TWI640053B - Substrate support table and manufacturing method thereof - Google Patents

Abstract

A substrate support table includes an electrostatic chuck, a heater, and a base. An electrostatic chuck is mounted above the heater, and the heater is fixed to the upper surface of the base. Wherein the base includes a cooling liquid circulation pipe; the heater includes a heating element for generating heat, and further includes an upper insulating material layer above the heating element and a lower insulating material layer below the heating element, the lower insulation The bottom surface of the material layer is fixed to the upper surface of the base, wherein the thickness of the lower insulating material layer is greater than 1 mm, and the lower insulating material layer includes at least one metal layer to separate the lower insulating material layer into a plurality of insulating material sub-layers.

Description

Substrate support table and manufacturing method thereof

The invention relates to the technical field of semiconductor manufacturing, and in particular to a substrate support table used in a reaction chamber of a plasma processor.

Plasma processors are widely used in the semiconductor industry for high-precision processing of substrates to be processed, such as plasma etching and chemical vapor deposition (CVD). The plasma processor includes a reaction chamber, and a substrate support table at the bottom of the reaction chamber is used to place and fix the substrate. In addition to fixing the substrate, the support table needs to control the temperature of the substrate, so it needs to be able to take away the heat generated in the plasma processing. At the same time, the support table is also connected to an RF power supply, which adjusts the processing effect on the substrate by adjusting the output power of the RF power supply . Therefore, the substrate support table is a core and multifunctional device in a plasma processor, which has a significant impact on the processing effect of the substrate.

With the development of the semiconductor industry, more and more plasma processing processes have been developed. Each process requires different optimal temperature parameters. Often, multiple processes in a single substrate need to be processed continuously in the same reaction chamber. In the process steps, the corresponding optimal temperature needs to be quickly switched. In order to achieve the requirement of rapid temperature change, the existing mechanism is designed in the structure of the substrate support table as shown in FIG. 1, including a base 10 ′, and a cooling liquid pipe 11 ′ for cooling liquid circulation is opened in the base 10 ′ to take away Heat, the base includes a heater. The heater is composed of two layers of insulating materials 23 ', 21' and a heating element such as a resistance wire 29 'located between the layers of insulating materials. The upper surface of the insulating material layer on the heater is made of silicone The layer 32 'is fixed in combination with the electrostatic chuck 30' above. The base is generally made of metal, such as aluminum alloy, and is electrically connected to at least one radio frequency power source. The insulating material layers 21 ', 23' generally, AlN, Y ₂ O ₃ and the like made of a ceramic material such as AL ₂ O _3. During the temperature switching process, if the temperature needs to be lowered, the heating power output is turned off. The coolant in the coolant pipe below takes the heat away. The heater receives electric power to generate a lot of heat during the heating process. The coolant also needs to be circulated to take away. Upper heater and heat generated by plasma and RF power during processing. Therefore, a large amount of heat generated by the heater during the heating process is directly taken away by the base 10 'below, and does not reach the substrate on the electrostatic chuck 30' upward. In order to reduce this heat loss and speed up the heating process, it is necessary to have a lower thermal conductivity between the heating element 29 'and the lower cooling liquid pipe 11'. For example, the base 10 'uses a metal material with a lower thermal conductivity, titanium ( (About 20 W / mk) or make the insulating material layer 21 'under the heating element 29' thicker.

However, these two solutions have problems: the titanium material is too expensive, and its price exceeds 4 times that of the aluminum alloy material (thermal conductivity coefficient 170W / mk); when the thickness of the insulating material layer 21 'increases to more than 1mm, due to the aluminum alloy and the insulation below The thermal expansion coefficient of the material layer has a large difference, and the insulating material layer 21 'will quickly break and fail during frequent temperature changes. Therefore, in the prior art, the thickness of the insulating material layer 21 'is generally between 0.5 and 1 mm. Such a small thickness also results in difficulty in controlling the unevenness of the thickness of the insulating material layer over the entire plane, because the insulating material layer is usually sprayed. The surface roughness is very large, and tolerances formed by common processes will cause uneven thickness of the insulating material layer. For a 0.5mm thick material layer, when the thickness difference of the insulating material in different parts reaches 25um, the thickness difference between different regions can reach 5%, and the temperature of the substrate above the substrate support table will be affected accordingly and very It is difficult to obtain a uniform temperature distribution. Therefore, the industry needs a new method or device to solve the problem on the substrate support table, which can quickly change the temperature of the substrate, and also needs to make the temperature of the substrate more uniform.

The problem to be solved by the present invention is to provide a substrate support table including: an electrostatic chuck, a heater, and a base. The electrostatic chuck is installed above the heater, and the heater is fixed to the upper surface of the base; wherein the base includes a cooling liquid. A circulation pipe; the heater includes a heating element for generating heat, and further includes an upper insulating material layer above the heating element and a lower insulating material layer below the heating element, and a bottom surface of the lower insulating material layer is fixed to the base The upper surface, wherein the thickness of the lower insulating material layer is greater than 1 mm, and the lower insulating material layer includes at least one metal layer to separate the lower insulating material layer into a plurality of insulating material sub-layers. The thickness of a plurality of insulating material sub-layers is less than 1 mm to prevent the insulating material layer from cracking during temperature changes. The thickness of the insulating material sub-layers is preferably less than 0.5 mm and greater than 0.2 mm.

Among them, the metal layer of the present invention is best selected in a grid shape, and the base is made of aluminum alloy.

Preferably, the lower insulating material layer may include two metal layers to separate the lower insulating material layer into first, second, and third insulating material sub-layers.

In the present invention, the insulating material layer is made of a ceramic material or an organic material, the ceramic material includes one of alumina, aluminum nitride, and yttrium oxide, and the organic material is selected from one of PEEK, Vespel, and Kapton.

The electrostatic chuck of the substrate supporting table of the present invention is connected to the upper insulating material layer on the top of the heater through a layer of silicon rubber.

The invention also provides a method for manufacturing a heater for a substrate supporting table, comprising the steps of: A. forming an insulating material layer having a thickness of less than about 1 mm on a base material; B. forming a grid-like metal layer on the insulating material layer; C. Repeat the above steps A to B to form a lower insulating material layer, which includes alternating insulating material layers and metal layers, wherein the top layer is an insulating material layer; D. On top A heating element is formed on the insulating material layer of the layer; E. An upper insulating material layer is formed on the heating element.

10, 10’‧‧‧ base

11‧‧‧Coolant circulation pipe

11’‧‧‧Coolant pipe

22, 24‧‧‧ metal layer

21, 21 ’, 23, 23’, 25, 27‧‧‧ insulating material layers

29, 29’‧‧‧ heating element

30, 30’‧‧‧ electrostatic chuck

32, 32’‧‧‧ Silicone layer

FIG. 1 is a schematic diagram of a prior art substrate support table; FIG. 2 is a schematic diagram of a substrate support table of the present invention.

As shown in FIG. 2, a schematic diagram of a substrate support table according to the present invention is shown. The basic structure of the present invention is similar to that of the prior art shown in FIG. 1, and includes an electrostatic chuck 30, a silicone layer 32, a heating element 29 and The main difference between the pedestal 10 is that the substrate support table of the present invention includes multiple layers of insulating material layers 21, 23, 25, and 27. Two insulating metal layers 22 and 24 are embedded between the insulating material layers and the upper layer Heating element 29. The materials used for the metal layers 22 and 24 are similar to the lower base 10 and have good ductility, and the overall thickness is very low (less than 0.1 mm), and the coverage area is also small, so the thermal conductivity in the up-down direction is not increased. The thickness of the insulating material layers 21 to 27 can be selected as 0.5-1 mm or less as in the prior art, but the present invention can prevent these insulating material layers from being arranged by setting the metal grid layers 22 and 24 between different insulating material layers. Rupture during temperature changes. In the prior art, if the thickness of the entire insulating material layer 21 exceeds 1 mm, the relative displacement between the thickness of the entire insulating material layer 21 and the aluminum alloy base 10 causes the material layer 21 to break. Each layer of the insulating material layer in the present invention The thickness is less than 1mm. These thin insulating material layers 21, 23, 25, and 27 are only relatively displaced by the base 10 and the grid-like metal layers 22 and 24 which are directly combined with each other, so each insulating material layer is not easy to crack. However, the overall thickness of the overall insulating material layer is far greater than the thickness of 1mm, which can reach a maximum of about 3mm. This thickness is sufficient to prevent a large amount of heat from being transmitted downward during the heating process. To prevent cracking, each layer of insulating material 21, 23, The thickness values of 25 and 27 can be lower, for example, 0.5mm smaller than 0.2mm. By setting more layers of metal-insulating material layer units to overlap, the thickness of the overall insulating material layer below the heating element 29 is greater than 1mm. Effective thermal insulation while avoiding cracks in the insulating material layer.

After the total thickness of the insulating material layer is increased, the uniformity of the thickness of the overall material layer is easier to control. The same processing process brings a tolerance of 25um. Compared with the larger thickness after the solution of the present invention, the thickness of The total error can be controlled below 2%, which brings additional benefits to the uniformity of the temperature of the upper substrate. The arrangement of the grid-like metal layer in the present invention can prevent the insulation material layer from cracking. Even if a slight crack occurs in a local area, since the insulation material is combined with the grid-like metal, these cracked portions will still be pulled by the metal material. Live without falling off. Therefore, using the substrate supporting table of the heater structure of the present invention can obtain a thicker insulating material layer while preventing the heater from cracking.

The substrate support table of the structure of the present invention is particularly effective for processes that require high-temperature processing of the substrate. During the high-temperature processing process, the difference between the temperature of the substrate and the temperature of the underlying pedestal may be greater than 50 degrees or even 100 degrees. Because the heater with better thermal insulation effect provided by the present invention can make the heat generated in the heating element 29 mainly heat the electrostatic chuck 30 and the substrate above the electrostatic chuck 30, not only the temperature rising speed is fast, but the process switching time can be reduced. It also saves energy.

In the present invention, the grid-like metal layers 22 and 24 may also be metal discs, which can also achieve the purpose of the present invention and avoid cracking of the insulating material layer. In the present invention, the insulating material layer may be ceramic materials such as alumina, aluminum nitride and the like, as well as insulating materials made of organic polymers. These organic insulating materials may be PEEK (polyetherether) available on the market. Ketone), Vespel (fully aromatic polyimide resin), Kapton (polyimide film), etc., can be applied to the present invention as long as it is an insulating and low thermal conductivity material.

The present invention also provides a manufacturing process of a substrate supporting table. The manufacturing process of the substrate supporting table includes: A. manufacturing the aluminum alloy base 10 with the cooling liquid circulation pipe 11 by a traditional machining process; B. spraying the insulating material particles to An insulating material layer 21 with a thickness of about 0.5 mm is formed on the base material, and the formation of the insulating material layer 21 is completed after curing. The spraying process can be arc spraying, plasma spraying, or in addition to the spraying process, chemical vapor deposition can also be used to form the insulating material layer. The insulating material layer formed in this way is more dense and uniform; C. The grid-like metal layer 22 is formed, and the forming process can be spray coating or direct metal foil laying; D. Repeat the above steps B to C to form the insulating material layers 23, Metal layer 24, insulating material layer 25; E, forming a heating element 29 on the insulating material layer 25; F, performing step B again to form an insulating material layer 27.

After the manufacture of the heater and the base 10 is completed, an adhesive material layer such as silicon rubber may be further coated on the upper surface of the insulating material layer, and an electrostatic chuck is placed on the adhesive material layer to complete the manufacture of the entire substrate support table. The number of repeated executions of steps B to C in the above step D can be optimally set as required. The more the number of repeated executions, the more the number of overlapping layers of the insulating material layer and the grid-like metal layer, until the insulation effect required by the process is achieved. The manufacturing process of the present invention may also be to first manufacture and manufacture the special heater of the present invention, and then glue the heater to the upper surface of the lower base 10 through an adhesive layer. The manufacturing process of the heater is similar to the aforementioned A to F, but The lower insulating material layer is manufactured directly on the base material. Various insulating material layers and metal layers are sequentially grown on the bottom, and then a heating element 29 and an upper insulating material layer are formed. Finally, the heater is detached from the base material and fixed to the aluminum base 10 prepared in advance.

Although the present invention is disclosed as above, the present invention is not limited thereto. Any person with ordinary knowledge in the technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the scope of patent application for invention.

Claims (8)

A substrate support table includes: an electrostatic chuck, a heater, and a base, the electrostatic chuck is mounted above the heater, the heater is fixed to the upper surface of the base, and the base includes a A cooling fluid circulation pipe; the heater includes a heating element for generating heat, and further includes an upper insulating material layer above the heating element and a lower insulating material layer below the heating element, and the bottom surface of the lower insulating material layer is fixed to The upper surface of the base, wherein the thickness of the lower insulating material layer is greater than 1 mm, and the lower insulating material layer includes at least one metal layer to separate the lower insulating material layer into a plurality of insulating material sub-layers, and the metal layer is in a grid shape. Where the lower insulating material layer includes two metal layers, and the lower insulating material layer is separated into a first insulating material sublayer, a second insulating material sublayer, and a third insulating material sublayer. The substrate supporting table according to item 1 of the scope of patent application, wherein the plurality of insulating material sub-layers have a thickness of less than 1 mm. The substrate supporting table according to item 2 of the scope of patent application, wherein the plurality of insulating material sublayers have a thickness of less than 0.5 mm and greater than 0.2 mm. The substrate supporting table according to item 1 of the patent application scope, wherein the base is made of aluminum alloy. The substrate supporting table according to item 1 of the scope of patent application, wherein the upper insulating material layer and the lower insulating material layer are made of ceramic material, and the ceramic material includes one of aluminum oxide, aluminum nitride, and yttrium oxide. The substrate supporting table according to item 1 of the scope of patent application, wherein the upper insulating material layer and the lower insulating material layer are made of an organic material, and the organic material is selected from one of PEEK, Vespel, and Kapton. The substrate supporting table according to item 1 of the scope of the patent application, wherein the electrostatic chuck is connected to the upper insulating material layer on the top of the heater through a layer of silicone. A method for manufacturing a heater in a substrate supporting table according to item 1 of the scope of patent application, comprising the following steps: A. forming an insulating material layer having a thickness of less than 1 mm on a base material; B. forming an insulating material layer on the substrate material; A grid-like metal layer is formed thereon; C. An insulating material layer of less than 1 mm is formed on the grid-like metal layer; steps B to C described above are repeatedly performed to form a lower insulating material layer, and the lower insulating material layer includes alternating layers. An insulating material layer and a metal layer; D. forming a heating element on the top insulating material layer; E. forming an upper insulating material layer on the heating element.