Deposition of High Quality SiO 2 Films Using Teos by ECR Plasma
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and Y.HATANAKA** *Development Division II, Suzuki Motor Corporation, 300 Takatsuka-cho, Hamamatsu-shi **Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu-shi, rdwsun@ rie.shizuoka.ac.jp ABSTRACT SiO2 thin firms were fabricated in a remote electron cyclotron resonance (ECR) plasma by tetraethoxysilane (TEOS) as the silicon source. Oxygen was used as the plasma gas. A mesh was placed between the TEOS gas outlet and the substrate. In the present investigation a-Si02 films were deposited with and without the mesh and film properties were studied comparatively. The deposition rate increased when the mesh was attached. The optimum deposition rate is observed when the mesh voltage was zero, that is the mesh was grounded. The deposition rates of both methods were also dependnt on the TEOS flow rate, applied microwave power and the substrate temperature. These three parameters have significant roles in controlling the film quality. Good quality SiO2 films can be obtained with a higher deposition rate when a mesh is attached. INTRODUCTION Accompanying developments in miniaturization in the increased scale of integration within ULSI technology has required further functional enhancement of Si02 deposition, which is used to provide interlayer dielectric films in multilevel interconnections. Such improvements would include (1) film deposition with a higher growth rate (2) film deposition at lower temperatures and (3) the reduction of H20, -OH, and C content within the film [1-3]. As a response to these various new requirements, several processes are currently being investigated, including enhanced plasma CVD, thermal CVD and ozone CVD process [2-8]. However, it has been extremely difficult to find a process that satisfies all of the requirements for the deposition of dielectric films. For instance, a remote plasma CVD process where TEOS/02 chemistry is used, produces high quality SiO2 films at the substrate temperatures above 400'C. In this process, a lower growth rate of SiO2 films was observed [2][3]. Further, some claim that this process lacks reliability, as the substrates were heated up to higher temperatures for a long time, which causes a destruction of the aluminum wires
of the device [1]. The ECR plasma CVD process is expected to be a better deposition method because it has a higher ionization ratio of the reaction gas, and permits efficient deposition of high
quality film under low temperatures [9-11]. Recently, monosilane (SiH4) is being replaced by TEOS because of its higher safety level and good step coverage characteristic than that of obtained with SiH4 [12]. This paper reports a technique for high speed deposition of Si02 films. The Si02 film deposited by the TEOS/02-remote ECR plasma using a mesh could satisfy all of the requirements noted above. Moreover, films deposited by this method do not include H20, -OH and C, even though the deposition is carried out at low substrate temperatures. The film qualities are also discussed by controlling the TEOS flow rate and applied microwav
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