24September2017

Materials and Electronics Engineering

Preparation of carbon nanowalls and the application in chip cooling

Yan Zhang1,*, Chuyun He1, Shiwei Ma1, Haomin Wang1, Johan Liu1,3

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1SMIT Center, School of Mechatronics Engineering and Automation & Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai, China
2State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China
3Bionano Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden

Materials and Electronics Engineering 2014,1:8

Publication Date (Web): December 19, 2014 (Article)

DOI:10.11605/mee-1-8

*Corresponding author. E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Abstract

 


Figure 8 (a) IR image of the chip without CNW; (b) the temperature distribution along the centerline of the chip without CNW; (c) IR image of the chip with CNW; (b) the temperature distribution along the centerline of the chip with CNW.

      Carbon nanomaterials, such as fullerenes, carbon nanotube or nanofiber, graphene and so on, have been the frontier of innovation of science and technology in the past decades. Applications of the advance nanomaterials in electronics have also been investigated. In the present paper, the preparation of carbon nanowall (CNW) has been carried out by a plasma enhanced chemical vapor deposition (PECVD) method. The characterization of the CNW samples has been carried out by scanning electron microscope (SEM) and Raman spectra. Then the carbon nanowalls have been applied on a thermal test chip to evaluate its thermal properties. The infrared (IR) thermal imaging is adopted to record the surface temperature of the chip. The thermal performance of carbon nanowall in chip cooling effect is evaluated. And the comparison of the temperature distributions of test chips with and without carbon nanowalls shows quite promising results.


 

Keywords

Carbon nanowall, PECVD, thermal performance, chip cooling

 

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Introduction

        Carbon nanomaterials, such as zero-dimensional fullerenes, one-dimensional carbon nanotubes (CNT), and two-dimensional graphene have attracted great interests in because of their superior to the conventional bulk materials. For example, CNTs discovered in 1991 [1] have been studied on the conductive capabilities [2, 3], and showed promising performance in Mechanics, magnetics, optics and hydrogen storage and other applications [4-6]. The production of the graphene in lab [7, 8] was regarded as the groundbreaking experiments regarding the two-dimensional material. And there were researches about the graphene synthesis methods and potential applications [9-12]

        In the present paper, study on the two-dimensional carbon nanowalls (CNWs) was carried out. The carbon nanowalls were fabricated and characterized, and then applied on a thermal test chip to evaluate its ability of heat dissipation.

Fabrication and characterization of CNWs

2.1 Experimental setup

        A plasma enhanced chemical vapor deposition (PECVD) system was designed and set up to prepare CNWs. As shown in Figure 1, the system include mainly four part, namely the growth area consisting of a high temperature furnace (GL-1100X) and a quartz tube, the vacuum control system, the gas system made up of the gas box and flowmeters, and the plasma generation system including the voltage regulator (TDGC2-1) and the plasma power supply (CTP-2000K).

Figure 1 Schematic diagram of the experimental equipment

Figure 1 Schematic diagram of the experimental equipment

      The hydrogen and methane are used as source gases in the experiment. The gas flow rates of H4 and CH4 are controlled during the fabrication process. The schematic of fabrication process is shown in Figure 2. The process included three stages: the heating-up stage (0-t1) in which the temperature of the substrate in the chamber rises from room temperature RT to the preset temperature T1, the preprocess stage (t1-t2), the CNW growth stage (t2-t3), and the cooling-down stage (t3-t4). Factors such as the gas flow rate (H2:CH4), plasma power, fabrication duration of carbon nanowall at preset temperature are taken into consideration.

Figure 2 The procedure schematic of CNW fabrication

Figure 2 The procedure schematic of CNW fabrication

2.2 Preparation and characterization of carbon nanowalls

        The morphology and microstructure of carbon nanowall samples were observed by a scanning electron microscopy (SEM, ZEISS Supra 55). The SEM images and Raman spectrum of some samples are shown in Figure 3 and 4, and the corresponding process parameters are listed in Table 1. 

Figure 3 SEM images and Raman spectra of CNW samples

Figure 3 SEM images and Raman spectra of CNW samples

        It can be seen from the SEM images that the CNWs distribute uniformly over the metal sheet, and the nanowalls stand perpendicularly on the substrate surface. There are three peaks in the Raman spectra at 1345cm-1, 1583cm-1 and 2700 cm-1, respectively. The carbon nanowall is sp2 hybridization. The narrow FWHM (full width of half maximum) of the characteristic peaks indicate a good quality of the fabricated carbon nanowalls.

        The peak intensity ratio ID/IG of the nanowall depends on the crystallite size. Previous studies also showed a link between the peak intensity ratio ID/IG and the size of the nanowall [13, 14]. Comparing the CNW length L obtained from the SEM images in Figure 3-4 and the peak intensity ratio ID/IG in the Raman spectrum, as listed in Table 1, the nanowalls length has an inverse relationship with ID/IG. With the increase of ID/IG, the appearance of the sample changes from a floc-like structure to clearly vertical nanosheets that form self-supported network structures.

Figure 4 SEM images and Raman spectra of CNW samples

Figure 4 SEM images and Raman spectra of CNW samples

Tab. 1 Parameters of CNW samples 

        During the experimental preparation, it was observed that the carbon nanowall growth began with a thin layer graphite layer parallel to the substrate, and then the nanosheets developed perpendicular to the substrate and the nanowall came into being. Temperature is a key factor in the carbon nanowall fabrication, and has great influence on the morphological properties. Figure 5 is SEM images of CNWs fabricated at different temperatures, where figure (d), (f), (h) are SEM images of the carbon nanowall cross-setion corresponding to those in figure (c), (e) and (g). When the fabrication temperature is lower than 700oC, The naonowall samples show vertically-aligned sheet structures that looks like the top view of flowers, as shown in figure (a) and (b). When the temperature reaches 700 oC, the vertical sheets exhibit open boundary structures from which smaller pieces expanding outward, as indicated in figure (c) and (d). With the increase of temperature, the obtained nanowall samples take on a porous appearance with much smaller-sized vertical walls. So the temperature 700-750oC is a critical one when the significant change occurred in the nanaowall morphological characteristics.

Figure 5 SEM images of CNW sample prepared at (a) 575 oC; (b) 650 oC; (c) 700oC; (d) 700 oC; (e) 750oC; (f) 750oC; (g) 800oC; (h) 800oC

Figure 5 SEM images of CNW sample prepared at (a) 575 oC; (b) 650 oC; (c) 700oC; (d) 700 oC; (e) 750oC; (f) 750oC; (g) 800oC; (h) 800oC

Application of CNWs in the heat dissipation

        After the nanowalls preparation, the samples were applied in the heat dissipation of a power chip to test its validity in thermal management. A test chip was designed for the experiment.

        RTD (resistance temperature detector), also called thermometer, correlates the resistance of the RTD element with its temperature as the material has a predictable linear positive change in resistance when the temperature changes, and therefore can be used to determine the temperature of devices equipped with RTD. As the element can be fabricated in the object, it possesses the ability of in situ temperature monitoring. RTD sensing elements can be made of platinum, copper or nickel, in which platinum is the best because of its wide temperature range, accuracy, and stability. In the present experiment, platinum was chosen to construct a RTD element on a silicon chip. The structure and materials of the test chip designed for the thermal measurement is shown in Figure 6. 

Figure 6 sketch of the test chip structure

Figure 6 sketch of the test chip structure

        This RTD element worked as both a temperature sensor and a hotspot on the test chip during power loadings. Figure 7 shows the top view of the circuit on the test chip, where figure (a) gives the sketch of the circuit on the chip and figure (b) is the photograph of the prepared test chip.

Figure 7 (a) the sketch map of the circuit on the test chip; (b) the photograph of the test chip.

Figure 7 (a) the sketch map of the circuit on the test chip; (b) the photograph of the test chip.

        Concerning the thermal measurement method, Infrared (IR) thermography is a non-contact and real time method with high resolution, high sensitivity. The surface temperature over a large area of the target can be shown as a visual picture [15]. An infrared thermography with a microscopic set was used to measure the temperature distribution of a micro-hotplate array [16]. The infrared imaging technology was applied to acquire micro-temperature distribution of micro-electronic-mechanical devices for failure analysis [17, 18]. Temperature distribution of the chip samples were measured with an infrared thermal image system. A FLIR SC600 infrared camera was adopted to achieve a real-time thermal image record and analysis. A self-designed holder was fabrication to connect the chip with an Agilent E3633A DC power.

        Figure 8 is the thermal measurement results with a power loading of 645W/cm2, where figure (a) and (b) are the bare chip without carbon nanowall applied and figure (c) and (d) are the chip with carbon nanowall transferred on its front surface. Figure (a) and (c) are the IR images of the temperature field on the chip surface, while figure (b) and (d) are the temperature distribution along the centerline. It shows that the hotspot temperature of the chip with CNW is lower than that of the bare chip without CNW, and the temperature distribution along the centerline of the chip with CNW exhibits a more uniform curve with smaller temperature gradient near the hotspot. These indicate that the introduction of the carbon nanowalls can improve the heat dissipation of the chip.

Figure 8 (a) IR image of the chip without CNW; (b) the temperature distribution along the centerline of the chip without CNW; (c) IR image of the chip with CNW; (b) the temperature distribution along the centerline of the chip with CNW.

Figure 8 (a) IR image of the chip without CNW; (b) the temperature distribution along the centerline of the chip without CNW; (c) IR image of the chip with CNW; (b) the temperature distribution along the centerline of the chip with CNW.

        More power loading conditions are studied for the test chip, where the results are shown in Fig. 9. Comparison of hotspot temperature of the chip with and without carbon nanowalls applied under series power loadings shows that the CNW improvement is more obvious when the heat density is higher.

Figure 9 Comparison of hotspot temperature under series power loadings

Figure 9 Comparison of hotspot temperature under series power loadings

Conclusion

        Carbon nanowalls, as a two-dimensional carbon nanomaterial, have been investigated. Different process parameters were studied during the fabrication of carbon nanowalls. The size/length of the nanowall shows an inverse depensend on the peak intensity ratio ID/IG. And the temperature 700-750oC is a critical one for nanowall morphology. When applied on a high-powered chip, the carbon nanowalls have an effect on the heat dissipation of the chip at both improving the temperature distribution and decreasing the hotspot temperature.

References

1. I. Sumio, Helical microtubules of graphitic carbon. Nature 354, 56 (1991). doi:10.1038/354056a0
2. T.W. Odom, J.L. Huang, P. Kim, et al., Atomic structure and electronic properties of single-walled carbon nanotubes. Nature 391, 62 (1998). doi:10.1038/34145
3. S. Berber, Y.K. Kwon, D. Tomanek, Unusually high thermal conductivity of carbon nanotubes. Phys. Rev. Lett. 84, 4613 (2000). doi:10.1103/PhysRevLett.84.4613
4. J. Qiao, X.L. Hu, P. Guan, Y.M. Wang, Research progress of hydrogen storage in carbon nanotubes. Chem. Industry Eng. Prog. 25, 250 (2006).
5. M.J. Biercuk, M.C. Llaguno, M. Radosavljevic, J.K. Hyun, A.T. Johnson, J.E. Fischer, Carbon nanotube composites for thermal management. Appl. Phys. Lett. 80, 2767 (2002). doi:10.1063/1.1469696
6. H.Y. Lin, H. Zhu, H.F. Guo, et al., Investigation of the microwave-absorbing properties of Fe-filled carbon nanotubes. Mater. Lett. 61, 3547 (2007). doi:10.1016/j.matlet.2007.01.077
7. K.S. Novoselov, A.K. Geim, S.V. Morozov, et al., Electric field effect in atomically thin carbon films. Science 306, 666 (2004). doi:10.1126/science.1102896
8. A.K. Geim, K.S. Novoselov, The rise of graphene. Nat. Mater. 6, 183 (2007). doi:10.1038/nmat1849
9. M.J. Allen, V.C. Tung, R.B. Kaner, Honeycomb carbon: a review of graphene. Chem. Rev. 110, 132 (2010). doi:10.1021/cr900070d
10. J. Wu, W. Pisula, K. Mullen, Graphenes as potential material for electronics. Chem. Rev. 107, 718 (2007). doi:10.1021/cr068010r
11. D.C. Wei, Y.Q. Liu, Graphene synthesis: controllable synthesis of graphene and its applications. Adv. Mater. 22, 3225 (2010). doi:10.1002/adma.201090099
12. Z.Y. Wang, N. Li, Z.J. Shi, Z.N. Gu, Low-cost and large-scale synthesis of graphene nanosheets by arc discharge in air. Nanotechnology 21, 175602 (2010).
13. S. Vizireanu, L. Nistor, M. Haupt, V. Katzenmaier, C. Oehr, G. Dinescu, Carbon nanowalls growth by radiofrequency plasma-beam-enhanced chemical vapor deposition. Plasma Process. Polym. 5, 263 (2008). doi:10.1002/ppap.200700120
14. S. Kurita, A. Yoshimura, H. Kawamoto, T. Uchida, K. Kojima, M. Tachibana, P. Molina-Morales, H. Nakai, Raman spectra of carbon nanowalls grown by plasma-enhanced chemical vapor deposition. J. Appl. Phys. 97, 104320 (2005). doi:10.1063/1.1900297
15. X.G. Sun, Y.H. Li, Laser & Infrared 38, 101 (2008).
16. R.H. Zhang, Y.Q. Gu, D.Z. Zhu, J.Y. Hao, Z.N. Tang, Thermal measurement and analysis of micro hotplate array using thermography. Sensor. Actuat. A-Phys. 100, 144 (2002). doi:10.1016/S0924-4247(02)00061-4
17. D.H. Alsem, E.A. Stach, M.T. Dugger, An electron microscopy study of wear in polysilicon microelectromechanical systems in ambient air. Thin Solid Films 515, 3259 (2007). doi:10.1016/j.tsf.2006.01.038
18. J.H. Wang, L. Gao, W. Jin, X.D. He, Detection probability evaluation model based on texture feature of thermal infrared. Infrared and Laser Engineering. 38, 151 (2009).

Acknowledgements

        This work was supported by National Natural Science Foundation of China (11272192), Shanghai Municipal Education Commission Foundation (12ZZ083), Shanghai Natural Science Foundation (12ZR1411400) and Shanghai Science and Technology Grants (12JC1403900).

References

1. I. Sumio, Helical microtubules of graphitic carbon. Nature 354, 56 (1991). doi:10.1038/354056a0 
2. T.W. Odom, J.L. Huang, P. Kim, et al., Atomic structure and electronic properties of single-walled carbon nanotubes. Nature 391, 62 (1998). doi:10.1038/34145 
3. S. Berber, Y.K. Kwon, D. Tomanek, Unusually high thermal conductivity of carbon nanotubes. Phys. Rev. Lett. 84, 4613 (2000). doi:10.1103/PhysRevLett.84.4613 
4. J. Qiao, X.L. Hu, P. Guan, Y.M. Wang, Research progress of hydrogen storage in carbon nanotubes. Chem. Industry Eng. Prog. 25, 250 (2006). 
5. M.J. Biercuk, M.C. Llaguno, M. Radosavljevic, J.K. Hyun, A.T. Johnson, J.E. Fischer, Carbon nanotube composites for thermal management. Appl. Phys. Lett. 80, 2767 (2002). doi:10.1063/1.1469696 
6. H.Y. Lin, H. Zhu, H.F. Guo, et al., Investigation of the microwave-absorbing properties of Fe-filled carbon nanotubes. Mater. Lett. 61, 3547 (2007). doi:10.1016/j.matlet.2007.01.077
7. K.S. Novoselov, A.K. Geim, S.V. Morozov, et al., Electric field effect in atomically thin carbon films. Science 306, 666 (2004). doi:10.1126/science.1102896 
8. A.K. Geim, K.S. Novoselov, The rise of graphene. Nat. Mater. 6, 183 (2007). doi:10.1038/nmat1849 
9. M.J. Allen, V.C. Tung, R.B. Kaner, Honeycomb carbon: a review of graphene. Chem. Rev. 110, 132 (2010). doi:10.1021/cr900070d 
10. J. Wu, W. Pisula, K. Mullen, Graphenes as potential material for electronics. Chem. Rev. 107, 718 (2007). doi:10.1021/cr068010r 
11. D.C. Wei, Y.Q. Liu, Graphene synthesis: controllable synthesis of graphene and its applications. Adv. Mater. 22, 3225 (2010). doi:10.1002/adma.201090099 
12. Z.Y. Wang, N. Li, Z.J. Shi, Z.N. Gu, Low-cost and large-scale synthesis of graphene nanosheets by arc discharge in air. Nanotechnology 21, 175602 (2010).
13. S. Vizireanu, L. Nistor, M. Haupt, V. Katzenmaier, C. Oehr, G. Dinescu, Carbon nanowalls growth by radiofrequency plasma-beam-enhanced chemical vapor deposition. Plasma Process. Polym. 5, 263 (2008). doi:10.1002/ppap.200700120 
14. S. Kurita, A. Yoshimura, H. Kawamoto, T. Uchida, K. Kojima, M. Tachibana, P. Molina-Morales, H. Nakai, Raman spectra of carbon nanowalls grown by plasma-enhanced chemical vapor deposition. J. Appl. Phys. 97, 104320 (2005). doi:10.1063/1.1900297 
15. X.G. Sun, Y.H. Li, Laser & Infrared 38, 101 (2008). 
16. R.H. Zhang, Y.Q. Gu, D.Z. Zhu, J.Y. Hao, Z.N. Tang, Thermal measurement and analysis of micro hotplate array using thermography. Sensor. Actuat. A-Phys. 100, 144 (2002). doi:10.1016/S0924-4247(02)00061-4
17. D.H. Alsem, E.A. Stach, M.T. Dugger, An electron microscopy study of wear in polysilicon microelectromechanical systems in ambient air. Thin Solid Films 515, 3259 (2007). doi:10.1016/j.tsf.2006.01.038 
18. J.H. Wang, L. Gao, W. Jin, X.D. He, Detection probability evaluation model based on texture feature of thermal infrared. Infrared and Laser Engineering. 38, 151 (2009).

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Additional Info

  • Type of Publishing: JOUR - Journal
  • Title:

    Preparation of carbon nanowalls and the application in chip cooling

  • Author: Yan Zhang, Chuyun He, Shiwei Ma, Haomin Wang, Johan Liu
  • Year: 2014
  • Volume: 1
  • Issue: 1
  • Journal Name: Materials and Electronics Engineering
  • Publisher: Nicety Press Company Limited
  • ISSN: 2410-1648
  • URL: http://www.meej.org/volume-1/december-2014/item/369-preparation-of-carbon-nanowalls-and-the-application-in-chip-cooling
  • Abstract:

    Carbon nanomaterials, such as fullerenes, carbon nanotube or nanofiber, graphene and so on, have been the frontier of innovation of science and technology in the past decades. Applications of the advance nanomaterials in electronics have also been investigated. In the present paper, the preparation of carbon nanowall (CNW) has been carried out by a plasma enhanced chemical vapor deposition (PECVD) method. The characterization of the CNW samples has been carried out by scanning electron microscope (SEM) and Raman spectra. Then the carbon nanowalls have been applied on a thermal test chip to evaluate its thermal properties. The infrared (IR) thermal imaging is adopted to record the surface temperature of the chip. The thermal performance of carbon nanowall in chip cooling effect is evaluated. And the comparison of the temperature distributions of test chips with and without carbon nanowalls shows quite promising results.

  • Publish Date: Friday, 19 December 2014
  • Start Page: 8
  • DOI: 10.11605/mee-1-8