CN1735708A - Apparatus and method for controlled application of reactive vapors to produce thin films and coatings - Google Patents

Abstract

A vapor deposition method and apparatus for applying thin layers and coatings on a substrate is disclosed. The method and apparatus are useful in the manufacture of electronic devices, micro-electro-mechanical systems (MEMS), Bio-MEMS devices, micro-nano imprint lithography, and microfluidic devices. The apparatus for performing the method provides for the addition of precise amounts of each reactant to be consumed in a single reaction step of the coating formation process. The apparatus provides for the precise addition of different combined amounts of reactants in a single step or when there are many different individual steps in the coating formation process. The precise addition of each reactant in vapor form is dosed into a predetermined set volume to a specified pressure at a specified temperature to provide a highly accurate amount of reactant.

Description

Apparatus and method for controlled application of reactive vapors to produce thin films and coatings

This application is related to the provisional application Serial No.60/482,861 submitted on June 27, 2003 entitled "Method and Apparatus for Mono-Layer Coatings"; submitted on September 30, 2003 entitled "Method of Thin Film Deposition" Provisional Application Serial No. 60/506,864; and Provisional Application Serial No. 60/509,563, filed October 9, 2003, entitled "Method of Controlling Monolayer Film Properties."

technical field

The present invention relates to apparatus and methods useful for depositing coatings on substrates, wherein the coatings are formed from chemically reactive species in the form of vapors that react with the surface of the substrate.

Background technique

Both integrated circuit (IC) device fabrication and microelectromechanical system (MEMS) fabrication utilize multiple layers or coatings of material deposited on a substrate for various purposes. In some instances, multiple layers are deposited on a substrate and then removed sequentially, such as when the layers are used as mask material for patterning and then removed sequentially after the pattern is transferred onto the underlying layer when. In other examples, multiple layers are deposited to perform functions in a device or system and remain as part of the fabricated device. There are many methods for depositing thin film layers or coatings, such as: sputter deposition, where a plasma is used to sputter atoms from a target material (usually a metal) and the sputtered atoms are deposited on the substrate; Chemical vapor deposition in which substances activated (e.g. by plasma, radiation or temperature or a combination thereof) react either in the gas phase (with the subsequent deposition of reaction products on the substrate) or on the substrate surface to deposit on the substrate evaporative deposition, in which the evaporated material condenses on the substrate to form a layer; and spin coating, spray coating or dip coating, usually from a solvent solution of the coating material, in which the solvent is subsequently evaporated to form a layer on the substrate. The coating material is left on the bottom.

In applications where coating abrasion may occur due to liquid flow or mechanical contact on the substrate surface on which the coating layer is located, in order to obtain specific surface properties, the coating is directly chemically bonded to the substrate by reacting the species with the surface. Substrate surfaces are helpful.

Areas of particular interest for layers and coatings that are chemically bonded to substrate surfaces are those of integrated circuit systems and their integration with mechanical systems, known as microelectromechanical systems or MEMS. Due to the nanometer scale of some electronic devices formed, and due to the use of MEMS in applications such as biological sciences, there is an increased need for improved methods of controlling the formation of coatings or layers on substrate surfaces, wherein in the In applications such as biological sciences, the type and nature of coatings on a substrate surface are used to provide specific functionality to the surface. Historically, these kinds of coatings were deposited in the liquid phase, resulting in loss of device yield and limited film property control due to capillary forces. Recently, vapor deposition has been used as a method to replace liquid processing and to improve the properties of coatings.

For the purpose of illustrating a few of the many potential applications of vapor phase coatings that must be deposited to have specific critical properties and/or have specific permanent structural orientations with respect to the underlying substrate, applicants would like to Reference is made to the following publications or patents dealing with coating formation methods. Applicant wishes to state that some of this background art is not prior art to the present invention as it was published after the invention date of Applicant's invention. It is mentioned here because of its relation to the general subject matter.

Product applications using coatings deposited by vapor on substrate surfaces include the following by way of example and not limitation. US Patent 5,576,247 entitled "Thin layer forming method where hydrophobicmolecular layers preventing a BPSG layer from absorbing moisture", granted to Yano et al. on November 19, 1996. US Patent No. 5,602,671, issued February 11, 1997 to Hornbeck, describes low surface energy passivation layers for use in micromechanical devices. Specifically, aligned monolayers are used to confine the van der Waals forces between two components to reduce the attraction between the component surfaces. Steven A. Henck's article titled "Lubrication of digital micromirror devices" in Tribology Letters 3 (1997) 239-247 describes nearly 50 lubricants that have been studied for use in digital micromirror devices. These lubricants include self-assembled monolayer (SAMs) lubricants, fluid lubricants and solid lubricants. Lubricants are used to reduce adhesion between coating surfaces in microelectromechanical systems (MEMS) devices. In the article by YuchunWang et al., titled "Vapor phase deposition of uniform and ultrathinsilanes", SPIE Vol. 3258-0277-786X(98) 20-28, the authors describe that in biomedical applications such as microfabricated silicon filters, Uniform, conformal, and ultrathin coatings on the surface of microdevices to tune hydrophilicity and minimize non-specific protein adsorption. In the article titled "Gold nanoparticulate film bound to silicon surface with self-assembled monolayers" published in Thin Solid Films 327-329 (1998) 591-594 by JianWang et al., discussing the use of SAM for surface preparation to bond gold nanoparticles approach to the silicon surface.

Patrick W. Hoffmann et al. in American Chemical Society, Langmuir 1997, 13, 1877-1880 describe molecular orientation in monomolecular thin organic films and surface coverage on Ge/Si oxides. Gas-phase reactors have been reported to provide precise control over surface hydration and reaction temperature during the deposition of monofunctional perfluorinated alkylsilanes. While some process conditions are provided, the equipment used to coat the film is not described. TMMayer et al. describe "Chemical Vapor deposition of fluoroalkylsilane monolayer films for adhesion control in microelectromechanical systems" in J.Vac.Sci.Technol.B 18(5), Sep/Oct 2000. This article mentions the use of remotely generated microwave plasma to clean silicon oxide substrate surfaces prior to film deposition, where the plasma source gas is water vapor or oxygen. US Patent No. 6,203,505, issued March 20, 2001 to Jalisi et al., describes a guide wire with a vapor-deposited primer layer. The guidewire is an intraluminal device with an adhesive primer layer formed from a carbonaceous material and a lubricious topcoat layer from a hydrophilic polymeric material. A preferred coating method for applying the carbon based coating is chemical vapor deposition. The coating is a plasma polymerized coating, so the resulting polymer is an amorphous structure with other groups in the structure than the monomeric groups of the source material. For example, plasma-polymerized polyethylene may contain various functional groups, such as vinyl groups, in addition to methylene groups. In their title "Amino-terminated self-assembled monolayer on a SiO ₂ surface formed by chemical vapor deposition", J.Vac.Sci.Technol.A 19(4), Jul/Aug.2001, Atsushi Hozumi et al. describe Self-assembled monolayers (SAMs) were formed on n-type Si(100) wafers that were photochemically cleaned by UV/ozone treatment, thereby forming a thin _SiO2 layer on the silicon surface. The SAM coating was applied by placing the cleaned wafer together with the silane liquid precursor diluted with pure toluene into a vessel with a dry nitrogen atmosphere. The container was sealed with a lid and heated in a furnace maintained at 373K.

International Patent Application No. PCT/US01/26691, published April 11, 2002, describes a substrate having a hydrophobic surface coating consisting of the reaction product of a chlorosilyl compound and an alkylsilane . In a preferred embodiment, the hydrophobic coating is formed by simultaneous aqueous vapor deposition of chloroalkylsilanes and chlorosilyl-containing compounds to form an anchor layer that can then be covered with a hydrophobic coating. The reactants were reported to be vapor-deposited simultaneously in a closed humidity-controlled chamber. Dry air, moist air, or dry air saturated with coating precursor vapor is introduced at one end of the chamber and exhausted at the other end. Reportedly, the reaction precursors were introduced into the reaction chamber by flowing dry air through the precursor liquid and into the chamber. US Patent No. 6,383,642 issued May 7, 2002 to Le Bellac et al. describes the formation of hydrophobic/oleophobic coatings on substrates such as glass or plastic materials. The coating precursor is introduced into a chamber utilizing a pulsed plasma, while the frequency of the plasma generation source ranges from 10 kHz to 10 GHz at a power from 100 to 2000 W, where the surface area of the substrate to be coated is 0.4 ^M2 . The precursors were introduced into the chamber at various flow rates to establish and maintain pressures in the chamber ranging from 0.1 to 70 Pa.

In an article published by Elsevier Science BV in Sensors and Actuator A 104 (2003) 213-221, W. Robert Ashurst et al discusses a method of applying an anti-stick coating for MEMS by vapor phase application. Specifically, silicon (100) samples cut from a P-doped n-type test wafer were rinsed in acetone and then cleaned by exposure to UV light and ozone for 15 minutes. Before entering the vapor deposition chamber, the samples were treated with concentrated HF for 10 min and then cleaned as described above. In the vapor deposition chamber, the silicon substrate is additionally cleaned of any organic contaminants using an oxygen plasma generated in the coating chamber but at a sufficient distance from the sample so that the sample can be The plasma species are in contact and not within the plasma discharge region. After the _O2 plasma exposure started, water vapor was dosed into the chamber and eventually replaced the oxygen. Water is added to form -OH surface end groups on the substrate surface. The coating was applied by first feeding water vapor into the chamber until the pressure in the chamber exceeded 5 Torr. Next, the chamber is evacuated to the desired water vapor pressure between 1 and 1.3 Torr. Subsequently, a dimethyldichlorosilane (DDMS) precursor was introduced into the process chamber until the total pressure was in the range of 2.5-3 Torr. The reaction was carried out for 10-15 minutes, after which time the chamber was evacuated and purged with nitrogen. It is concluded that increasing the substrate temperature during coating over the range of 20°C to 50°C, all other variables being equal, results in films with reduced water contact angles. The main result of the temperature experiments was reported to be that it was not necessary to heat the sample. In "Vapor Deposition of Amino-Functionalized Self-Assembled Monolayers on Mems", "Reliability, Testing, and Characterization of MEMS MOEMS II", Rajeshuni Ramesham, Danelle M. Tanner, Editors, Proceedings of SPIE Vol.4980 (2003) In the second article, authors Matthew G. Hankins et al. describe micromotor test devices coated with membranes made from amino-functional silanes. The coating was applied in a vapor-deposited self-assembled monolayer system developed at Sandia National Laboratories. The process variables used to deposit the coatings are not discussed in the article.

US Patent No. 6,576,489 issued June 10, 2003 to Leung et al. describes methods of forming microstructured devices. The method includes using alkylsilane-containing molecules in the vapor phase to form a coating on a substrate surface. The alkylsilane-containing molecules are introduced into the reaction chamber containing the substrate by bubbling anhydrous inert gas through a liquid source of the alkylsilane-containing molecules to transport the molecules in the gas phase into the reaction chamber. The formation of the coating is carried out at temperatures ranging between about 15°C and 100°C on the substrate surface, while the pressure in the reaction chamber is reported to be below atmospheric pressure, but still high enough that an appropriate amount of alkylsilane-containing molecules is present for rapid coating formation. The liquid source of alkylsilane molecules may be heated to increase the vapor pressure of the alkylsilane-containing molecules.

Although the various methods that can be used to apply layers and coatings to semiconductor devices and MEMS have been discussed above, and there are some descriptions of the various apparatus that can be used to deposit coatings, there is very little description of the apparatus . The references below relate more to the device. _U.S. Patent Application Publication No. US 2001/0028924Al, published October 11, 2001, by Arthur Sherman, relates to a continuous chemical vapor deposition process for depositing materials such _{as SiOx} , _Al2O3 , _TiO2 , _Si3N4 , SiO _x N _y , and inorganic material layers such as aluminum films doped with copper and silicon. United States Patent Application Publication No. US 2002/0076507 Al, published June 20, 2002 to Chiang et al., describes an atomic layer deposition (ALD) process based on the sequential supply of at least two separate reactants into a process chamber. The first reactant reacts (becomes adsorbed) with the surface of the substrate by chemisorption. The first reactant gas is removed from the process chamber, and the second reactant gas reacts with the adsorbed reactant to form the desired monolayer of the film. This process is repeated to form layers with the desired thickness. To reduce processing time, a separate purge gas is not used to purge the first reactant gas from the chamber prior to introducing the second gas comprising the second reactant. Alternatively, the purge gas also contains a second reactant. Several valve systems for gas flow providing various gas mixtures are described in detail.

The above background information provides a number of methods for producing coatings with considerable commercial applicability. Apparatus described for the manufacture of layers or coatings for use in electronic and/or MEMS devices, enabling the application of layers or coatings, but in terms of the amount of gas-phase reactant provided to the surface of a substrate , does not provide sufficient precision and repeatability. As a result, the exact composition of the desired layer or coating may not be obtained. At other times, due to improper ratios of the various reactants relative to each other, or supersaturation of the precursors, the reactants may polymerize and/or particle agglomerates may form as surface contaminants. Furthermore, the lack of control over the precise amounts of reactants supplied to the coating forming process reduces the ability to reliably produce the same coating multiple times. This reduces product yield and affects the commercial viability of the coating process. It would be highly desirable to have a more accurate and reliable method of supplying precise amounts of reactants to the processing chamber and to the substrate surface for coating formation.

Contents of the invention

We have developed an improved vapor deposition method and apparatus for applying layers and coatings on substrates. The method and apparatus are useful in the fabrication of electronic devices, microelectromechanical systems (MEMS), Bio-MEMS devices, and micro-fluidics devices. The coating formation method employs batchwise addition and mixing of all reactants consumed in the coating formation process. The coating formation process may be accomplished in one step, or may comprise a number of individual steps, in which a different or repeated reaction process is carried out in each individual step. The apparatus for carrying out the method provides for the addition of the precise amounts of the respective reactants to be consumed in one reaction step of the coating formation process. The device can provide precise additions of different combinations of reactants in one step or when there are many different individual steps in the coating formation process. The precise addition of each reactant is based on a dosing system where the amount of reactant added in a single step is carefully controlled. Specifically, reactants in vapor form are dosed into a vapor cell having a predetermined set volume at a specified temperature to a specified pressure to provide highly precise amounts of the reactants. The total measured amount of each reactant is transferred in a batch-wise manner into a processing chamber where the coating is formed. The order in which the reactants are added to the chamber for a given reaction step is optional and may depend on the relative reactivity of the reactants when more than one reactant is present, having one reactant or catalyst contact the lining first bottom surface requirements, or a balance of these considerations.

In some instances, it may be necessary to perform a series of individual vapor delivery steps to provide a complete coating rather than a continuous reaction process. For example, the entire precisely measured amount of one reaction component may be added first, followed by the addition of a series of precisely measured amounts of the second reaction component. In each case, the entire measured quantity was added to the reaction chamber. This provides precise, carefully measured amounts of reactants at precise times for each reactant.

A computer-driven process control system can be used to provide a series of additions of reactants to the processing chamber in which the layer or coating is formed. The process control system typically also controls other process variables such as (for example and not limitation) processing time, chamber pressure, temperature of the processing chamber and substrate to be coated, and vapor delivery lines and vapor pool relative to the precursor body temperature.

The apparatus for vapor deposition of coatings is particularly useful for the deposition of coatings having thicknesses in the range from about 5 angstroms to about 1000 angstroms, (and can be used for increased coating thicknesses), wherein, for forming coatings At least one precursor of the layer exhibits a vapor pressure of less than about 150 Torr at a temperature of 25°C. The device includes: at least one precursor container, wherein the at least one precursor is placed in a liquid or solid form; at least one precursor vapor pool is used to store the vapor of the at least one precursor; at least one device controls a flow of precursor vapor from the precursor container into the precursor vapor pool; a pressure sensor in communication with the precursor vapor pool; a process controller that receives data from the pressure sensor and The data is compared to a desired nominal vapor pool pressure and a signal is sent to a device controlling vapor flow from the precursor container into the precursor vapor pool so that when the desired nominal pressure is reached, preventing further entry of the vapor stream into the precursor vapor pool; a device for controlling the flow of precursor vapor into the precursor vapor pool upon receipt of a signal from the process controller; a processing chamber for converting the a coating is vapor deposited on a substrate in the processing chamber; and a device for controlling the flow of precursor vapors into the processing chamber upon receipt of a signal from the process controller.

In some examples, the apparatus includes a device that applies heat to the precursor while the precursor is in the container to generate a vapor phase of the precursor. Typically, the apparatus comprises: at least one catalyst container, in which the catalyst is placed in liquid or solid form; and a catalyst vapor pool for holding the vapor of the catalyst, the apparatus having the same aids as those described with reference to the precursor catalyst to the process chamber The basic element of transmission.

The method of the present invention is used for the vapor deposition of coatings, wherein at least one precursor used to form the coating exhibits a vapor pressure of less than about 150 Torr at a temperature of 25°C. The method comprises the steps of: a) providing a process chamber in which the coating is vapor-phase deposited; b) providing at least one precursor which at a temperature of 25° C. exhibits a vapor pressure of less than about 150 Torr; c) transporting the vapor of said precursor to a precursor vapor pool where said precursor vapor accumulates; d) accumulating said vapor phase coating deposition required a nominal amount of said precursor vapor; and e) adding said nominal amount of said precursor vapor to said processing chamber in which said coating is deposited. Typically, at least one catalyst vapor is added to the processing chamber in addition to the at least one precursor vapor, wherein the relative amounts of catalyst and precursor vapor are based on the physical properties that the coating is intended to exhibit.

Description of drawings

FIG. 1 shows a schematic cross-sectional view of an apparatus 100 for vapor deposition of coatings using the present invention to meter precise amounts of reactants to the coating formation process.

Fig. 2 shows a schematic cross-sectional view of an apparatus 200 of the type shown in Fig. 1 in which many substrates are processed simultaneously.

Figure 3 schematically illustrates a system 300 of the type that can be used to fabricate MEMS devices, where there are moving parts formed by the release etch process in system 304, and where, after the release etch process, the MEMS The device is transferred through a pressure controlled channel 306 to a coating application chamber 302 of the type described with reference to FIG. 1 .

Detailed ways

As a prelude to the Detailed Description, it should be noted that, as used in this specification and the appended claims, the singular forms "a" and "the" include plural referents unless the context clearly dictates otherwise.

We have developed an improved vapor deposition method and apparatus for applying thin (typically 5 angstroms to 1,000 angstroms thick, in some cases up to about 2,000 angstroms thick) films or coatings onto semiconductor device substrates or microstructures. Electromechanical system components. When at least one of the reactants or catalysts used in the formation of the coating must be evaporated before use, and when it must be available in the amount available for the reaction, the time available for the reaction at a given process pressure, or The present method and apparatus are used where a combination of the two allows careful control of the amounts of each reactant. This method is particularly useful in the deposition of thin films or coatings, wherein the thickness of the film or coating ranges from about 5 Angstroms to about 500 Angstroms, and the method provides excellent coating thickness in the range of about 300 Angstroms. the result of.

As discussed earlier herein, such thin layers or coatings have a wide variety of applications. For purposes of illustration, applicants will describe the method and apparatus of the present invention in terms of tunable deposition of organic monolayers; however, those skilled in the art of layer and coating deposition will be able to apply the concepts described to non-organic coatings. layer and/or non-monolayer.

There is now particular interest in the anti-stiction layers and coatings required to enable long-term reliable performance of MEMS. Adhesion (adhesion) of flexible MEMS components is one of the key reliability issues which has proven difficult to overcome. Traditionally, solution-based anti-adhesion monolayers have been used; however, more recently, due to the unsatisfactory quality, scalability and reproducibility of the membranes produced due to relatively lengthy wet processing, capillary sticking, particulate problems , people began efforts to develop vapor deposition methods for anti-adhesion coatings. Overall, vacuum processing and vapor deposition of anti-stiction coatings, including self-assembled monolayers, have provided higher quality films. An integrated vapor deposition process (including surface plasma treatment in the same chamber) generally provides better control over surface reactivity while avoiding the potential for sticking between MEMS components during application of the anti-stiction coating.

The embodiments described in the examples below relate to the application of an organic SAM coating, wherein the organic SAM coating is applied on the surface of a single crystal silicon substrate using a vapor deposition technique. Apparatus for depositing such coatings is available from Applied Microstructures, Inc. of San Jose, California. The apparatus is specifically designed to provide a high degree of control over the quantities of reactants supplied to the coating application process chamber for each individual process step and the timing and sequence in which these reactants are made available for reaction.

The properties of the deposited films were evaluated using standard surface analysis methods, cantilever beam array test structures and the performance of working MEMS devices.

I. Apparatus for Vapor Deposition of Thin Coatings

FIG. 1 shows a schematic cross-sectional view of an apparatus 100 for vapor deposition of thin coatings. Apparatus 100 includes a process chamber 102 in which a thin (typically 5 Angstroms to 1,000 Angstroms thick) coating is vapor-deposited. The substrate 106 to be coated is placed on the substrate holder 104 , typically in a recess 107 of the substrate holder 104 . Depending on the chamber design, the substrate 106 may be placed at the bottom of the chamber (not shown in this position in FIG. 1 ). A remote plasma source 110 connected via a valve 108 is mounted to the processing chamber 102 . The remote plasma source 110 can be used to provide a plasma that is used to clean and/or convert the substrate surface to a specific chemical state (which makes the coating species and/or The catalyst can react with the surface, thereby improving the adhesion and/or formation of the coating); or the remote plasma source 110 can be used to provide modification of the coating during formation of the coating (not shown) or after deposition useful substances in the process. Plasma can be generated using microwave, DC or inductive RF power or a combination thereof. The processing chamber 102 utilizes an exhaust port 112 to remove reaction by-products and is opened to pump/purge the chamber 102 . A shutoff or control valve 114 is used to isolate the chamber, or to control the amount of vacuum applied to the exhaust port. The vacuum source is not shown in FIG. 1 .

Apparatus 100 is shown in FIG. 1 to illustrate vapor deposition coatings using two precursor materials and a catalyst. Those skilled in the art will understand that one or more precursors and zero to more catalysts may be used during vapor deposition of the coating. Catalyst storage vessel 116 houses catalyst 154, which may be heated, if necessary, by heater 118 to provide vapor. It should be understood that the walls of the precursor and catalyst storage containers and the transfer lines into the process chamber 102 will be heated if necessary to maintain the precursor or catalyst in a vapor state to minimize or avoid condensation. The same applies to the heating of the inner surfaces of the processing chamber 102 and the surface of the substrate 106 to which a coating (not shown) is to be applied. Control valve 120 is located on transfer line 119 between catalyst storage vessel 116 and catalyst vapor pool 122 in which catalyst vapor is allowed to accumulate until a nominal prescribed pressure is measured at pressure indicator 124 . The control valve 120 is in the normally closed position and returns to this position once the specified pressure is reached in the catalyst vapor pool 122 . When catalyst vapor in vapor pool 122 is to be released, valve 126 on transfer line 119 is opened to allow catalyst in vapor pool 122 to pass into process chamber 102 at low pressure. Control valves 120 and 126 are controlled by a programmable process control system (not shown in FIG. 1 ) of the type known in the art.

The precursor 1 storage container 128 accommodates the coating reactant precursor 1, and if necessary, the precursor 1 may be heated by a heater 130 to provide vapor. As previously described, the internal surfaces of the precursor 1 delivery line 129 and vapor pool 134 are heated, if necessary, to maintain the precursor 1 in a vapor state, thereby avoiding condensation. Control valve 132 is located on transfer line 129 between Precursor 1 storage container 128 and Precursor 1 vapor pool 134 in which Precursor 1 vapor is allowed to accumulate until pressure indicator 136 Measured at the rated specified pressure. The control valve 132 is in the normally closed position and returns to this position once the specified pressure is reached in the precursor 1 vapor pool 134 . When the Precursor 1 vapor in the vapor pool 134 is to be released, the valve 138 on the transfer line 129 is opened to allow the Precursor 1 vapor in the vapor pool 134 to enter the processing chamber 102 at low pressure. Control valves 132 and 138 are controlled by a programmable process control system (not shown in FIG. 1 ) of the type known in the art.

The precursor 2 storage container 140 accommodates the coating reactant precursor 2, and if necessary, the precursor 2 may be heated by a heater 142 to provide vapor. As previously mentioned, the internal surfaces of the precursor 2 delivery line 141 and the vapor pool 146 are heated, if necessary, to keep the precursor 2 in a vapor state, thereby avoiding condensation. Control valve 144 is located on transfer line 141 between Precursor 2 storage container 140 and Precursor 2 vapor pool 146 in which Precursor 2 vapor is allowed to accumulate until pressure indicator 148 Measured at the rated specified pressure. The control valve 144 is in the normally closed position and returns to this position once the specified pressure is reached in the precursor 2 vapor pool 146 . When the precursor 2 vapor in the vapor pool 146 is to be released, the valve 150 on the transfer line 141 is opened to allow the precursor 2 vapor in the vapor pool 146 to enter the process chamber 102 at low pressure. Control valves 144 and 150 are controlled by a programmable process control system (not shown in FIG. 1 ) of the type known in the art.

During the process of forming a coating (not shown) on the surface 105 of the substrate 106, a catalyst 154 at least equal to a vapor pool 122, or a precursor 1 of a vapor pool 134, or a vapor pool 146 can be added to the processing chamber 102. Incremental vapor of the precursor 146 . The total amount of vapor added is controlled by both the adjustable volume size of each expansion chamber (typically 50 cc up to 1,000 cc) and the amount of vapor injection (dose) into the reaction chamber. Additionally, a process control system (not shown) may adjust the set pressure 124 of the catalyst vapor pool 122, or the set pressure 136 of the precursor 1 vapor pool 134, or the set pressure 148 of the precursor 2 vapor pool 146, to The amount of catalyst or reactant added to any particular step during the coating formation process is adjusted. This ability to fix precise amounts of catalyst and coating reactant precursors that are dosed (charged) into the process chamber 102 at any time during coating formation allows precise addition of the precursors at precise time intervals. and catalyst amount, which not only provides precise dosing of reactants and catalyst, but also provides repeatability with respect to addition time.

Despite the fact that many precursors and catalysts are often relatively non-volatile materials, this setup provides a very inexpensive yet precise method of adding gas-phase precursor reactants and catalysts to the coating formation process. In the past, flow controllers have been used to control the addition of various reactants; however, due to the low vapor pressure and chemical properties of the precursor materials, these flow controllers may not be able to handle some precursors used for coating vapor deposition. The rate of vapor generation from certain precursors is often too slow to operate with flow controllers in a manner that provides material availability in a timely manner for the vapor deposition process.

This device allows the vapor to build up to a sufficient amount to charge (dosage) the reaction. If it is desired to take several doses as the coating deposition progresses, the device can be programmed to do so as described above. Furthermore, adding reactant vapors to the reaction chamber in controlled portions (as opposed to continuous flow) greatly reduces the amount of reactant used and lowers the cost of the coating process.

FIG. 2 shows a schematic cross-sectional view of an embodiment of a vapor deposition processing apparatus 200 that provides the application of thin coatings to multiple substrates 206 simultaneously. Apparatus 200 includes a process chamber 202 in which a thin (5 Angstrom to 1,000 Angstrom thick) coating is vapor-deposited. A plurality of substrates 206 to be coated are placed on a substrate holder 204 which can be moved in the processing chamber 202 by means of a device 209 . A remote plasma source 210 connected via a valve 208 is mounted to the processing chamber 202 . The remote plasma source 210 can be used to provide plasma that is used to clean and/or react with (activate) the substrate surface prior to applying the coating, or the remote plasma source 210 can be used to provide Substances useful during or after the formation of the coating (not shown). As previously mentioned, the plasma can be generated using microwave, DC or inductive RF power or a combination thereof. The process chamber 202 utilizes an exhaust port 212 to remove reaction by-products and to pump/purge the chamber 202 . Control valve 214 is used to control the speed of vacuum pumping and evacuation (vacuum generator not shown).

The apparatus 200 shown in FIG. 2 is used to illustrate vapor deposition coatings using two precursor materials and a catalyst. Those skilled in the art will understand that one or more precursors and zero to more catalysts may be used during vapor deposition of the coating. Catalyst used during the coating deposition process enters process chamber 202 from a catalyst vapor pool (not shown) through line 219 through control valve 220 . Precursor 1 used during the coating deposition process enters process chamber 202 from Precursor 1 vapor pool (not shown) through line 217 through control valve 218, and Precursor 2 from Precursor 2 vapor pool (not shown) ) enters the processing chamber 202 through the pipeline 215 through the control valve 216. As previously mentioned, the transfer lines for the catalyst, Precursor 1 and Precursor 2 were heated if necessary to keep these materials in a vapor state and thus avoid condensation. Catalyst, Precursor 1 and Precursor 2 may be distributed in process chamber 202 by a distribution system 205, which typically contains separate distribution channels for the catalyst and each precursor used in the coating deposition process. The flow distribution system helps ensure uniform distribution of the individual reactive component materials throughout the processing chamber 202 . Process chamber 202 typically utilizes a swing door or load lock 226 . Once the reaction is complete, the process by-products exit the process chamber 202 through an exhaust port 212 connected to a vacuum pump (not shown). The interior surfaces of processing chamber 202 and other devices such as flow distribution system 205 are often heated to prevent condensation of catalyst, Precursor 1 and Precursor 2 on these device surfaces. The reaction pressure is often determined by the amount of reactants injected into chamber 202 . The process chamber pressure is monitored by a pressure sensing device 224, which cooperates with the aforementioned vapor delivery system through a computerized control system (not shown). The flow control valve 214 is used to remove the entire vapor and by-products from the interior of the process chamber 202 . The flow control valve 214 can be operated in conjunction with a pressure sensing device by a computerized control system to maintain the desired pressure during the pumping/purging steps.

FIG. 3 shows a schematic cross-sectional view of a MEMS processing system 300 using a release etch process chamber 310 (the type used to fabricate mechanically-characterized movable elements in MEMS devices) and referring to FIG. 1 and FIG. 2 vapor deposition coating application system 312 of the aforementioned type. Release etch process chamber 310 includes means for reagent entry 324 (shown as a single line for convenience, but it could be multiple lines), pressure sensing and monitoring equipment 326, exhaust port 334 with flow control valve 332, and again The recirculation loop 331, in which the pump 330 is optional, but can be used to provide important processing advantages. Vapor deposition coating apparatus process chamber 308 includes reagent (catalyst and precursor) entry means 312 (shown as a single line for convenience, but it could be multiple lines), pressure sensing and monitoring means 314, and control Discharge port 322 of valve 320 . Release etch process chamber 310 and vapor deposition coating process chamber 308 are joined to each other by isolation valve system 306 .

II. Exemplary Methods of the Invention

As discussed for the device, there are problems in providing precisely measured amounts of reactants to a vapor deposition coating system on a repeatable basis. This is because many precursor materials used for coating formation have low vapor pressure or are not compatible with mass flow controllers. Furthermore, for many vapor deposited coatings, water acts as a catalyst for coating formation, and the amount of water present in the coating deposition chamber is not precisely controlled.

When the surface of the feature to be coated is in the nanometer size range, it is critical that the coating deposition is carefully controlled to provide a coating of the desired thickness (typically about 5 angstroms to 1000 angstroms, and in some instances up to 2000 Angstroms), and no particles or agglomerates were formed in the deposited coating. In order to meet these critical requirements for thin vapor-deposited coatings, it is necessary to provide precisely measured quantities of reactants and catalysts, and to control the period of time over which these precisely measured quantities are delivered to the substrate surface or deposition chamber. Delivery to the substrate surface depends on the internal design of the process chamber, and there are well known techniques in the field of chemical vapor deposition for delivering reagents to the substrate surface. The present method solves the problem of providing precisely measured amounts of reactants and catalysts delivered to the coating deposition chamber in the proper order and at the proper time.

By way of example and not limitation, the provision of precise amounts of reactants and catalysts will be described for monomolecular coatings of chlorosilanes and alkylsilanes used in many applications such as MEMS, BioMEMS and microfluidics. In general, organic precursor materials such as, but not limited to, silanes, chlorosilanes, fluorosilanes, methoxysilanes, alkylsilanes, and aminosilanes are useful. By way of example and not limitation, some specific precursors used to make coatings are perfluorodecyltrichlorosilane (FDTS), undecenyltrichlorosilane (UTS), vinyltrichlorosilane (VTS), decyl Trichlorosilane (DTS), Octadecyltrichlorosilane (OTS), Dimethyldichlorosilane (DDMS), Dodecenyltrichlorosilane (DDTS), Fluorotetrahydrooctyldimethylchlorosilane (FOTS), perfluorooctyldimethylchlorosilane, aminopropylmethoxysilane (APTMS), perfluoropropylmethyldichlorosilane, and perfluorodecyldimethylchlorosilane. OTS, DTS, UTS, VTS, DDTS, FOTS and FDTS are all trichlorosilane precursors. For OTS, DTS, and UTS, the other end of the precursor chain is a saturated hydrocarbon; for VTS and DDTS, vinyl functionality; and for FDTS, fluorine atoms (which also have fluorine atoms along most of the chain length). Other useful precursors include 3-aminopropyltrimethoxysilane (APTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) which provide amino functionality. Those skilled in the art of organic chemistry will appreciate that vapor-deposited coatings derived from these precursors can be engineered to provide specific functional properties to the coated surface. For example, the surface to be coated can be silicon, glass, organic (plastic) or metal.

Most silane-based precursors, such as commonly used dichlorosilane and trichlorosilane by way of example but not limitation, tend to agglomerate on the substrate surface during coating formation. These agglomerations may lead to structural failure or sticking. Such agglomeration is due to partial hydrolysis and polycondensation of polychlorosilanes. This agglomeration can be prevented by precise metering of moisture in the process environment as a source of hydrolysis, and by careful control of the metering of chlorosilane precursors available to the coating formation process.

Those working in the MEMS field have recognized the advantages of vapor deposited coatings over coatings applied using liquid based dip, spray and spin coating techniques. For example, some of these advantages include: elimination of sticking caused by capillary forces; control over the coating environment (especially the amount of moisture present); on micro- and nano-sized patterns such as microchannels and holes Uniform coating characteristics; solvent-free process with no contamination; and faster process compatible with MEMS clean room processing specifications.

For example, a DDTS precursor can be used in combination with a water catalyst in a vapor deposition process using one precursor and catalyst. In a vapor deposition process using two precursors and one catalyst, for example and without limitation, a DDTS precursor, a UTS precursor, and a water catalyst may be used in combination. The relative amounts of DDTS and UTS precursors can be adjusted to provide different overall functional properties to the coated surface. However, the ability to control the properties of the coated surface and to reliably replicate these properties depends on the ability to control the relative amounts of DDTS and UTS precursors supplied to the coating formation process. This ability depends on providing such precisely controlled quantities, which is possible when using the method of the present invention.

When the precursors used to form the initial vapor-deposited coating have potentially reactive functional groups on the exposed surface of the coating, these functional groups can be further reacted with other chemical compounds to modify the functionality of the coating surface.

In addition to organosilanes, polyethylene glycol (PEG) can also be used alone or in combination with other film-forming compounds such as silanes to provide biotechnologically functional surfaces. A portion of the surface to be coated may be coated with the organosilane reaction product, while another portion may be coated with the PEG reaction product. Alternatively, organosilanes can include functional groups at the ends of the polymer chains away from the substrate surface, which can react with PEG reactants to place PEG functional groups on the ends of the polymer chains, thereby affecting the coating surface. Feature. For example, PEG membranes are known to reduce protein adsorption in microfluidic applications. The PEG3 film includes 6 carbons, while the PEG2 film includes 4 carbons. The length of the polymer chains can also be adjusted to provide desired film properties.

The present method for vapor deposition of coatings offers many advantages. Typically, a remote plasma source is used to generate a cleaning plasma (usually oxygen-containing) that can be used to remove contaminants from the substrate surface. When the substrate is silicon, the cleaning process is useful in the formation of -OH functional groups, which serve as bonding sites for many coating precursors such as trichlorosilane. By directly measuring the vapor pressure of the precursor at a given temperature and a known volume, precise control of the precursor volume is ensured. Process control is provided by varying the amount of precursor and partial pressure used in the gas phase reaction.

III. Description of General Parameters for Vapor Deposition of Molecular Coatings

The surface to be coated is usually pretreated in the same chamber. In order to achieve bonding of chlorine functional groups to the substrate surface, it is necessary to create OH-terminal sites on the surface. This can be achieved by treating the silicon surface with an oxygen plasma in the presence of moisture in the deposition chamber. The plasma can be generated using a remote power source of the type previously described. During exposure of the substrate to the oxygen plasma, the pressure in the processing chamber is typically in the range of from about 0.2 Torr to about 2 Torr, more typically in the range of from about 0.5 Torr to about 1 Torr. For a process chamber with a volume of about 2 liters, the plasma source gas oxygen flow rate is in the range of from about 50 seem to about 300 seem, more typically in the range of from about 100 seem to 200 seem. Substrate processing times are typically from about 1 minute to about 10 minutes, more typically from about 1 minute to about 5 minutes.

Coating deposition is typically carried out in a deposition chamber at a pressure ranging from about 100 mTorr to about 10 Torr, more commonly at a pressure ranging from about 0.5 Torr to about 5 Torr, and most commonly at a pressure ranging from about 0.1 Torr to about 3Torr range of pressure. The substrate deposition temperature depends on the specific coating precursor and substrate material. For silicon substrates, if the coating precursor is FOTS or DDMS, and used in conjunction with a water catalyst, the substrate temperature is typically in the range of about 20°C to about 60°C. To maintain these coating precursors in a vapor state prior to reaction, the interior surfaces of the coating deposition processing chamber are typically maintained at a temperature ranging from about 30°C to about 60°C. Using these coating precursors and specified reaction temperatures, the time required to prepare a continuous monolayer coating over the entire surface of a silicon substrate ranges from about 1 minute to about several hours, depending on the precursor Depending on the chemistry of the body and the substrate material, typical reaction times are in the range of 5 minutes to 30 minutes if the coating precursor is FOTS or DDMS.

For the deposition of anti-stick MEMS coatings from chlorosilane precursors, the following recipe and process were used. In each case, selected from the group consisting of dimethyldichlorosilane (DDMS), tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and heptadecafluoro-1,1, A precursor from the group consisting of 2,2-tetrahydrodecyltrichlorosilane (FDTS) was evaporated and used in combination with water vapor as a catalyst. In each instance, the precursors and water were degassed under vacuum prior to introduction into the system to remove dissolved gases. Conditions for outgassing vary depending on the precursor and catalyst, but those skilled in the art can readily determine appropriate outgassing conditions.

Referring to FIG. 1 , degassed water is placed in a catalyst storage vessel 116 and heated to a temperature of about 30° C. to generate steam, which accumulates through transfer line 119 in a vapor pool 122 which The volume is 300cc, and it is kept under the pressure of 16Torr. The DDMS precursor was placed in the Precursor 1 storage container 128 and heated to a temperature of 30° C. to generate a vapor, which was accumulated in the vapor pool 134 through the transfer line 129, the volume of the vapor pool 134 was 50 cc , and kept under the pressure of 50Torr. There is no precursor in the precursor 2 storage container 140 .

A silicon substrate 106 having a surface 105 is manually loaded onto the substrate holder 104 . The process chamber 102, with a volume of about 2 liters, was evacuated to about 20 mTorr and flushed with nitrogen before and after the coating reaction consisting of oxygen plasma treatment followed by coating deposition. The processing chamber 102 is vented to atmosphere. The process chamber 102 was then flushed (nitrogen to 10 Torr/pump to 0.7 Torr five times) with nitrogen. Surface 105 is treated with remotely generated oxygen plasma from plasma source 110 in the manner described above. Oxygen is introduced into the plasma generation source 110 through a mass flow controller (not shown). Based on the desired plasma dwell time for the process chamber 102, the oxygen flow rate for plasma generation was about 200 sccm. The pressure in the processing chamber 102 is about 0.6 Torr. Surface 105 of silicon substrate 106 was treated with oxygen plasma at a pressure of about 0.6 Torr for a period of about 5 minutes. The plasma processing is stopped and the process chamber 102 is evacuated to a base pressure of about 30 mTorr.

As described above, the water vapor cell 122 is filled with water vapor to a pressure of 16 Torr. The valve 126 between the water vapor pool 122 and the process chamber 102 is opened until the pressures of both are equal (for about 5 seconds) to about 0.8 Torr. The water vapor pool 122 is charged a second time with steam to 16 Torr, and this volume of steam is also poured into the processing chamber, so that the total water vapor pressure in the processing chamber 102 is about 1.6 Torr. As mentioned above, the DDMS vapor cell 134 has been filled with precursor vapor to 50 Torr, and immediately after the addition of water vapor is complete, the DDMS vapor is added. The valve 138 between the DDMS vapor pool 134 and the process chamber 102 is opened until the pressures of both are equal (for about 5 seconds) to about 4 Torr. The water and DDMS vapor were maintained in the processing chamber 102 for a period of 15 minutes. The process chamber is then pumped back to a base pressure of about 30 mTorr.

The processing chamber 102 was then flushed (nitrogen to 10 Torr/pump to 0.7 Torr) five times. The chamber is then vented to atmosphere, and the silicon substrate 106 is manually removed from the chamber.

The resulting coated surfaces are generally very hydrophobic as measured by the water contact angle, which is typically about 103° for DDMS films. The surface is exceptionally smooth with an RMS of 0.2nm and no visible particles or defects. Depending on the exact process/chemistry, the measured work of adhesion is reduced by a factor of 3000. Under the conditions provided above, the measured work of adhesion decreased to about 30 μJ ⁻² . The properties of the vapor-deposited films were equal to or better than those reported for the liquid-deposited films. Furthermore, the use of vapor deposition prevents sticking which often occurs during wet processing of substrates.

The above-described exemplary embodiments are not intended to limit the scope of the present invention, as those skilled in the art may, in light of this disclosure, extend these embodiments to correspond to the inventive subject matter claimed below.

Claims (25)

1. device that is used for the vapour deposition of coating, described coating has the thickness from about 5 dusts to about 1000 dust scopes, wherein, at least a presoma that is used to form described coating shows the vapour pressure that is lower than about 150Torr under 25 ℃ temperature, and described device comprises:

At least one precursor container is wherein placed described at least a presoma with liquid or solid form;

At least one precursor vapor pond is used to preserve the steam of described at least a presoma;

At least one equipment, control precursor vapor stream from described precursor container to described precursor vapor pond;

Pressure transmitter is communicated with described precursor vapor pond;

Process controller, described process controller receives data from described pressure transmitter, with the specified steam pond pressure ratio of described data and expectation, and send signal to the equipment of the steam flow of a control from described precursor container to described precursor vapor pond, so that when reaching the rated pressure of described expectation, prevent that steam flow from further entering in the described precursor vapor pond;

Control enters the equipment of the precursor vapor stream in the described precursor vapor pond when the signal of receiving from described first process controller;

Treatment chamber is used for the substrate of described coating vapour deposition at described treatment chamber; With

Control enters the equipment of the precursor vapor stream in the described treatment chamber when the signal of receiving from described process controller.

2. device as claimed in claim 1 comprises such equipment, and described equipment applies heat to described presoma when described presoma is in described container, to produce the vapor phase of described presoma.

3. as claim 1 or the described device of claim 2, wherein there are a plurality of precursor container and corresponding a plurality of steams pond.

4. device as claimed in claim 1, the add ons below wherein existing:

At least one catalyst container is wherein placed described catalyzer with liquid or solid form;

At least one catalyst vapor pond is used to preserve the steam of described at least a catalyzer;

At least one equipment, the steam flow of control from described catalyst container to described catalyst vapor pond;

Pressure transmitter is communicated with described catalyst vapor pond;

Process controller, described process controller receives data from described pressure transmitter, with the specified catalyst vapor pond pressure ratio of described data and expectation, and send signal to the equipment of the catalyst vapor stream of control from described catalyst container to described catalyst vapor pond, so that when reaching the rated pressure of described expectation, prevent that steam flow from further entering in the described catalyst vapor pond;

Control enters the equipment of the catalyst vapor stream in the described catalyst vapor pond when the signal of receiving from described process controller; With

Control enters the equipment of the catalyst vapor stream in the described treatment chamber when the signal of receiving from described the 4th process controller.

5. device as claimed in claim 4, wherein, all process controllers are arranged in a process controller.

6. as claim 4 or the described device of claim 5, comprise such equipment, described equipment applies heat to described at least a presoma when described at least a presoma is in described precursor container, to produce the vapor phase of described presoma.

7. as claim 4 or the described device of claim 5, comprise such equipment, described equipment applies heat to described at least a catalyzer when described at least a catalyzer is in described catalyst container, to produce the vapor phase of described catalyzer.

8. as claim 4 or the described device of claim 5, wherein there are a plurality of precursor container and corresponding a plurality of steams pond.

9. as claim 1 or claim 2 or claim 4 or the described device of claim 5, the scope of wherein said coat-thickness from about 5 dusts to about 500 dusts.

10. device as claimed in claim 9, the scope of wherein said coat-thickness from about 5 dusts to about 300 dusts.

11. a method that is used for the vapour deposition of coating, at least a presoma that wherein is used to form described coating shows the vapour pressure that is lower than about 150Torr under 25 ℃ temperature, and described method comprises:

A) provide treatment chamber, the described coating of vapour deposition in described treatment chamber;

B) provide at least a presoma, described at least a presoma shows the vapour pressure that is lower than about 150Torr under 25 ℃ temperature;

C) steam with described presoma is transferred to the precursor vapor pond, and described precursor vapor is built up in described precursor vapor pond;

D) build up the described precursor vapor that described gas phase deposits required specified rate; And

E) the described precursor vapor with described specified rate is added in the described treatment chamber, and described coating is deposited in described treatment chamber.

12. method as claimed in claim 11 is wherein used multiple presoma, and wherein builds up multiple presoma in a plurality of precursor vapor pond.

13. method as claimed in claim 12, at least two kinds in the wherein said precursor vapor substantially side by side are added in the described treatment chamber.

14. method as claimed in claim 12, at least two kinds in the wherein said precursor vapor are added in the described treatment chamber successively.

15. method as claimed in claim 11, wherein at least a catalyst vapor is added in the described treatment chamber, to help the vapour deposition of described coating.

16. method as claimed in claim 15, wherein said catalyst vapor was built up in the steam pond before being transferred to described treatment chamber.

17. method as claimed in claim 16, at least a substantially side by side being added in the described treatment chamber in wherein said catalyst vapor and the described at least a precursor vapor.

18. method as claimed in claim 16, at least a being added to successively in the described treatment chamber in wherein said catalyst vapor and the described precursor vapor.

19. method as claimed in claim 18, wherein said catalyst vapor was added in the described treatment chamber before precursor vapor being added in the described treatment chamber.

20. as claim 11 or the described method of claim 12, wherein by repeating step c), d) and e), at least a in the described at least a precursor vapor is added to the described treatment chamber from described steam pond more than once.

21. as claim 15 or the described method of claim 16, wherein by repeating to fill specified steam pond volume, afterwards described steam catalyst is repeated to be added to the described treatment chamber from described steam pond, at least a in the described at least a catalyst vapor is added to the described treatment chamber from described steam pond more than once.

22. as claim 11 or the described method of claim 12, wherein multiple precursor vapor is added in the described treatment chamber, and wherein adds described precursor vapor to obtain the required relative quantity of coating physical property.

23. as claim 15 or the described method of claim 16, wherein at least a catalyst vapor is added in the described treatment chamber with the amount with respect to described at least a precursor vapor, has the coating of particular physical characteristics with preparation.

24. method as claimed in claim 23, wherein the scope of the volume ratio of presoma and catalyzer is from about 1: 6 to about 6: 1.

25. method as claimed in claim 24, the scope of wherein said volume ratio are from about 1: 3 to about 3: 1.

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