Anti-sticking layer deposition

Abstract

The invention relates to anti-sticking layer deposition. The anti-sticking layer is formed of a first organosilane precursor. A second organosilane precursor is introduced around the workpiece having the release layer. The second organosilane precursor is different from the first organosilane precursor. The second organosilane precursor is configured to eliminate defective sites and unreacted sites on the release layer and on a surface of the workpiece including the release layer.

Description

Technical Field

[0001] The present disclosure relates to films used in semiconductor manufacturing, and more particularly, termination films used in semiconductor devices. Background Art

[0002] Integrated circuit (IC) device fabrication and microelectromechanical systems (MEMS) fabrication both utilize layers of material or coatings deposited on a workpiece. In some cases, the layer is deposited on a workpiece and then subsequently removed, such as using the layer as a patterned masking material and then removing the layer after the pattern is transferred to an underlying layer. In other cases, the layer is deposited to perform a function in a device or system and remains as part of the fabricated device. There are many different methods for depositing thin film layers or coatings. In applications where wear of the coating may occur due to mechanical contact or fluid flow on the coated substrate surface, it is helpful to chemically bond the coating directly to the surface by reaction of the substance with the substrate surface in order to obtain specific surface properties.

[0003] With respect to layers and coatings that are chemically bonded to the surface of a workpiece, an area of ​​current interest is the combination of integrated circuits with mechanical systems, known as micro-electromechanical systems (MEMS). Since the dimensions of some of the electrical devices formed are nanometer-scale, and MEMS are used in applications such as biological sciences, where the type and properties of the coating on the substrate surface are utilized to provide specific functionality to the surface, there is a growing need for improved methods to control the formation of coatings or layers on the substrate surface. Historically, these types of coatings have been deposited in the liquid phase, resulting in limited control over film properties and compromised device yields due to capillary forces. More recently, vapor deposition has been used as a way to replace liquid phase processing and improve coating properties.

[0004] Pay special attention to the necessary anti-sticking layer and coating that can realize the long-term reliability of MEMS.The viscosity (bonding) of flexible micro-mechanical parts is one of the key reliability problems that have been proved to be difficult to overcome.The anti-sticking monolayer based on solution has been used routinely.But, recently, the quality, scalability and reproducibility of the film produced due to capillary viscosity, particulate problem and relatively lengthy wet treatment are unsatisfactory, therefore the vapor deposition method of anti-sticking coating is being developed diligently.Anti-sticking coating (comprising self-assembled monolayer (SAM)) is carried out vacuum treatment and vapor deposition generally obtains the higher-quality film.Integrated vapor deposition process (comprising carrying out surface plasma treatment in the same chamber) realizes better control to surface reactivity usually, avoids the possibility of sticking between micro-mechanical parts simultaneously during the anti-sticking coating coating.

[0005] Molecular vapor deposition (MVD) is a process technology that uses vapor deposition, at low temperatures, to deposit ultra-thin films on a wide range of workpieces (such as semiconductor wafers or MEMS). Compared with traditional liquid deposition techniques, the process can grow ultra-thin, functionalized organic and inorganic films with higher yields and better cost efficiency. Such films can serve as lubricity, protection, hydrophobicity, hydrophilicity, biocompatibility or reactive coatings. For example, in MEMS applications, MVD films are often used as anti-stick coatings to improve device performance and enhance the life of the entire device.

[0006] Previously, the method of forming an anti-stick coating on a silicon wafer was to dose precursor organosilane molecules individually or to dose organosilane precursors with water. In the latter case, water promotes the adsorption and polymerization of organosilane molecules. The anti-stick coating formed is usually a SAM film.

[0007] Some anti-adhesive coatings can grow in multiple modes. Some polymerization reactions produce polymers similar to polydimethylsiloxane (similar to PDMS), and they are terminated by hydroxyl groups. These hydroxyl groups can cause viscous forces due to reducing the hydrophobicity of the coating and exposing the OH groups, and are therefore harmful to certain applications, such as anti-adhesive. The current anti-adhesive films currently used are perfluorodecyl trichlorosilane (FDTS) and fluorooctyl trichlorosilane (FOTS) coatings. However, these films contain fluorine, which is not desirable due to environmental issues.

[0008] Therefore, there is a need for improved techniques to improve release coatings. Summary of the invention

[0009] In a first embodiment, a deposition method is provided. A first layer is deposited on a workpiece. The first layer is formed from a first organosilane precursor and can be a release layer. A second organosilane precursor is introduced around the workpiece having the first layer. The second organosilane precursor is different from the first organosilane precursor. The second organosilane precursor is configured to eliminate defect sites and unreacted sites on the first layer and on the surface of the workpiece including the first layer.

[0010] The first layer may be deposited using a vapor deposition method.

[0011] The method may include depositing a second organosilane precursor on the first layer using a vapor deposition method.

[0012] The first organosilane precursor may be dimethyldichlorosilane or dimethyldiethoxysilane. In one example, the second organosilane precursor is N,N-dimethyltrimethylsilylamine or trimethylchlorosilane.

[0013] The first layer may be a self-assembled monolayer.

[0014] The workpiece can be silicon or aluminum oxide.

[0015] The defect site may be a hydroxyl group.

[0016] The method may include performing a purge process using an inert gas between depositing the first layer and introducing the second organosilane precursor.

[0017] The second organosilane precursor may have at least the same chain length as the first organosilane precursor.

[0018] In a second embodiment, a device is provided. The device includes a workpiece, a first layer disposed on the workpiece, and a second layer disposed on the first layer. The first layer is formed from a first organosilane precursor and can be an anti-sticking layer. The second layer is formed from a second organosilane precursor. The second organosilane precursor is different from the first organosilane precursor. The second organosilane precursor is configured to eliminate defect sites and unreacted sites on the first layer and on the surface of the workpiece including the first layer.

[0019] The workpiece can be silicon or aluminum oxide.

[0020] The first organosilane precursor may be dimethyldichlorosilane or dimethyldiethoxysilane. In one example, the second organosilane precursor is N,N-dimethyltrimethylsilylamine or trimethylchlorosilane.

[0021] The first layer may be a self-assembled monolayer.

[0022] The second organosilane precursor may have at least the same chain length as the first organosilane precursor.

[0023] The defect site may be a hydroxyl group.

[0024] The workpiece may be part of a MEMS device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a fuller understanding of the nature and objects of the present disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 A method according to the present disclosure is illustrated using a series of cross-sectional views;

[0027] Figure 2 showing a PDMS-like polymer having hydroxyl groups; and

[0028] Figure 3 Shows the elimination of hydroxyl groups using different organosilane molecules. DETAILED DESCRIPTION

[0029] Although the claimed subject matter will be described in terms of certain embodiments, other embodiments (including embodiments that do not provide all of the benefits and features set forth herein) are also within the scope of the present disclosure. Various structural, logical, method step, and electronic changes may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is limited only by reference to the appended claims.

[0030] Embodiments disclosed herein can improve the anti-stick properties of SAM or other anti-stick coatings by eliminating defect sites. In embodiments disclosed herein, a first layer is deposited on a workpiece. The first layer may contain defect sites, such as hydroxyl groups. A second layer is then deposited on the first layer, thereby eliminating the defect sites. A second precursor is then introduced, which preferentially reacts with and removes the defect sites. Thus, defects in the thin layer formed by the first precursor are repaired. Two different organosilane molecules can be used to form an improved anti-stick coating.

[0031] Figure 1 A method is illustrated using a series of cross-sectional views. In step A, a workpiece 100 is provided. The workpiece 100 may be a semiconductor wafer or a MEMS device. For example, the workpiece 100 may be silicon or aluminum oxide.

[0032] In step B, a first layer 101 is deposited on the workpiece 100. The deposition is performed using MVD, another vapor deposition technique, a liquid phase chemical process, or another deposition technique. A first organosilane precursor 103 is used during the deposition. The first organosilane precursor 103 may be introduced around the workpiece 100 along with water. The deposition of the first layer may be performed at a temperature of 20° C. to 150° C. In one example, the dosage of the first organosilane precursor 103 may be 0.5 to 2 Torr and the water dosage may be 0.5 to 4 Torr.

[0033] In one example, the first organosilane precursor 103 and water vapor are maintained in the MVD chamber for about 1 to 60 minutes. For example, a period of about 15 minutes may be used. In order to obtain better film quality, multiple reaction cycles with the first organosilane precursor 103 may be required. In one example, 1 to 10 reaction cycles are performed.

[0034] MVD is a gas phase reaction between a surface reactive chemical and a surface suitable for receiving (such as the surface of the workpiece 100). Difunctional silanes can be used, in which one end of the molecule is reactive. The advantage of gas phase reactions over comparable liquid phase processes is the control of ambient moisture, which often causes cross polymerization of silanes, resulting in the generation of particles on the treated surface. A heated, sub-atmospheric vacuum chamber is typically used to achieve precise control of reactants and water content. In addition, gas phase processes allow for the processing of complex parts because the coverage of the reactants is typically limited by diffusion. With respect to surface-to-surface interactions, MEMS sensors can be used to address stiction and other parasitic issues. An example of an MVD system is shown in U.S. Publication No. 2013 / 0312663, which is incorporated by reference in its entirety.

[0035] Step C shows a workpiece 100, wherein the resulting first layer 101 is formed from a first organosilane precursor 103. The first layer 101 can be a single layer or a multilayer. In one example, the first layer 101 is a self-assembled monolayer. In one example, the first layer 101 can be an anti-sticking layer. There may be defects on the first layer 101, which may include hydroxyl groups. Based on the crystal structure of SiO2, there may be less than 13 defects / nm 2 Other numbers or frequencies of defects may exist.

[0036] Although hydroxyl groups are specifically disclosed, other defects may form and can be addressed using the embodiments disclosed herein. For example, a defect may be chlorine, which may be sealed by an amino group such that the reaction byproduct is HCl. Aldehydes may react with amines, where H2O is a byproduct. Other OH and NH groups may form defects and may react using the techniques disclosed herein.

[0037] The thickness of the resulting first layer 101 may be about 0.2 nm to 10 nm for a silicon workpiece, and may be about 0.2 nm to 100 nm for an aluminum workpiece. In one example, the thickness of the resulting first layer 101 is about 1 nm.

[0038] In step D, a second organosilane precursor 104 is introduced around the workpiece 100 having the first layer 101. The second organosilane 104 may be deposited with or without other substances. The second organosilane 104 may be the only substance necessary to eliminate defect sites. The second organosilane precursor 104 is different from the first organosilane precursor 103. For example, the second organosilane precursor 104 may be deposited on the workpiece 100 using MVD. The temperature during the deposition of the second organosilane precursor 104 may be 20° C. to 150° C. The pressure during the deposition of the second organosilane precursor 104 may be 0.1 torr to 5 torr.

[0039] In one example, the second organosilane precursor 104 is injected into the MVD chamber to be deposited on the first layer 100. The reaction time can be about 30 seconds to 2 hours. For example, the reaction time can be about 15 minutes. The unreacted second organosilane precursor 104 can be pumped out at the end of step D.

[0040] In step E, a second layer 102 formed of a second organosilane precursor 104 is formed on the first layer 101. The second organosilane precursor 104 is configured to eliminate defect sites on the first layer 101. The second organosilane precursor 104 is different from the first organosilane precursor 103. The second organosilane precursor 104 repairs the original structure of the first layer 101 by reacting with hydroxyl groups. The silane functional groups in the second organosilane precursor 104 can react with the hydroxyl groups in the first layer 101 to form Si-O bonds on the surface of the first layer 101 and release dimethylamine, which can then be pumped out of the chamber. This improves the anti-sticking properties of the resulting device due to the elimination of defect sites.

[0041] In addition to eliminating defect sites on the first layer 101, defect sites on the surface of the workpiece 100 may also be eliminated. This surface may be the same surface of the workpiece 100 including the first layer 101. For example, after forming the first layer 101, a portion of the workpiece 100 may be exposed.

[0042] The precursor of the first layer 101 is usually small, but such a precursor can be polymerized to form a longer chain. In the case where the molecular length is the same as or shorter than the first organosilane precursor 103, the second organosilane precursor 104 can penetrate the first layer 101 to a certain extent. However, the second organosilane precursor 104 can also have the same or longer length as the first organosilane precursor 103. The length or reactivity of the second organosilane precursor 104 can be selected so that it can react with the remaining OH groups, unreacted sites or defect sites.

[0043] Although for simplicity in Figure 1 101, but the second organosilane 104 is selectively adsorbed on the defect points in the first layer 101. If there are no defects on the first layer 101, the second layer 102 is not formed. The total number of defects after adding the second organosilane precursor 104 can be <<13 / nm 2 .

[0044] The second layer 102 may be formed from a monofunctional precursor. As a monofunctional compound, the second organosilane precursor 104 tends not to introduce any additional defect sites. In contrast, during the film-forming reaction, difunctional or trifunctional chemicals may generate additional OH groups. The monofunctional compound may sweep and react with any existing defect sites, thereby eliminating them.

[0045] The reactivity, dosage and size of the second organosilane precursor 104 molecules can be configured to optimize the elimination of defects. The functional group can be directly related to the chemical reactivity. The reactivity of the aminosilane functional group is generally greater than that of the chlorosilane and alkoxysilane functional groups. Due to thermodynamics, higher temperatures and larger doses can also enhance reactivity. The small size of the second organosilane precursor 104 molecules means that the molecules can penetrate the voids and vacancies of the first layer 101, which is a geometric effect.

[0046] In one example, the first organosilane precursor 103 is dimethyldichlorosilane (DDMS) or dimethyldiethoxysilane. Other examples of the first organosilane precursor 103 may include other vapor deposition polymers, such as bis(N,N-dimethylamino)dimethylsilane, dimethyldimethoxysilane, diethoxydimethylsilane, or 1,3-dichloro-1,1,3,3-tetramethyldisiloxane. Mixtures of these precursors are also possible. The first organosilane precursor 103 may also be an organosilane monomer having two reactive functional groups that can be polymerized to form a polymer chain.

[0047] In one example, the second organosilane precursor 104 is N,N-dimethyltrimethylsilylamine (TMSDMA) or trimethylchlorosilane (TMCS). As the second organosilane precursor 104, other organosilanes may be used, such as N,N-diethyltrimethylsilylamine (TMSDEA), methoxytrimethylsilane (TMSOMe), ethoxytrimethylsilane (TMSOEt), trimethylsilyl trifluoromethanesulfonate (TMSOTf) or trimethylsilyl fluorosulfonate (TMSOFs). Mixtures of these precursors are also possible. The second organosilane precursor 104 may be selected to avoid certain reaction byproducts, such as HCl or dimethylamine. In one example, the second organosilane precursor 104 may be a monofunctional silane.

[0048] In one example, the second organosilane precursor 104 can have at least the same chain length as the first organosilane precursor 103 .

[0049] In one example, a purge process is performed between the introduction of the first organosilane precursor 103 and the introduction of the second organosilane precursor 104 or between cycles of introducing the first organosilane precursor 103. The purge process may use an inert gas such as N2 or Ar, thereby purging unreacted precursor gas and reaction byproducts.

[0050] The resulting device includes a workpiece 100, a first layer 101, and a second layer 102. The first layer 101 may be an anti-adhesion layer. The second layer 102 may eliminate defect sites (eg, hydroxyl groups) on the first layer 101. The first layer 101 and the second layer 102 may be anti-adhesion films.

[0051] In one embodiment, Figure 1 The method can be used for MEMS anti-adhesion film. Figure 1 The layers formed by the method may be beneficial because the layers do not contain fluorine. Fluorine-containing materials are generally undesirable for environmental reasons.

[0052] Combination Figures 2 to 3 Explain this method further. Figure 2 A PDMS-like polymer with hydroxyl groups is shown. Figure 3 Shows the elimination of hydroxyl groups using different organosilane molecules. Figure 2 The hydroxyl groups in are unreacted sites. Figure 3 As shown in , the organosilane molecules react with the hydroxyl groups and eliminate the defects.

[0053] Unreacted sites are any chemical groups that can react with the organosilane precursor. Most unreacted sites in anti-sticking applications are OH groups. For example, unreacted sites can be any remaining OH groups on the surface. They can be OH groups that were originally present on the surface and still exist because they did not react with the first organosilane precursor.

[0054] During the reaction of the first organosilane precursor, defect sites such as OH groups may be formed. Defect sites are subsequently formed during the coating of the first layer and such defect sites are not initially present on the sample surface.

[0055] In the experiment, the stiction force was measured by atomic force microscopy (AFM). The capped DDMS coating has pendant hydroxyl groups that need to be passivated. TMSDMA molecules can react with the hydroxyl groups and passivate the DDMS film. An AFM silicon tip was placed in contact with the MVD coated surface to simulate the stiction force and measure the anti-stick properties of the coating.

[0056] AFM was performed in tapping mode and force volume mode. 1×1 μm scans were collected using a resolution of 512×512 pixels. 16×16 point adhesion maps were collected over a 50×50 μm area. TMSDMA-terminated DDMS coatings exhibited lower adhesion than DDMS-only coatings, as shown in the table below.

[0057] Roughness Sa(nm) Average bonding force (nN) STDev Adhesion(nN) DDMS coated Si 0.126 45.49 2.29 TMSDMA-terminated DDMS on Si 0.15 6.37 0.47

[0058] Although the present disclosure has been described in conjunction with one or more specific embodiments, it should be understood that other embodiments of the present disclosure can be formed without departing from the scope of the present disclosure. Therefore, the present disclosure is considered to be limited only by the appended claims and reasonable interpretations thereof.

Claims

1. A deposition method, comprising: depositing a first layer on a workpiece, wherein the first layer is formed from a first organosilane precursor, and wherein the first layer is a release layer; and A second organosilane precursor is introduced around the workpiece having the first layer, wherein the second organosilane precursor is different from the first organosilane precursor, and wherein the second organosilane precursor is configured to eliminate defect sites and unreacted sites on the first layer and on a surface of the workpiece including the first layer. The deposition method according to claim 1 , wherein the first layer is deposited by vapor deposition. 3 . The deposition method according to claim 1 , further comprising depositing the second organosilane precursor on the first layer by vapor deposition. The deposition method according to claim 1 , wherein the first organosilane precursor is dimethyldichlorosilane or dimethyldiethoxysilane. The deposition method according to claim 4 , wherein the second organosilane precursor is N,N-dimethyltrimethylsilylamine. The deposition method according to claim 4 , wherein the second organosilane precursor is trimethylchlorosilane. The deposition method of claim 1 , wherein the first layer is a self-assembled monolayer. The deposition method according to claim 1 , wherein the workpiece is silicon or aluminum oxide.

9. The deposition method of claim 1, wherein the defect site is a hydroxyl group. 10 . The deposition method of claim 1 , further comprising performing a purge process using an inert gas between depositing the first layer and introducing the second organosilane precursor. 11 . The deposition method of claim 1 , wherein the second organosilane precursor has at least the same chain length as the first organosilane precursor.

12. A device comprising: Workpieces; a first layer disposed on the workpiece, wherein the first layer is formed from a first organosilane precursor, and wherein the first layer is a release layer; and a second layer disposed on the first layer, wherein the second layer is formed from a second organosilane precursor, wherein the second organosilane precursor is different from the first organosilane precursor, and wherein the second organosilane precursor is configured to eliminate defect sites and unreacted sites on the first layer and on a surface of the workpiece including the first layer.

13. The device of claim 12, wherein the workpiece is silicon or aluminum oxide.

14. The device of claim 12, wherein the first organosilane precursor is dimethyldichlorosilane or dimethyldiethoxysilane.

15. The device of claim 14, wherein the second organosilane precursor is N,N-dimethyltrimethylsilylamine.

16. The device of claim 14, wherein the second organosilane precursor is trimethylchlorosilane.

17. The device of claim 12, wherein the first layer is a self-assembled monolayer.

18. The device of claim 12, wherein the second organosilane precursor has at least the same chain length as the first organosilane precursor.

19. The device of claim 12, wherein the defect site is a hydroxyl group.

20. The device of claim 12, wherein the workpiece is part of a MEMS device.

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