TWI837758B - Base support structure and epitaxial growth device - Google Patents

Abstract

The present invention relates to a base support structure for supporting a base in an epitaxial growth device. The base support structure includes a main support shaft and a plurality of support arms extending outward from the main support shaft. The main support shaft includes a first part and a second part along its extension direction. A plurality of support arms are arranged on the first part, and the weight of the first part is less than the weight of the second part. The present invention also relates to an epitaxial growth device. The main support shaft is divided into a first part and a second part along its extension direction. A plurality of support arms are arranged on the first part. When supporting the base, the first part is arranged close to the base. In an embodiment of the present invention, the weight of the first part is less than the weight of the second part, thereby moving the center of the main support shaft downward, thereby improving the problem of easy deviation during rotation.

Description

Base support structure and epitaxial growth device

The present invention belongs to the field of silicon wafer epitaxial growth technology, and in particular to a base support structure and an epitaxial growth device.

Epitaxial growth technology of silicon wafers is an important technology for semiconductor chip manufacturing. It is a method of growing a silicon single crystal layer with high resistivity, controllable thickness, no crystal native pits (COP) and oxygen-free deposition on a polished wafer as a substrate under certain conditions. It mainly includes vacuum epitaxial deposition, vapor phase epitaxial deposition and liquid phase epitaxial deposition. Among them, vapor phase epitaxial deposition is the most widely used. In a high temperature environment, the epitaxial layer is obtained by reacting silicon source gas with hydrogen to generate single crystal silicon and deposit it on the surface of the silicon wafer. At the same time, a _doping agent ( _B2H6 or _PH3 ) is introduced to dope the epitaxial layer to obtain the required resistivity.

Generally, the epitaxial growth device includes a reaction chamber formed by an upper quartz bell and a lower quartz bell. A base for carrying a silicon wafer and a base support rod for supporting the base are arranged in the reaction chamber. The base support rod plays the role of fixing the base and driving the base to rotate so that the epitaxial growth can be carried out uniformly on the substrate. A heating bulb responsible for providing reaction energy is arranged outside the quartz bell, providing heat for the reaction by thermal radiation.

Since the gas enters the chamber in a single direction during the epitaxial growth process, the silicon wafer needs to be rotated during the growth process to ensure uniform growth. The silicon wafer is placed on top of the base, which is supported and rotated by the base support rods. During the epitaxial growth process, the center of gravity of the base support rods and the base as a whole is very high, so there is a high possibility of offset during the rotation process. During the epitaxial growth process, the offset of the base support rods will cause the base and the silicon wafer it supports to shift synchronously, which will cause uneven thickness of the epitaxial layer.

In order to solve the above technical problems, the present invention provides a base support structure and an epitaxial growth device to solve the problem of uneven thickness of the epitaxial layer caused by base offset.

In order to achieve the above-mentioned purpose, the technical solution adopted in the embodiment of the present invention is: a base support structure, used to support the base in the epitaxial growth device, the base support structure includes a main support shaft, and a plurality of support arms extending outward from the main support shaft, the main support shaft includes a first part and a second part along its extension direction, and a plurality of the support arms are arranged on the first part, and the weight of the first part is less than the weight of the second part.

Optionally, the first part is a hollow structure and the second part is a solid structure.

Optionally, in the extension direction of the main supporting axis, the lengths of the first portion and the second portion are the same.

Optionally, a plurality of the support arms extend radially outward from the main support axis and are arranged to extend away from the second portion, and an angle between each of the support arms and the radial direction of the main support axis is within a first threshold range.

Optionally, the first threshold range is 0-30 degrees.

Optionally, a plurality of the support arms extend radially outward from the main support axis and are arranged in a direction close to the second portion, and an angle between each of the support arms and the radial direction of the main support axis is within a second threshold range.

Optionally, the second threshold range is 0-60 degrees.

Optionally, a plurality of the support arms are evenly arranged on the outer circumferential surface of the main support shaft.

Optionally, three supporting arms are included, and the angle between two adjacent supporting arms is 120 degrees.

The embodiment of the present invention also provides an epitaxial growth device, comprising: A reaction chamber formed by two quartz bell jars arranged opposite to each other; A base located in the reaction chamber and used to support a silicon wafer; A heating structure used to provide heat to the reaction chamber; And the above-mentioned base support structure.

The beneficial effect of the present invention is that the main support shaft is divided into a first part and a second part along its extension direction, a plurality of support arms are arranged on the first part, and when supporting the base, the first part is arranged close to the base. In the embodiment of the present invention, the weight of the first part is less than the weight of the second part, thereby moving the center of the main support shaft downward, thereby improving the problem of easy deviation during rotation.

In order to help you understand the technical features, contents and advantages of the present invention and the effects it can achieve, the present invention is described in detail as follows with the accompanying drawings and appendices in the form of embodiments. The drawings used therein are only for illustration and auxiliary description, and may not be the true proportions and precise configurations after the implementation of the present invention. Therefore, the proportions and configurations of the attached drawings should not be interpreted to limit the scope of application of the present invention in actual implementation.

In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be a connection between two components or an interaction relationship between two components. For those with ordinary knowledge in the field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

Referring to FIG. 1 , the epitaxial growth device includes a reaction chamber 10 formed by an upper quartz bell jar and a lower quartz bell jar. A susceptor 3 for supporting a silicon wafer and a preheating ring 4 arranged around the periphery of the susceptor 3 are arranged in the reaction chamber 10. The preheating ring 4 is spaced apart from the susceptor 3 and is used to support a susceptor 3 supporting rod. The susceptor 3 supporting rod plays the role of fixing the susceptor 3 and driving the susceptor 3 to rotate so that the epitaxial growth can be carried out evenly on the substrate.

Since the gas enters the chamber in a single direction during the epitaxial growth process, the silicon wafer needs to be rotated during the growth process to ensure uniform growth. The silicon wafer is placed on the base 3, and the base 3 is supported and driven to rotate by the base 3 support rods. During the epitaxial growth process, the center of gravity of the base 3 support rods and the base 3 as a whole is very high, so there is a high possibility of offset during the rotation process. During the epitaxial growth process, the offset of the base 3 support rods will cause the base 3 and the silicon wafer it carries to shift synchronously, which will cause uneven thickness of the epitaxial layer. In particular, the edge of the susceptor 3 has a first position and a second position relative to each other, and a line connecting the first position and the second position passes through the center of the susceptor 3 and extends along the radial direction of the susceptor 3. At the first position, the distance between the susceptor 3 and the preheating ring 4 is a, and at the second position, the distance between the susceptor 3 and the preheating ring 4 is b. Due to the displacement of the susceptor 3, when a>b, the thickness of the epitaxial layer near the first position will decrease, and the epitaxial layer near the second position will decrease. When a＜b, the thickness of the epitaxial layer near the first position will increase, and the thickness of the epitaxial layer near the second position will decrease, that is, the offset of the base 3 will cause the overall thickness of the epitaxial layer to deviate from the normal value, and ultimately lead to the deterioration of the flatness of the epitaxial layer shown in FIG4 (FIG. 4 is the local flatness of the silicon wafer when measured by the silicon wafer flatness (SFQR) in the silicon wafer flatness index, the lower the value, the better the flatness of the silicon wafer).

2 and 3 , in view of the above problems, the present embodiment provides a base 3 supporting structure for supporting the base 3 in an epitaxial growth device, wherein the base 3 supporting structure includes a main supporting axis 1 and a plurality of supporting arms 2 extending outward from the main supporting axis 1, wherein the main supporting axis 1 includes a first portion 101 and a second portion 102 along its extending direction, wherein the plurality of supporting arms 2 are disposed on the first portion 101, and the weight of the first portion 101 is less than the weight of the second portion 102.

When used to support the base 3, the first part 101 is arranged close to the base 3, and the second part 102 is arranged far away from the base 3. In this embodiment, the main supporting axis 1 is arranged so that the weight of the first part 101 is less than the weight of the second part 102, and the center of gravity of the main supporting axis 1 is moved downward, thereby improving the offset caused by the high center of gravity, thereby improving the uniformity of the epitaxial layer.

In order to move the center of gravity away from the first part 101, that is, to move the center of gravity of the main supporting axis 1 away from the base 3, in the extension direction of the main supporting axis 1, the length of the first part 101 is greater than one-third of the main supporting axis 1. In some embodiments of this embodiment, in the extension direction of the main supporting axis 1, the length of the first part 101 and the second part 102 are the same, that is, in the extension direction of the main supporting axis 1, the length of the first part 101 is half of the main supporting axis 1, but it is not limited to this.

In order to make the weight of the first part 101 less than the weight of the second part 102, the specific structural settings of the main supporting shaft 1 can be various. For example, a plurality of through holes or grooves are set on the outer peripheral surface of the first part 101, and the second part 102 is a solid structure, or the first part 101 is a hollow structure, and a plurality of through holes or grooves are set on the outer peripheral surface of the second part 102. In some embodiments of the present embodiment, the first part 101 is a hollow structure and the second part 102 is a solid structure, thereby increasing the weight difference between the first part 101 and the second part 102 and ensuring that the center of the main supporting shaft 1 is far away from the base 3.

In a specific implementation of this embodiment, in the extension direction of the main supporting axis 1, the length of the first part 101 is the same as the length of the second part 102, the first part 101 is a hollow structure, and the second part 102 is a solid structure, which improves the problem of base 3 offset.

In this embodiment, the plurality of support arms 2 extend radially outward from the main support axis 1 and extend in a direction away from the second portion 102, and the angle between each support arm 2 and the radial direction of the main support axis 1 is within a first threshold range.

In the conventional technology, the angle between the support arm 2 and the radial direction of the main support axis 1 is relatively large, which is also one of the reasons causing the displacement of the base 3. Comparing FIG. 1 and FIG. 2, in this embodiment, the angle between the support arm 2 and the radial direction of the main support axis 1 is reduced from a to b. In this embodiment, the angle between the support arm 2 and the radial direction of the main support axis 1 is reduced, thereby improving the problem of the displacement of the base 3.

In some implementations of the present embodiment, the first threshold value range is 0-30 degrees. For example, the angle between the support arm 2 and the radial direction of the main support axis 1 can be 0 degrees, 15 degrees or 20 degrees (in related technologies, the angle between the support arm 2 and the radial direction of the main support axis 1 is generally greater than 30 degrees).

In this embodiment, the plurality of support arms 2 extend radially outward from the main support axis 1 and are arranged to extend in a direction close to the second portion 102, and the angle between each support arm 2 and the radial direction of the main support axis 1 is within the second threshold range.

The supporting arm 2 can be extended in a direction away from the second portion 102 or in a direction close to the second portion 102. That is, if the base 3 is located above the main supporting axis 1, the supporting arm 2 can be extended obliquely upward or downward, as long as the center of gravity of the supporting structure of the base 3 is moved downward to improve the problem of the offset of the base 3.

In some implementations of this embodiment, the second threshold range is 0-60 degrees. For example, the angle b between the support arm 2 and the radial direction of the main support axis 1 can be 0 degrees, 30 degrees, 45 degrees or 60 degrees, refer to Figure 5.

In this embodiment, for example, a plurality of the support arms 2 are evenly arranged on the outer peripheral surface of the main support shaft 1.

The plurality of support arms 2 are evenly arranged on the outer peripheral surface of the main support shaft 1, which is beneficial to the uniform force of the base 3 during the rotation process, thereby avoiding the deviation of the base 3.

It should be noted that the number of the supporting arms 2 can be set according to actual needs. In some implementations of this embodiment, the base 3 supporting structure includes three supporting arms 2, and the angle between two adjacent supporting arms 2 is 120 degrees, but it is not limited to this.

The embodiment of the present invention also provides an epitaxial growth device, comprising: A reaction chamber 10 formed by two quartz bell jars arranged opposite to each other; A base 3, located in the reaction chamber 10, for supporting a silicon wafer; A heating structure 5, for providing heat to the reaction chamber 10; And the above-mentioned base 3 support structure.

Specifically, the epitaxial growth device includes a first quartz bell 6 and a second quartz bell 7, and the first quartz bell 6 and the second quartz bell 7 are surrounded by a mounting member to form a reaction chamber 10, and an air inlet is provided on one side of the reaction chamber 10, and an exhaust port is provided on the other side of the reaction chamber 10. The reaction chamber 10 is provided with a base 3 with a flat plate structure, and a preheating ring 4 is provided around the outer periphery of the base 3, and a gap is provided between the preheating ring and the base 3, and a gas channel is provided on one side of the preheating ring 4 close to the first quartz bell 6, and a base 3 support structure for supporting the base 3 is provided close to the second quartz bell 7.

A lifting shaft 8 is further provided on one side of the main supporting shaft 1 away from the base 3. A plurality of lifting arms 9 are provided at one end of the lifting shaft 8. The lifting arms 9 extend outwardly from the lifting shaft 8 along its radial direction and extend toward the base 3. A through hole is provided on the base 3. A plurality of lifting pins 11 are provided in the through hole. The plurality of lifting pins 11 correspond to the plurality of supporting arms 2 one by one. Each lifting pin 11 is arranged to pass through the through hole on the corresponding supporting arm 2, and a groove is arranged at one end of the lifting arm 9 away from the lifting shaft 8. An inserting portion capable of being inserted into the groove is arranged at one end of the lifting pin 11 away from the base 3. The lifting shaft 8 moves toward the direction approaching the base 3, thereby driving the lifting pin 11 to rise, thereby realizing the lifting of the silicon wafer carried on the base 3.

A heating structure 5 is also arranged outside the quartz bell jar, and the heating structure 5 can be a plurality of halogen lamps to provide heat.

The epitaxial growth method is described below: The multiple halogen lamps are turned on to raise the temperature of the reaction chamber 10 to 1100°C to 1150°C, and the silicon source gas is transported to the upper reaction chamber 10 through the gas inlet to grow an epitaxial layer on the silicon wafer; The silicon source gas passes through the front of the silicon wafer from the upper reaction chamber (the chamber between the base 3 and the first quartz bell 6), diffuses to the back of the silicon wafer and is discharged from the gap G of the reaction chamber 10 to the lower reaction chamber (the chamber between the base 3 and the second quartz bell 7), so that the thickness of the epitaxial layer grown on the silicon wafer is uniform; the reaction tail gas including the silicon source gas discharged to the lower reaction chamber 10 is discharged from the reaction chamber 10 through the gas exhaust port.

The above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. If the present invention is modified or replaced by something equivalent without departing from the spirit and scope of the present invention, it should be included in the protection scope of the patent application of the present invention.

1: Main support shaft 2: Support arm 3: Base 4: Preheating ring 5: Heating structure 6: First quartz bell 7: Second quartz bell 8: Lifting shaft 9: Lifting arm 10: Reaction chamber 11: Lifting pin 101: First part 102: Second part

FIG1 is a schematic diagram of the structure of an epitaxial growth device in the related technology; FIG2 is a schematic diagram of the structure of an epitaxial growth device in an embodiment of the present invention; FIG3 is a schematic diagram of the base support structure in an embodiment of the present invention; FIG4 is a schematic diagram of the thickness change of the epitaxial layer after the base is offset; FIG5 is a schematic diagram of the structure of an epitaxial growth device in an embodiment of the present invention.

2: Support arm

101: Part 1

102: Part 2

Claims (8)

A base support structure is used to support a base in an epitaxial growth device. The base support structure includes a main support shaft and a plurality of support arms extending outward from the main support shaft. The main support shaft includes a first part and a second part along its extension direction. The plurality of support arms are arranged on the first part. The weight of the first part is less than the weight of the second part. In the extension direction of the main support shaft, the length of the first part is greater than one third of the main support shaft. The base support structure as described in claim 1, wherein the first part is a hollow structure and the second part is a solid structure. The base support structure as described in claim 1, wherein the lengths of the first part and the second part are the same in the extension direction of the main support axis. The base support structure as described in claim 1, wherein a plurality of the support arms extend radially outward from the main support axis and extend away from the second portion, and the angle between each of the support arms and the radial direction of the main support axis is within a first threshold range, and the first threshold range is 0-30 degrees. The base support structure as described in claim 1, wherein a plurality of the support arms extend radially outward from the main support axis and are arranged in a direction close to the second portion, and the angle between each of the support arms and the radial direction of the main support axis is within a second threshold range, and the second threshold range is 0-60 degrees. The base support structure as described in claim 1, wherein a plurality of the support arms are evenly arranged on the outer peripheral surface of the main support shaft. The base support structure as described in claim 6 includes three support arms, and the angle between two adjacent support arms is 120 degrees. An epitaxial growth device, comprising: a reaction chamber surrounded by two quartz bell jars arranged opposite to each other; a base located in the reaction chamber and used to support a silicon wafer; a heating structure used to provide heat to the reaction chamber; and a base support structure as described in any one of claims 1 to 7.