J. Semicond. > 2016, Volume 37 > Issue 1 > 016002

SEMICONDUCTOR TECHNOLOGY

Investigation of aluminum gate CMP in a novel alkaline solution

Cuiyue Feng, Yuling Liu, Ming Sun, Wenqian Zhang, Jin Zhang and Shuai Wang

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 Corresponding author: Liu Yuling,Email:liuyl@jingling.com.cn

DOI: 10.1088/1674-4926/37/1/016002

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Abstract: Beyond 45 nm, due to the superior CMP performance requirements with the metal gate of aluminum in the advanced CMOS process, a novel alkaline slurry for an aluminum gate CMP with poly-amine alkali slurry is investigated. The aluminum gate CMP under alkaline conditions has two steps:stock polishing and fine polishing. A controllable removal rate, the uniformity of aluminum gate and low corrosion are the key challenges for the alkaline polishing slurry of the aluminum gate CMP. This work utilizes the complexation-soluble function of FA/O Ⅱ and the preference adsorption mechanism of FA/O Ⅰ nonionic surfactant to improve the uniformity of the surface chemistry function with the electrochemical corrosion research, such as OCP-TIME curves, Tafel curves and AC impedance. The result is that the stock polishing slurry (with SiO2 abrasive) contains 1 wt.% H2O2 ,0.5 wt.% FA/O Ⅱ and 1.0 wt.% FA/O Ⅰ nonionic surfactant. For a fine polishing process, 1.5 wt.% H2O2 , 0.4 wt.% FA/O Ⅱ and 2.0 wt.% FA/O Ⅰ nonionic surfactant are added. The polishing experiments show that the removal rates are 3000±50 Å/min and 1600±60 Å/min, respectively. The surface roughnesses are 2.05±0.128 nm and 1.59±0.081 nm, respectively. A combination of the functions of FA/O Ⅱ and FA/O Ⅰ nonionic surfactant obtains a controllable removal rate and a better surface roughness in alkaline solution.

Key words: alkaline solution, aluminum, CMP, electrochemical, surface micromorphology



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Fig. 1.  Potential-pH diagram of aluminum.

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Fig. 2.  Aluminum corrosion rate as the function of H$_{2}$O$_{2}$ and FA/O II concentration.

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Fig. 3.  $E_{\rm oc}$ of aluminum electrode as the function of FA/O II concentration.

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Fig. 4.  (Color online) Tafel plots for aluminum recorded using 1~mV/s voltage scans. (a) 0.15 wt.{\%} H$_{2}$O$_{2}$ and $y$ wt.{\%} FA/O I. (b) 0.3~wt.{\%} H$_{2}$O$_{2}$ and $y$ wt.{\%} FA/O II. (c) 0.45 wt.{\%} H$_{2}$O$_{2}$ and $y$ wt.{\%} FA/O II ($y=$ 0.1, 0.2, 0.3, 0.4, 0.5).

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Fig. 5.  (a) Corrosion potentials and (b) corrosion current of aluminum electrode as functions of FA/O II concentration.

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Fig. 6.  Tafel plots for aluminum recorded using 1 mV/s voltage scans in 1 wt.{\%} H$_{2}$O$_{2}$ ,0.5 wt.{\%} FA/O II and $m$ wt.{\%} FA/O I nonionic surfactant ($m=$ 0.5, 1.0, 1.5).

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Fig. 7.  (a) Contact angle curve for aluminum as a function of FA/O I nonionic surfactant concentration. Contact angle in slurry with 1.0~wt.{\%} H$_{2}$O$_{2}$ , 0.5 wt.{\%} FA/O II and (b) 0 wt.{\%} FA/O I nonionic surfactant (c) 2.0 wt.{\%} FA/O I nonionic surfactant.

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Fig. 8.  (a) AC impedance without FA/O I nonionic and (b) AC impedance with FA/O I nonionic saturation adsorption. (c) Surfactant surface coverage $\theta$ as the function of FA/O I nonionic surfactant.

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Fig. 9.  (Color online) Surface morphology of aluminum. (a) Before polishing. (b) After stock polishing in slurry with 0.3 wt.{\%} H$_{2}$O$_{2}$, 0.5~wt.{\%} FA/O II and 1.0 wt.{\%} FA/O I nonionic surfactant. (c) After fine polishing in slurry with 0.45 wt.{\%} H$_{2}$O$_{2}$ ,0.4 wt.{\%} FA/O II and 2.0~wt.{\%} FA/O I nonionic surfactant.

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Table 1.   $E_{\rm corr}$ and $I_{\rm corr}$ of aluminum electrode as functions of FA/O I nonionic surfactant.

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    Received: 07 April 2015 Revised: Online: Published: 01 January 2016

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      Article Navigation >  Journal of Semiconductors  > 2016  >  37(1): 016002
      Cuiyue Feng, Yuling Liu, Ming Sun, Wenqian Zhang, Jin Zhang, Shuai Wang. Investigation of aluminum gate CMP in a novel alkaline solution[J]. Journal of Semiconductors, 2016, 37(1): 016002. doi: 10.1088/1674-4926/37/1/016002 ****C Y Feng, Y L Liu, M Sun, W Q Zhang, J Zhang, S Wang. Investigation of aluminum gate CMP in a novel alkaline solution[J]. J. Semicond., 2016, 37(1): 016002. doi: 10.1088/1674-4926/37/1/016002.
      Citation:
      Cuiyue Feng, Yuling Liu, Ming Sun, Wenqian Zhang, Jin Zhang, Shuai Wang. Investigation of aluminum gate CMP in a novel alkaline solution[J]. Journal of Semiconductors, 2016, 37(1): 016002. doi: 10.1088/1674-4926/37/1/016002 ****
      C Y Feng, Y L Liu, M Sun, W Q Zhang, J Zhang, S Wang. Investigation of aluminum gate CMP in a novel alkaline solution[J]. J. Semicond., 2016, 37(1): 016002. doi: 10.1088/1674-4926/37/1/016002.
      shu

      Investigation of aluminum gate CMP in a novel alkaline solution

      DOI: 10.1088/1674-4926/37/1/016002

      • Institute of Microelectronics, Hebei University of Technology, Tianjin 300130, China

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      • Corresponding author: Liu Yuling,Email:liuyl@jingling.com.cn
      • Received Date: 2015-04-07
      • Accepted Date: 2015-06-03
      • Published Date: 2016-01-25

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