JP4503714B2 - High temperature resistance heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating mechanism for a process chamber, and more particularly to a heating mechanism for a chemical vapor deposition chamber.
[0002]
[Prior art]
Chemical vapor deposition (CVD) is a common process for depositing various films on a substrate and is widely used in the manufacture of semiconductor integrated circuits. In the CVD process, a chemical gas containing atoms necessary for the final film is mixed and reacted in a deposition chamber. Elements and molecules accumulate and accumulate on the substrate surface to form a film. The substrate on which the film is to be deposited is usually mounted on a susceptor. The susceptor can be composed of various materials depending on the type of CVD process. It is desirable for the susceptor to have good thermal conductivity and high resistance to thermal deformation. For example, aluminum is a widely used susceptor material with good thermal conductivity, but it is too brittle to withstand high temperatures. Thus, aluminum can only be used in a low temperature CVD process. In high temperature CVD processes, susceptors made of glass or graphite coated with aluminum nitride (AlN) are widely used.
[0003]
[Problems to be solved by the invention]
Two basic heating schemes are used in CVD systems that are distinguished based on the method of heating the susceptor. The resistance heating method uses a resistance heating element to heat the susceptor and cause a more localized reaction on the wafer. The lamp heating scheme uses a radiant heating lamp that heats the susceptor along with other components in the chamber. This scheme produces a reaction throughout the chamber.
[0004]
In a lamp heating system, the substrate is supported on a susceptor, and heat is transferred to the substrate through the susceptor by a lamp placed behind a heat-resistant protective glass in the chamber. In a resistance heating system, the resistance heating element is placed in the wafer holder. In the lamp heating system, heat-resistant glass, usually made of quartz, absorbs heat from the lamp and becomes hot. Thus, chemical reactions occur on the surface of the glass, thereby creating a coating on the glass, reducing the effectiveness of the lamp heater and corroding the glass after repeated processing.
[0005]
In addition, a thermocouple is connected to the substrate holder to measure the thermal variation of the holder during processing. In a lamp heating system, this thermocouple must be in the chamber. In a resistive heating system, the thermocouple can be placed in a controlled environment within the system that holds the heating element. This prevents the thermocouple from being exposed to the elements in the processing chamber, thereby increasing the lifetime of the thermocouple and improving its accuracy.
[0006]
Still further, maintainability of the lamp heated CVD chamber is more important than in the case of resistance heating systems. For example, the installation and calibration of susceptors and wafer lift mechanisms is time consuming and problematic.
[0007]
A typical CVD process useful for various semiconductor applications is the dichlorosilane (DCS) tungsten silicide process. Due to the temperature at which the DCS process takes place, conventional resistive heating systems are usually not suitable for that process. This is because conventional resistance heating systems cannot maintain the required process temperature range (500 ° C. to 600 ° C.). As a result, this process is performed, for example, in a halogen lamp heated CVD chamber. However, it would be useful if there was a resistive heating chamber where a DCS process could occur.
[0008]
In the DCS tungsten silicide process, the tungsten silicide film is WF. ₆ , DCS, and SiH _Four Formed by the reaction of As with other CVD processes, after processing a series of wafers (typically 25), the chamber is cleaned to remove reaction products deposited on the walls of the reaction chamber and other components within the chamber. During the cleaning process, the wafer holder is left in the CVD chamber.
[0009]
Two different types of cleaning processes are commonly utilized: chemical cleaning and plasma cleaning. Plasma cleaning is NF _Three And generating a plasma using RF energy. As a result, plasma cleaning is more localized and more difficult to control, resulting in uneven deposition cleaning. If the plasma cleaning process is performed in the temperature range of 500 ° C. to 600 ° C., the susceptor will be severely damaged and a large amount of particulate matter will be generated from other parts of the system. In addition, plasma cleaning is local and inferior in uniformity. Chemical cleaning is more uniform, but the stress on the chamber components is greater.
[0010]
One type of chemical cleaning involves ClF in the processing chamber. _Three And generating a heat-dependent reaction that becomes more intense at higher temperatures. Chemical cleaning can damage the susceptor if not properly controlled. Chlorine tetrafluoride (ClF) at a temperature of 300 ° C to 600 ° C _Three ) Is undesirable because it can cause both mechanical stress and chemical corrosion to the susceptor. For example, when a glass carbon susceptor is used, chemical cleaning must be performed at a temperature of 200 ° C. This chemical cleaning requires a step of cooling the processing chamber from a DCS tungsten silicide processing temperature of 500-600 ° C., thus reducing the processing capacity of the chamber.
[0011]
To date, it has been preferred to use a radiation heated CVD system for processes such as the DCS tungsten silicide process. Such a system is more resistant to thermal stresses and to the chemical cleaning process utilized in the process. However, it is desirable to provide a resistance heated CVD chamber that can be used in a CVD process. This is a DCS process that needs to demonstrate all the advantages of a cold wall resistive heating system.
[0012]
[Means for Solving the Problems]
In general terms, the present invention includes a resistive heating system for a process apparatus such as a chemical vapor deposition chamber. The system includes a resistance heating substrate holder having a support surface and a support shaft, the holder being composed of a first material. The support surface includes a resistance heating element. The support shaft has a predetermined length and also allows a thermocouple to engage the support surface and a through hole that allows the conductor to be coupled to a resistance heating element in the support surface have.
[0013]
A metal mounting structure is coupled to the support shaft and secured to the process equipment to create a sealed environment within the holder and mounting structure to protect the electrical leads and thermocouple from the processing environment.
[0014]
In one embodiment, a coupling structure is provided to secure the support shaft to the mounting structure. This coupling structure is optimized to provide rigid support with minimal thermal stress during coupling. In this respect, the coupling structure may include a support member made of the same material as the substrate holder, and reduce thermal stress induced by heating the substrate holder and the support member.
[0015]
The length of the shaft can be adjusted based on the materials used for the substrate holder and mounting structure. This allows different materials to be used for the mounting structure and the substrate holder, and these materials can be optimized for the particular process used in the process chamber. The length of the shaft can be adjusted based on the material used and the temperature of the process that the heating system is designed to support. In one embodiment, the holder and shaft are made of aluminum nitride and the mounting structure is made of nickel or a nickel alloy. By adjusting the length of the shaft, the temperature of the process will be higher than the temperature at the point where the shaft and mounting structure are joined, and the temperature at the joint will be optimized for the materials used Can do.
[0016]
In addition, the heater utilizes a control scheme that controls the power output of the resistance heating element based on the thermal resistivity of the heater structure.
[0017]
The invention will be described with respect to particular embodiments. Other objects, features and advantages of the present invention will become apparent with reference to the present specification and drawings.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment of a resistance heating device 10 of the present invention. The resistance heating device 10 includes a resistance heating substrate holder 12 and an attachment structure 14. It will be appreciated that the wafer heating apparatus 10 resides in a sealable processing chamber, such as a chemical vapor deposition (CVD) chamber. The substrate holder 12 has a flat surface 16 on which a substrate made of a semiconductor material can be placed for processing in a CVD chamber (not shown).
[0019]
The resistance heating wafer holder 12 includes a wafer holding part 18 and a support shaft 20. In one embodiment, wafer holder 18 and shaft 20 are made from aluminum nitride. The shaft 20 can be diffusion bonded to the wafer holder 18. The mounting structure 14 is made of a strong metallic material (in some embodiments including nickel 200 (ANSI nickel 200)) and secures the wafer holder 12 to the process chamber.
[0020]
Other materials may be used to manufacture the wafer holder 10 and mounting structure 14 without departing from the spirit and scope of the present invention. In the embodiment described here, a relatively pure (99.97%) compound of aluminum nitride is utilized. Aluminum nitride of this composition of this embodiment has been found to be particularly advantageous in process environments with temperatures in the range of 500-600 ° C. The impurity of the AlN compound is yttrium oxide (Y ₂ O _Three ) Or carbon.
[0021]
A characteristic feature of one embodiment of the present invention is that the support shaft is made of a first material having a different coefficient of thermal expansion from the second material constituting the mounting structure. 20 In combination with the use of This allows the materials used for each part of the device to be selected for optimal performance of the heating device. For example, aluminum nitride has good heat resistance and corrosion resistance, while nickel alloy has great strength and durability. Thus, in one embodiment, the aluminum nitride shaft 20 and the holder 12 having the nickel attachment structure 14 that secures the wafer holder 12 is for use at a process temperature at the surface 16 of the wafer holder 12 of, for example, about 500 ° C. in a DCS process. It is suitably realized.
[0022]
At this temperature, it is problematic to attach the wafer holder 12 directly to the mounting structure 14 by directly coupling the shaft 32 to the holding portion 18. This is because, at temperatures close to 500 ° C., the difference in thermal expansion characteristics of each material generates stress, and this stress weakens the conventional joining technique for joining the materials. Furthermore, due to the nature of the chemical process in the process chamber, repeated erosion by the chemical in the chamber has a corrosive effect on the metal shaft itself as well as its joints, so that the metal mounting structure and the aluminum nitride wafer It becomes difficult to maintain reliable bonding with the holder.
[0023]
Accordingly, in the first embodiment of the present invention, the first characteristic feature of the present invention is that the temperature T at the surface 16 of the wafer holder 12 is ₁ And the second temperature T where the shaft 20 is joined to the mounting structure 14. ₂ A specific length L that gives a certain temperature drop between ₁ The shaft 20 is manufactured. T ₂ And T ₁ The difference or decrease between is the material used for each part and the process temperature T at the surface 16. ₁ And thus the required length L of the shaft 20 ₁ Is given.
[0024]
In another embodiment shown in FIG. 10, the shaft 20a has a length (L) equal to the total distance between the wafer holder 12 and the mounting hardware 100a in the process chamber. ₂ ).
[0025]
Another feature unique to the present invention is that an internal conduit is provided to allow the thermocouple and conductor leads to be isolated from chemical reactions within the chamber and placed in a controlled environment within the heating device. In some systems, exposed terminals utilized in metal chemical vapor deposition chambers can eventually be shorted by metal deposition during the chemical process. Therefore, it is desirable to provide the terminal inside the board mounting structure. In the system of the present invention, the process occurring in the vacuum does not interact with the thermocouple or conductor inside the shaft. The control environment inside the shaft can be isolated from the vacuum process chamber and maintained at atmospheric conditions.
[0026]
The resistance heating wafer holder 12 and the shaft 20 are shown in more detail in FIGS. 2 (a) to 2 (c). As shown in the drawing, the shaft 20 has a first conduit 22 in which a thermocouple can be installed, and a conductor to a resistance heating element arranged in the substrate holder 12. 2 and third conduits 23, 24. Through holes 25, 26, 27, 28 are provided on the surface 16 so that the substrate lift fingers can move the substrate up and down on the surface 16 of the resistance heating structure 10 through the wafer holder 12. The thermocouple insertion region 30 is provided at the center of the surface 16 of the resistance substrate holder 12.
[0027]
For coupling with the support shaft 20 A first embodiment of the mounting structure 14 using the first coupling structure 50 is shown in FIGS. The coupling structure 50 is important because it must support the entire wafer holder structure 12 and shaft 20. The mounting structure 14 is Having an end portion 36 for slidably receiving the bellows member 34; A shaft 32 is included. The bellows member 34 includes a first surface 35 that engages the shaft 20 of the substrate holder 12. The second surface 37 faces the inner region 38 of the shaft 32. The interior region 38 of the shaft 32 provides a controlled environment that is maintained at approximately atmospheric conditions during the chemical vapor deposition process when the bellows member 34 is secured to the shaft 32. A support disk 40 having a diameter substantially equal to the diameter of the shaft 20 is in contact with the lower surface 37 of the bellows member 34. The bellows member 34 is fixed to the shaft 32 by E-beam welding.
[0028]
The bellows member 34 is provided to allow a certain degree of flexibility between the shaft 28 and the nickel shaft 32. The bellows member 34 may be made of nickel, but is typically thinner (about 2 mils thick) than the nickel material that makes up the shaft 32. Since aluminum nitride and nickel have different coefficients of thermal expansion, when heated, deflection allows expansion at different rates between the shafts while maintaining a good seal. This thermal expansion is an important issue that must be overcome in order to be able to couple the shaft 20 to the shaft 32. E-beam welding may be used to attach the bellows member 34 to the shaft 32, but brazing is utilized to attach the aluminum nitride shaft 20 to the bellows member 34. The first brazing is performed at the interface between the shaft 20 and the surface 35 of the bellows member 34. The second brazing is performed at the interface 44 between the disc member 40 and the surface 37 of the bellows 34. The disk member 40 is a counter-stress member made of aluminum nitride, and is provided for thermal expansion matching between the shaft 20 and the bellows member 34. The bellows member allows for the expansion of the shaft 20 and the shaft member 32. Without the deflection of the bellows member, the brazing will not be strong enough to resist breakage due to the stress generated during heating and the differential thermal expansion between the aluminum nitride shaft 20 and shaft 32. In general, nickel expands more than aluminum nitride. As a result, the vertical tensile stress (F ₁ ) Will exist. Since the ring 40 is aluminum nitride, there is little expansion, and this force is divided in half. Therefore, the tensile stress becomes compression and the strain becomes more uniform. Similarly, in FIG. ₂ The stress along the direction indicated by is also halved by the presence of the ring 40.
[0029]
The brazing utilized is a silver / copper material with a small amount of titanium, which is chlorine tetrafluoride (ClF) utilized in high temperature cleaning processes. _Three ) Can not withstand erosion. By changing the length of the shaft to reduce the temperature of the joint, erosion can be minimized. Further, the exposed wax is plated with a thickness of about 0.001 inch using nickel 200 to protect and prevent wax contamination from chemical erosion.
[0030]
As can be understood by those skilled in the art, the length L in FIG. ₁ Is selected based on the temperature required at the joint between the shaft 20 and the shaft 32. L ₁ Can vary based on the use of materials utilized for the structure 10 and the nature of the process in which the structure 10 is to be manipulated.
[0031]
4 to 8 show a second embodiment of the present invention. Specifically, the shaft 20 is attached to the mounting structure 14. ₁ Coupling structure 50 to be fixed to ₁ Is shown. In this type of coupling structure, the mounting structure 14 ₁ Has a clamp that provides another support for coupling. This mounting structure 14 ₁ Is essentially similar to the mounting structure 14 except that a clamp coupling 52 is provided at the end of the mounting structure 14. FIG. 4 is a plan view of the second embodiment of the present invention, and FIG. 5 is a view taken along line 5-5 of FIG. As shown, the mounting structure 14 ₁ Has a first end 51 that includes a clamp 52 formed by an annular member 54 and a clamp member 56. Screw holes 58 and 59 are provided in the clamp member 56 and the annular member 54, and the shaft 20 is fixed to a predetermined position in the mounting structure 14 by using bolts (not shown).
[0032]
Mounting structure 14 ₁ In order to create a safe environment isolated from the process chamber in the inner portion 38, a nickel 200 L-shaped ring 60 having a thickness of 2 mils is connected to the shaft 20 in the inner region 38 of the second embodiment of the present invention. It is arranged between the aluminum nitride support ring 40. Brazing is used at the interface 62 between the shaft 20 and the L-shaped ring 60, and a second brazing is used at the interface 64 between the ring 40 and the lower surface of the L-shaped ring 60. Inner ring 65 and mounting structure 14 ₁ No lip 15 ₁ At point 66 at the interface with E, E-beam welding or laser beam welding is utilized. Welding the shaft 32 ₁ Provides a vacuum seal to the interior region 38 of the Thereby, the function of providing a vacuum seal to the inner portion 38 and the function of supporting the resistance heating substrate holder 12 are separated.
[0033]
Thus, the mounting structure and the interior of the shaft 32 provide a controlled environment that is isolated from the process chamber vacuum. This allows the thermocouple and the heating element conductor to be maintained at atmospheric pressure so that they are isolated from the effects of the process in the chamber, increase their lifetime, and increase the overall strength of the heating structure.
[0034]
FIG. 6 shows a coupling structure 50. ₁ FIG. 2 shows a side cross-sectional view of resistance heating structure 10 including a second configuration of FIG. 2 and electrical conduits 108, 110 coupling resistance heating elements in wafer holder 12 to the apparatus. The same reference numbers are used for parts similar to the previous figures. As shown in FIG. 6, the mounting structure 14 is fixed by providing the chamber mount 100 in the chamber. The chamber mount is typically coupled to a chemical vapor deposition chamber or other processing chamber (not shown). The chamber mount includes a fluid conduit 102. A fluid conduit may be provided for water cooling of the heating structure 10. Mounting structure 14 or 14 ₁ A bore 103 is provided in the chamber mount 100. The flange 105 of the chamber mount 100 is installed on the chamber wall and serves to support the heating structure. Electrical connectors 107, 109 are provided in the chamber mount 100 and the conduit 104 ₁ , 106 ₁ Is bound to. Electrical conduit 104 in mounting structure 14 ₁ , 106 ₁ Are located in an internal region 38 within the control environment. Corresponding conduit 104 in shaft 20 ₂ , 106 ₂ The shaft 20 and the shaft 32 ₁ Conduit 104 by electrical connectors 112, 114 located at the interface with ₁ , 106 ₁ Combined with Lip 15 enabling seating of the support ring 40 ₁ An exhaust port 118 is provided at the interface between the shaft 20 and the shaft 20 so that residual gas can escape.
[0035]
FIG. 7 shows a cross-section similar to that of the heating structure shown in FIG. 6, but showing a thermocouple 120 located at a predetermined location within the controlled environment within region 38. As illustrated, a connector 122 for the thermocouple 120 is provided in the chamber mount 100. A bore 140 in mount 100 allows connection of thermocouple 120 to the CVD system. As described above, the thermocouple is maintained at atmospheric pressure within the bore.
[0036]
FIG. 7 illustrates another feature unique to the present invention that includes increasing the accuracy of the temperature measured by the thermocouple 120 at the intersection of the thermocouple and the substrate holder. In the region 22 that forms the intersection of the shaft 20 and the wafer holder 18, the aluminum nitride thickness T ₁ Is the thickness T of the wafer holding region 18 across the width (diameter) of the shaft 20 ₂ Bigger than. This increase in thickness compensates for heat loss in the center of the wafer holding area. The use of a thermocouple in the center of the wafer holding area itself increases the heat loss in the area due to the need to provide a conduit in the aluminum nitride below the wafer holding surface. In addition, since the heat loss of the object in the atmosphere is larger than the object in the vacuum, the heat loss increases due to the fact that a thermocouple is provided in the atmosphere. If the thickness of the aluminum nitride in the region 22 is the same as the thickness in the region, the heat loss in this region will be greater than the heat loss in the entire remainder of the wafer holding region 18. Accordingly, the thickness of aluminum nitride in this region is increased to reduce heat loss.
[0037]
Another solution to increasing the thickness of this region is to use the same thickness T of the wafer holding region. ₂ Is to increase the density of the heating elements in region 22. Such a solution may make the formation of this structure more complex and will increase the thermal stress in region 22.
[0038]
Another feature unique to the present invention is the thickness T of the wafer holding region 18. ₂ Is selected to control the thermal ramp rate of the heating structure of the present invention. Conventionally, the thickness of the resistance heater is on the order of 0.7 inches. As is generally understood, the heater ramp rate becomes slower as the thickness increases. However, in some embodiments of the invention, the thickness T ₂ Is on the order of about 0.5 inches. In this way, a considerably short cooling time can be realized for the heater.
[0039]
The heater ramping control in the heating structure of the present invention also achieves precise control over the process occurring in the CVD chamber, and also avoids heater thermal cracking and prevents excessive heater downtime. Because it is particularly important. If the rate of temperature change is too fast, cracking will occur, but if the rate of change is too low, the overall throughput of the CVD system will be reduced.
[0040]
Accordingly, another feature unique to the present invention utilizes a scheme for controlling the heating and cooling rates of the heater structure of the present invention. Since the thermal expansion coefficient of molybdenum is equal to the thermal expansion coefficient of aluminum nitride, in this system, the heating element is made of molybdenum. However, the unique features of the heater of the present invention can be applied to resistance heating elements made of various types of materials.
[0041]
In a ceramic heating system as described herein, the resistivity of the heating element increases with temperature. This complicates the control of the temperature ramp rate of the heater structure. The change in resistivity may triple as the temperature increases from room temperature to 600 ° C. Thus, the change in resistivity may result in a significant impact on the heater power output.
[0042]
In general, the heater element is controlled by either current adjustment or voltage adjustment. The power output of the heater in voltage control mode is
Power = (Voltage) ² /Resistivity
In the current control mode,
Power = (current) ² /Resistivity
It is. This means that at low voltage and current inputs, the heater power output decreases with increasing temperature and resistivity. The resistance heating element of the prior art uses an error compensation method that takes into account the error between the actual temperature input and the set temperature voltage input, but any variation in the resistivity of the heater material caused by the temperature rise is compensated. It wasn't. For example, a so-called PID (proportional integral derivative) error correction algorithm is generally used.
[0043]
In the heater system of the present invention, a heater control method is used in which the voltage input is changed by adjusting the voltage input so as to compensate for the change in resistivity of the heater element material as the heater temperature rises. In general, this scheme implements the following equation for control of the input voltage. That is, in voltage mode control,
True voltage input = (calculated voltage input) x f1 (t)
And in current mode control
True current input = (calculated current input) x f2 (t)
It is. Here, the calculated voltage input is derived from an arbitrary control algorithm of the heater element without considering the influence of the resistivity change, and f1 and f2 are arbitrary values that justify the variation of the resistivity due to the temperature change. Is a function of temperature.
[0044]
Of course, the functions f1, f2 will vary depending on the material used for the heater element, and these functions can be varied depending on the accuracy desired to be realized. These functions can be implemented in a circuit that directly controls voltage and current regulation, or in software that is ported to a special processor that controls voltage and current regulation. There are many different control processor implementations and software implementations available to implement this function of the heater of the present invention.
[0045]
8 and 9 show the clamp member 50. ₂ The cross section of the other 3rd form is shown. In this embodiment, the clamp member 50 ₂ Comprises an independently formed arcuate portion 124 having opposing clamp arms 121. Two through holes 126 and 127 are provided to fix the clamp arm so as to face the arcuate clamp member 124, and corresponding through holes 128 (shown only in FIG. 8 with respect to the hole 126) are formed in the clamp arm 121. Is provided. The structure shown in FIG. 8 is determined to be very robust and allows for fewer fixtures for the configuration shown in FIGS.
[0046]
FIG. 10 shows a fourth embodiment 10 of the present invention. _Four Is shown. In this embodiment, the aluminum nitride shaft 20a has a length equal to the total distance between the wafer holder 18a and the mounting hardware 100a in the chamber. As shown in FIG. 10, the shaft 20a made of a ceramic material such as AlN has a first end coupled to the holding portion 18a and a second bottom end coupled to the chamber mount hardware 100a. is doing.
[0047]
The shaft 20 a includes an internal chamber 138. This allows for the thermocouple 120a and electrical leads (only 106a shown in FIG. 10) to be placed in a controlled environment within the chamber 138, isolated from the vacuum environment inside the process chamber and maintained at atmospheric conditions. . The length of the shaft is now L ₂ This eliminates the problem of coupling the AlN portion of the shaft 20a to an independent metal shaft and coupling the metal shaft to the coupling hardware. With respect to conductive electrodes and thermocouples, only one tightening point—in the coupling structure 100a—must be handled to ensure that the isolated ambient environment 140 is maintained within the shaft 20a.
[0048]
In the coupling structure 100a, the shaft 20a is fixed to the base member 136 by the through hole 125 and the flange clamp 130 of the flange portion 135 of the shaft 20a, which are coupled by a hexagon nut. Since the shaft includes the entire thermocouple and conductive electrode, only one clamping point--at the base of the shaft--requires a separate metal shaft portion (eg, 14) and ceramic shaft (eg, shaft 20). There is no need for a separate fastener at the joint between the two. The conductor 106a is connected to the process chamber via a connector 103a via a spring-type fastener 134. Conductor 106 ₂ Is fixed inside the ceramic insulator 111. One end of the insulator 111 is fixed to the recess 133 of the holding region 18a, and the other end is fixed by a spring-type fastener 134. Fastener 134 includes a pedestal 135 that engages spring 136, which is itself attached to shaft 137. The pedestal 135 pushes the insulator 111 into engagement with the recess 133. The shaft 137 is held in the counter bore 139 of the mount block 140 and is fixed to the base member 136.
[0049]
Finally, it is emphasized that the diameter of the first end 142 of the shaft 20a is greater than the diameter of the second end 144. This allows for a larger coupling area between the shaft 20a and the holding region 18a. Further, the thickness T of the holding portion 18a _Three And T _Four The difference (X) between is the T of the previous form ₁ And T ₂ Not as big as the difference. Center thickness T _Three And peripheral thickness T _Four There is a difference in thickness between them and the heat fluctuation due to the pressure difference between the region on the shaft 20a and the atmosphere. _Four The manufacturability is improved.
[0050]
Various features and advantages of the invention will be apparent to those skilled in the art. All such features and advantages of the invention are intended to be within the scope of the invention as defined by the application and the claims.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a resistance heating structure according to the present invention.
2A is a first side view of a resistance heating wafer holder according to the present invention, FIG. 2B is a plan view of a resistance heating wafer holder according to the present invention, and FIG. It is a 2nd side view of the resistance heating wafer holder which concerns on this invention.
FIG. 3 is an enlarged cross-sectional view of a first mechanism for coupling the mounting structure to a resistance heating wafer holder.
FIG. 4 is a plan view of a second embodiment of a mounting structure according to the present invention.
5 is a cross-sectional view of the mounting structure shown in FIG. 4, showing a method of bonding to the resistance heating wafer holder of the second embodiment of the present invention using the mounting structure.
FIG. 6 is a cross-sectional view of a resistance heating structure showing a conduit for a conductive lead coupled to a resistance heating element in a wafer holder.
FIG. 7 is a second cross-sectional view of a resistance heating structure according to the present invention, showing a conduit and a thermocouple coupled to a resistance heating element according to the present invention.
FIG. 8 is an enlarged cross-sectional view of a third embodiment of a mounting structure for engaging with a resistance heating wafer holder according to the present invention.
9 is a cross-sectional view taken along line 9-9 of FIG.
FIG. 10 is a cross-sectional view of a fourth embodiment of a resistance heating structure using a full length ceramic shaft according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Resistance heating apparatus, 12 ... Resistance heating wafer holder, 14 ... Mounting structure, 18 ... Wafer holding part, 20 ... Support shaft, 32 ... Support shaft.

Claims (15)

A resistance heating device for a chemical vapor deposition chamber,
A first material having a first coefficient of thermal expansion, comprising a resistance heating element, a wafer support region [18, 18a], and a support shaft [20, 20a] supporting the wafer support region; A substrate holding member [12, 12a], wherein the support shaft has a length defined by a first end coupled to the wafer support region and a base end;
An attachment structure [14] composed of a second material having a second coefficient of thermal expansion and coupled to the support shaft at a coupling location;
The support shaft and mounting structure includes an inner region [38] that contains at least a conductor coupled to the resistance heating element;
The length of the support shaft, the so that a lower than the process temperature at the temperature said wafer support area at the coupling point, is determined based on the process temperature,
The support shaft is coupled to the mounting structure by a bellows member [34] and a reverse stress member [40],
The bellows member is made of the second material, and has a first surface [35] that engages with the support shaft, a second surface [37] that faces the first surface, and the mounting structure. An end engaging the end [36],
The said reverse stress member consists of said 1st material, The resistance heating apparatus engaged with the said 2nd surface so that the said support shaft may be opposed on both sides of the said bellows member.   The apparatus of claim 1, wherein the first material is an aluminum nitride compound.   The apparatus of claim 2, wherein the first material is AlN having a purity of at least 99%. The apparatus of claim 1 , further comprising a thermocouple disposed in the interior region .   The apparatus of claim 1, wherein the process temperature is higher than 450 ° C. The apparatus according to claim 5 , wherein the temperature at the coupling point is lower than 300 ° C. Means for controlling the power output of the resistance heating element, based on the thermal resistivity and temperature of the resistance heating element so that the power output of the resistance heating element is constant. current input or further comprising apparatus of claim 1, a control means for controlling a voltage input. The apparatus according to claim 7 , wherein the control unit controls current input or voltage input to the resistance heating element based on a change in thermal resistivity accompanying an increase in temperature of the resistance heating element. It said support shaft includes at least one conduit [108, 110] to comprise that apparatus of claim 1 for supporting the conductor that is isolated from the chemical vapor deposition chamber. The apparatus of claim 9 , wherein the support shaft further comprises a thermocouple conduit [120, 120a].   The apparatus of claim 1, wherein the second material is nickel or a nickel alloy. The support shaft [20, 20a] is brazed to the first surface of the bellows member [34] and is aligned with the reverse stress member [40], the reverse stress member [40] members [34] the apparatus of claim 1 wherein the brazed to the second surface of the. A heater [10] for a chemical vapor deposition system comprising:
A first part [12];
A second part [14];
A coupling structure coupling the first part and the second part via a stress support ring [40] and a seal [60],
The first part is
A substrate holder [18];
A resistance heating element disposed inside the substrate holder;
At least a conductor coupled to the resistance heating element;
A support bonded to the substrate holding portion, made of a first material having the same material as the substrate holding portion and having a first coefficient of thermal expansion, and having an inner region [38] for accommodating the conductor. An arm [20],
The second part [14]
A mounting structure [14 ₁ ] composed of a second material having an end [36, 52, 50 ₂ ] capable of receiving the support arm and having a second coefficient of thermal expansion ;
Said internal region [38],
The seal [60] is made of the second material, and includes a first surface that engages the support arm [20], a second surface that faces the first surface, and the mounting structure [14. ₁ ] having an end portion engaged with the end portion [36, 52, 50 ₂ ],
The stress support ring [40] is made of the first material and is engaged with the second surface so as to face the support arm [20] with the seal [60] interposed therebetween. The heater according to claim 13 , wherein a material of the substrate holding portion is an aluminum nitride compound. The heater according to claim 14 , wherein a material of the substrate holding part is AlN having a purity of at least 99%.

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