JP2008124265A - Low-thermal-expansion ceramic member, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-thermal-expansion ceramic member and a manufacturing method thereof wherein the method can be applied widely to low-thermal-expansion ceramic materials even though their kinds are miscellaneous, and the member can stabilize in a long term its inner electrodes formed in the surface of its low-thermal-expansion ceramic dielectric portion, and further, the structure of the member is so made hard to damage its dielectric portion too that its performance as an electrostatic chuck can be stabilized in a long term. <P>SOLUTION: The low-thermal-expansion ceramic member has a low-thermal-expansion ceramic base, electrodes provided on the low-thermal-expansion ceramic base, and a low-thermal-expansion ceramic dielectric portion for covering the electrodes. The structure of each electrode is the laminated structure comprising a first layer made of the nitride or composite nitride of periodic-table IVa-group elements, the nitride or composite nitride of periodic-table Va-group elements, or the nitride or composite nitride of periodic-table VIa-group elements, and comprising a second layer made of periodic-table IVa-, Va-, or VIa-group elements. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low thermal expansion ceramic member suitable for an electrostatic chuck or heater for holding a semiconductor substrate used in a semiconductor device manufacturing apparatus.

  Conventionally, ceramics such as alumina, silicon nitride, and silicon carbide have been widely used for members such as wafer support jigs in the manufacturing process of semiconductor devices.

  However, when the exposure apparatus starts to require positioning accuracy of less than 0.01 μm with the miniaturization of the semiconductor device, ceramics having a high thermal expansion coefficient such as alumina, silicon nitride, silicon carbide and the like cannot be dealt with. This is because the influence of temperature is large and such extremely fine positioning is difficult.

  For this reason, in order to satisfy the above requirements, in recent years, development of electrostatic chucks using ceramics having a low coefficient of thermal expansion of 0.6 ppm / K or less has become active. Such a technique is described in Patent Documents 1 to 3, for example.

  In Patent Document 1, cordierite quality is described as an example of low thermal expansion ceramics, and plates of heat resistant metals such as W and Mo are described as examples of electrodes. In addition, as an example of the electrode, there is a description that a conductive layer may be formed by printing a slurry made of a conductive powder such as W, Mo and TiN and cordierite powder.

  In Patent Document 2, as examples of low thermal expansion ceramics, compounds having a negative thermal expansion coefficient (for example, β-eucryptite and cordierite) and compounds having a positive thermal expansion coefficient (for example, silicon carbide and silicon nitride) are disclosed. Etc.) and W mesh is described as an example of the electrode.

  In Patent Document 3, an internal electrode is formed using a W or Mo foil or mesh sheet which is a metal having a low thermal expansion ceramic with an average particle size of 6 μm or less and a small thermal expansion difference from the low thermal expansion ceramic. It is described.

JP 2001-313332 A JP 2003-273203 A JP 2005-228934 A

  As a technique described in Patent Document 1 or 2, a method of obtaining an electrostatic chuck structure by using an electrode material such as a metal plate or a mesh electrode as an internal electrode and simultaneously firing with a low thermal expansion ceramic is generally used. There are the following two. One is a method of digging a groove for embedding an electrode material in a low thermal expansion ceramic plate. The other is a method of sandwiching and sintering an electrode material with ceramic raw material powder having a thickness of the electrostatic chuck.

  However, in the method of digging a groove, when the groove is deeper than the thickness of the electrode material, a gap is formed between the electrode material and a portion that functions as an electrostatic chuck by applying a voltage (hereinafter referred to as a dielectric portion). As a result, the dielectric portion may not be driven according to the applied voltage. For this reason, the groove is formed shallower than the thickness of the electrode material, and an electrode material having a thermal expansion larger than that of the dielectric portion is pressed into the dielectric portion. However, according to the study by the present inventors, since the residual stress is acting on the dielectric portion, even if it seems that there is no problem immediately after sintering, by using it for a long time (for example, about 200 hours), It turns out that there is a problem of cracking.

  In addition, since the technique described in Patent Document 3 is intended to suppress cracks caused by the electrode material by limiting the particle size of the ceramic, it is widely applied to various low thermal expansion ceramics. Can not. Moreover, since it is necessary to control the particle size of the ceramic, there are concerns that the manufacturing conditions are limited and the manufacturing cost is increased.

  The present invention can be widely applied to various low thermal expansion ceramic materials, and the internal electrode formed on the surface of the dielectric portion of the low thermal expansion ceramic can have a stable structure for a long period of time. Another object of the present invention is to provide a low thermal expansion ceramic member capable of stabilizing the performance as an electrostatic chuck for a long period of time by using a structure in which residual stress due to manufacturing is difficult to be applied, and a manufacturing method thereof.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has come up with the following aspects of the invention.

(1) It has a low thermal expansion ceramic substrate, an electrode provided on the low thermal expansion ceramic substrate, and a low thermal expansion ceramic dielectric portion covering the electrode, and the structure of the electrode is a group IVa element of the periodic table A first layer composed of a nitride or a composite nitride of the periodic table Va group element, or a nitride or a composite nitride of the periodic table group VIa element, and a periodic table IVa, Va Alternatively, a low thermal expansion ceramic member characterized by having a laminated structure of a second layer made of a VIa group element.

  (2) The low thermal expansion ceramic member according to (1), wherein the first layer is made of a nitride of Ti or a composite nitride, and the second layer is made of Ti.

  (3) The low thermal expansion ceramic member according to (1), wherein the first layer is made of Cr nitride or composite nitride, and the second layer is made of Cr.

  (4) The low thermal expansion ceramic member according to any one of (1) to (3), wherein the electrode has a thickness of 3 μm or more.

(5) The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic base are MgO: 8 to 17.2% by mass, Al ₂ O ₃ : 22 to 38% by mass, SiO ₂ : 49.5 to 70% by mass, and li ₂ O: 0.1 to 2.5 wt%, characterized in that it contains (1) to the low thermal expansion ceramic member according to any one of (4).

(6) The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic base further contain one or more compounds of transition metals excluding Ti (as oxides): 0.1 to 2% by mass, the mass of SiO ₂ [SiO _2], mass [LiO _2] of LiO _2, the mass of MgO [MgO], when representing the mass of the Al ₂ O ₃ and _{[Al 2 O 3], (} [SiO 2 ] −8 × [Li ₂ O]) / [MgO] ≧ 3 and ([SiO ₂ ] −8 × [Li ₂ O]) / [Al ₂ O ₃ ] ≧ 1.2 are satisfied. The low thermal expansion ceramic member according to (5), wherein

  (7) The low thermal expansion ceramic dielectric portion and the low thermal expansion ceramic base further contain one or more rare earth elements (as oxides): 10% by mass or less (5 Or a low thermal expansion ceramic member according to (6).

(8) The low thermal expansion ceramic dielectric portion and the low thermal expansion ceramic base further include at least one selected from the group consisting of a Ti compound (in terms of TiO ₂ ): 1% by mass or less and C: 5% by mass or less. The low thermal expansion ceramic member according to any one of (5) to (7), which is contained.

  (9) Forming an electrode on the first low thermal expansion ceramic material, and joining the second low thermal expansion ceramic material to the first low thermal expansion ceramic material, thereby providing the first and second low thermal expansion ceramic materials. Sandwiching the electrode with a ceramic material, and as the electrode, a nitride or composite nitride of a periodic table group IVa element, a nitride or composite nitride of a group Va element of the periodic table, or Forming a layer having a laminated structure of a first layer made of a nitride or a composite nitride of a group VIa element of the periodic table and a second layer made of a group IVa, Va or VIa element of the periodic table A method for producing a low thermal expansion ceramic member.

  (10) As described in (9), the first layer is formed of Ti nitride or composite nitride, and the second layer is formed of Ti. A method for producing a low thermal expansion ceramic member.

  (11) As described in (9), the first layer is made of Cr nitride or composite nitride, and the second layer is made of Cr. A method for producing a low thermal expansion ceramic member.

  (12) The method for producing a low thermal expansion ceramic member according to any one of (9) to (11), wherein the thickness of the electrode is 3 μm or more.

(13) as said first and second low thermal expansion ceramic materials, MgO: from 8 to 17.2 wt%, Al ₂ O _3: 22 to 38 wt%, SiO _2: 49.5 to 70 wt%, and Li _The method for producing a low thermal expansion ceramic member according to any one of (9) to (12), wherein a material containing ₂ O: 0.1 to 2.5% by mass is used.

(14) As said 1st and 2nd low thermal expansion ceramic material, 1 type or 2 types or more of transition metals except Ti (in oxide conversion): 0.1-2 mass% is further contained, SiO. the _second mass [SiO _2], the mass of the LiO ₂ [LiO _2], the mass of MgO [MgO], when representing the mass of the Al ₂ O ₃ and _{[Al 2 O 3], (} [SiO 2] −8 × [Li ₂ O]) / [MgO] ≧ 3 and ([SiO ₂ ] −8 × [Li ₂ O]) / [Al ₂ O ₃ ] ≧ 1.2 are satisfied. What is used is a manufacturing method of the low thermal expansion ceramic member as described in (13) characterized by the above-mentioned.

  (15) The first and second low thermal expansion ceramic materials further include one or two or more rare earth element compounds (as oxides): those containing 10% by mass or less. The method for producing a low thermal expansion ceramic member according to (13) or (14).

(16) The first and second low thermal expansion ceramic materials further include at least one selected from the group consisting of a Ti compound (in terms of TiO ₂ ): 1% by mass or less and C: 5% by mass or less. The method for producing a low thermal expansion ceramic member according to any one of (13) to (15), wherein:

  (17) The method for producing a low thermal expansion ceramic member according to any one of (9) to (16), wherein the first and second layers are formed by physical vapor deposition.

  According to the present invention, the electrode can be used stably for a long period of time, and it has a structure in which residual stress due to manufacturing is hardly applied to the dielectric part. Can be demonstrated.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a low thermal expansion ceramic member according to an embodiment of the present invention.

  In this embodiment, as shown in FIG. 1, the groove | channel 4 is formed in the surface of the low thermal expansion ceramic base | substrate 2, and the electrode 3 is embedded in the inside. And the dielectric part 1 which consists of low thermal expansion ceramics is arrange | positioned on these.

  The dielectric part 1 and the low thermal expansion ceramic substrate 2 are both made of low thermal expansion ceramics. The material of the low thermal expansion ceramic is not particularly specified as long as the coefficient of thermal expansion is small, but it is preferable to use a material of 0.6 ppm / K or less because of industrial demand. As the low thermal expansion ceramic satisfying this thermal expansion coefficient, for example, a ceramic mainly composed of cordierite, eucryptite, sponge turumene, zirconyl phosphate, or the like can be used.

  The electrode 3 includes (A) a layer (first layer) composed of at least one “nitride or compound nitride of periodic table IVa, Va or VIa group element”, and (B) at least one “periodic table”. A layer (second layer) made of “IVa, Va or VIa group element” is laminated on each other. That is, the first layer is composed of a nitride or composite nitride of group IVa element of the periodic table, a nitride or composite nitride of group Va of the periodic table, or a nitride or composite nitride of group VIa of the periodic table It is composed of For example, a metal nitride layer or composite nitride layer that is a layer of “nitride or composite nitride of Group IVa, Va, or VIa element” and a layer of “Group IVa, Va, or VIa group element” And a metal nitride layer or a composite nitride layer are laminated in this order.

  Since the electrode 3 is fixedly disposed between the dielectric portion 1 and the base 2, when the electrode 3 is composed only of a metal nitride layer or a composite nitride layer, long-term stability is ensured. If the electrode 3 is made thicker, the adhesiveness is lowered and the resistance to deformation is lowered. This is because the internal stress of the metal nitride layer or the composite nitride layer constituting the electrode 3 is increased. On the other hand, if the electrode 3 is thinned to suppress internal stress, long-term stability cannot be ensured.

  In order to make these points compatible, the inventors of the present application have made extensive studies. As a result, the electrode 3 has a laminated structure as described above, so that the metal layer functions as a stress relaxation layer. It has been found that the internal stress can be reduced, and as a result, even if the electrode 3 is thickened, it is possible to prevent a decrease in adhesion and a decrease in deformation resistance.

  Further, when the electrode 3 is composed only of a metal nitride layer or a composite nitride layer, its resistance is high, so that heat is generated due to resistance during long-time use, and cracks that may be caused by thermal deformation are generated in the electrode 3. Can happen. On the other hand, in this embodiment, even if heat is generated in the metal nitride layer or the composite nitride layer, this heat is extracted through the metal layer having a high thermal conductivity, so that thermal deformation is suppressed. It is possible. In other words, even if heat is generated, the heat is diffused throughout the electrode 3 through the metal layer, and local temperature rise can be suppressed and thermal deformation can be suppressed. Also from this point, according to the present embodiment, it can be said that the stability of the electrode 3 is improved.

  The metal element constituting the “metal nitride layer or composite nitride layer” is a low thermal expansion ceramic that hardly reacts with the dielectric portion 1 and the substrate 2 which are low thermal expansion ceramics and is resistant to deformation due to thermal expansion. It is necessary to have the property of having high adhesiveness. From this point, it must be a periodic table IVa, Va or VIa group element. Here, the elements in the periodic table IVa, Va or VIa are not particularly specified, but Ti, Ta, and Cr can be mentioned respectively.

  Further, as the metal element constituting the “metal layer”, the same metal element as that of the “metal nitride layer or composite nitride layer” is preferably used. When a composite nitride layer is used, it is preferably a composite metal layer or a metal layer that is a main component of the composite nitride. For example, when a TiAlN layer is used, a TiAl layer or a Ti layer is preferable. Thus, by using the same metal element as that of the metal nitride layer or the like, when these layers are formed by a physical vapor deposition method (PVD method) described later, the atmosphere gas is simply replaced without changing the target. Since it improves, it can be said that it is suitable.

  Further, a conductive metal nitride layer such as TiN or CrN or a composite nitride layer such as TiAlN hardly reacts with the low thermal expansion ceramic substrate 2 and is easily formed by the PVD method. Also, the adhesion of these layers to the low thermal expansion ceramic substrate 2 is good. Therefore, a conductive metal nitride layer such as TiN or CrN or a composite nitride layer such as TiAlN is preferable.

  The thickness of the electrode 3 is preferably 3 μm or more. When the thickness of the electrode 3 is less than 3 μm, heat is generated due to the resistance of the electrode 3 during long-time use, and cracks that are thought to be caused by thermal deformation are likely to occur in the electrode 3. As a result, the resistance of the electrode 3 increases, and there is a risk of further heat generation during use. Further, if the use is further continued, cracks may develop and it may be difficult for the electrode 3 to conduct.

  Further, the upper limit of the thickness of the electrode 3 is not particularly defined, but is preferably set to 80 μm, for example. The thicker electrode 3 is preferable from the viewpoint of the stability of the electrode. However, when manufacturing is considered industrially, it takes too much time to form a thicker than 80 μm by the PVD method described later, and the target material is damaged. As a result, the uniformity of the film tends to be impaired. Therefore, the thickness of the electrode 3 is preferably 80 μm or less, for example.

  Moreover, the thickness of the metal layer constituting the electrode 3 is not particularly specified, but is preferably 0.01 μm to 0.06 μm. When the thickness of the metal layer is less than 0.01 μm, the internal stress is hardly relaxed, and therefore there is a possibility that it exceeds 2 GPa, which is an allowable value of internal stress based on experimental knowledge. Moreover, there is a concern that the adhesiveness with the low thermal expansion ceramic substrate 2 is deteriorated and it is likely to be weak against deformation. On the other hand, when the thickness of the metal layer exceeds 0.06 μm, when a metal nitride layer or a composite nitride layer is formed with the metal layer interposed therebetween, the structure of these layers (columnar crystals) becomes difficult to be continued, and stress is applied. Although it can be relaxed, it is easily peeled off from the interface portion between the metal layer and the metal nitride or composite nitride layer against deformation due to thermal expansion. Therefore, in order to achieve both relaxation of stress and improvement of adhesion, the thickness of the metal layer is preferably 0.01 μm to 0.06 μm.

  When a plurality of metal layers are used, it is preferable to sandwich a metal nitride layer or composite nitride layer having a thickness of 1.5 μm to 4.5 μm between them. That is, the interval between the metal layers is preferably 1.5 μm to 4.5 μm. If the distance between the metal layers is less than 1.5 μm or more than 4.5 μm, the internal stress exceeds 2 GPa, the adhesion to the low thermal expansion ceramic substrate 2 is likely to be reduced, and the deformation resistance It tends to be weak. Therefore, the interval between the metal layers is preferably 1.5 μm to 4.5 μm. The internal stress can be obtained by, for example, X-ray diffraction.

  Further, as the low thermal expansion ceramic constituting the dielectric portion 1 and the low thermal expansion ceramic substrate 2, it is preferable to use one having a thermal expansion coefficient of 0.6 ppm / K or less. However, when this low thermal expansion ceramic member is used as a member for a semiconductor device manufacturing apparatus, it is preferable to satisfy weight reduction and increase in resonance frequency in order to improve the throughput of the semiconductor device manufacturing apparatus. Therefore, it is preferable not only to have a coefficient of thermal expansion of 0.6 ppm / K or less, but also to obtain high rigidity.

Therefore, the present inventors conducted various tests and studies based on this viewpoint. As a result, as a low thermal expansion ceramic, the chemical composition is MgO: 8 to 17.2 mass%, Al ₂ O ₃ : 22 to 38 mass%, SiO ₂ : 49.5 to 70 mass%, Li ₂ O: 0.00. It has been found that those in the range of 1 to 2.5% by mass can be stably produced as a highly rigid material. For example, it has a high Young's modulus of 100 GPa or more and a sufficiently low thermal expansion coefficient of about 0.02 ppm / K, and there are few pores and microcracks, and high surface accuracy can be obtained. Here, if these components are out of the range, the coefficient of thermal expansion becomes large or the rigidity is lowered.

Furthermore, when this low thermal expansion ceramic member is used as a member for exposure or measurement of characteristics when manufacturing a semiconductor device, this member should be blackened to avoid irregular reflection of light. Is preferred. Based on this viewpoint, the present inventors conducted various tests and examinations. As a result, one or more compounds of transition metals excluding Ti were further added to the above composition (as oxides): 0.1 2 mass% is added, and regarding the mass ratio of the chemical composition, the relationship of ([SiO ₂ ] −8 × [Li ₂ O]) / [MgO] ≧ 3 and ([SiO ₂ ] −8 × [Li It has been found that a sufficient black color tone can be obtained when the relationship of ₂ O]) / [Al ₂ O ₃ ] ≧ 1.2 is satisfied. Here, [SiO _2] represents the mass of SiO _2, [LiO _2] represents the mass of LiO _2, [MgO] represents the mass of MgO, the mass of [Al ₂ O _3] is Al ₂ O ₃ Represents. In addition, it is preferable to use 1st transition metals, such as Cr, Mn, Fe, Co, Ni, Cu, as a transition metal except Ti. Examples of these compounds include oxides, nitrides, carbides and the like, and the above values of 0.1 to 2% by mass are values when these are all converted to oxides.

Here, the above relations “([SiO ₂ ] −8 × [Li ₂ O]) / [MgO] ≧ 3” and “([SiO ₂ ] −8 × [Li ₂ O]) / [Al ₂ O”. ₃ ] ≧ 1.2 ”means that in the case of MgO—Al ₂ O ₃ —SiO ₂ which is a main component of low thermal expansion ceramics, the black color becomes lighter when the amount of SiO ₂ is reduced. The amount of SiO ₂ is determined by the ratio to the amount of MgO and Al ₂ O ₃ . This relationship has been experimentally derived, but LiO ₂ fixes SiO ₂ as a LiO ₂ —Al ₂ O ₃ —SiO ₂ sintered body during sintering. Of SiO ₂ is subtracted.

  Furthermore, when high rigidity is required, it is preferable that one or more of rare earth elements (as oxide): 10% by mass or less is added to the above composition. It was discovered by the present inventors. Examples of rare earth elements include Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Examples of these compounds include oxides, nitrides, and carbides. The value of 10% by mass or less is a value when all of these are converted into oxides. Among these rare earth elements, Y is preferable because it is easily available and inexpensive. In addition, the lower limit value of the addition amount of the rare earth element is not particularly specified, and if it is added, the rigidity is improved.

Further, when it is required to speed up the movement of charges in the dielectric part 1 such as when used in an electrostatic chuck, it is preferable to reduce the resistance of the dielectric part 1. Based on this viewpoint, the present inventors conducted various tests and examinations. As a result, the composition further includes at least one of a Ti compound (in terms of TiO ₂ ): 1% by mass or less and C: 5% by mass or less. It has been found that the resistance of the dielectric part 1 can be lowered when added. Here, examples of the Ti compound include titanium oxide, titanium nitride, and titanium carbide. Moreover, said value of 1 mass% or less is a value when these are all converted into titanium oxide. In addition, the lower limit value of the addition amount of the Ti compound (in terms of TiO ₂ ) is not particularly defined, and if added, the resistance can be reduced and the movement of charges can be accelerated. Further, the lower limit value of the addition amount of C is not particularly specified, and if C is added, the resistance can be reduced and the movement of charges can be accelerated.

Such a low thermal expansion ceramic member according to this embodiment has a high Young's modulus of 100 GPa or more and a sufficiently low thermal expansion coefficient of about 0.02 ppm / K as described above, and there are few pores and microcracks, High surface accuracy can be obtained. In addition, when a rare earth element is added, a transition metal is added, and Ti or C is added, the coefficient of thermal expansion is about 0.6 ppm / K, but exhibits a high Young's modulus of 120 GPa or more, While exhibiting black color, the volume resistivity is 1 × 10 ¹⁰ Ωcm or more and less than 1 × 10 ¹² Ωcm. As a result, irregular reflection of light is suppressed, it is possible to drive at a low voltage, and the response time is shortened. Therefore, it can be said that the member is suitable for an electrostatic chuck that performs electrostatic attraction.

  Here, the Young's modulus can be measured at room temperature by an ultrasonic pulse method according to JIS-R1602. The coefficient of thermal expansion can be measured at room temperature (25 ° C.) with a double optical path Michelson laser interferometer type thermal expansion measuring instrument based on JIS-R3251. The volume resistivity can be measured using a high resistance meter 4339B (manufactured by Agilent Technologies).

  Next, an outline of a method for manufacturing a low thermal expansion ceramic member according to an embodiment of the present invention will be described.

  In this method, first, the electrode 3 having the above laminated structure is formed on the surface of the low thermal expansion ceramic material for the dielectric portion 1. For example, a predetermined pattern is formed as the electrode 3. Next, the low thermal expansion ceramic material for the dielectric portion 1 is bonded to the low thermal expansion ceramic base 2 on which the grooves 4 along the pattern of the electrode 3 are formed. As a result, the electrode 3 becomes an internal electrode. By such a method, a low thermal expansion ceramic member can be manufactured.

  Next, details of each process in the above method will be described.

  Examples of the method for forming the electrode 3 on the surface of the low thermal expansion ceramic material for the dielectric part 1 include paste baking and vapor phase method. Examples of the vapor phase method include a vapor deposition method, a sputtering method, a physical vapor deposition method (PVD method) such as an ion plating method (IP method), a chemical vapor deposition method (CVD method), and a thermal spraying method.

  In order to stabilize the electrode 3 (internal electrode) for a long time, not only the uniformity in the surface direction of the electrode 3 but also the uniformity in the thickness direction is important. Because, when the uniformity of the electrode 3 is low and there is a gap, the portion where the gap is present has higher resistance than the other portions. This is because there is a high possibility of cracks in the electrode 3. Therefore, in order to form the electrode 3 (internal electrode) that is stable for a long period of time, it is important to obtain good uniformity in both the surface direction and the thickness direction. From this viewpoint, the PVD method is most preferable.

  As described above, the thickness of the electrode 3 is preferably 3 μm or more. This is because if the thickness of the electrode 3 is less than 3 μm, the resistance to deformation caused by heat generation during use is low, and the electrode 3 is easily affected by the deformation. In order to form the electrode 3 having such a thickness, it is preferable to apply a PVD method such as a sputtering method or an ion plating method. In particular, the ion plating method is considered to be a more preferable method from an industrial point of view when forming a thick film of about several tens of μm because the film formation rate is faster than the sputtering method (for example, “surface modification”). "Quality Technology" (see the Research Subcommittee on Surface Modification of the Japan Society for Precision Engineering).

  In forming the electrode 3, a mask is formed in advance to cover a region other than the region where the electrode pattern of the low thermal expansion ceramic material for the dielectric portion 1 is to be formed. Then, a metal nitride layer or a composite nitride layer, a metal layer, a metal nitride layer, or a composite nitride layer are sequentially formed by the PVD method so as to correspond to the electrode pattern. Note that when these layers are formed by the PVD method, it is possible to use targets of the same element. In this case, the atmospheric gas may be nitrogen when forming the metal nitride layer or the composite nitride layer, and the atmospheric gas may be argon when forming the metal layer. In this way, it is possible to easily create two types of layers by simply changing the atmosphere gas and without changing the target. It is possible to dare to change the element used for the target, but in that case, it is necessary to release the vacuum in the chamber and replace the target, which is efficient in consideration of industrial production. Absent. Therefore, a method of changing only the gas type using a target of the same element is preferable.

  In the joining of the low thermal expansion ceramic material for the dielectric portion 1 and the low thermal expansion ceramic substrate 2 in which the grooves 4 are formed, for example, after these positions are aligned, hot pressing (HP) or hot isostatic pressure is performed. What is necessary is just to perform pressurization heat processing, such as a press (HIP). In this pressurizing heat treatment, a ceramic powder made of the same material is interposed between the low thermal expansion ceramic material for the dielectric portion 1 and the low thermal expansion ceramic substrate 2 so that the pressurizing heat treatment is performed. It is preferable to sinter.

  In addition, as a method of forming the groove 4 following the electrode pattern in the low thermal expansion ceramic substrate 2, a method of masking a portion excluding a portion corresponding to the electrode pattern and performing a blast treatment, and a groove by precision machining. Examples of the method include processing, and the method is not particularly limited.

  In addition, when there is a demand to use a low thermal expansion ceramic material for the dielectric portion 1 and a low thermal expansion ceramic constituting the low thermal expansion ceramic substrate 2, the above-mentioned elements are used. What is necessary is just to mix | blend each raw material so that it may become predetermined | prescribed content. In particular, when high-rigidity low thermal expansion ceramics are used, solid phase diffusion bonding can be performed during the pressure heat treatment, and a homogeneous electrostatic chuck having no gaps or the like on the bonding surface can be obtained. Specifically, the low thermal expansion ceramic material and the low thermal expansion ceramic substrate 2 for the dielectric portion 1 can be sufficiently joined by simply performing a pressure heat treatment by bringing them together, but using a highly rigid low thermal expansion ceramic. In some cases, sufficient bonding can be achieved simply by applying a weight after the alignment and performing heat treatment. Therefore, the joining using the heating furnace which is not equipped with the pressurization processing equipment can also be made sufficient.

  Moreover, the low thermal expansion ceramic material and the low thermal expansion ceramic base 2 for the dielectric part 1 can be obtained by mixing each oxide raw material, forming the obtained mixed powder, and sintering it. In addition, you may further perform calcination and / or granulation of raw material powder as needed.

  If the surface of the low thermal expansion ceramic is easy, the electrode 3 may be formed in the groove 4 instead of on the low thermal expansion ceramic material for the dielectric portion 1. In this case, after the electrode 3 is formed in the groove 4 that follows the electrode pattern of the low thermal expansion ceramic substrate 2, the low thermal expansion ceramic substrate 2 and the electrode 3 are surfaced, and then the low thermal expansion for the dielectric portion 1 is performed. What is necessary is just to join the expansion ceramic material and the low thermal expansion ceramic substrate 2. Also by this method, the electrode 3 becomes an internal electrode.

  Hereinafter, based on an Example, this invention is further demonstrated.

(Example 1)
In Example 1, first, MgO: 13 wt%, Al ₂ O _3: 32 wt%, SiO _2: 54 wt%, Li ₂ O: 0.6 wt%, TiN (TiO ₂ basis): 0.1 %, Fe ₂ O ₃ : 0.2 mass%, C: 0.1 mass%, a low thermal expansion ceramic sintered body having a composition of 50 mm × 50 mm × 0.5 mm is processed into a dielectric part. The low thermal expansion ceramic material 11 for No. 1 was used. Next, on the surface of the surface of 50 mm × 50 mm, a mask is formed covering the area other than the region where the comb-shaped electrode pattern 12 to be 30 mm × 30 mm as shown in FIG. 2 is to be formed. It mounted in ion plating apparatus AIF-1675SBT. Next, the inside of the chamber of the apparatus is made to reach a vacuum of 10 ⁻⁶ Torr, and then the atmospheric gas is introduced to 8 × 10 ⁻⁴ Torr, and the substrate temperature of the heater that is brought into close contact with the low thermal expansion ceramic material 11 by heater heating is 350 ° C. The temperature was raised to the extent. Then, a comb-shaped electrode pattern 12 constituted by repeatedly laminating a TiN layer and a Ti layer was formed. Subsequently, the mask used for masking was removed.

  In forming the TiN layer and the Ti layer, a TiN layer is used to form a TiN layer having a thickness of 3 μm by performing film formation in nitrogen gas for 45 minutes, and then in Ar gas for 70 seconds. By forming the film, a Ti layer having a thickness of 0.05 μm was formed. Then, after such formation of the TiN layer and the Ti layer was repeated four times, only the TiN layer was formed, and the total thickness of the electrode pattern 12 was about 15 μm.

  Further, a low thermal expansion ceramic sintered body having the same component as the low thermal expansion ceramic material 11 was processed into a 50 mm × 50 mm × 5 mm rectangular parallelepiped, and the electrode pattern 12 was reversely transferred. Next, the portion excluding the portion where the electrode pattern 12 was reversely transferred was masked with a mask, the groove 4 having a depth of 16 μm was formed by blasting, and then the mask was removed. In this way, a low thermal expansion ceramic substrate 2 having grooves 4 having a depth of 16 μm was prepared.

  Then, the thermal expansion ceramic material 11 and the low thermal expansion ceramic substrate 2 are bonded together so that the electrode pattern 12 enters the groove 4 and bonded by hot pressing, and the low thermal expansion ceramic having the internal electrode (electrode pattern 12). An electrostatic chuck was manufactured as a member. As shown in FIG. 3, the hot press conditions were as follows: temperature: 1350 ° C., pressure: 20 MPa, time: 1 hour. In addition, a carbon jig was used during hot pressing, and the atmosphere was an Ar atmosphere.

  Next, when a terminal was connected to the internal electrode through a terminal lead-out portion opened in the low thermal expansion ceramic substrate 2 and a voltage of 100 V was applied to the electrostatic chuck, as shown in FIG. Was 55 kPa, and the leakage current was 0.8 μA. Further, the electrostatic chuck was repeatedly turned on and off at a voltage of 100 V, and the adsorption force and leakage current were measured every 200 hours. As a result, even when the total usage time was 1000 hours, the electrostatic attractive force was 53 kPa, and the leakage current was 0.9 μA. That is, even after 1000 hours of use, the characteristics were hardly deteriorated. In addition, it was confirmed that the life could be about 5 times longer than that of Comparative Example 2 which is a conventional electrostatic chuck described later.

(Examples 2 to 4)
In Examples 2 to 4, as shown in FIG. 3, the thickness and / or the number of layers of the TiN layer and the Ti layer constituting the electrode pattern 12 are different from those in Example 1. In Example 3, the joining method was also changed. And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics in any of the examples, and it was within the measurement error range.

(Example 5)
In Example 5, the composition, thickness, and number of layers constituting the electrode pattern 12 were different from those in Example 1. As for the composition, the ion plating target was changed from Ti to Cr, and a CrN layer and a Cr layer were formed. Moreover, as shown in FIG. 3, joining was performed by hot isostatic pressing in the same manner as in Example 3. And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 6)
In Example 6, the composition of the layer, thickness, and number constituting the electrode pattern 12 was different from that in Example 4. Regarding the composition, the target of ion plating was changed from Ti to Ta, and a TaN layer and a Ta layer were formed. Moreover, as shown in FIG. 3, joining was performed by hot isostatic pressing in the same manner as in Example 3. And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 7)
In Example 7, the electrode pattern 12 was formed by sputtering. First, after masking the low thermal expansion ceramic material 11 as in Example 1, it was placed in a high frequency sputtering apparatus SP-430HS manufactured by ANELVA, and the inside of the chamber was vacuumed to 5 × 10 ⁻⁶ Torr. Thereafter, the atmosphere gas was introduced up to 3 × 10 ⁻³ Torr, and a comb-shaped electrode pattern 12 constituted by repeatedly stacking the TiN layer and the Ti layer was formed. Subsequently, the mask used for masking was removed.

  In forming the TiN layer and the Ti layer, a TiN target is used and a film is formed in nitrogen gas for 90 minutes to form a TiN layer having a thickness of 1.66 μm. A Ti layer having a thickness of 0.01 μm was formed by performing film formation for one minute. Then, after such formation of the TiN layer and the Ti layer was repeated twice, only the TiN layer was formed, and the total thickness of the electrode pattern 12 was about 5 μm.

  Further, a groove having a depth of 6 μm was formed in the low thermal expansion ceramic substrate 2.

  Then, the thermal expansion ceramic material 11 and the low thermal expansion ceramic substrate 2 are bonded together so that the electrode pattern 12 enters the groove 4, and a bonding process is performed by hot isostatic pressing to have an internal electrode (electrode pattern 12). An electrostatic chuck was manufactured as a low thermal expansion ceramic member. In addition, as shown in FIG. 3, the conditions of the hot isostatic press were temperature: 1360 ° C., Ar gas pressurization: 100 MPa, and time: 2 hours. The same applies to the conditions of Examples 3, 5 and 6 above.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 8)
In Example 8, the thickness and the number of TiN layers constituting the electrode pattern 12 and the number of Ti layers were different from those in Example 7. And the test similar to Example 1 was done. As a result, it could be used without problems up to about 800 hours. In other words, it was possible to use 4 times or more of the conventional one without any problem.

Example 9
In Example 9, after forming the electrode pattern 12 in the groove | channel 4 of the low thermal expansion ceramic base | substrate 2, the low thermal expansion ceramic material 11 was joined on this. Specifically, after a pattern of the groove 4 having a depth of 6 μm is formed, a mask is formed around the pattern, and a TiN layer having a thickness of 2.5 μm is formed so as to have a thickness of about 6 μm in the groove 4. A Ti layer having a thickness of 0.01 μm and a TiN layer having a thickness of 3.5 μm were sequentially formed. Thereafter, the surface of the low thermal expansion ceramic substrate 2 was polished to remove the mask, and the outermost TiN layer was scraped 1 mm to obtain an electrode pattern 12 having a thickness of about 5 μm. And the low thermal expansion ceramic material 11 and the low thermal expansion ceramic base | substrate 2 were joined. However, the materials of the low thermal expansion ceramic material 11 and the low thermal expansion ceramic substrate 2 are MgO: 13% by mass, Al ₂ O ₃ : 32.2% by mass, SiO ₂ : 54.2% by mass, Li ₂ O: 0.00%. A low thermal expansion ceramic having a composition of 6% by mass was used.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 10)
In Example 10, the composition and the like of the low thermal expansion ceramics are different from those in Example 1. Specifically, MgO: 13 wt%, Al ₂ O _3: 32.1 wt%, SiO _2: 54.1 wt%, Li ₂ O: 0.6 wt%, Fe ₂ O _3: 0.2 mass %, A low thermal expansion ceramic with the following composition was used.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 11)
In Example 11, the composition and the like of the low thermal expansion ceramics are different from those in Example 1. Specifically, MgO: 12.0 wt%, Al ₂ O _3: 31.1 wt%, SiO _2: 53.1 wt%, Li ₂ O: 0.6 _{wt%, Y 2 O 3: 3} . A low thermal expansion ceramic having a composition of 0% by mass and Cr ₂ O ₃ : 0.2% by mass was used.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Example 12)
In Example 11, the composition and the like of the low thermal expansion ceramics are different from those in Example 1. Specifically, MgO: 12.9 wt%, Al ₂ O _3: 32 wt%, SiO _2: 54 wt%, Li ₂ O: 0.6 wt%, TiO _2: 0.3 wt%, Fe ₂ A low thermal expansion ceramic having a composition of O ₃ : 0.2% by mass was used.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, there was almost no deterioration of the characteristics, and it was within the measurement error range.

(Comparative Example 1)
In Comparative Example 1, an electrode composed of only a TiN layer was formed on the surface of the low thermal expansion ceramic material 11 by the same method as in Example 1. Then, when it was going to peel off the mask used when forming an electrode, the electrode also peeled off in this case. This is because the internal stress of the TiN layer is not sufficiently relaxed, and the adhesion with the low thermal expansion ceramic material 11 is insufficient. Since the electrodes were peeled off in this way, the same electrostatic adsorption force and leakage current measurement as in Example 1 could not be performed.

(Comparative Example 2)
In Comparative Example 2, a groove having a depth of 45 μm was dug in a portion of the low thermal expansion ceramic substrate 2 where an electrode was to be formed, and a 50 μm W mesh sheet processed into an electrode shape was placed therein. And the low thermal expansion ceramics 11 and the low thermal expansion ceramic base | substrate 2 were joined by the hot press similar to Example 1. FIG.

  And the test similar to Example 1 was done. As a result, as shown in FIG. 4, unlike Examples 1-12, the initial characteristics of the electrostatic chuck were good and could be used stably up to 200 hours, but when used up to 400 hours In addition, the occurrence of cracks in the dielectric portion was observed. Furthermore, the measurement was stopped because the leakage current increased.

It is sectional drawing which shows the low thermal expansion ceramic member which concerns on embodiment of this invention. It is a figure which shows the electrode pattern. It is a figure which shows the conditions of an Example and a comparative example. It is a figure which shows the result of an Example and a comparative example.

Explanation of symbols

1: Dielectric part 2: Low thermal expansion ceramic substrate 3: Electrode 4: Groove 11: Low thermal expansion ceramic material 12: Electrode pattern

Claims (17)

A low thermal expansion ceramic substrate;
An electrode provided on the low thermal expansion ceramic substrate;
A low thermal expansion ceramic dielectric part covering the electrode;
Have
The structure of the electrode is:
A first layer composed of a nitride or composite nitride of group IVa element of the periodic table, a nitride or composite nitride of group Va element of the periodic table, or a nitride or composite nitride of group VIa element of the periodic table;
A second layer comprising a periodic table IVa, Va or VIa group element;
A low thermal expansion ceramic member characterized by having a laminated structure of The first layer is made of Ti nitride or composite nitride,
The low thermal expansion ceramic member according to claim 1, wherein the second layer is made of Ti. The first layer is made of Cr nitride or composite nitride,
The low thermal expansion ceramic member according to claim 1, wherein the second layer is made of Cr.   4. The low thermal expansion ceramic member according to claim 1, wherein the electrode has a thickness of 3 μm or more. 5. The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic base are:
MgO: 8 to 17.2% by mass,
Al ₂ O ₃ : 22 to 38% by mass,
SiO ₂ : 49.5 to 70% by mass, and Li ₂ O: 0.1 to 2.5% by mass,
5. The low thermal expansion ceramic member according to claim 1, comprising: The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic base further contain one or more transition metal compounds excluding Ti (as oxides): 0.1 to 2% by mass,
The mass of SiO ₂ [SiO _2],
The mass of the LiO ₂ [LiO _2],
The mass of MgO is [MgO],
The mass of the _{Al 2 O 3 [Al 2 O} 3]
When
([SiO ₂ ] -8 × [Li ₂ O]) / [MgO] ≧ 3 and ([SiO ₂ ] −8 × [Li ₂ O]) / [Al ₂ O ₃ ] ≧ 1.2 The low thermal expansion ceramic member according to claim 5, wherein the relationship is satisfied.   The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic base further contain one or more rare earth element compounds (oxide conversion): 10% by mass or less. 2. A low thermal expansion ceramic member according to 1. The low thermal expansion ceramic dielectric part and the low thermal expansion ceramic substrate further include:
8. The composition according to claim 5, comprising at least one selected from the group consisting of a Ti compound (in terms of TiO ₂ ): 1% by mass or less, and C: 5% by mass or less. Low thermal expansion ceramic member. Forming an electrode on the first low thermal expansion ceramic material;
Sandwiching the electrode between the first and second low thermal expansion ceramic materials by bonding a second low thermal expansion ceramic material to the first low thermal expansion ceramic materials;
Have
As the electrode,
A first layer composed of a nitride or composite nitride of group IVa element of the periodic table, a nitride or composite nitride of group Va element of the periodic table, or a nitride or composite nitride of group VIa element of the periodic table;
A second layer comprising a periodic table IVa, Va or VIa group element;
A method for producing a low thermal expansion ceramic member, characterized in that a member having a multilayer structure is formed. As the first layer, formed of Ti nitride or composite nitride,
The method for producing a low thermal expansion ceramic member according to claim 9, wherein the second layer is made of Ti. As the first layer, a layer made of Cr nitride or composite nitride is formed,
The method for producing a low thermal expansion ceramic member according to claim 9, wherein the second layer is made of Cr.   The method for producing a low thermal expansion ceramic member according to any one of claims 9 to 11, wherein a thickness of the electrode is 3 µm or more. As the first and second low thermal expansion ceramic materials,
MgO: 8 to 17.2% by mass,
Al ₂ O ₃ : 22 to 38% by mass,
SiO ₂ : 49.5 to 70% by mass, and Li ₂ O: 0.1 to 2.5% by mass,
The method for producing a low thermal expansion ceramic member according to any one of claims 9 to 12, wherein a material containing a low thermal expansion ceramic member is used. As the first and second low thermal expansion ceramic materials,
Furthermore, 1 type or 2 types or more of transition metals except Ti (oxide conversion): 0.1-2 mass% is contained,
The mass of SiO ₂ [SiO _2],
The mass of the LiO ₂ [LiO _2],
The mass of MgO is [MgO],
The mass of the _{Al 2 O 3 [Al 2 O} 3]
When
([SiO ₂ ] -8 × [Li ₂ O]) / [MgO] ≧ 3 and ([SiO ₂ ] −8 × [Li ₂ O]) / [Al ₂ O ₃ ] ≧ 1.2 The method for producing a low thermal expansion ceramic member according to claim 13, wherein a material satisfying the relationship is used.   The first and second low-thermal-expansion ceramic materials further include one or more rare earth element compounds (as oxides): those containing 10% by mass or less. 15. A method for producing a low thermal expansion ceramic member according to 13 or 14. As the first and second low thermal expansion ceramic materials,
The compound containing at least one selected from the group consisting of a Ti compound (in terms of TiO ₂ ): 1% by mass or less and C: 5% by mass or less is used. 2. A method for producing a low thermal expansion ceramic member according to item 1.   The method for producing a low thermal expansion ceramic member according to any one of claims 9 to 16, wherein the first and second layers are formed by physical vapor deposition.

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