Patent Application
20120329290
This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Japanese Patent Application No. 2011-117723 filed on May 26, 2011 and Japanese Patent Application No. 2012-107668 and May 9, 2012, in the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a substrate processing apparatus for manufacturing a semiconductor integrated circuit device (hereinafter referred to as an IC) and the like. In particular, the present invention relates to a substrate placement stage, a substrate processing apparatus using the same, and a method of manufacturing a semiconductor device using the substrate processing apparatus, capable of suppressing thermal deformation of the substrate placement stage when the substrate placement stage on which the substrate is placed is heated in a process chamber in the substrate processing apparatus including the process chamber configured to process a semiconductor substrate (for example, a semiconductor wafer) on which a semiconductor integrated circuit is manufactured.
2. Description of the Related Art
In the related art, as disclosed in Japanese Patent Unexamined Application No. 2009-88347, it has been known that a substrate processing apparatus in which a heater is housed in a substrate placement stage on which a substrate is placed in a process chamber and the substrate is heated and processed by the heater. Since the substrate placement stage is mainly made of aluminum, such a substrate processing apparatus is usually used at a temperature equal to or less than about 400° C. in order to avoid thermal deformation in consideration of thermal resistance of the substrate placement stage. As the thermal deformation of the substrate placement stage is suppressed, the substrate placed on the substrate placement stage can be uniformly heated.
In recent years, a need for a substrate to be processed uniformly at a high temperature has arisen. To achieve this, for example, a pure aluminum-based alloy with low impurities may be used as a material of the substrate placement stage. However, when the pure aluminum-based alloy with low impurities is set to a high temperature, crystallization of the aluminum progresses on a surface of the substrate placement stage, such that wrinkle-like concave and convex portions are generated. Since variation in distance between the substrate placed on the surface of the substrate placement stage and the heater occurs due to the concave and convex portions, the substrate cannot be heated uniformly.
In addition, an A5052 aluminum alloy having high temperature resistance may be used as a material of the substrate placement stage. However, since the A5052 aluminum alloy contains magnesium (Mg), if the substrate placement stage is high-temperature condition, the magnesium (Mg) is oxidized, and the surface of the substrate placement stage may be discolored at a high temperature. When the surface is discolored, since an emission rate of heat rays emitted from the heater is changed, the heater does not raise the temperature of the substrate up to a desired temperature.
To allow the substrate to be processed at higher temperature, the substrate placement stage may be made of materials such as stainless steel or aluminum nitride (AlN). However, since these materials have a low thermal conductivity compared to aluminum, temperature uniformity is lowered when the substrate is heated. In addition, these materials may also contribute to an increase in total weight of the substrate placement stage or cost.
It is an object of the present invention to provide a substrate placement stage or a substrate processing apparatus, or a method of manufacturing the substrate placement stage or a method of manufacturing a semiconductor device in which, when the substrate placement stage on which a substrate is placed is heated in a process chamber, the substrate can be set to a high temperature and can be uniformly heated.
According to one aspect of the present invention, there is provided a substrate placement stage including: a heating element; a first member surrounding the heating element; and a second member covering a surface of the first member and including a placing surface for placing a substrate thereon, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material containing ceramics and aluminum, a content of the ceramics in the second material being lower than that of the first material.
According to another aspect of the present invention, there is provided a substrate processing apparatus including: a process chamber configured to process a substrate; a gas supply unit configured to supply a processing gas into the process chamber; a gas exhaust unit configured to exhaust the processing gas from an inside of the process chamber; and a substrate placement stage installed in the inside of the process chamber, the substrate placement stage including: a heating element; a first member surrounding the heating element; and a second member covering a surface of the first member, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material containing ceramics and aluminum, a content of the ceramics in the second material being lower than that of the first material.
According to still another aspect of the present invention, there is provided a method of manufacturing a semiconductor device using a substrate processing apparatus including: a process chamber configured to process a substrate; a gas supply unit configured to supply a processing gas into the process chamber; a gas exhaust unit configured to exhaust the processing gas from an inside of the process chamber; and a substrate placement stage installed in the inside of the process chamber including: a heating element; a first member surrounding the heating element; and a second member covering a surface of the first member, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material containing ceramics and aluminum, a content of the ceramics in the second material being lower than that of the first material, the method including: loading the substrate into the process chamber and placing the substrate on the substrate placement stage; heating the substrate using the heating element; supplying the processing gas into the process chamber using the gas supply unit; exhausting the processing gas from the process chamber using the gas exhaust unit; and unloading the substrate from the inside of the process chamber.
According to the configuration, when a substrate placed on a substrate placement stage is heated in a process chamber, the substrate can be uniformly heated
In the embodiment of the present invention, as an example, a substrate processing apparatus is configured as a semiconductor manufacturing apparatus performing processing processes in a method of manufacturing a semiconductor device (IC). Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
Meanwhile, the load lock chambers 14a and 14b are disposed at symmetrical positions with respect to each other and have the same configuration. In addition, the process chambers 16a and 16b are also disposed at symmetrical positions with respect to each other and have the same configuration. Hereinafter, the following explanation will focus on the load lock chamber 14a and the process chamber 16a.
As shown in
The vacuum robot 36 which transfers the substrate 22 between the load lock chamber 14a and the process chamber 16a is installed in the transfer chamber 12. The vacuum robot 36 includes an arm 37 having the pair of fingers 38 including an upper finger 38a and a lower finger 38b is installed. The upper finger 38a and the lower finger 38b are configured to have, for example, the same shape, to be spaced at predetermined intervals in the vertical direction, to extend substantially horizontally in the same direction from the arm 37, and to support the substrate 22 at the same time. The arm 37 is configured to rotate about a rotation axis extending in the vertical direction, to be moved in the horizontal direction, and to enable the substrates 22 to be transferred two at a time. Substrate placement stages 44a and 44b are installed in the process chamber 16a within a similar space of a chamber 50 to be described later. A portion of a space between the substrate placement stage 44a and the substrate placement stage 44b is partitioned by a partition member 48 in the horizontal direction. Thereafter, by placing the substrates 22 on the substrate placement stages 44a and 44b through the vacuum robot 36, the process chamber 16a can perform a heat treatment simultaneously on two of the substrates 22 within the same space of the chamber 50.
Next, an overview of the process chamber 16a will be described with reference to
Substrate placement surfaces 46a and 46b which are disposed the substrate placement stages 44a and 44b are provided on surfaces close to the lids 53a and 53b. The heights of both of the substrate placement stages 44a and 44b are lower than that of the inside of the chamber 50, and both of the substrate placement stages 44a and 44b are independently disposed within the same space of the chamber 50 and fixed to the apparatus body 49 through a fixing member 52. In addition, heaters 45a and 45b, which are heating elements, are included, such that the substrate placement stages 44a and 44b can heat the substrates up to about 470° C. The substrate placement stage will be described in detail later.
Flanges 47a and 47b are installed below the substrate placement stages 44a and 44b in a different direction from the substrate placement surfaces 46a and 46b. A plurality of struts 43 fixed to the apparatus body 49 are connected to the flanges 47a and 47b, and the struts 43 support each substrate placement stage 44. A support structure will be described later.
The partition member 48 described above is disposed between the substrate placement stage 44a and the substrate placement stage 44b. The partition member 48 is made of, for example, aluminum (such as A5052 or A5056), quartz, alumina or the like and, for example, is a member having a prismatic shape attachable to the apparatus body 49.
Exhaust baffle rings 54a and 54b, which have ring shapes when viewed from above, are disposed on the substrate placement stages 44a and 44b so as to surround each periphery of thereof. The peripheries of the baffle rings 54a and 54b are provided with a plurality of hole portions 56, to perform exhaust toward a first exhaust space 58 provided around the substrate placement stages 44a and 44b. The hole portions 56 constitute a first exhaust port. In addition, a second exhaust port 60 and a third exhaust port 62, which have ring shapes when viewed from above, are installed below the substrate placement stages 44a and 44b, respectively. In addition, a gas exhaust unit that exhausts gas from the inside of the process chamber mainly includes the first exhaust port 56 or the second exhaust port 60 and the third exhaust port 62.
A robot arm 70, which can transfer the substrate 22, is disposed at one end side of the partition member 48. The robot arm 70 is configured to transfer one of the substrates 22 transferred by the arm 37 described above to the substrate placement stage 44b and to recover the transferred substrate from the substrate placement stage 44b. The robot arm 70 includes a finger 72 [the base of the finger is made of metal in order to match a position and level] made of, for example, alumina ceramics (equal to or greater than 99.6% purity) and a shaft unit 71, and a biaxial driving unit (not shown) that perform rotating and lifting is installed at the shaft unit 71. The finger 72 includes an arcuate portion 72a larger than the substrate 22, and three protruding portions 72b extending toward a center from the arcuate portion 72a are provided at predetermined intervals. When the chamber 50 has been vacuumized, the shaft portion 71 is configured to be blocked from atmosphere through a magnetic seal that is water-cooled. Meanwhile, in order to avoid completely separating the space within the chamber 50, the partition member 48 and the robot arm 70 are disposed inside the chamber 50.
Accordingly, the processing gas supplied through the gas supply units 51a and 51b flows along each substrate 22 placed on the substrate placement stages 44a and 44b within the chamber 50 and is exhausted through a hole portion 56, which is a first exhaust port, the first exhaust space 58, the second exhaust port 60 and the third exhaust port 62.
In addition, in each of the substrate placement stages 44a and 44b, the three substrate holding pins 74 penetrate in the vertical direction, such that the substrate 22 transferred through the vacuum robot 36 from the transfer chamber 12 is placed on the substrate holding pin 74. As shown in
Next, a method of fixing the substrate placement stages 44a and 44b and the strut 43 will be described with reference to
A ring 42 is installed as a fixing unit so as to support a lower portion, which is a periphery of a lower surface of the substrate placement stage 44a, of the flange 47a. The ring 42 has an integral structure of a circular shape and is made of a material that has a low thermal conductivity and is not likely to deform even at a high temperature, for example, stainless steel. The ring 42 is fixed to the lower surface of the substrate placement stage 44a. An insertion port 42a into which the strut 43 is inserted is installed on the ring 42. The strut 43 has a step portion 43a, and the ring 42 is supported by the step portion 43a. A convex portion 43b, which is an upper portion of the strut 43, passes through the insertion port 42a and is fitted in a recess portion provided at the lower portion of the flange 47a. Thus, because the ring 42 supports the substrate placement stage 44a, deformation of the substrate placement stage 44a can be suppressed even at a high temperature state in which the substrate placement stage 44a may be deformed when the substrate is heated by the heater 45a. In addition, a configuration in which the ring 42 does not fix to the lower surface of the substrate placement stage 44a is possible. However, if thermal deformation of the substrate placement stage 44a can be more firmly suppressed, a fixed configuration is also possible. In addition, a side surface of the insertion port 42a is configured so as to be in contact with a side surface of the convex portion 43b of the strut 43. By such a configuration, the strut 43 can be prevented from being tilted.
Next, a structure of the substrate placement stage 44a will be described with reference to
In
The first member 82 is a composite material of at least aluminum and ceramics. In this embodiment, the first member 82 is a composite material of aluminum, silicon and ceramics. A volume ratio of the ceramics in the first member 82 ranges from 20% to 50%. The ceramics are contained in the first member 82, such that thermal expansion can be reduced and thermal deformation can be suppressed, compared to aluminum. In other words, deformation of the placement surface in the substrate placement stage 44a can be prevented. Thus, the substrate placed on the substrate placement stage 44a can receive heat rays generated by the heater 81 with good reproducibility. In addition, the ceramics have a main component of alumina (Al2O3) or silica (SiO2), but the ceramics also include a small amount of sodium (Na). Accordingly, if the sodium leaks into the chamber 50, this can cause metal contamination.
Here, when the proportion of ceramics in the first member 82 is higher, the following problems occur. A first problem is that, when the substrate placement stage 44a is manufactured, injection of the aluminum is difficult if the proportion of the ceramics is high, as will be described later. As a result, the aluminum of a high thermal conductivity is sparsely filled in the ceramics of a low thermal conductivity. In such a case, since a temperature distribution within the substrate placement stage 44a becomes non-uniform, heating uniformity within the surface of the substrate is lowered. In addition, since the temperature distribution within the substrate placement stage 44a is different for each substrate placement stage 44a, heating uniformity between the substrates is lowered. A second problem is that heating efficiency for the substrate is reduced, because the heat emitted from the heater 81 to the substrate is interrupted in fragments. A third problem is that a difference of thermal expansion coefficients of the first member 82 (a composite material of ceramics and aluminum) and second member 83 (an aluminum alloy) is increased. Therefore an interface of the first member 82 and the second member 83 or aluminum ally in the surface of the second member 83 is easily damaged. In consideration of avoiding the above-described problems and suppressing thermal deformation, the percentage of the ceramics in the first member 82 is set between 20% and 50%.
The second member 83 is an alloy of aluminum and silicon in this embodiment. The percentage of silicon is equal to or less than 11.7 wt % which is a eutectic point of silicon. Content of ceramics in the aluminum alloy is smaller than that of the first member 82. The ceramic component in the second member 83 may be 0 (zero). In this way, the surface of the first member 82 is covered with the second member 83, such that metal contamination generated from the first member 82 that contains many ceramics having many impurities (for example, Na) can be suppressed. In addition, as the second member 83 is an aluminum alloy in which the percentage of the silicon is equal to or less than 11.7 wt %, which is a eutectic point of silicon and aluminum, local eduction of silicon can be reduced. When the local eduction of silicon is generated, spots appear on the surface. Thus, the temperature distribution in the substrate placement stage 44a becomes non-uniform, and heating uniformity in the surface of the substrate is lowered. In addition, in consideration of ease of casting or improving strength, the second member 83 may be made of an aluminum alloy of which the percentage of silicon is 4.0 wt % or more. A rate of thermal expansion of the aluminum alloy being the second member 83 is greater than that of the composite material being the first member 82. In order to minimize the effects due to the difference in thermal expansion between the first member 82 and the second member 83, it is desirable to reduce a thickness of the second member 83. However, because there is a need to consider workability, which will be described later, the thickness of the second member 83 is set between 2 mm and 10 mm.
As mentioned in the description of
Next, a method of manufacturing the substrate placement stage 44a will be described with reference to
Next, as shown in
By the method described above, the substrate placement stage in which temperature uniformity and economic efficiency are excellent can be easily achieved, and the substrate placement stage can be heated up to a temperature of, for example, 470° C. The substrate placement stage has a periphery of the heater which is covered with the first member, which is a composite material of ceramics and aluminum, and a periphery of the first member which is covered with the second member. The second member is an aluminum alloy of which the percentage of silicon is equal to or less than 11.7 wt %, which is a eutectic point of silicon and aluminum. When a temperature cycle test was performed in the substrate placement stage manufactured according to the method, occurrence of discoloration or wrinkles seen in the substrate placement stage of the aluminum alloy of the related art was not observed. In the temperature cycle test, by repeating a cycle in which the temperature was raised to 450° C., lowered to 200° C. and raised to 400° C. again, the cycle of 450° C.→200° C.→450° C. was performed 40 times.
Next, an operation of transferring the substrate 22 by the robot arm 70, and a substrate processing method will be described as a process of the method of manufacturing a semiconductor device according to the embodiment of the present invention with reference to
Then, in a state in which the pair of fingers 38 are stopped, the three substrate holding pins 74 penetrating the substrate placement stage 44a and the robot arm 70 are moved upward. Here, the substrate 22 placed on the lower finger 38b is transferred to the three substrate holding pins 74 penetrating the substrate placement stage 44a, and the substrate 22 placed on the upper finger 38a is transferred to the finger 72. The pair of fingers 38 transferring the two substrates 22 is returned to the transfer chamber 12.
Then, as shown in
Then, the finger 72 of the robot arm 70 is moved below the substrate placement surface 46b. When the finger 72 of the robot arm 70 is moved downward, the three substrate holding pins 74 penetrating the substrate placement stage 44a and the three substrate holding pins 74 penetrating the substrate placement stage 44b are moved downward, the substrate 22 transferred by the lower finger 38b and the substrate 22 transferred by the upper finger 38a are placed on the substrate placement surfaces 46a and 46b, respectively, at substantially the same time. In addition, in a state in which gas supplied from the gas supply units 51a and 51b is not inhibited from flowing downward from above, the robot arm 70 is located within the chamber 50 during the processing of the substrate 22.
The substrates 22 placed on the substrate placement surfaces 46a and 46b are heated to a desired temperature, for example, 470° C., by the heaters 45a and 45b. In parallel with the heating processing, a processing gas is supplied from the gas supply units 51a and 51b. For example, nitrogen (N2) gas is supplied as the processing gas. In an atmosphere of the supplied processing gas, the substrates 22 are heated, and a predetermined heat treatment is performed.
When the predetermined heat treatment is finished, the processing gas is exhausted from the inside of the chamber 50. Then, the two substrates 22 are transferred from the inside of the chamber 50 to the transfer chamber 12. In this case, the robot arm 70 and the pair of fingers 38 perform operations in the reverse order of the operations described with reference to
According to the embodiment described above, at least the following effects (1) to (7) may be obtained.
(1) When the substrate placement stage on which the substrate is placed is heated in the process chamber, since thermal deformation of the substrate placement stage can be suppressed by ceramics in the first member, the substrate can be heated with good reproducibility. In addition, metal contamination due to ceramics in the first member can be suppressed by the second member.
(2) Since the second member is made of a mixed material of ceramics and aluminum, a change in emission rate due to surface discoloration and occurrence of wrinkles due to crystallization can be suppressed. In addition, since deformation of the substrate placement stage can be suppressed, the substrate can be heated with good reproducibility.
(3) Since the percentage of the silicon of the second member is equal to or less than 11.7 wt %, which is a eutectic point of silicon and aluminum, local eduction of silicon can be suppressed.
(4) Since the thickness of the second member is set between 2 mm and 10 mm, the effects due to the difference of thermal expansion between the first member and the second member can be reduced and good workability can be obtained.
(5) Since at least the periphery of the lower surface of the first member or the second member can be supported by stainless steel, which is the third member having lower thermal deformation than the first member or the second member, thermal deformation of the first member or the second member can be further suppressed.
(6) Since at least the periphery of the lower surface of the first member or the second member can be supported by stainless steel, which is the third member having a lower thermal conductivity than the first member or the second member, local thermal leakage can be suppressed through the third member, and the substrate can be uniformly heated.
(7) By the method of manufacturing the substrate placement stage described above, the substrate placement stage in which the periphery of the heating element is covered with the first member, which is a composite material of ceramics and aluminum, the periphery of the first member is covered with the second member, and the content of the ceramics component is less than that of the first member 82 can be easily achieved.
In addition, it is obvious that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the scope of the present invention. In the embodiments described above, the second member is configured to surround the first member, but the second member may be configured so as to cover only a part of the substrate placement stage exposed to the processing gas supplied into the process chamber. By such a configuration, the suppression of metal contamination is slightly lowered, compared to the embodiment described above, but the substrate placement stage can be easily manufactured. In addition, in the above-described embodiments, a process performed on substrates such as wafers has been described. However, objects to be processed may be a hot mask or printed wiring substrate, an LED panel, a compact disc or a magnetic disk, etc.
This specification includes at least the following inventions.
The first invention relates to a substrate placement stage including: a heating element; a first member configured to surround the heating element; and a second member configured to cover a surface of the first member and including a placing surface for placing a substrate on one surface thereof, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material in which a content of the ceramics is lower than that of the first material and the ceramics and aluminum are contained.
As the second invention, in the substrate placement stage described in the first invention, the second member is made of a mixed material of silicon and aluminum.
As the third invention, in the substrate placement stage described in the second invention, a percentage of the silicon of the second member is equal to or less than 11.7 wt %, which is a eutectic point of silicon and aluminum
The fourth invention relates to a substrate processing apparatus including: a process chamber configured to process a substrate; a gas supply unit configured to supply a processing gas into the process chamber; a gas exhaust unit configured to exhaust the processing gas from an inside of the process chamber; and a substrate placement stage installed in the inside of the process chamber, the substrate placement stage including: a heating element; a first member surrounding the heating element; and a second member covering a surface of the first member, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material containing ceramics and aluminum, a content of the ceramics in the second material being lower than that of the first material.
As the fifth invention, in the substrate processing apparatus described in the fourth invention, the second member is configured to cover at least a part of the substrate placement stage exposed to the processing gas supplied into the process chamber.
As the sixth invention, in the substrate processing apparatus described in the fourth invention or the fifth invention, the substrate processing apparatus further includes a third member configured to support at least a periphery of a lower surface of the first member and having lower thermal deformation than the first member.
As the seventh invention, in the substrate processing apparatus described in the fourth invention or the fifth invention, the substrate processing apparatus further includes a third member supporting at least a periphery of a lower surface of the first member and having a lower thermal conductivity than the first member.
The eighth invention relates to a method of manufacturing a substrate placement stage, the method including: inserting a heating element into a ceramic material; immersing the ceramics material into which the heating element is inserted in molten aluminum; and impregnating the ceramics material immersed in the molten aluminum by pressurizing the molten aluminum.
The ninth invention relates to a method of manufacturing a semiconductor device using a substrate processing apparatus including: a process chamber configured to process a substrate; a gas supply unit configured to supply a processing gas into the process chamber; a gas exhaust unit configured to exhaust the processing gas from an inside of the process chamber; and a substrate placement stage installed in the inside of the process chamber including: a heating element; a first member surrounding the heating element; and a second member covering a surface of the first member, wherein the first member is made of a first material containing ceramics and aluminum, and the second member is made of a second material containing ceramics and aluminum, a content of the ceramics in the second material being lower than that of the first material, the method including: loading the substrate into the process chamber and placing the substrate on the substrate placement stage; heating the substrate using the heating element; supplying the processing gas into the process chamber using the gas supply unit; exhausting the processing gas from the process chamber using the gas exhaust unit; and unloading the substrate from the inside of the process chamber.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-117723 | May 2011 | JP | national |
| 2012-107668 | May 2012 | JP | national |
