pressure sensor
By forming a self-organized monolayer on the pressure-bearing surface of the pressure sensor diaphragm, the problem of reduced accuracy caused by deposits on the diaphragm was solved, and higher accuracy pressure measurement was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AZBIL CORP
- Filing Date
- 2020-06-17
- Publication Date
- 2026-05-12
AI Technical Summary
现有压力传感器在膜片上微量沉积物导致的应力无法完全消除，影响压力测定精度，尤其在高精度工艺中无法忽略。
A self-organized monolayer is formed on the pressure-bearing surface of the diaphragm of the pressure sensor, and it is made inert through chemical methods to reduce the adsorption of deposits.
It effectively reduces the impact of deposits on the membrane, improving the accuracy and reliability of pressure measurement.
Smart Images
Figure CN115597761B_ABST
Abstract
Description
[0001] This application is a divisional application of the following application.
[0002] The original application was filed on June 17, 2020.
[0003] The original application number was 202010553359.7.
[0004] The original invention application was titled: Pressure Sensor. Technical Field
[0005] This invention relates to a pressure sensor. Background Technology
[0006] For example, pressure sensors that output pressure values based on the deflection (displacement) of a diaphragm under pressure are widely used in industrial applications, primarily in semiconductor equipment. In semiconductor device manufacturing, various film deposition apparatuses based on vapor deposition and dry etching apparatuses are used. In such manufacturing apparatuses, accurate pressure measurement becomes crucial for forming thin films with a thickness of nm, requiring precise control of factors such as the pressure within the processing chamber and the partial pressure of the process gases. Pressure sensors are used to achieve this pressure measurement.
[0007] Such pressure sensors require resistance to corrosion from process gases and other gases used in the device, as well as resistance to byproducts generated during processes such as film formation. Furthermore, during the film formation process, deposits can form on the inner walls of the film-forming chamber, the inner walls of pipes, inside the vacuum pump, and on the pressure-receiving part of the pressure sensor—the diaphragm—where process gases pass through, causing various problems.
[0008] For example, atomic layer deposition (ALD) offers superior step coverage and film quality compared to the more commonly used chemical vapor deposition (CVD), and has been developed in recent years for the formation of gate insulating films. However, ALD is prone to adhering to the raw material gas at various points along its path, easily leading to the aforementioned unwanted deposits. When such unwanted deposits form on the diaphragm of a pressure sensor, they can cause zero-point shifts and changes in pressure sensitivity, as is well known, thus hindering accurate measurement and significantly impacting processing results.
[0009] To prevent the aforementioned unwanted deposition on the membrane, various parts are heated to, for example, around 200°C during the film-forming process. Furthermore, a technique has been proposed that uses baffles or similar devices to complicate the path of the process gas to the membrane, thereby capturing unwanted deposits along the way and preventing unwanted deposition on the membrane (see Patent Documents 1-3). Additionally, a technique has been proposed that the area where the process gas reaches the membrane is located at the periphery of the membrane, avoiding the center where deposition is most significant (see Patent Documents 1, 2, 4, and 5).
[0010] Furthermore, the following diaphragm structure is proposed: to address ALD, the rigidity of the diaphragm is adjusted to suppress diaphragm deflection itself (see Patent Document 6). Additionally, the following technique is proposed: to construct the diaphragm surface as a structured surface such as a lattice mesh, significantly reducing the bending stress caused by the material of the measurement medium deposited on the diaphragm (see Patent Document 7).
[0011] [Existing Technical Documents]
[0012] [Patent Documents]
[0013] [Patent Document 1] Japanese Patent Application Publication No. 2001-149946
[0014] [Patent Document 2] Japanese Patent Publication No. 2016-526153
[0015] [Patent Document 3] Japanese Patent Application Publication No. 2015-034786
[0016] [Patent Document 4] Japanese Patent Application Publication No. 2014-126504
[0017] [Patent Document 5] Japanese Patent Application Publication No. 2014-109484
[0018] [Patent Document 6] Japanese Patent Application Publication No. 2010-236949
[0019] [Patent Document 7] Japanese Patent Publication No. 2009-524024 Summary of the Invention
[0020] [The problem the invention aims to solve]
[0021] However, the increasing demand for uniform membrane thickness and quality necessitates more precise processes. Against this backdrop, the aforementioned techniques can lead to minute deposits on the membrane. Furthermore, the stress exerted by these deposits on the membrane (membrane stress) is not completely eliminated, resulting in a significant reduction in pressure measurement accuracy.
[0022] This invention was made to solve the problems mentioned above, and its purpose is to further reduce the impact of deposits on the diaphragm of the pressure sensor.
[0023] Technical means to solve the problem
[0024] The pressure sensor of the present invention comprises: a diaphragm that is displaceable and bears the pressure of a measured object on its pressure-bearing surface; and a measuring unit that measures the displacement of the diaphragm, wherein the pressure-bearing surface of the diaphragm is chemically inert by forming a self-organized monolayer.
[0025] In one embodiment of the pressure sensor described above, the self-organized monolayer is composed of multiple molecular chains with consistent orientation and end-capping atoms respectively capped on the multiple molecular chains.
[0026] According to the pressure sensor described in technical solution 1 or 2, that is, in one embodiment of the pressure sensor described above, the self-organized monolayer is composed of oriented nanotubes with consistent orientation.
[0027] In one embodiment of the pressure sensor described above, the self-organized monolayer is composed of any one of thiol-based, silane-based, or acetic acid-based compounds.
[0028] In one embodiment of the pressure sensor described above, the self-organized monolayer is positioned on a pressure-bearing surface exposed to the gas to be measured.
[0029] In one embodiment of the pressure sensor described above, the self-organized monolayer can be formed by surface treatment after the pressure sensor is fabricated.
[0030] In one embodiment of the pressure sensor described above, the self-organized monolayer can be formed by surface treatment of an already used pressure sensor.
[0031] [The effects of the invention]
[0032] Based on the above description, according to the present invention, the impact of deposits on the diaphragm of the pressure sensor can be further reduced. Attached Figure Description
[0033] Figure 1 A cross-sectional view showing the configuration of a pressure sensor according to an embodiment of the present invention.
[0034] Figure 2 A diagram illustrating the arrangement of atoms on the surface of a substance.
[0035] Figure 3 A compositional diagram showing the state in which layered material 205 is formed on the surface of a substance.
[0036] Figure 4 This is a diagram illustrating the state in which a self-organized monolayer 206 is formed on the surface of a material.
[0037] Figure 5 A cross-sectional view showing the configuration of another pressure sensor according to an embodiment of the present invention.
[0038] Figure 6 This is a top view showing a portion of the configuration of another pressure sensor according to an embodiment of the present invention.
[0039] Figure 7This is a cross-sectional view showing a portion of the configuration of another pressure sensor according to an embodiment of the present invention. Detailed Implementation
[0040] Below, for reference Figure 1 The pressure sensor according to an embodiment of the present invention will be described. This pressure sensor includes: a diaphragm 102, which is displaceable and bears the pressure of the gas to be measured on its pressure-receiving surface; and a measuring section configured to measure the displacement of the diaphragm. The measuring section of the pressure sensor includes: a movable electrode 104 formed within a movable region 102a of the diaphragm 102; and a fixed electrode 105 formed opposite to the movable electrode 104. This pressure sensor is a so-called electrostatic capacitive pressure sensor.
[0041] The diaphragm 102 is supported by a support portion 101a on a base 101 made of an insulator and is spaced apart from the base 101 within a movable region 102a. The diaphragm 102 is joined to the upper surface of the support portion 101a within a joining region 102b outside the movable region 102a. Furthermore, the diaphragm 102 is capable of displacement within the movable region 102a toward the base 101, and can withstand pressure from the object being measured.
[0042] An airtight chamber 103 is formed between the diaphragm 102 and the base 101 within the movable region 102a. A movable electrode 104 and a fixed electrode 105 are disposed inside the airtight chamber 103. As is well known, an electrostatic capacitive pressure sensor measures the pressure borne by the pressure-bearing region of the diaphragm 102 based on the change in capacitance formed between the movable electrode 104 and the fixed electrode 105. The change in capacitance formed between the movable electrode 104 and the fixed electrode 105 is converted into a pressure value and output by the measuring device 111 using a preset sensor sensitivity.
[0043] Furthermore, the pressure sensor can also be configured with a first electrode pair and a second electrode pair. The first electrode pair includes a movable electrode formed in a movable region of the diaphragm and a first fixed electrode formed opposite to the movable electrode. The second electrode pair includes a non-movable electrode formed in a non-movable region of the diaphragm and a second fixed electrode formed opposite to the non-movable electrode. This pressure sensor measures the difference between the capacitance of the first electrode pair and the capacitance of the second electrode pair.
[0044] In this pressure sensor, the pressure-receiving surface of the diaphragm 102 is chemically inert. The pressure-receiving surface of the diaphragm 102 is designed to be inert, making it difficult for it to adsorb molecules of the gas being measured, as well as gases such as residues or waste gases generated during the process. This inertness can be achieved through a prescribed surface treatment. The surface treatment forms a layer that makes the pressure-receiving surface of the diaphragm 102 inert; the presence of this layer renders the pressure-receiving surface of the diaphragm 102 inert.
[0045] Furthermore, by surface treatment, the dangling bonds of the pressure-bearing surface of the diaphragm 102 are sealed with surface-sealing molecules, thereby making the pressure-bearing surface of the diaphragm 102 inert. In this case, the diaphragm 102 is in a state where surface-sealing molecules are formed on the inert pressure-bearing surface.
[0046] It is well known that the atomic arrangement is interrupted at the surface of matter. For example, like Figure 2 As shown in (a), on the surface of a substance composed of atoms 201, the atomic arrangement is interrupted, and surface atoms 202 and dangling bonds 203 exist. The dangling bonds 203 are partially devoid of their original bonds; therefore, compared to the internal atoms 201, the surface atoms 202 are non-uniform in terms of interaction with nearby atoms or ions. Furthermore, surface atomic defects sometimes exist on the surface of the substance. For these reasons, the energy potential of surface atoms 202 differs from that of internal atoms 201; the surface atoms 202 themselves have higher energy (surface free energy), becoming an unstable (active) state.
[0047] Dangling bonds 2O3 are highly reactive and have a strong effect on phenomena such as crystal growth. Therefore, it is believed that dangling bonds 2O3 existing on the surface of materials will also promote the adsorption of nearby foreign molecules. Furthermore, such as... Figure 2 As shown in (b), the surface of a substance is reconstructed by adsorption of heterogeneous molecules 204, which constitute the gas, onto dangling bonds 203, and most of these molecules become stable. However, when the environment exposed to the surface of the substance is a vacuum or other negative pressure conditions, or when the temperature rises, the adsorbed molecules are more likely to desorb, and dangling bonds 203 will reappear on the surface of the substance, making it an active surface.
[0048] Here, it is argued that whether other atoms adsorb onto surface atoms 202 depends not only on the number of dangling bonds 203, but also on the crystal structure of the substance, the polarity of the molecules, and other factors. It is generally believed that the surface activity (the magnitude of surface potential energy) of a substance affects the adsorption of other atoms and molecules on the surface. Therefore, if the surface is inert, the adsorption of foreign matter on the surface can be prevented.
[0049] Furthermore, surface inertization of a substance can be achieved by using molecular layers composed of molecular chains terminated by fluorine or fluorine compounds that lower activation energy, connected in a direction perpendicular to the surface direction of the substance. Dangling bonds can be terminated using these molecular chains (surface-terminated molecules).
[0050] For example, through like Figure 4As shown, by depositing a self-organized monolayer 206 on the surface of a material composed of atoms 201, containing surface atoms 202 and dangling bonds 203, surface inertization can be achieved. The self-organized monolayer 206 consists of multiple molecular chains 207 with consistent orientation and end-capping atoms 208 respectively capping these molecular chains 207. Alternatively, oriented nanotubes can be used to construct the molecular chains 207. This layer is extremely thin, less than a few nm, and the surface treatment itself can be performed after the fabrication of the pressure sensor.
[0051] Self-organized monolayers include thiol-based, silane-based, and acetic acid-based monolayers. These self-organized monolayers can be formed, for example, by contacting the surface of the object being treated with a solution or vapor of reactive molecules. Self-organized monolayers can also be formed on surfaces through chemical reactions such as acid-base reactions and silane coupling reactions, using solution treatment or vapor-phase treatment.
[0052] In addition, there are carbon nanotubes (fluorine-functionalized oriented carbon nanotubes) as oriented nanotubes.
[0053] Furthermore, the surface treatment described above for achieving inertization is applied to the pressure-bearing surface of the diaphragm 102 exposed to the gas being measured, and can be performed after the pressure sensor is manufactured. Moreover, this surface treatment has no effect on the electrical output of the pressure sensor. Therefore, it is also possible to remove a pressure sensor already in use and perform the surface treatment on that sensor.
[0054] Furthermore, the pressure sensor can also be a pressure sensor equipped with a measuring unit that optically measures the displacement of the diaphragm. (Reference) Figure 5 The pressure sensor will now be described. This pressure sensor includes a base 121 and a diaphragm 122 supported on a support portion 121a of the base 121. The diaphragm 122 is movable and withstands the pressure of the gas to be measured on its pressure-bearing surface. Furthermore, the diaphragm 122 is joined to the upper surface of the support portion 121a in a joining region 122b outside the movable region 122a, and is disposed separately from the base 121 within the movable region 122a. Additionally, the base 121 is made of a light-transmitting material.
[0055] The pressure sensor's measuring unit includes a reflective membrane 124 formed within the movable region 122a of the diaphragm 122 and a semi-reflective membrane 125 formed opposite to the reflective membrane 124. It also includes a light source (not shown) emitting a first signal light and a second signal light, and an interference measuring unit (not shown). An airtight chamber 123 is formed between the diaphragm 122 and the base 121 within the movable region 122a, and the reflective membrane 124 and the semi-reflective membrane 125 are disposed inside the airtight chamber 123. The signal light emitted from the light source can be guided to the target area, for example, via an optical fiber.
[0056] In this pressure sensor, the pressure-receiving surface of the diaphragm 122 is inert. The pressure-receiving surface of the diaphragm 122 is in a state where it does not readily adsorb molecules of the gas to be measured. This inertness can be achieved through a prescribed surface treatment. By performing the surface treatment, a layer is formed that makes the pressure-receiving surface of the diaphragm 122 inert; the presence of this layer renders the pressure-receiving surface of the diaphragm 122 inert. These configurations are the same as those described in the previously presented embodiment.
[0057] The pressure sensor causes a first signal light emitted from the light source to pass through the base 121 and the semi-reflective film 125, and then be reflected on the reflective film 124 to obtain a first reflected light. Furthermore, a second signal light emitted from the light source is caused to pass through the base 121 and be reflected on the semi-reflective film 125 to obtain a second reflected light. By using an interferometer to obtain the interference between the first and second reflected lights obtained in this manner, the displacement of the diaphragm on which the reflective film 124 is provided can be measured.
[0058] Next, refer to Figure 6 , Figure 7 Another pressure sensor of the present invention will be described below. Furthermore, Figure 7 What is being shown is Figure 6 The cross-section at line xx'. This pressure sensor includes a diaphragm 159 formed on a semiconductor layer 151 and a piezoelectric element (measuring section) 150 for measuring the stress (deformation) of the diaphragm 159. By measuring the deformation of the diaphragm 159 using the piezoelectric element 150, the pressure applied to the diaphragm 159 can be measured.
[0059] Furthermore, the pressure-bearing surface of diaphragm 159, like diaphragm 102 described above, is inert. The pressure-bearing surface of diaphragm 159 does not readily adsorb molecules of the target gas. Diaphragm 159 is formed thinner than the surrounding semiconductor layer 151, and is rectangular in top view; this surface (pressure-bearing surface) is inert.
[0060] A piezoelectric element 150 is disposed on each of the four sides of a diaphragm 159. The piezoelectric element 150 includes a piezoresistive region 152, a protective region 153, contact regions 154a and 154b, and electrodes 155a and 155b. Electrodes 155a and 155b are formed on a semiconductor layer 151 through an insulating layer 156, and make ohmic contact with the contact regions 154a and 154b of the semiconductor layer 151 through the insulating layer 156.
[0061] This pressure sensor is a piezoresistive pressure sensor. By bridging the four piezoresistive regions of the four piezoelectric elements 150, the changes in resistance values of the four piezoresistive regions resulting from the deformation of the diaphragm 159 under pressure are obtained in the form of a bridge output, thereby enabling pressure measurement.
[0062] The piezoresistive region 152 is a region formed on the semiconductor layer 151 with a p-type impurity introduced therein. The semiconductor layer 151 is, for example, made of silicon. The semiconductor layer 151 is, for example, a portion of the surface side of a silicon substrate. Alternatively, the semiconductor layer 151 can also be a surface silicon layer of SOI (Silicon on Insulator), which is well known. The piezoresistive region 152 is a p-type region formed by introducing boron (B) as a p-type impurity onto the silicon semiconductor layer 151.
[0063] Furthermore, the protective region 153 is a region containing an n-type impurity formed on the semiconductor layer 151, covering the upper part of the region where the piezoresistive region 152 is formed. The piezoresistive region 152 is an n-type region formed by introducing phosphorus (p) as an n-type impurity onto the semiconductor layer 151 made of silicon. Moreover, the impurity concentration of the piezoresistive region 152 is less than the impurity concentration of the protective region 153, which is less than the impurity concentration of the contact regions 154a and 154b.
[0064] Furthermore, the protective region 153 covers the entire piezoresistive region 152 when viewed from above. The protective region 153, when viewed from above, represents the area above the piezoresistive region 152. Moreover, in the thickness direction of the semiconductor layer 151, the protective region 153 is formed on the surface side of the semiconductor layer 151 relative to the piezoresistive region 152. The protective region 153 does not need to be formed in contact with the piezoresistive region 152.
[0065] Furthermore, contact regions 154a and 154b are connected to piezoresistive region 152 and are regions containing p-type impurities formed outside the region where the protective region is formed, extending to the surface of semiconductor layer 151. Electrodes 155a and 155b are in ohmic contact with contact regions 154a and 154b on the surface side of semiconductor layer 151. Electrodes 155a and 155b are made of metals such as Au, Cu, and Al.
[0066] As explained above, according to the present invention, the pressure-bearing surface of the diaphragm is made in an inert state, thereby further reducing the impact of deposits on the diaphragm of the pressure sensor.
[0067] Furthermore, the present invention is not limited to the embodiments described above. Obviously, those with common knowledge in the art can implement a large number of modifications and combinations within the technical concept of the present invention.
[0068] Symbol Explanation
[0069] 101 Abutment
[0070] 101a Support section
[0071] 102 membrane
[0072] 102a Movable area
[0073] 103 Airtight Chamber
[0074] 104 Movable Electrode
[0075] 105 Fixed Electrode
[0076] 111 Measuring device.
Claims
1. A pressure sensor, characterized in that, have: A diaphragm, capable of displacement and bearing the pressure of the object being measured on its pressure-bearing surface; and The measuring unit measures the displacement of the diaphragm. The pressure-bearing surface of the diaphragm is chemically inert due to the formation of a self-organized monolayer.
2. The pressure sensor according to claim 1, characterized in that, The self-organized monolayer is composed of multiple molecular chains with consistent orientation and end-capping atoms respectively capping the multiple molecular chains.
3. The pressure sensor according to claim 1 or 2, characterized in that, The self-organized monolayer is composed of oriented nanotubes with consistent orientation.
4. The pressure sensor according to claim 1 or 2, characterized in that, The self-organized monolayer is composed of any one of thiol-based, silane-based, or acetic acid-based compounds.
5. The pressure sensor according to claim 1 or 2, characterized in that, The self-organized monolayer is defined as the pressure surface exposed to the gas to be measured.
6. The pressure sensor according to claim 1 or 2, characterized in that, The self-organized monolayer can be formed through surface treatment after the pressure sensor is fabricated.
7. The pressure sensor according to claim 1 or 2, characterized in that, The self-organized monolayer can be formed by surface treatment of an existing pressure sensor.