雙脈沖電場伏安特性對純Ti薄膜結(jié)構(gòu)及性能的影響
發(fā)布時間：2018-12-13 19:15
【摘要】：針對磁控濺射離子鍍沉積粒子離化率低而造成的薄膜均勻性差等技術(shù)不足,依據(jù)等離子體物理學(xué)中氣體放電伏安特性曲線中存在一強(qiáng)輝弱弧區(qū)間,探討了強(qiáng)輝弱弧區(qū)間磁控陰極電場模式對純金屬Ti薄膜微觀結(jié)構(gòu)及性能的影響規(guī)律和可調(diào)控范圍,以可觀察的微觀組織和可測的硬度等性能指標(biāo)為依據(jù),揭示了難以直接觀察的陰極靶面沉積粒子瞬態(tài)脫靶方式隨電場模式的演變規(guī)律,并通過對脫靶方式的調(diào)控以提高沉積粒子離化率。實驗通過在陰極靶材與陽極腔體間構(gòu)建具有較大電流密度和較強(qiáng)電場強(qiáng)度的高功率脈沖及雙脈沖電場將氣體放電引入強(qiáng)輝弱弧區(qū)間,借助Ar+轟擊靶材產(chǎn)生的能量累積和靶材內(nèi)電子傳輸產(chǎn)生的焦耳熱積累,使沉積粒子因靶面溫度迅速上升而引起大量的熱發(fā)射,即實現(xiàn)了沉積粒子以碰撞增強(qiáng)熱發(fā)射方式脫靶,并以此改善沉積薄膜的微觀結(jié)構(gòu)及綜合性能。研究表明:在相同平均功率條件下,直流電場峰值電流密度處于較小值為0.04A/cm2,氣體放電處于輝光區(qū),薄膜表現(xiàn)出疏松、致密性差的結(jié)構(gòu),晶粒尺寸為28nm,表面粗糙度為127 nm,由此表明碰撞脫靶難以獲得高能量、高離化率的沉積粒子導(dǎo)致薄膜性能較差。當(dāng)采用高功率脈沖及雙脈沖電場時,均可獲得大于0.5 A/cm2的峰值電流密度,并且根據(jù)測得的電流密度達(dá)到0.2 A/cm2時氣體放電進(jìn)入反歐姆區(qū),說明脈沖電場環(huán)境可將氣體放電引入強(qiáng)輝弱弧區(qū),實現(xiàn)了由Ar+單純碰撞脫靶機(jī)制向Ar+碰撞和靶材熱發(fā)射兩種脫靶機(jī)制的混合脫靶方式的轉(zhuǎn)變。沉積的薄膜表現(xiàn)出致密的結(jié)構(gòu),晶粒尺寸在20nm以內(nèi),粗糙度在20 nm左右。并且雙脈沖電場平均沉積薄膜速率45.7 nm/min,約為高功率脈沖的2倍且接近直流的沉積速率,在靶基距240mm處薄膜最厚為1.496μm,正反厚度比為2.51最接近于1,說明碰撞增強(qiáng)熱發(fā)射脫靶方式能夠獲得離化率及能量均較高的沉積粒子,從而改善了真空腔內(nèi)沉積粒子分布的均勻性,并且薄膜具有致密的微觀結(jié)構(gòu)、優(yōu)異的膜基結(jié)合強(qiáng)度及力學(xué)性能等。通過對雙脈沖電場中不同峰值靶電流密度下沉積的薄膜結(jié)構(gòu)與性能的研究發(fā)現(xiàn),隨著峰值電流密度的增加,薄膜在近靶處與遠(yuǎn)靶處的厚度差越來越小,最小達(dá)到1.4μm,沿靶基距方向的厚度減小率也從90 %降至77.8 %,正反厚度比最小為1.91。通過縮短脈沖開通時間,不但峰值電流密度增加,而且單脈沖內(nèi)有足夠的停頓時間使高活性和擴(kuò)散能的沉積粒子在基片表面沉積成膜。隨著靶峰值電流密度的增加,薄膜微觀形貌越來越平整致密,在峰值電流密度為1.35 A/cm2時,劃痕測試臨界載荷最高達(dá)到13.7 N且劃痕整體未出現(xiàn)斷裂剝落現(xiàn)象,硬度及彈性模量最大分別為5.625 GPa和165.380 GPa,NaCl腐蝕溶液中的腐蝕速率僅為1.9655x10-4mm/a。最終,通過構(gòu)建新型雙脈沖電場及對其電流密度的調(diào)控可獲得結(jié)構(gòu)致密,性能優(yōu)異的薄膜。
[Abstract]:In view of the lack of uniform film due to the low ionization rate of ion plating deposited by magnetron sputtering, there is a strong and weak arc region in the volt-ampere characteristic curve of gas discharge in plasma physics. The influence of the mode of magnetic controlled cathode electric field on the microstructure and properties of pure metal Ti thin films is discussed in the range of strong glow and weak arc. The controllable range is based on the observable microstructure and measurable hardness. The evolution law of transient miss mode with electric field mode of deposited particles on cathode target surface which is difficult to observe directly is revealed and the ionization rate of deposited particles is improved by adjusting the miss mode. In this experiment, high power pulse and double pulse electric field with high current density and strong electric field intensity were constructed between cathode target and anode cavity to introduce gas discharge into strong glow and weak arc region. With the energy accumulation generated by Ar bombarding the target material and the Joule heat accumulation caused by electron transport in the target material, a large amount of heat emission is caused by the rapid rise of the target surface temperature, that is, the deposition particles miss the target by collision enhanced heat emission. The microstructure and comprehensive properties of the deposited films are improved. The results show that under the same average power, the peak current density of DC field is 0.04A / cm ~ 2, the gas discharge is in the glow region, the thin film exhibits loose structure and poor compactness, and the grain size is 28 nm. The surface roughness is 127 nm, which indicates that the collision miss is difficult to obtain high energy, and the high ionization rate of the deposited particles leads to the poor performance of the film. When the high power pulse and double pulse electric field are used, the peak current density of more than 0.5 A/cm2 can be obtained, and the gas discharge enters the anti-ohmic region according to the measured current density of 0.2 A/cm2. It is shown that the gas discharge can be introduced into the strong glow and weak arc region in the environment of pulsed electric field, and the mixed miss mode can be changed from the pure collision mechanism of Ar to the two mechanisms of Ar collision and hot emission of target materials. The deposited films exhibit dense structure with grain size within 20nm and roughness of about 20 nm. The average deposition rate of double pulse electric field is 45.7 nm/min, which is about 2 times of that of high power pulse and close to DC. The film thickness is 1.496 渭 m at the target substrate distance from 240mm, and the ratio of positive and negative thickness is close to 1. The results show that collision enhanced thermal emission miss mode can obtain deposited particles with higher ionization rate and higher energy, thus improving the uniformity of particle distribution in the vacuum cavity, and the film has a compact microstructure. Excellent bonding strength and mechanical properties. The structure and properties of the films deposited at different peak current densities in a double-pulse electric field are studied. It is found that with the increase of the peak current density, the thickness difference between the near target and the distant target becomes smaller and smaller, and the minimum is 1.4 渭 m. The decrease rate of the thickness along the distance direction of the target is also reduced from 90% to 77.8%, and the minimum ratio of positive and negative thickness is 1.91. By shortening the pulse opening time, not only the peak current density is increased, but also there is enough pause time in the monopulse to make the highly active and diffusive particles deposited on the substrate surface. With the increase of the target peak current density, the microcosmic morphology of the film becomes more and more smooth and compact. When the peak current density is 1.35 A/cm2, the critical load of scratch test reaches 13.7 N and the whole scratch does not appear fracture and spalling phenomenon. The maximum hardness and modulus of elasticity are 5.625 GPa and 165.380 GPa,NaCl respectively. The corrosion rate is only 1.9655 x 10-4 mm / a. Finally, the thin films with dense structure and excellent performance can be obtained by constructing a new type of double-pulse electric field and regulating its current density.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG174.4
[Abstract]:In view of the lack of uniform film due to the low ionization rate of ion plating deposited by magnetron sputtering, there is a strong and weak arc region in the volt-ampere characteristic curve of gas discharge in plasma physics. The influence of the mode of magnetic controlled cathode electric field on the microstructure and properties of pure metal Ti thin films is discussed in the range of strong glow and weak arc. The controllable range is based on the observable microstructure and measurable hardness. The evolution law of transient miss mode with electric field mode of deposited particles on cathode target surface which is difficult to observe directly is revealed and the ionization rate of deposited particles is improved by adjusting the miss mode. In this experiment, high power pulse and double pulse electric field with high current density and strong electric field intensity were constructed between cathode target and anode cavity to introduce gas discharge into strong glow and weak arc region. With the energy accumulation generated by Ar bombarding the target material and the Joule heat accumulation caused by electron transport in the target material, a large amount of heat emission is caused by the rapid rise of the target surface temperature, that is, the deposition particles miss the target by collision enhanced heat emission. The microstructure and comprehensive properties of the deposited films are improved. The results show that under the same average power, the peak current density of DC field is 0.04A / cm ~ 2, the gas discharge is in the glow region, the thin film exhibits loose structure and poor compactness, and the grain size is 28 nm. The surface roughness is 127 nm, which indicates that the collision miss is difficult to obtain high energy, and the high ionization rate of the deposited particles leads to the poor performance of the film. When the high power pulse and double pulse electric field are used, the peak current density of more than 0.5 A/cm2 can be obtained, and the gas discharge enters the anti-ohmic region according to the measured current density of 0.2 A/cm2. It is shown that the gas discharge can be introduced into the strong glow and weak arc region in the environment of pulsed electric field, and the mixed miss mode can be changed from the pure collision mechanism of Ar to the two mechanisms of Ar collision and hot emission of target materials. The deposited films exhibit dense structure with grain size within 20nm and roughness of about 20 nm. The average deposition rate of double pulse electric field is 45.7 nm/min, which is about 2 times of that of high power pulse and close to DC. The film thickness is 1.496 渭 m at the target substrate distance from 240mm, and the ratio of positive and negative thickness is close to 1. The results show that collision enhanced thermal emission miss mode can obtain deposited particles with higher ionization rate and higher energy, thus improving the uniformity of particle distribution in the vacuum cavity, and the film has a compact microstructure. Excellent bonding strength and mechanical properties. The structure and properties of the films deposited at different peak current densities in a double-pulse electric field are studied. It is found that with the increase of the peak current density, the thickness difference between the near target and the distant target becomes smaller and smaller, and the minimum is 1.4 渭 m. The decrease rate of the thickness along the distance direction of the target is also reduced from 90% to 77.8%, and the minimum ratio of positive and negative thickness is 1.91. By shortening the pulse opening time, not only the peak current density is increased, but also there is enough pause time in the monopulse to make the highly active and diffusive particles deposited on the substrate surface. With the increase of the target peak current density, the microcosmic morphology of the film becomes more and more smooth and compact. When the peak current density is 1.35 A/cm2, the critical load of scratch test reaches 13.7 N and the whole scratch does not appear fracture and spalling phenomenon. The maximum hardness and modulus of elasticity are 5.625 GPa and 165.380 GPa,NaCl respectively. The corrosion rate is only 1.9655 x 10-4 mm / a. Finally, the thin films with dense structure and excellent performance can be obtained by constructing a new type of double-pulse electric field and regulating its current density.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG174.4
【參考文獻(xiàn)】
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