PARYLENE CAPPING LAYER FOR EMBEDDED LIQUID PACKAGING

Abstract

A variety of applications can include parylene capping layer for embedded liquid packaging. A capping structure for liquid packaging can include a conformal parylene capping layer on and contacting a liquid in a recessed cavity of a substrate such that the parylene prevents the liquid from leaking out of the cavity, embedding the liquid in the cavity of the substrate. The selections of substrate, liquid, or type of parylene can be based on the application for which the liquid packaging is implemented.

Claims

1. A method comprising: forming a cavity or recessed surface in a substrate; filling the cavity or recessed surface with a liquid; and conformally forming parylene on and contacting the liquid such that the parylene prevents the liquid from leaking out of the cavity or recessed surface, embedding the liquid in the cavity or recessed surface of the substrate.

2. The method of claim 1, wherein the method includes conformally forming the parylene in a vacuum.

3. The method of claim 2, wherein the vacuum has a pressure between 25 mTorr and 100 mTorr.

4. The method of claim 1, wherein conformally forming parylene on and contacting the liquid includes conformally forming parylene on and contacting combination of the substrate and the liquid in the cavity or recessed surface of the substrate.

5. The method of claim 1, wherein the liquid is static in the cavity or the recessed surface.

6. The method of claim 1, wherein the liquid flows in the cavity or the recessed surface.

7. The method of claim 1, wherein filling the cavity or the recessed surface includes only partially filing the cavity or the recessed surface.

8. The method of claim 1, wherein the substrate is a silicon substrate.

9. The method of claim 1, wherein the substrate is a biocompatible substrate.

10. The method of claim 9, wherein the method includes forming the substrate as part of a device that is implantable in a human.

11. The method of claim 1, wherein the liquid is a silicone oil, a liquid metal, a coolant liquid, or a biological liquid.

12. The method of claim 1, wherein the liquid has a composition that does not alter under conditions for conformally forming the parylene on the liquid in the cavity.

13. The method of claim 1, wherein forming the cavity or recessed surface in the substrate includes drilling the substrate, wet or dry etching the substrate, laser etching the substrate, or three-dimensional printing of the cavity or the recessed surface in the substrate.

14. The method of claim 1, wherein the parylene is parylene-C.

15. The method of claim 1, wherein the parylene is a high temperature parylene.

16. An article of manufacture comprising: a substrate; a liquid in a cavity or recessed surface of the substrate; and a conformal parylene capping layer on and contacting the liquid such that the parylene prevents the liquid from leaking out of the cavity or recessed surface, embedding the liquid in the cavity or recessed surface of the substrate.

17. The article of manufacture of claim 16, wherein the substrate is a biocompatible substrate.

18. The article of manufacture of claim 16, wherein the liquid is a silicone oil, a liquid metal, a coolant, or a biological liquid.

19. The article of manufacture of claim 16, wherein the conformal parylene is conformal encapsulating combination of the substrate and the liquid in the cavity or recessed surface of the substrate.

20. The article of manufacture of claim 16, wherein the liquid is static in the cavity or recessed surface.

21. The article of manufacture of claim 16, wherein the article of manufacture includes a channel to flow the liquid in the cavity or recessed surface.

22. A method comprising: forming a cavity or recessed surface in a substrate by a material removal process, by a material additive process, or combination of material removal process and material additive process, the cavity or recessed surface having a top level; filling the cavity or recessed surface with a liquid to a level below the top level, the liquid being a composition that maintains its structural format under processing conditions for capping the liquid in the cavity; and capping the liquid in the substrate by conformally depositing parylene on and contacting the liquid such that the parylene prevents the liquid from leaking out of the cavity, embedding the liquid in the cavity of the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Embodiments of the invention are illustrated by way of example and not limitation in the figures of the accompanying drawings in which:

[0005] FIGS. 1A-1C are a representation of an example process flow of generating a parylene capping or encapsulation layer to embed a liquid in a structure, in accordance with various embodiments.

[0006] FIG. 2 is an image of a structure for mechanical resonant frequency testing showing accelerometer, cantilever, and 22 cavity test structure with silicone oil and parylene capping layer, in accordance with various embodiments.

[0007] FIGS. 3A-3D show images illustrating parylene-C capping layer capability on various liquids and viscosities, in accordance with various embodiments.

[0008] FIG. 4 shows air evaporation results for 20 C. testing illustrating mass changes as a function of time, in accordance with various embodiments.

[0009] FIGS. 5A-5B demonstrate testing results for elevated temperature air evaporation illustrating mass changes as a function of time, in accordance with various embodiments.

[0010] FIGS. 6A-6F show images of the test structures after 80 C. testing, in accordance with various embodiments.

[0011] FIG. 7 shows results of elevated temperature soak testing at 80 C. with mass changes as a function of time, in accordance with various embodiments.

[0012] FIGS. 8A-8C show images of capping layers after an 18-day soak test at 80 C., in accordance with various embodiments.

[0013] FIGS. 9A-9B show results of the mechanical reliability testing at resonant frequency and shock testing, in accordance with various embodiments.

[0014] FIG. 10 is a flow diagram of features of an example method of capping a liquid in a structure, in accordance with various embodiments.

DETAILED DESCRIPTION

[0015] The following detailed description refers to the accompanying drawings that show, by way of illustration and not limitation, various example embodiments of the invention. These embodiments are described in sufficient detail to enable those skilled in the art to practice these and other embodiments. In order to avoid obscuring embodiments of the invention, some well-known system configurations and process steps are not disclosed in detail. Other embodiments may be utilized, and structural, logical, and electrical changes may be made to these embodiments. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The following detailed description is, therefore, not to be taken in a limiting sense.

[0016] Microelectromechanical systems (MEMS) packaging is over 80% of the cost of a typical MEMS device because there are no standard packaging methods, and each device requires unique packaging. Recently, several MEMS devices have illustrated the desire to have a liquid filled cavity within the MEMS device for applications such as biomedical sensors, tunable energy harvesters, or liquid cooling microelectronics. However, embedded liquids in silicon pose a challenge when it comes to packaging.

[0017] In various embodiments, a conformal parylene coating is used to cap or encapsulate a liquid. This approach is validated using various liquids such as various viscosity silicone oils as well as Galinstan, which is a Ga-based liquid metal. This disclosure investigated the packaging reliability through a series of systematic accelerated life-time testing, elevated temperature testing, accelerated soak testing, and mechanical testing including shock and resonant frequency testing. Mass changes were monitored and compared to control (no capping), glass epoxy bond packaging, and silicone spray coating encapsulation. The results demonstrate the superior mean-time-to-failure of the parylene capping method compared to the other methods. The results confirm that parylene can be used to package embedded liquids in silicon, three-dimension (3D) printed structures, or other substrate structures.

[0018] MEMS packaging along with microelectronics packaging is a critical component to the performance of the device, and for MEMS packaging there are no standard packaging techniques as each device has specific packaging needs. Some MEMS and microelectronics devices could benefit from the potential to embed liquid inside of the device, but to date this concept has been limited by the high packaging challenges associated with embedded liquids. Applications including microfluidics such as lab on chip, microelectronic cooling using flowing liquids, microthrusters, and atomizers all require a packaging method that allows liquid to be embedded in micro-channels without leakage. Recently energy harvesters have also demonstrated advantages when integrating embedded liquids to increase bandwidth or tuning resonant frequencies. However, so far these types of devices are limited to research labs as packaging embedded liquids is challenging as leakage can lead to catastrophic failure for the device and its electronics. These applications could be used for anything from implants to consumer electronics. Therefore, the packaging needs to be able to withstand leak testing but also it must be able to withstand vibrations (especially for kinetic energy harvesters).

[0019] Typically, packaging for these types of devices includes glass bonding or silicone encapsulation packaging but these are not ideal as they often require thick layers adding to the mass of the system, which for energy harvesters can significantly alter the resonant frequency and affect performance.

[0020] Parylene is a conformal chemical vapor deposited polymer that is deposited at room temperature. It has numerous advantages over other polymers such as: pinhole free, low water absorption, relatively good thermal properties (dependent on type of parylene), thickness range from 200 nm-50 m, transparency, and other advantages. It has also been widely used previously in MEMS packaging as well as encapsulation layers. It has also been used previously as a capping layer for embedded nanomagnets in silicon. Recent efforts have demonstrated its potential use in packaging implantable pressure sensors covered in high viscosity silicone oil.

[0021] In various embodiments, a thin-film parylene-based capping layer can be implemented for embedded liquids. The parylene-based capping layer can be applied to various liquids from silicone oil with varying viscosities to gallium-based liquid metals and other appropriate liquids. This disclosure provides an investigation of the effects of concavity and filling ratios. The study within this disclosure also investigates the reliability of the packaging by putting various test devices under various accelerated air evaporation testing, soak testing, as well as mechanical vibration testing. This disclosure provides teachings regarding embedding liquids into a cavity or other trench-like structure in a substrate and capping the entire cavity or other trench-like structure in a substrate in parylene to prevent liquid leakage. The cavity or other trench-like structure in a substrate can be, but is not limited to, a silicon cavity or other trench-like silicon structure. A unfilled cavity in a structure is an unfilled volume in the structure, for example, a hollowed-out space in the structure having a bottom and sidewalls.

[0022] FIGS. 1A-1C are a representation of an embodiment of an example process flow of generating a parylene capping layer to embed a liquid in a structure. FIG. 1A shows a cross-sectional view of an embodiment of an example structure 100A after a structure has been processed to remove material. A cavity 113 has been formed in a substrate 105 that is to be used to contain a liquid. The cavity can be formed using an etchant in an etching process that is appropriate for the structure being etched. Substrate 105 can be, but is not limited to, a silicon substrate.

[0023] FIG. 1B shows a cross-sectional view of a structure 100B that has been formed after processing structure 100A of FIG. 1A. Cavity 113 has been filled with a liquid 100. Liquid 110 can be filled to a level below the top of cavity 113. Liquid 110 can be selected for a particular application for an embedded liquid and for its properties that meet fabrication specifications. For a liquid embedding and encapsulation process performed in vacuum, the liquid selected should be a composition that does not significantly alter its format in the vacuum conditions used. For example, the liquid should not bubble over before encapsulation.

[0024] FIG. 1C shows a cross-sectional view of a structure 100C that has been formed after processing structure 100B of FIG. 1B. A conformal parylene coating 115 has been formed on liquid 110 and substrate 105. Conformal parylene coating can be structured to completely encapsulate the combination of liquid 110 embedded in substrate 105. Alternatively, conformal parylene coating 110 can be generated to cap liquid 110 to maintain liquid 110 in cavity 113 of substrate 105.

[0025] In testing, silicon wafers were used to create test structures, but 3D printed structures could also have been used. An oxide was grown on the wafers and patterned to have 220.05 cm square cavities. The cavities were created using deep reactive ion etching (DRIE) using parameters described in P. Sharma, M. Pleil, and N. Jackson, Effect of SF6 and C4F8 Flow Rate on Etched Surface Profile and Grass Formation in Deep Reactive Ion Etching Process, in ASME International Mechanical Engineering Congress and Exposition, 2022, vol. 86717: American Society of Mechanical Engineers, p. V009T13A012, incorporated herein by reference in its entirety. The cavities were similar to cavity 113 of FIG. 1A. Liquid was dispensed into the cavity. Various liquids were investigated, consisting of four different viscosities of silicone oil (100, 1 k, 10 k, and 100 k cST). Viscosity is commonly defined in units of centistoke (cST) for kinematic viscosity and centipoise (cP) for dynamic (absolute) viscosity. In addition to silicone oil, Galinstan, which is a Ga-based liquid metal, was also used to illustrate the potential to encapsulate an electrically conducting liquid with large density (>6 g cm.sup.3) and low viscosity (2 cST). Galinstan is a family of eutectic alloys of gallium, indium, and tin, which are liquid at room temperature (RT). The cavities were filled to varying thicknesses ranging from 20-100% fill volume of the cavity. Parylene-C was deposited using the Gorham methods as described in N. Jackson, F. Stam, J. O'Brien, L. Kailas, A. Mathewson, and C. O'Murchu, Crystallinity and mechanical effects from annealing Parylene thin films, Thin Solid Films, vol. 603, pp. 371-376, 2016, incorporated herein by reference in its entirety.

[0026] Parylene-C was selected as it is the most common type of parylene and the deposition rate is higher than other parylenes allowing for thicker layers. Thickness of 20 m was deposited. A silane (A-174) adhesion layer was coated on the substrates. A pressure of 25 mTorr was used to deposit the parylene.

[0027] Control samples consisted of no packaging, only liquid filled cavities. To compare the reliability of the parylene encapsulation two other methods were investigated. The first method used glass slides that were bonded to the liquid filled cavities using a room temperature cured epoxy to bond the glass to the silicon cavity. The other method investigated was the use of silicone encapsulation (Q-ballz Smooth On that is a single component liquid that can be used as a bald cap plastic or for encapsulating silicone gel prosthetic appliances), which was spray coated on the liquid filled cavities in n=5 layers for a total thickness of approximately 100 m.

[0028] Reliability testing included evaporation testing. Air evaporation testing was performed at three different room temperatures of approximately 20 C., 50 C., and 80 C. The elevated temperature of 50 C. was selected as it is approximately the glass transition temperature of Parylene-C. However, since silicone oil has a slow evaporation rate at room temperature, accelerated testing was performed up to 80 C. The evaporation testing was performed in an oven with an air environment.

[0029] Twelve cavities of each liquid were filled in a 43 array, with cavities filled between 20-100%. Variation of filling was used to determine if the parylene capping layer would create a solid capping film on various amounts of filling. Liquids investigated were silicone oil of viscosities of 100, 1,000, 10,000, and 100,000 cST that were filled and coated with parylene as described above. Other test devices consisted of controls, which included no capping layer filled with each type of silicone oil in three cavities. A test structure with a silicone encapsulation, which was spray deposited, and a glass slide epoxy bonded capping layer were also tested. Testing was performed by weighing the test structures and determining any change in weight due to evaporation.

[0030] Accelerated temperature testing was performed to calculate an acceleration factor using the Arrhenius equation:

[00001]$\begin{array}{cc}AF=e^{\left[\frac{\mathrm{Ea}}{k}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)\right]},& \left(1\right)\end{array}$

[0031] where AF is the acceleration factor, k is Boltzman's constant, T.sub.1 and T.sub.2 are the lower and higher temperatures in K, and E.sub.a is the activation energy, which for the evaporation study was 0.7 eV. The AF was used to determine the mean time to failure (MTTF).

[0032] Soak testing was performed by submerging the test structures in water that was heated to 80 C. for accelerated testing. Testing structures consisted of the same type as used in air evaporation testing. However, parylene capping of liquid metal (Galinstan) was also investigated, as this liquid metal has been used in numerous electronic applications since it is liquid at room temperature. Test structures were weighed to determine any change in weight caused from leaking or absorption.

[0033] Mechanical reliability testing was performed by placing a 22 cavity array test structure with silicone oils and various capping methods on the end of a piezoelectric cantilever as shown in FIG. 2. Two different tests were performed using an electrodynamic vibration shaker. The first test consisted of shaking the test structure and cantilever at resonant frequency for 1 day at various accelerations and then measuring their change in mass to determine if there was any leakage. The second test that was performed was a shock test, which consisted of impulse shocks from 0-50 g.

[0034] FIGS. 3A-3D illustrate the ability to create a parylene-C capping layer on various liquids. FIG. 3A shows parylene-C on low viscosity silicone oil of viscosities of 100-1000 cST, which illustrates a smooth parylene layer that is near wrinkle free. FIG. 3A shows capping of convex and concave films for various filling ratios. FIG. 3B illustrates the ability to create a parylene capping film on top of a viscous 100k cST silicone oil. The image shows significant wrinkling due to stress of the film, but a solid parylene film was still created. FIG. 3C illustrates the ability to create a parylene capping layer on liquid metal Galinstan. Even when the liquid metal did not completely fill the cavity the parylene was conformally coated to encapsulate the metal, thus reducing the parylene volume. FIG. 3D shows a silicone spray encapsulation film covering the silicone oil.

[0035] FIG. 4 demonstrates room temperature evaporation testing results. FIG. 4 is a plot of mass change in percentage over duration days for seven cases. Curve 443 is curve for a control of no capping. Curve 442 is for silicone encapsulation. Curve 441 is for a glass capping. Curve 444 is for parylene on silicone oil having a viscosity of 100K cST. Curve 447 is for parylene on silicone oil having a viscosity of 1K cST. Curve 446 is for parylene on silicone oil having a viscosity of 10K cST. Curve 448 is for parylene on silicone oil having a viscosity of 100 cST. The results demonstrate that parylene capping test structures had no significant change in mass over a 50-day testing period indicating there was no significant evaporation of the liquids. Although silicone oil has a low evaporation rate, the control with no capping layer demonstrated significant decrease in mass (>5%) after 16 days, and it continued to decrease over time reaching nearly 13% decrease over the 50 days. The spray on silicone encapsulation film test devices also demonstrated a significant decrease of up to 4.2% over 50 days. The glass packaging films had similar results as the parylene capping method.

[0036] FIGS. 5A-5B show testing results for elevated temperature air evaporation. FIG. 5A is a plot of mass change in percentage for air evaporation at 50 C. over duration days for seven cases. Curve 543A is curve for a control of no capping. Curve 542A is for silicone encapsulation. Curve 541A is for a glass capping. Curve 544A is for parylene on silicone oil having a viscosity of 100K cST. Curve 547A is for parylene on silicone oil having a viscosity of IK cST. Curve 546A is for parylene on silicone oil having a viscosity of 10K cST. Curve 548A is for parylene on silicone oil having a viscosity of 100 cST.

[0037] FIG. 5B is a plot of mass change in percentage for air evaporation at 80 C. over duration days for seven cases. Curve 543B is curve for a control of no capping. Curve 542B is for silicone encapsulation. Curve 541B is for a glass capping. Curve 544B is for parylene on silicone oil having a viscosity of 100K cST. Curve 547A is for parylene on silicone oil having a viscosity of 1K cST. Curve 546A is for parylene on silicone oil having a viscosity of 10K cST. Curve 548A is for parylene on silicone oil having a viscosity of 100 cST.

[0038] The results, demonstrated in FIGS. 5A-5B, show a significant decrease in mass (30% at 80 C. at 18 days and 15% at 50 C. at 30 days). The silicone encapsulation and glass packages also had significant decrease in mass. The glass test structures were bonded with low temperature epoxy which likely melted at high temperatures, which could potentially be resolved by using higher-temperature grade epoxy. However, the parylene-capped test structures showed no significant change in mass. The 100 cST silicone oil did show a 0.9% decrease in mass at 18 days of 80 C., whereas 100 k cST oil only showed 0.5% decrease in mass under the same test. This demonstrates that high viscosity liquids with parylene capping are likely to have a longer lifetime.

[0039] Using the Arrhenius equation and the criteria that a 5% loss is considered failure, the inventor predicts the MTTF to be approximately 51 years at room temperature. More samples and longer testing periods can be used to obtain a more accurate estimation. Images of the testing structures after 80 C. air testing are shown in FIGS. 6A-6F. FIG. 6A is an image of Galinstan with a parylene coating. FIG. 6B is an image of a parylene coating on silicone oil having a viscosity of 1000 cST. FIG. 6C is an image of glass encapsulation with epoxy bond. FIG. 6D is an image of a parylene coating on silicone oil having a viscosity of 10K cST. FIG. 6E is an image of silicone spray encapsulation with epoxy bond. FIG. 6F is an image of a parylene coating on silicone oil having a viscosity of 100K cST. The parylene capped structures look similar to the initial images, but the glass capped packages demonstrate air bubbles indicating leaks in the bonds. The silicone spray encapsulation packaging likely dissolved which led to leakage.

[0040] FIG. 7 shows results of elevated temperature soak testing. FIG. 7 is a plot of mass change in percentage over duration days for eight cases. Curve 743 is curve for a control of no capping. Curve 442 is for silicone encapsulation. Curve 441 is for a glass capping. Curve 444 is for parylene on silicone oil having a viscosity of 100K cST. Curve 447 is for parylene on silicone oil having a viscosity of 1K cST. Curve 446 is for parylene on silicone oil having a viscosity of 10K cST. Curve 448 is for parylene on silicone oil having a viscosity of 100 cST. Curve 449 is for parylene on liquid (LM). The control cavities had catastrophic failures in all of the cavities as expected as there no protection layer to prevent the leakage of the silicone oil. As with the elevated temperature air testing the glass and silicone encapsulation demonstrated significant decrease leading to failures, which is likely due to the heat. The liquid metal with parylene coating had one of the twelve cavities failed at day 9, which shows a significant loss in mass, but afterwards the mass held constant. The cavity that failed had a tear in the parylene that caused the LM to leak out completely but only from one cavity. Most of the parylene-capping test structures demonstrated an increase in mass by up to 21% for 100 cST and 6% for higher viscosity silicone oils. The reason for the increase in mass is likely due to water absorption of the parylene, as the mass increase happened early in the testing and then saturated. However, there was no significant decrease in mass, this means that the parylene capping did not show any signs of silicone oil leakage during the test.

[0041] FIGS. 8A-8C show images of capping layers after an 18-day soak test at 80 C. FIG. 8A shows an image of parylene coating on Galinstan. FIG. 8B shows an image of parylene on silicone oil having a viscosity of 100 cST. FIG. 8C shows an image of parylene on silicone oil having a viscosity of 1000 cST. The images show significant warpage and wrinkles in all the films, which is likely due to the coefficient of thermal expansion mismatch between the parylene (35 ppm/ C.) compared to silicone oil (1%/ C.). However, since parylene-C has an elongation to break of approximately 200%, the film can stretch as illustrated in the images. However, the wrinkles in the parylene-capping layer did not seem to affect its leakage performance in silicone oil and only one cavity failure occurred for liquid metal.

[0042] Mechanical testing results are important to determine if the parylene capping film can withstand vibrations and shocks without delaminating or tearing. FIGS. 9A-9B show results for both tests. FIG. 9A shows mass change in percentage versus acceleration at resonant frequency for five cases. Curve 953A is curve for a control of no capping on silicone oil having a viscosity of 100 cST. Curve 942A is for silicone encapsulation on silicone oil having a viscosity of 100 cST. Curve 951A is for control of no cap on silicone oil having a viscosity of 100K cST. Curve 944A is for parylene on silicone oil having a viscosity of 100K cST. Curve 948A is for parylene on silicone oil having a viscosity of 100 cST. Resonant frequency testing at various accelerations illustrates that the control sample without capping showed a gradual decrease in mass at various accelerations, and above 1.75 gs the silicone oil was completely removed from the cavity, but significant leakage (>5% in mass) was demonstrated at 0.4 g. The viscosity of the liquid does have a significant influence, as the 100 cST silicone oil failed at lower acceleration than the 100k cST (>5% at 1 g). The spray on silicone encapsulation test structures also failed at 1.5 g. However, the parylene-capped structures with 100 and 100k cST silicone oil demonstrated no significant change in mass or resonant frequency up to 2 g. Higher accelerations were not possible as it would have broken the cantilever.

[0043] FIG. 9A shows mass change in percentage versus acceleration for a shock test for one case. Curve 948B is for parylene on silicone oil having a viscosity of 100 cST. Shock testing of the 100 cST silicone oil and parylene-capping film demonstrated no significant leakage with only 0.53% loss in mass at 50 g. Higher acceleration testing was not possible on the system used.

[0044] FIG. 10 is a flow diagram of features of an embodiment of an example method of capping a liquid in a structure. At 1010, a cavity or recessed surface is formed in a substrate. At 1020, the cavity or recessed surface is filled with a liquid. Filling the cavity or recessed surface can include only partially filing the cavity or recessed surface. At 1030, parylene is conformally formed on and contacting the liquid such that the parylene prevents the liquid from leaking out of the cavity or recessed surface, embedding the liquid in the cavity or recessed surface of the substrate.

[0045] Variations of method 1000 or methods similar to method 1000 can include a number of different embodiments that may be combined depending on the application of such methods or the architecture or operation flow for which such methods are implemented. Such methods can include conformally forming the parylene in a vacuum. The vacuum can have a vacuum pressure between 25 mTorr and 100 mTorr. Variations can include conformally forming parylene on and contacting the liquid by conformally forming parylene on, contacting, and encapsulating combination of the substrate and the liquid in the cavity or recessed surface of the substrate.

[0046] Variations of method 1000 or methods similar to method 1000 can include the substrate being a silicon substrate. Variations can include the substrate being a biocompatible substrate. Variations can include processing the substrate as part of a device that is implantable in a human.

[0047] Variations of method 1000 or methods similar to method 1000 can include the liquid being a silicone oil. Variations can include the liquid being a liquid metal. The liquid metal can be Galinstan. The liquid can be a biological liquid or a coolant such as, but not limited to, a microelectronics coolant. The liquid can be static in the cavity or the recessed surface. The liquid can be a flowing liquid in the cavity or recessed surface. Variations can include the flowing liquid being removed from the cavity of the recessed surface. A channel can be implemented to provide entry and exit of the flowing liquid in the cavity or recessed surface. Variations can include the liquid having a composition that does not alter under conditions for conformally forming the parylene on the liquid in the cavity or recessed surface.

[0048] Variations of method 1000 or methods similar to method 1000 can include forming the cavity in the substrate by etching the substrate to form the cavity. The etching can be performed by DRIE, wet etching, or combinations of etching processes. Forming the cavity or recessed surface in the substrate can include drilling the substrate, wet or dry etching the substrate, laser etching the substrate, or three-dimensional printing of the cavity or the recessed surface in the substrate.

[0049] Variations can include the parylene being parylene-C. Variations can include the parylene being a high temperature parylene, which can handle temperatures on a continual basis up to a level above 200 C. Other forms of parylene can be used depending on the application for the liquid packaging.

[0050] Variations of method 1000 or methods similar to method 1000 can include forming a cavity or recessed surface in a substrate by a material removal process, by a material additive process, or combination of material removal process and material additive process, where the cavity or recessed surface has a top level. A cavity or recessed surface can be formed by deep reactive ion etching or by wet etching. The cavity or recessed surface can be a recessed surface and can be manufactured using drilling, lasers, or 3D printing. The cavity or recessed surface can be filled with a liquid to a level below the top level, where the liquid is a composition that maintains its structural format under processing conditions for capping the liquid in the cavity or recessed surface. The liquid can be capped in the substrate by conformally depositing parylene on and contacting the liquid such that the parylene prevents the liquid from leaking out of the cavity or recessed surface, embedding the liquid in the cavity or recessed surface of the substrate. Variations can include other features discussed herein.

[0051] In an embodiment, an article of manufacture can include a substrate, a liquid in a cavity or recessed surface of the substrate, and a conformal parylene capping layer on and contacting the liquid. The conformal parylene capping layer can be structured such that the parylene prevents the liquid from leaking out of the cavity or recessed surface, embedding the liquid in the cavity or recessed surface of the substrate.

[0052] Variations of such an article of manufacture, its features, as taught herein, can include a number of different embodiments and features that may be combined depending on the application of such articles of manufacture, the format of such articles of manufacture, and/or the architecture in which such articles of manufacture are implemented. Features of such article of manufacture can include the conformal parylene capping layer on, contacting, and encapsulating combination of the substrate and the liquid in the cavity or recessed surface of the substrate.

[0053] Variations of such an article of manufacture can include the liquid only partially filing the cavity or recessed surface of the substrate. Variations can include the liquid being a silicone oil. Variations can include the liquid being a liquid metal. The liquid metal can be Galinstan. The liquid can be a coolant or a biological liquid. The liquid can have a composition that does not alter under conditions for conformally forming the parylene on the liquid in the cavity. The liquid can be a liquid that does not boil at 25 mTorr. Variations of such an article of manufacture can include the liquid being static in the cavity or recessed surface. Variations of such an article of manufacture can include a channel to flow the liquid in the cavity or recessed surface. The article of manufacture providing flowing capability to the liquid can be a device for lab on chip applications.

[0054] Variations of such an article of manufacture can include the substrate being a silicon substrate. Variations of such an article of manufacture can include the substrate being a biocompatible substrate. Variations of such an article of manufacture can include the article of manufacture being a part of a device that is implantable in a human.

[0055] Variations of such an article of manufacture can include the parylene being parylene-C. Variations of such an article of manufacture can include the parylene being a high temperature parylene. Other forms of parylene can be used as the conformal parylene capping layer in the article of manufacture. Variations of an article of manufacture can include other features discussed herein.

[0056] A parylene capping film can be used to protect liquids embedded into cavities from leakage from the cavities. Though parylene-C was discussed in this disclosure due to the ability of parylene-C to be applied as a thicker layer, varying thickness of parylene may be used. In addition, higher temperature parylene can be used to avoid wrinkles and thermal mismatches, which could be an operational specification of a liquid-embedded structure for high-temperature operations. Parylene-C can be a good capping layer for room-temperature applications. Testing showed that a parylene capping film can be successfully deposited onto various liquids and liquids with various viscosities. Such parylene capping layers held up to accelerated temperature testing in air and submerged soaking as well as mechanical testing. Parylene be a highly effective packaging method for preventing liquid leakage in MEMS packaging or packaging with similar specifications.

[0057] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. Upon studying the disclosure, it will be apparent to those skilled in the art that various modifications and variations can be made in the devices and methods of various embodiments of the invention. Various embodiments can use permutations and/or combinations of embodiments described herein. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is to be understood that the above description is intended to be illustrative, and not restrictive, and that the phraseology or terminology employed herein is for the purpose of description.