CN105280483B

CN105280483B - Central pedestal of integrated two-shaft lifting rotary motor in multi-wafer turntable ALD

Info

Publication number: CN105280483B
Application number: CN201510295764.2A
Authority: CN
Inventors: J·约德伏斯基; K·甘加基德加
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2014-06-05
Filing date: 2015-06-02
Publication date: 2020-10-30
Anticipated expiration: 2035-06-02
Also published as: KR20150140226A; KR102374532B1; KR102374534B1; TW201546948A; KR20170090391A; CN105280483A; TWI665753B

Abstract

The present invention provides an apparatus and method for processing semiconductor wafers that includes a central pedestal having a vacuum capable two-axis lift-rotate motor. The wafer is subjected to a differential pressure between the top and bottom surfaces created by applying a reduced pressure to the wafer backside via an interface with the motor assembly such that sufficient force prevents the wafer from moving during processing.

Description

Central pedestal of integrated two-shaft lifting rotary motor in multi-wafer turntable ALD

Technical Field

Embodiments of the present disclosure generally relate to an apparatus and method for holding a substrate during processing. In particular, embodiments of the present disclosure are directed to apparatus and methods that use differential pressure to hold a substrate on a pedestal under large acceleration forces.

Background

In some CVD and ALD processing chambers, a substrate, also referred to herein as a wafer, is moved relative to a precursor injector and/or heater assembly. If the motion generates an acceleration force greater than the friction force, the wafer may become dislodged, causing damage or related problems. The off-axis positioned wafer can slide on the moving/rotating susceptor at high acceleration/deceleration. The frictional forces derived from the weight of the wafer itself may not be sufficient to hold the wafer on a tool seeking higher throughput.

To prevent the rotational forces from moving the wafer during processing, additional hardware may be used to clamp or clamp the wafer in place. The additional hardware may be expensive, difficult to install, difficult to use, and/or cause damage to the wafer during use.

Accordingly, there is a need in the art for methods and apparatus that can hold a wafer in place during processing to prevent accidental damage to the wafer or hardware.

Disclosure of Invention

One or more embodiments of the present disclosure are directed to a motor assembly including a motor housing having a top and a bottom. A drive shaft extends a distance from the top of the motor housing and has a cavity therein. The first motor is within the motor housing to rotate a drive shaft within the motor housing about a central axis. The second motor is adjacent the bottom of the motor housing and communicates with at least one guide rail within the motor housing to move the first motor and the quill along the central axis.

Additional embodiments of the present disclosure are directed to a motor assembly comprising a motor housing, a drive shaft, a first motor, a second motor, a seal housing, and a water jacket. The motor housing has a top and a bottom. The drive shaft extends a distance from the top of the motor housing. The drive shaft has a cavity therein with at least one channel forming a fluid connection to the cavity. The first motor is within the motor housing to rotate a drive shaft within the motor housing about a central axis. The second motor is adjacent the bottom of the motor housing and communicates with at least one guide rail within the motor housing to move the first motor and the quill along the central axis. A hermetic shell is within the motor housing and has a gas space within the hermetic shell. A sealed housing is positioned about a portion of the drive shaft. The gas space is in fluid communication with the cavity in the drive shaft through the at least one channel. The water jacket is in contact with a lower portion of the drive shaft that is partially surrounded by the seal housing.

Further embodiments of the present disclosure are directed to a process chamber including at least one gas distribution assembly within the process chamber. A susceptor assembly underlies the at least one gas distribution assembly and includes a top surface, a bottom surface, and at least one recess in the top surface for supporting a wafer. The motor assembly includes a motor housing, a drive shaft, a first motor, and a second motor. The motor housing has a top and a bottom. The drive shaft extends a distance from the top of the motor housing and has a cavity in the drive shaft. The first motor is within the motor housing to rotate a drive shaft within the motor housing about a central axis. The second motor is adjacent the bottom of the motor housing. The second motor communicates with at least one guide within the motor housing to move the first motor and the hollow shaft along the central axis to move the base assembly toward or away from the at least one gas distribution assembly. At least one channel extends between a bottom surface of the at least one recess in the base assembly and the cavity in the drive shaft, wherein a vacuum formed in the cavity of the drive shaft is in fluid communication with the recess in the base assembly through the at least one channel.

Drawings

So that the manner in which the above recited features of the present disclosure are attained and can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. The appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIG. 1 illustrates a partial cross-sectional view of a processing chamber according to one or more embodiments of the present disclosure; and

FIG. 2 illustrates a view of a portion of a gas distribution assembly according to one or more embodiments of the present disclosure;

FIG. 3 illustrates a partial cross-sectional view of a processing chamber according to one or more embodiments of the present disclosure;

FIG. 4 illustrates a partial cross-sectional view of a processing chamber according to one or more embodiments of the present disclosure;

FIG. 5 illustrates a perspective view of a groove in a base assembly with a visible vacuum channel according to one or more embodiments of the present disclosure;

FIG. 6 illustrates a cutaway perspective view of a base assembly according to one or more embodiments of the present disclosure;

FIG. 7 illustrates a partial cross-sectional view of a susceptor assembly having a vacuum channel according to one or more embodiments of the present disclosure;

FIG. 8 illustrates a partial cross-sectional view of a susceptor assembly having a vacuum channel according to one or more embodiments of the present disclosure;

FIG. 9 illustrates a partial cross-sectional view of a base assembly according to one or more embodiments of the present disclosure; and

fig. 10 illustrates a cross-sectional view of a motor assembly according to one or more embodiments of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially utilized on other embodiments without further recitation.

Detailed Description

Embodiments of the present disclosure provide methods and apparatus capable of holding a wafer in place during processing to prevent or minimize accidental damage to the wafer and hardware. Embodiments of the present disclosure are directed to apparatus and methods for generating a pressure differential from a unique precursor injector design that is of sufficient magnitude to hold a wafer in place at high rotational speeds. As described in the present specification and the appended claims, the terms "wafer," "substrate," and the like are used interchangeably. In some embodiments, the wafer is a rigid, discrete substrate.

In some spatial ALD chambers, precursors for deposition are injected very close to the wafer surface. To create gas dynamics, the injector channels are independently controlled at higher pressures than the surrounding chamber. By creating a pressure differential between the wafer front side and the wafer back side, a positive pressure can be created that is sufficient to resist the relatively large acceleration forces to maintain the wafer in a positive pressure.

Embodiments of the present disclosure are directed to the use of a pressure differential to hold a substrate (wafer) on a susceptor under large acceleration forces. Large acceleration forces are generated due to high rotational speeds experienced in turntable type processing chambers due to larger batches and processing speeds for higher wafer throughput or higher reciprocation.

In some embodiments, the wafer is placed in a shallow pocket on a susceptor below the implanter component. The susceptor may provide heat transfer, improved gas dynamics, and/or the susceptor may serve as a carrier for the substrate.

Embodiments of the present invention are directed to a susceptor having an angled hole from the inner diameter of the bottom of the susceptor up to the wafer pocket to obtain a vacuum. The susceptor may be connected to a vacuum source by a rotating shaft and a rotating motor below the shaft. If the susceptor is made of Silicon Carbide Coated (SiC) graphite, additional holes may be provided from the top or bottom of the susceptor for better penetration of the SiC coating, for example, spaced every three times the pore size. The excess holes are plugged for vacuum. The graphite plug may be press fit prior to SiC coating, and then the susceptor is coated with SiC. In some embodiments, for more corrosive applications, a threaded SiC coated plug and a second SiC coating on the SiC coated base may be applied in order to obtain better graphite sealing with SiC.

Fig. 1 illustrates a portion of a processing chamber 100 according to one or more embodiments of the present disclosure. The processing chamber 100 includes at least one gas distribution assembly 110 to distribute the reactant gases to the chamber. The embodiment shown in FIG. 1 has a single gas distribution assembly 110, but those skilled in the art will appreciate that any suitable number of gas distribution assemblies may be present. There may be multiple components with spacing between the components, or little spacing between the components. For example, in some embodiments, there may be multiple gas distribution assemblies 110 positioned adjacent to each other so that the wafer 120 effectively experiences a consistent and repetitive gas flow.

Although various types of gas distribution assemblies 110 (e.g., showerheads) can be used, for ease of description, the embodiment shown in FIG. 1 shows several substantially parallel gas channels 111. As used in this specification and the appended claims, the term "substantially parallel" means that the axes of extension of the gas channels 111 extend in the same general direction. The parallelism of the gas channels 111 may be slightly insufficient. However, those skilled in the art will appreciate that the carousel-type processing chamber may rotate about a central axis that is offset from the central axis of the wafer. In this configuration, a substantially non-parallel gas channel 111 may be useful. Referring to fig. 2, the gas distribution assembly 110 may be a pie-shaped segment in which the gas channels 111 extend from an inner edge 115 of the pie toward an outer edge 116 of the pie. The shape of the gas channel 111 may also be different. In some embodiments, the gas channel 111 has a substantially uniform width along the length of the channel extending from the inner edge 115 to the outer edge 116. In some embodiments, the width W of the gas channel 111 increases along the length L of the channel extending from the inner edge 115 to the outer edge 116. This is shown in fig. 2, where the gas channel 111 has a smaller width near the inner edge 115 and a wider width near the outer edge 116. According to some embodiments, the aspect ratio of the width variation may be equal to the radial difference in position so that the edge of each channel extends from the same point. This results in all points of the wafer having approximately equal residence times under the gas channels. In other words, each channel width may vary according to the distance from the susceptor rotation center.

Referring back to fig. 1, the plurality of gas channels 111 may include at least one first reactive gas a channel, at least one second reactive gas B channel, at least one purge gas P channel, and/or at least one vacuum V channel. The gases flowing from the first reactive gas a channel, the second reactive gas B channel, and the purge gas P channel are directed toward the top surface 121 of the wafer 120. The airflow is shown by arrows 112. Some of the gas flow moves horizontally across the surface 121 of the wafer 120 and up and out of the processing region through the vacuum V-channels, as indicated by arrows 113. The substrate moving from left to right will be exposed to each process gas in turn, forming a layer on the substrate surface. The substrate may be in a single wafer processing system wherein the substrate is moved in a reciprocating motion beneath the gas distribution assembly; or the substrates may be in a turntable type system in which one or more substrates are rotated about a central axis passing beneath the gas channels. Fig. 2 illustrates a portion of a carousel-type system according to one or more embodiments of the present disclosure. For the orientation of fig. 2, the process gas can be considered to flow out of the plane of the drawing sheet. The substrate following path 127 will be exposed to each process gas in turn. Path 127 is shown as enclosing an arc of about 90 °, but those skilled in the art will appreciate that path 127 may be any length and any portion of an arc-shaped path.

Fig. 3 shows a cross-sectional view of one or more embodiments of the present disclosure. The cross-sectional portion of the gas distribution assembly 110 can be envisioned to be taken along the length of the purge gas port of fig. 2, for example. The susceptor assembly 130 may be positioned below the gas distribution assembly 110. The base assembly 130 includes a top surface 131, a bottom surface 132, and at least one recess 133 in the top surface 131. The recess 133 may be any suitable shape and size depending on the shape and size of the wafer 120 being processed. In the illustrated embodiment, the groove 133 has a two-step region 134 around the outer peripheral edge of the groove 133. The stepped region 134 may be sized to support the outer peripheral edge 122 of the wafer 120. The amount of the outer peripheral edge 122 of the wafer 120 supported by the stepped region 134 may vary depending on, for example, the thickness of the wafer and the presence of features already on the back side 123 of the wafer.

In some embodiments, the recess 133 in the top surface 131 of the susceptor assembly 130 may be sized such that the wafer 120 supported in the recess 133 has a top surface 121 that is substantially coplanar with the top surface 131 of the susceptor assembly 130. As used in this specification and the appended claims, the term "substantially coplanar" means that the top surface of the wafer is coplanar with the top surface of the susceptor assembly within a tolerance of ± 0.2 mm. In some embodiments, the top surface of the wafer is coplanar with the top surface of the susceptor assembly within a tolerance of ± 0.15mm, ± 0.10mm, or ± 0.05 mm.

The bottom 135 of the recess has at least one channel 140 that extends from the bottom of the recess 133 through the susceptor assembly 130 to the drive shaft 160 of the susceptor assembly 130. The channel 140 may be any suitable shape and size, and the channel 140 provides fluid communication between the recess 133 and the drive shaft 160. The channels 140 shown in fig. 3 are angled with respect to the groove bottom. In some embodiments, the channel 140 includes more than one branch in fluid communication with the groove. For example, a major portion of the channel 140 may extend parallel to the top or bottom surface of the base, and a major portion of the channel 140 may be connected to a second branch that turns with respect to the major portion of the channel. The drive shaft 160 may be connected to a vacuum source 165, which vacuum source 165 creates a region of reduced pressure (referred to as a vacuum) within the cavity 161 of the drive shaft 160. As used in this specification and the appended claims, the term "vacuum" as used in this context means a region having a pressure lower than the pressure of the process chamber. In some embodiments, the vacuum, or reduced pressure region, has a pressure of less than about 50 torr, or less than about 40 torr, or less than about 30 torr, or less than about 20 torr, or less than about 10 torr, or less than about 5 torr, or less than about 1 torr, or less than about 100 mtorr, or less than about 10 mtorr.

The cavity 161 may act as a vacuum chamber so that if there is a loss of external vacuum, the vacuum within the cavity 161 may be maintained at a reduced pressure. The channels 140 are in communication with the cavity 161 so that a vacuum within the cavity 161 can draw the backside 123 of the wafer 120 through the channels 140.

In the case of a vacuum or partial vacuum in the recess 133 below the wafer 120, the pressure in the reaction region 102 above the wafer 120 is greater than the pressure in the recess 133. This differential pressure provides sufficient force to prevent the wafer 120 from moving during processing. In one or more embodiments, the pressure in the recess 133 below the wafer 120 is lower than the pressure above the wafer 120 and the pressure in the processing chamber 100.

The pressure applied to the top surface 121 of the wafer 120 from the gas flow emitted by the gas distribution assembly 110, along with the reduced pressure below the wafer, helps hold the wafer in place. This has particular application in a turntable type processing chamber, where the wafer is offset from and rotated about a central axis in the turntable type processing chamber. The centrifugal force associated with the rotation of the susceptor assembly may cause the wafer to slide off the central axis. The differential pressure at the top side of the wafer relative to the bottom side of the wafer helps prevent wafer movement due to the pressure of the gas from the gas distribution assembly relative to the pressure applied to the back side of the wafer by the vacuum. The gas channels of the gas distribution assembly can be controlled simultaneously (e.g., simultaneously controlling all output channels-the reactant gas channel and the purge channel), in groups (e.g., simultaneously controlling all first reactant gas channels), or independently (e.g., the leftmost channel is independently controlled from adjacent channels, etc.). As used in this specification and the appended claims, the terms "output channel," "gas injector," and the like are used interchangeably to mean a slot, channel, or nozzle type opening through which gas is injected into a processing chamber. In some embodiments, the first reactive gas channel, the second reactive gas channel, and the at least one purge gas channel are independently controlled. The independent control may be used to provide a positive pressure on the top surface of the wafer that is located in the recess of the submount assembly. In some embodiments, each individual first reactant gas injector, second reactant gas injector, purge gas injector, and pump channel may be individually and independently controlled.

The differential pressure between the top surface of the wafer and the bottom surface of the wafer can be adjusted by varying parameters such as the pressure of the gas from the gas distribution assembly, the flow rate of the gas from the gas distribution assembly, the distance between the gas distribution assembly and the wafer or susceptor surface, and the vacuum pressure described above. As used in this specification and the appended claims, differential pressure is a measure of the pressure above the wafer relative to the pressure below the wafer. The pressure above the wafer is the pressure applied to the wafer surface or the pressure in the reaction region 102 of the process chamber 100. The pressure under the wafer is the pressure in the recess, the vacuum pressure in the susceptor assembly 130, and the pressure on the bottom surface. The magnitude of the differential pressure can directly affect the degree to which the wafer is clamped. In some embodiments, the differential pressure between the top surface 121 of the wafer 120 and the bottom surface 123 of the wafer 120 is greater than about 15 torr, or greater than about 10 torr, or greater than about 5 torr. In one or more embodiments, the differential pressure between the top surface 121 of the wafer 120 and the pressure in the recess 133 corresponds to a clamping force that is large enough to hold a 300mm wafer at a bolt center radius of about 320mm and a rotational speed of about 200 rpm.

In some embodiments, as shown in fig. 3, the processing chamber 100 includes a heating assembly 150. The heating assembly may be located at any suitable location within the processing chamber including, but not limited to, below the susceptor assembly 130 and/or on an opposite side of the susceptor assembly 130 from the gas distribution assembly 110. The heating assembly 150 provides sufficient heat to the process chamber to raise the temperature of the wafer 120 to a temperature useful for the process. Suitable heating components include, but are not limited to, resistive heaters and radiant heaters (e.g., a plurality of lamps) that direct radiant energy toward the bottom surface of the susceptor assembly 130.

The distance between the gas distribution assembly 110 and the top surface 121 of the wafer 120 can be adjusted and can have an effect on the differential pressure and the gas flow efficiency from the gas distribution assembly. If the distance is too large, the gas flow may diffuse out before encountering the wafer surface, resulting in a lower differential pressure and an inefficient atomic layer deposition reaction. If the distance is too small, the gas flow may not be able to flow through the surface to the vacuum holes of the gas distribution assembly and a large differential pressure may be created. In some embodiments, the gap between the wafer surface and the gas distribution assembly is in the range of about 0.5mm to about 2.0mm, or in the range of about 0.7mm to about 1.5mm, or in the range of about 0.9mm to about 1.1mm, or about 1.0 mm.

The groove 133 shown in figure 3 supports the wafer 120 around the outer peripheral edge 122 of the wafer 120. Depending on the thickness, rigidity, and/or vacuum pressure in the groove 133, this arrangement may result in successful clamping of the wafer, preventing or minimizing wafer movement during rotation or movement of the susceptor assembly 130. However, if the wafer is not thick or rigid, or the vacuum pressure in groove 133 is too low, then wafer 120 may deflect such that the center portion of the wafer is further away from gas distribution assembly 110 than the outer peripheral edge 122 of wafer 120.

Figure 4 illustrates another embodiment that helps prevent wafer deflection by providing a larger support surface area. Here, the susceptor assembly 130 supports the wafer 120 across a substantial portion of the back side 123. This figure shows a cross-sectional view of the susceptor assembly. The central portion 137 of the base assembly 130 is not free floating, but rather is attached to the remainder of the base in a plane different from the cross-sectional view. The channel 140 extends from the drive shaft 160, or from a cavity 161 within the drive shaft 160, toward the recess 133. The channel 140 is connected to a channel 146, the channel 146 extending toward the top surface 131 of the base assembly 130. The vacuum clamps the wafer 120 to the susceptor assembly 130 by the vacuum passing through the channels 146 and the channels 140.

Fig. 5 shows a perspective view of a base assembly 130 similar to that of fig. 4. The susceptor assembly 130 is shown having a recess 133, the recess 133 having a relatively large stepped region 134 to support the outer peripheral edge 122 of the wafer (not shown). The groove 133 includes a large channel 140 connecting the channel 146 to the vacuum in the drive shaft. The channel is shown shaped like a capital letter theta and provides a ring of channels having channel portions (or cross-slots) extending across the diameter of the ring of channels. The central portion 137 of the susceptor assembly 130 may be approximately coplanar with the stepped region 134 such that the central portion 137 and the stepped region 134 simultaneously support the wafer.

Fig. 6 illustrates a perspective view of a base assembly 130 according to one or more embodiments of the present disclosure. Here, the channel 140 extends from the drive shaft 160 towards the groove 133 connecting the cavities 161, with the channels 146 in the groove, said cavities 161 acting as vacuum plenums. The channel 140 has a plurality of holes 147 that connect the top surface 131 of the base assembly 130 with the channel 140. In some embodiments, there is at least one hole extending from one of the top surface 131 of the base assembly 130 and the bottom surface 132 of the base assembly 130 to the channel 140. These holes 147 may be created (e.g., drilled) during the manufacture of the base assembly to allow the interior of the channel 140 to be coated. For example, in some embodiments, the susceptor assembly 130 has a silicon carbide coating. The susceptor assembly of some embodiments is silicon carbide coated graphite. The holes 147 allow silicon carbide to be coated over the channels 140 and subsequently sealed with plugs 148. The plug may be made of any suitable material including, but not limited to, silicon carbide coated graphite, a material having a silicon carbide coating and graphite, and after the plug 148 has been inserted into the bore 147, the base assembly may be coated again with silicon carbide to provide additional sealing of the bore 147. Plug 148 may be press fit (e.g., friction fit) connected to bore 147 by complementary threads, or connected by some other mechanical connection (e.g., epoxy).

During preparation of the silicon carbide coated susceptor assembly 130, the apertures 147 provide useful passages for the silicon carbide to coat the channels 140. The size and spacing of the holes 147 may have an effect on the efficiency of the coating. The apertures 147 may be spaced at increments of aperture size. For example, if the diameter of the holes is 5mm, the spacing may be 5x mm, where x is any suitable value. For example, the spacing may be 1, 2, 3, 4, 5, 6,7, 8, 9, or 10 times the pore size. Apertures 147 may be located at any suitable point along the length of channel 140, and apertures 147 need not be evenly distributed across the length of channel 140. As shown in fig. 6, the apertures 147 converge toward the interior of the base assembly 130, with the channel 140 being remote from the top surface 131 of the base assembly 130.

The channel 140 may be used to supply a vacuum to the recess 133 to clamp the wafer 120. However, when the wafer is processed, the vacuum may be too strong to easily remove the processed wafer from the recess. The channels 140 may also be used to provide a gas flow toward the backside of the wafer 120 for ease of wafer removal. Thus, a positive pressure is provided to the backside of the wafer to allow the wafer to be easily removed from the susceptor assembly.

Fig. 9 shows a schematic view of a base assembly according to one or more embodiments of the present disclosure. Here, the recess 133 is connected to the channel 140, the channel 140 opening into a cavity 161 within the drive shaft. Valve 171 is located within passage 140. Valve 171 may allow fluid connection between channel 140 and cavity 161 through connector 141. If a vacuum, or area of reduced pressure, is formed in cavity 161, a valve may connect cavity 161 to groove 133 through connector 141 and channel 140. Valve 171 may be switched to interrupt the fluid connection between channel 140 and cavity 161. The valve may be set to a closed position, isolating the passage 140; or to a position in which a connection is made between the channel 140 and the de-chucking plenum 173 by the connector 142. The de-chucking plenum 173 is shown in fluid communication with a de-chucking gas source 175. The strip clamp gas source 175 may comprise any suitable gas including, but not limited to, nitrogen, argon, helium, or an inert gas.

Fig. 7 illustrates another embodiment of the base assembly 130. Here, the channel 140 extends from the outer edge of the base member 130 approximately parallel to the bottom of the groove 133. Plug 148 closes the end of channel 140. The first portion 140a of the channel turns to the second portion 140b and extends into the drive shaft 160. The channel 146 extends from the channel 140 into the bottom of the recess 133 around the center of the recess 133. Several abutments 149 extend from the bottom 135 of the groove 133 to the height of the first step in the stepped region 134. Several standoffs 149 provide support for the wafer to prevent or minimize bowing. The pedestals 149 are positioned around the groove with a gap therebetween to allow the vacuum to affect the entire groove.

Fig. 8 illustrates another embodiment of the base assembly 130. Here, the groove comprises a number of steps that are progressively larger than the height of the initial step region 134. The first stepped region 134a has a first height. The second stepped region 134b has a second height greater than the first height. The third stepped region 134c has a third height greater than the second height. Although three stepped regions are shown, one skilled in the art will appreciate that there may be any number of stepped regions. In the illustrated embodiment, the heights of the first, second, and third stepped regions increase toward the center of the recess. In some embodiments, the height of the individual stepped regions may be different so that some regions have a greater height than other regions regardless of the position of the region relative to the center of the groove.

The diameter and height of the individual stepped regions may be different. In some embodiments, the first stepped region 134a has a height in a range of about 10 μm to about 90 μm relative to the initial stepped region 134. When the wafer 120 is placed on the initial stepped region 134a, the first height is measured relative to the initial stepped region 134 even though the initial stepped region 134 is below the level of the top surface 131 of the susceptor assembly 130. In some embodiments, the first height is in the range of about 20 μm to about 80 μm, or in the range of about 30 μm to about 70 μm, or in the range of about 40 μm to about 60 μm.

In the embodiment shown in fig. 8, the second stepped region 134b of some embodiments has a height in the range of about 35 μm to about 115 μm, and the height of the second stepped region 134b is greater than the height of the first stepped region 134 a. In some embodiments, the second stepped region 134b has a height in a range of about 45 μm to about 105 μm, or in a range of about 55 μm to about 95 μm, or in a range of about 65 μm to about 85 μm.

In the embodiment shown in fig. 8, the third stepped region 134c has a height in the range of about 60 μm to about 140 μm, and the height of the third stepped region 134c is greater than the height of the second stepped region 134 b. In some embodiments, the third step region 134c has a height in the range of about 70 μm to about 130 μm, or in the range of about 80 μm to about 120 μm, or in the range of about 90 μm to about 110 μm.

The height of the pedestal 149 may vary depending on the height of the particular stepped region in which the pedestal is located. Referring to fig. 8, the pedestals in the third step area are higher than the pedestals in the first step area. The pedestal of some embodiments has a height sufficient to cause the top of the pedestal to be substantially coplanar with the initial stepped region such that the wafer located in the recess is substantially coplanar with the top surface of the susceptor assembly.

A vacuum source 165 may be connected to the cavity 161 through a valve 162. In the presence of a loss of vacuum from the vacuum source 165, the valve 162 may be used to isolate the cavity 161 from the vacuum source 165. This allows the cavity 161 to act as a vacuum plenum so that the wafer on the susceptor assembly remains clamped until such time as the vacuum source is reconnected or repaired.

Each of the individual grooves 133 in the base assembly 130 may include a separate channel 140 and valve 171. This allows each individual groove 133 to be isolated from the vacuum in the cavity 161. For example, the processed wafer 120 may be rotated to a load/unload region of the process chamber. The valve 171 may be closed or switched to the de-chucking plenum 173 to create a positive pressure on the backside of the wafer, allowing the robot to pick up the wafer. After picking up the wafer, the valve may be closed so that the pressure in the recess 133 will be equal to the pressure of the chamber. A new wafer may be placed in the recess and the valve 171 switched back to allow fluid connection with the cavity 161 to clamp the new wafer.

According to one or more embodiments herein, a central pedestal on a turntable pedestal driven by an integrated two-axis motor for raising and lowering and rotating the pedestal may also be used to incorporate, for example, nitrogen or vacuum for clamping/de-clamping wafers. In addition, some embodiments use water, or coolant, during plasma processing to maintain a hermetic seal and use the wafer's motor magnets and electrical ground.

Referring to fig. 10, a schematic diagram of a motor assembly 200 for one or more embodiments of the present disclosure is provided. The motor assembly 200 has a motor housing 202, the motor housing 202 having a top 203 and a bottom 204. The illustrated motor assembly 200 includes a base 206, which base 206 may be integrally formed with the side 207 of the housing 202 or may be a separate element.

The motor assembly 200 includes a drive shaft 210, the drive shaft 210 coming from the top 203 of the motor housing 202. The drive shaft 210 includes a body 213 and a cavity 212 in the body. The cavity 212 may be in fluid communication with a gas or vacuum source and may act as a plenum as described further below.

The drive shaft 210 may be made of any suitable material capable of supporting the susceptor assembly while maintaining the cavity within the susceptor assembly during wafer processing. In some embodiments, the drive shaft 210 is made of a material comprising stainless steel. The size of the drive shaft 210 may vary depending on, for example, the size and weight of the base assembly and other components supported on the base assembly.

The drive shaft 210 extends a distance D from the motor housing 202. This distance D may be changed or varied before, during and/or after processing. In use, the motor assembly 200 supports and rotates the base assembly. The distance D that the drive shaft 210 extends from the motor housing 202 is directly related to the vertical height of the susceptor and any wafer supported on the susceptor.

The drive shaft 210 is in contact with a first motor 220 located within the motor housing 202. The first motor 220 rotates the drive shaft 210 within the motor housing 202 about a central axis 211. The drive shaft 210 may be connected to the first motor by contact, friction, or hardware. In the embodiment shown in fig. 10, the drive shaft 210 is connected to a motor/shaft interface 222, which motor/shaft interface 222 is connected to a first motor 220. The motor/shaft interface 222 may be any suitable material including, but not limited to, stainless steel or aluminum. The material of the motor/shaft interface 222 may have a coefficient of expansion similar to the coefficient of expansion of the drive shaft 210 or the seal housing 240, as described below. The first motor 220 may be any suitable type of motor capable of rotating the drive shaft 210. In some embodiments, the first motor 220 is a direct drive motor that is directly coupled to the hollow drive shaft 210.

The direct drive motor may be raised and lowered using a combination of a ball screw motor and two symmetrical mechanical guides. In some embodiments, the ball screw is positioned as close to center as possible to minimize shaft tilt. The second motor 230 is positioned adjacent the bottom 204 of the motor housing 202. The second motor 230 may be any suitable type of motor including, but not limited to, a ball screw motor. In the embodiment shown in fig. 10, the second electric motor 230 is located outside the motor housing 202, but the second electric motor 230 may also be located inside the motor housing. The second motor 230 communicates with at least one guide rail 232 within the motor housing 202 to move the first motor 220 and the drive shaft 210 along the length of the central shaft 211. Movement along the length of the central shaft 211 changes the distance D that the drive shaft 210 extends from the top 203 of the motor housing 202. Nut 234 is positioned along screw 236 of the second motor. Rotation of screw 236 causes nut 234 to move along the length of screw 236.

The second motor 230 may be located anywhere relative to the central axis 211 of the assembly 200. In some embodiments, the second motor 230 is positioned as close as possible to the central shaft 211 to minimize the rack of the motor assembly during movement. In one or more embodiments, the motor assembly is circular and the functional elements (e.g., screws, nuts, and rails) of the second motor 230 are located within 50% of the radius of the motor 220 as measured from the central shaft 211.

In some embodiments, there are at least two symmetrical guide rails 232 within the motor housing 202. The two rails may be located on either side of the central axis 211 or on either side of the screw 236. For example, the monorail shown in FIG. 10 may be two pieces that nut 234 contacts simultaneously.

The motor assembly 200 may also include a seal housing 240 for a dynamic seal assembly on a z-axis theta motor that provides a vacuum channel for a fast rotating drive shaft 210 having an aperture on its side. A sealed housing 240 may be located within the motor housing 202 and around at least a portion of the drive shaft 210. The sealed housing 240 of some embodiments is in fluid communication with one or more of a vacuum source 241 or a gas source (not shown). A vacuum source 241 or gas source may be connected to the sealed housing through opening 242. In some embodiments, the sealed housing 240 includes a gas space 243 for holding a gas or vacuum. When the vacuum source 241 is connected to the sealed enclosure 240, the gas space 243 is under vacuum. The gas space 243 may hold a gas when a gas source (not shown) is connected to the sealed housing 240.

The drive shaft 210 as shown in fig. 10 may comprise at least one channel 215, said at least one channel 215 forming a fluid connection between the cavity 212 of the drive shaft and the gas space 243 of the sealed housing 240. The seal housing 240 contains at least one O-ring 245 to form a hermetic seal between the seal housing 240 and the drive shaft 210. In the embodiment shown in fig. 10, there are two O-rings 245 shown positioned above and below the channel 215. O-ring 245 helps ensure a hermetic seal while allowing gas to flow from cavity 212 through channel 215 into gas space 243 of seal housing 240 and ultimately out to vacuum source 241. When a gas source is used instead of a vacuum source, the gas flow path is reversed.

In some embodiments, the at least one channel 215 in the drive shaft extends substantially perpendicular to the central axis 211. As used in this specification and the appended claims, the term "substantially perpendicular" as used in this respect means that the axis of the channel 215 is at an angle greater than or equal to about 45 degrees relative to the central axis 211. In some embodiments, the channel axis is at an angle greater than about 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, or 85 degrees relative to the central axis 211. In one or more embodiments, the angle of the channel axis relative to the central axis is in the range of about 85 to about 90 degrees, or in the range of about 80 to about 90 degrees.

The number of channels 215 formed in the drive shaft 210 may be any suitable number. In some embodiments, 1, 2, 3, 4, 5, 6,7, 8, or more separate channels extend through the body 213 of the drive shaft 210, forming a fluid connection between the cavity 212 and the gas space 243. In some embodiments, there are four laterally drilled channels through the body 213. In one or more embodiments, a single area 20mm diameter vacuum is supplied to the base and provided in a circular pocket between the shaft's lip seal (top O-ring 245) and square seal (lower O-ring 245), and then receives the shaft through four side holes or channels. In some embodiments, the cavity in the drive shaft 210 has a diameter of 100mm, and the cavity can be used as a vacuum reservoir for holding the rest of the wafer clamped during wafer exchange.

Vacuum isolation may be assisted or achieved using a combination of stainless steel bellows 260 and/or a dynamic lip seal (O-ring 245) contained in the seal housing 240. To further isolate the gas space 243 of the sealed housing 240 from the processing environment, a bellows 260 is positioned between the sealed housing and the top 205 of the motor housing 202. The top 205 of the motor housing 202 may be attached to the sides 207 of the motor housing using any suitable method, including. The top 205 may be a separate element mechanically attached to the side 207 or may be integrally formed with the side 207. The bellows 260 expands and contracts along the length of the central shaft 211 during movement of the motor 220, the drive shaft 210, and the seal housing 240.

The rotor shaft supporting the base may be cooled to prevent heat from being conducted to the directly driven motor magnet and causing demagnetization. The first motor 220, which may be a direct drive motor, may be water cooled by flowing water through the sealed housing 240. In addition, according to embodiments, because the susceptor is often heated to process temperatures of up to 550 ℃, the bottom end of the drive shaft 210 is cooled to prevent damage to the dynamic seals and motor magnets due to overheating. This cooling is accomplished by attaching, contacting or bolting a water swivel joint, or water jacket 270, below the drive shaft 210, wherein water flows up to the seal through the press-fit connection of the water jacket to the shaft. In some embodiments, water jacket 270 contacts the bottom of drive shaft 210 through motor/shaft interface 222. The water jacket 270 may be connected to a lower portion of the drive shaft 210, but simple contact of the water jacket 270 and the drive shaft 210 may be sufficient to cool the drive shaft 210. Water jacket 270 may also rotate, or may remain stationary, during rotation of drive shaft 210. In some embodiments, the seal housing 240 is positioned around a portion of the water jacket 270.

Although the coolant is referred to as a water jacket, one skilled in the art will appreciate that any type of coolant may be used. For example, automotive antifreeze can be used in place of water. The water jacket 270 is typically made of a material that is a good conductor of heat. In some embodiments, the water jacket is made of aluminum.

In the embodiment shown in fig. 10, the water jacket 270 is connected to the rotary joint 272 by a jacket/joint interface 274. Rotary joint 272 may remain stationary during rotation of drive shaft 210 while water jacket 270 rotates about drive shaft 210. This may be accomplished by flowing a coolant (gas or liquid) through an inlet pipe 275 into the fixed rotary union 272. The coolant then flows up to the jacket/fitting interface 274, where the tubes connect to corresponding tubes in the water jacket 270, and then the coolant flows out of the outlet tube 276.

An electrical multi-conductor slip ring may be bolted under the water swivel to draw the wires up into the base. The electrical connection may be made from the base, down through the drive shaft 210 through a slip ring mounted to the bottom of the shaft. The slip ring and motor/shaft interface 222 (also referred to as a motor/shaft joint) may be the same element or different elements. A plurality of thermocouple wires for checking the susceptor temperature in a plurality of regions and a plurality of wires for grounding the wafer on the susceptor may penetrate the driving shaft 210, the water jacket 270 through the feeding guide 277.

Some embodiments of the present disclosure are directed to a base assembly that includes a motor assembly 200 (such as the motor assembly of fig. 10) and a base that communicates with a top portion 217 of a drive shaft 210. In some embodiments, torque plate 280 is connected to top 217 of drive shaft 210. The torque plate 280 forms an interface between the drive shaft 210 and the base assembly 130. In some embodiments, as shown in fig. 10, a reflective plate 282 is positioned between the torque plate 280 and the base assembly 130. In some embodiments, the heat from the base assembly 130 is gradually reduced using a plurality of stainless steel plates (reflective plates 282) stacked in parallel. Heat from the heater around the shaft (see fig. 3) can be reflected back using a 17-4PH steel reflector shield around the drive shaft, keeping the shaft cool. In some embodiments, the residual heat conducted through the base is reduced by water cooling the shaft with a water jacket as described above using a water swivel below the shaft. The water, or coolant, may be achieved by gun drilling in the thickness of the drive shaft, or by bolting a water swivel joint under a press-fit aluminum water jacket to the motor shaft.

In some embodiments, a bevel hole is provided from the inner diameter of the base of the susceptor up to each wafer pocket for clamping/dechucking. The angled holes may be connected to the hollow drive shaft at high temperatures using a finish plate without a face seal to prevent vacuum leakage. In the event of loss of external vacuum, the hollow shaft may act as a vacuum plenum.

In some embodiments, as seen in fig. 5 and 6, the base member 130 includes a plurality of grooves 133 in the top surface 131 of the base member 130. As shown in fig. 6-8, a plurality of channels 140 extend from the cavity 212 of the drive shaft 210 to the recess 133 in the base assembly 130. In some embodiments, as shown in fig. 9, the channel 140 may comprise a valve in fluid communication with the channel. Multi-zone vacuum clamping enables independent control of each wafer pocket on the turntable, which facilitates wafer exchange. Each vacuum region is connected through a rotor shaft supporting the pedestal, which may be a conduit for various fluids and feeds up to the pedestal, e.g., nitrogen gas for purging or wafer removal clamping; a multi-zone vacuum may be applied for clamping.

The substrate used in embodiments of the present disclosure may be any suitable substrate. In a detailed embodiment, the substrate is a rigid, discrete, and generally planar substrate. As used in this specification and the appended claims, the term "discrete" when referring to a substrate means that the substrate has a fixed dimension. The substrate of a particular embodiment is a semiconductor wafer, such as a 200mm or 300mm diameter silicon wafer.

As used in this specification and the appended claims, the terms "reactive gas," "reactive precursor," "first precursor," "second precursor," and the like refer to a gas or gaseous species capable of reacting with a substrate surface or a layer on a substrate surface.

In some embodiments, one or more layers may be formed during a Plasma Enhanced Atomic Layer Deposition (PEALD) process. In some processes, the use of a plasma provides sufficient energy to promote species to excited states where surface reactions become good and possible. The introduction of the plasma into the process may be continuous or pulsed. In some embodiments, sequential pulses of precursor (or reactant gas) and plasma are used to process a layer. In some embodiments, the reactants may be ionized locally (i.e., within the processing region) or remotely (i.e., outside of the processing region). In some embodiments, remote ionization may occur upstream of the deposition chamber so that ions or other energetic or luminescent species do not come into direct contact with the deposited film. In some PEALD processes, plasma is generated from outside the process chamber, such as by a remote plasma generator system. The plasma may be generated via any suitable plasma generation process or technique known to those skilled in the art. For example, the plasma may be generated by one or more of a Microwave (MW) frequency generator or a Radio Frequency (RF) generator. The frequency of the plasma may be tuned depending on the particular reactive species being used. Suitable frequencies include, but are not limited to, 2MHz, 13.56MHz, 40MHz, 60MHz, and 100 MHz. Although a plasma may be used during the deposition processes disclosed herein, a plasma may not be necessary. Indeed, other embodiments relate to deposition processes under very mild conditions without plasma.

According to one or more embodiments, the substrate is subjected to a treatment before and/or after the layer is formed. This process may be performed in the same chamber or in one or more separate processing chambers. In some embodiments, the substrate is moved from the first chamber to a separate second chamber for further processing. The substrate may be moved directly from the first chamber to the separate processing chamber, or the substrate may be moved from the first chamber to one or more transfer chambers and then moved to the separate processing chamber. Thus, the processing device may comprise a plurality of chambers in communication with the transfer station. Such devices may be referred to as "cluster tools" or "cluster systems," among others.

Generally, a cluster tool is a modular system comprising a plurality of chambers that perform various functions including substrate center finding and orientation, degasing, annealing, deposition, and/or etching. According to one or more embodiments, a cluster tool includes at least a first chamber and a central transfer chamber. The central transfer chamber may house a robot that may shuttle substrates between or among the processing chambers and the load lock chamber. The transfer chamber is typically maintained under vacuum conditions and provides an intermediate stage for reciprocating transfer of substrates from one chamber to another and/or to a load lock chamber located at the front end of the cluster tool. Two well known clustering tools that may be suitable for this case are the Centura and Endura clustering tools available from Applied Materials, inc. Details of one such Staged Vacuum substrate Processing Apparatus are disclosed in U.S. Pat. No. 5,186,718 entitled "Staged-Vacuum Wafer Processing Apparatus and Method" issued on 16.2.1993 by Tepman et al. However, the precise arrangement and combination of chambers may be varied for the purpose of performing a particular step of the process as described herein. Other processing chambers that may be used include, but are not limited to, Cyclical Layer Deposition (CLD), Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), etching, pre-cleaning, chemical cleaning, thermal processing such as Rapid Thermal Processing (RTP), plasma nitridation, degas, orientation, hydroxylation, or other substrate processes. By performing the processes in a chamber on the cluster tool, contamination of the surface of the substrate with atmospheric impurities and lack of oxidation can be avoided prior to deposition of subsequent films.

According to one or more embodiments, the substrate is continuously under vacuum conditions or "load-lock" conditions and is not exposed to ambient air as the substrate moves from one chamber to the next. The transfer chamber is thus under vacuum and "vacuumed" under vacuum pressure. The inert gas may be present in the processing chamber or the transfer chamber. In some embodiments, an inert gas is used as a purge gas to remove some or all of the reactants after forming a silicon layer on the substrate surface. In accordance with one or more embodiments, a purge gas is injected at the outlet of the deposition chamber to prevent reactants from moving from the deposition chamber to the transfer chamber and/or additional processing chambers. Thus, the flow of inert gas forms a curtain at the chamber outlet.

The substrates may be processed in a single substrate deposition chamber, wherein a single substrate is loaded, processed, and unloaded, followed by processing of another substrate. Substrates may also be processed in a continuous manner like a conveyor system, where multiple substrates are loaded into a first portion of the chamber, moved through the chamber, and unloaded from a second portion of the chamber, respectively. The shape of the chamber and associated conveyor system may form a straight path or a curved path. Additionally, the processing chamber may be a carousel in which multiple substrates are moved about a central axis and exposed to deposition, etching, annealing, cleaning, etc. processes throughout the carousel path.

During processing, the substrate may be heated or cooled. This heating or cooling may be accomplished by any suitable method, including, but not limited to, changing the temperature of the substrate support and flowing a heating or cooling gas to the substrate surface. In some embodiments, the substrate support includes a heater/cooler that can be controlled to conductively alter the temperature of the substrate. In one or more embodiments, the gases used (reactive or inert) are heated or cooled to locally change the substrate temperature. In some embodiments, a heater/cooler is located within the chamber adjacent the substrate surface to convectively change the substrate temperature.

The substrate may also be fixed or rotated during processing. The rotating substrate may rotate continuously or in discrete steps. For example, the substrate may be rotated throughout the process, or the substrate may be rotated by a small amount between exposures to different reactive or purge gases. Rotating the substrate (continuously or stepwise) during processing can help produce more uniform deposition or etching by minimizing effects such as local variability in gas flow geometry.

Although the present disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made in the methods and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure include modifications and variations that are within the scope of the appended claims and equivalents of those claims.

Claims

1. An electric motor assembly comprising:

a motor housing having a top and a bottom;

a drive shaft extending a distance from the top of the motor housing and having a cavity therein;

a first motor within said motor housing to rotate said drive shaft within said motor housing about a central axis; and

a second motor adjacent to the bottom of the motor housing and in communication with at least one guide rail within the motor housing to move the first motor and the drive shaft along the central axis;

a sealed housing within the motor housing, the sealed housing positioned around a portion of the drive shaft;

wherein the drive shaft comprises at least one channel forming a fluid connection between the cavity of the drive shaft and the seal housing, wherein the seal housing is in fluid communication with a vacuum source.

2. The motor assembly of claim 1 wherein said at least one channel extends in a direction substantially perpendicular to said central axis.

3. The motor assembly of claim 1 wherein there are four channels.

4. The motor assembly of claim 1, wherein the seal housing includes an O-ring for forming a hermetic seal between the seal housing and the drive shaft.

5. The motor assembly of claim 1, wherein the first motor is a direct drive motor.

6. The motor assembly of claim 1 wherein the second motor is a ball screw motor and there are at least two symmetrical guide rails for moving the drive shaft and first motor.

7. The motor assembly of claim 1, further comprising a water jacket in contact with a lower portion of the drive shaft.

8. The motor assembly of claim 7 wherein said seal housing is positioned about a portion of said water jacket.

9. A susceptor assembly comprising:

the motor assembly of claim 1; and

a base in communication with a top of the drive shaft.

10. The base assembly of claim 9, further comprising a torque plate that forms an interface between the drive shaft and the base.

11. The base assembly of claim 10, further comprising a reflective plate between the torque plate and the base.

12. The susceptor assembly of claim 9, wherein the susceptor includes a plurality of grooves in a top surface of the susceptor.

13. The base assembly of claim 12, further comprising a plurality of channels extending from the cavity of the drive shaft to the recess in the base.

14. The base assembly of claim 13, further comprising a valve in fluid communication with the channel.

15. An electric motor assembly comprising:

a motor housing having a top and a bottom;

a drive shaft extending a distance from the top of the motor housing, the drive shaft having a cavity therein with at least one channel forming a fluid connection to the cavity;

a first motor within said motor housing to rotate said drive shaft within said motor housing about a central axis;

a sealed housing within the motor housing, the sealed housing having a gas space therein and located around a portion of the drive shaft, the gas space being in fluid communication with the cavity in the drive shaft through the at least one channel; and

a water jacket contacting a lower portion of the driving shaft partially surrounded by the sealing housing,

wherein the sealed housing is in fluid communication with a vacuum source.

16. A susceptor assembly comprising:

the motor assembly of claim 15; and

a torque plate positioned adjacent to the drive shaft;

a reflective plate adjacent to the torque plate; and

a base adjacent to the reflection plate, the base including a plurality of grooves in a top surface of the base,

wherein the base includes a number of channels extending from the cavity in the drive shaft to the recess in the base.

17. A processing chamber, comprising:

at least one gas distribution assembly within the processing chamber;

a susceptor assembly positioned below at least one gas distribution assembly, the susceptor assembly comprising a top surface, a bottom surface, and at least one recess in the top surface for supporting a wafer; and

a motor assembly, comprising:

a motor housing having a top and a bottom;

a second motor adjacent to the bottom of the motor housing, the second motor in communication with at least one guide rail within the motor housing to move the first motor and the drive shaft along the central axis to move the base assembly toward and away from the at least one gas distribution assembly;

at least one channel extending between a bottom surface of the at least one recess in the base assembly and the cavity in the drive shaft; and

a sealed housing within the motor housing, the sealed housing positioned around a portion of the drive shaft,

wherein the drive shaft includes at least one channel forming a fluid connection between the cavity of the drive shaft and the seal housing,

wherein the sealed housing is in fluid communication with a vacuum source.