TW202037753A - Substrate holder for use in a cvd reactor - Google Patents

Abstract

The invention relates to an apparatus for use in a CVD reactor (1), having a substrate holder (10) having at least three support protrusions (13) arising from a broadside face (12), which have support faces (14) lying in a common plane and having a circle-equivalent first diameter (D1) and which are arranged such that a central zone (Z) of a substrate (17), which is surrounded by an edge zone (R) supported on the support faces (14), has a distance (a) from the broadside face (12). According to the invention, the support protrusions (13) can be arranged directly on the edge of the broadside face (12) or in an edge strip having a radial extension of 600 [mu]m. The support protrusions (13) can furthermore be multilevel.

Description

Substrate rack used in CVD reactor

The present invention relates to a device for use in a CVD reactor. It has a substrate holder, which includes at least three bearing projections starting from a wide side surface, and the bearing projections have a first The carrying surface of the equivalent circle diameter is arranged so that the central area surrounded by the edge area of the substrate supported on the carrying surface has a distance from the wide side surface.

The aforementioned type of substrate holder is used in a CVD reactor for holding flat substrates, wherein the substrate holder is heated from the lower wide side. The upper wide side dissipates the heat to the substrate leaning on the substrate holder. Since the substrate cannot be flat against the wide side of the substrate holder due to thermal deformation or other strains, a bearing protrusion is generated on the wide side of the substrate holder, and the edge area of the substrate is supported on the bearing protrusion. In this way, the edge area of the substrate is supported by a number of convex points arranged on the arc line. The heat transfer from the wide side of the substrate holder to the substrate is carried out through heat radiation or heat conduction. The heat transfer depends on the thermal conductivity of the gas in the process chamber, which is located between the bottom side of the substrate and the wide side of the substrate holder. Compared with the area located between the protrusions, the area within the protrusions has a greater specific heat transport, so in the area of the protrusions, higher temperatures appear on the substrate surface. When the III-V group semiconductor layer is coated on the surface of the substrate, unevenness may appear in the convex part. US 2003/0209326 A1 describes a recess provided in the bottom edge region of the cavity of the substrate holder, in which a pin is inserted. The pin inserted into the recess constitutes a bearing protrusion, which has a bearing surface with a diameter of about 600 μm. Between the bottom side of the substrate and the wide side of the substrate holder The distance here is also about 600 μm.

US 6,840,767 B2 describes a substrate holder with a supporting surface for accommodating the substrate. The supporting surface is composed of a plurality of protrusions uniformly distributed within the range of the supporting surface, wherein each of the plurality of protrusions Both form a bearing surface with a circular equivalent diameter of about 250 μm.

US 2010/0227455 A1 describes a substrate holder including a cavity provided therein, and a substrate supported on the edge side is provided in the cavity.

In order to minimize the horizontal temperature gradient on the surface of the substrate to be coated, DE 10 2016 103 530 A1 has proposed: a concave part constructed as a groove starting from the wide side of the bearing protrusion. The dome-shaped end surface of the truncated cone shape starting from the concave portion should be in contact with the bottom side of the substrate, and the contact surface should have a maximum equivalent circle diameter of 300 μm.

The object of the present invention is to provide measures to further reduce the aforementioned temperature non-uniformity in the surface.

This objective is achieved through the inventions given in the scope of the patent application. Among them, the appendix is not only a beneficial improvement scheme of the invention given in the independent item, but also an original solution for the objective.

According to one aspect of the present invention as an improvement to the device described in DE 10 2016 103 530 A1, the bearing is composed of at least two stacked column sections, wherein the uppermost column section forms A flat bearing surface. The uppermost column section may have the smallest equivalent circle diameter of the bearing. The lowermost column section may have the largest equivalent circle diameter of the bearing. It is also preferable here that the bearing projection starts from a flat section of the wide side. However, the following solution can also be adopted: the lowermost column section is surrounded by an annular recess, in particular by a rounded bottom. When the total height exceeds 300 μm, the convex-bearing system is constructed as a two-step type. in In this case, the diameter of the second lower step portion may fall within a range between 1200 μm and 1500 μm. The diameter of the upper step portion may be 300 μm, and is particularly smaller than the material thickness of the substrate.

According to the second aspect of the present invention as an improvement to the device described in US 2003/0209326 A1, the distance between the bearing protrusions and the edge of the broad side surface is a maximum of 6000 μm, 3000 μm, 1000 μm, 600 μm or 300 μm. The diameter defined by the extension of the wide side surface is preferably slightly smaller than the diameter of the substrate carried by the projection, so that the substrate extends beyond the edge of the wide side surface through the edge area. A bearing ring can be provided under this protruding area, which can be clamped by the fingers of the grasping arm from below, so as to be removed from the substrate holder. With this carrier ring, the substrate can be manipulated. The bearing protrusions may be arranged in an edge strip of one of the wide sides, which has a strip width of 6000 μm, 3000 μm, 1000 μm, 600 μm, or 300 μm at most. However, preferably, the bearing protrusions are directly located at the edge, wherein the edge is particularly adjacent to the peripheral surface (which is a cylindrical surface). This peripheral surface can again adjoin a step, which is particularly suitable for supporting the carrier ring. In another aspect of the present invention with independent meaning, the height of the bearing protrusions is greater than the maximum diameter. In particular, the maximum circle equivalent diameter of the bearing protrusion is 300 μm, and its height is at least 400 μm. The projections should start directly from a flat section of the wide side. Here, the flat section of the broad side surface extends at least in an area separated from the supporting protrusion by 5000 μm.

A device particularly according to the third aspect of the invention (this aspect is also an improvement of the device according to DE 10 2016 103 530 A1) proposes that all contact surfaces are formed by a bearing surface extending in a common plane constitute. Embodiments of the present invention may have a flat bearing surface with a first equivalent circle diameter of at most 600 μm, preferably at most 300 μm. The minimum circle equivalent diameter of the bearing surface can be 150μm or 300μm. The height of the bearing protrusion can fall within a range between 150 and 400 μm. The following solution can be adopted: the wall portion of the truncated cone-shaped convex bearing starts from the annular recess in a manner without bending points.

The aforementioned aspect may have the following optional characteristics. The height that can be equal to the distance between the bearing surface and the reference plane defined by the broad side surface is greater than the equivalent circle diameter of the flat bearing surface. The circle equivalent diameter is equal to the diameter of a circle having the same area as the bearing surface. In an improved solution, the maximum diameter of the bearing protrusion may be less than 600 μm. The diameter here also refers to a circle equivalent diameter, which is equal to the diameter of a circle having the same cross-sectional area as the bearing projection. In addition, particularly according to an aspect of the present invention, the equivalent circle diameter of the bearing surface and/or the equivalent circle diameter of the largest cross section of the bearing protrusion is smaller than the thickness of the substrate, wherein the substrate is a flat body. The height of the protrusion may be at least 100 μm, at least 200, or at least 400 μm. In an improved solution of the present invention, the cross section of the bearing protrusion is not circular. The bearing projection may have a polygonal plan view. The plan view can be hexagonal or rectangular. In addition, the bearing protrusion can be formed by a columnar body, and the plan view of the columnar body can be circular or non-circular. However, the following scheme can also be adopted: the cross-section of the bearing protrusion decreases in the direction away from the wide side. Accordingly, the maximum cross-section of the bearing protrusion can be, for example, the base surface of the bearing protrusion, from which the bearing protrusion starts from the wide side surface. In this case, the smallest cross section of the bearing is the bearing surface. The cross section of the bearing protrusion can continuously decrease from the wide side to the bearing surface. However, the cross section can also be reduced in steps. Accordingly, the bearing protrusion may have, for example, two step sections, which respectively have columnar shapes with different cross sections. The flat bearing surfaces are located in a common plane corresponding to the bottom side of the substrate. According to a preferred solution of the present invention, the bearing protrusions directly start from the wide side surface. In this case, the reference plane extends through the root of the bearing. However, in one aspect of the present invention, the bearing protrusion can also be surrounded by a ring-shaped recess, as disclosed in DE 10 2016 103 530 A1 or US 2003/0209326 A1. In this case, the reference plane extends through the radially outer edge of the recess, which may be a groove. However, the reference plane can also extend through the lowest point of the recess. In an improved solution of the present invention, the convex-bearing system material uniformly corresponds to the substrate holder. The substrate holder can be composed of silicon carbide or coated graphite. In order to manufacture the substrate holder of the present invention, a blank made of graphite or silicon carbide is used, in particular, the blank is subjected to abrasive processing by a milling cutter. With the milling cutter, for example, one by one Step by step deepen the wide side, where the bearing convexity remains unchanged. With this method, a step can also be produced, and a support ring can be attached to the step, and the support ring is used to remove the substrate carried by the projection. In addition, the device may also have a substrate holder, and the substrate holder has a cavity for mounting the substrate. In one solution, the substrate holder itself can realize the function of the substrate holder and has a plurality of substrate holders, and the substrate holders respectively have bearing protrusions arranged on a circular arc around the center. Preferably, six bearing projections are provided respectively.

1: CVD reactor

2: Gas inlet component

3: substrate holder

4: Process room

5: The top of the process room

6: cavity

7: Gas transmission pipeline

8: bottom of cavity

9: heating device

10: substrate rack

11: Lower wide side

12: Upper wide side

13: bearing convex

13': side

14: bearing surface

14': plane

15: Upper section

16: lower section

17: substrate

17': bottom side of substrate

18: Datum plane

19: Carrying ring

20: grooves, recesses

20': Edge

20": Vertex line

21: Stage

22: bearing shoulder

23: prominent area

24: circumference

25: Edge

A1: Section

B: thickness

D1: diameter

D2: diameter

D3: diameter

R: marginal area

Z: central area

a: distance

h: height

The embodiments of the present invention will be described below with reference to the drawings. among them:

Figure 1 is a schematic cross-sectional view of a CVD reactor 1,

Figure 2 is an enlarged view of part Ⅱ in Figure 1,

Figure 3 is an enlarged view of part Ⅲ in Figure 2,

Figure 4 is a view of the second embodiment of the present invention as shown in Figure 3,

Figure 5 is a cross-sectional view according to the line V-V in Figure 3,

Figure 6 is a view of the third embodiment of the present invention as shown in Figure 3, and

FIG. 7 is a top view of the substrate holder 10 to clarify the position of the bearing protrusion 13.

Fig. 1 is a schematic cross-sectional view of a CVD reactor 1 including a reactor shell, and a process chamber 4 is located in the reactor shell. The gas inlet member 2 extends into the process chamber 4, through which process gases such as organometallic compounds of main group III elements and hydrides of main group V elements can be fed into the process chamber 4 together with carrier gas. In the upward direction, the process chamber 4 is defined by the top 5 of the cooling process chamber as appropriate. In the downward direction, the process chamber 4 is defined through the substrate holder 3 made of graphite or similar suitable material. A heating device 9 is provided under the substrate holder 3, and heat is transferred to the substrate holder 3 by the heating device.

On the top side of the substrate holder 3 facing the process chamber 4, a surrounding substrate holder Several cavities 6 are provided in the circular layout at the center of 3, and a substrate holder 10 is provided in each of the cavities. A carrier gas can be fed into the cavity 6 through the gas delivery pipeline 7, and the substrate holder 10 abuts on the carrier gas. The air cushion that carries the substrate holder 10 is generated, so that the substrate holder 10 rotates around the axis of the substrate holder in a manner of being inserted into the cavity 6. The bottom side 11 of the substrate holder 10 may be flat. However, the bottom side can also have several spatial structures. In this regard, the schema is not drawn to scale.

The substrate holder 10 has a radially outer step 21 on which a carrier ring 19 is attached. The carrier ring has a radially inward carrier step 22, and the carrier ring extends out of the substrate carrier through a protruding area 23 The radial outer area of 10. The top side of the carrier ring 19 is substantially flush with the top side of the substrate holder 3.

As shown in FIGS. 2, 3, 4, and 6, the substrate holder 10 has an upper wide side surface 12 opposite to the lower wide side surface 11, which extends substantially in a plane. The bearing protrusion 13 starts from the edge section of the upper wide side surface 12. As shown in FIG. 7, there are a total of six bearing protrusions 13 arranged around the center of the substrate holder 10 with a uniform angular distribution. The bearing protrusions 13 each have a bearing surface 14, wherein the bearing surfaces 14 of all the bearing protrusions 13 extend in a common plane. This plane is formed by the bottom side 17 ′ of the substrate 17, which is carried by the substrate holder 10. The disc-shaped substrate 17 has a central area Z which is located hollow above the wide side surface 12 by a distance a. The substrate 17 is carried by the bearing protrusion 13 only in the edge region R, wherein the outermost edge of the substrate 17 is located above the bearing shoulder 22, so the substrate 17 can be removed from the substrate holder 10 by lifting the bearing ring 19.

In the embodiment shown in FIGS. 3 and 4 of the bearing protrusion 13, it involves a substrate holder 10 made of silicon carbide. The substrate holder 10 is processed from a solid material through an abrasive process, for example, a milling cutter. Correspondingly, the bearing protrusion 13 is connected to the block material of the substrate holder 10 in a material consistent manner. The bearing protrusion 13 has a hexagonal plan view. The largest cross-section of the bearing projection 13 is located in the root region of the bearing projection 13, in which the bearing projection 13 starts in a plane The wide side surface 12 extending to the edge of the bearing protrusion 13.

In the embodiment shown in FIG. 4, the bearing surface 14 has a cross section that is substantially the same as the cross section of the root region of the bearing protrusion 13. D1 represents the equivalent circle diameter of the bearing surface 14 extending in a plane. D2 represents the circle-equivalent diameter of the root surface of the bearing projection 13 extending in the wide side surface 12. In this embodiment, the circle equivalent diameter D1 is as large as D2 and is about 300 μm. However, the diameter can also reach 600 μm. The height h of the bearing protrusion 13 here is about 400 μm. The height h can also be smaller, but especially greater than 100 μm. A total of six bearing projections 13 start from a flat section of the broad side 12. The broad side plane extends at least in the area surrounding the bearing with a radius of 5 mm. Preferably, the entire wide side surface 12 does not have steps or other protrusions or recesses. The wide side surface 12 extends at least approximately flatly, so that at each position, the maximum distance between it and a reference plane extending in a plane with mathematical accuracy is 10 μm.

FIG. 3 shows an embodiment of the bearing projection 13 which is composed of two superimposed column sections 15, 16. The lower section 16 has the largest cross section with an equivalent circle diameter D2 of about 600 μm. The upper section 15 has an equivalent circle diameter D1 of approximately 300 μm. The height h here is also about 400 μm. The two-stacked cylindrical sections 15, 16 may have a non-circular, in particular polygonal, hexagonal or rectangular cross-section. The step surface between the upper section 15 and the lower section 16 preferably extends parallel to the wide side surface 12 or the bearing surface 14. In this embodiment, the design of the wide side surface 12 is the same as that shown in FIG. 3.

FIG. 6 shows a third embodiment of the bearing projection 13. The substrate holder 10 can be made of graphite and coated with silicon carbide after molding. The bearing protrusion 13 here has a side surface which extends along the enveloping surface in the shape of a truncated cone. The envelope surface may be a rotating surface. The envelope surface is especially a conical surface that has been reversed. In the embodiment shown in FIGS. 3 and 5, the bearing projection 13 starts directly from a plane. In contrast, in the embodiment shown in FIG. 6, the bearing projection 13 starts along the bearing projection 13 The edge of the recess 20 extends.

In the embodiment shown in FIGS. 4 and 6, the bearing projection 13 is directly located at the edge 24 of the wide side surface 12, where the wide side surface 12 is adjacent to a peripheral surface 24 formed by a cylindrical wall. The peripheral surface 24 transitions into the step 21, on which the bearing protrusion 13 is located. The side of the bearing protrusion 13 away from the center of the substrate holder 10 in the radial direction is formed by a section of a cylindrical surface. The radially outward wall of the bearing protrusion 13 is spaced from the edge of the substrate 17 carried by the bearing protrusion 13 by a section A1, wherein the distance can be 3 to 3.5 mm.

The concave portion 20 shown in FIG. 6 may extend along an arc, and the center of the arc is the center of the bearing protrusion 13. The outer diameter D3 of the circular contour line of the recess 20 may fall within a range between 1500 μm and 2000 μm. The depth of the groove 20 may be 50 μm. The apex line 20' of the groove 20 can define a reference plane 18 from which the height h is measured, which is about 150 μm here. The equivalent circle diameter D1 of the bearing surface 14 can also be less than 300 μm here. In this embodiment, the equivalent circle diameter is about 150 μm.

The distance a between the bottom side 17 ′ of the substrate and the wide side surface 12 may fall within the range of 100 μm. The wide side surface 12 can extend flatly except for the annular recess 20, where the plane also refers to the following: it extends slightly in a concave shape and deviates from the reference plane with mathematical accuracy at each position by up to 10μm, up to 20μm or up to 50μm .

In the embodiment shown in FIG. 3, the second step may have the same step height. The equivalent circle diameter D1 of the bearing surface 14 may be less than 400 μm, preferably less than 300 μm. However, the circle-equivalent diameter may also be greater than 300 μm, and have a maximum value of, for example, 600 μm. The diameter D2 of the lowermost step of the two-step bearing protrusion 13 may be 1000 μm, 1200 μm or even 1500 μm. The equivalent circle diameter D2 of the lowermost step is particularly smaller than 1500 μm, smaller than 1200 μm, or smaller than 1000 μm.

The main feature of the present invention is as follows: the bearing protrusion 13 constitutes a spacer element having a height and a diameter, wherein the diameter is less than 750 μm and preferably about 300 μm. Bearing convex 13 is particularly a component of the same material of the substrate holder 10. These projections are especially not inserts, but are manufactured through abrasive processes. The number of supporting elements is preferably less than 10. The number of load-bearing elements is particularly greater than or equal to 3, 4, 5 or 6, wherein the load-bearing elements are distributed evenly around a center in the radial direction. In addition, the circle equivalent diameter of the bearing protrusion 13 may be smaller than its height h. In addition, the following solution can be adopted: the substrate holder 10 is a component of the substrate holder configuration, wherein the substrate holder 3 has several cavities, which are evenly distributed around the center of the substrate holder 3, and a substrate holder is provided in each cavity. The substrate holder is preferably made of silicon graphite. But the substrate holder can also be made of graphite and then coated with silicon carbide. In a particularly preferred technical solution, the carrying element has a second-order shape, a truncated cone or a cylindrical shape.

The foregoing embodiments are used to illustrate the inventions contained in the application as a whole. These inventions are at least independently constituted by the following feature combinations to form improvements over the prior art, wherein two, several or all of these feature combinations Can also be combined with each other, namely:

A device, characterized in that: the bearing projection 13 is composed of at least two stacked column sections 15, 16, wherein the uppermost column section 15 has a flat bearing surface with a first circle equivalent diameter D1 forming a contact surface 14, and the lowermost column section 16 has a second equivalent circle diameter D2.

A device characterized in that the second circle equivalent diameter D2 of the largest cross section of the bearing protrusion 13 is less than 600 μm.

A device is characterized in that the distance between the supporting protrusion 13 and the edge 25 of the wide side surface 12 is at most 6000 μm, 3000 μm, 1000 μm, 600 μm or 300 μm.

A device is characterized in that the bearing projection 13 is directly arranged at the edge 25, or arranged in an edge strip with a maximum radial extension of 6000 μm, 3000 μm, 1000 μm, 600 μm or 300 μm.

A device, characterized in that: the edge 25 is adjacent to the peripheral surface 24, the The peripheral surface is adjacent to the first step.

A device is characterized in that the side surface 13' of the bearing protrusion 13 extends at least partially along the truncated cone-shaped envelope surface.

A device, characterized in that: the height h equivalent to the distance between the bearing surface 14 and the reference plane 18 defined by the wide side surface 12 is at least 400 μm, and/or the bearing surface 14 has a first circle with a maximum of 600 μm, in particular a maximum of 300 μm The equivalent diameter D1, and/or, the bearing projection 13 directly starts from a flat area or a recess of the wide side surface 12.

A device is characterized in that the cross section of the bearing protrusion 13 is not circular, and particularly has a polygonal, hexagonal or rectangular plan view.

A device is characterized in that the material of the bearing and convex 13 series corresponds to the substrate holder 10, wherein the substrate holder 10 is made of graphite or silicon carbide.

A method, characterized in that the bearing protrusion 13 is processed from a solid material of a blank made of graphite or silicon carbide through an abrasive process.

A device characterized in that the maximum circle equivalent diameter of the bearing protrusion 13 is greater than its height h.

An application is characterized in that the thickness of the substrate carried by the bearing protrusion 13 is smaller than the first equivalent circle diameter D1 of the carrying surface 14.

All disclosed features (as single features or feature combinations) are the essence of the invention. Therefore, the disclosed content of this application also includes all the content disclosed in the related/attached priority files (copy of the earlier application), and the features described in these files are also included in the scope of patent application of this application. The ancillary items describe the characteristics of the improvement scheme of the present invention with respect to the prior art with its characteristics (even if the characteristics of the related claims are not included), and its purpose is to make a divisional application on the basis of these claims. The invention given in each claim may further have one of the features given in the foregoing description, especially marked with symbols and/or given in the symbol description Or several items. The present invention also relates to the following design forms: the individual features mentioned in the foregoing description are not realized, especially features that are not necessary for specific applications or can be replaced by other technically equivalent components.

6: cavity

10: substrate rack

12: Upper wide side

13: bearing convex

14: bearing surface

17: substrate

17': bottom side of substrate

B: thickness

D1: diameter

D2: diameter

a: distance

h: height

Claims (12)

A device for use in a CVD reactor (1), having a substrate holder (10), which includes at least three bearing protrusions (13) starting from a wide side surface (12), and a flat substrate (17) The edge area (R) can be supported on the bearing protrusions under the condition of forming a contact surface so that the central area (Z) surrounded by the edge area (R) of the substrate (17) has the same distance as the wide side (12) Distance (a), where the height (h) of the bearing projections (13) is greater than the first circle equivalent diameter (D1) of the contact surfaces, and the diameter is at most 300μm and larger than the maximum cross section of the bearing projections (13) The second equivalent circle diameter (D2) is characterized in that the bearing projection (13) is composed of at least two stacked column sections (15, 16), wherein the uppermost column section (15) has a The flat bearing surface (14) with the first equivalent circle diameter (D1) and the lowermost column section (16) of the contact surface have the second circle equivalent diameter (D2). The device of claim 1, wherein the second circle equivalent diameter (D2) of the largest cross-section of the bearing protrusion (13) is less than 600 μm. A device for use in a CVD reactor (1) has a substrate holder (10), which includes at least three bearing projections (13) starting from the wide side (12), and the bearing projections have a common The bearing surface (14) with the first circle equivalent diameter (D1) in the plane is arranged such that the central area (R) surrounded by the edge region (R) of the substrate (17) supported on the bearing surface (14) Z) has a distance (a) from the wide side surface (12), characterized in that: the distance between the bearing protrusions (13) and the edge (25) of the wide side surface (12) is a maximum of 6000μm, 3000μm, 1000μm, 600μm or 300μm. Such as the device of claim 3, wherein the bearing protrusions (13) are directly arranged at the edge (25), or arranged on an edge strip with a maximum radial extension of 6000μm, 3000μm, 1000μm, 600μm or 300μm Inside. Such as the device of claim 3, wherein the edge (25) and the peripheral surface (24) Adjacent, the peripheral surface is adjacent to the first step. The device of claim 1, wherein the side surface (13') of the bearing protrusion (13) at least partially extends along the truncated cone-shaped envelope surface. The device of claim 1, wherein the height (h) equivalent to the distance between the bearing surface (14) and the reference plane (18) defined by the broad side surface (12) is at least 400 μm, and/or the bearing surface ( 14) Having a first equivalent circle diameter (D1) of up to 600 μm, or up to 300 μm, and/or, the bearing protrusion (13) directly starts from a flat area or a recessed portion of the broad side surface (12). Such as the device of claim 1, wherein the cross section of the bearing protrusions (13) is not circular, and/or has a polygonal, hexagonal, or rectangular plan view. Such as the device of claim 2, wherein the material of the bearing protrusions (13) corresponds to the substrate frame (10) uniformly, wherein the substrate frame (10) is made of graphite or silicon carbide. A method for manufacturing the device of claim 1, which is characterized in that the bearing protrusions (13) are processed from a solid material of a blank made of graphite or silicon carbide through an abrasive process. The device as described in the preamble of claim 1 or any one of the foregoing claims, wherein the largest circle equivalent diameter of the bearing protrusions (13) is greater than the height (h). An application of the device of claim 1 in a CVD reactor, characterized in that the thickness of the substrate carried by the bearing protrusions (13) is smaller than the first circle equivalent diameter (D1) of the carrying surfaces (14).

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