WO2009031841A2

WO2009031841A2 - Method of coating metallic material

Info

Publication number: WO2009031841A2
Application number: PCT/KR2008/005233
Authority: WO
Inventors: Jae-Seung Jo; Sung-In Park; Jung-Ho Kim
Original assignee: Jeis Co., Ltd.
Priority date: 2007-09-05
Filing date: 2008-09-04
Publication date: 2009-03-12
Also published as: KR100820744B1; TWI421373B; WO2009031841A3; TW200923129A

Abstract

Disclosed is a coating method of tungsten to metal substrate comprising the steps of: anodizing a metal substrate including Al or Al-alloy to form an anodic oxidation layer, electroplating or electroless plating the metal substrate to form a tungsten layer on the anodic oxidation layer, and heating. By the coating method, the product manufactured by Al or Al-alloy has a high corrosion resistant, plasma resistant, and heat- and abrasion resistant, resulting in improvement of lifetime and reduction of contaminant of an autoclave, electrode or its accessories in semiconductor industry.

Description

METHOD OF COATING METALLIC MATERIAL

[TECHNICAL FIELD]

The present invention relates to a coating method of tungsten to metal used in manufacturing an autoclave or electrode accessories in semiconductor and TFT-LCD industry having plasma resistant, heat- and abrasion resistant and corrosion resistant, resulting in improvement of lifetime and reduction of contaminant.

[BACKGROUD ART]

Semiconductor and TFT-LCD is manufactured using an electrode in autoclave with injecting gases for etching or deposition process. The etching process is carried out under activated plasma by supplying, and deposition process such as chemical vapor deposition performs at high temperature to deposit a material on a substrate.

Al and its alloy used as a material for an autoclave and electrode may be exposed to caustic plasma at high temperature. Therefore these Al materials tend to corrode or crack; more seriously, reduce a lifetime caused by particles generated from Al materials. In addition, by inserting these Al materials products into a semiconductor to TFT-LCD substrate, it brings out poor quality and operation stops.

Therefore, in order to enhance plasma resistant and heat- and abrasion- resistance standing in extreme condition of autoclave, diverse methods have been tried regarding treatment of Al-materials. US Patent NO. 5,641 ,375 discloses anodizing technique for reducing plasma corrosion and wear on a chamber wall made of Al-materials, which an anode oxidation layer is formed on the chamber wall through anodizing i technique. In anodizing, controlling a thickness of the anode oxidation layer may enhances some properties such as plasma resistant and heat- and abrasion resistance, however, severe damage on the layer may happen by plasma corrosion Japan patent Laid-Open Publication No. 62-103379 refers to forming a corrosion resistant layer such as AI₂O₃, AIC, TiN, TiC, and AIN on Al- materials. Plasma resistant property improved by inducing the corrosion resistant layer, but the method brings about crack caused by low adhesion with Al materials. In addition, method of coating CT₂O₃ on the surface of Al-materials was suggested, but the method was not sufficient to improve corrosion resistant.

Korea patent Publication No. 2000-59295 discloses a tungsten coating method on the surface of metal by electroplating to enhance surface hardness and corrosion resistant, and so on. Korea patent Publication No. 2004-272 suggests a wet electroless plating a metal including W, Pd, Ni or P on the surface of Al-alloy material.

As illustrated-above, by coating of tungsten it is possible to enhance plasma resistant of articles made of Al materials. Since electroplating for coating tungsten is carried out under high temperature, it creates crack, separation, bubble caused by the differences of heat expansion property between Al and tungsten, resulting in another problem of generating particles rapidly from articles.

Korea patent Publication No. 2005-22184 teaches an improvement method of lifetime by forming first nickel layer/second nickel layer/tungsten layer/third nickel layer/rhodium layer on a metal module of semiconductor equipment, in order. In this method, although demerits with corrosion resistant of metal module and exfoliation of layers were solved, there are still problems such as complicated processes and high cost due to multi layers fabrication.

[DISCLOSURE] [TECHNICAL PROBLEM]

It is an object of the present invention to provide a coating method to a metal, especially Al material used in manufacturing an autoclave, electrode or its accessories, and the method enhances plasma resistant, heat- and abrasion resistant, and corrosion resistant, resulting in improvement of lifetime and reduction of contaminant.

It is another object of the present invention to provide a product used in semiconductor or TFT-LCD industry manufactured by the coating method.

[TECHNICAL SOLUTION] The present invention provides a coating method of tungsten on a metal substrate comprising the steps of: anodizing a metal substrate including Al or Al-alloy to form an anodic oxidation layer, electroplating or electroless plating the metal substrate to form a tungsten layer on the anodic oxidation layer, and heating.

The present invention also provides an additional electroplating step to form a nickel layer on the anode oxidation layer.

Further, the present invention provides an autoclave product for manufacturing semiconductor and TFT-LCD having an aluminum oxide layer and a tungsten layer on a surface. [ADVANTAGEOUS EFFECT]

By forming anode oxidation layer and tungsten layer on the surface of Al metal substrate, the metal improves plasma resistant, heat- and abrasion resistant and corrosion resistant, in accordance with the present invention

[DESCRIPTION OF DRAWINGS]

The invention will be described on conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram showing the step of the tungsten coating method to metal substrate in one embodiment of the present invention, and

FIGs. 2 to 4 are mimetic diagrams thereof.

FIG. 5 is a block diagram showing the step of the tungsten coating method to metal substrate in another embodiment of the present invention, and FIGs. 6 to 7 are mimetic diagrams thereof. FIG. 8 is a spectrum illustrating components in the surface of tungsten layer prepared in Example 1.

FIG. 9 is a top view showing tungsten layer prepared in Example 1. FIG. 10 is a cross-sectional view showing aluminum oxide layer/tungsten layer deposited on the aluminum substrate in Example 1. FIG. 11 is a graph illustrating corrosion resistant according to time of the products prepared in Examples 1 to 3 and Comparative Examples 1 and 2.

FIG. 12 is an image from scanning electron microscope of the tungsten layer prepared in Example 1. FIG. 13 is an image from scanning electron microscope of the nickel layer prepared in Comparative Example 1. FIG. 14 is an image from scanning electron microscope of the aluminum oxide layer prepared in Comparative Example 2.

[BEST MODE] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. Like numbers refer to like elements throughout.

Moreover, when a layer is on other layer, it may be contact therewith or added another layer between them.

FIG. 1 is a block diagram showing the step of the tungsten coating method to metal substrate in one embodiment of the present invention, and FIGs. 2 to 4 are mimetic diagrams thereof.

First, it is provided a metal substrate (11 ) with Al or Al-alloy (see Fig 2). It is preferable that the metal substrate (11 ) is treated by a pre- treatment process including the steps of degassing, cleaning, etching and electrocleaning. The pre-treatment process comprises the steps of a cleaning (or degreasing) process using a cleaning solution at 60~80 ⁰C to remove oil dust in the surface for forming a layer; a washing process to eliminate the cleaning solution and contaminants; etching process to increase surface area of the metal substrate (11 ); and electrocleaning process. Suitable process such as sonication can be added or substituted with the above-mentioned process, as well known in this art. Next, it performs anodizing to form an anodic oxidation layer with pore on the surface of the metal substrate (11 ).

In carrying out the anodizing, the metal substrate (11 ) is used as a positive electrode, and immersed in an electrolyte with acids, and applied a voltage.

By the voltage, the metal substrate (11) is gradually oxidized from its surface, and an anode oxidation AI₂O₃ layer forms on the metal substrate (11 ). As further supplying the voltage, in the formed anodic oxidation layer (13) exist vertical nanopores with direction to the metal substrate (11 ). The electrolyte suitable for anodizing is preferably selected from the group consisting of phosphoric acid, oxalic acid, sulfuric acid, organic, and a mixture thereof. It is preferred to use as a diluted solution, more preferably as an aqueous solution having 15 — 18 wt% of sulfuric acid, or 1 ~5 wt% of oxalic acid. The anodizing is carried out by supplying a voltage of 0.1 to 100 at the temperature of 25 to 100⁰C for 0.5 to 5 hours. These conditions can be varied by the skilled person in this art considering parameters such as variety of acids, diameter of nanopore, degree of order, and so on.

It is desirable that the anodizing step is repeated, preferably 2 or 4 times, to increase the degree of order of nanopore.

The anodic oxidation layer (13) has not fully crystalline, but amorphous- structure of AI₂O₃. Because of growing the anodic oxidation layer (13) toward and outer the metal substrate (11 ) half and half, there is no crack with metal substrate (11 ) even though the layer (13) has a ceramic property. In comparison with this, AI₂O₃ layer with fully crystalline structure, which is prepared by blazing, has ceramic property, so thus show serious crack due to about 4 times difference with heat expansion co-efficiency to Al mother metal. After anodizing, in order to increase performance of electroplating, it performs a cleaning process. It is desirable that the cleaning process should be handled carefully thorough whole processes, because the electroplating is hypersensitive. Next, it performs electroplating or electroless plating to form a tungsten layer (15) on the anodic oxidation layer (13) (see FIG. 4).

It is well known that tungsten makes the property of metal, especially metal substrate (11 ), because of having high corrosion resistant, plasma resistant, and heat- and crack resistant. In a preferred embodiment of the present invention, a tungsten layer

(15) forms on the anodic oxidation layer (13). As shown in FIG. 3, tungsten exists in the pore of the anodic oxidation layer (13), and also tungsten is coated thereon. Therefore, the adhesion between the metal substrate (11 ) and tungsten layer (15) enhances. The tungsten layer (15) may form by electroplating or electroless plating.

The electroplating performs by supplying a current density of 1 — 10

A/dm² at a temperature of 75~85°C using an aqueous solution of pH 6 — 7.

Suitable aqueous solution includes Na₂OWO₃-H₂O (5— 50g/l), Na₂CO₃ (10~30g/l), NH₄OH (1 ~15g/l), CH₂OHCOONa (1 ~5g/l), and Na₃C₆H₅O₇

(20~50g/l).

The electroless plating performs using an aqueous solution at a temperature of 80—90 ⁰C with adjusting pH 8- 10. Suitable the aqueous solution includes Na₂WO₄ -2H₂O (10~30g/l), NiCI₂-6H₂O (5~ 15g/l), NaH₂PO₂-H₂O (10~30g/l), CH₂OHCOONa (5~ 15g/l), Na₃C₆H₅O₇ (5~ 10g/l),

CH₄N₂S (5~ 10g/l), Na₂CO₃ (10~25g/l), NH₄NF₂ (5- 15%). It is preferable to carry out electroplating or electroless plating until the tungsten layer (15) has a thickness of 5~50μm. When the thickness is less than the above range, plasma resistant is drastically declined. On the contrary, when the thickness is over the above range, it brings out bubble or separation at interface between the metal substrate (11 ) and tungsten layer

(15).

After forming the tungsten layer (15), it performs washing and drying process.

Next, the metal substrate (11 ) having the anode oxidation layer (13) and tungsten layer (15) is heat-treated.

The heating process proceeds under oxidation or reduction atmosphere at the temperature of 350—600 ⁰C, and this heating process makes improves the density and adhesion of the tungsten layer (15). When the temperature is less than the above rage, the mechanical property of the tungsten layer (15) lessens. On the contrary, when the temperature is over the above range, it brings out a damage of metal substrate and crack of the anodic oxidation layer.

As illustrated-above, the metal substrate (11 ) of the present invention has enhanced plasma resistant and anti heat- and abrasion resistant by forming the porous anode oxidation layer (13) thereon, which is prepared by oxidizing. Further, the tungsten layer (15) on the anode oxidation layer (13) has improved corrosion resistant. Due to tungsten present in pores of the anode oxidation layer (13), the separation of between the anode oxidation layer (13) and tungsten layer (15) effectively reduces. Also, the method of the present invention dose not needs any additional zincate's process or adhesion layer, which is required in the prior art, thus the method of the present invention subsequently simplifies overall process and lessens cost.

Additionally, in accordance with the present invention, it further performs forming a nickel layer on the anode oxidation layer by electroplating. The nickel layer located in between the anode oxidation layer and tungsten layer enhances interfacial adhesion with these layers and adhesion potential between them.

FIG. 5 is a block diagram showing a step of the tungsten coating method to metal substrate in the second embodiment of the present invention, and FIGs. 6 to 7 are mimetic diagrams thereof.

In the concrete, it performs anodizing to form the anode oxidation layer on the surface of the metal substrate.

Here, the detail description of the anodizing follows the above- mentioned embodiment of the present invention. Next, it performs electroplating of the metal substrate (11 ) having anode oxidation layer (13) to form nickel layer (17) (see FIG. 7).

The electroplating performs by supplying a current density of 1 —20 A/dm² at a temperature of 40—80⁰C using an aqueous solution of pH 8- 10. Suitable aqueous solution includes NiSO₄-6H₂O (100~500g/l), NiCI₂-6H₂O (20 - 80g/l), and H₃BO₃ (20 ~ 50g/l).

Referring to FIG. 6, nickel exists in the pore of the anode oxidation layer (13), and nickel is coated thereon, resulting in formation of nickel layer

(19). By this structural benefit, interface adhesion between the metal substrate (11 ) and nickel layer (17) enhances. After forming the nickel layer (17) is followed by forming a tungsten layer (19).

Next, it performs electroplating or electroless plating to form the tungsten layer (19) on the nickel layer (17) (See FIG. 7). The tungsten layer (19) may form by electroplating or electroless plating, as the above-described embodiment of the present invention.

Next, it performs heating of the metal substrate.

Before heating step, it is preferable to form the tungsten layer (19) and to carry out a drying process subsequently.

As noted above, in accordance with the present invention, the anode oxidation layer/tungsten layer or anode oxidation layer/nickel layer/tungsten layer on the surface of metal substrate forms, in order.

The surface treatment according to the coating method of metal substrate of the present invention can be used as a technique for manufacturing a product such as an autoclave, heater used in an autoclave for semiconductor and TFT-LCD industry, showerhead (diffuser), and so on

The product is mainly comprised of Al or Al alloy. Therefore by coating tungsten on the surface of the product, corrosion resistant, plasma resistant and anti-heat- and crack property improves. Like this, it is advantageous that the method of the present invention makes tungsten on the product maximize its beneficial property, and increase interface adhesion between the tungsten layer and product. Moreover, due to simplifying overall process, the method of the present invention has advantages in terms of a high performance and low cost, in comparison with the prior art.

The invention will now be further described with reference to a number of specific examples, which are to be regarded solely as illustrative and not as restricting the scope of the invention.

[MODE FOR INVENTION]

Example 1 An Al substrate was carried out pre-treatment comprising degassing, washing, etching and electrocleaning, as know in this art.

The Al substrate was subjected to 0.5 M acid solution including sulfuric acid: oxalic acid (1 :5 weight ratios). Using the Al substrate as an anode, anodizing was carried out supplying the current density of 2A/ciif at the temperature of 28⁰C for 60 minutes to form AI₂O₃ layer.

After washing the Al substrate with Dl water, it was subjected to electroless plating bath for forming a tungsten layer. The bath was containing Na₂WO₄ -2H₂O (30g/l), NiCI₂-6H₂O (5g/l), NaH₂PO₂-H₂O (12g/l), CH₂OHCOONa(5.5g/l), Na₃C₆H₅O₇ (10g/l), CH₄N₂S (5g/l), Na₂CO₃ (15g/l), and NH₄NF₂ (12%). With adjusting pH 10, electroless plating was carried out at the temperature of 90⁰C for 30 minutes with stirring, resulting in formation of the tungsten layer with the thickness of 25/zm on AI₂O₃ layer.

After washing with water, it was dried at room temperature for 1 hour, and heating was carried out at the temperature of 400⁰C for 2 hours under oxygen atmosphere.

Example 2

An Al substrate was carried out pre-treatment comprising degassing, washing, etching and electrocleaning, as know in this art.

The Al substrate was subjected to 0.5 M acid solution including sulfuric acid: oxalic acid (1 :5 weight ratios). Using the Al substrate as a anode, anodizing was carried out supplying the current density of 2A/cnf at the temperature of 28⁰C for 60 minutes to form AI₂O₃ layer. After washing the Al substrate with Dl water, it was subjected to electroplating bath for forming a tungsten layer. The bath was contained Na₂OWO₃-H₂O (20g/l), Na₂CO₃ (I Og/!), NH₄OH (5g/l), CH₂OHCOONa (1 g/l), and Na₃C-₆H₅O₇ (15g/l). With supplying the current density of 5A, electroplating was carried out for 40 minutes to form a tungsten layer with the thickness of 25μm on AI₂O₃ layer.

After with washing water, it was dried at room temperature for 1 hour, and heating was carried out at the temperature of 400⁰C for 2 hours under oxygen atmosphere.

Example 3

The Al substrate was subjected to 0.5 M acid solution including sulfuric acid: oxalic acid (1 :5 weight ratios). Using the Al substrate as a anode, anodizing carried out supplying the current density of 2A/cnf at the temperature of 28⁰C for 60 minutes to form AI₂O₃ layer. After washing the Al substrate with Dl water, it was subjected to electroplating bath for forming a nickel layer. The bath was contained NiSO₄-6H₂O (400g/l), NiCI₂-6H₂O(20g/l), and H₃BO₃(30g/l). With supplying the current density of 2OA, electroplating was carried out for 10 minutes to form a nickel layer with the thickness of 15μm on AI₂O₃ layer. After with washing water, the Al substrate was subjected to electroplating bath for forming tungsten layer. The bath was contained Na₂OWO₃-H₂O (20g/l), Na₂CO₃ (IOg/!), NH₄OH (5g/l), CH₂OHCOONa (1g/l), and Na₃C₆H₅O₇ (15g/l). Supplying with the current density of 5A, electroplating was carried out for 40 minutes to form a tungsten layer with the thickness of 30μm on the nickel layer.

After drying at 40 "C for 4 hours, heating was carried out at the temperature of 400⁰C for 4 hours under oxygen atmosphere. Comparative Example 1

An Al substrate was carried out pre-treatment comprising degassing, washing, etching and electrocleaning, as know in this art. After washing the Al substrate with Dl water, it was subjected to electroplating bath for forming a nickel layer. The bath was contained NiSO₄-6H₂O (400g/l), NiCI₂-6H₂O(20g/l), and H₃BO₃(30g/l). With supplying the current density of 2OA, electroplating was carried out for 10 minutes to form a nickel layer with the thickness of 5μm.

Comparative Example 2

The Al substrate was subjected to 0.5 M acid solution including sulfuric acid: oxalic acid (1 :5 weight ratios). Using the Al substrate as a anode, anodizing was carried out supplying the current density of 2A/cnf at the temperature of 28⁰C for 60 minutes to form AI₂O₃ layer.

Experimental Example 1 To ascertain the formation of the tungsten layer by prepared in

Example 1 , it observed using SEM (scanning electro microscopy) and EDAX

(Energy Dispersive Spectroscopy), referring to FIG. 8.

FIG. 8 is a spectrum illustrating components in the surface of tungsten layer prepared in Example 1. As seen from FIG. 8, it is understood that about 30% of tungsten were formed on AI₂O₃ layer. FIG. 9 is a top view showing tungsten layer prepared in Example 1 , and

FIG. 10 is a cross-sectional view showing aluminum oxide layer/tungsten layer deposited on the aluminum substrate in Example 1. As shown in FIGs.

9 and 10, it was observed that AI₂O₃ layer and a tungsten layer were form on Al metal substrate, in order.

Experimental Example 2: corrosion resistant measurement

To observe corrosion resistant of products prepared in Examples 1 to 3 and Comparative Example 1 and 2, the products were immersed into 10% HCI aqueous solution (25⁰C) to measure corrosion resistant according to time.

The results are shown in following FIG. 11.

FIG. 11 is a graph illustrating corrosion resistant according to time of the products prepared in Examples 1 to 3 and Comparative Examples 1 and 2. Referring to FIG. 11 , it is understood that the corrosion generated at the surface of products of Examples 1 to 3 is very little, in comparison with that of comparative Examples 1 and 2, although the coating loss shows the tendency to increase by time.

Experimental Example 3: plasma resistant measurement To determine plasma resistant of products prepared in Examples 1 to 3 and Comparative Example 1 and 2, the products were subjected to PECVD chamber and generated plasma using NF₃ at the temperature of 380⁰C to observe damage on surface. Table 1 shows the results.

[Table 1 J structure 24 hours 48 hours 96 hours example 1 substrate/anode oxidation No damage No damage No damage

Experimental Example 4: heat- and abrasion resistant measurement

To determine anti heat- and abrasion resistant of products prepared in Examples 1 to 3 and Comparative Example 1 and 2, it was repeatedly ten times carried out the process of heating to 500 ^°C/cooling in water at room temperature, and the surface of resultant was observed by SEM.

Referring to FIG. 12, it is understood that the tungsten layer prepared by the present invention has no crack. In comparison with this result, it is observed that products having single nickel layer or AI₂O₃ layer on Al substrate showed crack, as illustrated in FIGs. 13 and 14.

[INDUSTRIAL APPLYCABILITY]

The surface treatment of metal substrate according to the present invention can be used as a technique for manufacturing products such as an autoclave, heater used in an autoclave for semiconductor and TFT-LCD industry, showerhead (diffuser), and so on.

Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made without departing from the spirit or scope of the appended claims

Claims

[CLAIMS] [CLAIM 1 ]

A coating method of tungsten on a metal substrate comprising the steps of: anodizing a metal substrate including Al or Al-alloy to form an anodic oxidation layer, electroplating or electroless plating the metal substrate to form a tungsten layer on the anodic oxidation layer, and heating, wherein the electroplating performs by supplying a current density of

1 ~ 10 A/dm² at a temperature of 75 —85⁰C using an aqueous solution of pH 6-7, which the aqueous solution includes Na₂OWO₃ H₂O (5~50g/l), Na₂CO₃ (10~30g/l), NH₄OH (1 ~ 15g/l), CH₂OHCOONa (1 ~5g/l), and Na₃C₆H₅O₇ (20~50g/l), and the electroless plating performs using an aqueous solution at a temperature of 80—90 ⁰C with adjusting pH 8- 10, which the aqueous solution includes Na₂WO₄ -2H₂O (10~30g/l), NiCI₂-6H₂O (5~ 15g/l), NaH₂PO₂-H₂O (10~30g/l), CH₂OHCOONa (5~ 15g/l), Na₃C₆H₅O₇ (5~ 10g/l), CH₄N₂S (5~ 10g/l), Na₂CO₃ (10~25g/l), and NH₄NF₂ (5 - 15%).

[CLAIM 2]

The coating method according to claim 1 , wherein the anodizing is carried out by supplying a voltage of 0.1 to 100 V in an electrolyte including an acid selected from the group consisting of phosphoric acid, oxalic acid, sulfuric acid, and a mixture thereof, under 25 to 10O⁰C for 0.5 to 5 hours.

[CLAIM 3]

The coating method according to claim 1 , wherein the heating is carried out at 350 to 600⁰C .

[CLAIM 4]

The coating method according to claim 1 , further performs a step of forming nickel layer on the anodic oxidation layer by electroplating.

[CLAIM 5] The coating method according to claim 4, wherein the nickel layer is formed by supplying a current density 1 ~ 10A/dm² under 40—80 ^°C using a coating solution of pH 8~ 10, which the coating solution includes NiSO₄-6H₂O (100~500g/l), NiCI₂-6H₂O (20~80g/l), and H₃BO₃ (20 ~50g/l).

[CLAIM 6]

An autoclave product for manufacturing semiconductor and TFT-LCD having an aluminum oxide layer and a tungsten layer on a surface, orderly, formed by claim 1.

[CLAIM 7]

The autoclave product according to claim 6, further inserts a nickel layer into between the aluminum oxide layer and tungsten layer.