JP3126561B2 - Vacuum processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal bonding structure and a method of manufacturing the same, and more particularly to a seal bonding structure used in a processing apparatus for low-temperature and low-pressure processing and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, plasma processing is generally performed in a temperature atmosphere near room temperature.
To meet the demand for higher integration, it is desired to ensure a high selectivity and anisotropy, for example, during plasma etching. For this reason, recently, a so-called low-temperature plasma processing apparatus has been developed in which an object to be processed is cooled to a low-temperature atmosphere, for example, −150 ° C. using a refrigerant, for example, liquid nitrogen, and plasma processing is performed under reduced pressure in that state.

According to such a low-temperature plasma processing apparatus, when etching a polysilicon or a silicon oxide film, for example, the selectivity with respect to the underlying material can be greatly improved as compared with the conventional method. Since a sufficient property can be ensured, it becomes possible to carry out etching in a forward tapered shape or a vertical shape without undercut.

However, in a low-temperature plasma processing apparatus,
Since the processing itself is performed at a low temperature, it is very difficult to maintain the airtightness inside the processing chamber. Therefore,
When the members constituting the processing apparatus are sealed and joined, a sealing member such as an O-ring made of fluorine rubber or a Teflon ring having a built-in spring is interposed.
Attempts have been made to secure sealing properties by fastening with a tightening force per unit circumferential length as strong as 0 to 100 kgf / cm.

[0005] More recently, corrosion-resistant highly elastic materials,
For example, a material having high ductility or malleability, such as indium (In), gold (Au), silver (Ag), zinc (Zn), is used for a high-grade stainless steel material such as SUS316 or a nickel-cobalt alloy such as Inconel or Hastelloy. ),
Sealing technology that uses a sealing material coated with a metal material such as copper (Cu) or a polymer material such as Teflon or high-molecular polyethylene to maintain the desired elasticity with a small clamping force per unit circumference even at low temperatures. Is being developed.

[0006]

However, in order to obtain a good seal, if the surface to be sealed of the aluminum component member against which the seal member is pressed is rough, a leak is generated from the uneven surface. The surface of the member to be sealed must also be kept smooth. Therefore, it is conceivable that the surface to be sealed of the aluminum component is polished and the seal joining is performed using the above-described sealing member. However, electrical insulation is required in most of the sealing portions of the processing chamber. Therefore, in such an insulating portion, the polished aluminum surface cannot be used as it is as the surface to be sealed. Also, since the surface hardness of aluminum is low, when a hard foreign substance, for example, a deposit product, is caught between the polished surface to be sealed and the sealing member, the polished surface to be sealed becomes rough and irregularities are formed. And leaks therefrom, which has been a problem.

[0007] In order to meet the demand for electrical insulation at the sealing joint, it has been attempted to anodize the surface to be sealed of the aluminum component by forming an anodized film thereon to achieve insulation. Has a problem because it is rough and has irregularities and is porous, and leakage cannot be avoided.

The present invention has been made in view of the problems of the conventional seal bonding structure in the low-temperature plasma processing apparatus as described above, and an object of the present invention is to achieve a demand for electrical insulation. Further, it is an object of the present invention to provide a new and improved leak-joined structure having a sufficiently high surface hardness, excellent gas corrosion resistance, and less likely to leak, and a method for manufacturing the surface to be sealed.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems
According to the present invention, the object to be processed is processed under reduced pressure.
Vacuum processing equipment, which constitutes a part of the processing equipment.
Luminium members are separated by elastic sealing members.
Vacuum processing equipment is provided which is pressed and sealed
You. And this vacuum processing apparatus is described in claim 1.
As shown in the figure, the aluminum member in contact with the sealing member
Alumite film is formed on the surface by anodizing.
The alumite film is polished after the sealing process.
It is characterized by being. With such a configuration
If the alumite film by anodizing
Electrical insulation performance, corrosion resistance and sufficient hardness
Alumite on the surface to be sealed of the aluminum member
The coating has a smooth surface that is polished after sealing
This improves the adhesion of the sealing member to the coating film,
With a smaller clamping force per unit circumference than the conventional one
Also, high sealing performance can be secured.

Further , as described in claim 2, after polishing,
The surface of the alumite film has an average roughness of 0.1a to 0.
5a is preferred. It should be noted that the flat
The average roughness refers to the center line average roughness (Ra or a).
Absolute value of the roughness curve with respect to the center line
The area consisting of the center line is expressed in micrometers.
is there.

Further , as described in claim 3, the algorism
Polishing of the mite film should be performed within the thickness of the growth layer.
Preferably. Polishing beyond the growth layer to the permeation layer
Then, in some cases, the underlying aluminum layer is exposed
This is because it can happen.

Further, as set forth in claim 4, the a
The luminium member constitutes a mounting table for mounting the object to be processed.
If it is a member to be processed,
Minimize the leakage of heat transfer gas supplied to the surface.
And, as claimed in claim 5,
The vacuum processing device is configured to reduce the temperature of the object under reduced pressure and low temperature.
If it is a low-temperature processing device for processing at
It is possible to efficiently cool the object placed on the
is there.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a plasma bonding apparatus according to an embodiment of the present invention; FIG.

An etching apparatus 1 shown in FIG. 1 has a processing vessel 2 formed of a cylindrical or rectangular shape made of a conductive material, for example, aluminum or the like. An insulating material such as ceramic is provided at the bottom of the processing vessel 2. A substantially columnar mounting table 4 for mounting an object to be processed, for example, a semiconductor wafer W, is accommodated via the plate 3. The mounting table 4 is configured by assembling a plurality of members, which will be described later, formed of aluminum or the like with bolts or the like. More specifically, the mounting table 4 is mainly constituted by a susceptor support 5 formed in a columnar shape of aluminum or the like, and a susceptor 7 made of aluminum or the like which is detachably provided by bolts 6 thereon. ing.

The susceptor support 5 is provided with a cooling means, for example, a cooling jacket 8, into which a refrigerant such as liquid nitrogen is introduced via a refrigerant introduction pipe 9 and circulates in the jacket. And the refrigerant discharge pipe 10
The gas generated by evaporation of the liquid nitrogen is discharged outside the container. Therefore, the cooling heat of the liquid nitrogen at −196 ° C. is supplied from the cooling jacket 8 through the susceptor 7 to the semiconductor wafer W.
, And the processing surface of the semiconductor wafer W can be cooled to a desired temperature.

The susceptor 7 is formed in a disk shape having a central upper end in a protruding shape, and an electrostatic chuck 11 is formed at the center of the wafer mounting portion with an area substantially equal to the wafer area. The electrostatic chuck 11 is formed, for example, by sandwiching a conductive film 12 such as a copper foil between two polymer polyimide films in an insulated state. The conductive film 12 is connected to a variable DC high-voltage power supply 13 by a lead wire. ing.
Therefore, by applying a high voltage to the conductive film 12, the semiconductor wafer W can be suction-held on the upper surface of the electrostatic chuck 12 by Coulomb force.

Heat transfer gas such as He is supplied to the susceptor support 5 and the susceptor 7 through the susceptor support 5 and the susceptor 7 to the back surface of the semiconductor wafer W, their joints, joints between members constituting the susceptor 7, and the like. Gas passage 14 is formed. In addition, on the peripheral edge of the upper end of the susceptor 7,
An annular focus ring 1 surrounding the semiconductor wafer W
5 are arranged. The focus ring 15 is made of an insulating material that does not attract the reactive ions, and acts so that the reactive ions are effectively incident only on the inner semiconductor wafer W.

Further, a high-frequency power supply 17 is connected to the susceptor 7 via a matching capacitor 16, and a high-frequency power of, for example, 13.56 MHz is applied to the susceptor 7 during processing so that the susceptor 7 functions as a lower electrode. Is possible. Above the susceptor 7
A grounded upper electrode 18 is provided at a distance of about 15 to 20 mm from this, and a processing gas, for example, an etching gas such as CF ₄ is supplied to the upper electrode 18 via a gas supply pipe 19. The etching gas is uniformly blown into the processing space below through a large number of small holes 20 formed on the electrode surface of the upper electrode 18.

An exhaust pipe 21 is connected to the lower side wall of the processing container 2 so that the atmosphere in the processing container 2 can be exhausted by an exhaust pump (not shown). A gate valve (not shown) is provided, and the semiconductor wafer W is connected through the gate valve.
It is configured to carry in and carry out.

Further, below the susceptor between the electrostatic chuck 11 and the cooling jacket 8, there is provided a temperature control heater 23 housed in a heater fixing base 22. By adjusting the supplied electric power, the conduction of the cold heat from the cooling jacket 8 is controlled so that the temperature of the surface to be processed of the semiconductor wafer W can be adjusted.

In each of the members constituting the low-temperature plasma processing apparatus 1 configured as described above, a seal member 25 to be described later is interposed at a site where an airtight seal is required. The airtightness is maintained. Specifically, a pair of seal members 25A and 25B are interposed in a ring shape at a seal joint 26 between the upper surface of the susceptor support base 5, the lower surface of the susceptor 7, and the lower surface of the heater fixing base 22, and the lower surface of the susceptor 7 and the heater A seal member 25C is interposed in a seal joint 27 between the upper surface of the fixed base 22 and the seal joint 2 between the upper surface of the susceptor 7 and the lower surface of the electrostatic chuck 11.
8, a pair of seal members 25D and 25E are interposed in a ring shape.

Each seal member 25 is, as shown in FIG.
It has a seal base material 29 formed in a bendable ring shape having a C-shaped cross section, and a coating film 30 is formed on the surface thereof. As the sealing base material 29, a corrosive gas is used as the processing gas, and therefore, a highly elastic material having corrosion resistance,
For example, high-grade stainless steel such as SUS316 or nickel-cobalt alloy such as Inconel or Hastelloy is used. Other than these materials, any material may be used as long as it has a high elastic modulus and a high yield point in order to guarantee a high elastic modulus even at a low temperature.

As the coating film 30, a material having high ductility or malleability, for example, indium (I
n), gold (Au), silver (Ag), zinc (Zn), copper (C
It is possible to use a metal material such as u) or a polymer material such as Teflon or high-molecular polyethylene. By forming such a coating film 30, the conformability to the member surface is improved, and the sealing property is not deteriorated even at an extremely low temperature of about -150 ° C. Further, the coating film need only be applied to at least a portion that comes into contact with the surface of the member at the time of interposition. Therefore, in the illustrated example, the coating film is applied only to the outer surface of the sealing base material 29, and is applied to the inner surface. Absent.

FIG. 3 is an enlarged view showing a state in which each seal member 25 is interposed. In the illustrated example, as an example, upper and lower members, for example, the upper surface of the heater fixing base 22 and the lower surface of the susceptor 7, The seal member 25C is interposed therebetween, and a small gap S having a width of about 0.1 mm is formed between these members in order to appropriately convect the heat transfer gas. The seal member 25C is housed in, for example, a lower member, that is, in the illustrated example, a ring-shaped seal groove 31 having a rectangular cross section formed on the upper surface of the heater fixing base 22, and has upper and lower ends. The groove size or the size of the seal member is set so as to be in contact with both members.

Here, the sealing member 25 configured as described above is airtightly contacted and joined to the heater fixing base 22 and the susceptor 7 at the seal joining surfaces 32 and 33. In order to complete the seal joint structure with high airtightness with a tightening force per unit circumferential length, the seal joint surfaces 32 and 33 need to be smooth. According to the knowledge of the present inventor, the average roughness is By keeping the pressure at 0.1a to 0.5a, preferably about 0.2a, it is possible to maintain the seal joint surface in a leaktight atmosphere suitable for technical requirements. At the same time, the sealing surfaces 32, 33 generally need to be electrically insulated.

In order to meet such technical requirements, the present inventors processed the seal joint surface of the constituent material of the low-temperature plasma processing apparatus by a method as shown in FIG. Excellent effects could be obtained. First, the sealing surface of an aluminum member as shown in FIG. 4 (a) is anodized by subjecting it to an anodizing film treatment by a known electrolytic technique, whereby it is possible to impart insulation, gas corrosion resistance and hardness. It is. As the electrolytic solution, for example, sulfuric acid, oxalic acid, chromic acid, and the like can be used.However, in consideration of the occurrence of cracks and the hardness of the film, preferably sulfuric acid or oxalic acid, more preferably sulfuric acid, is used. It is preferred to form alumite. Note that the surface of the aluminum material before the anodic oxide film treatment has a certain degree, for example, 6.3a to 6.3a.
It is preferable to grind to an average surface roughness of 12.6a. In other words, if the surface before the treatment is too rough, extra work is required for the polishing work described later, and the leak is likely to occur. Since it becomes useless, it is considered that it is preferable from the viewpoint of processing efficiency to perform the grinding process up to the above average surface roughness.

As shown in FIG. 4B, the sulfuric acid hard alumite film thus formed generally comprises a permeation layer formed inside the aluminum material and a growth layer formed outside the aluminum material. For example, when a film of 50 μm is formed, the penetration layer and the growth layer are almost 25 μm.
m. In addition, the sulfuric acid hard alumite film formed in a known manner is formed from a porous layer in which small pores are regularly opened and a non-porous layer under the porous layer, but if the porous layer is left as it is, the small pores are formed. It is necessary to remove the porous layer because there is a possibility of corrosion or leakage from the part.
Therefore, according to the present invention, the sealing treatment for boehmite the oxide film surface with the steam is performed. However, Table 1
As shown in the figure, the surface roughness after the steam sealing treatment is 1.0
Therefore, the surface needs to be smoothed by polishing.

Therefore, according to the present invention, the surface of 50 μm is polished by about 20 μm as shown in FIG. Work until it reaches 0.5a, preferably about 0.2a. In addition, when polishing is performed to the permeation layer beyond the growth layer, the underlying aluminum layer may need to be exposed in some cases. Therefore, it is preferable to perform the polishing within a range not exceeding the thickness of the growth layer.

Next, when the test pieces (1) and (2) shown in FIGS. 5 and 6 were subjected to (a) 50 micron sulfuric acid hard alumite (steam sealing treatment), the surface of the alumite was removed.
To what extent the roughness is rough, (b) whether the treated surface after the above treatment can be polished to 0.1a, 0.2a, and 0.4a is possible; and for comparison, (c) TiN treatment is performed to determine the roughness of the treated surface. Table 1 shows the results of a measurement and a test of how the surface after polishing with TiN was polished. The test piece (1) was manually polished with diamond powder, and the test piece (2) was polished mechanically with diamond powder. In the figure, the hatched portion indicates a polished portion, and an arrow region of the hatched portion indicates a surface roughness measurement region. Further, in Table 1,
A, B, and C are measurement results of the test piece (2), and D, F,
H is the measurement result at the location X of the test piece (1),
E, G, and I are the measurement results at the location Y of the test piece (1), and J, K, L, and M are the measurement results at the location X of the test piece (1).

[0030]

[Table 1]

As a result of the measurement, as is clear from A to I in Table 1, before performing 50 μm of sulfuric acid hard alumite (steam sealing treatment), the surface was finished smooth and then anodized. In the case of the sample, the surface is considerably roughened, so it is meaningless to perform the surface polishing more than necessary before the alumite treatment. As described above, for example, the average surface roughness of 6.3a to 12.6a is used. It is enough to grind up to.

As is clear from Tables A to I, the treated surface is polished with a polishing agent such as diamond powder after 50 μm of sulfuric acid hard alumite (steam sealing treatment) to obtain an average roughness of 0.1a to 0%. It was found that finishing was possible in the range of 0.5a. Thus corrosion resistance, insulation,
It has been found that a high sealing effect can be obtained by processing an alumite surface having excellent hardness to an average roughness of 0.1a to 0.5a, preferably about 0.2a.

As a comparative example, as shown in J to M in Table 1, when the substrate coated with Kanigen was subjected to TiN treatment, the surface was considerably roughened, and the underlying Kanigen plating was exposed. It was found that they could not be treated and could not be used as seal joining members for low-temperature treatment equipment.

As described above, the seal member 25 is attached to the seal joint surfaces 31 and 32 formed according to the present invention.
For example, by tightening with a suitable number of bolts at a tightening force per unit circumference, for example, 8 kgf / cm to 10 kgf / cm, for example, 1 × 10 ⁻⁶ Atm · cc / sec.
It is possible to obtain a leak tight seal joint structure of c or less. In the illustrated example, the case where the seal joint structure is provided only at a typical joint portion for the sake of simplicity has been described. However, the seal joint structure is exposed to a low temperature, and the sealability, gas corrosion resistance, hardness, It is possible to adopt a seal joint structure configured based on the present invention for a plurality of parts that require a proper insulating property.

Next, the overall operation of the low-temperature processing apparatus configured as described above will be described. First, a semiconductor wafer W, which is an object to be processed, is placed on a susceptor 7 in a processing vessel 2 which is reduced to a predetermined pressure, for example, about 1 × 10 ⁻⁴ to several Torr from a load lock chamber (not shown). This is sucked and held by the electrostatic chuck 11. Next, plasma is generated by applying a high frequency between the upper electrode 18 and the susceptor 7 constituting the lower electrode, and at the same time, a process gas is flowed from the upper electrode 18 into the processing space to perform an etching process.

The heat generated by the plasma causes the semiconductor wafer W
Is heated to a temperature higher than a predetermined set temperature, so that a cooling medium,
For example, liquid nitrogen is allowed to flow, and this portion is, for example, -196.
In this case, the temperature is maintained at a temperature of 0 ° C., and the heat of the future is transferred to the semiconductor wafer W via the susceptor 7 to maintain the processing surface in a desired low temperature state. Further, the transfer of cold heat can be controlled by adjusting the amount of heat generated by the temperature control heater 23.

Here, a helium gas for heat transfer is flowed through the gaps between the members in order to promote the heat transfer of cold heat, and some of the gaps between the members are communicated with the atmosphere. Therefore, there is a possibility that helium gas or atmospheric components may leak into the processing container 2 under reduced pressure through the gap between the members. However, according to the present invention, since the gasket resistance, electrical insulation, hardness, seal joint structure excellent in sealability is adopted in each part, even in the case of performing low-temperature treatment, leak tight Environment is preserved.

After completion of the etching process, the residual gas in the processing chamber is exhausted through the exhaust pipe 21, the semiconductor wafer is heated to an appropriate temperature, and the adjacent load lock chamber is opened via a gate valve (not shown). Is carried out to
A series of processing ends.

In the above embodiment, the case where the present invention is applied to a low-temperature plasma etching apparatus has been described. However, the present invention is not limited to such an embodiment, and the object to be processed is processed under low-temperature and reduced-pressure conditions. Equipment such as semiconductor wafers and L
The present invention can also be applied to a prober device for inspecting electrical characteristics of a CD or the like at a low temperature, an electron microscope for observing a sample under a low-temperature vacuum, and the like. In the above embodiment,
Is the case where a low-temperature processing device is used as a vacuum processing device.
Although the present invention has been described by way of example, the present invention is not limited thereto.
Needless to say, it is not limited to the example.

[0040]

As described above, according to the seal joining structure and the method of manufacturing the surface to be sealed according to the present invention,
Since the sealing member is pressed against the surface to be sealed having excellent electrical insulation properties, gas corrosion resistance, hardness, smooth surface and excellent sealing properties, a leaktight environment can be obtained. Further, the tightening force per unit circumferential length can be reduced as compared with the conventional low-temperature processing apparatus, so that the configuration of the apparatus can be simplified and the maintainability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram showing an embodiment of a processing apparatus according to the present invention.

FIG. 2 is a perspective view showing a seal member that can be employed in the present invention.

FIG. 3 is a cross-sectional view showing a seal joint structure according to the present invention.

FIG. 4 is an explanatory view showing a manufacturing process of a sealed surface structure manufactured according to the present invention.

FIG. 5 is an explanatory view showing a sample for measuring the effect of the present invention.

FIG. 6 is an explanatory diagram showing a sample for measuring the effect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching apparatus 2 Processing container 4 Mounting table 25 Seal member 26, 27, 28 Seal joint

Claims (5)

(57) [Claims] 1. A vacuum processing apparatus for processing an object to be processed under reduced pressure, wherein an aluminum member forming a part of the processing apparatus is sealed by being pressed via an elastic sealing member. In the vacuum processing apparatus described above, an alumite film is formed on the surface to be sealed of the aluminum member in contact with the sealing member by anodizing treatment, and the alumite film is polished after sealing treatment. , Vacuum processing equipment. 2. The surface of the alumite film after polishing is as follows:
Characterized by an average roughness of 0.1a to 0.5a,
The vacuum processing apparatus according to claim 1. 3. The vacuum processing apparatus according to claim 1, wherein the polishing of the alumite film is performed within a range not exceeding the thickness of the growth layer. 4. The method according to claim 1, wherein the aluminum member is a member constituting a mounting table on which the object to be processed is mounted.
The vacuum processing apparatus according to claim 1. Wherein said vacuum processing apparatus is characterized in that the a low-temperature processing apparatus for processing a workpiece at reduced pressure and low temperature state, according to any one of claims 1 to 4
Vacuum processing equipment.