Basic knowledge of plasma processing
The first step is to know what is a plasma and what characteristics you have in order to understand plasma processing.In this series, we will explain the basic knowledge of plasma processing six times.In the first edition, the basic concept of plasma and the collision between the charged particles and the molecules that occur in them, the electronic collision reaction, which is an important subdivision, and the electronic temperature that occurs is abnormal.I will explain the realization of non -equilibrium plasma that is high.
Lottery
1st: Types and features of plasma
In the General Electric (GE) Research Institute, IRVING LANGMUIR, an American chemist and physicist who was immersed in research on low -gas pressure release called glow discharge (imagine fluorescent light), 1928In a paper published in the year, the uniform object was named Plasma.By the way, Lang Mure is a superman researcher who has achieved revolutionary results not only in plasma but also in several different fields, and won the Nobel Prize in the surface in 1932 in the field of surface science.His basic research has contributed to GE's business brilliantly and can be said to be an example of corporate researchers.We recommend that you look into Lang Mure's achievements.
さて、プラズマと名付けられた物質はどんなものなのでしょうか。昔、理科の授業で「物質の三態」という言葉を聞いたことがあると思います。水（H2O）を例に取ると、1気圧の下で0℃以下のときは固体（氷）に、これを加熱していくと液体に、さらに加熱すると100℃以上で気体（水蒸気）になり、これを物質の三態と呼びます。
では、ここからさらに加熱を続けると、どうなるでしょうか。H2O分子は……
>>第1回 第1章の続きを読む（PDFダウンロード）
プラズマ処理を考える上で、電子衝突による分子の解離反応は特に重要です。例えば、最も単純な水素分子（H2）の場合、これが解離反応により2つの水素原子（H）に分解されます。水素原子には未結合手があるため反応性は非常に高く、このような原子（分子の場合もある）をラジカル、またはフリーラジカル（遊離基）と呼びます。こうしたラジカルが、プラズマを用いた材料処理で重要な役割を果たします。
Plasma has different properties depending on its ionization (neutral molecules and ionic density ratio to atoms).It is common for plasma processing to use a low oloresic (usually less than 1 / 10,000 or less).In that case, it is sufficient to consider neutral molecules and atoms for the opponent where electrons and ions collide, and can ignore the collision between charcoal particles.One of the most important collision reactions is the collision between electrons, neutral atoms, and molecules.When an electronic E with sufficient kinetic energy collides with atom X, a ionic reaction that flies electrons from atoms occurs with a certain probability.
e（高速）+ X → e（低速）+ X++ e
Also, when electrons collide with molecules (tentatively, Niwara and molecular XY), ...
>>第1回 第2章の続きを読む（PDFダウンロード）
Plasma is composed of electrons, ions, and neutral molecules (including atoms), and they have random heat exercises.The particle has various speeds determined by the speed distribution of Maxwell (distribution function in which the speed of the gas molecule is obeyed in thermodynamic equilibrium state), and the indicator of the average motion energy of those particles is the temperature.Is stipulated in.
平衡プラズマとは、電子温度とイオンや原子の温度が熱平衡状態、すなわち同じである状態を指します。電子、イオン、中性分子の温度をそれぞれTe、Ti、Tgで表すと、熱平衡状態にある平衡プラズマでは、Te=Ti=Tgです。
非平衡プラズマは、電子温度がイオンと原子の温度よりも高い状態を指します。プラズマ処理で一般的に用いられる弱電離プラズマでは、Te≫Ti≒Tgとなっています。例えば、蛍光灯のようなグロー放電では、放電管に触れても分かるように、TiやTgは室温より多少高い程度にもかかわらず、電子温度Teは数万度にも達します。
図2に、水素分子H2、窒素分子N2、酸素分子O2のガスにおける円筒放電管内のプラズマ部の電子温度と、pR（p：ガス圧、R：放電管の半径）の関係を示します。ここで、ガス圧の単位Torrは1Torr＝1/760気圧、電子ボルト(eV)で表した電子温度は1eV＝11,600Kに相当します。pR=1(Torr cm)（ガス圧1/760気圧で放電管の半径1cmの場合など）では、電子温度は約2万度になります。
図2：H2、N2、O2ガスにおける円筒放電管内のプラズマ部の電子温度と、pR（p:ガス圧、R:放電管の半径）の関係（参考：市川幸美他、プラズマ半導体プロセス工学、内田老鶴圃、2003年、P.20）なぜこのような状態が実現されるのかを、簡単に説明します。それは、イオンと電子の質量の差に起因します。質量m1の剛体球1が、質量m2の静止している剛体球2に衝突する、古典的な弾性衝突モデルを考えてみましょう。衝突には、正面衝突からかすかに触れ合う程度のものまで、さまざまな場合があります。1回の衝突で剛体球1が失うエネルギーの平均値を求め、それと衝突前の運動エネルギーとの比率を衝突損失係数fと定義すると、結果は次式のようになります。
電子と中性分子の衝突の場合には、電子の質量が中性分子の質量に比べてはるかに小さい（数千分の1以下）ため、上式はf=2m1/m2となり、1回の衝突で、電子は持っているエネルギーの数千から数十万分の1のエネルギーを失うだけです。それに対し、イオンの場合にはその質量は中性分子とほぼ同じであるため、上式はf=1/2となり、1回の衝突でほぼ半分のエネルギーを中性分子に与えることになります。
On the other hand, depending on the electric field that exists in the plasma, ...
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2nd: How to generate plasma
Last time, we introduced the types and characteristics of plasma.This time, I will explain how to generate plasma.Various plasma can be generated due to discharge conditions and structures.This article describes the main plasma sources used for plasma processing technology that will be touched after the next time.Specifically, for glow discharge plasma, arc discharge plasma, and atmospheric pressure low temperature plasma, we will discuss the characteristics of discharge forms, electronic temperature, and gas temperature, and explain various plasma processing technology.
Last time, I will explain the glow discharge plasma that was taken up as a representative example of a weak oltopathic plasma.Taking a cylindrical discharge tube as an example, a discharged voltage is applied to the electrode placed at both ends by enclosing a gas that is reduced to about 1,000th (100 pa) to about 1,000th.Is generated (Fig. 1).Glow discharge is a sustainable discharge phenomenon in low pressure gas.Even if the length of the discharge tube is changed, the structure of the cathode part does not change, and only the length of the portion of the pillar (corresponding to the glowing part of the fluorescent light) changes.In this area, the density of ions and electrons is uniform in the length direction (changes in the diameter direction), and the potential change is linear, so the electric field (tilt of potential change) is uniform.
Glow discharge has long been researched as a representative example of non -equilibrium plasma (see the 1st Chapter 3 Equilibrium Plasma and Non -equilibrium plasma), and is also an important plasma in application.As mentioned earlier, in these plasma, the electron temperature is about two digits higher than the ion or neutral molecular (gas) temperature, and the molecules are dismissed (decomposed) by the collision between electrons and molecules that move around at high speed.As a result, a highly reactive free radical (free base) is generated and applied to plasma processing.
図1：直流グロー放電プラズマの構造と電位分布The cathode area consists of a cathode down, negative gallery, and a dark part of the Faraday in order from the cathode, and the length is several cm (it changes depending on the gas and gas pressure).A large potential difference (high electric field) is applied to the cathode down, which accelerates the positive ions toward the cathode and collides at high speed.When high -speed ions collide, electrons are bullet from the molecules that make up the cathode and are released to the electrode surface.This is,……
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アーク放電とは、放電管に大電流を流すことにより発生する放電です。グロー放電の代表的な放電電流密度の上限値は、数100mA/cm2程度です。ここから更に電流を増やすと、アーク放電と呼ばれる放電形態に移行します。アーク放電では、電極間の電圧が10V程度まで極端に低下します。その主な理由は、グロー放電の陰極降下部が消滅する、また電子密度の増加に伴う陽光柱領域の電気伝導度の増大により電圧降下が小さくなることです。
アーク放電では、イオン温度やガス温度が上昇して平衡プラズマに近づきます。図2は、水銀アーク放電を例に、ガス圧に対する電子温度Teとガス温度Tgの変化を示したものです。低ガス圧の時は、グロー放電のように、TeがTgに比べて極端に高い非平衡状態になっています。しかし、大気圧になるとTeとTgはほぼ同じになります。これは、……
>>第2回 第2章の続きを読む（PDFダウンロード）
アーク放電の話と矛盾するにもかかわらず、Te>Tgの非平衡プラズマを大気圧で実現できることが、2000年代の初めに報告されました。大気圧でアーク放電を行う場合、電子衝突によりTgが高温になるためにはある特定の時間がかかります。そこで、ガスが加熱される前に放電を止めることを繰り返す(パルス放電)と、Tgはそれ程に上がらずTeだけが高くなる、非平衡な大気圧プラズマが実現されます。
An dielectric barrier discharge is often used to realize such pulse discharge.The dielectric barrier discharge is a discharge that is generated in the gas that adds an exchange voltage to the gas through a dielectric, which is an insulator.I will briefly explain the principle.As shown in FIG. 3, the barrier discharge has a structure in which one or both of the electrodes or both are covered with glass -like insulators (dielectrics).Let's add a large positive DC voltage to this upper electrode.Then, the electric field accelerates the electrons toward the upper electrode, causing a ionizing collision to cause discharge.On the other hand, the positive ion moves toward the lower electrode.However,……
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3rd: Thin film sedimentation technology
Last time, we introduced various plasma methods.This time, we will explain the thin film deposits (formation) technology using plasma.By applying a non -equilibrium plasma, a semiconductor thin film or a polymer thin film can be formed without having the substrate or gas at a high temperature.A typical example is the Amorphus Si semiconductor film.Other film -based methods can easily obtain high -quality materials that are difficult to realize, making it an indispensable material for the realization of high -performance solar cells.
プラズマCVD（Plasma CVD、あるいはPlasma enhanced CVD）とは、プラズマを援用する型式の化学気相成長（Chemical Vapor Deposition：CVD）の一種です。CVDは、LSI（Large Scale Integration：大規模集積回路）などの半導体素子の作製に用いられる多結晶シリコンや窒化ケイ素Si3N4膜の代表的な薄膜形成法の1つです。通常のCVDでは、例えばSi薄膜を形成する場合には、外側を電気炉などで囲って加熱できるようにした石英管の中に膜を形成する基板を置き、そこにシランSiH4ガスを流します。管内の温度を600℃以上に加熱すると、SiH4分子の一部は熱エネルギーによりシリレンSiH2+水素H2のような解離反応により分解されます。
熱エネルギーによる解離機構は次のようなものです。温度を上げていくと、分子の運動速度が大きくなります。すると、それらの相互衝突により分子を構成する原子間の振動が激しくなり、そこから飛び出してしまうほど振幅の大きくなる分子が、ある確率で存在し始めます。その確率は、温度が高いほど大きくなります。この解離反応により生成されたSiH2のようなラジカルが基板まで拡散して行き、次々と付着して膜を形成します。このように、ガスの加熱により分子を分解して膜形成を行うことから、この製膜方法は熱CVDとも呼ばれています。
On the other hand, plasma CVD is a method that uses plasma to decompose gas.As described in the previous time, glow discharge has realized a non -equilibrium state in which only electronic temperature reaches tens of thousands of degrees.As a result, even when the gas temperature is low, the molecule is disassembled and decomposes due to a collision with high -speed electrons.Figure 1 shows an example of a plasma CVD device.
図1：容量結合型プラズマCVDの原理図Set a parallel flat electrode in the vacuum container and place the substrate that you want to add a film on the ground electrode.When the gas that is used as a raw material under reduced pressure state is discharged, the raw material gas is decomposed by an electronic collision in the plasma to generate a radical, which spreads to the substrate, and is deposited as a film.Therefore, ...
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アモルファスSi半導体（以下、a-Si）は非晶質Siとも訳され、結晶Siのように規則的な原子配列を持たない材料のことを指します（図2）。従来の熱CVDや蒸着により堆積したa-Si膜では、膜中に存在するシリコンの未結合手(ダングリングボンド)による欠陥が多数(～1020cm-3)存在し、半導体デバイスに必要となる高品質な膜は得られません。
図2：Si半導体の二次元モデルところが、プラズマCVDでa-Si膜を形成すると、低温製膜(通常は基板温度200°C程度)であるため、水素が放出されることなく膜中に多数取り込まれます。そのため水素化アモルファスSiと呼ばれ、厳密にはa-Si:Hと書きます。これらの水素がダングリングボンドと結合して欠陥を補償するため、欠陥密度が1015-1016cm-3まで低下し、p型、n型に制御可能な良質な半導体膜が得られます。しかも、p型、n型Siは、SiH4ガスに不純物を含むガス(p型ではB2H6、n型ではPH3など)をわずかに混ぜて放電させることで作ることができます。このことが発見されたのは、1970年代のことです。
By the way, solar cells are basically a diode that is based on PN joining.If you use a plasma CVD, you can form a solar cell on a large glass substrate as long as the electrode is enlarged.In addition, a thin film transistor that controls the ON and OFF of the liquid crystal pixel, ...
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プラズマCVDと同じ原理を有機物に適用したのがプラズマ重合です。ポリエチレンのような高分子(ポリマー)材料を作るには、従来の方法ではエチレンC2H4のような原料となるモノマーを加圧・加熱し、触媒反応などを用いながら重合します。モノマーとはガスや液体の形で小さな分子が集まった単量体をいいます。
On the other hand, in plasma polymorphism, a gas -shaped monomer is introduced to generate a glow discharge plasma, and a film -like polymer is accumulated on the substrate placed inside.For example, discharge an ethylene gas forms a polyethylene thin film.This can be realized because high -speed electrons are cut off by high -speed electrons and easy to generate radicals.Plasma polishing has the following features:
Generally, the plasma polymerization membrane is high density and hard, ...
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4th: etching technology
Last time, I explained the plasma technology that generates materials.This time, I will explain the etching technology that cuts and processes materials.We will introduce the principles and applied products for this technology that can be used only for plasma, as well as chemical etching alternatives using etching solution.
Dry etching is a method of etching materials by reactive gas (etching gas), ions, and radicals. Processing that makes a groove in the ingredients or carved a pattern is called etching. This is an indispensable technology for creating semiconductor devices. Until the 1960s, there was only a method called wet etching using etching solution, and this method was used exclusively for devices. In this method, the device is inexpensive, and it has achieved high productivity because it can handle a large amount of siliconweha (material for semiconductor element manufacturing) at once. However, it was difficult to control the etching reaction speed, and it was not suitable for ultra -fine processing required for IC and LSI production. Therefore, the application of plasma was considered as a means to replace this wet etching, and from the first half of the 1970s, it has been introduced into IC production.
プラズマを用いるエッチングはプラズマエッチング、あるいは液体を使わないことからドライエッチングと呼ばれます。その原理は、薬液によるウェットエッチングを気相に置き換えたものです。前回説明した、プラズマCVDと同様の装置を用いて、そこにエッチング用のガスを導入します。プラズマ中で電子衝突により解離、生成されたラジカルが、エッチング反応の主役になります。シリコン（Si）のエッチングを例にとると、四フッ化メタン（CF4）を含むガスを放電させ、プラズマ中で以下のような解離反応によりフッ素（F）原子を生成させます。
CF4+ e → CF3+ F + e
F Atoms spread to the SI substrate, and the following reacts on the surface and etched the SI (Fig. 1).
Si（固体） + 4F → SiF4（気体）
図1：FラジカルによるSiエッチングの原理Using this method will stabilize the etching speed, and if the discharge is stopped, the etching will be stopped, so that the control is greatly improved compared to wet etching.However, if such electrical neutral radicals are used for etching, it can jump into the wafer from a random direction due to a collision with the molecules in the air.Therefore, in addition to the etching in the depth direction, ...
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Reactive ion etching is one of the microscopic techniques classified as dry etching.For applications that require ultra -fine processing such as LSI, anisotropic etching, which can be etched only in the depth direction according to the dimensions of the mask, is indispensable.This can be realized by incident the radicals required for etching vertically.There are not only neutral radicals in plasma, but also many ionized radicals.Ion exercises in the direction of the electric field if it is not scattered by an atoms or molecules.Reactive ion etching uses this property.
I will explain the principle of Rie.As introduced in the second round, there is almost no potential difference between the plasma on the anche side in the DC glow discharge, and conversely, a large voltage is applied near the cathode.Therefore, in the plasma CVD, the board is placed on the anode side so that high -speed ions do not cause defects in the film in the film formation.On the other hand, RIE puts a substrate on the cathode side to actively use ion directions.In general, RF discharge (CCP) using a parallel flat plate electrode is generally used as an etching device.In that case, the ground electrode corresponds to the anche, and the electrode that applies the RF voltage corresponds to the cathode.Here, detailed explanations are omitted.If you are interested, please refer to the literature "Plasma Semiconductor Process Engineering" Komi Ichikawa and others, Uchida Otsuru, 2003, Chapter 2.
Although it is possible to etch with several 10 nm width in RIE, there is a limit to digging a thin and deep etching shape vertically just by the direction of ions, so a method called Deep Rie has been developed.This is also called a Bosch process because it was developed by BOSCH, Germany in the early 1990s.In this method, the high aspect ratio is performed by repeating the RIE and the film deposits alternately.For example, it is also possible to open a penetrating hole with a diameter of several μm in a SI wafer with a thickness of 100 μm.Figure 3 shows the principle diagram.
図3：BoschプロセスによるDeep RIEの原理エッチングガスである六フッ化硫黄(SF6)を放電させると、プラズマ中で解離されてFやF+が生成され、これによりSiは……
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Attempts to divert the Si semiconductor -made technology and create a micro machine that combines electrical function and mechanical structure has begun around 1970.This device is called MEMS (Micro Electromechanical Systems).The typical size is about μm to mm, which is about the same as the thickness of human hair.Figure 4 shows an example of MEMS.
図4：Si基板上に作製された歯車とチェーン(引用：Sandia National Laboratories.https://www.sandia.gov/media/NewsRel/NR2002/chain.htm)Currently, MEMS is used in wide fields such as sensors, actuators, and vibration power generation.Even if you take one smartphone, some MEMS, such as acceleration sensors, gyro sensors, and microfons, are incorporated in them, and everyone uses them without being aware of it.The most important processing technology for making these MEMS is etching technology.Above all, Rie and Deep Rie are ...
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5th: Surface treatment technology
Last time, I explained the etching technology unique to plasma.This time, I will explain by spotting the surface modification of the material by plasma.Plasma processing has become an important technology in improving the surface curing of metal and the adhesive and paintability of resin materials.In addition to the outline of these technologies, we will introduce the principle of low -temperature and pressure plasma jets, which are expected to be a new plasma source suitable for these processing.
プラズマ処理とは、プラズマを用いて材料表面の洗浄や改質、コーティングなどの処理をすることです。機械装置の軸受など、回転部品に用いる鋼材（鉄鋼やステンレスなど）には、耐摩耗性が要求されます。しかし、通常の鋼材では表面硬度が十分ではないので、炭素Cや窒素Nを取り込むことで表面を硬化させる手法が用いられています。例えば、表面を炭化する方法としては、数100℃に熱したメタンCH4などのガス雰囲気中で数10時間処理する「ガス浸炭法」が古くから用いられていたものの、処理時間が長く浸炭むらがあり、ステンレス鋼に使えないといった欠点がありました。
これらの欠点を克服すべく登場したのがプラズマです。まず、処理する鋼材を真空容器に入れ、減圧してCH4などの炭素を含むガスを流します。次に、鋼材を陰極にしてグロー放電を生成すると、プラズマ中で発生した炭素を含むイオンやラジカルが鋼材に取り込まれ、表面からの炭化が効率よく進みます。特にイオンは、……
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A low temperature plasma jet is a low -temperature plasma jet generated in atmospheric pressure. The mainstream of plasma, which has been introduced so far, supplies gas into vacuum containers and discharges under reduced pressure. These devices are essential for those that dislike contamination, such as semiconductors, or that require high uniformity of film thickness and membrane in the surface. However, trying to handle large and three -dimensional materials can cause various restrictions in vacuum devices. If there is a device that can irradiate plasma under the air pressure like a spray gun, the application for plasma processing will be greatly expanded. So how can such a device be realized? The hint is the barrier discharge introduced in the second time. He explained that a barrier discharge can generate a low -temperature non -equilibrium plasma even at air pressure. With this discharge, you can create a stable and easy -to -handle plasma source.
まず、Paschen（パッシェン）の法則から説明を始めます。パッシェンの法則とは、火花放電が起こる電圧（火花電圧）に関する法則です。間隔dの平行平板電極に電圧を印加して放電させた時の絶縁破壊電圧（放電開始電圧）VBは、ガス圧をpとするとpdの関数となり、図2に示したようなカーブで表されます。VBが最小になるpdの値は1～10(Torr･cm)（ガスにより異なります）となり、大気圧（760Torr）の場合でも、dを1mm以下にするとpdの値は数10Torr･cm以下になり、VBは数100Vになります。このように、大気圧でも放電空間を小さくすれば、比較的低電圧で放電が起こります。
図2：種々のガスにおける放電開始電圧（VB）とpd（p：ガス圧、d：電極間隔）の関係Based on this principle ...
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Around our body, plastic (synthetic resin) products made of polymer materials are overflowing.However, when commercializing, the process of painting and adhesion is indispensable.Plasma is active in such a case.For example, a car bumper is commonly used in resin called polypropylene.When this resin is molded, a low -polymerization layer called WBL (WeakBoundary Layer) is formed on the surface.Due to this layer, problems such as paint difficulty and difficult to adhere occur.For this reason, in the past, dry surface treatments such as wet surface treatment using acid and alkali, UV ozone irradiation and flame (frame) treatment have been used for the purpose of surface modification of polymer material.
In the plasma, as we have introduced so far, it is possible to easily generate excitation activity such as radicals and ions.Therefore, research using plasma was conducted for these processing.It was found that a very short plasma irradiation improves hydrophilicity, printing, adhesive, and paintability of the resin surface without affecting the bulk characteristics of the material.The following three items are given by plasma on the polymer surface.
Due to active species such as radicals and ions generated in plasma, cleaning organic pollutants on the surface of plastic and removing WBL.
When the plasma is irradiated, the resin surface is applied to the electrons, and ...
>>第5回 第3章の続きを読む（PDFダウンロード）
6th: Application to biotechnology
Last time, I explained the surface treatment technology of plasma.This time, I will explain the bio technical application of plasma.The appearance of a low -temperature plasma that can be easily handled with the air pressure introduced last time has brought paradigm shift to biotechnology, and new knowledge has been obtained one after another.The application of plasma to biotechnology is still in a short history of research, and it is complicated for living things, and there are many events that the mechanism has not been fully elucidated.Nevertheless, since it is the most notable field, here are some examples at the end of the series.
低温大気圧プラズマジェットは、生体への照射が可能なことから、バイオ技術との相性がよい画期的なプラズマ源です。これまで紹介したように、プラズマ中では高速電子や励起分子、ラジカルが発生します。そして、このプラズマジェットを大気中で生体に照射すると、下流域で空気を巻き込むため、これらの粒子と空気、および空気中の水蒸気が反応し、活性酸素種（Reactive Oxygen Species：ROS）や活性窒素種（Reactive Nitrogen Species：RNS）と呼ばれる、生体に影響を与える活性種が効率よく生成されます。ROSには、原子状酸素（O）、オゾン（O3）、ヒドロキシラジカル（OH）、過酸化水素（H2O2）など、RNSには一酸化窒素（NO）、二酸化窒素（NO2）、亜酸化窒素（N2O）などが含まれます。
Research since 2000 has shown that irradiating plasma, such as active species, charging particles supplied from plasma, ultraviolet light, etc., have various effects on living cells and crops.I did it.There are still many events that have not been fully elucidated, even for detailed mechanisms, because the research target is a living body and the history of the research itself is shallow.However, there are many interesting results that can be expected for future progress.Here are the medical and agricultural applications of plasma (Fig. 1).
図1：低温大気圧プラズマの応用Plasma medicine is to use plasma to directly treat human cells.Applications for plasma to medical care include sterilization of medical equipment, cancer treatment, hemostasis, gene introduction to cells, immunotherapy, and wound treatment (Fig. 2).
図2：プラズマ医療の応用The first thing that is taken up for medical treatment is sterilization of medical equipment due to plasma irradiation.By directly irradiating the plasma jet to bacteria, viruses, mold, etc. ...
>>第6回 第2章の続きを読む（PDFダウンロード）
Research is progressing rapidly for the application of plasma in agriculture. The effects of plasma irradiation have been reported to promote growth and disinfect crops. Vegetable production in plant factories, which can be expected to have high productivity, is expected to become more and more popular. And there is widely used hydroponic cultivation, which circulates nutrients without using soil. This cultivation method has the advantage that pesticides are unnecessary, but if some seedlings cause illness, there is a drawback that other seedlings may spread through the recycling solution, which can cause catastrophic damage. 。 In order to avoid this, sterilization of nutrition is important. Therefore, it was confirmed that if the plasma was irradiated with the nutrient, the nutrients had a powerful bactericidal effect of killing bacteria and mold. It has also been confirmed that nitrogen is supplied to solution as a nutrient due to the effects of ROS and RNS.
作物の成長促進においても、プラズマ照射が興味深い効果を及ぼすことが確認されています。例えば、かいわれ大根の種にO2プラズマを照射すると……
>>第6回 第3章の続きを読む（PDFダウンロード）