JP7619257B2 - Substrate placement table and film forming apparatus - Google Patents

Description

This disclosure relates to a substrate mounting table and a film forming apparatus used in the manufacture of semiconductor devices.

Patent Document 1 discloses the configuration of a CVD film formation apparatus. When a film is formed on a substrate using a CVD film formation apparatus, reactants are deposited on the surface area of the mounting table even in areas where the substrate is not placed. Meanwhile, due to problems with the accuracy of the transport device, the substrate may be placed in an offset position during transport.

JP 2005-142529 A

When the substrate is placed in an offset position, part of the substrate rides on the accumulated reactants, forming a gap between the substrate and the mounting table. This causes problems such as uneven film formation due to uneven temperature distribution on the substrate, or film formation on the back side of the substrate due to reactants getting around. To maintain the quality of the film formation, it is necessary to perform maintenance to replace the mounting table and surrounding parts before this problem occurs. However, frequent maintenance can lead to issues such as reduced production efficiency due to equipment shutdowns during operation, and quality fluctuations due to changes in the chamber environment before and after operation.

In order to solve the above-mentioned problems, Patent Document 1 discloses technology relating to a mounting table having a recess along the outer periphery of the position where the substrate is placed. With this configuration, the reactants are first deposited in the recess, so it is possible to extend the time before problems occur due to the deposited reactants compared to conventional methods. However, this configuration does not take into consideration the prevention of the deposition of reactants on the mounting table itself, and there is room for improvement in this regard.

Therefore, the present disclosure aims to provide a substrate mounting table and a film formation apparatus that can reduce the frequency of maintenance by suppressing the deposition of reactants on the surface of the substrate mounting table during film formation.

A first aspect of the present disclosure is preferably a substrate mounting table comprising a wafer suction portion and a susceptor supporting the wafer suction portion, the wafer suction portion having a first circular plane on which a substrate is placed and a second circular plane in contact with the susceptor, the diameter of the first circular plane being larger than the diameter of the second circular plane, the susceptor having a susceptor peripheral portion which is a region excluding the region in contact with the second circular plane, and the susceptor peripheral portion comprising a concentric region having an inner circumference that is the periphery of the second circular plane and which is thinner than the region in contact with the second circular plane .
Moreover, a second aspect of the present disclosure is preferably a film formation apparatus comprising a substrate mounting table and a guide ring, the substrate mounting table comprising a wafer suction portion and a susceptor supporting the wafer suction portion, the wafer suction portion having a first circular plane for mounting the substrate and a second circular plane in contact with the susceptor, the diameter of the first circular plane being larger than the diameter of the second circular plane, the guide ring having an extension portion at the periphery of the susceptor covering the surface on the wafer suction portion side, and the tip of the extension portion being tapered so that its thickness decreases toward the center of the susceptor .

According to the first and second aspects of the present disclosure, it is possible to suppress deposition of reactants on the surface of the substrate during film formation, thereby enabling the quality of the thin film to be maintained for a longer period of time than in the conventional configuration, and thus reducing the frequency of maintenance.

1 is a diagram showing a structure inside a chamber of a film forming apparatus according to a first embodiment of the present disclosure; 2 is a diagram showing a configuration of an upper portion of the device according to the first embodiment of the present disclosure. FIG. FIG. 3 is an enlarged view of a portion of FIG. 2 . FIG. 11 is a diagram showing the configuration of the upper part of an apparatus according to a second embodiment of the present disclosure. FIG. 5 is an enlarged view of a portion of FIG. 4 . FIG. 13 is a diagram showing the configuration of the upper part of an apparatus according to a third embodiment of the present disclosure. FIG. 7 is an enlarged view of a portion of FIG. 6. FIG. 13 is a diagram showing the configuration of the upper part of an apparatus according to a fourth embodiment of the present disclosure. FIG. 9 is an enlarged view of a portion of FIG. 8 .

First embodiment
1 is a diagram showing the internal structure of a chamber of a film formation apparatus according to a first embodiment of the present disclosure. The film formation apparatus of the present disclosure has an apparatus main body as the chamber.

The gas head 1 is installed at the bottom of the device and introduces gas into the chamber during film formation processing. Unused gas introduced from the gas head 1 is exhausted through exhaust piping 9. A wafer W is placed facing the gas head 1 with its surface facing down. At this time, the wafer W is attracted to a suction hole in the center of the wafer suction unit 4, which is connected to the suction line 8. The suction line 8 functions as a suction path for vacuum suction and passes through the center of the wafer suction unit 4, the susceptor 3, and the heater unit 2.

The wafer suction part 4 is supported by the susceptor 3. The susceptor 3 is in contact with the guide ring 5. The guide ring 5 is supported by the guide 6 and prevents film formation on the heater unit 2. The guides 6 and 7 raise the susceptor 3 and guide ring 5 and attach them to the heater unit 2, transferring heat from the heater unit 2. The drive unit 10 at the top of the device moves the substrate parallel within the chamber during film formation processing.

During the film formation process, if the area of the susceptor 3 other than the area in contact with the wafer suction part 4 is the susceptor peripheral part 3a, then film formation is also performed on the surface of the susceptor peripheral part 3a and the guide ring 5. On the other hand, due to the accuracy of the transport device, the substrate may be placed in a misaligned position during substrate transport. Then, when the film adhering to the susceptor peripheral part 3a becomes thicker than the height of the wafer suction part 4, the substrate may ride up on the film adhering to the susceptor peripheral part 3a. In this case, a gap is formed between the substrate and the wafer suction part 4, which causes the temperature distribution of the substrate to become uneven, resulting in uneven film formation or film formation on the back surface of the wafer W. Therefore, it is necessary to perform regular maintenance for susceptor replacement beforehand. Maintenance requires labor hours, such as returning the device to atmospheric conditions in addition to replacing parts, and the device state may change before and after replacement, which may affect the film quality, so it is ideal to perform it as infrequently as possible.

Another factor that may require maintenance is the spherical products that form near the outer periphery of the susceptor peripheral portion 3a. Because the center of the susceptor 3 is heated by the heater unit 2, the temperature is lower the closer to the outer periphery. As a result, reactants that become a film near the boundary between the susceptor 3 and the wafer adsorption portion 4 become spherical products near the outer periphery of the susceptor 3 due to insufficient thermal reaction. The more films are formed, the larger these products become, and they may come into contact with the gas head 1 and cause dust, or fall from the susceptor 3, causing contamination inside the chamber.

In order to suppress the generation of these spherical products, a guide ring 5 made of foamed quartz and having a mesh structure is used. The guide ring 5 prevents the generation of spherical products on its surface by adhering the reactants inside the mesh. If products accumulate inside the guide ring 5, the above-mentioned effect will be weakened, making regular maintenance to replace the guide ring necessary, but it is ideal to keep this frequency low for the same reasons as for replacing the susceptor.

As described above, in order to reduce the frequency of maintenance, it is important to suppress the generation of products on the entire surface of the susceptor peripheral portion 3a during the film formation process. An embodiment that can achieve this is described below.

Figure 2 is a diagram showing the configuration of the upper part of the apparatus according to the first embodiment of the present disclosure, and Figure 3 is an enlarged view of Figure 2. The film forming apparatus of this embodiment 1 is equipped with a wafer suction part 11 having a first circular plane 11a on which a substrate is placed and a second circular plane 11b connected to a susceptor 3, and the diameter of the first circular plane 11a is larger than the diameter of the second circular plane 11b.

With this configuration, reactants that accumulate on the susceptor periphery 3a during the film formation process are redirected around the boundary between the wafer suction section 11 and the susceptor 3, dispersing the reactants' adhesion locations more than with conventional configurations. As a result, the overall film formation speed of the thin film formed on the susceptor periphery 3a is slowed down, extending the time until the quality of the film formation deteriorates and reducing the frequency of maintenance.

The configuration of the film formation apparatus in the following embodiments will be described with a focus on the differences from embodiment 1. Note that although this embodiment shows a case where an oxide film is formed using an atmospheric pressure CVD apparatus, a different method or a film formation apparatus using a different film type may be used. Also, although this embodiment shows a case where the substrate is formed using silicon, it may be formed using a wide band gap semiconductor that has a larger band gap than silicon. Examples of wide band gap semiconductors include silicon carbide, gallium nitride-based materials, and diamond.

Embodiment 2
4 is a diagram showing the configuration of the upper part of the apparatus according to the second embodiment of the present disclosure, and FIG. 5 is an enlarged view of FIG. 4. In addition to the wafer suction part 11, the film forming apparatus according to the second embodiment includes a susceptor 12 having a concentric region with the periphery of the second circular flat surface 11b of the wafer suction part 11 as the inner circumference, the region being thinner than the region in contact with the second circular flat surface 11b. FIGS. 4 and 5 show the susceptor 12 in which a concave groove 13 is formed by thinning a part of the thickness. Note that the susceptor 12 does not have to be shaped to include the concave groove 13, and the entire region not in contact with the second circular flat surface 11b may be thinner than the region in contact with the second circular flat surface 11b.

With this configuration, reactants that have accumulated around the susceptor periphery 12a during the film formation process are transported not only to the boundary between the wafer suction portion 11 and the susceptor 12, but also to the concave groove 13. This disperses the locations where reactants adhere, slowing down the overall film formation speed of the thin film formed around the susceptor periphery 12a. As a result, the time until film formation becomes ununiform can be extended, and maintenance frequency can be reduced.

Embodiment 3
Fig. 6 is a diagram showing the configuration of the upper part of the apparatus according to the third embodiment of the present disclosure, and Fig. 7 is an enlarged view of Fig. 6. In addition to the wafer suction part 11, the film forming apparatus of the third embodiment includes a guide ring 14 that extends from the periphery of the susceptor 3 so as to cover the surface on the wafer suction part 11 side.

This configuration allows the reactants that adhere to the outer periphery of the susceptor peripheral portion 3a during the film formation process to instead adhere to the inside of the guide ring 14. As a result, spherical products are less likely to be generated around the susceptor peripheral portion 3a, which reduces the frequency of maintenance.

Fourth embodiment
Fig. 8 is a diagram showing the configuration of an upper portion of the apparatus according to the fourth embodiment of the present disclosure, and Fig. 9 is an enlarged view of Fig. 8. In addition to the wafer suction part 11, the film forming apparatus of the fourth embodiment includes a guide ring 15 that extends from the periphery of the susceptor 3 so as to cover the surface on the wafer suction part 11 side, and the tip of the extension is tapered so as to become thinner toward the center of the susceptor 3.

This configuration has the same effect as in embodiment 3, making it difficult for spherical products to be generated. In addition, the tapered shape of the guide ring 15 has a gas straightening effect, so it is expected that the film deposition on the peripheral portion 3a of the susceptor will be uniform. These two points make it possible to reduce the frequency of maintenance.

3 susceptor, 3a susceptor periphery, 4 wafer suction part, 5 guide ring, 8 suction line, 11 wafer suction part, 11a first circular plane, 11b second circular plane, 12 susceptor, 12a susceptor periphery, 14 guide ring, 15 guide ring

Claims (7)

a wafer suction part; and a susceptor supporting the wafer suction part,
The wafer suction unit includes:
a first circular plane on which a substrate is placed;
a second circular plane in contact with the susceptor;
the diameter of the first circular plane is greater than the diameter of the second circular plane;
the susceptor has a susceptor periphery that is a region excluding a region in contact with the second circular plane,
The susceptor peripheral portion includes a concentric region having an inner circumference on the periphery of the second circular flat surface, the concentric region being thinner than a region in contact with the second circular flat surface.
Substrate placement stand. The substrate mounting table according to claim 1 , wherein the wafer suction portion includes a suction line that functions as a suction path for suction-fixing the substrate. Equipped with a substrate placement table and guide ring,
the substrate mounting table includes a wafer suction portion and a susceptor that supports the wafer suction portion,
The wafer suction unit includes:
a first circular plane on which a substrate is placed;
a second circular plane in contact with the susceptor;
the diameter of the first circular plane is greater than the diameter of the second circular plane;
the guide ring has an extension portion that covers a surface of the susceptor on a side of the wafer suction portion at a periphery of the susceptor,
The tip of the extension is tapered so that the thickness decreases toward the center of the susceptor.
Film forming equipment. The film forming apparatus according to claim 3 , wherein the wafer suction section includes a suction line that functions as a suction path for suction-fixing the substrate. 2. The substrate mounting table according to claim 1,
The wafer suction portion suctions the substrate formed of a wide band gap semiconductor. The wafer suction portion suctions the substrate formed of a wide band gap semiconductor.
The film forming apparatus according to claim 3 . 7. The film forming apparatus according to claim 5, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material or diamond.

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