TWM538237U - Wafer carrier with a 31-pocket configuration - Google Patents

Abstract

A wafer carrier configured to be used with a chemical vapor deposition device, the wafer carrier comprising: a body having a top surface and a bottom surface arranged opposite one another; a plurality of pockets defined in the top surface of the wafer carrier; a locking feature arranged on the bottom surface, said locking feature imparting angular momentum to the wafer carrier from an adjacent component; the improvement comprising the plurality of pockets consisting of a total of thirty-one pockets, each of the pockets arranged along one of three circles, wherein each of the circles is concentric with one another and with a circular outline formed by a perimeter of the top surface.

Description

Wafer carrier with arranged configuration of 31 accommodating areas

The present disclosure relates generally to semiconductor fabrication techniques, and more particularly to chemical vapor deposition (CVD) processes and related equipment for holding semiconductor wafers during processing.

In the fabrication of light-emitting diodes (LEDs) and other high-performance devices such as laser diodes, photodetectors, and field effect transistors, chemical vapor deposition (CVD) processes are typically used on top of sapphire or germanium substrates. The thin film stack structure is grown using a material such as gallium nitride. The CVD tool includes a processing chamber that is a sealed environment to allow the injected gas to react on the substrate (typically in the form of a wafer) to grow a thin film layer. An example of a current production line for such manufacturing equipment is the EPIK series of TurboDisc® and MOCVD systems manufactured by Veeco Instruments Inc. of Plainview, New York.

Some process parameters such as temperature, pressure, and gas flow rate are controlled to achieve the desired crystal growth. Different materials and process parameters are used to grow different layers. For example, a device formed of a compound semiconductor such as a group III-V semiconductor is typically formed by growing a continuous semiconductor compound layer using metal organic chemical vapor deposition (MOCVD). In this process, the wafer is exposed to a combination of gases, typically including a metal organic compound as a source of a Group III metal, and also including a wafer surface while the wafer is maintained at an elevated temperature. The source of the flowing V group elements. Typically, the organometallic compound and the Group V source are combined with a carrier gas that is not significantly involved in the reaction, such as nitrogen. An example of a III-V semiconductor is gallium nitride, which can be formed by the reaction of an organogallium compound and ammonia on a substrate having a suitable lattice gap (e.g., a sapphire wafer). The wafer is typically maintained at a temperature of between about 1000 and 1100 ° C during the deposition of gallium nitride and related compounds.

In an MOCVD process in which crystal growth occurs by chemical reaction on the surface of the substrate, process parameters must be carefully controlled to ensure that the chemical reaction is carried out under the desired conditions. Even small changes in process conditions can adversely affect device quality and production yield. For example, if a gallium and indium nitride layer is deposited, changes in the surface temperature of the wafer will cause variations in the composition and band gap of the deposited layer. Because indium has a relatively high vapor pressure, the deposited layer will have a lower indium ratio and a larger band gap in the region of the wafer where the surface temperature is higher. If the deposited layer is an active, LED structured light-emitting layer, the wavelength of the radiation formed by the wafer will also become unacceptable.

In the MOCVD processing chamber, the semiconductor wafer on which the thin film layer is grown is placed on a rapidly rotating rotating carousel called a wafer carrier to uniformly expose their surfaces within the reaction chamber. In a gaseous environment, a semiconductor material is deposited. The speed is approximately 1000 RPM. The wafer carrier is typically machined from a highly thermally conductive material such as graphite and is often coated with a protective layer such as a tantalum carbide material. Each wafer carrier has a set of circular indentations, or pockets, with a single wafer placed in its top surface. Typically, the wafer is supported in spaced relationship with the bottom surface of each of the accommodating regions to allow gas to flow around the edges of the wafer. US Patent Application Publication No. 2012/0040097, US Patent No. 8092599, US Patent No. 8021487, US Patent Application Publication No. 2007/0186853, US Patent No. 6,902,623, US Patent No. 6,506,252, and US Patent No. 6,492,625 Some examples of related techniques are described herein, the disclosure of which is incorporated herein by reference.

The wafer carrier is supported on a spindle in the reaction chamber such that the top surface of the wafer carrier having the exposed surface of the wafer faces upwardly toward the gas distribution device. As the shaft rotates, the gas is directed down onto the top surface of the wafer carrier and through the top surface to the periphery of the wafer carrier. The used gas is discharged from the reaction chamber through a port disposed under the wafer carrier. The wafer carrier is maintained at a desired elevated temperature by a heating element, typically a resistive heating element disposed beneath the bottom surface of the wafer carrier. These heating elements are maintained at a temperature higher than the desired temperature of the wafer surface, however the gas distribution device is typically maintained at a temperature well below the desired reaction temperature to prevent premature gas reaction. Thus, heat is transferred from the heating element to the bottom surface of the wafer carrier and flows upward through the wafer carrier to a single wafer.

The airflow over the wafer varies depending on the radial position of each wafer, with the wafers on the outermost side having a higher flow rate due to their faster speed during rotation. There may be temperature non-uniformities, ie cold spots and hot spots, even on each individual wafer. One variable factor that affects the formation of temperature non-uniformities is the shape of the containment area within the wafer carrier. Typically, the shape of the receiving area forms a circle in the surface of the wafer carrier. As the wafer carrier rotates, the wafer is subjected to substantial centripetal force at its outermost edge (ie, the edge furthest from the axis of rotation), causing the wafer to be squeezed against the inner wall of each of the accommodating regions of the wafer carrier . In this case, there is close contact between these outer edges of the wafer and the edges of the accommodating area. The increased heat transfer to these outermost portions of the wafer results in greater temperature non-uniformities, further exacerbating the above problems. The existing treatment method is to minimize temperature non-uniformity by increasing the gap between the edge of the wafer and the inner wall of the accommodating area, including designing the wafer as a part of the edge is flat (ie, flat-sided crystal circle). This flat portion of the wafer creates a gap and reduces the point of contact with the inner wall of the accommodating area, thereby alleviating temperature non-uniformity. Other factors that affect the thermal uniformity across the wafer supported by the wafer carrier include the heat transfer and emission characteristics of the wafer carrier, combined with the layout of the wafer containment area.

Another desirable feature for wafer carriers associated with temperature uniformity requirements is the increased throughput of the CVD process. The role of the wafer carrier in increasing process throughput is to maintain a large number of individual wafers. Providing a wafer carrier layout with more wafers affects the thermal model. For example, due to radiant heat loss from the edge of the wafer carrier, portions of the wafer carrier near the edge tend to be at a lower temperature than other portions.

Therefore, there is a need for a practical solution for wafer carriers in which temperature uniformity and mechanical stress in a high density layout are addressed.

The wafer carrier includes a new housing configuration. The configuration described herein facilitates heat transfer, as well as high packing density for the containment area for wafer growth.

A wafer carrier comprising: a body having top and bottom surfaces disposed opposite each other; a plurality of accommodating regions defined in the top surface of the wafer carrier a locking feature disposed on the bottom surface and for applying angular momentum from the adjacent component to the wafer carrier; the wafer carrier comprising a plurality of receiving regions including 31 accommodating regions Each of the accommodating regions is arranged along one of three circles, wherein each of the circles is concentric with each other and concentric with a circular contour formed by the top surface.

In one embodiment, four of the plurality of accommodating regions are arranged around a first one of the three circles; ten of the plurality of accommodating regions surround the three circles a second circular arrangement; and seventeen of the plurality of accommodating regions are arranged around a third of the three circles.

In an embodiment, the first circle is surrounded by the second circle and the second circle is surrounded by the third circle.

In an embodiment, the top surface comprises a diameter of approximately 675 mm.

In an embodiment, each of the plurality of accommodating regions includes a accommodating region diameter of about 50 mm.

In an embodiment, each of the plurality of accommodating regions includes a radial wall having a depth of about 430 μm.

In an embodiment, the locking feature is disposed at a geometric center of the bottom surface.

In an embodiment, the locking feature is selected from the group consisting of a spline, a chuck, or a keyed fitting.

In an embodiment, the top surface and the bottom surface each comprise a diameter, and the diameter of the top surface is greater than the diameter of the bottom surface.

In one embodiment, the wafer carrier is constructed for use in a metal organic chemical vapor deposition system.

Figure 1 shows a chemical vapor deposition apparatus in accordance with one embodiment of the present creation. The reaction chamber 10 defines a process environment space. A gas distribution device 12 is disposed at one end of the pod. This end with gas distribution device 12 is referred to herein as the "top" end of reaction chamber 10. This end of the pod is typically (but not necessarily) disposed at the top of the pod under a normal gravity frame. Thus, the downward direction as used herein refers to the direction away from the gas distribution device 12; and the upward direction refers to the direction of the cabin toward the gas distribution device 12, and whether these directions are consistent with the upward and downward directions of gravity Nothing. Similarly, the "top" and "bottom" surfaces of the elements are described herein with reference to the reference frame of reaction chamber 10 and gas distribution device 12.

The gas distribution device 12 is connected to sources 14, 16 and 18 for supplying process gases such as a carrier gas and a reactive gas used in a wafer processing process, such as a source of a metal organic compound and a group V metal. The gas distribution device 12 is arranged to receive various gases and direct the flow of the process gas to a generally downward direction. Ideally, the gas distribution device 12 is also coupled to a cooling system 20 that is arranged to circulate liquid through the gas distribution device 12 to maintain the temperature of the gas distribution device at a desired temperature during operation. A similar cooling configuration (not shown) may be provided to cool the walls of the reaction chamber 10. The reaction chamber 10 is also equipped with an exhaust system 22 that is arranged to remove exhaust gases from the interior of the cabin 10 through ports (not shown) located at or near the bottom of the tank, such that the gas distribution device is allowed 12 There is continuous airflow in the downward direction.

The rotating shaft 24 is disposed in the cabin such that the central shaft 26 of the rotating shaft 24 extends in the upward and downward directions. The shaft 24 is mounted to the nacelle by a conventional rotary pass-through device 28 including bearings and seals (not shown) such that the shaft 24 can be rotated about the central shaft 26 while maintaining the shaft 24 and reacting The seal between the walls of the cabin 10. The shaft 24 has a joint 30 at its top end, i.e. at the end of the shaft 24 closest to the gas distribution device 12. As discussed further below, the joint 30 is one example of a wafer carrier retention mechanism adapted to releasably engage a wafer carrier. In the particular embodiment described, the joint 30 is generally a frustoconical member that tapers toward the top end of the shaft and terminates in a flat top surface. The frustoconical element is an element having a conical frustum shape. The rotary shaft 24 is coupled to, for example, an electric motor driven rotary drive mechanism 32 that is arranged to rotate the rotary shaft 24 about the central shaft 26.

The heating element 34 is mounted within the cabin and surrounds the shaft 24 below the joint 30. The reaction chamber 10 is also provided with an inlet 36 leading to the forward body 38 and a door 40 for closing and opening the inlet. The door 40 is only exemplarily depicted in FIG. 1 and is shown movable between a closed position and an open position, wherein the closed position is shown in solid lines in which the door will react to the interior of the cabin 10 Isolated from the front compartment 38, the open position is shown at 40' in dashed lines. The door 40 is equipped with suitable control and actuation mechanisms for moving the door between an open position and a closed position. In practice, the door can include a shutter that is movable in an upward and downward direction, such as disclosed in U.S. Patent No. 7,276,124, the disclosure of which is incorporated herein by reference. The apparatus depicted in FIG. 1 may also include a loading mechanism (not shown) that is capable of moving the wafer carrier from the front pod 38 into the pod 10 and operating the wafer carrier and shaft 24 under operating conditions. Engaged, and also enables the wafer carrier to move out of the spindle 24 and into the front pod 38.

The device also includes a plurality of wafer carriers. Under the operating conditions illustrated in FIG. 1, the first wafer carrier 42 is disposed within the reaction chamber 10 and in an operational position, while the second wafer carrier 44 is disposed within the front chamber 38. Each wafer carrier includes a body 46 that is substantially in the shape of a disk having a central axis (see Figure 2). The body 46 is formed in an axisymmetric manner. In the operating position, the axis of the wafer carrier body coincides with the central axis 26 of the rotating shaft 24. The body 46 can be formed as a single piece or a combination of multiple pieces. The wafer carrier body can include a hub that defines a body about the central axis, as disclosed in US Patent Application Publication No. 20090155028, the disclosure of which is incorporated herein by reference. a small area; and a larger portion that defines the remainder of the disc-shaped body. Body 46 is desirably formed of a material that does not contaminate the process and that can withstand the temperatures encountered in the process. For example, a larger portion of the disc may be formed such that it is formed mostly or entirely of a material such as graphite, tantalum carbide or other refractory material. The body 46 generally has a flat top surface 48 and a bottom surface 52 that extend generally parallel to one another and generally perpendicular to the central axis of the disc. The body 46 also has one or more wafer retention features adapted to hold a plurality of wafers.

In operation, wafers 54 of disc-shaped wafers, such as sapphire, tantalum carbide or other crystalline substrates, are disposed within each receiving region 56 of each wafer carrier. Typically, wafer 54 has a thickness that is less than the size of its major surface. For example, a circular wafer approximately 2 inches (50 mm) in diameter may be approximately 430 [mu]m thick or less. As shown in FIG. 1, wafer 54 is provided with an upwardly facing top surface such that the top surface is exposed at the top of the wafer carrier. It should be noted that in various embodiments, the wafer carrier carries a different number of wafers. For example, in one embodiment, the wafer carrier can be adapted to hold six wafers. In another embodiment, the wafer carrier holds 25 wafers.

In a typical MOCVD process, wafer loaded wafer carrier 42 is loaded from front pod 38 into reaction pod 10 and placed in the operational position shown in FIG. In this case, the top surface of the wafer faces upward, toward the gas distribution device 12. The heating element 34 is actuated and the rotary drive mechanism 32 operates to rotate the spindle 24 and thereby rotate the wafer carrier 42 about the central axis 26. Typically, the shaft 24 is rotated at a rotational speed of approximately 50-1500 revolutions per minute. The process gas supply units 14, 16 and 18 are actuated to supply gas through the gas distribution device 12. The gas is transported downwardly toward the wafer carrier 42, past the wafer carrier 42 and the top surface 48 of the wafer 54, and is transported down to the periphery of the wafer carrier to the outlet and to the exhaust system 22. Thus, the top surface of the wafer carrier and the top surface of the wafer 54 are exposed to a process gas that includes a mixture of various gases supplied by various process gas supply units. Most typically, the process gas at the top surface is primarily comprised of a carrier gas supplied by the carrier gas supply unit 16. In a typical chemical vapor deposition process, the carrier gas can be nitrogen, and thus the process gas at the top surface of the wafer carrier is primarily composed of nitrogen having a certain amount of reactive gas composition.

The heating element 34 transfers heat to the bottom surface 52 of the wafer carrier 42 primarily by radiant heat transfer. Heat applied to the bottom surface 52 of the wafer carrier 42 passes upwardly through the body 46 of the wafer carrier to the top surface 48 of the wafer carrier. Heat transferred upward through the body is also transferred upward through the gap to the bottom surface of each wafer and through the wafer up to the top surface of wafer 54. Heat is radiated from the top surface 48 of the wafer carrier 42 and from the top surface of the wafer to the cooler components of the processing chamber (e.g., to the walls of the processing chamber and to the gas distribution device 12). Heat is transferred from the top surface 48 of the wafer carrier 42 and the top surface of the wafer to the process gas flowing through such surfaces.

In the depicted embodiment, the system includes a plurality of features designed to determine thermal uniformity of the surface of each wafer 54. In the present embodiment, temperature analysis system 58 receives temperature information, which may include temperature and temperature monitoring position information from temperature monitor 60. Additionally, temperature analysis system 58 receives wafer carrier position information, which in one embodiment may be from rotary drive mechanism 32. With this information, the temperature analysis system 58 constructs a temperature profile of the accommodating area 56 on the wafer carrier 42. The temperature profile represents the heat distribution on each of the accommodating regions 56 or the surface of the wafer 54 contained therein.

2 is a perspective view of wafer carrier 142, in accordance with an embodiment. 3 is a top plan view of the same wafer carrier 142. Wafer carrier 142 includes a body 146 having a top surface 148, and thirty one receiving regions 162 defined therein. In the embodiment illustrated in Figures 2 and 3, the receiving area 162 is disposed in three circles, each circle being concentric with a circle defined by the outer edge of the body 146. In the radially innermost circle, the four accommodating regions 162 are evenly spaced apart in azimuth. Similarly, in the radial intermediate circle, the ten accommodating regions 162 are evenly spaced apart in azimuth. In the radially outermost circle, the seventeen accommodating regions 162 are evenly spaced apart in azimuth. Each of the accommodating regions 162 is an aperture formed in the body 146 that extends substantially perpendicular to a plane in which the top surface 148 is disposed.

The arrangement of the accommodating regions depicted in Figures 2 and 3 is advantageous in that it provides a desired level of thermal uniformity while maintaining a relatively high density of accommodating regions 162 on the top surface 148. In an embodiment, the top surface 148 can have a diameter of approximately 675 mm. The accommodating area 162 is sized to be accommodated in this area. For example, in an embodiment, the receiving area 162 can have a diameter of approximately 50 mm.

Figure 3 also depicts a representative circle in which the accommodating area 162 is disposed. In the embodiment shown in FIG. 3, there are three circles: R1, R2 and R3, each having a different radius and arranged to be concentric with one another and concentric with the circular contour of the top surface 148.

4 is a side elevational view of the wafer carrier 142 of FIGS. 2 and 3. In the diagram shown in Figure 4, the relative difference in size between the top surface 148 and the bottom surface 152 can be seen. In particular, the top surface also extends toward the top and bottom of the page as shown in Figure 4, or further radially in the Figures shown in Figures 2 and 3. Each of the accommodating regions 162 previously depicted in FIGS. 2 and 3 extends from the top surface 148 toward the bottom surface 152. The bottom surface 152 provides a solid substrate on which wafers can be grown in the wafer carrier 142.

FIG. 5 is a bottom plan view of wafer carrier 142 previously described with respect to FIGS. 2 through 4. As shown in FIG. 5, wafer carrier 142 includes a locking feature 164 in the center of bottom surface 152. The locking feature 164 is configured to engage with other components, such as the joint 30 of the spindle 24 previously depicted in FIG. In various embodiments, the locking feature 164 can include, for example, a spline, a chuck, or a lock joint. Those skilled in the art will appreciate that various mechanisms are capable of applying angular momentum from adjacent components to wafer carrier 142.

The bottom surface 152 can be any material and is designed to facilitate heat transfer in embodiments. As previously mentioned, it is desirable in embodiments to transfer heat from a nearby thermal element (such as heating element 34 shown in Figure 1) to the bottom surface 152. Thus, the bottom surface 152 can be a relatively low refractive index material or can be coated with such a material.

The wafer carrier 142 can be formed of any material thereon suitable for epitaxial growth, in embodiments, such as graphite or graphite coated materials. In other embodiments, the materials that make up the wafer carrier 142 can be selected to match the desired lattice settings or dimensions. Likewise, different sized accommodating regions 162 can be used depending on the wafer desired to be grown.

FIG. 6 is a partial perspective view showing an accommodation area 162. Each receiving area 162 includes a side wall 166 that is substantially cylindrical. The bottom of the cylinder formed by side wall 166 is substrate 168. In an embodiment, sidewall 166 may have a depth of approximately 430 [mu]m.

These examples are for illustrative purposes and are not limiting. Additional embodiments are within the scope of the patent application. In addition, although the aspects of the present invention have been described with reference to the specific embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the scope of the present invention as defined by the scope of the claims. .

10‧‧‧(reaction) cabin
12‧‧‧ gas distribution device
14‧‧‧ (reactive gas) source
16‧‧‧ (carrier gas) source
18‧‧‧ (reactive gas) source
20‧‧‧Cooling system
22‧‧‧Exhaust system
24‧‧‧ shaft
26‧‧‧ center axis
28‧‧‧Rotating through device
30‧‧‧Connectors
32‧‧‧Rotary drive mechanism
34‧‧‧ heating elements
36‧‧‧ Entrance
38‧‧‧Front cabin
40, 40'‧‧‧ Doors
42‧‧‧ wafer carrier
44‧‧‧Second wafer carrier
46‧‧‧Ontology
48‧‧‧ top surface
52‧‧‧ bottom surface
54‧‧‧ wafer
56‧‧‧Receiving area
58‧‧‧Temperature Analysis System
60‧‧‧ Temperature monitor

The present invention can be more completely understood in consideration of the following detailed description of various embodiments of the present invention, in which: FIG. 1 is a schematic illustration of an MOCVD processing pod according to an embodiment. 2 is a perspective view of a wafer carrier having 31 accommodating zone configurations, in accordance with an embodiment. 3 is a top plan view of a wafer carrier having 31 accommodating zone configurations, in accordance with an embodiment. 4 is a side view of a wafer carrier having 31 accommodating zone configurations, in accordance with an embodiment. Figure 5 is a bottom plan view of a wafer carrier having 31 accommodating zone configurations, in accordance with an embodiment. 6 is a partial detail view of a wafer carrier having 31 accommodating zone configurations showing a single accommodating zone from a perspective view, in accordance with an embodiment.

142‧‧‧ wafer carrier

148‧‧‧ top surface

162‧‧‧Receiving area

R1, R2, R3‧‧‧ round

Claims (10)

A wafer carrier, comprising: a body having a top surface and a bottom surface disposed opposite to each other; a plurality of accommodating regions defined by the wafer carrier a top surface; a locking feature disposed on the bottom surface for applying angular momentum from the adjacent component to the wafer carrier; the wafer carrier comprising a plurality of accommodating regions including 31 accommodating regions A zone, each zone being arranged along a circle of three circles, wherein each circle of the circle is concentric with one another and concentric with a circular profile formed by the top surface. The wafer carrier of claim 1, wherein: four of the plurality of accommodating regions are arranged around a first one of the three circles; in the plurality of accommodating regions Ten accommodating regions are arranged around a second one of the three circles; and seventeen accommodating regions of the plurality of accommodating regions are arranged around a third one of the three circles. The wafer carrier of claim 2, wherein the first circle is surrounded by the second circle and the second circle is surrounded by the third circle. The wafer carrier of claim 1, wherein the top surface comprises a diameter of about 675 mm. The wafer carrier of claim 1 or 4, wherein each of the plurality of accommodating regions comprises a accommodating region diameter of about 50 mm. The wafer carrier of claim 1 or 4, wherein each of the plurality of accommodating regions comprises a radial wall having a depth of about 430 μm. The wafer carrier of claim 1, wherein the locking feature is disposed at a geometric center of the bottom surface. The wafer carrier of claim 1 or 7, wherein the locking feature is selected from the group consisting of a spline, a chuck, or a lock connector. The wafer carrier of claim 1, wherein the top surface and the bottom surface each comprise a diameter, and the diameter of the top surface is greater than the diameter of the bottom surface. The wafer carrier of claim 1, wherein the wafer carrier is constructed for use in a metal organic chemical vapor deposition system.