TWI772814B - Method and apparatus for silicon based charge neutralization - Google Patents

Abstract

An embodiment of the invention provides a method for low emission charge neutralization, comprising: generating a high frequency alternating current (AC) voltage; transmitting the high frequency AC voltage to at least one non-metallic emitter; wherein the at least one non-metallic emitter comprises at least 70% silicon by weight and less than 99.99% silicon by weight; wherein the at least one emitter comprises at least one treated surface section with a destroyed oxidation layer; and generating ions from the at least one non-metallic emitter in response to the high frequency AC voltage. Another embodiment of the invention provides an apparatus for low emission charge neutralization wherein the apparatus can perform the above-described operations.

Description

Silicon-based charge neutralization method and device

Embodiments of the present invention are primarily concerned with ionization devices for electrostatic charge neutralization and control. More specifically, embodiments of the present invention address the need for reliable and low particle emission ionizers within the semiconductor, electronics, and/or flat panel industries.

With an AC ionizer, each emitter receives a high positive voltage during one time period and a high negative voltage during another time period. Therefore, each emitter generates corona discharge without outputting both positive and negative ions.

Positive and negative ion streams (clouds) are directed towards the charged target for the purpose of neutralizing the charge and preventing static electricity associated with technical problems.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. The creations currently referred to as inventors, the creations described in this background section, and aspects of the description that may not be sufficient at the time of filing to claim prior art are not expressly or implicitly admitted as objections to this disclosure of prior art.

The ion emitter of the charge neutralizer generates and supplies both positive and negative ions into the surrounding air or gaseous medium. In order to generate gas ions, the amplitude of the applied voltage must be high enough to generate a corona discharge between at least two electrodes configured as ionization cells. In the ionization cell, at least one electrode is an ion emitter, and the other electrode can be a reference electrode. It is also possible that the ionization unit comprises at least two ionization electrodes.

Along with the useful positive and negative gas ions, the emitter of the charge neutralizer may produce and emit corona by-products, including undesired particles. In semiconductor processing and similar cleaning processes, particle emission/contamination is associated with defects, product reliability issues, and lost profits.

Several factors are known in the art to affect the amount of undesired particle emission. Some primary factors include, for example, the material composition, geometry, and design of the ion emitter. The second factor includes the configuration of the emitter connection to the high voltage power supply. Another key factor is related to the profile of the power applied to the ion emitter (magnitude and time dependence of high voltage and current).

The power waveform can be used to control the voltage profile of the high voltage power supply to the emitter. The voltage/current waveform can be used to control both ion production and particle emission from the emitter.

Corona discharges can be excited by direct current (DC) voltage, alternating current (AC) voltage, or a combination of both. For many applications of the present invention, the preferred power waveform is a high frequency high voltage (HF-HV) output from a high frequency (HF) power supply, as will be discussed below. This high voltage output may be continuous rather than continuous. That is, the voltage output may be variable amplitude in time or periodically turned off.

The material composition of the emitter is known to affect the degree of particle emission from the ionizer. Common emitter materials include stainless steel, tungsten, titanium, silicon oxide, single crystal silicon, silicon carbide, and other metals plated with nickel or gold. This list is not complete. It is known from the inventors' experience that metallic emitters tend to generate more particles because of corona associated with erosion and sputtering. Additionally, metals (or, in general, highly conductive particles) are often considered "killer particles" in the semiconductor industry (ie, these particles can be short-circuited and tightly positioned on the conductive traces of the wafer/chip). Therefore, in the framework of this patent application, the inventors basically consider non-metallic ion emitters, as will be discussed below.

One of these materials, proposed by Scott Gehlke in US Pat. No. 5,447,763, is ultra-clean (over 99.99% pure) single crystal silicon from a low particle emission standpoint. This single crystal silicon has been adopted by the semiconductor industry as a practically clean emitter standard. Curtis et al. in US Patent Application Publication No. 2006/0071599 suggest that ultra-clean silicon carbide (at least 99.99% pure) is another non-metallic material. However, silicon carbide emitters are expensive and tend to emit unwanted particles.

Known ionizers with monocrystalline silicon emitters are powered by two high voltage DC supplies. A system for cleanroom ceiling installations (such as the cleanroom ionization system "NiLstat 5000" (Ion Systems, Inc.) typically produces less than 60 particles (larger than 10 in diameter) per cubic foot of air. nanometers). Other emitter materials typically produce more than 200 particles per cubic foot of air (greater than 10 nanometers in diameter). Some materials produce thousands of particles (greater than 10 nanometers in diameter) per cubic foot of air.

While either (1) the composition of the emitter material, (2) the components of the non-metallic emitter connector construction, and (3) the application of a particular power waveform are known to be independently important, the prior art has not Consider the benefits of strategically combining these factors to achieve high ionization reliability and cleanliness.

Recent experiments by the inventors have led the inventors to discover and find novel combinations of stable ion production at the emitter with unpredictable particle production at low levels. Clean and/or low particle emission ionizers have utility in many high-tech industries. Specifically, the semiconductor industry has a well-defined need for ultra-clean ionizers. Ionizers are required to minimize static and electric fields that can damage semiconductor devices. There is also a need for particle emission as low as possible, since foreign particles can compromise the reliability of semiconductor devices. The Advanced Semiconductor Technology Department builds 24-16nm features on wafers. For nanometer features, there is an absolute need for control over particles larger than 10 nanometers.

It is to be understood that the foregoing general description in the Background section is exemplary and explanatory only and does not limit the invention as claimed.

Recent experiments by the inventors have shown that: (1) the composition of the silicon-based material and the design of the emitter, (2) the configuration and/or construction of the emitter connector, and (3) the type of supply voltage waveform that should be considered an emitter Synthetic, novel and advantageous combination of extremely reliable performance and low particle emission. The combination found by the inventors can result in stable ion production at the emitter with unpredictable particle production at low levels. Clean and/or low particle emission ionizers have utility in many high-tech industries. Specifically, the semiconductor industry has a well-defined need for ultra-clean ionizers. Ionizers are required to minimize static and electric fields that can damage semiconductor devices. There is also a need for particle emission as low as possible, since foreign particles can compromise the reliability of semiconductor devices. The Advanced Semiconductor Technology Department builds 24-16nm features on wafers. For nanometer features, there is an absolute need for control over particles larger than 10 nanometers.

Emitter electrode compositions including silicon-based materials, electrode connectors, and matching of power waveforms applied to the emitters have proven to be novel approaches to achieve a level of reliability and cleanliness previously unattainable with charge neutralizing ionizers. Exemplary embodiments of the present invention are at the heart of the combination of a non-metal ion emitter of silicon with a material/chemical weight percentage ranging from less than 99.99% to at least 70%, an emitter electrode design, and a surface treatment ( preparation), the connection configuration of the emitter, and the high voltage power supply operating in the high frequency range. In this combination, the high frequency high voltage power supply produces a corona discharge mode characterized by a low onset voltage. In an embodiment of the present invention, the ions generated from the at least one non-metallic emitter include positive ions and negative ions generated with a minimum starting HF voltage and power supply.

This combination is valid and suitable for many different types of cleanroom ionizers/charge neutralizers. As an example, the ionizers of embodiments of the present invention may be considered as embedded ionizers targeted for use in a Class 1 clean room production environment. The ionizer can have an incoming flow of clean dry air (CDA) or nitrogen, argon, or other inert gas. The gas or air passes along the silicon-based emitter inside the ionization cell. The ionization cell/chamber is usually closed except for air/gas inlet and outlet openings.

The design of embedded charge neutralization ionizers according to embodiments of the present invention may use compact power supplies such as high frequency high voltage supplies. The output connector of the power supply accommodates at least one silicon-based emitter. The ionization unit produces clean bipolar ionization. Air flow (or nitrogen or argon flow or other gas flow) is sufficient to move ions from the ionizing emitter (cell or chamber) to the charge neutralizing target.

The high frequency voltage curve of the power supply has an AC frequency range of approximately 1KHz to 100kHz. The peak voltage exceeds the corona onset voltage (positive and negative) of the emitter. The ionic current of the emitter of high frequency AC is substantially limited by the resistance value of the silicon-based material.

In this current application, high voltage is defined as the potential difference between at least one ion generating electrode and a reference electrode. In some high frequency AC ionization cells, the reference electrode may be isolated from the ionization electrode by a dielectric wall. Therefore, the possibility of direct electron, ion collapse (like a spark discharge) between electrodes is practically excluded, and particle emission from the emitter can be greatly reduced. During the operating mode, ions are generated whenever the voltage amplitude exceeds the positive and negative corona initiation voltages applied to the ionization electrodes.

When the high frequency AC voltage curve is periodic rather than continuous, another frequency (selective) becomes relevant. That is, only for a predetermined time interval, a high frequency AC voltage that exceeds the starting voltage curve is generated. In this scheme, a high frequency AC voltage is applied to the emitter during the enable time interval (typically about 0.01 seconds (or less) to about 1 or more seconds), but may be applied lower than the enable time during the non-enable time interval starting voltage. This selective high frequency voltage waveform may also substantially include an on/off high voltage mode. The normal low voltage or on/off frequency range is approximately 0.1 Hz to 500 Hz, but the frequency can be outside this range.

Some silicon-containing emitter compositions are provided as examples. They are: (a) doped crystalline silicon, (b) doped polysilicon, (c) a combination of doped silicon and silicon oxide, and (d) deposited on a silicon-doped substrate. The main purpose of dopants and additives is to control the surface and volume resistivity, as well as the mechanical properties of silicon-based emitters. They are preferably taken from the known group of non-metallic dopants, such as boron, arsenic, carbon, phosphorus, and others.

Accordingly, at least one exemplary embodiment of the present invention provides a method for low emission charge neutralization, the method comprising the steps of: generating a high frequency alternating current (AC) voltage; delivering the high frequency AC voltage to at least one non-metallic emitter electrode; wherein at least one non-metallic emitter includes at least 70% by weight of silicon and less than 99.99% by weight of silicon; wherein at least one non-metallic emitter includes at least one treated surface portion, and at least one treated surface portion has destroying the oxide layer; and generating ions from at least one non-metallic emitter in response to a high frequency AC voltage.

At least one exemplary embodiment of the present invention also provides an apparatus including elements that allow the above-described functionality. For example, embodiments of the present invention provide an apparatus for low emission charge neutralization, comprising: at least one non-metallic emitter comprising at least 70 wt% silicon and less than 99.99 wt% silicon ; wherein at least one non-metallic emitter includes at least one treated surface portion, at least one treated surface portion has a damaged silicon oxide layer; and wherein at least one non-metallic emitter generates ions in response to a high frequency AC voltage.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment(s) of the invention, and together with the description serve to explain the principles of the invention.

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various embodiments of the present invention. Those skilled in the art will appreciate that these various embodiments of the present invention are illustrative only and are not intended to be limiting in any way. Other embodiments of the present invention will readily occur to those skilled in the art having the benefit of this disclosure to contemplate such embodiments.

Furthermore, in the interest of clarity, not all of the conventional features of the embodiments described herein are shown or described. Those skilled in the art will readily appreciate that in the development of any such actual implementation, many implementation-specific decisions may be required to achieve specific design goals. These design goals will vary from implementation to implementation and from developer to developer. Furthermore, it will be appreciated that such a development effort may be complex and time-consuming, but nonetheless a general engineering undertaking given to those skilled in the art having the benefit of this disclosure. The various embodiments disclosed herein are not intended to limit the scope and spirit of the disclosure herein.

Exemplary embodiments for implementing the principles of the invention will be described herein with reference to the drawings. However, the present invention is not limited to the specifically described and illustrated embodiments. Those skilled in the art will appreciate that many other embodiments are possible without departing from the basic concept of the present invention. Accordingly, the principles of the present invention extend to any article of manufacture falling within the scope of the appended claims.

As used herein, the term "a" herein does not denote a limitation of quantity, but rather denotes the presence of at least one of the referenced item.

Experimentally, it has been demonstrated by the inventors that, for example, an electrically balanced ionic gas flow with very few particles can be reliably generated by combining the following embedded ionizers: (1) an emitter containing silicon (2) a configuration As a pin-type electrode contacting a conductive socket, and (3) capacitively receiving a high frequency AC voltage waveform. The level of reliability and cleanliness of the ionization produced by the above combination cannot be achieved individually with non-metallic silicon-containing emitters or high frequency AC voltage waveforms known in the art. Accumulated particles greater than or equal to 10 nm in diameter were measured during the cleanliness test. Particle counters (like CNC (condense particle counter) - condensed particle counters) do not divide particles into size ranges.

For example, two single crystal silicon emitters for a clean room ionization system (eg, NiLstat ionization system) (similar to system 200 shown in Figure 2) for connection to a DC or pulsed DC (+/-20kV) power supply (discussed in US Patent No. 5,447,763) produces approximately 60 particles (greater than 10 nanometers in diameter) per cubic foot of air. In contrast, ionizers disclosed in embodiments of the present invention produce less than 10 nanoparticles of the same diameter per cubic foot of air. From a stereoscopic perspective, 10 particles larger than 10 nanometers per cubic foot of air are nominally 6 times cleaner than the cleanest prior art ionizer at this time in this application.

In the opposite example, a metal emitter (tungsten) was tested with a conventional system (eg, the system in US Pat. No. 5,447,763) and exhibited unacceptable numbers of clean room particle emissions. Our experiments using a tungsten emitter combined with a high frequency AC high voltage waveform (similar to that presented in US Patent Application Publication No. 2003/0007307 (Lee et al.)) had little benefit in cleanliness, compared to As with the conventional system previously disclosed in US Pat. No. 5,447,763. The particle concentration totals for the tested tungsten emitters in both instances resulted in over 600 particles per cubic foot of air (greater than 10 nanometers).

However, high-purity (99.99% or higher) single-crystal silicon emitters (such as those shown in Figure 1(a), Figure 1(b), and Figure 1(c)) have high resistance value (in the megohm range). When this emitter is connected to a high frequency (HF) AC voltage supply, generally, the generation of ions is not sufficient for efficient charge neutralization. The main reason is because most of the HF (high frequency) current/voltage goes into the stray capacitors and not to the emitter tip.

Another problem associated with high-purity (above 99.99% pure) single-crystal silicon emitters is that the emitter is prone to a surface oxide "skin" (in Figure 1(c), the surface surrounding the silicon emitter 101c) , the oxide layer or skin layer depicted by dashed line 102c). The skin/layer 102c includes highly insulating silicon oxide (SiO ₂ ). For example, in the following Stanford University publication in California ("Growth of native oxide, 28 August 2003 Stanford University Nanofabrication Facility, 28 August 2003) ") discusses the growth of silicon oxide on the surface of clean silicon wafers.

The end result of the silicon oxide layer growth phenomenon is that the non-metallic silicon emitter/pin is surrounded by this insulating layer and does not have a good, reliable connection to the electrical socket (and thus the high voltage output of the HF power supply).

Another non-metal ion emitter is discussed in US Patent Application Publication No. 2006/0071599 to Curtis et al. This emitter is made of high-purity 99.99% silicon carbide. This material is a synthetic material with approximately 30% carbon. It is known in the art that silicon carbide has a high hardness. Silicon carbide is also expensive to manufacture as pin-type emitter structures. In addition, silicon carbide has high electrical conductivity of the metallic type. Conductive particles from synthetic materials with high carbon content are generally undesirable in the semiconductor industry.

Wide acceptance of silicon materials in the semiconductor industry requires lower cost of ion emitter materials. In addition, the mechanical properties of silicon-based materials allow for easy processing (cutting, polishing, etc.). The primary goal of a small concentration of silicon dopants and additives is to control surface and volume resistivity, and to improve the mechanical properties of silicon-based emitters. They are preferably taken from the known group of non-metallic dopants, such as boron, arsenic, carbon, phosphorus, and others.

In an embodiment of the present invention, an emitter having a silicon-based composition with a silicon content of less than 99.99% and more than 70% by weight can achieve a resistance value in the kiloohm range. This resistance value is low enough to conduct high frequency current and support stable corona discharge. Therefore, two specific factors interact harmoniously to produce the observed cleanliness improvement: the composition and design of the silicon-based emitter, and the high frequency AC emitter drive power/voltage waveform.

One advantage of the combination of silicon-based emitters and HF voltage waveforms is that the onset voltage of corona discharges (approximately 1,000V to 3,000V or higher) is significantly lower than the DC, pulsed DC, or low frequency used for non-metallic emitters (50Hz to 60Hz) voltage of corona discharge initiation voltage.

A possible explanation for this effect is that in the high frequency range (approximately 1 kHz to 100 kHz or higher), the voltage applied to the emitter changes polarity in the range of milliseconds or microseconds. This is why the corona charge carriers (positive and negative ions, electrons) do not have enough time to move away from the emitter tip. In addition, the specific surface charge conservation (often named "charge memory") properties of silicon-based materials can play a role in electron emission at the electrode surface. This is why both positive and negative high frequency corona onset voltages are low. With the lower voltage of the HF corona discharge, the particle emission from the silicon-based emitter will also be less.

The scientific basis for the improvement of particle emission from corona discharges of balanced ionizers due to the interaction between non-metallic silicon-based emitters and high frequency AC voltage waveforms is currently under investigation. The accepted theory of corona discharge and/or ionization and/or particle emission from non-metallic emitters does not predict or fully explain the observed experimental cleanliness.

However, it is clearly understood how to make and use the present invention. The following description is written to explain how those skilled in the art of static control can make and use the present invention.

Experimental preparations for embodiments of the present invention, including combinations of silicon-based emitter compositions and HF voltage waveforms, demonstrate that, in some cases, ionizers with brand new or long idle emitters exhibit activation The problem of initiating HF corona discharge and generating ions reliably. Measurements showed high contact resistance values between the silicon emitter and the electrical socket. This high resistance value is one cause of corona initiation problems with ionization devices. Process formation of thicker (10 ^th to 100 ^th angstrom or more) oxide "skin layers" on silicon wafers in open air is documented in the above cited reference ("Growth of native oxides"). oxide), at the Stanford University Nanofabrication Facility”). For example, over a six-day period, the _SiO2 surface layer can reach a thickness of 12 angstroms. Silicon oxide is known to be a good insulator. Therefore, this skin layer growth results in higher surface and contact resistance values for silicon-based emitters. The rate of oxide growth is variable and is related to many surrounding atmospheric factors, such as oxygen and ozone concentrations (see web link http://iopscience.iop.org/0953-8984/21/18/183001/pdf /cm9_18_183001.pdf "Silicon oxidation by ozone"), temperature, humidity, etc. Ozone is one of the by-products of corona discharge and may accelerate the oxidation of silicon emitters. This phenomenon has a profound effect on the lower supply voltage of HF ionizers with silicon-based non-metallic emitters. Exemplary embodiments of the present invention include surface treatment of the silicon-based emitter to reduce the contact resistance value between the emitter and the metal socket.

Figure 1(a) is an illustration of a conventional silicon emitter 100a. Emitter 100a includes four distinct parts: tip 101a, taper 102a, shaft 103a, and tail 104a. The shape and size of the tip 101a depends on the availability of high voltage and current from a high voltage power supply (HVPS), the material of the emitter, and the technique and method of production. The emitter tip 101a is generally the most critical part of any ion emitter. The emitter tip 101a is directly exposed to the corona discharge and determines the lifetime length of the emitter. The silicon emitter has a generally cylindrical shaft portion 103a. The shaft portion 103a mainly defines the length of the emitter and the distance between the cone portion and the socket or container connected to the high voltage power supply. The taper or cone 102a is the transition between the tip 101a and the shaft 103a. Silicon is an inherently brittle material, and the taper angle is a compromise between the mechanical strength and electrical properties of the emitter. The tail portion 104a may be rounded, beveled, or chamfered. This part should assist in inserting the emitter 100a into the socket or container. Standard high-purity silicon emitters have a smooth surface due to chemical polishing, which is usually achieved by a strong acid treatment.

Figure 1(b) shows an illustration of a silicon emitter with a metal sleeve. The silicon emitter 100a includes a non-metallic silicon portion 101b and a stainless steel tube 102b (or a sleeve 102b), and the sleeve 102b has a recess 105b. The sleeve 102b should protect the brittle silicon emitter 101a from mechanical (handling) damage. The sleeve 102b should also improve the electrical connection of the non-metal high purity silicon emitter to the metal socket or container. Views 103b and 104b illustrate the assembly of the silicon emitter 100a and the metal sleeve 102b. View 106b presents a cross-section of the assembled emitter shaft portion 103a.

Most (or a significant portion) of the silicon shaft portion 103a fits into the metal sleeve 102b, as shown in view 103b. In order to fix the sleeve 102b on the silicon shaft portion 103a and achieve reliable electrical contact therebetween, generally at least one protruding portion 105b (recess) is formed on the sleeve 102b. Considering the dimensional tolerances of all three components (diameter of the silicon emitter shaft, inner diameter of the sleeve, and depth of the recess), the assembly operation is quite challenging (see the silicon shaft and recess on view 106b). Cross-sectional view, where the emitter shaft portion 103a and the sleeve 102b are not concentric because of the recess 105b).

Figure 1(c) shows an illustration of another design of the silicon emitter 100c. The emitter portion 101c is shown with a surface oxide layer ("skin layer") 102c, represented by the dashed line. The emitter 100c includes a silicon portion 101c and a sleeve 103c, and the sleeve 103c has a recess 104c. Sleeve 103c may have one or more segments/extensions 106c with grooves 107c (including various radii, grooves and necks, requiring special equipment to manufacture) . The emitter assembly is shown in view 105c. This design allows to keep the emitter in the nozzle and use the extension 106c to plug the extension 106c into a different socket or container.

Figure 2 shows an illustration of a conventional DC cleanroom ionization system 200, similar to that used in US Pat. No. 5,447,763. The ionizer has a pair of rods, a positive (+) rod 201 and a negative (-) rod 202, with single crystal silicon emitters. The rods are connected to dedicated positive and negative high voltage power (HVDC) supplies 203 (placed in the base). A cross-sectional view of the emitter rod is shown in view 204 . The end of the rod 202 has a socket connector 205 and a high voltage cable 206 connected to the HVDC power supply 203 . The socket 205 houses the silicon-based emitter 207 shown in view 204 . The rest of the rod 202 can act as a protection for the emitter 207, connector 205, and HV cable 206 from damaging forces. The rods are designed so that the silicon emitters 201, 202 are replaceable.

At least some of the goals of the exemplary embodiments of the present invention are to facilitate low particle emission by an economical silicon-based charge neutralization system. The composition of silicon-based emitters (with less than 99.99% and greater than 70% by weight of silicon) combined with high frequency corona discharge can make the goal of low particle emission a reality. For non-metallic silicon electrodes in ionization systems, the next main goal is to provide a reliable electrical connection between the silicon-based emitter and the HF high-voltage power supply.

Figure 3(a) shows a diagram of a silicon-based emitter 300a including a ground portion or a burnished portion 310a (ie, a treated surface portion) of the shaft portion 301a, according to an embodiment of the present invention. 310a), the shaft portion 301a can be inserted into a high-voltage socket (not shown). This portion 310a of the shaft surface 302a has a roughness H in the range of approximately 0.5 microns to 10 microns (see view 303a). During surface treatment, such as by polishing, the oxide "skin" previously on the shaft surface 302a will be destroyed and removed, or otherwise removed. The surface profile of the emitter shaft produced by grinding allows multiple points of contact with a high-voltage socket (not shown). Alternatively, a similar surface treatment can be applied to the rounded end 304a of the tail 314a of the emitter 300a. Emitter tip 305a, taper 306a, and portion 311a of shaft 301a have generally chemically polished surfaces.

Yet another embodiment of a silicon-based emitter is illustrated in Figure 3(b). According to this embodiment of the invention, the silicon-based emitter 300b includes a portion 310b of the emitter shaft portion 301b (ie, the treated surface portion 310b) having a metal coating or metal coating 302b (or a conductive coating or metal coating 302b) so that the portion 310b of the shaft portion 301b is a good surface conductor and protects the contact portion 316b of the emitter 300b from oxidation for a long time. Contact portion 316b may be in tail portion 314b of emitter shaft portion 301b.

Different known methods of silicon electroplating (eg, such as vacuum deposition, electrolytic plating, spraying, and others) can also be used. Electroplating materials like metals may include, for example, nickel, copper, silver, gold, and other metals, as well as alloys acceptable in the semiconductor industry.

Figure 3(c) shows a diagram of a silicon-containing emitter and an apparatus for monitoring the sheet resistance and/or volume resistance of the silicon-containing emitter, according to an embodiment of the present invention. This shows an example of the electrical property control operation of the silicon-based emitter 300c as shown in FIG. 3(c). Controlling and/or monitoring includes measuring the resistance value or monitoring the resistance value and/or composition of the emitter 300c or the treated surface portion 302c of the emitter 300c. Conductive electrodes 303c and 304c are attached or connected, respectively, to polished portion 302c (or treated surface portion 302c) and tail portion 314c of emitter shaft portion 301c of emitter 300c. A standard resistance value R measurement device 305 can be used to measure the resistance value R and record the resistance value R measurement. In this way, the resultant surface and volume resistivity and emitter composition can be monitored. The normal properties and composition required for a silicon-based emitter (having less than 99.99% to at least 70% silicon by weight) should have a resultant resistance value in the kiloohm range. After surface treatment and control operations, the emitter 300c can be plugged into a standard metal socket (not shown) to minimize the formation of a new layer of silicon oxide "skin".

At least some of the exemplary embodiments presented herein allow addressing two failure problems: (1) establishing a reliable electrical connection between the non-metallic silicon based emitter and socket; and (2) protecting the contact portion of the emitter from oxidation .

Figures 4(a) and 4(b) show diagrams of silicon-containing emitters with two variants of radially compressed spring sleeves and metal pins, according to various embodiments of the present invention. A silicon-containing emitter and metal pins are inserted into the sleeve, as discussed below. The silicon-based emitter 400a of Fig. 4(a) in the embodiment of the present invention will be described first. According to this exemplary embodiment, the emitter 400a includes an emitter portion 401a, wherein the silicon portion of the emitter portion 401a has a reduced length/shaft diameter ratio. A short silicon-based emitter portion 401a is attached to a metal radial compression spring sleeve 402a from one side 430 of the sleeve 402a. The other side 431 of the sleeve 402a is connected to a solid metal extension pin 403a. The metal pins 403a and 403b discussed herein may be metal electrodes 403a and 403b inserted into spring-loaded sleeves 402a and 402b, respectively. This pin 403a may have at least one (or more) groove and variable length "L2" as required by the design of the socket and ionization cell (including the reference electrode). For example, pin 403a includes grooves 435 and 436, but in other embodiments, pin 403a may have only a single groove. Pin 403a may be, for example, a solid metal pin or tube. Conventional, CNC, or automatic metal cutters, or other metal procedural methods may be used to manufacture pins 403a. View 405a shows a diagram or diagram of an emitter assembly 410a having a silicon emitter 400a, according to this exemplary embodiment. The radially compressed spring sleeve 402a has a significantly larger area in contact with the silicon portion 401a than the conventional sleeve 102b with the recess 105b shown in Figures 1(a) and 1(b). The result is a more reliable electrical connection and less mechanical stress applied to the brittle silicon emitter portion 401a. The design of a silicon emitter with a metal sleeve has some requirements to prevent "secondary" corona discharge from the edge of the sleeve to the nearby reference electrode. The main parameters that should be considered are illustrated in view 406a: D, D are the diameters of the silicon emitter shaft 440; L, L are the lengths of the exposed portions 441 of the silicon emitter shaft 440; α, α are the tapers of the shaft 440 and S, S is the thickness of the sleeve 402a. For a highly concentrated electric field on the emitter tip 421a of the silicon portion 401a (or on the emitter tip 421b of the silicon portion 401b), the first ratio S/D should be in the range of about 0.03 to 0.06. Another requirement regarding the distance between the emitter tip 421a and the sleeve 402 is the second ratio L/S: the second ratio L/S should be at (2-5)/[tan {tangent}(0.5α)] in the range. The parameter α is the taper angle of the tapered portion of the shaft portion 440 of the at least one non-metal emitter portion 401a or 401b. In one embodiment of the present invention, these conditions of the new silicon emitter design will satisfy several specifications/specifications: reliable electrical connection, good mechanical strength, and "secondary" electricity that will generate particle emission from the metal part Minimal possibility of halo.

Figure 4(b) shows an illustration of another embodiment of a silicon-based emitter 400b, including another configuration of a metal radially compressed spring sleeve 402b, where the emitter 400b and the sleeve 402b are concentric. In this case, the emitter 400 includes a silicon emitter portion 401b having a diameter D1 and one end 461 of the metal sleeve 402b having a diameter D3. The silicon emitter portion 401b has an emitter tip 421b. The portion 403b is a solid metal pin 403b having a diameter D4, and the other end 462 of the sleeve 402b has a diameter D2. The difference in diameters of the silicon emitter portion 401b and the metal sleeve 402b (D1>D3) produces the required compressive force to provide reliable or good electrical contact between the silicon portion 401b and the metal sleeve 402b. Similarly, the difference in diameter (D2 < D4) provides a reliable or good electrical connection between the metal sleeve 402b and the metal pin 403b. Views 404b and 406b illustrate assembled views of silicon emitter 400b. View 405b is a cross-sectional view illustrating silicon emitter 401b and sleeve portion 402b with large contact area, minimal contact pressure, and localized stress, according to this exemplary embodiment. Assembly operating system is simplified. Both exemplary embodiments (emitters 400a and 400b) use minimal amounts of expensive silicon-based materials, have large, reliable contact areas with non-metallic emitter shafts and metal sleeves, and to standard sockets or containers a good size match.

In some cases, silicon-based emitters can have problems initiating high frequency corona discharges and reliably generating ion production despite normal surface/volume resistance values and good electrical connection to high voltage sockets. Our experiments show that the core of the problem is the formation of a thick insulating oxide "skin" on the surface of the emitter tip (the "working foot" of the emitter). Another exemplary embodiment of the present invention addresses this problem. The shape of the tip of the silicon-containing emitter has some absolute effect on the rate and thickness of the insulating oxide "skin".

Figures 5(a), 5(b), and 5(c) are illustrations of three silicon-containing emitters, with different tapers and tips, according to various embodiments of the present invention. structure. The various tip and cone configurations shown in Figures 5(a), 5(b), and 5(c) determine the operating HF corona onset voltage and ionization current parameters.

In Figure 5(a), a silicon-based emitter 501 with a flat truncated tip is shown. This tip design is easy to generate annular high-frequency corona discharge (wherein the flat tip 510 is in contact with the taper 511 of the emitter 501 ). The emitter 501 reduces ionic current density and particle emission. However, it is characterized by a higher onset HF corona voltage. The tapered portion 511 has an angle value α with respect to the flat tip 510 .

The silicon based emitter 502 (Fig. 5(b)) has a small rounded tip 514 with a radius Z in the range of about 60 microns to 400 microns, which is cheaper to produce and minimizes corona currents fluctuation. Cone 516 (of emitter 502 ) extends from small rounded tip 514 .

The pointed silicon-based emitter 503 (Fig. 5(c)) has a pointed tip 520 having a radius Y in the range of about 40 microns to 50 microns (or less). This emitter 503 has the lowest corona onset voltage _Von . However, the emitter 503 has the highest ionic current density and the highest rates of sputtering, erosion, and oxide "skin" growth. The silicon-based emitter 503 is preferably used for ionization of oxygen-free gases, such as nitrogen or argon. The taper/cone 521 of the emitter 503 preferably has an angle α relative to the cusp-like tip 520 in the range of about 10-20 degrees. All silicon-based emitters (501, 502, 503) have compositions according to exemplary embodiments of the present invention, and when installed in embedded ionizers, ionization rods, and other charge neutralizers driven by HF AC voltage , can provide low particle numbers. The degree of sharpness and curvature of the tip (ie, the configuration of the tip) affects or determines ionizer operating parameters, including onset voltage, ion current, and ion balance, but they do not affect the scope of the present invention.

Another exemplary embodiment of the present invention addresses the problem of oxide "skin" growth on the silicon emitter tip. This embodiment uses a specific pattern of corona discharge to clean the silicon emitter tip from the oxide skin and assist in ionizer activation independent of the emitter profile.

6 shows a graphical representation of HF waveforms used to perform "soft" plasma cleaning of silicon-containing emitter tips during "start-up" periods of corona ionization, in accordance with an embodiment of the present invention.

A high voltage "HF start" type waveform 600 is applied to the emitter. This mode of high voltage drive may provide a set of short duration bipolar voltage bursts (bipolar pulses 605 in number from 1 to as many as hundreds) to the emitter during a start-up period (designated as the Ts period). Due to the very short duration of the power supply curve (millisecond, microsecond or less range), the HF corona associated with plasma has very limited energy. This approach prevents both rising temperature of the emitter tip and surface damage (sputtering, erosion, and particle emission) of the emitter tip. The short duration HF plasma surge only performs a "soft" cleaning of the emitter tip, freeing it from the silicon oxide skin. The duration of the "start" time period Ts, the amplitude of the burst pulses, and the number of pulses can vary and depend on the thickness of the silicon oxide skin layer, the gas medium, the design of the emitter tip, etc. The voltage amplitude of the HF glitch is significantly higher (approximately 25% to 100% or more) than the normal (operating) corona onset voltage (positive (+) Von vs. negative (-) Von) (in Figure 6 are shown by two horizontal dotted lines 610 and 615 respectively). The initial "start" mode helps initiate normal/operational high frequency corona discharge and ion generation. During normal/operational mode (during time Top), the high voltage amplitude can be only 10%-20% above the corona onset voltage ((+)Von or (-)Von) to minimize particle emission. In continuous operation mode, HF corona discharge can protect the silicon emitter from oxidation in a clean dry gaseous medium. Therefore, soft plasma cleaning of at least one non-metallic emitter is performed during the start-up period of the corona ionization period with a different voltage/power waveform than during the operation period.

FIGS. 7(a), 7(b), and 7(c) are diagrams illustrating examples of high frequency power supply voltage waveforms applied to silicon-based emitters during operating modes, according to embodiments of the present invention. Show. Different operating HF voltage waveforms effectively produce bipolar ionization of silicon-based emitters. The function of the high frequency AC voltage is to generate ions of two polarities (positive and negative) with a minimum drive voltage. In order to generate ions, the peak voltage (positive and negative peak voltage) must exceed the corona initiation voltage. As shown in Figure 7(a), the high frequency AC voltage curve 700 is continuous, but the voltage curve can also be adjusted to be continuous or discontinuous and periodic.

Figure 7(a) presents a supply voltage 700 in the form of a continuous sine wave, which can have frequencies ranging from about 1 kHz to as high as 100 kHz. The positive and negative voltage amplitudes of the voltage 700 are higher than the positive corona onset voltage (+) Von 705 and lower than the negative corona onset voltage (-) Von 710 . This voltage-type waveform 700 provides maximum power to the silicon-based emitters described herein, and produces the maximum ionic current.

Figure 7(b) shows a graphical representation of a voltage waveform 750 that includes a plurality of sets of pulse trains 752 having an "on" period 755 and an "off" period 756 . The waveform 750 includes at least one modulated portion, wherein each modulated portion includes a pulse train 752 having an on period 755 and an off period 756 . During the on period 755 in the pulse train 752, the waveform 750 has an amplitude 758 that exceeds the positive corona onset voltage threshold 705 and exceeds the negative corona onset voltage threshold 710 for a particular emitter. During the off period 756 in the pulse train 752, the waveform 750 has an amplitude 760 that does not exceed the corona onset voltage thresholds 705 and 710. In the example of Figure 7(b), this amplitude 760 is a voltage magnitude of approximately zero. Additional details of waveforms 700, 750, and 780 in Figures 7(a), 7(b), and 7(c), respectively, are also described in common assignment to Peter Gefter et al. in commonly owned US Patent No. 8,009,405. During the "off" period 756, which may be a small duty factor, corona discharge (ion production) and particle emission cease. The duty factor can vary from about 100% down to about 0.1% or less, depending on the desired ion output. The minimum work factor helps to suppress particle emission and the erosion rate of the emitter.

Figure 7(c) is a graphical representation of another variation of the voltage waveform 780 in which the duty factor approaches approximately 100%, but the amplitude of the voltage applied to the silicon emitter periodically drops to a value below the corona onset voltage (Range from about 90% to about 50% or less of the corona onset voltage). The advantage of this waveform is that particle emission and high voltage swings (voltage/electric field changes) are minimized.

The waveform 780 includes at least one modulated portion, wherein each modulated portion includes a pulse train 782 having an on period 785 and an inactive period 786 . During the on period 785 in the pulse train 782, the waveform 780 has an amplitude 788 that exceeds the positive corona onset voltage threshold ((+)Vmax) 705 for the particular emitter and exceeds the negative corona onset voltage threshold ((( -) Vmax) 710. During the non-operational period 786 in the pulse train 782, the waveform 780 has an amplitude 790 that does not exceed the corona onset voltage thresholds 705 and 710, but the amplitude 790 is greater than zero volts.

FIGS. 8(a) and 8(b) are diagrams illustrating examples of modulated high-frequency voltage waveforms according to embodiments of the present invention. Figure 8(a) presents a continuously modulated waveform 800 resulting from mixing (combining) high frequency and low frequency voltages. The low frequency component (or offset voltage) is shown in Figure 8(b). This voltage waveform 850 generates ions primarily with high frequency components (similar to waveform 700 shown in Figure 7(a)) and moves ions from the emitter with low frequency components.

Embedded ionizers with silicon-based emitters can be used in the most critical operations/processes in the semiconductor industry (eg, environments like Airborne Particulate Cleanness Class 1). Figures 9(a), 9(b), and 9(c) present illustrations of a block diagram of an embedded ionizer and a simplified view of an ionization unit. With the design of the embedded ionizer, the application of the HF frequency voltage can be similar to the waveform shown in Figure 8(a), with the frequency range extending from about 20 kHz up to about 100 kHz.

Figure 9(a) shows a diagram of an ionization cell/chamber of an embedded ionizer in accordance with an embodiment of the present invention. A high frequency AC powered silicon based emitter 902a produces ions of both polarities. Air/gas flow 908a moves the ion flow from emitter 902a. Also shown in Figure 9(a), the ionization unit 900a is connected to the HF HV generator 901a. The silicon based emitter 902a is positioned in the socket 903a and is connected via a capacitor (C1) which is connected to the HF generator 901a. Emitter 902a may have a polished or metallized portion of the shaft, as previously discussed in Figures 3(a) and 3(b), respectively, to provide a reliable connection to socket 903a.

The emitter 901a is generally positioned in the middle portion of the air/gas channel 904a. Preferably, the reference electrode 905a is positioned on the outside of the channel 904a and near the outlet 906a of the channel 904a. The reference electrode 905a is connected to the control system 907a. When the peak voltage (positive or negative voltage) of the high frequency AC voltage (applied to the emitter 901a) exceeds the corona initiation voltage, positive ions 920 and negative ions 921 are generated from the emitter 901a. The air/gas stream 908a from an external source (not shown) still needs to move the resulting ion cloud towards distant target charge neutralization (not shown). The corona discharge near the tip 909a of the emitter 902a produces an intense HF plasma 910a with ions and electrons near the tip 909a of the silicon emitter 902a. The corona onset voltage is approximately (+) 5 to 6 kV for positive ions and (-) 4.5 to 5.5 kV for negative ions.

Minimize the generation/emission of corona by-products, such as plasma particles in .

Figure 9(b) shows another view 900b of the ionization cell and an illustration of the gas channels in block 901b, according to an embodiment of the present invention. Channel 902b has an inlet 933b and an outlet 934b. The silicon-based emitter 905b and socket 906b may be fabricated as an exchangeable unit, positioned in the cavity 960 of the channel 902b. Emitter socket 906b and reference electrode 907b are connected to high voltage HF power supply 908b. The ionized gas stream (represented by arrows 961 ) moves the ion cloud to the charged target 909b (like a wafer), and the ion cloud will neutralize these charges 965 on the charged target 909b.

Figure 9(c) shows a simplified block diagram of an embedded ionizer 900c with a silicon-based emitter 904c in accordance with an embodiment of the present invention. Positive and negative ions 901c are generated inside the ionization unit 902c. High voltage HV-HF power supply 903c provides the voltage and current required to generate ions 901c. The power supply 903c transmits the high frequency AC voltage to the silicon-based emitter 904c through the capacitor C1. The voltage on the silicon-based emitter 904c is relative to the reference electrode 905c.

A pressurized source of air, nitrogen, or argon is connected to the embedded ionizer 900c via the inlet to generate an air or gas stream 906c. Air or gas flow 906c entrains positive and negative ions 901c and carries ions 901c through ionizer outlet 934c towards a target (eg, target 909b of Figure 9(b)).

Embedded ionizer 900c includes control system 907c (control system 907c includes microprocessor 908c), gas pressure sensor 909c, corona discharge sensor 910c, and operational status indicator 911c. Embedded ionizer 900c typically operates in a semiconductor tool with wafer loading/unloading operations. This is why the embedded ionizer 900c can have a longer idle ("stop") period without corona discharge and gas flow. During these time periods, the tip of the silicon emitter may grow a silicon oxide layer. As previously discussed in the exemplary embodiments illustrated in Figures 3(a) and 6, the control system 907c initiates the gas ionization process by starting the high voltage power supply 903c in the "start" mode. The corona discharge sensor 910c and microprocessor 908c continuously monitor the state of the corona discharge until the point of intense and stable corona and ion generation is reached. After that, the control system 907c and the power supply 903c are switched to the normal operation mode.

Figures 10(a), 10(b), 10(c), and 10(d) are diagrams illustrating a simplified structure of a high frequency AC ionization bar 1000a according to an embodiment of the present invention, Detail with a nozzle with a silicon-based ion emitter. Figures 10(a) and 10(b) show views of a high frequency AC ionization rod 1000a with a plurality of original silicon-based emitters 1001a-1008a (as an example). Each silicon emitter has a stainless steel sleeve. The stainless steel sleeves are shown as sleeve 1020c in Fig. 10(c) and sleeve 1020d in Fig. 10(d). Each stainless steel sleeve is installed in the nozzle. Each nozzle has a socket and optionally one or two air/gas injection holes. Cross-sectional views of the nozzles are shown as nozzle 1030c in Figure 10(c) and nozzle 1030d in Figure 10(d).

The sockets 1009c are connected to a common high voltage bus, and the holes and manifolds (not shown) are located inside the housing 1010a of the ionizer bar 1000a. A cross-sectional view 1040 of nozzle 1030d shows the relative positions of silicon emitter 1003d (with sleeves and grooves as previously discussed in Figures 4(a) and 4(b)) and hole 1004d. The busbar distributes HF power from a high voltage AC power supply to each nozzle and emitter. The HF-HV power supply with the microprocessor-based control system is preferably located within the same housing 1010a. The silicon-based ion emitters receive HF AC voltages in the range of about 6kV to 8kV with a fundamental frequency of about 10kHz to 26kHz (similar to that shown in Figure 7(a)). This HF high voltage produces a corona discharge between each of the emitters 1001a to 1008a and the reference electrode 1011a. This high frequency AC voltage by itself is sufficient to produce clean bipolar ionization when the composition of the emitter uses silicon in the range of less than 99% to greater than 70%. As discussed previously, high frequencies by themselves cannot move the ion cloud away. The HF ionizing rod 1000a is typically mounted in a flat panel or semiconductor tool at a short distance from the target (eg, about 50mm to 300mm). In this case, the electric field of the charged target (not shown) attracts ions of opposite polarity. However, for efficient charge neutralization at longer distances (eg, about 400 mm to 1500 mm), the ion cloud requires the assistance of an air/gas flow or an electric field or a combination of both. Typically, HF ionizing rods are used in combination with HEPA filters that provide laminar flow of clean air.

Figure 8a shows a modulated HF waveform 800 that generates an additional low frequency field (with a frequency of approximately 0.1 Hz to 200 Hz) to assist in ion delivery to the target. During period T2, the amplitude 802 of the positive voltage wave 804 and the amplitude 806 of the negative voltage wave 808 are nearly equal, and as a result, the offset voltage approaches zero and the ion cloud oscillates near the silicon emitter. Conversely, during periods like T1, the voltage waveform 800 has a positive offset 810, and the ion cloud of positive polarity (which repel each other) moves to the target (see Figure 8(b)). Similarly, during a time period like T3, the voltage waveform 800 has a negative offset 815, and the negative polarity ion cloud (which repels each other) moves to the target. The frequency and amplitude of the offset voltage depend on the distance between the ionizing rod 1000a and the target.

The high frequency ionizing rod 1000a with a silicon-based emitter is capable of producing low emission to produce clean air/gas ionization and neutralize fast moving large objects (like flat panel displays) at distances such as about 400mm up to 1500mm charge.

Another embodiment of the present invention provides a method for low emission charge neutralization wherein at least one of the aforementioned non-metallic emitters includes a reduced silicon portion length/shaft portion diameter ratio.

Another embodiment of the present invention provides a method for low emission charge neutralization, wherein said sleeve comprises a metal radial compression spring sleeve, and wherein at least one emitter, metal pin, and the diameter of the sleeve are different A compressive force is generated to provide reliable electrical connection between at least one emitter, metal pins, and metal electrodes.

Another embodiment of the present invention provides an apparatus for low emission charge neutralization wherein at least one of the aforementioned non-metallic emitters includes a reduced length/shaft diameter ratio.

Another embodiment of the present invention provides an apparatus for low emission charge neutralization, wherein the above-mentioned sleeve comprises a metal radial compression spring sleeve, and wherein at least one emitter, metal pin, and the diameter of the sleeve are different A compressive force is generated to provide reliable electrical connection between at least one emitter, metal pins, and metal electrodes.

Another embodiment of the present invention provides an apparatus and method for producing a reliable, low particle emission charge neutralizer by combining: having a chemical composition between less than 99.99% to at least 70% by weight A range of silicon non-metal ion emitters, emitter geometries, and surface treatments (fabrication), and connection configurations between emitters and high voltage power supplies operating in the high frequency range. In this combination, the emitter reliably produces a high frequency corona discharge, which is characterized by a low onset voltage and low particle emission. This combination is valid for many different types of cleanroom ionizers/charge neutralizers targeted for use in Class 1 cleanrooms. The combination of the silicon-containing emitter and high frequency AC voltage produces an ionizer that is cleaner than conventional ionizers (based on particle counts greater than 10 nanometers). This improvement in cleanliness has been experimentally determined by the inventors.

The above description of exemplary embodiments of the present invention, including that described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the art will recognize.

These modifications can be made to the present invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the present invention is entirely determined by the following patentable scope, which is to be interpreted in accordance with established principles for the interpretation of patentable scope.

100a: Emitter 100c: Emitter 101a: Tip 101b: Non-metallic silicon parts 101c: Emitter part 102a: Cone 102b: Stainless steel tube (sleeve) 102c: skin layer/layer (surface oxide layer) 103a: Shaft 103b, 104b: Views 103c: Sleeve 104a: tail 104c: Recess 105b: Recess (protrusion) 106b: Views 106c: Section/Extension 107c: Groove 200: Ionization System 201: positive (+) stick

202: negative (-) stick

203: High Voltage Power (HVDC) Supply

204: View

205: Socket Connector

206: High Voltage Cable

207: Silicon Emitter

300a: Silicon emitter

300b: Silicon Emitter

300c: Silicon Emitter

301a: Shaft

301b: Shaft

301c: Shaft

302a: Shaft surface

302b: Metallic coatings (metallic coatings)

302c: Treated surface part

303a: View

303c, 304c: Conductive electrodes

304a: Rounded end

305: Measuring device

305a: tip

306a: Cone

310a: Treated surface parts (grinded parts, polished parts)

310b: Treated surface parts

311a: Parts

314a: tail

314b: tail

314c: tail

316b: Contact part

400a, 400b: Silicon emitter

401a, 401b: Emitter part

402a, 402b: Sleeve

403a, 403b: Metal extension pins (metal electrodes)

404b: view

405a: View

405b: View

406a: View

406b: view

410a: Emitter Components

421a, 421b: tip

430: Side

431: Side

435, 436: groove

440: Shaft

461: end

462: end

501: Silicon Emitter

502: Silicon Emitter

503: Silicon Emitter

510: Flat tip

511: Cone

514: round tip

516: Cone

520: pointed tip

521: Cone / Cone

600: Waveform

605: Bipolar Pulse

610, 615: horizontal dotted line

700: High frequency AC voltage curve

705: Positive corona onset voltage (+)Von

710: Negative corona onset voltage (-) Von (negative corona onset voltage threshold)

750: Voltage waveform

752: Burst

755: Opening Period

756: Closing Period

758: Amplitude

780: Voltage waveform

782: Burst

785: Opening Period

786: Non-operational period

788: Amplitude

790: Amplitude

800: Waveform

802: Amplitude

804: Positive Voltage Wave

806: Amplitude

808: Negative Voltage Wave

810: positive offset

815: negative offset

850: Voltage waveform

900a: Ionization Unit

900b: View

900c: Ionizer

901a: HF HV Generator

901b:Block

901c: positive and negative ions

902a: Silicon Emitter

902c: Ionization Unit

903a: Socket

903c: Power Supply

904a: Air/Gas Passage

904c: Silicon Emitter

905a: Reference Electrode

905b: Silicon Emitter

905c: Reference Electrode

906a: Export

906b: Socket

906c: Air flow or gas flow

907a: Control Systems

907b: Reference electrode

907c: Control Systems

908a: Air/Gas Flow

908b: High Voltage HF Power Supply

908c: Microprocessor

909a: tip

909b: Charged Target

909c: Gas pressure sensor

910a:HF Plasma

910c: Corona Discharge Sensor

911c: Operational Status Indicator

920: positive ion

921: Negative Ion

933b: Entrance

934b: Export

934c: Ionizer outlet

960: cavity

961: Arrow

965: Charge

1000a: High Frequency AC Ionizing Bar

1001a-1008a: Silicon Emitters

1003d: Silicon Emitter

1004d: Hole

1009c: Socket

1010a: Shell

1020c, 1020d: Sleeve

1030c, 1030d: Nozzle

C1: Capacitor

D: diameter

D1, D2, D3, D4: Diameter

L2: variable length

R: resistance value

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings, wherein like reference numerals refer to like parts throughout the various views, unless otherwise indicated.

It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

Figure 1(a) is an illustration of a conventional single crystal silicon ion emitter or (generally) a non-metal ion emitter.

Figures 1(b) and 1(c) show diagrams of conventional components and components with single crystal silicon emitters with metal sleeves and grooves.

Figure 2 shows a diagram of a conventional DC clean room ionization ceiling system with two monocrystalline silicon emitters.

Figure 3(a) shows an illustration of a silicon-containing emitter including a portion of the emitter axis (or treated surface portion) having a preselected surface roughness, in accordance with an embodiment of the present invention.

Figure 3(b) shows an illustration of an emitter including a partially conductive surface coating or a partially conductive surface coating (or other type of treated surface portion, according to another embodiment of the present invention) ) part of the emitter shaft.

Figure 3(c) shows a schematic diagram of a silicon-containing emitter and a device for monitoring the surface resistance and/or volume resistance of the emitter, according to an embodiment of the present invention.

Figures 4(a) and 4(b) show diagrams of silicon-containing emitters with two variants of radially compressed spring sleeves and metal pins, according to various embodiments of the present invention.

Figures 5(a), 5(b), and 5(c) are illustrations of three silicon-containing emitters, with different tapers and tips, according to various embodiments of the present invention. structure.

6 shows a graphical representation of HF waveforms used to perform "soft" plasma cleaning of silicon-containing emitter tips during "start-up" periods of corona ionization, in accordance with an embodiment of the present invention.

Figures 7(a), 7(b), and 7(c) illustrate examples of high frequency power supply voltage waveforms applied to silicon-based emitters during operating modes in accordance with various embodiments of the present invention icon.

Figures 8(a) and 8(b) are diagrams illustrating examples of modulated high frequency voltage waveforms according to various embodiments of the present invention.

Figure 9(a) shows a diagram of an ionization cell/chamber of an embedded ionizer in accordance with an embodiment of the present invention. High frequency AC powered silicon-based emitters generate ions of both polarities. The air/gas flow moves the ion flow from the emitter.

Figure 9(b) shows a diagram of an ionization cell and a gas channel according to an embodiment of the present invention.

Figure 9(c) shows a simplified block diagram of an embedded ionizer with a silicon-based emitter in accordance with an embodiment of the present invention.

Figures 10(a), 10(b), 10(c), and 10(d) illustrate a simplified structure of a high-frequency AC ionization rod with silicon-based ions according to embodiments of the present invention Illustration of a detail of the emitter's nozzle.

300a: Silicon emitter

301a: Shaft

302a: Shaft surface

303a: View

304a: Rounded end

305a: tip

306a: Cone

310a: Treated surface parts (grinded parts, polished parts)

311a: Parts

314a: tail

Claims (20)

A method for low emission charge neutralization, comprising the steps of: generating an alternating current (AC) and a high voltage; transmitting the high voltage to at least one point-type silicon-based non-metal ion emitter, the at least one A point-type silicon-based non-metal ion emitter is provided with a tip, a taper, a shaft and a tail; wherein the taper is between the tip and the shaft; wherein the shaft is between the taper and the tail wherein the high voltage and the alternating current are in a high frequency range of 1 kHz to 100 kHz; wherein the at least one point-type silicon-based non-metal ion emitter comprises greater than 72.00 wt % silicon and less than 99.99 wt % percentage of silicon; wherein the at least one point-type silicon-based non-metal ion emitter comprises at least a portion of the treated surface of the shaft portion or/and the tail portion, the treated surface having an increased surface conductivity or a lower resistance; and generating ions from the tip of the emitter in response to the treated surface of the shaft or/and the tail of the emitter contacting the high voltage and the alternating current in the high frequency range. The method of claim 1, wherein the portion of the treated surface of the shaft portion or/and the tail portion of the at least one point-like silicon-based non-metal ion emitter includes a region having a preselected roughness , the preselected roughness is in the range of 0.5 microns to 10 microns, the preselected roughness The selected roughness results from abrasive or sanding treatments. The method of claim 1, wherein the portion of the treated surface of the shaft portion or/and the tail portion of the at least one point-type silicon-based non-metal ion emitter comprises a metal coating or metal coating. The method of claim 1, further comprising the step of: providing a measuring device for monitoring a surface or/and volume resistance value and composition of the at least one point-type silicon-based non-metal ion emitter. The method of claim 1, wherein the shaft portion of the emitter including a silicon-like portion and a metal electrode are inserted into a spring-loaded sleeve. The method of claim 1, further comprising the step of: performing a plasma cleaning of the at least one dotted silicon-based non-metal ion emitter during a start-up period of corona plasma ionization, the Corona Plasma Ionization is produced by a voltage/power waveform that includes short-duration bursts of pulses that are 25 higher than a voltage/power waveform during a typical (operating) period % to 100% of an amplitude. The method of claim 1, wherein in order to minimize particle emission from the ion emitter, during an operation period a minimum starting HF voltage amplitude and/or a lower duty factor is to be used A corona discharge voltage waveform is applied to the ion emitter. The method of claim 1, wherein the at least one point-like silicon-based non-metal ion emitter comprises an assembly of a non-metal part/part and a metal part/part; wherein the metal part/part constitutes a a compression spring sleeve positioned on the shaft portion of the non-metal ion emitter; wherein the assembly includes a first ratio S/D in the range of about 0.03 to 0.06; wherein S is receiving the at least one a thickness of the sleeve of the point-type silicon-based non-metal ion emitter; and wherein D is a diameter of the shaft portion of the at least one point-type silicon-type non-metal ion emitter. The method of claim 1, wherein the at least one point-like silicon-based non-metal ion emitter comprises a second ratio in the range of (2-5)/[tan{tangent}(0.5α)] L/S; wherein L is a length of an exposed portion of an axial portion of the at least one point-type silicon-based non-metal ion emitter; wherein S is the reception of the at least one point-type silicon-type non-metal ion emitter a thickness of a sleeve; and wherein α is a taper angle of a tapered portion of the shaft portion of the at least one point-type silicon-based non-metal ion emitter. A device for low-emission charge neutralization, comprising: at least one point-type silicon-based non-metal ion emitter, the at least one point-type silicon-type non-metal ion emitter is equipped with a tip, a cone part, a shaft part and a tail part; wherein the cone part is between the tip and the shaft part; wherein the shaft part is between the cone part and the tail part; wherein the at least one point-like non-metal ion emission of silicon The electrode includes more than 72.00% by weight of silicon and less than 99.99% by weight of silicon; wherein the at least one point-type silicon-based non-metal ion emitter includes at least a portion of the treated surface of the shaft portion or/and the tail portion, The treated surface has increased surface conductivity or lower resistance value; and wherein the tip of the emitter responds to the shaft or/and the tail of the emitter in contact with the treated surface at 1 kHz to 100 kHz Ions are generated by a high voltage and an alternating current (AC) in the high frequency range. The apparatus of claim 10, the portion of the treated surface of the shaft portion or/and the tail portion of the at least one point-like silicon-based non-metal ion emitter includes a region having a preselected roughness, The preselected roughness is in the range of 0.5 microns to 10 microns, the preselected roughness being due to the grinding or buffing process. The apparatus of claim 10, wherein the portion of the treated surface of the shaft portion or/and the tail portion of the at least one point-type silicon-based non-metal ion emitter includes a metal coating or metal coating. The apparatus of claim 10, wherein a surface or/and volume resistance value and composition of the at least one point-type silicon-based non-metal ion emitter are monitored. The apparatus of claim 10, wherein the shaft portion of the emitter including a silicon-like portion and a metal electrode are inserted into a spring-loaded sleeve. 11. The apparatus of claim 10, wherein a soft plasma cleaning of the at least one dotted silicon-based non-metal ion emitter is performed during a start-up period of corona plasma ionization, the corona plasma Ionization is produced by a voltage/power waveform that includes short-duration pulsed bursts having a voltage/power waveform that is 25% to 100% higher than a voltage/power waveform during a typical (operating) period an amplitude of . The apparatus of claim 10, wherein in order to minimize particle emission from the ion emitter, a corona discharge voltage is to have a minimum starting HF voltage amplitude and/or a lower duty factor during a period of operation A waveform is applied to the ion emitter. The apparatus of claim 10, wherein the at least one point-like silicon-based non-metal ion emitter comprises an assembly of a non-metal part/part and a metal part/part; wherein the metal part/part constitutes a a compression spring sleeve positioned on the shaft portion of the non-metal ion emitter; wherein the assembly includes a first ratio S/D in the range of about 0.03 to 0.06; wherein S is receiving the at least one A thickness of the sleeve of the point-type silicon-based non-metal ion emitter; and wherein D is the at least one point-type silicon-type non-metal ion emission A diameter of the shaft portion of the pole. The apparatus of claim 10, wherein the at least one point-like silicon-based non-metal ion emitter comprises a second ratio in the range of (2-5)/[tan{tangent}(0.5α)] L/S; wherein L is a length of an exposed portion of an axial portion of the at least one point-type silicon-based non-metal ion emitter; wherein S is the reception of the at least one point-type silicon-type non-metal ion emitter a thickness of a sleeve; and wherein α is a taper angle of a tapered portion of the shaft portion of the at least one point-type silicon-based non-metal ion emitter. A device for low emission charge neutralization, comprising: a silicon-based non-metal ion emitter, the silicon-based non-metal ion emitter is provided with a tip, a taper, a shaft and a tail; wherein the taper is in the between the tip and the shaft; wherein the shaft is between the taper and the tail; wherein the silicon-based non-metal ion emitter comprises greater than 72.00% by weight of silicon and less than 99.99% by weight of silicon; wherein the The silicon-based non-metal ion emitter includes at least a portion of the treated surface of the shaft portion or/and the tail portion, the treated surface having a higher surface conductivity or lower resistance value than the shaft portion and the tail portion. The apparatus of claim 19, wherein the tip of the emitter is responsive to the treated surface of the shaft or/and the tail of the emitter contacting a 1 kHz to 100 kHz Ions are generated by a high voltage and an alternating current (AC) in the high frequency range.

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