HfO_x鑲嵌結(jié)構(gòu)的CMP及其機(jī)理研究
發(fā)布時(shí)間：2018-09-17 08:02
【摘要】：過渡金屬氧化物材料氧化鉿(Hf Ox)以其優(yōu)異的性能而被廣泛應(yīng)用于微電子器件和光電子器件等領(lǐng)域,同時(shí),相關(guān)的高性能器件對(duì)疊層材料的表面和界面也提出了極高的要求。在IC領(lǐng)域中,既能保證疊層材料的全局平坦化,又能實(shí)現(xiàn)器件的互連鑲嵌結(jié)構(gòu)的唯一技術(shù)就是化學(xué)機(jī)械平坦化(CMP)。作為下一代非揮發(fā)性存儲(chǔ)器(NVM)最有力的競(jìng)爭(zhēng)者之一的阻變存儲(chǔ)器(RRAM)必須完成高密度高集成才可彰顯其優(yōu)勢(shì),因此,存儲(chǔ)功能材料及相關(guān)電極材料的平坦化技術(shù)成為RRAM產(chǎn)業(yè)化推進(jìn)的關(guān)鍵所在(ITRS-2005已經(jīng)預(yù)測(cè)了NVM中的平坦化技術(shù)是不可或缺的關(guān)鍵工藝)。Hf Ox基RRAM被業(yè)界預(yù)測(cè)為最有可能或最早實(shí)現(xiàn)產(chǎn)業(yè)化的阻變器件之一,本論文針對(duì)Hf Ox基NVM器件制作過程中的關(guān)鍵工藝——CMP,開展了研究。主要研究了拋光液組分和拋光工藝參數(shù)對(duì)裸片和帶通孔結(jié)構(gòu)的Hf Ox-CMP的影響;結(jié)合AFM和FTIR等測(cè)試表征,對(duì)Hf Ox-CMP機(jī)理進(jìn)行了初步探索;并基于Hf Ox-CMP工藝的優(yōu)化制作了鑲嵌(通孔)結(jié)構(gòu)的阻變器件。本文首先通過p H值、添加劑Na BF4濃度和磨料粒徑對(duì)拋光液進(jìn)行了優(yōu)化,從拋光速率、表面均方根(RMS)粗糙度以及拋光液穩(wěn)定性方面進(jìn)行了綜合評(píng)判,發(fā)現(xiàn)當(dāng)p H=6時(shí),利用39.9nm的Si O2磨料在含0.2wt%-Na BF4的拋光液中對(duì)Hf Ox薄膜進(jìn)行拋光,拋光速率可達(dá)70.1nm/min,拋光后表面粗糙度可達(dá)0.3nm,同時(shí)對(duì)Si O2的拋光選擇比大于10;其次,利用最佳拋光液工藝參數(shù),研究了拋光下壓力和拋光盤轉(zhuǎn)速對(duì)材料去除速率和表面粗糙度的影響,隨著下壓力和拋光盤轉(zhuǎn)速的增大,Hf Ox的拋光速率成線性增加,符合Preston方程,但對(duì)表面粗糙度影響不大;同時(shí),還對(duì)不同尺寸通孔經(jīng)Hf Ox-CMP后形成的dishing情況進(jìn)行了研究,發(fā)現(xiàn)當(dāng)通孔尺寸由3μm增大至9μm時(shí),dishing由19.80nm增加至60.85nm,但不同通孔dishing分布的離散性無較大變化。接著,在Hf Ox-CMP工藝研究的基礎(chǔ)上,對(duì)其拋光機(jī)理進(jìn)行了探索,一方面,根據(jù)對(duì)拋光下壓力與拋光盤轉(zhuǎn)速乘積的擬合,對(duì)Preston方程進(jìn)行了修訂:cRR?k PV?R,根據(jù)擬合結(jié)果得出截距Rc(5.58nm/min)與實(shí)驗(yàn)中Hf Ox腐蝕速率(~5.2nm/min)基本一致,因此將其定義為Hf Ox的靜態(tài)腐蝕速率;另一方面,利用AFM和FTIR對(duì)拋光前后和經(jīng)Na BF4溶液腐蝕前后的Hf Ox薄膜表面進(jìn)行了表征,發(fā)現(xiàn)在拋光過程中有表面層的生成,軟化了Hf Ox表面,促進(jìn)了拋光的進(jìn)行。結(jié)合以上兩方面的分析,初步探索出Hf Ox的拋光機(jī)理為:Hf Ox薄膜首先與添加劑Na BF4反應(yīng)生成硬度相對(duì)較小的表面層,接著在磨料機(jī)械磨削作用下,表面層被去除,兩步過程交替進(jìn)行完成對(duì)Hf Ox薄膜的拋光。最后,基于對(duì)Hf Ox-CMP工藝的優(yōu)化和機(jī)理的分析,制作了通孔結(jié)構(gòu)的Hf Ox基阻變器件,進(jìn)行了電學(xué)性能的測(cè)試,并與無結(jié)構(gòu)阻變器件進(jìn)行了對(duì)比。結(jié)果表明:通孔結(jié)構(gòu)阻變器件具有較小的Set電壓、較小的Set電壓和高低阻態(tài)分布的離散性,并且,通孔結(jié)構(gòu)阻變器件cell間Set電壓的一致性更好,分布更為集中。由此可判斷,本論文針對(duì)Hf Ox-CMP工藝的優(yōu)化和研究在器件制作過程中是有效的,也是可行的,為進(jìn)一步提高阻變器件的一致性提供了方案和實(shí)驗(yàn)基礎(chǔ)。
[Abstract]:Transition metal oxide material hafnium oxide (Hf Ox) is widely used in microelectronic devices and optoelectronic devices because of its excellent properties. At the same time, the related high-performance devices also put forward very high requirements for the surface and interface of the laminated materials. In IC field, it can not only ensure the overall flatness of the laminated materials, but also realize the device. Chemical mechanical flattening (CMP) is the only technology for interconnect mosaic structures. Resistive memory (RRAM), one of the most powerful competitors for the next generation of non-volatile memory (NVM), must have high density and high integration to demonstrate its advantages. Therefore, the flattening technology of storage functional materials and related electrode materials has become the industrialization of RRAM. Hf Ox-based RRAM has been predicted to be one of the most likely or earliest resistance devices to be industrialized. In this paper, CMP, the key technology in the fabrication of Hf Ox-based NVM devices, is studied. The influence of processing parameters on Hf Ox-CMP of bare wafer and through-hole structure was studied. The mechanism of Hf Ox-CMP was explored by combining the characterization of AFM and FTIR. Resistance devices with mosaic (through-hole) structure were fabricated based on the optimization of Hf Ox-CMP process. Firstly, the effect of P H value, concentration of additive Na BF4 and abrasive particle size on the polishing fluid was studied. The polishing rate, surface RMS roughness and the stability of polishing solution were optimized. It was found that the polishing rate of Hf Ox film in 0.2wt%-Na BF4 polishing solution with 39.9nm Si O2 abrasive was 70.1nm/min, and the surface roughness was 0.3nm after polishing. Secondly, the influence of polishing pressure and disc rotational speed on material removal rate and surface roughness was studied by using the optimum polishing fluid parameters. With the increase of downward pressure and disc rotational speed, the polishing rate of Hf Ox increased linearly, which accorded with Preston equation, but had little effect on surface roughness. The dishing of through holes with different sizes after Hf Ox-CMP was studied. It was found that the dishing increased from 19.80 nm to 60.85 nm when the size of through holes increased from 3 to 9 microns, but the dispersion of dishing distribution in different through holes did not change much. Then, the polishing mechanism was explored on the basis of Hf Ox-CMP process research. According to the fitting of the product of polishing pressure and rotational speed of polishing disc, the Preston equation was revised: cRR? K PV? R. According to the fitting results, the intercept Rc (5.58 nm/min) was basically consistent with the experimental Hf Ox corrosion rate (~5.2 nm/min), so it was defined as the static corrosion rate of Hf Ox; on the other hand, the static corrosion rate of Hf Ox before and after polishing and Na after polishing was determined by AFM and FTIR. The surface of Hf Ox film was characterized before and after corrosion by BF4 solution. It was found that there was a surface layer formed during the polishing process, which softened the surface of Hf Ox and promoted the polishing process. Then, the surface layer is removed by abrasive mechanical grinding, and the Hf Ox film is polished by two steps alternately. Finally, based on the optimization of Hf Ox-CMP process and the analysis of mechanism, the Hf Ox resistive devices with through-hole structure are fabricated, and the electrical properties are tested and compared with the unstructured resistive devices. Ming: The through-hole resistive devices have smaller Set voltage, smaller Set voltage and discrete distribution of high and low resistance states. Moreover, the through-hole resistive devices have better consistency and more concentrated distribution of Set voltage between cells. It provides a feasible and experimental basis for further improving the consistency of resistive devices.
【學(xué)位授予單位】：天津理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN305.2
本文編號(hào)：2245241
[Abstract]:Transition metal oxide material hafnium oxide (Hf Ox) is widely used in microelectronic devices and optoelectronic devices because of its excellent properties. At the same time, the related high-performance devices also put forward very high requirements for the surface and interface of the laminated materials. In IC field, it can not only ensure the overall flatness of the laminated materials, but also realize the device. Chemical mechanical flattening (CMP) is the only technology for interconnect mosaic structures. Resistive memory (RRAM), one of the most powerful competitors for the next generation of non-volatile memory (NVM), must have high density and high integration to demonstrate its advantages. Therefore, the flattening technology of storage functional materials and related electrode materials has become the industrialization of RRAM. Hf Ox-based RRAM has been predicted to be one of the most likely or earliest resistance devices to be industrialized. In this paper, CMP, the key technology in the fabrication of Hf Ox-based NVM devices, is studied. The influence of processing parameters on Hf Ox-CMP of bare wafer and through-hole structure was studied. The mechanism of Hf Ox-CMP was explored by combining the characterization of AFM and FTIR. Resistance devices with mosaic (through-hole) structure were fabricated based on the optimization of Hf Ox-CMP process. Firstly, the effect of P H value, concentration of additive Na BF4 and abrasive particle size on the polishing fluid was studied. The polishing rate, surface RMS roughness and the stability of polishing solution were optimized. It was found that the polishing rate of Hf Ox film in 0.2wt%-Na BF4 polishing solution with 39.9nm Si O2 abrasive was 70.1nm/min, and the surface roughness was 0.3nm after polishing. Secondly, the influence of polishing pressure and disc rotational speed on material removal rate and surface roughness was studied by using the optimum polishing fluid parameters. With the increase of downward pressure and disc rotational speed, the polishing rate of Hf Ox increased linearly, which accorded with Preston equation, but had little effect on surface roughness. The dishing of through holes with different sizes after Hf Ox-CMP was studied. It was found that the dishing increased from 19.80 nm to 60.85 nm when the size of through holes increased from 3 to 9 microns, but the dispersion of dishing distribution in different through holes did not change much. Then, the polishing mechanism was explored on the basis of Hf Ox-CMP process research. According to the fitting of the product of polishing pressure and rotational speed of polishing disc, the Preston equation was revised: cRR? K PV? R. According to the fitting results, the intercept Rc (5.58 nm/min) was basically consistent with the experimental Hf Ox corrosion rate (~5.2 nm/min), so it was defined as the static corrosion rate of Hf Ox; on the other hand, the static corrosion rate of Hf Ox before and after polishing and Na after polishing was determined by AFM and FTIR. The surface of Hf Ox film was characterized before and after corrosion by BF4 solution. It was found that there was a surface layer formed during the polishing process, which softened the surface of Hf Ox and promoted the polishing process. Then, the surface layer is removed by abrasive mechanical grinding, and the Hf Ox film is polished by two steps alternately. Finally, based on the optimization of Hf Ox-CMP process and the analysis of mechanism, the Hf Ox resistive devices with through-hole structure are fabricated, and the electrical properties are tested and compared with the unstructured resistive devices. Ming: The through-hole resistive devices have smaller Set voltage, smaller Set voltage and discrete distribution of high and low resistance states. Moreover, the through-hole resistive devices have better consistency and more concentrated distribution of Set voltage between cells. It provides a feasible and experimental basis for further improving the consistency of resistive devices.
【學(xué)位授予單位】：天津理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN305.2
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