Method for manufacturing zirconium oxide film for use in semiconductor device

[0002] The present invention relates to a semiconductor device and, more particularly, to a method for manufacturing a zirconium oxide film for use in a semiconductor device by using Zr(OC(CH₃)₃)₄(zirconium tetra-tert-butoxide) as a zirconium oxygen source material in place of conventional ZrCl₄.

[0003] Generally, in a semiconductor memory device, various dielectric materials are used for a gate oxide film and a capacitor thin film so that dielectric properties mainly affect derivability of the semiconductor memory device.

[0004] With high integration and high speed of the semiconductor memory device, research has been undertaken for application of a titanium oxide (TiO₂) or an aluminum oxide (Al₂O₃) as the dielectric material in place of a conventional silicon oxide (SiO₂).

[0005] A zirconium oxide (ZrO₂) film has been applied to the gate oxide film of the semiconductor memory devices with high integration. The zirconium oxide is formed by using an atomic film deposition (ALD) technique. Conventionally, ZrCl₄and vaporized water (H₂O) are used as a zirconium source material and an oxygen source material, respectively.

[0006] In more detail, a conventional manufacturing method for forming the zirconium oxide film includes the steps of setting a wafer in a reaction chamber; heating the wafer up to a predetermined temperature; supplying the zirconium source material of ZrCl₄into the reaction chamber; purging out unreacted ZrCl₄; supplying the oxygen source material of vaporized H₂O into the chamber; and purging out unreacted vaporized H₂O. This is one cycle for depositing the zirconium oxide film. By repeating this cycle, the intended thickness of the zirconium oxide film is obtained.

[0007] However, since the conventional method utilizes ZrCl₄as the zirconium source material, the zirconium oxide film of the prior art has a disadvantage in that there are chlorines (Cl) remaining in the zirconium oxide film. As a result, an electrical property of the device is degraded and an agglomeration of the zirconium oxide film is apt to occur. In addition, the ZrCl₄is characteristically in a solid state at room temperature and it is melted at a temperature of 437° C. and a pressure of 25 atm. Therefore, it is difficult to supply the ZrCl₄into the reaction chamber in a gaseous state.

[0008] It is, therefore, an object of the present invention to provide a method for manufacturing a zirconium oxide film by 25 using Zr(OC(CH₃)₃)₄(zirconium tetra-tert-butoxide) as a zirconium source material instead of conventional ZrCl₄, thereby inhibiting the remainder of chlorine in the zirconium oxide film.

[0009] In accordance with one aspect of the present invention, there is provided a method for manufacturing a zirconium oxide film for use in a semiconductor device by using an atomic layer deposition (ALD), the method comprising steps of a) setting a wafer in a reaction chamber; b) supplying a zirconium source material of Zr(OC(CH₃)₃)₄into the reaction chamber; c) purging out unreacted Zr(OC(CH₃)₃)₄; d) supplying an oxygen source material into the reaction chamber; and e) purging out unreacted oxygen source material.

[0010] In accordance with another aspect of the present invention, there is provided a method for manufacturing a zirconium oxide film for use in a semiconductor device by using an atomic layer deposition (ALD), the method comprising steps of a) setting a wafer in a reaction chamber; b) supplying a zirconium source material of Zr(OC(CH₃)₃)₄into the reaction chamber; c) purging out unreacted Zr(OC(CH₃)₃)₄; d) supplying nitrogen species gas into the reaction chamber; and e) purging out unreacted nitrogen species gas.

[0011] The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:

[0012] FIG. 1 is a schematic view of an apparatus for forming a zirconium oxide film in accordance with a preferred embodiment of the present invention.

[0013] Referring to FIG. 1, there is provided a schematic view of an apparatus for forming a zirconium oxide film in accordance with a preferred embodiment of the present invention. The manufacturing steps begin with setting a wafer 12 in a reaction chamber 10 provided with a discharging pump 11. Thereafter, Zr(OC(CH₃)₃)₄(zirconium tetra-tert-butoxide) is supplied as a zirconium source material into the reaction chamber 10 for a period of approximately 0.1 seconds to approximately 3 seconds while the wafer heats up to a temperature ranging from approximately 250° C. to approximately 450° C. and the Zr(OC(CH₃)₃)₄is absorbed on a surface of the wafer 12.

[0014] In a next step, in order to purge out any unreacted Zr(OC(CH₃)₃)₄and a by-product, nitrogen gas (N₂) is supplied into the reaction chamber 10 for a period of approximately 0.1 seconds to approximately 5 seconds. Here, a high vacuum purging process may be carried out instead of the N₂purging process.

[0015] In a subsequent step, an oxygen source material is supplied into the reaction chamber 10 for a period of approximately 0.1 seconds to approximately 5 seconds, whereby the oxygen source material is absorbed on the surface of the wafer 12. It is preferable that the oxygen source material include vaporized water (H₂O), O₂gas, N₂O gas, O₃gas or the like.

[0016] Thereafter, in order to purge out any unreacted oxygen source material and a by-product, nitrogen gas (N₂) is supplied into the reaction chamber 10 for a period of approximately 0.1 seconds to approximately 5 seconds. Here, the high vacuum purging process may also be carried out instead of the N₂purging process.

[0017] This represents one cycle for depositing the zirconium oxide film. By repeating this cycle numerous times, an intended thickness of the zirconium oxide film may be obtained. It is preferable that a pressure in the reaction chamber 10 should be kept within a range of approximately 100 mtorr to approximately 3 Torr. Here, reference numerals 13, 14 denote a vessel for storing the Zr(OC(CH₃)₃)₄and a vessel for storing the oxygen source material, respectively.

[0018] Meanwhile, NH₃gas as an active gas can be supplied into the reaction chamber 10 simultaneously, with a flux rate of 20 standard cubic centimeters per minute (sccm) to 1,000 sccm, when the Zr(OC(CH₃)₃)₄is supplied. At this time, separate supply-pipes should be used. If NH₃gas and the Zr(OC(CH₃)₃)₄are supplied into the reaction chamber 10 through the same supply-pipe, the Zr(OC(CH₃)₃)₄reacts with the NH₃gas, thereby producing particles in the supply-pipe.

[0019] While supplying the oxygen source material, NH₃gas as the active gas also can be supplied into the reaction chamber 10 simultaneously through the same supply-pipe. If NH₃gas is not supplied into the reaction chamber 10 through the same supply-pipe as used for the oxygen source material, lots of particles may be produced.

[0020] NH₃gas may also be supplied simultaneously when the Zr(OC(CH₃)₃)₄and the oxygen source material are supplied into the reaction chamber 10 under the same conditions aforementioned. It is noted that the active gas can be substituted by mixed gas of H₂and N₂instead of NH₃gas.

[0021] Finally, after the deposition reaction, carbon (C), hydrogen (H) particles or other impurities may exist in the zirconium oxide film, thereby degrading a resulting electrical property. Thus, the following process is carried out to avoid deterioration of the electrical property using a method such as O₂plasma, N₂O plasma, UV/O₃or the like.

[0022] Since the Zr(OC(CH₃)₃)₄has oxygen atoms therein, the zirconium oxide film may be formed without using the oxygen source material such as H₂O, O₂, N₂O or O₃. At this time, NH₃or H₂+N₂gas is supplied into the reaction chamber 10 through the supply-pipe of the oxygen source material. That is, the steps include supplying the Zr(OC(CH₃)₃)₄; N₂purging; supplying NH₃gas; N₂purging or vacuum purging. In addition, NH₃gas and the Zr(OC(CH₃)₃)₄can also be supplied into the reaction chamber simultaneously through their respective supply-pipes.

[0023] In comparison with the prior art, the inventive method uses the Zr(OC(CH₃)₃)₄as the zirconium source material. As a result, it is possible to inhibit chlorine residues after deposition, thereby preventing degradation of the electrical property and an agglomeration of the zirconium oxide film. Furthermore, the Zr(OC(CH₃)₃)₄has a boiling point of approximately 900° C. so that it is not difficult to supply the Zr(OC(CH₃)₃)₄into the reaction chamber in a gaseous state. In addition, the active gas used in the inventive method, e.g., NH₃or a mixed gas of H₂and N₂, reacts with the Zr(OC(CH₃),₃)₄, thereby forming a hydrocarbon such as CH₄, CH₃or the like. Thus, this active gas accelerates the decomposition of the zirconium or oxygen source material and reduces the concentration of impurities in the zirconium oxide film.

[0024] Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.