Yttrium Aluminum Silicate Glass Ceramic Coating For Semiconductor Chamber Apparatus

Abstract

Articles may be protected against halide plasma, by applying a rare earth-containing glaze to the surface of the article. The glaze may be a coating comprising; 20 to 90 mol % SiO.sub.2, 0 to 60 mol % Al.sub.2O.sub.3, 10 to 80 mol % rare earth oxides and/or rare earth fluorides (REX), wherein SiO.sub.2+Al.sub.2O.sub.3+REX60 mol %.

Claims

1. A coating comprising: 20 to 90 mol % SiO.sub.2; 0 to 60 mol % Al.sub.2O.sub.3; and 10 to 80 mol % rare earth oxides and/or rare earth fluorides (REX), wherein SiO.sub.2+Al.sub.2O.sub.3+REX60 mol %, and wherein the rare earth fluorides are present in an amount of at least 5 mol %.

2. The coating of claim 1, wherein the amount of rare earth elements in mol % is greater than the amount of Al in mol %.

3. The coating of claim 1, wherein the molar % of SiO.sub.2 is greater than the molar % of Al.sub.2O.sub.3.

4. (canceled)

5. The coating according of claim 1 wherein the coating comprises: TABLE-US-00008 20 to 90 mol % SiO.sub.2; 0 to 40 mol % Al.sub.2O.sub.3; and 10 to 80 mol % REX[[,]].

6. The coating of claim 4, wherein coating comprises: TABLE-US-00009 40-80 mol % SiO.sub.2; 5-20 mol % Al.sub.2O.sub.3; and 15-55 mol % REX.

7. The coating of claim 6, wherein coating comprises: TABLE-US-00010 50-75 mol % SiO.sub.2; 5-9.9 mol % Al.sub.2O.sub.3; and 15-40 mol % REX.

8. The coating of claim 1, wherein REX comprises yttrium oxide and/or yttrium fluoride.

9. The coating of claim 1, further comprising fluorides of one or more of Y, La, Zr, Sc, Nd, Ce and Al.

10. The coating of claim 1, wherein SiO.sub.2+Al.sub.2O.sub.3+REX comprise 95 mol % or more of the coating.

11. The coating of claim 1, further comprising less than 0.5 mol % of alkali metal, expressed as an oxide.

12. The coating of claim 1, further comprising ZrO.sub.2 in an amount up to 20 mol %.

13. The coating of claim 1, comprising less than 10 mol % of transition metal(s), expressed as an oxide.

14. The coating of claim 1, further comprising MgO in an amount up to 20 mol %,

15. A glaze precursor mixture comprising a composition to produce a coating of claim 1.

16. A coated article comprising a coating according to of claim 1.

17. The coated article according to claim 15, wherein the article comprises alumina or aluminum nitride.

18. -30. (canceled)

31. A coated article for use in environments where exposure to plasma is to be expected, comprising a plasma resistant rare earth-containing glaze applied to the surface of the article, wherein rare earth fluorides are present in an amount of at least 5 mol %.

32. (canceled)

33. A coated article, as claimed in claim 31, in which the coated article is an article for use in semiconductor manufacture.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 is a photograph image of a yttrium aluminum silicate (YAS) coating over an alumina substrate according to one embodiment of the present invention (Example 1);

[0041] FIG. 2 is the SEM-EDS image and analysis results for the coating in FIG. 1.

[0042] FIG. 3 is a photograph image of a YAS coating over an alumina nitride substrate according to another embodiment of the present invention (Example 2).

[0043] FIG. 4 is a cross-sectional image of the YAS coating of FIG. 3.

[0044] FIG. 5 is a photograph image of a YAS coating over an alumina substrate sintered at 1650 C for 2 hours according to a further embodiment of the present invention (Example 3).

[0045] FIG. 6 is the SEM-EDS image and analysis results for the coating in FIG. 5.

[0046] FIG. 7 is the SEM-EDS image and analysis results for a YASF coating over a sintered alumina article in Example 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0047] The working of the invention is detailed through the following non-limitative examples:

EXAMPLE 1

YAS Coating Over Sintered Alumina Part

[0048] a. Slurry preparation: 50 g of 523 SB (Wesgo brush paint vehiclea non-aqueous solvent based lacquer forming carrier having a viscosity in the range 100-120cPs at 24 C. and comprising alkyl cellulose in a mixed hydrocarbon/ketone solvent) is mixed with 50 g of Y.sub.2O.sub.3 powder (39RInframat Advanced Material, 99.995% Y.sub.2O.sub.3), 50 g SiO.sub.2 powder (Morgan internal ground SiO.sub.2) and 10 g of Al.sub.2O.sub.3 (99.8% pure, CT3000, Almatis). The slurry is milled with alumina media on a roll miller for one hour. This composition is equivalent to a target inorganic composition of 19.2 mol % rare earth oxide, 72.3 mol % SiO.sub.2, and 8.5 mol % Al.sub.2O.sub.3. [0049] b. Apply coating over alumina parts via spin coat at 60 RPM. Samples were dried at room temperature for 4 hours before put inside the 80 C oven for 1 hour.

[0050] Samples were sintered at 1550 C for 15 minutes in an air furnace. Optical micrograph and SEM-EDS analysis of the coating after firing is shown in FIG. 1 and FIG. 2, respectively. A few YAS based crystals were seen on the surface of the glaze coating. The surface roughness (Ra) of the glass coating is 1-3 micro inches (0.025-0.075 m).

EXAMPLE 2

YAS Coating Over Sintered AlN Part

[0051] a. Slurry preparation: 50 g of 523 SB (Wesgo brush paint vehicle) is mixed with 50 g of Y.sub.2O.sub.3 powder (39RInframat Advanced Material, 99.995% Y.sub.2O.sub.3), 50 g SiO.sub.2 powder (Morgan internal ground SiO.sub.2) and 10 g of Al.sub.2O.sub.3 (99.8% pure, CT3000, Almatis). The slurry is milled with alumina media on a roll miller for one hour. [0052] b. Apply Y.sub.2O.sub.3 coating over AlN parts via spin coat at 60 RPM. Samples were dried at room temperature for 4 hours before put inside the 80 C oven for 1 hour.

[0053] Samples were sintered at 1550 C for 15 minutes in a N2 furnace. Optical micrograph and cross-sectional view of the coating after firing is shown in FIGS. 3 and 4, respectively. It can be observed that application of the coating results in a coating with a reduced surface roughness in comparison with the sintered aluminum nitride, with surface roughness (Ra) of less than 1 m.

EXAMPLE 3

YAS Coating Over Alumina Substrates

[0054] Same coating composition as described on example 1 was applied over alumina based substrates. Samples were dried at 80 C for one hour followed by sintering in an air furnace to 1650 C for 2 hours. The surface morphology and SEM-EDS analysis of the coating is shown on FIGS. 5 and 6, respectively. The high temperature heat treatment created glass-ceramic coating and have more YAS based crystals formed on the surface. Although the surface finish of glass-ceramic coating is not as good as the glaze like coating shown on FIG. 1 but the glass ceramic coating still has good surface finish without any subsurface damage or grain pull-out features of the typical machined ceramics. The glass ceramic coating had a surface roughness of about 30-60 microinches (0.76-1.5 m).

EXAMPLE 4

YASF Coating Over Sintered Alumina Part

[0055] a. Slurry preparation: 50 g of 523 SB (Wesgo brush paint vehicle) is mixed with 50 g of Y.sub.2O.sub.3 powder (39RInframat Advanced Material, 99.995% Y.sub.2O.sub.3), 50 g SiO.sub.2 powder (Morgan internal ground SiO.sub.2), 50 g of YF.sub.3 (99.9% pure, Inframat Advanced Materials) and 10 g of Al.sub.2O.sub.3 (99.8% pure, CT3000, Almatis). The slurry is milled with alumina media on a roll miller for one hour. This composition is equivalent to a target inorganic composition of 14.8 mol % rare earth oxide, 22.9% rare earth fluoride, 55.7 mol % SiO.sub.2, and 6.6 mol % Al.sub.2O.sub.3. [0056] b. Apply coating over alumina parts via spin coat at 60 RPM. Samples were dried at room temperature for 4 hours before put inside the 80 C oven for 1 hour.

[0057] Samples were sintered at 1500 C for 15 minutes in a N.sub.2 furnace. SEM-EDS analysis of the coating after firing is shown in FIG. 7. It suggests that the addition of YF3 to glass decreases the Si content and increases Y content of the glaze, so that there is a significant amount of F present in the glaze.

[0058] It is believed that the addition of YF3 significantly increased the glass formation range of the YAS glass, it also increase the coefficient of thermal expansion (CTE) of the glass to have a better match with the alumina substrate.

[0059] The CTE of YAS glass shown in example 1 has CTE 5 ppm/K slightly lower than the alumina substrate (CTE 7 ppm/K), therefore a thick coating may resulted in cracking. The addition of fluoride into the YAS glass increased the CTE of glass (CTE of YF.sub.3 and Y.sub.2O.sub.3 are 13 ppm/K and 7 ppm/K; respectively).

[0060] In addition, under fluorine attack one mole of Y.sub.2O.sub.3 would lead to two moles of YF.sub.3. The molecular weight of Y.sub.2O.sub.3 is 225.81 g/mol and its density is 5.01 g/cm.sup.3 so the molar volume is 45.1 cm.sup.3/mol. The molecular weight of YF.sub.3 is 145.9 g/mol and its density is 4.01 g/cm.sup.3 so the molar volume is 36.4 cm.sup.3/mol. This means that fluorinating a mole of Y.sub.2O.sub.3 completely to YF3 would lead to an increase in molar volume from 45.1 cm.sup.3/mol to 72.8 cm.sup.3/mol. By incorporating YF.sub.3 into the material, the volume change consequent on fluorine attack will be reduced. This, in combination with the closer matching of CTE to alumina, leads to a lessened propensity to crack after fluorine attack.

FURTHER EXAMPLES

[0061] Table 1 shows further materials used as coatings and particularly to coat alumina and aluminum nitride substrates.

TABLE-US-00003 TABLE 1 Sample reference YASH YAG YAS YASM YASZ YASF Mole % Al2O3 51.1% 58.5% 20.7% 19.8% 19.1% 34.9% compound SiO2 15.7% 8.6% 62.4% 59.9% 61.9% 36.1% MgO 0.0% 0.0% 0.0% 5.6% 0.0% 0.0% ZrO2 0.0% 0.0% 0.0% 0.0% 4.6% 0.0% Y2O3 33.2% 33.0% 16.9% 14.6% 14.5% 19.5% YF3 0.0% 0.0% 0.0% 0.0% 0.0% 9.5% REX 33.2% 33.0% 16.9% 14.6% 14.5% 29.0% Sintering 1675 1743 1500 1500 1500 1450 Temperature ( C.)

[0062] These materials had different attributes.

[0063] As mentioned with respect to Example 4, the presence of fluorine (YASF) leads to a lessened propensity to crack after fluorine attack.

[0064] Zirconia addition (YASZ) and MgO addition (YASM) also provides better crack resistance, in part through the ability to tailor CTE with substrates.

[0065] In addition, both zirconia and MgO lower viscosity permitting good flow of the coating.

[0066] Zirconia may be present in amounts up to 20 mol %, or up to 15 mol %, or up to 10 mol %, or up to 5 mol %.

[0067] MgO may be present in amounts up to 20 mol %, or up to 15 mol %, or up to 10 mol %, or up to 6 mol %.

[0068] Coatings within some embodiments may comprise:

TABLE-US-00004 40-80 mol % SiO.sub.2 5-40 mol % Al.sub.2O.sub.3 0.1-20 mol % ZrO.sub.2 and/or MgO 10-35 mol % REX

[0069] In contrast YASH had a higher viscosity, enabling selected areas of substrate to be coated, but importantly also showed a very low etch rate. In particular, the YASH coating displayed a significantly lower etch rate when compared to the YAS sample, when assessed using comparable methodology to that described in US2009/0214825 (table one; FIG. 7b; and associated text). Within some YASH embodiments, coatings may comprise:

TABLE-US-00005 5-20 mol % SiO.sub.2 40-60 mol % Al.sub.2O.sub.3 20-55 mol % REX

[0070] In the examples a lacquer forming carrier was used, but this is not essential. Other carriers (for example terpineol oil, isopropyl alcohol, acetone, or inks) may be used to deliver the glaze precursors to the surface of the article.

[0071] Components other than SiO.sub.2, Al.sub.2O.sub.3, and rare earth oxides and fluorides may be present. The amount of such other components may be as much as 40 mol % or less than 30 mol %, less than 20 mol %, less than 10mol % or less than 5mol %. SiO.sub.2+Al.sub.2O.sub.3+REX may be 60 mol %, 70 mol %, 80 mol %, 85 mol %, 90 mol %, or 95 mol %.

[0072] In addition to the claimed ranges, the coatings may comprise

TABLE-US-00006 20-80 mol % SiO.sub.2 2-40 mol % Al.sub.2O.sub.3 20-55 mol % REX
or

TABLE-US-00007 20-40 mol % SiO.sub.2 10-40 mol % Al.sub.2O.sub.3 20-40 mol % REX

[0073] For use in semiconductor manufacture it is preferable (although not essential) that the alkali metal content (if present) be kept low, for example, expressed as oxide, at less than 0.5 mol %, less than 0.1mol % or even lower.

[0074] To facilitate glass formation it is preferable (although not essential) that any transition metals (if present) be kept low, for example, expressed as oxide, at less than 10mol %, less than 5mol %, less than lmol % or even lower.

[0075] In contrast to the coating of the present invention, conventional plasma sprayed Y.sub.2O.sub.3 coating has a relatively rough surface, but after polishing the surface roughness reduces to about 8 microinches (0.2 m). The polished surface typically has about 3% open porosity within the coating with the surface comprising small pores and residual particles that affect performance.

[0076] The presently disclosed coatings not only provide a halogen-plasma resistant coating, they also provide a dense and smooth surface leading to low particle contamination and easy cleaning.