WO2015184573A1

WO2015184573A1 - Ultra-low dielectric constant insulating film and method for manufacturing same

Info

Publication number: WO2015184573A1
Application number: PCT/CN2014/000708
Authority: WO
Inventors: 丁士进; 丁子君; 张卫
Original assignee: 复旦大学
Priority date: 2014-06-04
Filing date: 2014-07-28
Publication date: 2015-12-10
Also published as: CN104008997A

Abstract

An ultra-low dielectric constant insulating film and a method for manufacturing same are disclosed. The method comprises: step 1, depositing a thin film by a technology of plasma enhance chemical vapor deposition, MTES and LIMO used as reaction source and helium used as carrier gas being led into a chemical vapor deposition reaction cavity, wherein, the insulating film formed by deposition has a thickness of 50-100 nm, and the flow ratio of the MTES and the LIMO is equal to 1:1 - 1:2.5; step 2, conducting in-situ remediation on the surface of the insulating layer by using Ar plasma to form a compact modified layer; step 3, repeating step 1 and step 2 to obtain the insulating film of target thickness; step 4, annealing the insulation film at high temperature to form ultra-low dielectric constant insulating film. Alternative plasma used for enhancing the chemical vapor deposition of the insulating film and post-plasma processing are creatively used in the invention with simply process and good deposition rate, the formed film has good moisture resistance and is compatible with integrated technique, the film forming quality is good, and the needs of advanced integrated circuit for electrical property, mechanical property and insulation property of low dielectric constant material are fully satisfied.

Description

一种超低介电常数绝缘薄膜及其制备方法 Ultra-low dielectric constant insulating film and preparation method thereof

技术领域本发明属于超大规模集成电路（ULSI)互连技术领域，具体为用于填充互连金属层之间的低介电常数绝缘薄膜的制备方法。背景技术随着器件尺寸不断减小到深亚微米，就要求采用多层互连结构，以使由于寄生电阻（R)和电容（C)而产生的延时最小化。由于 RC延时的增加，在栅上获得的器件速度的增益被金属互连线之间的传播延时所抵消；参见刘鸣，刘玉玲，刘博等."低 k介质与铜互连集成工艺". [J].《微纳电子技术》， 2006, 10(6)： 464-469 为了减小 ULSI电路中的 RC常数，需要互连材料具有低电阻率和膜层间的低电容。众所周知， C = /d ,其中是介电常数， A 为面积， d为电介质膜层厚度，介电长数等于 k和 _ε。的乘积， εο为真空的介电常数， k为相对介电常数。考虑低电容情况，通过增加介电层膜厚（引起间隙填充更困难）或减小导线厚度和面积（导致电阻增加）来降低寄生电容是更不容易的。所以，这就要求材料有更低的介电常数，由此产生对低介电常数材料的需求。 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of ultra-large scale integrated circuit (ULSI) interconnect technology, and more particularly to a method for fabricating a low dielectric constant insulating film between interconnect metal layers. BACKGROUND OF THE INVENTION As device dimensions continue to decrease to deep submicron, multilayer interconnect structures are required to minimize delays due to parasitic resistance (R) and capacitance (C). Due to the increase in RC delay, the gain of the device speed obtained on the gate is offset by the propagation delay between the metal interconnects; see Liu Ming, Liu Yuling, Liu Bo et al. "Low-k dielectric and copper interconnect integration process [J]. Micro-Nano Electronic Technology, 2006, 10(6): 464-469 In order to reduce the RC constant in ULSI circuits, interconnect materials are required to have low resistivity and low capacitance between layers. It is well known that C = /d, where is the dielectric constant, A is the area, d is the thickness of the dielectric film, and the dielectric length is equal to k and _ε . The product of εο is the dielectric constant of vacuum and k is the relative dielectric constant. Considering the low capacitance case, it is not easy to reduce the parasitic capacitance by increasing the dielectric layer film thickness (which makes the gap filling more difficult) or reducing the wire thickness and area (resulting in an increase in resistance). Therefore, this requires a material having a lower dielectric constant, thereby resulting in a need for a low dielectric constant material.

超大规模集成电路不断发展，要求采用介电常数更低的材料即 k<2.6的介质薄膜，然而材料的介电常数主要与材料的总极化率以及材料的密度相关，目前获得超低介电常数材料主要是通过在介质基体中引入孔隙（介电常数约等于 1 )来实现的，这主要因为引入孔隙可以有效降低材料本身的密度。根据国内外的文献（如， Miller R.D.米勒 R.D.等 In search of low-k dielectrics, 低 -k介电常数的研究 [J]. ((Science科学》 , 1999, 286 (5439) : 421-423 )及中国专利（丁士进等， "一种多孔超低介电常数材料薄膜及其制备方法"，公开号 CN 101789418 A)报道，多孔薄膜材料中的孔隙通常是在前驱体中添加模板剂，再通过热处理方法除去模板剂，从而获得多孔薄膜材料。此方法例如， Shen等人以正硅酸乙酯（TEOS )为硅源，十六垸基三甲基溴化铵（CTAB) 为模板剂，在酸性条件下采用溶胶凝胶方法制备出多孔薄膜材料，孔径为 4nm，介电常数为 2.5 (参考文献 J. Shen, A. Luo, L. F. Yao, et al. Low dielectric constant silica films with ordered nanoporous structure [J]. Materials science and Engineering, 2007，27(5-8):1145-1148)。但是上述专利 "一种多孔超低介电常数材料薄膜及其制备方法"中提到的低介电常数薄膜的制备方法为旋涂 The development of very large scale integrated circuits requires the use of a material with a lower dielectric constant, that is, a dielectric film of k < 2.6. However, the dielectric constant of the material is mainly related to the total polarizability of the material and the density of the material, and ultra-low dielectric is currently obtained. The constant material is mainly achieved by introducing pores in the dielectric matrix (dielectric constant is approximately equal to 1), mainly because the introduction of pores can effectively reduce the density of the material itself. According to domestic and foreign literature (for example, Miller RD Miller RD and other In search of low-k dielectrics, low-k dielectric constants [J]. (Science Science, 1999, 286 (5439): 421-423 And Chinese patents (Ding Shijin et al., "A porous ultra-low dielectric constant material film and its preparation method", published in CN 101789418 A), the pores in the porous film material are usually added with a templating agent in the precursor, and then The templating agent is removed by a heat treatment method to obtain a porous film material. For example, Shen et al. used tetraethyl orthosilicate (TEOS) as a silicon source and hexadecanoyltrimethylammonium bromide (CTAB) as a template to prepare a porous film material by sol-gel method under acidic conditions. The pore diameter is 4 nm and the dielectric constant is 2.5 (Reference J. Shen, A. Luo, LF Yao, et al. Low dielectric constant silica films with ordered nanoporous structure [J]. Materials science and Engineering, 2007, 27 (5- 8): 1145-1148). However, the preparation method of the low dielectric constant film mentioned in the above patent "a porous ultra-low dielectric constant material film and a preparation method thereof" is spin coating

( spin-coating)成膜，旋涂方法制备的薄膜多存在成膜质量较差，厚度不均一等问题，因此现代大规模集成电路工艺已经基本不采用旋涂方法制备薄膜，而是采用本发明提到的等离子体增强化学气相沉积（plasma enhanced chemical vapor deposition, PECVD) 方法。相比较旋涂方法，利用 PECVD 技术制备低介电常数薄膜具有均匀性和重复性好，可大面积成膜，台阶覆盖优良。另外，薄膜成分和厚度易于控制，且使用范围广，设备简易，易于产业化，效率高且成本低。 (Spin-coating) film formation, the film prepared by the spin coating method has many problems such as poor film formation quality and uneven thickness. Therefore, the modern large-scale integrated circuit process has basically not used the spin coating method to prepare the film, but adopts the present invention. A plasma enhanced chemical vapor deposition (PECVD) method is mentioned. Compared with the spin coating method, the low dielectric constant film prepared by PECVD has good uniformity and repeatability, can form a large area film, and has excellent step coverage. In addition, the composition and thickness of the film are easy to control, and the range of use is wide, the equipment is simple, the production is easy, the efficiency is high, and the cost is low.

自从 2001年 Grill等人首次报道 PECVD技术制备出了低介电常数多孔薄膜材料以来，国际上陆续出现了相关的文献报道，如表 1所示： Since Grill et al. first reported in 2001 that PECVD technology has produced low dielectric constant porous film materials, relevant literature reports have appeared in the world, as shown in Table 1:

表 1. PECVD方法制备低介电常数多孔薄膜材料 Table 1. Preparation of low dielectric constant porous film materials by PECVD method

参考文献 5： R. Navamathavan, C. K. Choi. Plasma enhanced chemical vapor deposition of low dielectric constant SiOC(-H) films using MTES/0₂ precursor [J], Thin Solid Films, 2007, 515(12): 5040-5044. Reference 5: R. Navamathavan, CK Choi. Plasma enhanced chemical vapor deposition of low dielectric constant SiOC(-H) films using MTES/0 ₂ precursor [J], Thin Solid Films, 2007, 515(12): 5040-5044 .

参考文献 Grill Alfred. Plasma enhanced chemical vapor deposited SiCOH dielectrics: from low-k to extreme low-k interconnect materials [J], Journal of Applied Physics, 2003, 93(3): 1785-1790. References Gramine Alfred. Plasma enhanced chemical vapor deposited SiCOH dielectrics: from low-k to extreme low-k interconnect materials [J], Journal of Applied Physics, 2003, 93(3): 1785-1790.

参考文献 7： S.-K. Kwak, K.-H. Jeong, S.-W. R ee et al.， Nanocomposite Low-k SiCOH Films by Direct PECVD Using Vinyltrimethylsilane [J]. Journal of the Electrochemical Society, 2004, 151(2): F11-F16. Reference 7: S.-K. Kwak, K.-H. Jeong, S.-W. R ee et al., Nanocomposite Low-k SiCOH Films by Direct PECVD Using Vinyltrimethylsilane [J]. Journal of the Electrochemical Society, 2004, 151(2): F11-F16.

如表 1中所示文献 5和 7中报道分别采用 MTES+0₂和 VTMS+0₂为前驱体，不同温度下利用 PECVD技术沉积薄膜，最终的退火温度分别为 500°C 和 450°C，然而如此高的退火温度条件不能满足通常的集成电路后道工艺对低介电常数材料的热稳定性要求（≤420°C )。文献 6采用热处理方法去除成孔剂得到介电常数为 2.05的薄膜材料，但是力学性能不理想，很难满足工艺界对薄膜材料的要求。本发明利用具有新颖性的 MTES和 LIMO的混合前驱体，创新性地采用交替 PECVD绝缘薄膜和后等离子体处理的方法，即将绝缘层沉积步骤和致密层形成步骤交替进行，形成的薄膜具有抗吸湿性强，力学性能好，薄膜退火温度低，与集成工艺相兼容等优点。发明的公开 As shown in Table 1 in Tables 5 and 7, MTES+0 ₂ and VTMS+0 ₂ were used as precursors, respectively, and films were deposited by PECVD at different temperatures, and the final annealing temperatures were 500 ° C and 450 ° C, respectively. However, such high annealing temperature conditions do not meet the thermal stability requirements (≤ 420 ° C) of low dielectric constant materials in conventional integrated circuit processes. In the literature 6, the pore-forming agent was removed by heat treatment to obtain a film material with a dielectric constant of 2.05, but the mechanical properties were not satisfactory, and it was difficult to meet the requirements of the film industry for the film material. The invention utilizes the novel mixed precursor of MTES and LIMO, innovatively adopts alternating PECVD insulating film and post-plasma treatment method, that is, the insulating layer deposition step and the dense layer forming step are alternately performed, and the formed film has anti-hygroscopicity. Strong, good mechanical properties, low annealing temperature, compatible with integrated processes. Disclosure of invention

本发明的目的是提供一种超低介电常数绝缘薄膜的制备方法，通过该方法制备的绝缘薄膜具有理想的电学性能和力学性能，可用于极大规模集成电路互连技术领域。 SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing an ultra-low dielectric constant insulating film. The insulating film prepared by the method has ideal electrical and mechanical properties and can be used in the field of extremely large-scale integrated circuit interconnection technology.

为了达到上述目的，本发明提供了一种超低介电常数绝缘薄膜的制备方法，该方法包含如下具体步骤： In order to achieve the above object, the present invention provides a method of preparing an ultra-low dielectric constant insulating film, the method comprising the following specific steps:

步骤 1，利用等离子体增强化学气相沉积技术沉积薄膜：以甲基三乙氧基硅垸和柠檬烯为反应源，且甲基三乙氧基硅垸和柠檬烯均以氦气为载气被导入到化学气相沉积反应腔中，沉积形成 50-100nm的绝缘层，其中，甲基三乙氧基硅垸与柠檬烯的流量比 =1： 1〜1 :2.5，该流量以克 /分钟计； Step 1. Depositing a thin film by plasma enhanced chemical vapor deposition: using methyltriethoxysilane and limonene as reaction sources, and methyltriethoxysilane and limonene are introduced into the carrier gas by using helium as a carrier gas. In the chemical vapor deposition reaction chamber, a 50-100 nm insulating layer is deposited, wherein a flow ratio of methyltriethoxysilane to limonene is 1:1 to 1:2.5, and the flow rate is in grams per minute;

步骤 2，在上述腔体中采用 Ar或 He等离子体对绝缘层表面进行原位处理 1-5分钟，形成致密的修饰层，此修饰层的作用是阻止水分子在整个绝缘层中由上而下的扩散，从而降低了上述绝缘层中孔隙对水的吸附，遏制了吸水导致介电常数的上升； Step 2: in-situ treatment of the surface of the insulating layer by Ar or He plasma in the above cavity for 1-5 minutes to form a dense modified layer, the function of the modified layer is to prevent water molecules from being in the entire insulating layer. The lower diffusion, thereby reducing the adsorption of water by the pores in the above insulating layer, and suppressing the increase of the dielectric constant caused by water absorption;

步骤 3，重复上述步骤 1和 2，直到达到绝缘薄膜的目标厚度，得到绝缘步骤 4，在惰性气氛中，对步骤 3得到的绝缘薄膜进行高温退火，去除其中的碳氢基团（该碳氢基团包括前躯体中的碳氢基团以及柠檬烯中的碳氢基团），从而形成一种具有多孔结构的超低介电常数绝缘薄膜。 Step 3, repeat steps 1 and 2 above until the target thickness of the insulating film is reached, and insulation is obtained. Step 4, in an inert atmosphere, the insulating film obtained in the step 3 is subjected to high temperature annealing to remove a hydrocarbon group (the hydrocarbon group includes a hydrocarbon group in the precursor and a hydrocarbon group in the limonene) Thereby, an ultra-low dielectric constant insulating film having a porous structure is formed.

上述的方法，其中，步骤 1中的沉积工艺所使用的射频频率为 13.56MHz, 反应腔体中初始真空为 0.018-0.02 托，沉积绝缘层时的衬底温度为 100-400 °C , 功率为 200-600瓦，工作压强为 2-5托 ( 1托 = 133.322Pa), 导入反应腔中 MTES流量为 1.0-2.0克 /分钟， LIMO流量为 1.0-3.5克 /分钟， He 载气流量为 500 - 5000sccm。 The above method, wherein the radio frequency used in the deposition process in step 1 is 13.56 MHz, the initial vacuum in the reaction chamber is 0.018-0.02 Torr, and the substrate temperature at the time of depositing the insulating layer is 100-400 ° C, and the power is 200-600 watts, working pressure 2-5 Torr (1 Torr = 133.322 Pa), MTES flow rate into the reaction chamber is 1.0-2.0 g/min, LIMO flow is 1.0-3.5 g/min, He carrier gas flow is 500 - 5000sccm.

上述的方法，其中，在步骤 2中， Ar或 He等离子体表面处理时功率为 300-600瓦，处理时间为 1-5分钟，气压为 2-8托。 In the above method, in the step 2, the Ar or He plasma surface treatment has a power of 300-600 watts, a treatment time of 1-5 minutes, and a gas pressure of 2-8 Torr.

上述的方法，其中，在步骤 4中，退火温度为 200-420°C，退火炉中的压强为 0.2-0.3托，退火时间为 2-6小时，退火气氛为氩气或者氮气。优选地，上述的退火工艺中， 5-30分钟内由室温上升到所述退火温度。 In the above method, in the step 4, the annealing temperature is 200-420 ° C, the pressure in the annealing furnace is 0.2-0.3 Torr, the annealing time is 2-6 hours, and the annealing atmosphere is argon or nitrogen. Preferably, in the above annealing process, the room temperature rises to the annealing temperature within 5-30 minutes.

上述的方法，其中，所述甲基三乙氧基硅垸和柠檬烯在导入反应腔体之前的汽化温度分别为 50 - 60°C和 60 -100 °C。 The above method, wherein the vaporization temperatures of the methyltriethoxysilane and limonene before introduction into the reaction chamber are 50 - 60 ° C and 60 - 100 ° C, respectively.

本发明还提供了一种采用上述的方法制备的超低介电常数绝缘薄膜，其中，该绝缘薄膜包含：若干层绝缘层；该每层绝缘层上均设置有修饰层，在绝缘层内部具有若干孔隙；该超低介电常数绝缘薄膜介电常数为 2.2-2.4，在 lMV/cm时的漏电流密度为 l(T⁹-l(T⁸A/cm² _; 杨氏模量为 4.2-17GPa，硬度为 0.5-1.3GPa。 The present invention also provides an ultra-low dielectric constant insulating film prepared by the above method, wherein the insulating film comprises: a plurality of insulating layers; each of the insulating layers is provided with a modifying layer, and has a layer inside the insulating layer a plurality of pores; the dielectric constant of the ultra-low dielectric constant insulating film is 2.2-2.4, and the leakage current density at lMV/cm is 1 (T ⁹ -l (T ⁸ A/cm ² _; Young's modulus is 4.2-) 17GPa, hardness 0.5-1.3GPa.

本发明提供的超低介电常数绝缘薄膜的制备方法是分别以 MTES和 LIMO为反应源，在 He载气的携带下导入反应腔体，采用等离子体增强化学气相沉积技术沉积形成绝缘层，然后采用氩气（Ar)或氦气（He)等离子对前述绝缘层表面进行原位处理，形成致密的修饰层，重复上述过程直至达到要求厚度的薄膜，最后将该薄膜置于高温下退火，以去除碳氢基团，从而形成超低介电常数多孔绝缘薄膜。 The ultra low dielectric constant insulating film provided by the invention is prepared by using MTES and LIMO as reaction sources respectively, and is introduced into the reaction cavity under the carrying of He carrier gas, and is deposited by plasma enhanced chemical vapor deposition to form an insulating layer, and then The surface of the insulating layer is treated in situ by argon (Ar) or helium (He) plasma to form a dense modified layer. The above process is repeated until the film of the desired thickness is reached, and finally the film is annealed at a high temperature to The hydrocarbon group is removed to form an ultra-low dielectric constant porous insulating film.

本发明所提供的薄膜采用具有新颖性的反应源 MTES和 LIMO, 简单易得，使用安全，副产物对环境无污染，制备的薄膜介电常数处于 2.2-2.4范围内，在满足超低介电常数的同时还具有较优异的力学特性。另外，薄膜还拥有优良的绝缘性能，在 lMV/cm的外电场下，漏电流密度可以达到 10_⁹-1(T⁸A/_Cm²。因此，本发明所制备的超低介电常数绝缘薄膜能够充分满足先进集成电路对低介电常数材料的电学性能力学性能以及绝缘性能的要求除此以外，本发明提供的薄膜制备方法创新性地采用交替等离子体增强化学气相沉积，形成的薄膜具有良好的抗吸湿性，力学性能较好，与集成工艺相兼容，不仅工艺简单，沉积速率快，而且成膜质量好。附图的简要说明 The film provided by the invention adopts the novel reaction sources MTES and LIMO, is simple and easy to obtain, is safe to use, and the by-products are not polluted to the environment, and the prepared dielectric constant of the film is in the range of 2.2-2.4, which satisfies the ultra-low dielectric. The constant also has superior mechanical properties. In addition, the film also has excellent insulation properties, and the leakage current density can be reached under an external electric field of lMV/cm. 10_ ⁹ -1(T ⁸ A/ _C m ² . Therefore, the ultra-low dielectric constant insulating film prepared by the invention can fully satisfy the requirements of the advanced integrated circuit for the electrical mechanical properties and the insulation performance of the low dielectric constant material. In addition, the thin film preparation method provided by the invention innovatively adopts alternating plasma enhanced chemical vapor deposition, and the formed film has good moisture absorption resistance, good mechanical properties, and is compatible with the integrated process, and the process is simple, and the deposition rate is fast. And the film quality is good. Brief description of the drawing

图 la-Id为本发明的超低介电常数绝缘薄膜的制备过程示意图。实现本发明的最佳方式 Figure la-Id is a schematic view showing the preparation process of the ultra-low dielectric constant insulating film of the present invention. The best way to implement the invention

下面结合附图与具体实施方式对本发明作进一步详细说明。在图中，为了方便说明，放大或缩小了不同层和区域的尺寸，所示大小并不代表实际尺寸，也不反映尺寸的比例关系。 The present invention will be further described in detail below in conjunction with the drawings and specific embodiments. In the drawings, the dimensions of the different layers and regions are enlarged or reduced for convenience of explanation. The size shown does not represent the actual size, nor does it reflect the proportional relationship of the dimensions.

本发明采用等离子体增强化学气相沉积技术来制备超低介电常数绝缘薄膜，以氦气（He) 为载气，分别将前驱体甲基三乙氧基硅烷（C₇H₁₈0₃ Si，简称 MTES)和成孔剂柠檬烯（C₁₍₎H₁₆, 简称 LIMO)带入等离子体增强化学气相沉积反应腔体中沉积形成绝缘层，等离子体增强化学气相沉积工艺所使用的射频频率为 13.56MHz, 反应腔体中初始真空为 0.018〜0.02托，衬底温度为 100〜400°C，沉积功率为 200~ 600瓦，工作压强为 2~5托， He载气流量为 500〜5000sccm (standard-state cubic centimeter per minute )。 MTES禾口 LIMO在导入反应腔体之前的汽化温度分别为 50〜60°C和 60~100°C， MTES 流量是 1.0-2.0g克 /分钟, LIMO流量是 1.0-3.5克 /分钟,比值为 1 :1-1:2.5，沉积厚度为 50-100nm，形成如图 la所示的绝缘层 10，该绝缘层 10由 Si-O-Si结构 11和碳氢基团 12构成。 The invention adopts plasma enhanced chemical vapor deposition technology to prepare an ultra-low dielectric constant insulating film, and uses helium (He) as a carrier gas to respectively drive the precursor methyltriethoxysilane (C ₇ H ₁₈ 0 ₃ Si, The MTES) and the pore former limonene (C ₁₍₎ H ₁₆ , referred to as LIMO) are introduced into the plasma enhanced chemical vapor deposition reaction chamber to form an insulating layer. The RF frequency used in the plasma enhanced chemical vapor deposition process is 13.56. MHz, the initial vacuum in the reaction chamber is 0.018~0.02 Torr, the substrate temperature is 100~400°C, the deposition power is 200~600 watts, the working pressure is 2~5 Torr, and the He carrier gas flow is 500~5000sccm (standard) -state cubic centimeter per minute ). The vaporization temperatures of MTES and LIMO before introduction into the reaction chamber are 50~60°C and 60~100°C respectively, the MTES flow rate is 1.0-2.0g g/min, and the LIMO flow rate is 1.0-3.5g/min. The ratio is 1 : 1-1: 2.5, a deposition thickness of 50 - 100 nm, forming an insulating layer 10 as shown in FIG. 1a, the insulating layer 10 being composed of a Si-O-Si structure 11 and a hydrocarbon group 12.

在上述腔体中采用 Ar或 He等离子体对绝缘层表面进行原位处理以形成致密的修饰层 20 (如图 lb所示)，功率为 300-600瓦，处理时间为 1-5分钟，气压为 2-8托。该修饰层 20的作用是封住绝缘层 10的外表面，防止绝缘层 10内退火形成的孔隙吸水。 The surface of the insulating layer is treated in situ by Ar or He plasma in the above cavity to form a dense modified layer 20 (as shown in FIG. 1b), with a power of 300-600 watts, a processing time of 1-5 minutes, and a gas pressure. It is 2-8 Torr. The function of the modifying layer 20 is to seal the outer surface of the insulating layer 10 to prevent the pores formed by annealing in the insulating layer 10 from absorbing water.

分别重复上述两个步骤从而达到目标厚度的绝缘薄膜，如图 lc所示，形成了 3次绝缘层-修饰层交替设置的绝缘薄膜 30。将上述目标绝缘薄膜 30置于退火炉中， Ar或者 N₂氛围下，退火炉压强为 0.2-0.3托， 5-30分钟内由室温上升到退火温度， 200-420 °C条件下退火 2-6 小时，去除碳氢基 a在绝缘薄膜的绝缘层内部形成若干不规则的孔隙 13 (该孔隙 13包括若干蠕虫状孔及若干不规则圆孔），最终获得具有多孔结构的超低介电常数绝缘薄膜，如图 Id所示。 The above two steps are respectively repeated to reach the insulating film of the target thickness, and as shown in FIG. 1c, the insulating film 30 in which the insulating layer-decorating layer is alternately disposed is formed three times. The target insulating film 30 is placed in an annealing furnace, and the annealing furnace has a pressure of 0.2-0.3 Torr in Ar or N ₂ atmosphere, and rises from room temperature to annealing temperature in 5-30 minutes, and is annealed at 200-420 ° C. 6 hours, the removal of the hydrocarbon group a forms a plurality of irregular pores 13 inside the insulating layer of the insulating film (the pore 13 includes a plurality of worm-like pores and a plurality of irregular circular holes), and finally obtains an ultra-low dielectric constant having a porous structure. Insulating film, as shown in Figure Id.

薄膜性能测量：为了测量上述薄膜的电学性能，本发明以低阻硅片（电阻率为 0.001-0.02Ω·οπι) 为衬底，以电子束蒸发的铝在薄膜上形成直径为 400-420微米的圆形金属电极以构成电容器，从而得到金属-绝缘体-半导体 (简称 MIS) 电容结构。在室温下上述电容器基于电容 -电压特性来测定电容，并通过多点测试来获得可靠的平均电容值，同时考虑电极的面积和薄膜厚度来确定介电常数。此外，通过对电流-电压的测量获得薄膜的漏电特性。通过纳米压痕仪获得薄膜的硬度和杨氏模量。 Film property measurement: In order to measure the electrical properties of the above film, the present invention uses a low-resistance silicon wafer (resistance of 0.001-0.02 Ω·οπι) as a substrate, and electron beam evaporated aluminum forms a diameter of 400-420 μm on the film. A circular metal electrode is used to form a capacitor, thereby obtaining a metal-insulator-semiconductor (MIS) capacitor structure. The above capacitors are measured based on the capacitance-voltage characteristics at room temperature, and a reliable average capacitance value is obtained by a multi-point test, and the dielectric constant is determined in consideration of the electrode area and the film thickness. In addition, the leakage characteristics of the film are obtained by measuring the current-voltage. The hardness and Young's modulus of the film were obtained by a nanoindenter.

实施例 1-6中，通过改变甲基三乙氧基硅垸和柠檬烯的相对流量，制备出了 7种不同的薄膜样品（即，编号为 1-6的样品），表 2列出了在不同流量比条件下制备出的样品的电学性能，力学性能和漏电流大小。随着相对流量逐渐增大，介电常数及其力学性能都表现出先减小后增大的趋势。由表 2可以看出，所得薄膜的最低介电常数为 2.2，折射率为 1.309，力学性能方面，硬度为 0.55GPa,杨氏模量为 4.23GPa，达到文献报道的多孔低介电常数薄膜力学性能的普遍水平，另外其他样品也表现出了优良的力学性能。同时漏 o电流密度也较小，表现出较好的绝缘性能。因此，可以满足下一代集成电路工艺对低介电常数薄膜材料的要求。 In Examples 1-6, seven different film samples (i.e., samples numbered 1-6) were prepared by varying the relative flow rates of methyltriethoxysilane and limonene. Table 2 lists The electrical properties, mechanical properties and leakage current of the samples prepared under different flow ratio conditions. As the relative flow rate increases, the dielectric constant and its mechanical properties show a trend of decreasing first and then increasing. It can be seen from Table 2 that the obtained film has a minimum dielectric constant of 2.2 and a refractive index of 1.309. In terms of mechanical properties, the hardness is 0.55 GPa and the Young's modulus is 4.23 GPa, which has reached the porous low dielectric constant film mechanics reported in the literature. The general level of performance, and other samples also showed excellent mechanical properties. At the same time, the leakage current density is also small, showing good insulation performance. Therefore, it is possible to meet the requirements of the next-generation integrated circuit process for low dielectric constant thin film materials.

表 2: 样品的沉积速率，电学性能，力学性能和漏电流大小 Table 2: Sample deposition rate, electrical properties, mechanical properties and leakage current

IMV/cm时样品介电常数沉积速率杨氏模硬度 IMV/cm sample dielectric constant deposition rate Young's modulus hardness

相对流量折射率漏电流密度编号 (k) (nm/min) 量 (GPa) (GPa) Relative Flow Refractive Index Leakage Current Density Number (k) (nm/min) Amount (GPa) (GPa)

比 (A/cm²)Ratio (A/cm ² )

1 1： 1 2.4 1.355 37.5 14.51 1.32 7.3X10-⁹ 1 1: 1 2.4 1.355 37.5 14.51 1.32 7.3X10- ⁹

2 1： 1.2 2.4 1.344 35.3 12.4 1.13 8.2X 10-⁹ 2 1: 1.2 2.4 1.344 35.3 12.4 1.13 8.2X 10- ⁹

3 1： 1.4 2.3 1.336 36.5 10.57 0.84 1.5X10-⁸ 3 1: 1.4 2.3 1.336 36.5 10.57 0.84 1.5X10- ⁸

4 1： 1.5 2.2 1.309 33.7 4.23 0.55 5.3 χΐθ"⁹ 4 1: 1.5 2.2 1.309 33.7 4.23 0.55 5.3 χΐθ" ⁹

5 1： 1.7 2.4 1.357 37.7 15.32 0.99 5 1: 1.7 2.4 1.357 37.7 15.32 0.99

6 1： 2.0 2.4 1.356 35.1 17.01 0.95 8.4x10"⁹ 尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的保护范围应由所附的权利要求来限定。 6 1: 2.0 2.4 1.356 35.1 17.01 0.95 8.4x10" ⁹ Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Numerous modifications and substitutions of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be defined by the appended claims.

Claims

权利要求 Rights request

1. 一种超低介电常数绝缘薄膜的制备方法，其特征在于，该方法包含如下具体步骤- 步骤 1，利用等离子体增强化学气相沉积技术沉积薄膜：以甲基三乙氧基硅垸和柠檬烯为反应源，且甲基三乙氧基硅垸和柠檬烯均以氦气为载气被导入到化学气相沉积反应腔中形成绝缘层，厚度为 50-100nm，其中，甲基三乙氧基硅烷与柠檬烯的流量比为 1:1~1:2.5，该流量以克 /分钟计； A method for preparing an ultra-low dielectric constant insulating film, characterized in that the method comprises the following specific steps - step 1, depositing a film by plasma enhanced chemical vapor deposition: using methyltriethoxysilane and Limonene is the reaction source, and methyltriethoxysilane and limonene are introduced into the chemical vapor deposition reaction chamber with helium as a carrier gas to form an insulating layer with a thickness of 50-100 nm, wherein methyltriethoxy group The flow ratio of silane to limonene is 1:1~1:2.5, and the flow rate is in grams per minute;

步骤 2，在上述腔体中采用 Ar或 He等离子体对绝缘层表面进行原位处理以形成致密的修饰层，等离子体处理时间为 1-5分钟； Step 2, in-situ treatment of the surface of the insulating layer by Ar or He plasma in the above cavity to form a dense modified layer, and the plasma treatment time is 1-5 minutes;

步骤 3，重复上述步骤 1和 2，直到达到绝缘薄膜的目标厚度，得到绝缘薄膜； Step 3, repeating the above steps 1 and 2 until the target thickness of the insulating film is reached to obtain an insulating film;

步骤 4，在惰性气氛中，对步骤 3得到的绝缘薄膜进行高温退火，去除其中的碳氢基团，从而形成一种具有多孔结构的超低介电常数绝缘薄膜。 In step 4, the insulating film obtained in the step 3 is subjected to high-temperature annealing in an inert atmosphere to remove the hydrocarbon groups therein, thereby forming an ultra-low dielectric constant insulating film having a porous structure.

2.如权利要求 1所述的方法，其特征在于，步骤 1中的沉积工艺所使用的射频频率为 13.56MHz, 反应腔体中初始真空为 0.018-0.02托，沉积绝缘层时的衬底温度为 100-400°C，功率为 200-600瓦，工作压强为 2-5托，导入反应腔中甲基三乙氧基硅垸流量为 1.0-2.0克 /分钟，柠檬烯流量为 1.0-3.5克 /分钟， He载气流量为 500 - 5000sccm。 2. The method according to claim 1, wherein the RF frequency used in the deposition process in step 1 is 13.56 MHz, the initial vacuum in the reaction chamber is 0.018-0.02 Torr, and the substrate temperature when the insulating layer is deposited. It is 100-400 ° C, the power is 200-600 watts, the working pressure is 2-5 Torr, the flow rate of methyltriethoxysilane in the reaction chamber is 1.0-2.0 g/min, and the flow rate of limonene is 1.0-3.5 g. /min, He carrier gas flow rate is 500 - 5000sccm.

3.如权利要求 1所述的方法，其特征在于，在步骤 2中， Ar或 He等离子体表面处理时功率为 300-600瓦，处理时间为 1-5分钟，气压为 2-8托。 The method according to claim 1, wherein in the step 2, the Ar or He plasma surface treatment has a power of 300-600 watts, a treatment time of 1-5 minutes, and a gas pressure of 2-8 Torr.

4. 如权利要求 1所述的方法，其特征在于，在步骤 4中，退火工艺为：退火温度为 200-420°C，退火炉中的压强为 0.2-0.3托，退火时间为 2-6小时，退火气氛为氩气或者氮气。 4. The method according to claim 1, wherein in the step 4, the annealing process is: annealing temperature is 200-420 ° C, pressure in the annealing furnace is 0.2-0.3 Torr, and annealing time is 2-6 In an hour, the annealing atmosphere is argon or nitrogen.

5. 如权利要求 4所述的方法，其特征在于，上述的退火工艺中， 5-30分钟内由室温上升到所述退火温度 5. The method according to claim 4, wherein in the annealing process, within 5-30 minutes Rising from room temperature to the annealing temperature

6. 如权利要求 1所述的方法，其特征在于，所述甲基三乙氧基硅垸和柠檬烯在导入反应腔体之前的汽化温度分别为 50 - 60Ό和 60 -100°C。 6. The method according to claim 1, wherein the methyltriethoxysilane and limonene have a vaporization temperature of 50 - 60 Torr and 60 - 100 ° C before being introduced into the reaction chamber, respectively.

7.一种采用权利要求 1所述的方法制备的超低介电常数绝缘薄膜，其特征在于，该绝缘薄膜包含：若干层绝缘层（10); 该每层绝缘层（10)上均设置有修饰层（20)，在绝缘层（10) 内部具有若干孔隙（13 ); 该超低介电常数绝缘薄膜介电常数为 2.2-2.4，在 lMV/cm时的漏电流密度为 10'⁹-l(T⁸A/cm² _; 杨氏模量为 4.2-17GPa，硬度为 0.5-1.3GPa。 An ultra-low dielectric constant insulating film prepared by the method of claim 1, wherein the insulating film comprises: a plurality of insulating layers (10); each of the insulating layers (10) is disposed with a modification layer (20) having a plurality of apertures (13) in the insulating layer (10); the ultra low-k dielectric constant insulating film is 2.2 to 2.4, the leakage current density at lMV / cm to 10 ^'9 -l (T ⁸ A/cm ² _; Young's modulus is 4.2-17 GPa, hardness is 0.5-1.3 GPa.