The present invention relates to a crucible for accommodating and heating a material to be vaporized or sublimed, and in particular, to a crucible applicable to accommodating and heating a reactive material, and a system for vaporizing or subliming a material. The system includes the crucible and a heater arrangement for heating the crucible. The crucible and the system are especially applicable to solar cell manufacturing, and a sulphureous or selenium-contained material thereof is vaporized or sublimed.
A technology used for depositing a material on a substrate is chemical vapor deposition. Steam of the to-be-deposited material is generated from the material source when the material is vaporized or sublimed due to a high temperature (a temperature higher than a temperature making the material boiling or sublimed). Vaporized material granules move toward the substrate and finally deposit on a surface of the substrate. Usually, a crucible for accommodating the to-be-deposited material (that is, the material source) is heated by using a heating lamp, an RF coil, or a resistive heater that is placed on the outside of the crucible or placed at a distance from the crucible. A heater or a heating element is usually thermally separated from the crucible, and heat energy is transferred by radiation or air convection at a large distance. For example, U.S. Pat. No. 6,444,043B1 describes a crucible or a container. The crucible or the container is made of one piece of graphite and has a recess or an opening for maintaining the material to be vaporized or sublimed. The crucible is heated by using a heating lamp placed on a sealed side periphery of the crucible and at a distance from the crucible. In US2014/0109829A1, a vaporizing unit includes a crucible and a heater frame which is isolated from the crucible and is set surrounding a lateral surface and a bottom surface of the crucible. A heater for heating the crucible is provided on an inner surface of the heater frame that faces the crucible.
If a space in which the heater is arranged is not sealed, so as to prevent the space from being affected by a space in which vaporized material is scattered, the to-be-deposited material will reach the heater. Consequently, a material with a low heating efficiency may deposit on the surface of the heater, and a material of the heater may be corroded by the to-be-deposited material or a constituent of the to-be-deposited material. For example, the heater may be corroded in a sulphureous atmosphere.
In addition, because the heater is placed at a distance from the crucible, heat transfer is limited by a space and a material in the space between the heater and the crucible.
Therefore, an objective of the present invention is to provide a crucible and a system that comprises the crucible and a heater arrangement. The heater arrangement provides good protection for a heater, to prevent the heater from being affected by surrounding processing atmosphere or possible corrosive processing atmosphere, and provides an improved manner of transferring heat from the heater to the crucible and a simple manner for joining and separating system components.
In order to accomplish the above object, the present invention provides the crucible as in claim 1 and the system, as in claim 6, for vaporizing or subliming a material. Embodiments are comprised in the dependent claims.
The crucible for heating a material to be vaporized or sublimed according to the present invention comprises at least one concave recess, and a bottom recess and/or a side recess. The concave recess is applicable to accommodating the material to be vaporized or sublimed and is formed on a first surface (also referred to as a top surface) of the crucible. Therefore, the concave recess forms an opening of the crucible on the top surface. The bottom recess is formed on a second surface of the crucible. The second surface is opposite to the first surface and is alternatively referred to as a bottom surface. The bottom recess forms an opening on the bottom surface of the crucible and is applicable to accommodating a bottom heater for heating the bottom surface of the crucible. The side recess is formed in a side wall of the crucible. The side wall extends from the first surface to the second surface and connects the top surface to the bottom surface. The side recess forms a hollow space in the side wall of the crucible and has an opening near the second surface of the crucible. That is, the side recess does not form an opening on a side surface of the crucible, or in other words, the side wall is not open toward a side portion. The side surface is a surface that is of the side wall and that is opposite to a surface of the side wall that is near the concave recess and the bottom recess. In addition, the side surface is one of external surfaces of a body of the crucible. The side recess is applicable to accommodating a side heater that is used for heating the side surface of the crucible.
An external form of the crucible is not limited in any situation, provided that the crucible has a top surface, a bottom surface, and at least one side wall. That is, the crucible may be, for example, a right cylinder or an oblique cylinder that has a circular or oval top surface and/or bottom surface, or a right prism or an oblique prism (for example, a cuboid) of any type, or a form of any type. All recesses are able to extend, to maintain at least a minimum thickness of the material of the crucible at all points, wherein the minimum thickness of the material of the crucible is applicable to ensuring physical stability of the body of the crucible. For example, the minimum thickness of the material of the crucible of a wall that separates the concave recess from the bottom recess or that separates the concave recess from the side recess is in a range from 10 mm to 15 mm relative to graphite used as the material of the crucible and relative to an external size of the body of the crucible that reaches 1.5 m. However, different recesses may have different lengths and/or widths. For example, the concave recess may be smaller than the bottom recess in a lateral size. A size of the concave recess depends on a volume of the material to be vaporized or sublimed and required to be accommodated in the concave recess. A size of the bottom recess and a size of the side recess are selected according to a size of a corresponding heater, and make the corresponding heater completely accommodated (where a connection for providing energy to the heater, if applicable, is excluded) in the corresponding recess. Because the heater (the side heater in particular) is completely accommodated in the corresponding recess of the crucible, the heater is almost completely isolated from a processing atmosphere existing when the material accommodated in the concave recess is vaporized or sublimed. Therefore, the crucible according to the present invention is provided for the heater for excellent protection, to prevent the heater from being affected by a corrosive or reactive constituent of the processing atmosphere. In addition, because the heater may be arranged to be extremely close to the crucible, that is, “in” the body of the crucible, for example, in the side wall of the crucible, therefore, heat transfer from the heater to the material that is to be vaporized or sublimed and accommodated in the concave recess is improved, resulting in a higher achievable temperature or potentially reduced energy required to achieve a specific temperature.
In addition, more than one side recess (for example, two or three or more side recesses) may be formed in a particular side wall, wherein all side recesses have an opening near the second surface of the crucible. Different side recesses in a particular side wall are separated from each other by a material strip formed by the material of the side wall, wherein the material strip forms a middle wall between corresponding side recesses and can extend from the first surface to the second surface of the crucible and through the entire thickness of the side wall. More than one bottom recess may also be formed on the second surface of the crucible, wherein different bottom recesses are separated from each other by a material strip formed by the material of the crucible.
Based on the external form of the crucible, the crucible may have a plurality of side walls. For example, if the crucible is a cuboid, then the crucible has four side walls. In this case, one side recess may be formed in one of the side walls, or more than one side recess may be formed in more than one of the side walls. In other words, each side recess is formed in a particular side wall of the side walls of the crucible. Further, more than one side recess may be formed in a particular side wall, or more than one side wall or even all side walls, as described above. The number of side recesses in a particular side wall may vary as the side wall varies. In an embodiment, a different side recess of the side recesses is formed in all the side walls of the crucible. That is, the number of the side recesses is equal to the number of the side walls of the crucible. Different side recesses may have different sizes in any situation.
In a particular embodiment, the crucible comprises the side recess, and further comprises a heat insulation recess, the heat insulation recess is near the side recess and formed on a side wall the same as that of the side recess of the crucible. The heat insulation recess is formed on a side of the side recess that is not near the concave recess of the crucible. The side recess is separated from the heat insulation recess by the material of the crucible. The heat insulation recess is formed with a similar size as that of the side recess, extends from the second surface of the crucible, and has an opening near the second surface of the crucible. The heat insulation recess may be filled with air or any other solid, liquid or gaseous material, if the opening of the heat insulation recess is covered by a cover or any other suitable apparatus, then the heat insulation recess may be evacuated. The heat insulation recess serves as a heat insulation layer or a heat shield that reduces heat transfer to the side surface of the side wall. Therefore, the heat insulation recess further improves heat transfer from the side heater to the material that is to be vaporized or sublimed and accommodated in the concave recess.
Preferably, the crucible is made of a material that has a high heat conductivity and that is noble and non-diffused relative to the material to be vaporized or sublimed or relative to a constituent of an environmental atmosphere (for example, a processing atmosphere existing when the material accommodated in the concave recess is vaporized or sublimed). Therefore, the crucible itself does not react with the material to be vaporized or sublimed or the constituent of the environmental atmosphere. In addition, the crucible reduces or prevents the reactive constituent from passing through a wall of the crucible and being diffused to the heater, so that even if the heater is made of a material that is non-noble relative to the material accommodated in the concave recess or relative to the constituent of the environmental atmosphere, the heater is also prevented from deteriorating or being damaged. Therefore, a material with a low price (for example, stainless steel used for a resistive heater) may be used for the heater. The material of the crucible (for example) is selected from a material group comprising graphite, silicon carbide, and an oxide ceramic material (for example, aluminum oxide).
As described above, the crucible according to the present invention may be applied to a system for vaporizing or subliming a material. The system further comprises a heater arrangement for heating the crucible. The heater arrangement comprises at least one heater arranged in the bottom recess or the side recess of the crucible. The at least one heater may be a heater of any type, wherein an induction heater or a resistive heater is preferred. If more than one heater (for example, a bottom heater arranged in the bottom recess and a side heater arranged in the side recess) is used, then different heaters may be heaters of different types and sizes. If all heaters are heaters of a same type, then these heaters may be connected to each other or completely separated, so that heat energy provided by a particular heater may be controlled independent of heat energy provided by another particular heater.
If the crucible comprises a plurality of side recesses, then the heater arrangement comprises a plurality of heaters, wherein a particular heater of the heaters is arranged in each of the side recesses. Therefore, heat transfer to the crucible may be well controlled from all sides of the concave recess (except the top surface serving as a vaporization opening). In addition, the temperature of the material accommodated in the concave recess may be highly even.
Because the heater is arranged in the recess of the crucible, the heater (the side heater in particular) is protected by the crucible from being damaged by the reactive constituent of the environmental atmosphere. Therefore, the heater may be made of the material that is non-noble relative to the material to be vaporized or sublimed or relative to the constituent of the environmental atmosphere. In this way, the heater may be used for a relatively long time, and there does not exist deterioration of heat generation or heat transfer caused by damaged heater. In addition, extra gases may be applied to a vaporizing or subliming process without chemically corroding the heater. Therefore, the system of the present invention has the following advantages: a reduced machine downtime caused by necessary replacement of the heater (where this is true even a reactive or corrosive constituent is used during processing); highly efficient heat transfer and economical energy use; and simple and compact setting of the system.
To further protect the heater, the heater may be coated with a material that has a high heat conductivity and that is noble and non-diffused relative to the material to be vaporized or sublimed or relative to a constituent of an environmental atmosphere.
When the system is mounted or arranged in a processing chamber to make the crucible arranged on a mounting panel in the chamber or on a chamber wall of the processing chamber, the opening of the bottom recess and/or the opening of the side recess are covered and sealed respectively, to prevent them from being affected by an atmosphere (for example, the processing atmosphere) that is outside of the recess. Certainly, providing energy to the heater arranged in the corresponding recess should be ensured by using, for example, an opening that is in the mounting panel or chamber wall and through which a connection line of the heater may pass, or by using an interface that provides connection between the heater in the recess and the outside world and that is arranged in the mounting panel or chamber wall. The term “seal” does not necessarily mean “airtight”, but mean that a corrosive constituent is apparently less diffused to the recess. With reference to the crucible and the structure described above of the system that comprises the crucible and the at least one heater, degrading of the heater caused by the corrosive environmental atmosphere can be significantly reduced, while providing a simple structural setting and assembling for the system.
However, one or more or all of the bottom recess and/or the side recess of the crucible may be covered or sealed by using one or more shield covers or covers. That is, the bottom recess and all side recesses may be sealed by a particular shield cover, thereby being protected from the impact of the environmental atmosphere. Alternatively, only the bottom recess is sealed. Alternatively, only one side recess or more recesses selected from the bottom recess and the side recess are sealed, instead of sealing all recesses. The shield cover or cover may be mounted on the crucible or the system or other components of the processing chamber, and may be made of any suitable material (for example, the material of the crucible). As described above with respect to the mounting panel or the chamber wall, providing energy to the heater arranged in the corresponding recess should be ensured by using, for example, an opening that is in the corresponding shield cover and through which a connection line of the heater may pass, or by using an interface that provides connection between the heater in the recess and the outside world and that is arranged in the corresponding shield cover. Such a shield cover may be particularly applicable to the following situation: The mounting panel or any other mounting system has an opening, so that the bottom recess and/or the side recess is not sealed by the mounting panel or the mounting system.
The accompanying drawings are comprised in the specification, to provide further understanding of embodiments of the present invention, and are integrated into the specification of the present invention and form a part of the specification of the present invention. The accompanying drawings describe the embodiments of the present invention and are used for explaining the principle together with the specification of the present invention. Other embodiments and many expected merits of the present invention can be easily learned, for the embodiments and expected merits can be better understood with reference to the following detailed descriptions. Elements in the accompanying drawings are not necessarily scaled by proportion relative to each other. Similar reference signs represent similar parts.
Table 1 shows exemplary sizes of the crucible 10 and different elements of the crucible 10. As is clearly understood, the crucible 10′ may have a similar size, and the side recesses 13aa to 13ac and the side recesses 13ca to 13cc are relatively small in the y direction.
As is clearly known by those skilled in the art, the heater of the heater arrangement is fixed relative to the crucible 10 and the processing chamber 200 anyhow. This case is also suitable for the crucible 10 itself. That is, the heater of the heater arrangement may be fixed in a corresponding recess (the bottom recess and/or the side recess), or may be fixed on the mounting panel 220 or the chamber wall 230 or one or more shield covers. The one or more shield covers are mounted to the bottom surface of the crucible 10 and seal a corresponding recess. Therefore, even if the recess is not sealed by any component of the system, the heater may not drop out of the recess of the crucible. In order to arrange the heater of the heater arrangement in the corresponding recess of the crucible 10, the heater may be inserted into a recess for fixing the crucible, or the crucible 10 may slide from the top of a fixed heater. However, the two components (the crucible and the heater) are movable, so that the heater is inserted into the corresponding recess of the crucible.
Because the heater of the heater arrangement is arranged in the crucible 10, heat transfer from the heater to the material 30 is optimized. In addition, the recess of the crucible 10 where the heater is arranged is sealed by the mounting panel 220, so that the heater is effectively prevented from being affected by an environmental atmosphere in the chamber 200. The environmental atmosphere may comprise a constituent that is corrosive relative to a material of the heater. In addition, the crucible 10 may be separated from the heater by simply lifting the crucible 10 to make the crucible 10 away from the mounting panel 220. Therefore, if a first crucible 10 must be cleaned or another material 30 must be vaporized or sublimed, then the first crucible 10 may be replaced with a second crucible 10 without detaching the heater arrangement.
The embodiments of the present invention described above are examples shown through description, and the present invention is not limited to this. All modifications, variations, equivalent arrangement, and combinations of the embodiments shall fall within the scope of the present invention.
Number | Date | Country | Kind |
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201511026677.3 | Dec 2015 | CN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CN2016/112150 | 12/26/2016 | WO | 00 |