JP4489541B2 - Method for cleaning hafnium-containing oxides - Google Patents

Description

  The present invention removes these unnecessary oxides deposited inside reactors such as inner walls and jigs in an apparatus for forming hafnium oxides such as hafnium oxide, silicon hafnium oxide, and aluminum hafnium oxide useful in the semiconductor field. The present invention relates to a cleaning method.

Hf compounds are widely used as wiring materials for semiconductors and the like. In the case of depositing these films, MOCVD or sputtering using Hf (N (CH ₃ ) ₂ ) ₄ or Hf (C ₁₁ H ₁₉ O ₂ ) ₄ as a raw material is performed. However, when film synthesis is performed by these methods, unnecessary Hf-based compounds are deposited on the reactor walls and jigs for holding the substrate. If the accumulation amount of these unnecessary substances increases, it will cause generation of particles and abnormal reactions, so these must be removed as needed. At present, in order to remove these unnecessary deposits, physical cleaning that disassembles the equipment and mechanically removes the unnecessary deposits that have adhered is performed, and wet cleaning that is performed by immersion in acid or alkaline chemicals is performed. Yes. However, in these methods, since the apparatus is once released into the atmosphere, there are problems that dust enters the apparatus and is contaminated, and that the dismantling work itself requires time and labor. Further, when it is directly reacted with hexafluoroacetylacetone (C ₅ H ₂ F ₆ O ₂ ) (hereinafter abbreviated as HFAcAc), the temperature dependence of the cleaning speed is too high, so that the device material has sufficient corrosion resistance against HFAcAc. There was a problem that cleaning was not possible at a temperature of 400 ° C. or lower. Furthermore, cleaning cannot be performed with existing fluorine-based cleaning gases such as ClF ₃ and NF _3, and chlorine-based cleaning gases such as hydrogen chloride and chlorine.

It is stated that cleaning using HFAcAc is effective for barium oxide, strontium oxide, bismuth, tantalum, lead, zirconium and the like at a pressure of 200 Pa or less (Patent Document 1). However, the effect of HFAcAc is extremely low on the Hf oxide targeted by the present invention and cannot be used as a cleaning agent. Japanese Patent Application Laid-Open No. 2004-39976 (Patent Document 2) discloses that HFAcAc has a pressure of 1.33 × 10 ³ Pa to 1.33 × 10 ⁴ Pa, a temperature of 300 ° C. to 450 ° C., Al, Zr , Hf, La, Y, Pr, and Ce, it is shown that a high dielectric material containing at least one of them can be cleaned with HFAcAc containing water or alcohol. However, HFAcAc is not preferable because it forms a solid hydrate with water and adheres to the piping. In addition, this method is practical because only a speed increase of 1.5 to 2.5 times is obtained with respect to HfO ₂ as compared with the case of HFAcAc alone, and the speed is only several tens A / min level. is not. Although the technical field is different from that of apparatus cleaning, addition of water or alcohol has been proposed for etching the substrate surface. However, the effect of accelerating the etching rate is not remarkable (Patent Document 3). Further, the use of HFAcAc is also described in JP-A-6-101076, JP-A-6-228592 (Patent Documents 4 and 5), etc., but the hafnium-containing oxide intended by the invention is used as a CVD apparatus. No cleaning method has been known for removal from the process.
JP 2004-96241 A JP 2004-39976 A JP 2004-91829 A JP-A-6-101076 JP-A-6-228592

  As a result of intensive studies, the inventors of the present invention, in an apparatus for forming a hafnium oxide film, in order to remove these unnecessary compounds deposited inside the reactor such as the inner wall and jig, HFAcAc, hydrogen halide, Alternatively, the inventors have found that the cleaning performance is greatly improved by using a gas mixed with halogen, and have reached the present invention.

That is, according to the present invention, when removing unnecessary hafnium-containing oxide deposited inside a reactor in a semiconductor manufacturing apparatus for forming a hafnium oxide film, HFAcAc and HF, HCl, HBr, HI, F ₂ , Cl _{2 are used.} , Br ₂ , I ₂ , or ClF ₃ , in which the hafnium-containing oxide is a hafnium silicate (Hf _1-x Si _x O _y , Hf _{1). -x Si x O y n z)} , hafnium aluminate _{(Hf 1-x Al x O} m, Hf 1-x Al x O m n n) ( provided that, x, y, z, m , n, 0 < x <1, 0 <y ≦ 2, 0 <z ≦ 1.33, 0 <m ≦ 1.5, 0 <n ≦ 1), and the pressure during cleaning is 20.0 to 101. In the range of 3 kPa The present invention provides a method for cleaning a hafnium-containing oxide.

In the present invention, and HFAcAc, hydrogen halide gas such as HF, halogen gas such as _{F 2,} mixed gas of ClF ₃ is, _{N 2} Ya vapor obtained by heating the vessel containing HFAcAc, or HFAcAc A vapor obtained by blowing an inert gas such as Ar and a gas such as hydrogen halide or F ₂ may be mixed and supplied.

The pressure during cleaning is preferably in the range of 20.0 to 101.3 kPa, more preferably in the range of 34.7 to 53.3 kPa. If it is less than 20.0 kPa, an effective cleaning speed cannot be obtained, and if it exceeds 101.3 kPa, there is a concern about leakage from the reactor, and the cleaning speed does not increase.
Next, the cleaning temperature is preferably in the temperature range of 100 to 500 ° C, more preferably in the temperature range of 150 to 400 ° C. If the temperature is lower than 100 ° C., the effect of increasing the cleaning speed is not remarkable, and if it is 500 ° C. or higher, the apparatus material is damaged, which is not preferable.

  The composition of the cleaning gas may be such that HFAcAc and HF are 10% or more, and more preferably, HF is mixed by 2/3 or more, that is, 6% or more with respect to the concentration of HFAcAc. The flow rate of the cleaning gas is not particularly limited. Even if the flow rate is gradually increased from 400 SCCM or more, the increase in speed becomes moderate.

  The method of the present invention makes it possible to easily clean hafnium-containing oxides that have been difficult to clean.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by this Example.

Examples 1-25, Comparative Examples 1-7
A silicon wafer in which hafnium silicate (Hf _0.6 Si _0.4 O _1.2 ) is formed in a thickness of 400 mm is placed in a quartz glass tube, and an N ₂ diluted gas of HFAcAc, a mixed gas of HFAcAc and HF, or HFAcAc The cleaning rate was measured using a gas obtained by diluting a mixed gas of HF and HF with N ₂ . The results are shown in Table 1. By mixing HFAcAc and HF, the cleaning speed was greatly improved.

Examples 26-29
A silicon wafer in which hafnium silicate (Hf _0.6 Si _0.4 O _1.7 ) is formed in a thickness of 400 mm is placed in a quartz glass tube, and a mixed gas of HFAcAc and HCl is diluted with N _2. The cleaning speed was measured. The results are shown in Table 2. As in the case of HF, a significant increase in the cleaning speed was obtained. The _{Hf 0.6 Si 0.4 O 1.2 N 0.2} ( Example ₂₇₎ instead of the _{Hf 0.6 Si 0.4 O 1.7, Hf} 0.3 Al 0.7 O 0.9 When the same test was performed on (Example 28) and Hf _0.3 Al _0.7 O _0.8 N _0.3 (Example 29), almost the same result (78 A / min) was obtained.

Examples 30, 31
When the cleaning rate of Hf _0.4 Si _0.6 O _1.7 was measured by mixing F ₂ with HFAcAc, the concentration of 230 ° C., 20 kPa, HFAcAc 30%, F ₂ 1%, N ₂ 69%, total Under the condition of a flow rate of 470 SCCM, a cleaning speed of 67 A / min was obtained, the total pressure was increased to 101.3 kPa, and cleaning was performed under the same conditions except that a speed of 115 A / min was obtained. The same result was obtained even when F ₂ was changed to ClF ₃ .

Claims (1)

In removing an unnecessary hafnium-containing oxide deposited inside a reactor in a semiconductor manufacturing apparatus for forming a hafnium oxide film, hexafluoroacetylacetone and HF, HCl, HBr, HI, F ₂ , Cl ₂ , Br _{2 are used.} , I ₂ , or ClF ₃ , a hafnium-containing oxide cleaning method wherein the hafnium-containing oxide is a hafnium silicate (Hf _1-x Si _x O _y , Hf _1-x Si). _x O _y n _z), hafnium aluminate _{(Hf 1-x Al x O} m, Hf 1-x Al x O m n n) ( provided that, x, y, z, m , n, is 0 <x <1 0 <y ≦ 2, 0 <z ≦ 1.33, 0 <m ≦ 1.5, and 0 <n ≦ 1), and the pressure during cleaning is in the range of 20.0 to 101.3 kPa so A method for cleaning a hafnium-containing oxide.