KR100856592B1 - Cooling block and plasma processing apparatus - Google Patents

Abstract

The present invention provides a cooling block for constituting an electrode for generating a plasma used for plasma processing, wherein the cooling block satisfies a function required for the electrode while suppressing corrosion and providing a long service life. The zinc is formed by joining each of the first base material and the second base material each made of aluminum and at least one of which is formed with a recess for forming a flow path of the cooling liquid under a heating atmosphere containing oxygen in a state where zinc is interposed therebetween. The cooling block is formed by simultaneously forming an anticorrosive layer composed of a diffusion bonding layer and a zinc oxide film diffused in aluminum. In addition, the amount of zinc in the zinc oxide film is preferably 30 g or more per square meter, and further, a solder material such as nickel may be interposed between the first and second base materials.

Description

COOLING BLOCK AND PLASMA PROCESSING APPARATUS}

1 is a cross-sectional view showing a RIE plasma etching apparatus to which a cooling block according to an embodiment of the present invention is applied;

2 is an enlarged plan view of the cooling block of the apparatus of FIG. 1;

3 is an enlarged cross-sectional view of a cooling block of the apparatus of FIG. 1;

4 is an explanatory diagram showing a manufacturing method of the cooling block;

5 is an explanatory diagram showing a manufacturing method of the cooling block;

6 is an explanatory diagram showing a manufacturing method of another cooling block;

7 is an explanatory diagram showing a manufacturing method of another cooling block;

8 is an explanatory diagram showing the results of experiments performed to confirm the effects of the present invention;

9 is a schematic cross-sectional view showing a conventional plasma processing apparatus.

Explanation of symbols for the main parts of the drawings

W: wafer 2: processing container

3: support table 4: insulation plate

5: support 6: shower head

7: upper electrode 7a: electrode plate

71 gas discharge hole 8 base material

8a: 1st base material 8b: 2nd base material

80: cooling block 81: euro

82: gas discharge hole 90: cooling block

91: Zn coating film 92: Ni coating film

93 bonding layer 94 zinc oxide film

94a: lower plate 94b: upper plate

The present invention relates to a cooling block constituting an electrode for generating a plasma used for plasma processing, and a plasma processing apparatus using the cooling block.

In a manufacturing process such as a semiconductor device, plasma processing using plasma is often used. However, as shown in FIG. 9, the plasma processing apparatus for performing such a plasma processing includes a processing chamber 10 formed of a vacuum chamber. A mounting table 11 for combining a lower electrode inside and mounting a semiconductor wafer (hereinafter referred to as "wafer") W as a substrate, and a plurality of gas supplies provided above the mounting table 11. A shower head 12 having a hole 12a is provided. The lower surface of the shower head 12 constitutes an upper electrode 13, and a high frequency for plasma generation is applied from the high frequency power supply 15 between the upper electrode 13 and the mounting table 11 serving as the lower electrode. Plasma is generated in the processing space between the mounting table 11 and the upper electrode 13, thereby activating the processing gas introduced into the processing container 10 from the showerhead 12 by the plasma, thereby thereby mounting the mounting table. It is comprised so that the plasma process, such as an etching and a film-forming process, may be performed with respect to the wafer W mounted in (11). The upper electrode 13 is composed of an electrode plate 13a and a cooling block 13b.

The upper electrode 13 of the processing vessel affects the plasma processing. For example, in the case of plasma etching, the in-plane uniformity or the inter-plane uniformity of the etching rate of the wafer W is affected. The temperature control structure is also one of the factors, and it is required to equalize the upper temperature in the same diameter plane of the wafer W. As one of the structures satisfying this request, the upper electrode 13 is in contact with the processing region. The structure which arrange | positions the electrode plate 13a using the electrically-conductive material without ceramics or heavy metal contamination in the site | part, and stacks the cooling block 13b on this electrode plate 13a is known. Since the cooling block 13b is located in the gas atmosphere in vacuum, a complicated flow path connecting each gas supply hole 12a is required in order not to inhibit gas supply and to make the temperature uniform.

As the cooling block 13b, two metal plates are joined to each other by soldering, and those having a structure having a flow path 14 of a cooling liquid therein are used. The cooling block 13b requires high heat conduction performance in order to have a function as heat exchange, and high electric conduction performance in order to be a high frequency passage. Therefore, as a metal plate, stainless steel (henceforth "SUS") with high resistivity and thermal conductivity cannot be used, and aluminum (Al) whose resistivity and thermal conductivity is much lower than SUS is widely used.

However, when aluminum is used, since the pure aluminum surface is exposed in the flow path 14 contacting the coolant, the inner peripheral surface of the flow path 14 may be corroded by the coolant flowing through the flow path 14. There is a fear that the coolant is blocked in the flow path 14 due to the corrosion of the inner circumferential surface of (14). Here, it is necessary to use the flow path 14 formed in the cooling block 13b.

As such an anticorrosive method, a method of forming an aluminum oxide film on the inner circumferential surface of the flow path 14 by an anodizing process is considered. However, when anodizing the surface of the metal plate before soldering, the alumite is soldered at the time of joining the metal plate. Since it cannot withstand and a crack arises in an alumite, the function as an anticorrosive film is not fully exhibited. In addition, in the case of anodizing after soldering, an electrolyte solution for anodizing treatment must be flowed into the flow path 14, so that the electrolyte solution does not spread evenly due to the complexity of the flow path 14, so that no alumite is formed in the flow path 14. There is a possibility that a portion is formed, and a pinhole is formed. In addition, dissolved oxygen and alumite are combined in the flow passage 14, and there is a fear that foreign substances that block the flow passage 14 may precipitate.

In addition, in the method of coating the resin on the inner circumferential surface of the flow passage 14, the resin must be poured into the flow passage 14, and the resin does not spread widely due to the complexity of the flow passage 14. There is a fear that a portion that is not coated is formed and a pinhole is formed. Moreover, there remains a concern whether the thermal conductivity satisfying the function as the cooling block 13b can be obtained.

In addition, the method of installing the pipe in the cooling block 13b cannot be flexibly bent in the pipe itself, and cannot be adopted because it cannot withstand the soldering temperature (about 600 ° C.) at the time of construction.

In addition, applying a chiller eliminates the need to consider corrosion resistance, so that suitable materials such as aluminum and copper can be used, but are often difficult in terms of cost and space.

On the other hand, Patent Literature 1 discloses a flat tube using three composite materials of a solder material / aluminum alloy core material / Al-Zn-based alloy sacrificial material containing Si or the like in an automobile radiator. And electric welding, and the composite material is produced by applying a sacrificial agent to one side of the core material and hot rolling, etc., but the electrode for generating the plasma used in the plasma treatment is described. The cooling block WHEREIN: The suitable manufacturing method is not described.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-86295 (paragraph 0002 and paragraph 0019)

This invention is made | formed in view of such a situation, The objective is that the cooling block which comprises the electrode for generating the plasma used for a plasma process WHEREIN: It satisfies the function required for an electrode, suppresses corrosion, and has long service life. To provide a cooling block. Another object is to provide a plasma processing apparatus using such a cooling block.

The present invention constitutes an electrode for generating a plasma for use in plasma processing, the cooling block having a coolant flow path therein, each made of aluminum, and at least one of the recesses for forming the flow path of the coolant is processed The first base material and the second base material are bonded together in a heating atmosphere containing oxygen with zinc interposed therebetween, whereby an anticorrosive layer composed of a diffusion bonding layer in which zinc is diffused in aluminum and a zinc oxide film is formed at the same time. It is characterized by.

In the cooling block described above, the amount of zinc in the zinc oxide film is preferably 30 g or more per m 2. In addition, a structure in which a solder material selected from nickel, silicon, copper, boron, phosphorus, chromium, iron, and carbon may be interposed between the first base material and the second base material. Such a cooling block is formed as an upper electrode facing a lower electrode on which a target object is mounted, for example, a plurality of gas supply holes penetrating in the thickness direction for supplying a processing gas for plasma generation to a processing atmosphere. .

Moreover, in this invention, in the cooling block which comprises the electrode for generating the plasma used for a plasma process, and has the flow path of a cooling liquid inside, the plate of stainless steel is joined to the surface of the base material which consists of aluminum, respectively, The first member and the second member on which at least one of the recesses for forming a flow path of the cooling liquid are processed are joined to each other in a state where the plates are opposed to each other, and the joining portion of the plate of the first member and the plate of the second member The diffusion bonding layer of stainless steel is formed, The joining part of the base material and plate which consist of aluminum is characterized by the diffusion bonding layer of stainless steel and aluminum being formed. Similarly, for such a cooling block, a plurality of gas supply holes penetrating in the thickness direction are formed to supply the processing gas for plasma generation to the processing atmosphere, and at the same time, it can be used as an upper electrode facing the lower electrode on which the object is to be mounted. have. In this case, it is preferable that the inner peripheral part of the gas supply hole formed in the plate made of stainless steel is covered with aluminum of a base material.

Moreover, the plasma processing apparatus of this invention is equipped with the airtight processing container, the mounting table which is provided in the inside of this processing container, and combines the electrode for holding the board | substrate processed by plasma, and the said mounting table inside the said processing container. And a high frequency electric field formed between an electrode including the cooling block described above, a gas supply unit for introducing a processing gas into the processing container, the mounting table, and the electrode opposite to the processing gas. It characterized in that it comprises a plasma generating means for making a plasma. Further, in the plasma processing apparatus, the processing gas introduction means has a shower head for discharging gas from the plurality of holes, the electrode functions as a shower plate on the lower surface of the shower head, and the plurality of gas discharge holes It is configured to be formed.

(1st embodiment)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described. 1 is a cross-sectional view showing a reactive ion etching (RIE) plasma etching apparatus which is a plasma processing apparatus to which a cooling block according to an embodiment of the present invention is applied. Reference numeral 2 in FIG. 1 is a processing container (vacuum chamber) made of aluminum, for example. The processing container 2 consists of a small diameter cylindrical upper part 2a and a large diameter cylindrical lower part 2b, and is airtight. In this processing container 2, the support table 3 which is a mounting table which horizontally supports the semiconductor wafer W (henceforth "wafer") which is a to-be-processed substrate, and functions as a lower electrode is provided. The said support table 3 is comprised from aluminum, for example, and is supported by the support stand 5 of a conductor through the insulating plate 4. Further, a focus ring 31 formed of silicon (Si), for example, is provided on the outer circumference of the support table 3 above. The lower portion of the support 5 is covered with a cover 32. Moreover, the baffle plate 33 is provided in the outer side of the said support stand 5, and is electrically conductive with the processing container 2 via this baffle plate 33, the support stand 5, and the cover 32. As shown in FIG. In addition, the processing container 2 is grounded.

The ceiling wall portion of the processing container 2 is a shower head 6, which is a gas supply unit for introducing a processing gas into the processing container 2, and an upper surface of the shower head 6 functioning as a shower plate. The electrode 7 is provided. The upper electrode 7 is formed of, for example, a cylindrical cooling block 80 having a thickness of 20 mm using a conductive material free of contamination such as ceramics or heavy metal at a portion in contact with the processing region. The upper electrode 7 is provided to face in parallel with the support table 3 functioning as the lower electrode, and a plurality of gas discharge holes 71 are formed in the electrode plate 7a. That is, the support table 3 and the upper electrode 7 which are lower electrodes comprise a pair of parallel plate electrode. In addition, since the upper electrode 7 is a portion that emits electric force lines for plasmaizing the processing gas, the size of the upper electrode 7 is increased in order to generate a high in-plane uniformity plasma on the wafer W surface. The wafer W is formed to be the same size or larger than the surface to be processed. The upper electrode 7 is grounded via the processing container 2.

An exhaust port 21 is formed in the bottom wall of the lower part 2b of the processing container 2, and a vacuum pump 22 is connected to the exhaust port 21. The vacuum pump 22 is operated to reduce the pressure in the processing container 2 to a predetermined degree of vacuum. On the other hand, at the side wall of the upper part 2a of the processing container 2, the carrying in / out port 23 for carrying in / out of the wafer W is provided, and this carrying in / out port 23 is opened and closed by the gate valve 24, have.

The first high frequency power source 26 for plasma formation and the second high frequency power source 27 for ion intake are connected to the support table 3 via a matcher 28 and 25, respectively. High frequency power of a predetermined frequency is supplied to the support table 3 from the power source 26 and the second high frequency power source 27. The second high frequency power supply 27 supplies high frequency power lower than the frequency of the first high frequency power supply 26.

On the surface of the support table 3, an electrostatic chuck 34 for electrostatically holding and holding the wafer W is provided. The electrostatic chuck 34 has an electrode 34a interposed between the insulators 34b, and a DC power supply 35 is connected to the electrode 34a. The voltage is applied from the power source 35 to the electrode 34a, whereby the wafer W is adsorbed and held by an electrostatic force, for example, a coulomb force.

In addition, a cooling chamber 36 is provided inside the support table 3, and refrigerant is introduced into the cooling chamber 36 through the refrigerant inlet pipe 36a and discharged from the refrigerant discharge pipe 36b to circulate. The cold heat is then conducted to the wafer W via the support table 3, whereby the processing surface of the wafer W is controlled to a desired temperature.

In addition, even when the inside of the processing container 2 is exhausted by the vacuum pump 22 and maintained in a vacuum, a cooling gas is provided so that the wafer W can be effectively cooled by the refrigerant circulated in the cooling chamber 36. The gas introduction mechanism 37 is introduced between the front surface of the electrostatic chuck 34 and the back surface of the wafer W via the gas supply line 38. By introducing the cooling gas in this way, cooling heat of the refrigerant can be effectively transmitted to the wafer W, and the cooling efficiency of the wafer W can be increased.

The shower head 6 is provided with a gas inlet 72 at an upper portion thereof, and a space 73 for gas diffusion therein is formed therein. A gas supply pipe 74 is connected to the gas inlet 72, and a processing gas supply system 75 for supplying a processing gas is connected to the other end of the gas supply pipe 74.

On the other hand, two multi-pole ring magnets 25a and 25b are arranged around the upper portion 2a of the processing container 2 with the carry-in and out ports 23 interposed therebetween. The multipole ring magnets 25a and 25b are formed by attaching a plurality of anisotropic segment column magnets to a casing of a ring-shaped magnetic body, so that the directions of the adjacent plurality of segment column magnets are opposite to each other. It is arranged. As a result, magnetic force lines are formed between adjacent segment magnets, and a magnetic field is formed only in the periphery of the processing space between the upper and lower electrodes, and has a function of confining the plasma in the processing space.

Next, the cooling block 80 is demonstrated in detail. The cooling block 80 is formed of a base material 8 made of aluminum (Al), and as shown in FIG. 2, a curved flow path 81 for passing a coolant, for example, water, inside the base material 8. ) Is formed. A gas discharge hole 82 (between the flow path 81 and the flow path 81 in this example) is formed on the surface of the cooling block 80 to avoid the flow path 81. The gas discharge holes 71 formed in the electrode plate 7a and the gas discharge holes 82 formed in the cooling block 80 each have a gas discharge hole when the electrode plate 7a and the cooling block 80 overlap each other. The positions 71 and 82 coincide and overlap each other, and the processing gas is discharged from the gas discharge holes 71 and 82 into the processing space between the upper and lower electrodes. The coolant is introduced into the flow path 81 via the coolant inlet tube 83a, discharged from the coolant discharge tube 83b, and circulated through a temperature control device outside the plasma processing apparatus, whereby the upper electrode 7 The plasma is controlled at the set temperature, and the plasma generated above the wafer W is controlled in a state suitable for the process. The coolant introduction pipe 83a and the coolant discharge pipe 83b extend upward from the upper surface of the cooling block 80 as shown in Figs. 1 and 2 to form a flow path within the cylindrical upper portion 2a. Connected. In addition, in FIG. 1, the coolant introduction pipe 83a is hidden by the coolant discharge pipe 83b and is not seen. 3, the zinc oxide film (anticorrosive film) 94 mentioned later is formed in the whole inner peripheral surface of the said flow path 82. As shown in FIG.

The manufacturing method of this cooling block 80 is demonstrated concretely using FIG. 4 and FIG. First, the 1st base material (lower member) 8a and the 2nd base material (upper member) 8b which consist of the aluminum which processed the flow path formation recessed part 80a of the cooling liquid on one surface side are prepared (FIG. 4 (a). )]. Then, a coating liquid (slurry) obtained by dispersing zinc (Zn) powder in a solvent such as a solvent on the upper surface of the first base material 8a is applied with a gas spray or the like, and a solder material is applied to the upper surface of the second base material 8b. For example, the coating liquid (slurry) which disperse | distributed nickel (Ni) powder to the solvent is apply | coated (FIG. 4 (b)). Moreover, it is preferable to apply | coat 30 g or more zinc per 1m <2> in spray application. As shown in Fig. 4B, a Zn coating film 91 is formed on the surface of the first base material 8a, and a Ni coating film 92 is formed on the surface of the second base material 8b. Is formed.

Thereafter, the surface on which the coating film 91 of Zn is formed on the first base material 8a and the surface on which the coating film 92 of Ni is formed on the second base material 8b are brought into contact with each other to form a reduced pressure atmosphere containing oxygen, For example, it is carried in the heating furnace which exists in a pressure-reduced air atmosphere, and for example, as shown to Fig.5 (a), the 1st base material 8a side is supported by a support part, and the upper surface of the 2nd base material 8b is carried out. Heating while pressing. Thereby, zinc and nickel diffuse in aluminum at the joining surface, and the joining layer (diffusion joining layer) 93 which consists of Al-Zn-Ni is formed and diffusion bonding is achieved. Moreover, the recessed part 80a of the 1st base material 8a is covered with the 2nd base material 8b, and the flow path 81 of the cooling block 80 is formed. In this recessed portion 80a, a zinc oxide film 94 is formed of zinc and oxygen. In this example, the zinc oxide film 94 is specifically a composite oxide film of Zn-Ni-Al. That is, the zinc oxide film 94 is formed on the entire inner surface of the flow path 81.

Subsequently, as shown in FIG. 5C, the cooling block 80 is cut between the flow path 81 and the flow path 81 by using a cutting tool, for example, a drill 85, for example, a diameter of 0.5. Gas discharge holes 82 of 1 mm to 1 mm are formed.

Moreover, although the recessed part 80a is processed in the one surface side of the 1st base material 8a in this example, you may process the recessed part 80a in the one surface side of the 2nd base material 8b, or a 1st base material The recessed part 80a is processed in the position corresponding to each other in both surfaces of 8a and the 2nd base material 8b, and the flow path 81 is formed between the recessed parts 80a of both base materials 8a and 8b. It may be formed.

Next, an example of the operation of the plasma etching apparatus configured as described above will be described. First, the gate valve 24 is opened, the wafer W is loaded into the processing container 2 from the inlet / outlet 23, mounted on the support table 3, and the electrostatic chuck 34 from the DC power supply 35. After a predetermined voltage is applied to the electrode 34a of the electrode, the electrostatic chuck 34 is sucked and held, and the vacuum pump 22 exhausts the inside of the processing container 2 to a predetermined degree of vacuum through the exhaust port 21. .

Then, the processing gas, for example, fluorine (F), etc. from the processing gas supply system 75 reaches the space 73 of the shower head 6 via the gas supply pipe 74 and the gas inlet 72. It discharges to a process atmosphere through the gas discharge hole 82 of the cooling block 80, and the gas discharge hole 71 of the electrode plate 7a. Then, the gas pressure in the processing vessel 2 is set to, for example, 13 Pa to 1333 Pa (100 mTorr to 10 Torr), and in this state, a high frequency power of, for example, 100 MHz is supplied from the first high frequency power source 26 to the support table 3. Supply. This high frequency flows through the path of the support table 3, the processing space, the upper electrode 7, the cooling block 80, and the processing container 2, and a high frequency electric field is formed in the processing atmosphere.

In addition, from the second high frequency power source 27, for example, 3.2 MHz of high frequency power is supplied to control the ion energy of the plasma, and a high frequency is provided between the upper electrode 7 and the support table 3 which is the lower electrode. An electric field is formed. In addition, since the horizontal magnetic field is formed between the shower head 6 and the support table 3 by the dipole ring magnets 25a and 25b, an orthogonal electromagnetic field is formed in the processing space between the electrodes where the wafer W is present. Is formed, and a magnetron discharge is formed by the drift of the resulting electrons. The magnetron discharge causes the processing gas to be plasma, and the predetermined film formed on the surface of the wafer W is etched by the plasma.

The coolant, for example, water, is introduced into the flow path 81 of the cooling block 80 from the coolant liquid introduction pipe 83a, so that the lower surface of the electrode plate 7a passes through the cooling block 80, for example, at a set temperature. Temperature is adjusted so that it may be maintained uniformly at 60 degreeC, and in-plane uniformity of the electron density of the plasma above the wafer W is attained by this.

According to the embodiment described above, since aluminum is used as the base material 8 of the cooling block 80, the two base materials 8a and 8b made of aluminum are satisfied while satisfying the original functions required for the upper electrode 7. By interposing the zinc with each other, as shown in FIG. 5, diffusion bonding in which zinc is diffused in aluminum and formation of a zinc oxide film 94 on the inner circumferential surface of the flow path 81 through which the coolant passes are simultaneously performed. Therefore, as described above, there is no defect such as when surface treatment is performed before soldering or surface treatment after soldering, and even a complicated flow path can form a zinc oxide film 94 to every corner, furthermore, There is no concern. Furthermore, the soldering and joining are performed simultaneously, simplifying the manufacturing process.

In addition, the zinc oxide film 94 is sacrificing against the corrosive action of the cooling liquid and thus protects aluminum, which is the base materials 8a and 8b, from corrosion, thereby increasing the service life of the cooling block 80. For example, even if a film crack occurs in the zinc oxide film 94 and a pinhole is formed, zinc is corroded earlier than aluminum from the relationship of electronegativity, thereby suppressing corrosion of aluminum. Therefore, the replacement frequency of the cooling block 80 decreases, and maintenance work is reduced. In addition, since the zinc oxide film 94 has substantially the same electrical conductivity and thermal conductivity as aluminum of the base material 8, there is no fear of impairing the electrical and thermal functions of the cooling block 80.

In addition, in the above-mentioned embodiment, although the cooling block 80 is provided in the upper surface of the electrode plate 7a, it may be provided in the support table 3 side, for example, and may comprise a part of lower electrode.

(2nd embodiment)

The cooling block which concerns on 2nd Embodiment of this invention is the structure in which the whole inner surface of the flow path 81 formed in the inside of the base material 8 is covered with stainless steel (SUS).

The manufacturing method of this cooling block 90 is demonstrated concretely using FIG. 6 and FIG. First, as shown in Fig. 6, the lower plate 94a made of SUS is processed to form a groove, for example, in parallel to form a concave portion 80a for forming a flow path, and the groove and groove of the lower plate 94a are formed. In the convex portion 80b of the intersecting portion, a hole 95 larger than the diameter of the hole for gas discharge in the base material described later is formed. Moreover, the hole 95 larger than the diameter of the hole for gas discharge in the base material mentioned later is formed in the surface of the flat upper plate 94b which consists of SUS. In addition, the hole 95 formed in the lower plate 94a and the hole 95 formed in the upper plate 94b respectively have holes 95 when the lower plate 94a and the upper plate 94b overlap. ) Are positioned to overlap and overlap. In addition, in the lower plate 94a, as shown in FIG. 2, the whole is circular, and in order to form the curved recessed part, it can process by using several plates, respectively, and can manufacture them by welding these plates. . 6 shows a part thereof. Subsequently, the lower surfaces of the lower plate 94a and the upper plate 94b are immersed in a crucible in which aluminum is melted, cooled and solidified, and then taken out from the crucible. This achieves diffusion bonding of SUS phase-Al in which SUS diffuses into aluminum in the contact surface between SUS and Al, and the base materials 8a and 8b made of aluminum are respectively formed on the lower surfaces of the lower plate 94a and the upper plate 94b. ) Is formed (Fig. 7 (a)). In addition, the holes 95 formed in the lower plate 94a and the upper plate 94b are filled with Al.

Thereafter, the lower plate 94a and the upper plate 94b are brought into contact with each other, for example, carried into a heating furnace in a reduced pressure air atmosphere, and as shown in FIG. 7B, for example, the lower plate 94a. ) Side is supported by the supporting portion, and is heated while pressing the upper surface of the upper plate 94b. Thereby, the bonding layer (diffusion bonding layer) 96 of SUS is formed in the joining surface of the lower plate 94a and the upper plate 94b, and diffusion bonding is achieved. Moreover, the recessed part 80a of the lower plate 94a is covered with the upper plate 94b, and the flow path 81 of the cooling block 90 is formed. Moreover, the bonding layer (diffusion bonding layer) 97 of Al in the bonding surface of Al filled in the hole 95 of the lower plate 94a, and Al filled in the hole 95 of the upper plate 94b is Is achieved. Thereafter, the cooling block 90 is obtained by cooling (FIG. 7C). In addition, the surface of Al is exposed in the hole 95 of the plates 94a and 94b made of SUS, and the gas discharge hole 82 is formed in the next step on this exposed surface.

That is, as shown in FIG. 7D, the cooling block 90 is exposed to the holes 95 of the plates 94a and 94b by using a drill 85 having a diameter smaller than that of the holes 95. The gas discharge hole 82 is formed by cutting Al which exists.

In addition, in this example, although the recessed part 80a is formed in the one surface side of the lower plate 94a, the recessed part 80a may be formed in the one surface side of the upper plate 94b, or the lower plate 94a. ) And recesses 80a are formed at positions corresponding to each other on both surfaces of the upper plate 94b and the upper plate 94b so as to form a flow path 81 between the recesses 80a of both plates 94a and 94b. Also good.

In the cooling block 90 described above, anodization may be performed on the shell of the base materials 8a and 8b made of aluminum.

The cooling block 90 obtained in this way can also be applied to the plasma processing apparatus shown in FIG.

According to the above-mentioned embodiment, since the flow path 81 formed in the base material which consists of aluminum is formed of SUS, the original function calculated | required by an electrode is satisfied. That is, since it is made of aluminum other than the flow path 81, even if there is SUS with high resistivity and thermal conductivity inside, the outer skin of aluminum becomes a path of high frequency and heat, and corrosion by the coolant can be prevented by SUS, The service life of the cooling block 90 is long.

In addition, according to the above-described embodiment, since the main surface of the cut gas discharge hole 82 is covered with Al, there is no fear that SUS will be corroded by the processing gas when the processing gas is discharged from the gas discharge hole 82. Therefore, the service life of the cooling block 90 can be extended also from this.

Moreover, as a board | substrate in this invention, it is not limited to a wafer like embodiment mentioned above, The glass substrate for flat panels used for a liquid crystal display, a plasma display, etc., a ceramic substrate, etc. may be sufficient.

EXAMPLE

Next, the experiment performed to confirm the effect of this invention is described.

(Example 1)

The test block corresponding to the cooling block 80 was manufactured by the same method (FIG. 4) as described in 1st Embodiment. The coating amount of zinc in the surface of the 1st base material 8a is 30g per 1m <2>. Moreover, the solder material containing 80 weight% or more of Ni was apply | coated to the surface of the 2nd base material 8b. This cooling block is called Example 1.

(Example 2)

A cooling block was produced in the same manner as in Example 1 except that the coating amount of zinc was 60 g per 1 m 2. This cooling block is referred to as Example 2.

(Comparative Example)

A cooling block was produced in the same manner as in Example 1 except that spray coating of zinc was not performed. This cooling block is called a comparative example.

(Test sequence, conditions and results)

In the circulation path including the flow path formed in the cooling block of Example 1, Example 2, and the comparative example, the corrosion promoting liquid of 5000 ml pH 6.4-6.8 (measured value 6.6) was circulated. The components contained in 5000 ml are 10 ppm copper ions, 100 ppm chlorine ions, 100 ppm sulfate ions and 100 ppm hydrogen carbonate ions. And every week, the corrosion accelerator circulating in the flow passage was replaced with a new one.

At each timing in which the corrosion promoting liquid was circulated for one week, two weeks, or 20 weeks, the portions in which the flow paths of the cooling blocks of Examples 1, 2 and Comparative Example were formed were cut out by a thickness of about 25 mm and soldered thereto. It cut | disconnected in the part and observed the corrosion state of the inner surface. The result is shown in FIG. In FIG. 8, the vertical axis | shaft shows the depth (mm) of a corrosion hole, and the horizontal axis shows the period which circulated the corrosion promoting liquid.

As shown in FIG. 8, it can be seen that in Examples 1 and 2, the progress of corrosion is slower than in Comparative Examples. That is, in Example 1, Example 2, and a comparative example, the time required for reaching the depth of a corrosion hole to 0.48 mm is 11 weeks in Example 1, 20 weeks in Example 2, and 8.5 weeks in Comparative Example. From this, it can be seen that Example 1 is about 1.3 times longer than the comparative example, and Example 2 is about 2.4 times longer than the comparative example. This is because corrosion by the corrosion promoting liquid is sacrificed in the zinc oxide film 94. Moreover, since the zinc oxide film 94 has a lower potential than aluminum, the progress of corrosion is slower than aluminum. From this, it can be understood that it is effective to form the zinc oxide film 94 on the entire inner surface of the flow path 81 of the cooling block 80. In addition, as described above, since the service life of the second embodiment is longer than that of the first embodiment, the depth of the corrosion hole can be further suppressed by increasing the coating amount of zinc on the surface of the first base material 8a, It turns out that it is desirable to set it as 30 g or more per 1 m <2>.

According to the present invention, since aluminum is used as the base material, it satisfies the original function required of the electrode, and the diffusion bonding in which zinc is diffused into aluminum by interposing two base materials made of aluminum through zinc, Since the formation of the zinc oxide film on the inner circumferential surface of the flow passage flowing therethrough is performed at the same time, as described above, there is no defect such as when surface treatment is performed before soldering or surface treatment after soldering. Zinc oxide films can be formed to every corner, and there is no fear of film cracking. Furthermore, the soldering and joining are performed simultaneously, simplifying the manufacturing process.

In addition, the zinc oxide film is sacrificed against the corrosive action of the cooling liquid to protect the base metal from corrosion, thereby increasing the service life of the cooling block. Therefore, the replacement frequency of a cooling block becomes small, and maintenance work is reduced. Further, since the zinc oxide film has almost the same electrical conductivity and thermal conductivity as aluminum of the base metal, there is no fear of impairing the electrical and thermal functions of the cooling block.

Moreover, since another flow path formed in the base material made of aluminum is formed of SUS, another invention satisfies the original function required for the electrode and can prevent corrosion by the cooling liquid in the SUS. Long lifespan

Claims (7)

In the cooling block which comprises the electrode for generating the plasma used for a plasma process, and has the flow path of a cooling liquid inside, The zinc is formed by joining each of the first base material and the second base material each made of aluminum and at least one of which is formed with a recess for forming a flow path of the cooling liquid under a heating atmosphere containing oxygen in a state where zinc is interposed therebetween. An anticorrosive layer composed of a diffusion bonding layer and a zinc oxide film diffused in aluminum is formed simultaneously. Cooling block. The method of claim 1, The amount of zinc in the zinc oxide film is 30 g or more per m 2 Cooling block. The method according to claim 1 or 2, Between the first base material and the second base material, a solder material selected from nickel, silicon, copper, boron, phosphorus, chromium, iron and carbon is interposed. Cooling block. The method according to claim 1 or 2, In order to supply the processing gas for plasma generation to a processing atmosphere, many gas supply holes penetrating in the thickness direction are formed, and it is comprised as an upper electrode which opposes the lower electrode in which a to-be-processed object is mounted, It is characterized by the above-mentioned. Cooling block. In the cooling block which comprises the electrode for generating the plasma used for a plasma process, and has the flow path of a cooling liquid inside, A plate made of stainless steel is bonded to the surface of the base material each made of aluminum, and the first member and the second member, each of which is formed with a recess for forming a flow path of a cooling liquid on at least one of them, are joined in a state where the plates face each other. The joining portion of the plate of the first member and the plate of the second member is formed with a diffusion bonding layer of stainless steel, The joining portion of the base material and the plate made of aluminum is characterized in that the diffusion bonding layer of stainless steel and aluminum is formed Cooling block. The method of claim 5, wherein In order to supply the processing gas for plasma generation to a processing atmosphere, a plurality of gas supply holes penetrating in the thickness direction are formed, and are configured as upper electrodes facing the lower electrodes on which the target object is to be mounted, The inner circumferential portion of the gas supply hole formed in the plate made of stainless steel is covered with aluminum of the base material. Cooling block. The airtight processing container, the mounting table which is provided in the inside of the said processing container, and combines the electrode for holding the board | substrate to be plasma-processed, is provided in the inside of the said processing container so as to oppose the said mounting table, Claim 1 or The process gas is plasma-formed by forming a high frequency electric field between an electrode including the cooling block according to claim 5, a gas supply unit for introducing a processing gas into the processing container, and the mounting table and the electrode opposite to the mounting table. Plasma generating means for Plasma processing apparatus.

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