Base and device for epitaxial growth of silicon wafer

Abstract

The present invention provides a base and device for epitaxial growth of silicon wafers, belonging to the technical field of epitaxial growth of silicon wafers. The base for epitaxial growth of silicon wafers comprises: a disc-shaped supporting portion for supporting the silicon wafer; the disc-shaped supporting portion comprises at least one sector-shaped region and a spacing region other than the sector-shaped region; the sector-shaped region is spaced apart from the silicon wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, and the back of the fan-shaped region is thinned so that the thickness of the fan-shaped region is smaller than the thickness of the spacing region. The technical solution of the present invention can obtain an epitaxial silicon wafer with better flatness.

Description

Technical Field

[0001] The present invention relates to the technical field of epitaxial growth of silicon wafers, and in particular to a base and a device for epitaxial growth of silicon wafers. Background Art

[0002] The epitaxial growth process of silicon wafers is an important process in the semiconductor chip manufacturing process. This process refers to growing a silicon single crystal layer with controllable resistivity and thickness, no crystal native particles (COP) defects and no oxygen precipitation on the polished silicon wafer under certain conditions. The epitaxial growth of silicon wafers mainly includes vacuum epitaxial deposition, vapor phase epitaxial deposition and liquid phase epitaxial deposition, among which vapor phase epitaxial deposition is the most widely used.

[0003] 5For epitaxial growth of silicon wafers, flatness is an important indicator to measure the quality of epitaxial silicon wafers, and the flatness of epitaxial silicon wafers is directly related to the thickness of the epitaxial layer. During the epitaxial growth process, the temperature in the reaction chamber generated by the halogen lamp, the concentration of the silicon source gas, the flow rate of the silicon source gas, etc. will have a very obvious effect on the thickness of the epitaxial layer. In addition, the crystal orientation of the silicon wafer is another important factor that affects the thickness of the epitaxial layer and thus affects the flatness of the epitaxial silicon wafer. Summary of the invention

[0004] The present invention provides a base and a device for epitaxial growth of silicon wafers, which can obtain epitaxial silicon wafers with better flatness.

[0005] In order to achieve the above-mentioned object, the technical solution adopted in the embodiment of the present invention is: 5. A base for epitaxial growth of silicon wafers, comprising:

[0006] A disc-shaped carrying portion for carrying the silicon wafer;

[0007] The disc-shaped bearing portion includes at least one sector-shaped area and a spacing area other than the sector-shaped area, wherein the sector-shaped area is spaced apart from the silicon wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, and the back side of the fan-shaped region is thinned so that the thickness of the fan-shaped region is smaller than the thickness of the spacer region.

[0008] In some embodiments, the thickness of the fan-shaped region is <100> The radial direction corresponding to the crystal direction is adjacent to the silicon wafer. <100> Crystalline <110> The radial direction corresponding to the crystal orientation gradually increases.

[0009] In some embodiments, in a direction from the center to the edge of the disc-shaped supporting portion, the thickness of the base first decreases and then increases.

[0010] In some embodiments, the disc-shaped bearing portion includes four sector-shaped areas, and the spacing areas and the sector-shaped areas are arranged alternately.

[0011] In some embodiments, the four sector-shaped areas are all equal in size.

[0012] In some embodiments, the angle ratio between the spacing area and the fan-shaped area is 0.5:1-1.25:1.

[0013] In some embodiments, the difference between the thickness of the fan-shaped region and the thickness of the spacing region is 1-2 um.

[0014] In some embodiments, the radius of the fan-shaped area is smaller than the radius of the base.

[0015] The embodiment of the present invention further provides a device for epitaxial growth of silicon wafers, comprising:

[0016] the above-mentioned base;

[0017] A reaction chamber for accommodating the base, wherein the base divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the silicon wafer is placed in the upper reaction chamber;

[0018] a gas inlet for delivering a silicon source gas into the upper reaction chamber to grow an epitaxial layer on the silicon wafer;

[0019] An exhaust port for discharging reaction tail gas generated by epitaxial growth out of the reaction chamber.

[0020] The beneficial effects of the present invention are:

[0021] In this embodiment, when the silicon wafer is placed in the base, the inclined surface supports the silicon wafer. At the location where the base is thick, the heat transfer loss is large, so that the reaction temperature of the silicon wafer at the corresponding location is reduced, the reaction speed is slowed down, and the thickness of the epitaxial layer generated per unit time is reduced; at the location where the base is thin, the heat transfer loss is small, so that the reaction temperature of the silicon wafer at the corresponding location is increased, the reaction speed is accelerated, and the thickness of the epitaxial layer generated per unit time is increased. <110> The growth rate of the epitaxial layer in the crystal direction is greater than <100> The growth rate of the epitaxial layer in the crystal direction, and <100> The growth rate of the epitaxial layer in the crystal direction is the lowest. Therefore, in this embodiment, a fan-shaped area is designed in the disc-shaped supporting part, and the fan-shaped area is aligned with the silicon wafer. <100> The radial direction corresponding to the crystal direction is the central axis, and the thickness of the fan-shaped area is less than the thickness of the spacing area, so that the base and <100> The thickness at the position corresponding to the crystal direction is thinner, which increases the growth rate of the epitaxial layer at this position, thereby obtaining an epitaxial silicon wafer with better flatness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Represents silicon wafer <110> Crystal orientation and <100> Schematic diagram of crystal orientation;

[0023] Figure 2 A schematic diagram showing the thickness of the epitaxial layer of a silicon wafer;

[0024] Figure 3 A schematic top view showing a base for epitaxial growth of a silicon wafer according to an embodiment of the present invention;

[0025] Figure 4 A schematic cross-sectional view of a base in the AA direction according to an embodiment of the present invention is shown;

[0026] Figure 5 A schematic cross-sectional view of a base in the BB direction according to an embodiment of the present invention is shown;

[0027] Figure 6 A schematic cross-sectional view of a base in the CC direction according to an embodiment of the present invention is shown;

[0028] Figure 7 A schematic cross-sectional view of a base in the DD direction according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0030] The crystal orientation of the silicon wafer affects the thickness of the epitaxial layer. Figure 1 , Figure 1 Taking the silicon wafer W100 with (100) crystal plane as an example, the crystal orientation of the silicon wafer is shown. Figure 1 As shown, if the three o'clock direction of the silicon wafer W100 is the radial direction of 0° / 360° and <110> If the crystal direction is 0° / 360°, the radial directions of 90°, 180° and 270° clockwise relative to the radial direction of 0° / 360° are also the radial directions of silicon wafer W100. <110> The radial directions of 45°, 135°, 225° and 315° rotated clockwise relative to the radial direction of 0° / 360° are the crystal directions of silicon wafer W100. <100> That is to say, for the silicon wafer W100, the four <110> The crystal orientation corresponds to the four radial directions distributed at 90° intervals along the circumference of the silicon wafer. <100> The crystal directions also correspond to the four radial directions distributed at 90° intervals along the circumference of the silicon wafer, and the adjacent <110> Crystal orientation and <100> The crystal directions are spaced 45° apart along the circumference of the silicon wafer.

[0031] See also Figure 2 , Figure 2 In the case of using a conventional susceptor for epitaxial growth of silicon wafers, as shown in FIG. Figure 1 The epitaxial layer thickness (EPI Layer Thickness) results of the silicon wafer W100 with a diameter of 300 mm at a position 3 mm away from the radial edge are shown in FIG.

[0032] exist Figure 2 The horizontal axis represents Figure 1 The radial angle of the silicon wafer W100 is shown in FIG. 1 , and the ordinate represents the epitaxial layer thickness value (in um) of the silicon wafer W100 at the corresponding angle position. Figure 2 As shown in FIG. 1 , the thickness of the epitaxial layer grown on the silicon wafer W100 is at a peak value in the radial directions of 45°, 135°, 225° and 360 / 0°. That is, the thickness of the epitaxial layer grown on the silicon wafer W100 is at a peak value in the radial directions of 45°, 135°, 225° and 360 / 0°. <110> The growth rate of the epitaxial layer in the radial direction is the largest; from the radial directions of 45°, 135°, 225° and 315° to the radial directions of 0 / 360°, 90°, 180° and 270°, the thickness of the epitaxial layer grown on the silicon wafer W100 gradually decreases, that is, the growth rate of the silicon wafer W100 decreases from <110> Crystal to <100> The crystal direction gradually decreases, which is also Figure 1 The arrows are shown in the figure, where the direction of the arrows indicates the direction of decreasing growth rate; in the radial directions of 0 / 360°, 90°, 180° and 270°, the thickness of the epitaxial layer grown on the silicon wafer W100 is a valley value, that is, the thickness of the epitaxial layer grown on the silicon wafer W100 is a valley value. <100> The growth rate of the crystal direction is the smallest. And as is known in the prior art, the above-mentioned thickness difference is more obvious in the region closer to the radial edge of the silicon wafer.

[0033] An existing measure to improve the flatness of epitaxial silicon wafers is to deliver etching gas used to prevent the deposition of epitaxial layers into the reaction chamber through an air inlet, and when the silicon wafer rotates with the susceptor, when the faster growing area of ​​the silicon wafer passes through the air inlet, the air intake rate increases, and when the slower growing area of ​​the silicon wafer passes through the air inlet, the air intake rate decreases. However, during the epitaxial growth of silicon wafers, it is inevitable to change process parameters such as the rotation speed of the susceptor. In this case, the change in the air intake rate needs to be changed accordingly with the change in the rotation speed, which increases the complexity of the process.

[0034] Another existing measure to improve the flatness of epitaxial silicon wafers is to add a heat-conducting block to the bottom surface of the base to change the temperature of the corresponding area to achieve the purpose of improving the flatness of the silicon wafer. However, since the thickness of the area where the heat-conducting block is installed in the base is relatively small, usually less than 3 mm, the installed heat-conducting block will cause load-bearing problems for the base, affecting the service life of the base. On the other hand, the heat-conducting block will change the temperature of the corresponding area other than the area where it is installed, so that the local morphology of the epitaxial silicon wafer finally obtained is affected, and in severe cases, the silicon wafer will be dislocated due to uneven stress.

[0035] In order to solve the above technical problems, an embodiment of the present invention provides a base and a device for epitaxial growth of silicon wafers, which can obtain epitaxial silicon wafers with better flatness.

[0036] The embodiment of the present invention provides a base for epitaxial growth of silicon wafers, such as Figure 3 As shown, including:

[0037] A disc-shaped carrying portion 10 for carrying the silicon wafer;

[0038] The disc-shaped bearing portion 10 includes at least one sector-shaped area (S1-S4) and a spacing area other than the sector-shaped area. The sector-shaped area is spaced apart from the silicon wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, and the back side of the fan-shaped region is thinned so that the thickness of the fan-shaped region is smaller than the thickness of the spacer region.

[0039] In this embodiment, when the silicon wafer is placed in the base, the inclined surface supports the silicon wafer. At the location where the base is thick, the heat transfer loss is large, so that the reaction temperature of the silicon wafer at the corresponding location is reduced, the reaction speed is slowed down, and the thickness of the epitaxial layer generated per unit time is reduced; at the location where the base is thin, the heat transfer loss is small, so that the reaction temperature of the silicon wafer at the corresponding location is increased, the reaction speed is accelerated, and the thickness of the epitaxial layer generated per unit time is increased. <110> The growth rate of the epitaxial layer in the crystal direction is greater than <100> The growth rate of the epitaxial layer in the crystal direction, and <100> The growth rate of the epitaxial layer in the crystal direction is the lowest. Therefore, in this embodiment, a fan-shaped area is designed in the disc-shaped supporting part, and the fan-shaped area is aligned with the silicon wafer. <100> The radial direction corresponding to the crystal direction is the central axis, and the thickness of the fan-shaped area is less than the thickness of the spacing area, so that the base and <100> The thickness at the position corresponding to the crystal direction is thinner, which increases the growth rate of the epitaxial layer at this position, thereby obtaining an epitaxial silicon wafer with better flatness.

[0040] Since silicon <110> Crystal orientation to silicon wafer <100> In the direction of the crystal direction, the growth rate of the epitaxial layer gradually decreases. Therefore, in this embodiment, the thickness of the fan-shaped region increases from the thickness of the silicon wafer to the thickness of the fan-shaped region. <100> The radial direction corresponding to the crystal direction is adjacent to the silicon wafer. <100> Crystalline <110> The radial direction corresponding to the crystal orientation gradually increases, so that the reaction temperature of the silicon wafer can correspond to the growth rate of the epitaxial layer, thereby achieving the purpose of controlling the flatness of the epitaxial layer.

[0041] In some embodiments, in order to ensure the support strength and thickness stability of the base, the thickness of the base first decreases and then increases from the center to the edge of the disc-shaped bearing portion.

[0042] In a specific example, Figure 4 As shown, in the AA direction, at a position close to the edge of the base, the thickness d1 may be 3.83 um, at a position close to the center of the base, the thickness d3 may be 2.38 um, and at a position between the center of the base and the edge of the base, the thickness d2 may be 2.71 um.

[0043] like Figure 5 As shown, in the fan-shaped area S1, in the BB direction, at the position close to the edge of the base, the thickness d4 can be 3.83um, in the direction from the edge of the base to the center of the base, the thickness d5 can be 2.12um, the thickness d6 can be 1.93um, and to ensure the strength of the bottom of the base, the center thickness d7 can be 2.38um, and the thickness d8 can be 1.97um.

[0044] like Figure 6 and Figure 7 As shown, in the sector area S1, the circumference in the CC direction is 57.46um, and the thickness d9 of the base in the CC direction is 2.47um; the circumference in the DD direction is 87.16um, and the thickness d10 of the base in the DD direction is 2.58um, that is, the closer to the edge of the base, the greater the thickness of the sector area.

[0045] In some embodiments, Figure 3 As shown, since the silicon wafer consists of four <100> Therefore, the disc-shaped supporting part 10 includes four fan-shaped areas: S1, S2, S3 and S4, and the spacer areas and the fan-shaped areas are arranged alternately. <100> The thickness at the position corresponding to the crystal direction is thinner, which increases the growth rate of the epitaxial layer at this position, thereby obtaining an epitaxial silicon wafer with better flatness.

[0046] In some embodiments, Figure 3 As shown, the four sector-shaped areas S1, S2, S3 and S4 are all equal in size.

[0047] In some embodiments, the angle ratio between the spacing area and the fan-shaped area is 0.5:1-1.25:1.

[0048] In this embodiment, the angle of the fan-shaped area can be 30-50°. For example, the angle of the fan-shaped area can be 30°, and correspondingly, the angle of the spacing area is 60°; the angle of the fan-shaped area can be 40°, and correspondingly, the angle of the spacing area is 50°; the angle of the fan-shaped area can be 50°, and correspondingly, the angle of the spacing area is 40°.

[0049] When the angle ratio between the spacing area and the fan-shaped area is 0.5:1-1.25:1, the silicon wafer can be <110> The growth rate of the epitaxial layer in the crystal direction is <100> The growth rates of the epitaxial layers in the crystal directions are close, which is beneficial to improving the flatness of the epitaxial layers.

[0050] In some embodiments, the difference between the thickness of the fan-shaped region and the thickness of the spacer region is 1-2 um. This ensures that during epitaxial growth, the reaction temperature of the silicon wafer in the fan-shaped region is substantially consistent with the reaction temperature of the silicon wafer in the spacer region, which is beneficial to improving the thickness uniformity of the epitaxial layer.

[0051] In a specific example, Figure 3 As shown, the radius of the fan-shaped area is smaller than the radius of the base. This is because during epitaxial growth, the silicon wafer is generally only placed in the central area of ​​the base, and the orthographic projection of the silicon wafer on the base does not cover the edge of the base. The thickness of the edge of the base does not affect the growth rate of the epitaxial layer. Therefore, there is no need to thin the thickness of the edge of the base, which can ensure the support strength and thickness stability of the base.

[0052] The embodiment of the present invention further provides a device for epitaxial growth of silicon wafers, comprising:

[0053] the above-mentioned base;

[0054] A reaction chamber for accommodating the base, wherein the base divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the silicon wafer is placed in the upper reaction chamber;

[0055] a gas inlet for delivering a silicon source gas into the upper reaction chamber to grow an epitaxial layer on the silicon wafer;

[0056] An exhaust port for discharging reaction tail gas generated by epitaxial growth out of the reaction chamber.

[0057] In addition, like the existing device for epitaxial growth of silicon wafer W, the device can also include: a base support frame, an upper quartz bell jar and a lower quartz bell jar that together enclose a reaction chamber, a plurality of heating bulbs, mounting components, etc., and there is also a small gap between the radial edge of the base and adjacent components so that the base can be driven by the base support frame to rotate around the central axis at a certain speed, which will not be repeated here.

[0058] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments, since they are basically similar to the product embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the product embodiments.

[0059] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0060] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” or “under” another element, it can be “directly on” or “under” the other element or intervening elements may be present.

[0061] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0062] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A susceptor for epitaxial growth of silicon wafers, characterized in that: include: A disc-shaped carrying portion for carrying the silicon wafer; The disc-shaped bearing portion includes at least one sector-shaped area and a spacing area other than the sector-shaped area, wherein the sector-shaped area is spaced apart from the silicon wafer. <100> The radial direction corresponding to the crystal direction is the central axis, and the back side of the fan-shaped region is thinned so that the thickness of the fan-shaped region is smaller than the thickness of the spacer region; The thickness of the fan-shaped region is from <100> The radial direction corresponding to the crystal direction is adjacent to the silicon wafer. <100> Crystalline <110> The radial direction corresponding to the crystal orientation gradually increases; From the center to the edge of the disc-shaped bearing portion, the thickness of the base first decreases and then increases; The difference between the thickness of the fan-shaped area and the thickness of the spacing area is 1-2 um, and the radius of the fan-shaped area is smaller than the radius of the base.

2. The base according to claim 1, characterized in that: The disc-shaped bearing portion includes four sector-shaped areas, and the spacing areas and the sector-shaped areas are arranged alternately.

3. The base according to claim 2, characterized in that: The sizes of the four sector-shaped areas are all equal.

4. The base according to claim 2, characterized in that: The angle ratio between the spacing area and the fan-shaped area is 0.5:1-1.25:

1.

5. A device for epitaxial growth of silicon wafers, characterized in that: include: A base according to any one of claims 1 to 4; A reaction chamber for accommodating the base, wherein the base divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the silicon wafer is placed in the upper reaction chamber; a gas inlet for delivering a silicon source gas into the upper reaction chamber to grow an epitaxial layer on the silicon wafer; An exhaust port for discharging reaction tail gas generated by epitaxial growth out of the reaction chamber.

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