Patent Application
20240404862
This application claims priority from Japanese Patent Application No. 2023-092635, filed on Jun. 5, 2023, the entire content of which is incorporated herein by reference.
The present invention relates to a ceramic substrate, a method of manufacturing the same, an electrostatic chuck, a substrate fixing device, and a semiconductor device package.
In the related art, a film forming apparatus or a plasma etching apparatus used for manufacturing a semiconductor device includes a stage for accurately holding a wafer in a vacuum processing chamber. As the stage, for example, a substrate fixing device that suctions and holds a wafer by an electrostatic chuck mounted on a base plate has been proposed.
The electrostatic chuck is formed of a ceramic substrate having a base, an electrostatic electrode incorporated in the base, or the like. The electrostatic electrode is, for example, a sintered body containing tungsten as a main component, nickel oxide, aluminum oxide, and silicon dioxide.
In the above sintered body, a ceramic and tungsten are sintered under the same conditions, but since tungsten has a high melting point (3300° C. or higher), it is difficult to sinter the sintered body, and it is necessary to add an appropriate sintering aid. In the above sintered body, nickel oxide, aluminum oxide, and silicon dioxide function as the sintering aid (for example, see JP2020-043336A).
Some materials that function as the sintering aid for sintering tungsten are relatively difficult to obtain. Therefore, the number of selections of the materials functioning as the sintering aid is preferably large, and a new sintering aid for sintering tungsten is required.
The present invention has been made in view of the above points, and an object thereof is to provide a ceramic substrate in which a conductor pattern containing tungsten is sintered using a sintering aid different from one in the related art.
According to an aspect of the present disclosure, there is provided a ceramic substrate includes a base, and a conductor pattern incorporated in the base. The base is a ceramic, and the conductor pattern includes, as a main component, a solid solution of a body-centered cubic lattice structure in which nickel and manganese are solid solved in tungsten, a solid solution of a body-centered cubic lattice structure in which nickel and niobium are solid solved in tungsten, or a solid solution of a body-centered cubic lattice structure in which nickel and indium are solid solved in tungsten.
According to the disclosed technique, it is possible to provide the ceramic substrate in which the conductor pattern containing tungsten is sintered using a sintering aid different from one in the related art.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description thereof may be omitted.
The base plate 10 is a member for mounting the electrostatic chuck 20. The thickness of the base plate 10 is, for example, about 20 to 40 mm. The base plate 10 is formed of, for example, a metal material such as aluminum or a super hard alloy, a composite material of the metal material and a ceramic material, or the like, and can be used as an electrode or the like for controlling plasma. For example, in terms of availability, ease of processing, good thermal conductivity, or the like, it is preferable to use aluminum or an alloy thereof and to perform an alumite treatment (insulating layer formation) on a surface thereof.
For example, by supplying a predetermined high frequency power to the base plate 10, it is possible to control energy for causing generated ions or the like in a plasma state to collide with the substrate W suctioned on the electrostatic chuck 20, and to effectively perform etching processing.
A gas supply passage for introducing an inert gas for cooling the substrate W suctioned on the electrostatic chuck 20 may be provided inside the base plate 10. When an inert gas such as He or Ar is introduced into the gas supply passage from the outside of the substrate fixing device 1 and the inert gas is supplied to a back surface of the substrate W suctioned on the electrostatic chuck 20, the substrate W can be cooled.
A coolant flow path may be provided inside the base plate 10. The coolant flow path is, for example, an annular hole formed inside the base plate 10. A coolant such as cooling water or Galden is introduced into the coolant flow path from the outside of the substrate fixing device 1. By circulating the coolant through the coolant flow path to cool the base plate 10, the substrate W suctioned on the electrostatic chuck 20 can be cooled.
The electrostatic chuck 20 is a portion that suctions and holds the substrate W which is a suction target object. A planar shape of the electrostatic chuck 20 is formed according to a shape of the substrate W, and is, for example, circular. A diameter of the wafer which is the suction target object by the electrostatic chuck 20 is, for example, 8, 12, or 18 inches.
The “planar view” refers to a view of an object from a direction normal to an upper surface 10a of the base plate 10, and the “planar shape” refers to a shape of the object viewed from the direction normal to the upper surface 10a of the base plate 10.
The electrostatic chuck 20 is provided on the upper surface 10a of the base plate 10 via an adhesive layer. The adhesive layer is, for example, a silicone-based adhesive. A thickness of the adhesive layer is, for example, about 0.1 to 2.0 mm. The adhesive layer adheres to the base plate 10 and the electrostatic chuck 20, and has an effect of reducing stress caused by a difference in thermal expansion coefficient between the electrostatic chuck 20 made of a ceramic and the base plate 10 made of aluminum. The electrostatic chuck 20 may be fixed to the base plate 10 by screws.
The electrostatic chuck 20 is a ceramic substrate having a base body 21, an electrostatic electrode 22, and a heating element 24 as main components. An upper surface of the base 21 is a placement surface 21a on which the suction target object is placed. The electrostatic chuck 20 is, for example, a Johnsen-Rahbek type electrostatic chuck. However, the electrostatic chuck 20 may be a Coulomb force type electrostatic chuck.
The base 21 is a dielectric. The thickness of the base 21 is, for example, about 5 to 10 mm, and a relative dielectric constant (1 kHz) of the base 21 is, for example, about 9 to 10. The base 21 preferably has an insulation resistivity of 1014 Ωcm or more at 300° C.
The base 21 is, for example, a ceramic containing aluminum oxide (Al2O3) or yttrium aluminum garnet (YAG) as a main component.
The base 21 is preferably an aluminum oxide ceramic containing an yttrium aluminum garnet phase (YAG phase) by 10 mol % or more and 80 mol % or less. Accordingly, the insulation resistivity of the base 21 at 300° C. can be 1014 Ωcm or more at 300° C.
The base 21 may be an aluminum oxide ceramic having a purity of aluminum oxide of 99 wt % or more. Accordingly, the insulation resistivity of the base 21 at 300° C. can be 1014 Ωcm or more at 300° C. The purity of 99% or more indicates that the base 21 is formed without adding a sintering aid. In addition, the purity of 99% or more means that unintended impurities may be contained in a manufacturing process or the like. The base 21 preferably has a relative density of 97% or more with respect to aluminum oxide. In the base 21, an average particle diameter of aluminum oxide is preferably 1.0 μm or less in order to improve sinterability.
The electrostatic electrode 22 is a thin-film electrode formed of a conductor pattern, and is incorporated in the base 21. In the present embodiment, the electrostatic electrode 22 is of a bipolar type and includes a first electrostatic electrode 22a and a second electrostatic electrode 22b. As the electrostatic electrode 22, a unipolar type including one electrostatic electrode may be used.
A main component of the electrostatic electrode 22 is, for example, a solid solution having a body-centered cubic lattice structure in which nickel and manganese are solid solved in tungsten. A main component of the electrostatic electrode 22 may be a solid solution having a body-centered cubic lattice structure in which nickel and niobium are solid solved in tungsten. The main component of the electrostatic electrode 22 may be a solid solution having a body-centered cubic lattice structure in which nickel and indium are solid solved in tungsten.
The main component of the electrostatic electrode 22 may be a solid solution having a body-centered cubic lattice structure in which nickel, manganese, and a predetermined element are solid solved in tungsten. The predetermined element in this case is boron, magnesium, scandium, vanadium, chromium, iron, zinc, gallium, germanium, strontium, zirconium, niobium, molybdenum, or barium.
The main component of the electrostatic electrode 22 may be a solid solution having a body-centered cubic lattice structure in which nickel, niobium, and a predetermined element are solid solved in tungsten. The predetermined element in this case is boron, magnesium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, zinc, gallium, germanium, strontium, zirconium, molybdenum, indium, or barium.
The main component of the electrostatic electrode 22 may be a solid solution having a body-centered cubic lattice structure in which nickel, indium, and a predetermined element are solid solved in tungsten. The predetermined element in this case is magnesium, calcium, scandium, titanium, vanadium, chromium, zinc, gallium, germanium, strontium, zirconium, niobium, molybdenum, or barium.
Here, the main component means a component occupying 50 wt % or more of all substances constituting the electrostatic electrode 22. In the electrostatic electrode 22, the ratio of nickel and manganese to tungsten is preferably 0.05 wt % or more and 10 wt % or less. The same applies to the cases of nickel and niobium, or nickel and indium, and the ratio of each to tungsten is preferably 0.05 wt % or more and 10 wt % or less. The ratio of the predetermined element described above to tungsten is preferably 0.05 wt % or more and 10 wt % or less.
The first electrostatic electrode 22a is connected to a positive electrode side of a power supply 40a provided outside the substrate fixing device 1. The second electrostatic electrode 22b is connected to a negative electrode side of a power supply 40b provided outside the substrate fixing device 1. The negative electrode side of the power supply 40a and the positive electrode side of the power supply 40b are connected outside the substrate fixing device 1, and a connection point is a ground potential.
A positive (+) voltage is applied from the power supply 40a to the first electrostatic electrode 22a, and a negative (−) voltage is applied from the power supply 40b to the second electrostatic electrode 22b. Accordingly, the first electrostatic electrode 22a is charged with the positive (+) charge, and the second electrostatic electrode 22b is charged with the negative (−) charge. Accordingly, the negative (−) charge is induced in a portion Wa of the substrate W corresponding to the first electrostatic electrode 22a, and the positive (+) charge is induced in a portion Wb of the substrate W corresponding to the second electrostatic electrode 22b.
When the substrate W, the electrostatic electrode 22, and a ceramic portion 25 of the electrostatic chuck 20 (base 21) disposed therebetween are regarded as capacitors, the ceramic portion 25 corresponds to a dielectric layer. Then, the substrate W is electrostatically sucked onto the electrostatic chuck 20 by Coulomb force generated between the electrostatic electrode 22 and the substrate W via the ceramic portion 25. A suction-holding force increases as the voltage applied to the electrostatic electrode 22 increases.
The heating element 24 is a heater that is incorporated in the base 21 and generates heat when a current flows to heat the placement surface 21a of the base 21 to a predetermined temperature. The heating element 24 is disposed below (at a base plate 10 side of) the first electrostatic electrode 22a and the second electrostatic electrode 22b. The heating element 24 is a conductor formed in a film shape. The heating element 24 is provided as a plurality of heater electrodes capable of independently controlling heating of a plurality of regions (heater zones) of the base 21 in a plane. The heating element 24 may be provided as one heater electrode. The heating element 24 can be formed of, for example, a material similar to that of the electrostatic electrode 22.
When a current is supplied to the heating element 24 from a power supply provided outside the substrate fixing device 1, the heating element 24 generates heat to heat the electrostatic chuck 20. The substrate W is controlled to a predetermined temperature by the temperature of the electrostatic chuck 20. A heating temperature of the electrostatic chuck 20 is set within a range of 50° C. to 200° C., for example, 150° C.
Further, the electrostatic chuck 20 and the base plate 10 have a plurality of (three in
Next, a method of manufacturing the electrostatic chuck 20 will be described.
First, as shown in
Next, as shown in
For forming the conductor pattern 55, a conductive paste obtained by adding nickel oxide and manganese oxide to tungsten, a conductive paste obtained by adding nickel oxide and niobium oxide to tungsten, or a conductive paste obtained by adding nickel oxide and indium oxide to tungsten is used. The conductive paste used for forming the conductor pattern 55 may further contain the predetermined element described above. The conductive paste used for forming the conductor pattern 55 may further contain an organic material or the like.
An addition amount of nickel oxide and manganese oxide is, for example, preferably 0.1 g or more and 10 g or less with respect to 100 g of tungsten. That is, in the conductive paste, the ratio of nickel oxide and manganese oxide to tungsten is preferably 0.1 wt % or more and 10 wt % or less. When the ratio of nickel oxide and manganese oxide to tungsten is 0.1 wt % or more, a liquid phase formation temperature of the conductive paste can be 1450° C. or less. The similarity applies to nickel oxide and niobium oxide, and nickel oxide and indium oxide, and the ratio of each to tungsten is preferably 0.1 wt % or more and 10 wt % or less.
Even if the ratio of nickel oxide and manganese oxide, nickel oxide and niobium oxide, or nickel oxide and indium oxide to tungsten is more than 10 wt %, the liquid phase formation temperature of the conductive paste is still 1450° C. or less. However, when the ratio of nickel oxide and manganese oxide, nickel oxide and niobium oxide, or nickel oxide and indium oxide to tungsten is more than 10 wt %, electrical characteristics of tungsten are less likely to be exhibited in a solid solution containing tungsten produced by sintering the conductive paste. Therefore, the ratio of nickel oxide and manganese oxide, nickel oxide and niobium oxide, or nickel oxide and indium oxide to tungsten is preferably 10 wt % or less. When the conductive paste and the green sheet are fired simultaneously, an average particle size of tungsten is preferably 0.5 μm or more and 3.0 μm or less.
Next, as shown in
Next, as shown in
Next, the structure 71b shown in
It should be noted that tungsten is sintered in a temperature range from the liquid phase formation temperature of the conductive paste to the temperature (for example, 1600° C.) at which the ceramic substrate 72a is fired, and if this temperature range is narrow, tungsten cannot be sufficiently sintered. The liquid phase formation temperature is preferably 1450° C. or lower. When the liquid phase formation temperature is 1450° C. or lower, tungsten can be sufficiently sintered.
On the other hand, the liquid phase formation temperature of the conductive paste should not be too low. When the temperature range from the liquid phase formation temperature to the temperature (for example, 1600° C.) at the time of firing the ceramic substrate 72a is widened, the probability that tungsten is burned too much to cause excessive sintering increases. When tungsten is excessively sintered, adhesion to the ceramic is reduced. The liquid phase formation temperature is preferably 1390° C. or higher. When the liquid phase formation temperature is 1390° C. or higher, the probability of excessive sintering of tungsten can be reduced.
Next, various processes are performed on the ceramic substrate 72a to complete the electrostatic chuck 20. For example, upper and lower surfaces of the ceramic substrate 72a are polished to form the placement surface and an adhering surface. The lift pin openings 12 shown in
Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In Example 1, 1 g of nickel oxide and 1 g of manganese oxide were added to 100 g of tungsten, and a liquid phase formation temperature in a case where an adjustment was performed in an atmosphere of nitrogen and hydrogen was calculated by Fact Sage (manufactured by Research Center of Computational Mechanics, Inc). Fact Sage is software for quantitatively predicting a thermodynamic equilibrium state of a multi-component system.
Calculation results of Example 1 are shown in
Next, in Example 2, 1 g of nickel oxide and 1 g of niobium oxide were added to 100 g of tungsten, and a liquid phase formation temperature in a case where an adjustment was performed in an atmosphere of nitrogen and hydrogen was calculated by Fact Sage.
Calculation results of Example 2 are shown in
Next, in Example 3, 1 g of nickel oxide and 1 g of indium oxide were added to 100 g of tungsten, and a liquid phase formation temperature when an adjustment was performed in an atmosphere of nitrogen and hydrogen was calculated by Fact Sage.
Calculation results of Example 3 are shown in
As described above, when the nickel oxide and the manganese oxide, the nickel oxide and the niobium oxide, or the nickel oxide and the indium oxide are added to tungsten and fired, the liquid phase formation temperature can be about 1430° C. to 1450° C. Since this temperature is sufficiently lower than the melting point (3300° C. or higher) of tungsten and lower than the sintering temperature (for example, about 1500° C. to 1600° C.) of the base, tungsten can be easily sintered.
That is, the nickel oxide and the manganese oxide, the nickel oxide and the niobium oxide, and the nickel oxide and the indium oxide are useful as a sintering aid different from a sintering aid of the related art used in sintering a conductor pattern containing tungsten in a ceramic substrate.
Next, as Example 4, a predetermined element was further added to Examples 1 to 3, and the liquid phase formation temperature when an adjustment was performed in an atmosphere of nitrogen and hydrogen was calculated by Fact Sage.
For example, when 1 g of nickel oxide, 1 g of manganese oxide, and 1 g of boron oxide were added to 100 g of tungsten, and an adjustment was performed in an atmosphere of nitrogen and hydrogen, a liquid phase formation temperature was calculated by Fact Sage, and the liquid phase formation temperature was about 1410° C.
When 1 g of nickel oxide, 1 g of niobium oxide, and 1 g of iron oxide were added to 100 g of tungsten, and adjustment was performed in an atmosphere of nitrogen and hydrogen, the liquid phase formation temperature was calculated from Fact Sage, and the liquid phase formation temperature was about 1420° C.
When 1 g of nickel oxide, 1 g of indium oxide, and 1 g of gallium oxide were added to 100 g of tungsten, and an adjustment was performed in an atmosphere of nitrogen and hydrogen, the liquid phase formation temperature was calculated by Fact Sage, and the liquid phase formation temperature was about 1410° C.
When 1 g of nickel oxide, 1 g of niobium oxide, and 1 g of indium oxide were added to 100 g of tungsten, and adjustment was performed in an atmosphere of nitrogen and hydrogen, the liquid phase formation temperature was calculated by Fact Sage, and the liquid phase formation temperature was about 1390° C.
As shown in a region surrounded by a coarse broken line in
Further, as shown in a region surrounded by a solid line in
Further, as shown in a region surrounded by a fine broken line in
In particular, when nickel oxide, niobium oxide, and indium oxide are added to tungsten, the liquid phase formation temperature can be set to about 1390° C., which is effective for lowering the liquid phase formation temperature.
In a second embodiment, an example of a semiconductor device package having the ceramic substrate described in the first embodiment will be described.
As shown in
The ceramic substrate 110 includes a plurality of (four in the present embodiment) stacked ceramic base materials 111, 112, 113, and 114, wiring patterns 121, 122, 123, and 124 as an example of the conductor pattern, and vias 132, 133, and 134 penetrating the ceramic base materials 112, 113, and 114. The via 132 connects the wiring patterns 121 and 122 to each other, the via 133 connects the wiring patterns 122 and 123 to each other, and the via 134 connects the wiring patterns 123 and 124 to each other. In the ceramic substrate 110, the ceramic base materials 111 to 114 constitute a base.
As shown in
The ceramic base materials 111 to 114 are ceramics made of aluminum oxide, and the wiring patterns 121 to 124 include, as a main component, a solid solution of a body-centered cubic lattice structure in which nickel and manganese are solid solved in tungsten, a solid solution of a body-centered cubic lattice structure in which nickel and niobium are solid solved in tungsten, and a solid solution of a body-centered cubic lattice structure in which nickel and indium are solid solved in tungsten. The wiring patterns 121 to 124 may further contain the predetermined element described above. The vias 132 to 134 are, for example, sintered bodies containing molybdenum as a main component, nickel oxide, aluminum oxide, and silicon dioxide. The ceramic substrate 110 can be manufactured by a method similar to the method of manufacturing the electrostatic chuck 20 of the first embodiment.
In the semiconductor device package 100, the semiconductor element 200 is mounted on the heat sink 150. The pad of the semiconductor element 200 is electrically connected to the wiring pattern 121 of the ceramic substrate 110 by a bonding wire or the like. Accordingly, the semiconductor element 200 is connected to the external connection terminals 160 through the wiring patterns 121 to 124 and the vias 132 to 134.
In the semiconductor device package 100, the wiring patterns 121 to 124 can be formed by sintering a conductive paste obtained by adding nickel oxide and manganese oxide to tungsten, a conductive paste obtained by adding nickel oxide and niobium oxide to tungsten, or a conductive paste obtained by adding nickel oxide and indium oxide to tungsten. The conductive paste may further contain the predetermined element described above. Accordingly, tungsten can be easily sintered as in the first embodiment.
Although the preferred embodiments and the like have been described in detail, the present invention is not limited to the embodiments and the like described above, and various modifications and substitutions can be made to the embodiments and the like described above without departing from the scope of the claims.
For example, in the first embodiment, the members and arrangement provided in the substrate fixing device may be appropriately changed.
In the first embodiment, the heating element 24 may be disposed between the electrostatic chuck 20 and the base plate 10. The heating element 24 may be provided inside the base plate 10. Further, the heating element 24 may be externally attached to a lower side of the electrostatic chuck 20.
The substrate fixing device according to the first embodiment is applied to the semiconductor manufacturing device, for example, a dry etching device (for example, a parallel plate type reactive ion etching (RIE) device).
Further, as the suction target object of the substrate fixing device according to the first embodiment, a glass substrate or the like used in a manufacturing process of a liquid crystal panel or the like may be exemplified in addition to the semiconductor wafer (silicon wafer or the like).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-092635 | Jun 2023 | JP | national |
