Patent Application
20090246412
The present invention relates to systems and methods for localized deposition of materials in the manufacture of relatively small scale structures. For example, and not by way of limitation, the systems and methods described and defined herein may be employed in the field of microfluidic devices.
Microfluidic devices may also be commonly referred to as microstructured devices, microchannel devices, microreactors, and the like. Regardless of the particular nomenclature utilized, the microfluidic device is a device in or on which a fluid, optionally including solids, can be held and subjected to processing. The fluid can be moving or static or both in turns, although it is typically moving. The processing may involve analysis of the fluid or solids, if any, reaction, heat exchange, other operations, or combinations of operations. The cross-sectional dimensions of channels or passages in such devices are typically on the order of millimeters or smaller. The small dimensions provide considerable improvement in mass and heat transfer rates over larger scale fluidic devices. Microfluidic devices thus offer many advantages over conventional scale reactors, including significant improvements in energy efficiency, reaction speed, reaction yield, safety, reliability, scalability, etc.
The present inventors have recognized a continuing need for improved systems and methods for manufacturing microfluidic devices and other small scale devices. According to one embodiment of the present invention, a localized deposition system is provided comprising a substrate support, a feed material supply, a feedstock laser source, a substrate laser source, and a deposition control system. The substrate support is configured to support a substrate such that a deposition surface of the substrate is in communication with the feed material supply. The feed material supply is configured to provide feed material for localized deposition at a localized portion on the deposition surface of the substrate. The localized deposition system is configured to provide for relative movement between the deposition surface of the substrate and a position in which the feed material is provided for localized deposition. The feedstock laser source is configured to heat feed material positioned for localized deposition on the deposition surface of the substrate. The substrate laser source is configured to heat a localized portion of the substrate. The deposition control system is programmed to synchronize the relative movement between the deposition surface of the substrate and the localized deposition position of the feed material supply with operation of the feedstock laser source, the substrate laser source, and the feed material supply to execute a deposition operation.
According to another embodiment of the present invention, a method of localized deposition is provided where the feed material supply provides a zero expansion glass or glass ceramic feed material for localized deposition and the substrate comprises a zero expansion glass or glass ceramic. The feedstock laser source is configured to generate a laser beam of sufficient thermal energy to heat a tip region of the glass or glass ceramic feed material to a temperature at which it can be bonded to the deposition surface of the glass or glass ceramic substrate through a thermal wetting process.
According to yet another embodiment of the present invention, a method of localized deposition is provided where the substrate laser source is used to heat a localized portion of the substrate and the substrate laser source is configured to generate a laser beam of sufficient thermal energy to contribute to the thermal wetting process by heating the localized portion of the substrate.
The following detailed description of specific embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Referring initially to
The substrate support 20 is configured to support a substrate 22 such that a deposition surface 24 of the substrate 22 is in communication with the feed material supply 30. The feed material supply 30 is configured to provide feed material 32 for localized deposition at a localized portion 26 on the deposition surface 24 of the substrate 22. The feed material 32 may comprise a rod or fiber of fused silica glass, a fused quartz, a glass ceramic, a titanium silicate glass, or any other conventional or yet to be developed thermally compatible deposition material, and may be fed from a reel or spool 38.
In particular embodiments of the present invention, the feed material 32 comprises a glass or glass ceramic and is selected such that its coefficient of thermal expansion is approximately zero, although the present invention is not limited to the context of zero expansion materials. It may also be preferable to select the feed material 32 such that its coefficient of thermal expansion approximates or matches that of the substrate 22, in which case the substrate would typically comprise a glass or glass ceramic having a coefficient of thermal expansion that is approximately zero.
The localized deposition system 10 is configured to provide for relative movement between the deposition surface 24 of the substrate 22 and a position in which the feed material 32 is provided for localized deposition. For example, in the embodiment illustrated in
The feedstock laser source 40 is configured to heat feed material 32 positioned for localized deposition on the deposition surface 24 of the substrate 22. The feedstock laser source 40 is configured to generate a laser beam 42 of sufficient thermal energy to heat a tip region 34 of the feed material 32 to a temperature at which it can be bonded to the deposition surface 24 of the substrate 22 through a thermal wetting process, i.e., a melting or softening temperature of the feed material 32. To aid in set-up or calibration, the feedstock laser source 40 may be provided with controllable beam steering optics 44, e.g., a dual-axis, gimbal-mounted, heat resistant MEMS mirror.
The substrate laser source 50 is configured such that a backside surface 28 of the substrate 22 is positioned in a field of view of the substrate laser source 50 and is configured to generate a laser beam 52 of sufficient thermal energy to contribute to the thermal wetting process by heating the localized portion 26 of the substrate 22. To aid in set-up or calibration, the substrate laser source 50 may be provided with controllable beam steering optics 54, e.g., a dual-axis, gimbal-mounted, heat resistant MEMS mirror.
In the illustrated embodiment, the substrate laser source 50 is configured such that localized heating of the substrate 22 by the substrate laser source 50 progresses from the backside surface 28 of the substrate 22 to the deposition surface 24 of the substrate 22 through a thickness dimension t of the substrate 22. Under this configuration, and where the substrate 22 is fabricated from materials exhibiting thermal conductivities between approximately 1.0 Wm−1K−1 and approximately 1.4 Wm−1K−1 and having thickness dimensions t less than approximately 4 mm, the substrate laser source 50 can be conveniently configured such that the localized heating of the substrate 22 at the deposition surface 24 will rapidly exceed approximately 1500° C. and can readily reach 2000° C.-2500° C., or higher. Suitable substrate materials include, but are not limited to, fused silica glass, fused quartz, glass ceramics, titanium silicate glass, etc.
The deposition control system, which may comprise a network of dedicated programmable controllers or the single programmable deposition controller 60 in communication with the substrate support 20, the feed material supply 30, the feedstock laser source 40, and the substrate laser source 50, is programmed to synchronize the relative movement between the substrate 22 and the tip region 34 of the feed material supply 30 with operation of the feedstock laser source 40, the substrate laser source 50, and the feed material supply 30 to execute a synchronized deposition operation. More specifically, the deposition control system can be programmed to maintain equilibrium mass flow and uniform deposition. Further, and by way of example, not limitation, the deposition control system can be programmed to establish the relative movement of the substrate 22 and the tip region 34 of the feed material supply 30 at an approximately constant velocity or to synchronize changes in the velocity of the relative movement of the substrate 22 and the tip region 34 with changes in a rate at which the feed material supply 30 provides the feed material 32.
Further, the deposition control system can be programmed to maintain the localized deposition position 26 in approximate alignment with the position at which a beam 52 of the substrate laser source 50 contacts the substrate 22. Alternatively, to accommodate for any delay in the transmission of heat to the deposition surface 24, the deposition control system can be programmed to maintain the localized deposition position 26 in offset alignment with the position at which the beam 52 of the substrate laser source 50 contacts the substrate 22. In which case, the offset alignment could be set such that the position at which the substrate laser beam 52 contacts the substrate 22 leads the localized deposition position 26 during relative movement between the substrate 22 and the tip region 34.
It is noted that terms like “preferably,” “commonly,” and “typically,” if utilized herein, should not be read to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention.
For the purposes of describing and defining the present invention it is noted that the terms “approximately” and “substantially” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “approximately” and “substantially” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
It is noted that recitations herein of a component of the present invention being “programmed” in a particular way, “configured” or “programmed” to embody a particular property, or function in a particular manner, are structural recitations as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “programmed” or “configured” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.
Having described the invention in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention.
