixture of alcohols and ethers is made of 60 to 90 vol % of 2-methoxyethanol, and the remaining vol % is glycerol.

5. The printing process according to claim 4, wherein the vol % of 2-methoxyethanol is about 75%.

6. The printing process according to claim 3, wherein the quantity of thiol in the solvent mixture of alcohols and ethers is of 0.1 to 0.00001 M.

7. The printing process according to claim 6, wherein the quantity of thiol in the solvent mixture of alcohols and ethers is of about 0.001 M.

8. The printing process according to claim 1, wherein the composition containing PZT consists in PZT diluted to 0.2 M in the solvent, which is made of 65 (±5) vol % 2-methoxyethanol, 25 (±5) vol % glycerol and 10 (±5) vol % ethylene glycol.

9. The printing process according to claim 1, further comprising the following steps, in that order: (c) drying; (d) pyrolysis; (e) crystallization.

10. The printing process according to claim 9, wherein the steps (a) to (d) are repeated one time or more, thus defining a cycle, and step (e) is performed after step (d) every n cycle, n being equal or greater than 1, such that a multi-layer functional material is printed on the substrate.

11. The printing process of claim 1 further comprising utilizing the process to make a microsystem.

Description

DRAWINGS

(1) FIG. 1 is a cross section of a substrate, in accordance with various embodiments of the present invention.

(2) FIG. 2 is a diagram summarizing the preparation of a functional material, in accordance with various embodiments of the present invention.

(3) FIG. 3 illustrates an exemplary embodiment of the printing method, in accordance with various embodiments of the present invention.

(4) FIG. 4 illustrates top view pictures of the printed pattern of films, in accordance with various embodiments of the present invention.

(5) FIG. 5 shows the thickness of the deposition, in accordance with various embodiments of the present invention.

(6) FIG. 6 shows the results of a SIMS analysis, in accordance with various embodiments of the present invention.

DETAILED DESCRIPTION

(7) FIG. 1 shows a cross section (not to scale) of a substrate that can be used for the printing process of the invention. In various embodiments, the substrate can comprise a silicon base with a platinum coating.

(8) FIG. 2 details the process employed to obtain a functional material. In this example, PZT ink is obtained after reflux and dilution.

(9) A mixture of dehydrated lead(II) acetate, zirconium(IV) butoxide and titanium(IV) isopropoxide in 2-methoxyethanol with 10% excess lead is heated at reflux during two hours to ensure homogenization and stabilization of alkoxide species via ligand exchange. The resulting PZT sol is then diluted to 0.2 M with ethylene glycol and glycerol to adjust ink viscosity and surface tension for efficient droplet ejection. For instance, the PZT can be diluted in 65 vol % 2-methoxyethanol, 25 vol % glycerol and 10 vol % ethylene glycol.

(10) FIG. 3 shows an example of pattern/template and a particular printing process according to an exemplary embodiment of the invention. A grid-like pattern is printed with SAMs (step (a) of the printing process). In practice, a first series of parallel lines is printed and then a second series of parallel lines perpendicular to the first series is printed. Then the functional material is printed within the boundaries of the grid-like pattern (step (b) of the printing process).

(11) In a particular example, the steps of drying, pyrolysis and crystallization are applied to obtain a final (dry) film on the substrate, as illustrated on the right side of FIG. 3.

(12) In a particular example of a product obtained by the invention, the two-step full-inkjet-printing process has been used to fabricate an array of 500×500 μm.sup.2 PZT squares. The obtained 80 nm-thick structures are crystallized in perovskite phase.

(13) FIG. 4 shows pictures taken with an optical microscope of the films that can be obtained after multi-layer printing process. The printing steps of FIG. 3 are repeated. They are carried out in the same area of the substrate to build one layer at a time. This means that a precise repositioning of the printing head relative to the substrate for each new layer is performed.

(14) FIG. 5 shows the thickness profile of one of the squares. The measurement of the thickness was made after crystallization of each of the successive layers and prior to printing the next layer. We can see regular thickness along the transverse direction of the square. We can also see that the method of the invention allows a precise positioning of the layers one onto each other. Of course, by varying the density of droplets from one layer to another layer, or varying the functional material, a wide variety of heterogenous products can be printed.

(15) FIG. 6 shows the results of the SIMS analysis (imaging mode) of a film realized with the printing method of the invention. An elemental mapping of titanium, oxygen and sulfur was performed in the edge area of a printed PZT square. Sulfur was mostly detected at the edge of the PZT square.

(16) Both the functional material and the SAM precursor inks were liquid and were in contact with each other during the printing process. The sulfur detected in the layer of functional material can only originate from thiols that have diffused into the functional material precursor ink while both were in liquid state. Such diffused sulfur is not observed when SAMs are deposited by any other method because in these known methods, the liquid functional material ink is only printed once the SAM is formed and there is no residual liquid on the substrate.

(17) Although the printing process, the composition of the SAM, the composition of the functional material, the substrate material and the cartridges have been described in details in separate paragraphs of the description, it has to be noted that each particular embodiment of one of these elements is combinable with each particular embodiment of another one of these elements.