JP2007157923A - Processing chamber and its protective material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective material used for protecting the inner wall of a easily handled, and easily maintained lightweight vacuum reaction tank, and to provide a processing chamber equipped with the above protective material. <P>SOLUTION: The protective material is a cylindrical electric insulating liner prescribed in thickness for keeping high in heat-resistant properties, has a low water-absorption rate, and is formed of polyimide film of low metal ion concentration to protect the inner wall of a processing chamber. The processing chamber is a chamber equipped with the above electric insulating liner which is provided near its wall to protect it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a process chamber of a semiconductor manufacturing apparatus having various vacuum reaction vessels, for example, and relates to, for example, thermal chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), plasma-assisted (plasma- The present invention relates to a process chamber used for various different processes such as assisted etching and deposition topography modification by sputtering, and a protective material thereof. Generally, the protective material is called a chamber wall or a liner, and is used for the purpose of protecting the chamber wall surface.

  The semiconductor industry is subject to deposition topography modification by sputtering, thermal chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), plasma-assisted etching, and sputtering. Rely on high throughput single substrate (single wafer) processing reactors that can be used for a variety of different processes.

  Although this treatment reactor requires manual cleaning, in order to avoid the decrease in productivity caused by cleaning the inside of the reactor, it can be cleaned without using the plasma etching technique. It would be desirable to have something like a processing reactor.

The following cases are exemplified as the reason why the inside of the reactor needs to be cleaned. For example, in a dry etching apparatus, in order to process a silicon oxide film, a polysilicon film, or an aluminum metal film into a predetermined pattern, for a semiconductor wafer in which an organic resin resist is formed in a predetermined pattern on the surface of the film, Plasma discharge is performed while flowing a reactive gas such as CF ₄ , CHF ₃ , Cl ₂ + O ₂ , Cl ₂ + BCl ₃ , and the film is etched. However, since etching and deposition are competitive reactions, depending on processing conditions, a reaction product of an etching gas, a film to be etched, and an organic resist adheres to the inside of the reactor (for example, a vacuum reaction tank). Therefore, it is necessary to periodically disassemble and clean the vacuum reaction tank.

  However, for example, since the vacuum reaction tank itself cannot be easily removed, a cylindrical protective member for preventing the above-mentioned reaction product from adhering to the inner wall of the vacuum reaction tank, generally a member called a chamber wall or a liner is attached. ing. The cylindrical protective member is generally made of ceramic, anodized, or quartz.

  Patent Document 1 describes a CVD chamber having a wall surface made of quartz. Patent Document 2 describes a method of limiting residue accumulation by lining the exhaust space portion of the process chamber and the exhaust manifold with ceramic. Patent Document 3 describes a sputter etching process as a method for cleaning the surface of an electrostatic ceramic chuck.

JP 2001-522138 A (Claim 1, paragraph number [0004]) Japanese Patent Laid-Open No. 9-251992 (page 4, paragraph number [0015]) Japanese Patent Laid-Open No. 11-3878 (page 4, paragraph number [0011])

By the way, when cleaning and maintenance of the cylindrical protective member described above, it is usually necessary to periodically remove the protective member from the reactor and perform a cleaning process and a maintenance process (repair, etc.), but remove the protective member from the reactor. That was a very cumbersome task.

  In addition, since the cleaning / maintenance processing is generally outsourced to an outside contractor, there is a problem that the processing takes a long time. Furthermore, with the recent increase in wafer diameter, the cylindrical protective member itself becomes larger and heavier, and there is a problem that much labor is required for handling.

  Further, Patent Document 1 describes that it is not easy to remove the object attached to the wall surface of the quartz chamber by etching, and that wet cleaning or replacement of the quartz chamber is necessary (paragraph number [0004]). .

  Furthermore, the sputter etching process described in the above-mentioned Patent Document 3 cannot be completely cleaned, and the trouble of removing the member from the process chamber in the maintenance process is the same, and improvement has been desired.

  The present invention has been made in view of the above circumstances, and its object is to provide a process chamber that is easy to maintain and provided with a protective material that protects the inner wall surface of the vacuum reaction tank, and a protective material therefor. For the purpose.

  As a result of intensive studies to achieve the above object, the present inventors have made an organic resin a cylindrical member that protects the inner wall surface of a cylindrical reaction vessel (also generally referred to as a reaction chamber or a process chamber). Alternatively, it has been found that providing an organic resin on a cylindrical member does not cause the above problem, and that maintenance can be performed easily and reliably, and the present invention has been completed.

That is, the present invention
A process chamber in which a plasma is generated,
An electrically insulating liner for protecting the process chamber wall surface is provided in the vicinity of the process chamber wall.

  With this configuration, the operation and effect are as follows. That is, for example, a wafer is inserted and installed inside the process chamber, and plasma is generated under a predetermined condition to cause various reactions (for example, thin film formation, etching, sputtering, etc.). The process chamber wall surface is provided with an electrically insulating liner.

  With this configuration, cleaning or maintenance can be performed easily and reliably without causing the above problems.

  As a preferred embodiment of the present invention, the liner is preferably composed of a polyimide film. Further, it is preferable that the liner has a cylindrical shape and has a self-supporting property. A polyimide film is preferable because it is electrically insulating and can be easily formed into a cylindrical shape by a manufacturing method to ensure self-supporting property. If the inner surface of the process chamber is cylindrical, it can be easily installed and removed from the inner wall surface of the process chamber by forming a cylindrical polyimide form suitable for the shape and dimension so as to be self-supporting.

  Further, it is preferable that the thickness of the liner is 25 μm or more and the plasma electric barrier thickness is sufficient to protect the process chamber wall surface. In order to exhibit the plasma electric barrier function, it is necessary to set the thickness of the liner. When the liner is formed of a polyimide film, the thickness is preferably 25 μm or more. More preferably, the thickness of the polyimide film is in the range of 50 μm or more and 150 μm or less, and the glass transition point is more preferably 250 ° C. or more. This is because, for example, in the case of a process chamber used in a PVD apparatus (apparatus used for physical vapor deposition), the reaction temperature is as high as about 400 ° C., and thus heat resistance of about 200 ° C. is required.

  Moreover, it is preferable that the water absorption rate of a polyimide film is 3% or less. If the water absorption rate exceeds 3%, it causes contamination of the wafer, which is not preferable. Further, the water absorption is more preferably 2% or less, and particularly preferably 1% or less. The lower the water absorption, the lower the wafer contamination.

The volume resistivity of the polyimide film is preferably 10 ¹⁶ Ω · cm or higher. When the volume resistivity is less than 10 ¹⁶ Ω · cm, the plasma electric barrier function cannot be sufficiently exhibited depending on the reaction conditions, which is not preferable.

Moreover, as a metal ion contained in a polyimide film, there exist Na ^<+> , K ^<+> , Ca ^{< 2+ >} , for example, It is preferable that the density ^| concentration of a metal ion is 1 microgram / g or less in the following quantitative methods. This is to prevent contamination of the wafer. The same applies to other protective materials or liners, and the concentration of metal ions is preferably 1 μg / g or less.

Below, it describes about the determination method of a metal ion. Collect about 1 g of sample (protective material or polyimide film) in a pre-washed bottle (TPX bottle), add 50 mL of ultrapure to the bottle, cover it, and perform boiling extraction at 120 ° C for 1 hour in a dryer. It was. After the extraction, the supernatant is prepared as a 0.01N nitric acid solution and subjected to semi-quantitative analysis by ICP-MS. The following are illustrated as an analyzer and its measurement conditions.
Analysis device: Perkin Elmer, ELAN DRCII
RF output: 1.5 kW
Plasma gas: Ar17L / min
Nebulizer: Coaxial nebulizer manufactured by Teflon (registered trademark) Measurement mode: Semi-quantitative analysis DRC mode: OFF (m / z 6-15, m / z 90-210, m / z 230-240), ON (m / z 19- 89)
Concentration calculation method:
Various element concentrations in samples (μg / g)
= {Element concentration in measurement solution (ng / mL)
-Element concentration in BLANK (ng / mL)}
× Liquid volume (mL) / {sample amount (g) × 1000}

Further, it is preferable that water from the polyimide film, nitrogen or oxygen each occurrence gas is 1.0E + 20 / cm ² or less. This is because it is required that these gas generations do not adversely affect a predetermined reaction in the process chamber.

In the present invention, the protective material installed in the vicinity of the wall surface of the process chamber is characterized by having electrical insulation and self-supporting properties. This protective material preferably has at least a polyimide film. It is preferable to form this polyimide belt in a cylindrical shape. In addition, it is preferable that the thickness of the polyimide film is 25 μm or more to have a plasma electric barrier thickness sufficient to protect the process chamber wall surface. More preferably, the thickness of the polyimide film is in the range of 50 μm or more and 150 μm or less, and the glass transition point is more preferably 250 ° C. or more. Moreover, it is preferable that the water absorption rate of a polyimide film is 3% or less. The volume resistivity of the polyimide film is preferably 10 ¹⁶ Ω · cm or more. The reason why these are preferable is as described above.

In the present invention, a cylindrical member that protects the inner wall surface of a vacuum reaction tank (an example of a process chamber) is provided with a self-supporting liner made of seamless polyimide film so that it can be easily detached from the apparatus and frequently maintained. A cylindrical member that protects the inner wall surface of a vacuum reaction vessel such as a necessary dry etching apparatus or a PVD apparatus with a large amount of deposits can be made clean in a timely manner as necessary.

<Liner / Protective Material>
When the protective material or liner is used in a vacuum reaction tank, it is desirable that the amount of outgas is small under vacuum. This is because it is necessary that outgas generation does not adversely affect a predetermined reaction in the process chamber.

  In addition, when the protective material or liner is used in an apparatus for generating plasma, it is exposed to plasma, so that plasma resistance is required. For this reason, the thickness of the protective material or liner needs to be a plasma electric barrier thickness sufficient to protect the process chamber wall surface.

  In addition, when the chuck table is used in an apparatus where the chuck table is used at a high temperature of about 400 ° C., heat resistance of about 200 ° C. is also required. That is, the protective material or liner needs to have heat resistance. A cylindrical seamless polyimide film is suitable as one having these characteristics and capable of being easily installed and removed without contaminating the inside of the vacuum reaction layer.

  The protective material or liner is installed in the vicinity of the plasma generation site on the inner wall surface of the process chamber. As the protective material or the liner, a polyimide film can be preferably used, but is not particularly limited thereto, and may be formed of a multilayer form of a polyimide film and another material film. An example of the other material film is a fluororesin film. Moreover, polyarylate is mentioned as an organic material used suitably as a protective material or a liner.

  In the case where the shape of the inner wall surface of the process chamber is cylindrical, it is preferable that the shape of the protective material or liner is formed in a cylindrical shape so as to conform to the dimensions of the inner wall surface of the process chamber.

  Further, it is preferable to form the shape of the protective material or the liner so as to conform to the internal structure of the process chamber and the shape of its parts.

<Manufacture of polyimide film>
A polyimide film that can be used as a suitable example of the protective material or liner will be described below.

  A known polyamic acid solution as a raw material for the polyimide film can be used, and a polyamic acid solution obtained by polymerizing an acid dianhydride and a diamine in a solvent is used. When the aromatic polyimide resin is used, a film having suitable mechanical strength (self-supporting property) and heat resistance can be obtained.

  Examples of suitable acid dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride. Anhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Products, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like.

  On the other hand, examples of the diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3 , 3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, and the like.

  A suitable solvent can be used for the polymerization reaction of these acid anhydrides and diamines, but polar solvents are preferably used from the viewpoint of solubility and the like. Specifically, N, N-dimethylformamide, N , N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, dimethyl sulfoxide, Tetramethylene sulfone, dimethyltetramethylene sulfone, etc. are conceivable. These may be used alone or in combination.

  Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed alone or in combination with the organic polar solvent.

  A polyamic acid solution is obtained by reacting the acid anhydride (a) and the diamine (b) in an organic polar solvent. The monomer concentration (concentration of (a) + (b) in the solvent) at that time is set according to various conditions, but is preferably 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or less, particularly preferably 5 to 50 ° C., and the reaction time is preferably 0.5 to 10 hours.

  In order to form the polyimide film in a cylindrical shape, the viscosity of the polyamic acid solution applied to the cylindrical mold is preferably about 10 to 10000 poise, preferably about 50 to 5000 poise (B-type viscometer, 23 ° C.). If the viscosity is 10 poises or less, so-called sagging or repellency of the coating layer is likely to occur, and it becomes difficult to obtain a uniform coating thickness. On the other hand, if it exceeds 10,000 poise, it is necessary to apply a high pressure at the time of discharge, and the leveling effect by centrifugal molding is difficult to be obtained, which is not preferable.

The method for producing a polyimide film preferably includes the following steps.
(1) The preparation process which prepares the resin solution which has a polyamic acid solution as a main component.
(2) A coating process for coating the resin solution on the inner surface of the cylindrical mold.
(3) Centrifugal molding step for centrifugal molding to make the surface of the resin film formed by application uniform.
(4) Imide conversion step of removing solvent and converting imide after centrifugal molding.

  The application process is exemplified by a method in which a resin solution containing a polyamic acid solution as a main component is applied to the inner surface of a cylindrical mold by moving the cylindrical mold in the axial direction of the dispenser while rotating. However, the present invention is not particularly limited thereto. For example, a resin solution containing a polyamic acid solution as a main component may be attached to the inner surface of the mold with a dispenser or the like, and then finished to a predetermined thickness with a hard sphere or the like. .

  The centrifugal molding step is centrifugal molding in which a mold to which a resin solution is applied is rotated, and the applied resin film is smoothed and defoamed.

  Here, the rotational speed in the circumferential direction of the mold performed for centrifugal molding depends on the diameter of the mold, the viscosity of the resin solution (or the polyamic acid solution that is the main component thereof), and the application state, but is 100 rpm or more and 5000 rpm or less. Is preferred. If it is 100 rpm or less, the leveling effect and defoaming effect of the coating film due to centrifugal force are difficult to obtain, and if it exceeds 5000 rpm, the mechanical load increases and the mold is eccentric due to vibration, and the coating thickness in the longitudinal direction of the mold Is not preferable.

  In the imide conversion step, the resin film is solidified or cured by heating or solvent extraction, and further imide conversion is performed by heating at a high temperature. In addition, the imide conversion after centrifugal molding may be performed by raising the mold to the imide conversion temperature or higher to form a polyimide belt, or the belt that is stopped in a state where the resin film in the mold is heated and solidified is removed from the mold. The imide conversion may be performed after taking out and replacing the belt with a metal pipe.

  By the above manufacturing method, a cylindrical seamless film can be formed, and a self-supporting polyimide film can be formed by forming the film thickness to a predetermined thickness. The thickness of the film is preferably 25 μm or more, and more preferably 50 μm or more.

In the present invention, the method for fixing the cylindrical seamless polyimide film to the inner wall of the vacuum reaction tank is not particularly limited. For example, a double-sided tape structure may be bonded to the polyimide film surface, and the polyimide film may be provided on the inner wall of the vacuum reaction tank via the double-sided tape. Alternatively, a pressure sensitive adhesive is applied to the surface of the polyimide film using a known method such as casting, spin coating, roll coating, etc., and dried at a temperature necessary for removing the solvent. It may be provided on the inner wall of the vacuum reaction tank. Furthermore, known methods such as electrodeposition coating and thermocompression bonding can be used.
Hereinafter, the present invention will be described based on examples. In addition, this invention is not limited to a following example.

[Outgas analysis]
Thermal desorption mass spectrometry (TDS-MS) method apparatus: EMD-WA1000SW (manufactured by Electronic Science)
Temperature rise conditions: Temperature rise to a temperature equivalent to 400 ° C. at the test dish surface temperature (600 ° C. at the sample stage temperature) (Temperature increase rate at the sample stage temperature = 30 ° C./min)
(After setting the sample, wait for the temperature to fall to 1 to 2 × 10 ⁻⁸ Torr or less, then start heating)
Analysis: SCAN method (mass spectrum measurement: mass range = 0 to 199)
Sample area: about 0.25 cm ²
Sample holding: Black special sample pan is used (sample size: about 5 mm x 5 mm (about 0.25 cm ² ))

[Volume resistivity evaluation]
The volume resistance is a value measured by a method according to JIS C 2318 (JIS C 2115.11 volume resistivity) in a constant temperature and humidity chamber of 23 ° C./65% RH for 24 hours or more in the same environment. . The applied voltage is 100V.

[Evaluation of water absorption]
The water absorption is the weight change after immersion of the polyimide film in distilled water at 23 ° C. for 1 hour (measured under the same conditions as in the measurement of w2: w1) with respect to the weight (w1) before immersion. It is calculated as a water absorption rate by the equation.
(Equation 1)
Water absorption rate (%) = {(w2-w1) / w1} × 100

[Example 1]
N-methyl-2-pyrrolidone (NMP) 784.5 g was charged, then 157.6 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 57.9 g of p- Phenylenediamine (PDA) was charged at room temperature in a nitrogen atmosphere. After thickening by the polymerization reaction, heating was continued at 70 ° C. for 15 hours to obtain a 120 Pa · s polyamic acid solution.

  This polyamic acid solution was applied to the inner peripheral surface of a drum mold having an inner diameter of 300 mm and a length of 500 mm with a dispenser so that the final thickness was 75 μm, and rotated at 1500 rpm for 10 minutes to obtain a uniform spread layer (resin film ) Subsequently, the solvent was removed by heating for 30 minutes while rotating the drum mold at 250 rpm in a 120 ° C. drying furnace in which hot air was circulated uniformly. Furthermore, the temperature was raised to 360 ° C. at a rate of 2 ° C./min, and heating was continued for 10 minutes as it was to proceed with imidization. Subsequently, after cooling to room temperature, it peeled from the metal mold | die inner surface, and obtained the 75-micrometer polyimide film.

  This polyimide film with a thickness of 75 μm (K type manufactured by Nitto Denko Corporation) was produced in the same dimensions as the chamber wall of the 300 mm PVD apparatus, and was installed in the PVD apparatus as the chamber wall. Then, after confirming that the degree of vacuum could be maintained by a normal operation, the PVD apparatus was operated for 200 hours. Thereafter, the process chamber was opened, and the chamber wall made of the polyimide film was taken out.

Compared with the conventional chamber wall, the weight is light and there was no problem in taking it out. Moreover, the chamber wall which consists of a polyimide film of a present Example was able to be installed and removed easily. Table 1 shows the outgas evaluation of the polyimide form. The results of volume resistivity and water absorption evaluation are shown in Table 2. Moreover, when measuring the metal ion in a polyimide film using said quantification method, Na ^<+> , K ^<+> , Ca ^{< 2+ >} is detected as a metal ion, and each element concentration is 1 microgram / g or less. Met.

[Example 2]
Create a polyimide cover film with pressure-sensitive adhesive (made by Toyobo Co., Ltd .: pressure-sensitive adhesive thickness 15 μm, polyimide thickness 25 μm) that matches the shape of the inner wall of the chamber wall of the 300 mm PVD device, and paste this to the inner wall of the chamber wall. A chamber wall provided with polyimide on the inner wall surface was obtained.

  This was installed in a PVD apparatus in the same manner as in Example 1, and the PVD apparatus was operated for 200 hours. Thereafter, the chamber was opened, and the chamber wall provided with polyimide on the inner wall was taken out.

When the polyimide cover film with pressure-sensitive adhesive was peeled off after removal, no deposits were found on the chamber wall of the PVD apparatus. Thereafter, an adhesive-attached polyimide cover film having a shape matched to the inner wall shape of the chamber wall was again bonded to the inner wall of the chamber wall to obtain a chamber wall provided with polyimide on the inner wall surface. The total time required for peeling and pasting this polyimide film was 20 minutes.

  As described above, according to the polyimide film (liner or protective material) of the present invention, it is possible to easily and reliably maintain a process chamber such as a semiconductor manufacturing apparatus. Further, as can be seen from Table 1, the amount of generated gas is suppressed, and the reaction in the process chamber is not affected. Furthermore, as can be seen from Table 2, the volume resistivity is high, and it has sufficient electrical insulation to protect the process chamber wall surface.

  By installing the polyimide film of the present invention on the inner wall of the process chamber or its parts, the inner wall and members can be protected, and attachment and removal are easy, so it is suitable for cleaning and maintenance, and is not cleaned and reused. It can be used as appropriate for disposable applications.

Claims (11)

A process chamber in which a plasma is generated,
A process chamber comprising an electrically insulating liner for protecting the process chamber wall surface in the vicinity of the process chamber wall.   The process chamber of claim 1, wherein the liner is composed of a polyimide film.   The process chamber according to claim 2, wherein the liner has a cylindrical shape and is self-supporting.   The process chamber according to claim 2, wherein the liner has a thickness of 25 μm or more and has a plasma electric barrier thickness sufficient to protect the wall of the process chamber.   4. The process chamber according to claim 2, wherein a thickness of the liner is in a range of 50 μm or more and 150 μm or less, and a glass transition point is 250 ° C. or more.   The process chamber according to claim 2, wherein the liner has a water absorption of 3% or less. The process chamber according to any one of claims 2 to 6, wherein the liner has a volume resistivity of 10 ¹⁶ Ω · cm or more.   The process chamber according to claim 2, wherein a concentration of metal ions contained in the liner is 1 μg / g or less. 9. The process chamber according to claim 2, wherein each gas generated from water, nitrogen, or oxygen from the liner is 1.0E + 20 / cm ² or less.   A protective material having electrical insulation and self-supporting properties, wherein the protective material is provided near a wall surface of a process chamber in which plasma is generated.   The said protective material is a protective material of Claim 10 comprised with a polyimide film.