CN114097072A

CN114097072A - Wafer bearing disc and wafer epitaxial equipment

Info

Publication number: CN114097072A
Application number: CN201980098322.5A
Authority: CN
Inventors: 刘凯; 程凯
Original assignee: Enkris Semiconductor Inc
Current assignee: Enkris Semiconductor Inc
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2022-02-25
Anticipated expiration: 2039-07-10
Also published as: WO2021003705A1; CN114097072B

Abstract

The invention provides a wafer bearing disc and wafer epitaxial equipment, and relates to the technical field of chemical deposition devices, wherein the wafer bearing disc comprises a disc body and a groove; a flow guide surface is arranged at the edge of the notch of the groove; wherein the flow guide surface is obliquely arranged relative to the wafer and extends from the notch of the groove to the direction of the groove bottom. The wafer bearing disc relieves the technical problem of poor epitaxial layer deposition quality at the edge of the wafer, and achieves the purpose of improving the epitaxial deposition quality at the edge of the wafer.

Description

Wafer bearing disc and wafer epitaxial equipment

Technical Field

The invention relates to the technical field of chemical deposition devices, in particular to a wafer bearing disc and wafer epitaxial equipment.

Background

In a conventional thin film manufacturing process, for example, Metal-organic Chemical Vapor Deposition (MOCVD), a wafer carrier is usually placed in a reaction container, a wafer substrate is placed in a groove of the wafer carrier, then various reaction gases are introduced into the reaction container, and the reaction gases flow from the center of the wafer carrier to the periphery of the wafer carrier, so as to form a thin film layer on the surface of the wafer substrate.

The wafer carrier disc used in the prior art can cause that reaction gas can not be effectively deposited at the edge of a wafer, so that the difference exists between the epitaxial layer at the edge of the wafer and the epitaxial layers at other positions of the wafer, the epitaxial deposition quality at the edge of the wafer is poor, and the yield of products is reduced.

In view of the above problems, the following technical solutions are proposed.

Disclosure of Invention

A first objective of the present invention is to provide a wafer carrier to alleviate the problem of poor epitaxial deposition effect at the edge of a wafer when epitaxial deposition is performed by using the wafer carrier in the prior art.

A second object of the present invention is to provide a wafer epitaxy apparatus comprising the above wafer carrier tray.

In order to achieve the purpose, the following technical scheme is adopted:

a wafer carrier tray comprising:

a tray body;

the groove is arranged on the tray body;

and the flow guide surface is arranged on the side wall of the disc body, is arranged at the position of the reaction gas inlet and is obliquely arranged relative to the wafer.

Further, the height H of the flow guide surface is more than or equal to H₁-H ₂And the height H of the flow guide surface is less than or equal to H₁；

Wherein H₁Is the depth of the groove H₂Is the wafer thickness.

Further, the side wall of the groove is perpendicular to the bottom surface of the groove.

Further, the angular range of the central angle of the flow guide surface corresponding to the circumferential arc length of the groove is not greater than 180 °, and preferably, the angular range is not greater than 120 °.

A wafer epitaxial device comprises the wafer bearing disc.

Compared with the prior art, the invention has the following beneficial effects:

in the wafer bearing disc provided by the invention, the edge of the notch of the groove is provided with a flow guide surface; because the flow guide surface is obliquely arranged relative to the wafer, reaction gas firstly contacts with the edge of the wafer arranged in the groove after flowing through the flow guide surface during epitaxy, and then flows to other parts of the wafer from the edge of the wafer corresponding to the flow guide surface.

In the process that the reaction gas flows into the groove, the arrangement of the flow guide surface changes the flow direction of the reaction gas, so that the flow direction of the reaction gas is changed from the incident direction which is originally parallel to the surface of the wafer to the obliquely downward blowing direction to the wafer, and the reaction gas is firstly contacted with the edge of the wafer and then flows to the gas part of the wafer. Because the change of the gas flow direction of the reaction gas increases the contact probability of the reaction gas and the edge of the wafer, the epitaxial deposition quality of the edge of the wafer is improved, the epitaxial deposition quality of the edge of the wafer is more consistent with the epitaxial deposition quality of other positions of the wafer, and the yield of the epitaxial process of the wafer is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIGS. 1a-1b are schematic top views of wafer carriers according to the prior art;

FIG. 2 is an enlarged schematic view of the cross-sectional structure of FIG. 1b taken along line A-A' of FIG. 1 a;

FIGS. 3a-3c are schematic top views of wafer carriers according to embodiments of the present invention;

FIG. 4 is an enlarged schematic view of the cross-sectional structure of FIG. 3c at structure A-A';

FIG. 5 is a cross-sectional view taken along line A-A' of another embodiment of a wafer carrier platter of the structure shown in FIGS. 3a-3 b;

FIG. 6 is a schematic cross-sectional view taken along line A-A' of another embodiment of a wafer carrier having the structure shown in FIGS. 3a-3 b;

FIG. 7 is a cross-sectional view taken along line A-A' of another embodiment of a wafer carrier platter of the structure illustrated in FIGS. 3a-3 b;

fig. 8 is a schematic view of the arrangement position of the flow guide surface when the wafer carrier tray rotates counterclockwise;

fig. 9 is a schematic top view of a wafer carrier according to another embodiment of the present invention.

Icon: 10-a tray body; 30-a wafer; 20-grooves; 40-step; 21-a flow guide surface; 23-diversion trenches; curve 31-reactant gas flow direction; h-height difference between the groove and the wafer; h-height of the flow guide surface; h₁Depth of groove, H₂-wafer thickness, α -angle of inclination of flow guiding surface; beta-setting a central angle corresponding to the circumferential dimension of the notch at the position of the flow guide surface.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Fig. 1a, 1b and 2 illustrate a wafer carrier tray currently used in the prior art, the wafer carrier tray including a tray body 10 and grooves 20 formed on the tray body, fig. 1a is a schematic top view of the wafer carrier tray 10, fig. 1b is a schematic top view of the wafer carrier tray 10 after a substrate 30 is placed in the groove 20, and fig. 2 is a schematic cross-sectional view of the structure of fig. 1b along a-a' of fig. 1a, wherein the flow direction of deposition source gases is shown by arrows of a curve 31 in fig. 1b and fig. 2. As shown in FIG. 2, in the conventional wafer carrier, the depth H of the groove₁Slightly larger than the thickness H of the wafer₂And the side walls at the groove opening of the groove are vertical to the surface of the wafer arranged in the groove. Because the height difference H (H ═ H) exists between the groove of the wafer bearing disc and the wafer₁-H ₂) In which H is₁Is the depth of the groove H₂Is the wafer thickness. Under high rotational speed, when depositing source gas curve 31 arrow direction by disk body surface gradual flow to wafer, the difference in height h has certain shielding effect to the wafer edge, and this moment, reactant gas is less with the wafer contact at the wafer edge, leads to reactant gas can't be effectively deposited at the wafer edge (for example 4 regions in the picture), causes the epitaxial layer at wafer edge and the epitaxial layer of wafer other positions to have the difference, and the epitaxial deposition quality of wafer edge is poor to the yield of product has been reduced.

Fig. 3a is a schematic top view of a wafer carrier according to the present invention, which provides a wafer carrier comprising:

the wafer-placing device comprises a tray body 10, a groove 20 arranged on the tray body 10 and used for placing a wafer, and a flow guide surface 21 arranged on the side wall of the tray body, wherein the flow guide surface is arranged at a reaction gas inlet and is inclined relative to the wafer.

Referring to fig. 4 to 6, the reactant gas flow 31 flows from the central portion of the disk 10 to the periphery, and the reactant gas flow is intensively flowed into the groove, and the position corresponding to the position where the reactant gas flow intensively flowed into the groove is defined as a reactant gas inlet position.

In this embodiment, an edge of one side of the diversion surface 21 away from the groove 20 may be a straight line, as shown in fig. 3 a; in other embodiments, the edge of the deflector surface 21 away from the recess 20 may also be curved, as shown in fig. 3 b. The specific line of the side edge of the diversion surface 21 far away from the groove 20 is not limited in this case.

In this embodiment, the recess 20 is used for placing the wafer 30, and after the wafer 30 is placed in the recess 20, as shown in fig. 3c, the tray 10 is placed in an epitaxial apparatus, and an epitaxial layer is formed on the surface of the wafer 30 by the flow of the deposition source gas in the epitaxial apparatus. In the epitaxial deposition process, the wafer is placed in the groove, so that the wafer can be prevented from freely sliding in the disc body.

In the present embodiment, there are 3 grooves 20, however, the number of the grooves 20 is not limited in the present invention, and may be more or less. It will be appreciated by those skilled in the art that depending on the size of the wafer carrier, the size of the grooves 20, the number and location of the grooves 20 can be flexibly set to meet the process requirements of wafers of different sizes (e.g., 8 inches and 6 inches in diameter).

It is understood that the present invention is not limited to any particular material for the wafer carrier, and may be, for example, a high melting point solid material such as graphite or molybdenum.

In this embodiment, to match the general shape of a wafer in the art, the recess 20 is preferably circular. However, the shape of the groove 20 is not particularly limited in the present invention, and may be set according to the shape of the wafer.

In this embodiment, in order to ensure that the wafer is effectively fixed in the groove, the angle β between the circumferential arc length of the guiding surface 21 and the center of the groove 20 is not too large, and the range of β is not greater than 180 °, and preferably not greater than 120 °. Specifically, as shown in fig. 3a to 3c, the diversion surface 21 is disposed along the circumferential direction of the groove 20 (see fig. 4 to 6), and along the circumferential direction of the groove 20, a central angle β corresponding to the circumferential arc length of the diversion surface 21 along the groove is not greater than 180 °, and preferably not greater than 120 °.

Fig. 4 to 6 are schematic structural views of a cross section along a-a' of the structure shown in fig. 3c, in which the arrow direction of the curve 31 in fig. 3c and 4 shows the flow direction of the deposition source gas. Wherein the deposition source gas may be a high purity metal organic source, abbreviated as M0 source.

In this embodiment, the position of the deposition source gas inlet refers to the position of the inlet where the flow of the deposition source gas flows from the disk body to the recess during the epitaxial deposition. In other embodiments, the position of the inlet may be adjusted according to the flow direction of the source gas, such as when the tray 10 is rotated, the direction of the flow may be changed. Specifically, in actual operation, when the wafer carrier is rotated counterclockwise or clockwise, the reaction gas is not directly blown to the grooves 20, and the reaction gas is also deflected, so that the guiding grooves 21 on the grooves 20 are also inclined to some extent. When the wafer carrier is rotated counterclockwise, the disposition of the guiding grooves 21 is as shown in fig. 8. When the wafer carrier is rotated clockwise, the position of the guiding grooves 21 is opposite to the inclined angle in fig. 8. The specific position of the diversion trench 21 is determined according to the rotation direction of the wafer carrier.

In this embodiment, a flow guiding surface 21 is disposed on a side wall of the disk at the reaction gas inlet, the flow guiding surface 21 is disposed to be inclined with respect to the wafer 30, and the flow guiding surface 21 extends in a direction of a bottom of the groove 20. Wherein, the direction of the diversion surface 21 to the bottom of the groove 20 means: on a line connecting any point of the flow guide surface 21 at the notch with any point on the bottom surface of the groove, the direction from the notch to the bottom surface is directed.

During epitaxy, the reaction gas flows through the guiding surface 21 and then contacts the edge of the wafer 30 disposed in the groove 20, and then flows to other portions of the wafer 30 from the edge of the wafer 30 corresponding to the guiding surface 21.

The quality of epitaxial deposition at the wafer edge can be reduced as long as the guiding surfaces 21 have an inclination angle with respect to the vertical plane, but in order to improve the quality of epitaxial deposition at the wafer edge, the inclination angle of the guiding surfaces 21 should be less than 90 °, and preferably the inclination angle of the guiding surfaces 21 is 10 ° to 60 °. Here, the inclination angle of the guiding surface refers to an angle α between the guiding surface 21 and the surface of the wafer 30, and in fig. 4, for convenience of marking, the angle α is shown as an angle between the guiding surface 21 and the surface of the tray 10, in which case the surface of the tray 10 is parallel to the surface of the wafer 30, as shown in fig. 4.

With reference to FIGS. 4-6, the height H of the diversion surface 21 is greater than or equal to H₁-H ₂And the height H of the flow guide surface is less than or equal to H₁；H ₁Is the depth of the groove H₂Is the wafer thickness. Wherein the depth H of the groove₁Is the distance from the surface of the tray 10 to the bottom surface of the recess. In the design structure, the bottom edge of the flow guide surface 21 is flush with the surface of the wafer 30 or lower than the surface of the wafer 30, so that the reaction gas can stably flow through the edge of the wafer, and the reaction gas can fully contact with the edge of the wafer, the epitaxial deposition quality of the edge of the wafer is improved, and the difference between the deposition quality of the edge of the wafer 30 and the deposition quality of the center of the wafer 30 is reduced. The height of the guide surface 21 is less than or equal to the depth of the groove, and when the height of the guide surface 21 is equal to the depth of the groove, the wafer bearing disc is higher in universality and can be suitable for wafers with different thicknesses.

Specifically, as shown in fig. 4 to 6, the bottom of the diversion surface 21 may be directly connected to the upper surface of the wafer 30; in other embodiments, the bottom of the deflector surface 21 may be connected to the sidewall of the wafer 30, as shown in fig. 5; it is understood that the bottom of the deflector surface 21 may be connected to the bottom surface of the wafer 30, as shown in fig. 6; the scheme is not limited to this, as long as the included angle between the diversion surface 21 and the horizontal plane is ensured, that is, the range of the inclination angle alpha of the diversion surface 21 is 10-60 degrees, and the height H of the diversion surface₁≥H≥H ₁-H ₂(H ₁Is the depth of the groove H₂Wafer thickness).

The structure of the flow guide surface 21 is not specifically limited in the present invention, as long as the flowing direction of the reaction gas flow can be changed, so that the reaction gas flow smoothly flows over the edge of the wafer and fully contacts with the edge of the wafer. The flow guiding surface 21 may be a plane or a curved surface (as shown in fig. 7), and the front projection view of the flow guiding surface 21 may be a trapezoid, etc., which is not limited in this case as long as the direction of the reactive gas flow is changed.

In this embodiment, the sidewall of the groove 20 is perpendicular to the bottom of the groove 20, so as to prevent the wafer 30 from slipping during the epitaxial deposition process.

In the wafer carrier tray of this embodiment, the guiding surface 21 is disposed at the notch of the groove to change the flow direction of the reaction gas, which can be specifically seen in the direction of the arrows in fig. 4-6, and the direction of the arrows in fig. 4-6 shows the flow direction of the reaction gas. The change of the gas flow direction of the reaction gas increases the contact probability of the reaction gas and the edge of the wafer 30, improves the surface epitaxial deposition quality of the edge of the wafer 30, and ensures that the surface epitaxial deposition quality of the edge of the wafer 30 is consistent with the epitaxial deposition quality of other positions of the wafer 30, thereby improving the yield of the epitaxial process of the wafer 30.

In the deposition process, the reaction gas is introduced from the top of the vapor deposition device and blown to the central part of the disk body 10, and then the reaction gas flows from the central part of the disk body 10 to the periphery. The reactive gas flows through the guiding surface 21 and then flows into the groove 20 and contacts with the edge of the wafer 30 placed in the groove 20.

According to the invention, the groove 20 is arranged on the disc body 10, the groove 20 is used for bearing the wafer 30, and the wafer 30 is placed in the groove 20 during epitaxial deposition, so that the wafer 30 is prevented from freely sliding in the disc body. During epitaxial deposition, the distribution of the reaction gas influences the quality and uniformity of epitaxial deposition, and the flow direction of the reaction gas flow can be changed by arranging the inclined flow guide surface, so that the reaction gas is uniformly distributed on the surface of the wafer 30, and the uniformity of the reaction gas deposition on the surface of the wafer 30 is ensured.

In the above embodiment, the wafer 30 is directly disposed in the groove 20, and in other embodiments, the bottom of the groove is further provided with a step 40, as shown in fig. 9, the wafer 30 is disposed on the step 40 at the bottom of the groove, so that direct contact heating to the substrate is changed into radiation heating, the temperature on the wafer is uniform, and the quality of the epitaxial layer formed on the wafer is improved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

A wafer carrier tray, comprising:

a tray body;

the groove is arranged on the tray body;

and the flow guide surface is arranged on the side wall of the disc body, is arranged at the position of the reaction gas inlet and is obliquely arranged relative to the wafer.
The wafer carrier tray of claim 1, wherein the height H of the baffle surface is greater than or equal to H₁-H ₂And the height H of the flow guide surface is less than or equal to H₁；

Wherein H₁Is the depth of the groove H₂Is the wafer thickness.
The wafer carrier of claim 1, wherein the sidewalls of the recess are perpendicular to the bottom surface of the recess.
The wafer carrier of claim 1, wherein the deflector surface has a central angle of no more than 180 ° along the circumferential arc of the groove.
The wafer carrier tray of claim 1, wherein the bottom of the recess is stepped.
Wafer epitaxy apparatus comprising a wafer carrier as claimed in any of claims 1 to 6.