Micro device and manufacturing method thereof

A micro device and manufacturing method thereof. The micro device includes a substrate, an insulation layer, and a solution. The insulation layer is disposed on the substrate to define a channel portion and an extension portion communicated with the channel portion. The solution is location in the channel portion. Part of the solution flows to the extension portion by capillary force between the channel portion and the extension portion.

BACKGROUND

The invention relates to micro devices, and in particular, for micro devices having a solution process that needs a uniform thickness therein due to capillary force.

Inkjet dispensing technique may be used to manufacture said micro devices, such as color filters, organic electroluminescent displays (OELD), micro lens, printed circuit board, and detection chips. During manufacture, a pattern with trench structure is pre-defined on a substrate to form a pixel element. The trenches are purposed to induce a uniform film generated on the substrate by ink-jet dispensing. Since ink-jet dispensing is unstable in the early stage and may deteriorate the substrate. Typically, the dispensing behavior becomes more stable after early stage, about several hundred drops ejected. Experience shows that the early-instable and following-stable behavior will cause the pressure difference which is generated due to capillary force along with the printing direction. It makes the thickness of the film may be non-uniform along the printing direction. Furthermore, if the trench is closed structure, the defect near ends of the pixel becomes serious since the pressure difference was balance by the close end, and form white omission at both ends of trench.

US Pat. No. 2003/0193057 discloses an organic light emitting diode and method for producing the same. Referring toFIGS. 1a-1c, to manufacture the organic light emitting diode, an electrode layer2is first formed on a substrate1. A first insulation layer3and a second insulation layer4are then formed on the electrode layer2. Finally, barriers8are formed at both ends41and42of a channel40formed by the second insulation layer4. The thickness difference of organic polymer layers5and6filled in the channel40may be reduced by the barriers8. Nevertheless, the insulation layers are formed by two steps, and the barriers are formed in the channel, thus complicating the process.

SUMMARY

An open trench structure of micro devices are provided. An exemplary embodiment of a micro device comprises a substrate, an insulation layer, and a solution. The insulation layer is processed on the substrate to define a channel portion and an extension portion communicated with the channel portion. The solution is located in the channel portion. Part of the solution flows to the extension portion by capillary force between the channel portion and the extension portion.

Furthermore, the channel portion comprises a uniform width (r). The extension portion is convergent with respect to the channel portion, and comprises a minimum width (a1), wherein 0<a1/r≦1. Alternatively, the extension portion may be divergent with respect to the channel portion, and comprises a maximum width (a2), wherein 1≦a2/r<100.

Moreover, the channel portion comprises a first end communicating with the extension portion, and a second end, opposite to the first end, communicating with the extension portion.

Additionally, the micro device further comprises an electrode layer located between the substrate and the insulation layer. The solution is located on the electrode layer. The electrode layer comprises indium tin oxide.

Note that the extension portion comprises a plurality of stepped portions. The substrate comprises can be glass or flexible substrate likes polyimide but not limited. Furthermore, the thickness of the channel portion can be fabricated in non-uniform structure along with trench to induce the flowing, and the cross section of the channel portion may be a quadrangle, a trapezoid, an inverted trapezoid, a parabola, a triangle, an inverted triangle, or a T-shape.

A method for manufacturing a micro device is also provided. An exemplary embodiment of a method for manufacturing a micro device comprises the following steps. A substrate and a solution-generating device are provided. A patterned insulation layer is formed on the substrate to define a channel portion and an extension portion communicated with the channel portion. A solution is provided in the channel portion via the solution-generating device, wherein part of the solution flows to the extension portion by capillary force between the channel portion and the extension portion.

Furthermore, the method comprises the following steps. Before the insulation layer is formed on the substrate, the substrate surface has been processed by plasma treatment or self-assembled monolayer treatment, and an electrode layer has formed on the substrate. After part of the solution was discharged and then flows to the extension portion from the channel portion, the solution is gradually drying in the channel portion and the extension portion, then elongates the film and smoothes the film surface.

Note that the solution-generating device may be an inkjet head or a dispensing machine. The solution comprises micro particles.

DETAILED DESCRIPTION

Referring toFIG. 2a, an embodiment of a micro device100comprises a substrate110, an electrode layer120, an insulation layer130, and a solution140. The substrate110may be made of glass or flexible substrate likes polyimide but not limited, and used as a base of the micro device100.

The electrode layer120is disposed on the substrate110to be located between the substrate110and the insulation layer130. The electrode layer120may be made of indium tin oxide, and used as an electrode of the micro device100.

The insulation layer130is disposed on the electrode layer120of the substrate100to define a channel portion131and an extension portion132. As shown inFIG. 2b, the solution140is received in the channel portion131. The extension portion132communicates with the channel portion131, and comprises a plurality of stepped portions132′. By means of width differential between the channel portion131and the extension portion132, part of the solution140in the channel portion131flows to the extension portion132by capillary force between the channel portion131and the extension portion132. Thus, the thickness of the solution140in the channel portion131may be uniform, and defects may not be generated at ends of the channel portion131.

Specifically, inFIG. 2b, the channel portion131comprises a uniform width (r). The extension portion132is convergent with respect to the channel portion131, and comprises a minimum width (a1), wherein 0<a1/r<1. A balance equation of the capillary theorem is 2γp/Rp=2γd/Rd−2γpdcos (θa)/r. If θaand γ are constant respectively, part of the solution140in the channel portion131may flow to the extension portion132by controlling the width of the channel portion131and the extension portion132.

Additionally, in practice, the insulation layer130comprises a plurality of channel portions therein; however, only one channel portion is shown inFIG. 2bfor simplicity.

Furthermore, note that the profile of the extension portion132is not limited to the profile shown inFIG. 2b. For example, another embodiment of an insulation layer130ashown inFIG. 3acomprises an extension portion132awithout stepped portions. Another embodiment of an insulation layer130bshown inFIG. 3bcomprises a channel portion131band an extension portion132b. The extension portion132bis divergent with respect to the channel portion131b, and comprises a maximum width (a2), wherein 1<a2/r<100. Another embodiment of an insulation layer130cshown inFIG. 3ccomprises a channel portion131cand an extension portion132c. The width of the extension portion132cis the same as that of the channel portion131c; that is, the ratio there between is one.

Moreover, while the extension portion132is simply communicated with one end of the channel portion131inFIG. 2b, it is not limited thereto. For example, another embodiment of an insulation layer130dcomprises a channel portion131dand two extension portions132dcommunicated with both ends of the channel portion131drespectively.

A cross section profile of the channel portion may be a quadrangle, a trapezoid, an inverted trapezoid, a parabola, a triangle, an inverted triangle, or a T-shape. The thickness of the channel portion may be uniform, or may be fabricated in non-uniform structure along with trench to induce the flowing.

An embodiment of a method for manufacturing the micro device100comprises the following steps. Referring toFIG. 2a, a substrate110is placed on a base200. The surface of the substrate110is processed by plasma treatment or self assembly monolayer treatment to obtain the required hydrophilic/hydrophobic property. Then, an electrode layer120is formed on the substrate110. A patterned insulation layer130is formed on the electrode layer120to define a channel portion131and an extension portion132. A solution140is provided in the channel portion131via a solution-generating device132to contact the electrode layer120. Part of the solution140flows to the extension portion132by capillary force between the channel portion131and the extension portion132. The solution140is dried in the channel portion131and the extension portion132. The extension portion132is separated from the channel portion131to obtain a required micro device.

Note that the solution-generating device300may be an inkjet head or a dispensing machine. The solution140may comprise micro particles. Additionally, the surface treatment may only be performed on the area for forming the channel portion.

In summary, when the solution is located in the channel portion on the substrate, part of the solution may flow to the extension portion, thus balancing the pressure difference. After the solution is completely dried, a film with uniform thickness may be obtained.