KR101354784B1 - Susceptor - Google Patents

Abstract

Susceptor according to the invention, the first susceptor; And a second susceptor detachably provided with the first susceptor on an upper side of the first susceptor, wherein the first susceptor and the second susceptor are provided with a plurality of holes, and the first susceptor is formed. The separation distance between the holes of the susceptor and the separation distance between the holes of the second susceptor may be formed to be different from each other. As a result, the cost of maintaining the epitaxial reactor can be reduced, the effect of heat stress can be reduced, the yield of the device can be increased, and the susceptor can be used stably.

Description

Susceptor {Susceptor}

The present invention relates to a susceptor.

The cylindrical ingot grown by the Czochralski method is thinly cut into discs using a cutter, and then the surface is polished by a chemical mechanical method to make a thin wafer.

The type of the wafer is determined by the type and amount of the impurity added. When the n-type impurity such as phosphorus (P) or arsenic (Arsenic, As), which is a periodic group V material, is added, the wafer is an n-type wafer. When p-type impurities such as boron (B), a periodic group III material, are added, they are made into a p-type wafer. Impurities should be evenly distributed throughout the silicon wafer, and the resistance value of the substrate depends on the concentration of the impurity.

On the other hand, a process of forming a new high-purity crystal layer on the surface of a single crystal silicon wafer grown by the Czochralski method with a crystal orientation is called epitaxial growth or epitaxial method. The layer thus formed is referred to as an epitaxial layer or an epi-layer. Hereinafter, the method of depositing the epitaxial layer described above will be described in detail.

An epitaxial wafer is a wafer in which a thin single crystal layer is formed on a polished wafer used as a substrate by a chemical vapor deposition method of a reactor heated to a high temperature of about 1130 degrees Celsius (° C.). At this time, the chemical vapor deposition method induces phase transition from the gaseous phase to the solid phase, so that the fluid flow of the source gas, the material and model of the susceptor supporting the substrate wafer, and the energy of radically decomposing the source gas into radicals. The harmony of the circles is important. Especially for 300mm large diameter wafers, it is difficult to deposit a uniform epitaxial layer to the edge of the wafer, so the fluid flow and susceptor model of the gas in the reactor are important variables. For example, in a polished wafer which is heavily doped with n-type or p-type during the formation of the epitaxial wafer, the n-type or included in the polished wafer when the single crystal layer is formed by chemical vapor deposition. P-type ions move upward along the space between the wafer and the susceptor and are concentrated and doped at the edge of the wafer. Therefore, there is a problem that the newly grown single crystal layer is doped by an unwanted state. This problem is sometimes referred to as auto doping.

In addition, the wafer is covered with a native oxide layer before the epitaxial process is performed, so that the epitaxial layer of the polycrystalline is formed when the epitaxial process is performed. Therefore, the surface of the wafer is exposed to H 2 (hydrogen) gas at a high temperature of about 1150 ° C. to remove the natural oxide film. During this process, the native oxide film on the wafer surface is evenly removed, but the native oxide film is partially removed by the hydrogen gas introduced into the edge region and the space between the susceptor and the lift pins. Therefore, the rear surface of the mirrored wafer has a region where blurring is observed around the edge region and the lift pin due to uneven epitaxial layer growth. In addition, when the reaction gas is introduced between the wafer and the susceptor and is not exhausted when the wafer is loaded into the reactor and seated on the susceptor, a halo phenomenon occurs in the center portion of the wafer.

As described, autodoping and halo have a great influence on the quality of the wafer and the quality of the semiconductor chip. In order to improve this problem, the susceptor is made of a porous susceptor in which holes are formed, so that the material of the gap between the wafer and the susceptor can be smoothly discharged to the lower side of the susceptor.

However, in the case of using the porous susceptor, lamp heat is transferred to the wafer through the holes, creating thermal stress at the local location of the wafer. Due to the thermal stress, slip dislocation may occur and surface roughness may occur on the rear surface, thereby degrading nano quality of the wafer. In addition, areas with high thermal stress have a problem that leads to defects in the device process. The above-mentioned thermal stress is remarkably generated in the edge region of the wafer where heat transfer is not smooth. This problem is therefore sometimes referred to as edge stress. This phenomenon reduces the production yield of devices manufactured in the edge region of the wafer.

On the other hand, a wafer is placed in the susceptor, and heating operation is performed in this state. Therefore, if the susceptor wears out due to friction, and the silicon carbide coating film on the susceptor surface is damaged by friction in any small part, the entire susceptor must be replaced. Otherwise, foreign matters such as graphite to form a susceptor may be discharged and the epitaxial reactor may not operate properly. This problem acts as a problem of increasing the operating cost of the epitaxial reactor.

The present invention is proposed to improve the above problems, and improves the auto-doping phenomenon and halo phenomenon by using a porous susceptor, with the problem of heat stress and increase in maintenance costs due to wear of the susceptor We propose a susceptor that can improve our performance.

Susceptor according to the present invention for achieving the above object, the first susceptor; And a second susceptor detachably provided with the first susceptor on an upper side of the first susceptor, wherein the first susceptor and the second susceptor are provided with a plurality of holes, and the first susceptor is formed. The separation distance between the holes of the susceptor and the separation distance between the holes of the second susceptor may be formed to be different from each other.

According to the present invention, the cost of maintaining the epitaxial reactor can be reduced, the effect of thermal stress can be reduced, the production yield of the device can be increased, and the advantage of using the susceptor stably can be expected.

1 is a conceptual diagram of an epitaxial reactor according to an embodiment.
2 is a side cutaway view illustrating the configuration of a susceptor in detail.
3-6 show an embodiment of a contact of a susceptor.
7 illustrates the inclination angle of a hole provided in the susceptor.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the accompanying embodiments, and those skilled in the art who understand the spirit of the present invention can easily add, change, delete, add, etc. other components included in the scope of the same idea. It may be proposed, but this will also be included within the spirit of the present invention.

1 is a conceptual diagram of an epitaxial reactor according to an embodiment.

Referring to FIG. 1, a plurality of blades 5 for drawing the wafer 6 into and out of the reactor and a plurality of blades 5 are provided at positions spaced apart from each other to support the wafer 6 from the lower side when the blade 5 is taken out. The lift pin 1, the lift pin support shaft 2 serving to push up the leaf pin 1, the wafer 6 is placed upon operation of the reactor and the wafer is heated during the operation of the epitaxial reactor. A susceptor 31, 32 that performs an action, and a susceptor support shaft 4 that lifts and lowers the susceptor and is supported thereon are shown. Here, the susceptor 3 is divided into two separate parts, such that the first susceptor (see 31 in FIG. 2) forming a whole frame and the second susceptor placed on the first susceptor 31 are formed. (See 32 in FIG. 2).

The epitaxial reactor as described above operates in the following manner. When the conveying blade 5 carries the wafer 6 into the reactor, the lift pin 1 is lifted up to support the wafer 6 and supported, and the blade 5 is pulled out. The lift pin 1 then descends, and the wafer 6 is placed on the susceptor 31, 32 supported by the susceptor support shaft 4. After that, a series of processes for growing a single crystal film through a process such as heating the susceptor is performed.

2 is a side cross-sectional view illustrating the configuration of a susceptor according to the embodiment in detail.

Referring to FIG. 2, the susceptor 3 includes a second susceptor 32 provided so that the wafer 6 can be placed on an upper side thereof, and a second susceptor 32 supported from below. A first susceptor 31 provided is included. A lift pin hole (not shown) is provided in the susceptor 31 and 32 so that the lift pin 1 can move up and down. The first susceptor 31 may be provided with a seating portion 4 in a form recessed downward, and may be provided with a second susceptor 32 in the seating portion 4.

The susceptors 31 and 32 are provided with holes 33 and 34 to allow gas and the like to move freely below the susceptors 31 and 32. The holes 33 and 34 are provided to suppress autodoping and halo phenomenon. On the other hand, in order that the heat from the lamp (not shown) does not directly affect the wafer 6, it is preferable that the first hole 33 and the second hole 34 are provided in such a manner that they do not overlap each other. This can reduce the effects of heat stress. Of course, even if the holes 33 and 34 are provided to overlap each other, there is a possibility that they are slightly affected by the heat stress, but this is not impossible. In addition, when the angles or shapes of the holes 33 and 34 extend in the vertical direction are different from each other, even if the holes overlap each other, they may not be affected by thermal stress.

Fixing means for the second susceptor 32 may be provided so that the second susceptor 32 maintains its position at a predetermined position relative to the first susceptor 31. As the fixing means, a fixing pin 35 may be used. That is, the position of the susceptors 31 and 32 can be fixed by being fitted into the hole provided in the second susceptor 32 and the groove provided in the first susceptor 31. The fixing pin 35 may be provided as one, or two or more may be provided. The fixing pin 35 may be provided at the edge portion of the second susceptor 32. According to this positional relationship, the installation of the susceptor may be conveniently performed.

The second susceptor 32 is provided with a constant gap between the first susceptor 31. As a result, the gas discharged to the lower side of the second susceptor 32 may flow between the first susceptor 31 and the second susceptor 32. Of course, the gas flowing in the gap between the susceptors 31 and 32 may be discharged through the first susceptor 31. To this end, the contact portions of the susceptors 31 and 32 may be manufactured in a curved shape rather than a straight line.

3 to 6 show various examples in which the susceptors 31 and 32 maintain a constant distance from each other. In detail, FIG. 3 is a configuration in which the upper surface of the first susceptor 31 and the lower surface of the second susceptor 32 are convexly provided, respectively. According to this configuration, a space is formed in the gap so that gas can flow therein. 4 is a configuration in which the upper surface of the first susceptor 31 and the lower surface of the second susceptor 32 are respectively provided concave. Even in this configuration, a gap is generated between the susceptors 31 and 32 so that gas can flow. 5 is a configuration in which an upper surface of the first susceptor 31 forms a flat surface, and a lower surface of the second susceptor 32 is provided convexly, and FIG. 6 illustrates a top surface of the first susceptor 31 that is flat. The lower surface of the second susceptor 32 is concave. This configuration also provides a gap between the susceptors, so there is no problem with the flow of gas.

In addition, the bottom surface of the second susceptor 32 may be flat, and the top surface of the first susceptor 31 may be provided in a block or concave shape. Even in this case, the smooth flow of the reaction gas may provide an effect of suppressing auto-doping and halo and alleviating thermal stress.

The hole may have a certain size. As an example, the first hole 33 may have a size of 0.3 to 10 millimeters, and the second hole 34 may have a size of 0.3 to 1.5 millimeters. The smaller size of the second hole 34 compared to the first hole 33 is because the second hole 34 is provided directly on the lower surface of the wafer, so that the heat stress can be directly applied to the wafer. Has a purpose. In addition, the smaller the hole, the smaller the influence of the thermal stress, but the processing is difficult and the shape of the silicon carbide coating film is difficult, it is preferable not to exceed the above lower limit.

On the other hand, the position where the hole is provided may be formed from the inside of the 2 millimeters to the center of the susceptor with respect to the edge portion of the wafer in order to prevent auto-doping phenomenon. The area in which the hole is provided will be described in more detail. The first susceptor 31 may be provided in a radial width area of about 50 millimeters wide at the edge portion of the susceptor, and in the case of the second susceptor 32, may be provided in the entire area of the susceptor. As another example, the first susceptor 31 may be provided in a radius width region of about 80 millimeters wide at the edge portion of the susceptor, and in the case of the second susceptor 32 may be formed in a region of about 20 millimeters around the edge. have. According to such a configuration, there is no problem in the function of smoothly discharging gas between the region where the hole is provided in the first susceptor and the region where the hole is provided in the second susceptor.

On the other hand, the susceptors 31 and 32 are all described as being provided with holes, but embodiments in which no holes are formed in the susceptors 31 and 32 may be included in the spirit of the present invention. In such a case, although the effect by the discharge of gas cannot be obtained, only the second susceptor can be replaced and the first susceptor can be used as it is, without having to replace the aged susceptor as a whole. In this embodiment, only the second susceptor whose external object is frequently contacted and which mainly causes a failure is replaced, and the first susceptor does not need to be replaced, so that the maintenance cost of the equipment can be still reduced.

According to the configuration of the first susceptor 31 and the second susceptor 32 in the presence or absence of the hole and the position of the hole, the number of various cases shown in Table 1 may be presented. Inside each box of Table 1 mentioned above, the effect according to each embodiment is described.

division

Second susceptor No hole Whole hall Hall only in the center Hole only at the edge First susceptor

No hole * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor Whole hall * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control Hall only in the center * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control Hole only at the edge * Only second susceptor can be replaced
* Maintenance cost of epitaxial reactor * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control * Only second susceptor can be replaced
* Reduced maintenance cost of epitaxial reactor
* Auto Doping / Halo / Heat Stress Control

On the other hand, the holes 33 and 34, although the shape extending in the vertical direction is clear, the inclination angle implemented may be provided in various forms. 7 is a diagram illustrating an inclination angle.

Referring to FIG. 7, a second susceptor 82 is disposed above the first susceptor 81. Each susceptor 81, 82 is provided with a hole, which may be implemented at various inclination angles. As illustrated in the figure, A and a are vertical holes, B and b are holes having a sharp inclination angle, and C and c are holes with a gentle inclination angle. A hole having various inclination angles as described above may be provided. The angle of inclination of the hole of the second susceptor 82 indicated by the capital letter may be combined with any hole of the first susceptor 81 indicated by the lower case letter. However, in order to prevent the lamp row passing through the first susceptor 81 from passing through the second susceptor 82 and reaching the wafer 6, the inclination angle is different, or the hole and the upper surface of the first susceptor are formed. The way that the holes in the lower surface of the two susceptors do not coincide with each other may be applied.

The present invention may further include other embodiments. For example, the second susceptor may be fixed to the first susceptor rather than in a detachable form with respect to the first susceptor, so that the holes are not aligned with each other. In this case, the replacement of the second susceptor alone may be difficult, but the effect of reducing the effects of heat stress while suppressing autodoping and halo may be sufficiently obtained.

On the other hand, the size, density, and position of the holes provided in the susceptor are controllable using various variables of the process, and are not limited to the numerical values given in the examples.

According to the present invention, it is possible to control the auto-doping phenomenon and the halo phenomenon, while reducing the effects of heat stress. In addition, since only the second susceptor needs to be replaced as a part without replacing the entire susceptor, the maintenance cost of the epitaxial reactor is reduced. As a result, it is possible to proactively respond to the wafer industry, which is becoming more cost competitive.

31: the first susceptor
32: the second susceptor
33: first hall
34: second hall

Claims (12)

A first susceptor; And
A second susceptor detachably provided with the first susceptor above the first susceptor,
A plurality of holes are formed in the first susceptor and the second susceptor,
And a separation distance between the holes of the first susceptor and a separation distance between the holes of the second susceptor are different from each other. The method of claim 1,
The susceptor is formed so that the size of the opening overlapping the hole of the first susceptor and the hole of the second susceptor is different. The method of claim 1,
At least some of the first susceptor and the second susceptor are spaced apart. The method of claim 1,
The upper surface of the first susceptor and the lower surface of the second susceptor may be spaced apart from each other by a predetermined distance,
At least one of an upper surface of the first susceptor and a lower surface of the second susceptor is provided as a curved surface. 5. The method of claim 4,
At least one of an upper surface of the first susceptor and a lower surface of the second susceptor is a flat surface. The method of claim 1,
At least some of the first susceptor and the second susceptor are in contact with each other. The method of claim 1,
Susceptor comprising a fixing means for preventing the mutual shaking of the first susceptor and the second susceptor. The method of claim 7, wherein
The fixing means is a susceptor is a fixing pin which is supported together with the first susceptor and the second susceptor. The method of claim 1,
A susceptor having a hole provided in the first susceptor larger than a hole provided in the second susceptor. The method of claim 1,
At least a portion of an area where a hole provided in the first susceptor is provided and an area where a hole provided in the second susceptor is formed overlap each other. The method of claim 1,
The hole is inclined susceptor. The method of claim 1,
A susceptor recessed downward from an upper surface of the first susceptor, and includes a seating portion on which the second susceptor is placed.

Images