Page 1 of 16
`
`SAMSUNG ET AL. EXHIBIT 1080
`Samsung et al. v. Elm 3DS Innovations, LLC
`IPR2016-00387
`
`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 1 of 8
`
`US 6,204,174 B1
`
`Page 2 of 16
`
`Page 2 of 16
`
`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 2 of 8
`
`US 6,204,174 B1
`
`36
`
`Page 3 of 16
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`Page 3 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 3 of 8
`
`US 6,204,174 B1
`
`RF
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`Power Supply
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`Page 4 of 16
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`Page 4 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 4 of 8
`
`US 6,204,174 B1
`
`FIG.4
`
`Page 5 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 5 of 8
`
`US 6,204,174 B1
`
`Processorselector
`
`Chamber Selection
`Temperature
`Process Gas Flow
`
`Pressure
`Plasma Power
`
`148
`
`P
`
`100933
`
`150
`
`146
`
`/-
`
`154
`
`Chamber Manager
`
`Chamber Manager
`
`156
`
`Chamber Manager for CVD/Sputtering Chamber
`
`152
`
`160
`
`162
`
`164
`
`166
`
`168
`
`Substrate
`Positioning
`
`Process Gas
`Control
`
`Pressure
`Control
`
`Heater
`Control
`
`Plasma
`Control
`
`Establish Process Parameters
`
`Establish Deposition Rate by
`Selecting Argon/Ethylene Mixture
`
`
`
`
`
`178
`
` 180
`
`182
`
`184
`
`
`
`Introduce Process Gas Including Argon/Ethylene Mixture
`
`Maintain Process Conditions Suitable
`for Depositing Tungsten Layer
`
`FIG. 6
`
`Page 6 of 16
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`Page 6 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 6 of 8
`
`US 6,204,174 B1
`
`
`
`Page 7 of 16
`
`
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`
`
`Page 7 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 7 of 8
`
`US 6,204,174 B1
`
`190
`
`0
`
`2000
`4000
`6000
`8000
`Ethylene (parts per billion of process gas)
`
`10,000
`
`FIG. 9
`
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`9300
`8800
`8300
`
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`Page 8 of 16
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`Page 8 of 16
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`

`

`U.S. Patent
`
`Mar. 20, 2001
`
`Sheet 8 of 8
`
`US 6,204,174 B1
`
`Deposition
`Gas Panel
`
`.
`
`230
`
`230a
`
`32
`
`A
`
`210
`
`212
`
`214
`
`216
`
`218
`
`220
`
`222
`
`FIG. 11
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`Page 9 of 16
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`Page 9 of 16
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`

`

`US 6,204,174 B1
`
`1
`METHOD FOR HIGH RATE DEPOSITION
`OF TUNGSTEN
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to the fabrication of inte-
`grated circuits. More particularly, the invention provides a
`technique, including a method and apparatus, for improving
`the deposition rate of refractory metal layers.
`Deposition of refractory metals, such as tungsten, over a
`semiconductor substrate is a common step in the formation
`of some integrated circuit (IC) structures. For example,
`tungsten is commonly used to provide electrical contact to
`portions of a semiconductor substrate. These electrical con-
`tacts are usually provided through openings in an insulation
`layer, such as a silicon dioxide layer, formed over the
`substrate. One method used to form such contacts includes
`
`the chemical vapor deposition (CVD) of tungsten to fill the
`opening after an initial layer of titanium nitride has been
`deposited in the opening. As another example, tungsten is
`sometimes used to form metal lines over a semiconductor
`substrate.
`
`One CVD technique that has been employed to deposit
`tungsten films in the semiconductor industry uses tungsten
`hexafluoride (WF6) and a hydrogen reducing agent, e.g., H2,
`as precursor gases. This technique includes two main steps:
`nucleation and bulk deposition. The nucleation step grows a
`thin layer of tungsten which acts as a growth site for
`subsequent film. In addition to WF6 and H2, the process gas
`used in the nucleation step of this technique includes silane
`(SiH4), and may also include nitrogen (N2) and argon. A
`bulk deposition step then is used to form the tungsten film.
`The bulk deposition gas is a mixture containing WF6, H2,
`N2, and Ar.
`Advances in integrated circuit technology have lead to a
`scaling down of device dimensions and an increase in chip
`size and complexity. This has necessitated improved meth-
`ods for deposition of refractory metals, particularly tungsten
`which has led to a constant endeavor to decrease the quantity
`of impurities, such as ethylene, deposited in the refractory
`metal layers. The aforementioned impurities may have del-
`eterious effects on the refractory metal layer, depending
`upon the nature of the impurity and the quantity present
`therein. Over the past ten years, impurity control has been
`successful in substantially reducing impurities attributable
`to the ambient environment in which refractory metal layers
`are formed so that greater than 80% of all impurities now
`present are a direct result of the process. One such source is
`the contaminants present in the process gases employed to
`form refractory metal layers. As a result, many process gases
`are produced in purified form so that there is less than ten,
`10, parts of contaminants for every one billion, 1,000,000,
`000 parts of process gas. Such purification greatly increases
`the cost of the process gas and,
`therefore,
`the cost of
`depositing a refractory metal layer.
`What is needed, therefore, is an improved method for
`depositing refractory metal layers that lowers the cost of
`producing the same.
`SUMMARY OF THE INVENTION
`
`The present invention provides a method and apparatus
`for controlling a deposition rate of a refractory metal layer,
`such a tungsten, on a silicon substrate, as a function of an
`amount of contaminants present
`in a process gas. The
`present
`invention is based upon the discovery that
`the
`presence of ethylene, C2H4, in a process gas has an effect on
`the deposition rate of a tungsten layer.
`
`2
`The method of the present invention includes placing a
`substrate in a deposition zone, of a semiconductor process
`chamber, flowing, into the deposition zone, a process gas
`including a refractory metal source, an inert carrier gas, and
`a hydrocarbon. Typically,
`the refractory metal source is
`tungsten hexafluoride, WF6, the inert gas is argon, Ar, and
`the hydrocarbon is ethylene, C2H4. The ethylene may be
`premixed with either the argon gas or the tungsten hexafluo-
`ride source to form a homogenous mixture. However, it is
`also possible to mix the ethylene with either the argon gas
`or the tungsten hexafluoride source, in situ, anterior to the
`process chamber.
`
`In an exemplary embodiment of the method in accordance
`with the present invention, a substrate having an anisotropic
`surface is placed in a deposition zone of a substrate process
`chamber. The flow rate of the WF6 gas is between 60 and
`200 sccm, with 95 sccm being preferred. The flow rate of the
`Ar gas is between 1,000 and 6,000 sccm, depending upon
`the chamber temperature. Were the ethylene premixed with
`the argon gas or
`the tungsten hexafluoride source,
`the
`minimum quantity of ethylene present would be no less than
`100 parts for every 1,000,000,000 parts of the process gas.
`The maximum quantity of ethylene present would be no
`greater than 10,000 parts for every 1,000,000,000 parts of
`the process gas. Were the ethylene mixed, in situ with either
`the argon gas or
`the tungsten hexafluoride source,
`the
`mixture rate would be established so that the aforementioned
`
`quantities are obtained in the process chamber.
`
`These and other embodiments of the present invention, as
`well as its advantages and features are described in more
`detail
`in conjunction with the text below and attached
`figures.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of a chemical vapor depo-
`sition (CVD) apparatus according to the present invention;
`FIG. 2 is an exploded perspective view of a lid employed
`on the CVD apparatus shown in FIG. 1;
`
`FIG. 3 is a cross-sectional view of the chemical vapor
`deposition apparatus shown above in FIG. 1;
`
`FIG. 4 is a simplified diagram of system monitor and a
`multi-chamber system employing one or more of the CVD
`apparatus shown above in FIG. 1; and
`
`FIG. 5 is an illustrative block diagram of the hierarchical
`control structure of the system control software employed to
`control the operation of the CVD apparatus shown in FIG.
`1;
`
`FIG. 6 is a flowchart illustrating the steps of a preferred
`embodiment of the present invention;
`
`FIG. 7 is a cross-sectional view of a portion of an
`integrated circuit in which a refractory metal layer is depos-
`ited in accordance with the present invention;
`
`FIG. 8 is a cross-sectional view of the integrated circuit
`shown in FIG. 7 with a refractory metal layer disposed
`thereon in accordance with the present invention;
`
`FIG. 9 is a graph depicting the thickness of the refractory
`metal layer shown in 8 versus the quantity of hydrocarbons
`in the process gas, for a fixed deposition time;
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`FIG. 10 is a schematic view showing an hydrocarbon
`delivery system in accord with the present invention; and
`
`65
`
`FIG. 11 is an alternate embodiment of the hydrocarbon
`delivery system in accord with the present invention.
`
`Page 10 of 16
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`Page 10 of 16
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`

`

`US 6,204,174 B1
`
`3
`DETAILED DESCRIPTION OF THE SPECIFIC
`EMBODIMENTS
`
`I. Exemplary CVD System
`Referring to FIG. 1, a suitable chemical vapor deposition
`(CVD) apparatus 26 in which the method of the present
`invention can be carried out
`is shown as including an
`enclosure assembly 28 formed from a process-compatible
`material, such as aluminum or anodized aluminum. The
`enclosure assembly 28 includes a housing 30, defining a
`process chamber 32 with an opening 34, and a vacuum lid
`36. The vacuum lid 36 is pivotally coupled to the housing 30
`via a hinge 38 to selectively cover the opening 34. A handle
`40 is attached to the vacuum lid 36, opposite to the hinge 38.
`The handle 40 facilitates moving the vacuum lid 36 between
`opened and closed positions. In the opened position,
`the
`opening 34 is exposed, allowing access to the process
`chamber 32. In the closed position, the vacuum lid 36 covers
`the opening 34, forming a fluid- tight seal therewith. To that
`end, lid clamps 42 may be employed to resiliently bias the
`vacuum lid 36 against
`the housing 30. The hinge 38,
`however, includes a locking ratchet mechanism 44 to pre-
`vent the vacuum lid 36 from unintentionally moving into the
`closed position.
`A gas distribution assembly 46 is typically attached to the
`vacuum lid 36. The gas distribution assembly 46 delivers
`reactive and carrier gasses into the process chamber 32,
`discussed more fully below. Acover 48 is in superimposition
`with the vacuum lid 36 and adapted to enshroud the gas
`distribution assembly 46. To that end, the cover 48 includes
`a cover portion 50 lying in a plane that extends parallel to a
`plane in which the vacuum lid 36 lies. Aside wall 52 extends
`from the cover portion 50, terminating in a periphery 54. The
`contour of the periphery 54 typically matches the contour of
`the components of the apparatus 26 disposed on the vacuum
`lid 36. For example, the periphery 54 may include recessed
`portions 56 which are positioned to receive one of the lid
`clamps 42 when the cover 45 is seated against the vacuum
`lid 36. To facilitate access to the process chamber 32,
`without compromising the fluid-tight seal between the
`vacuum lid 36 and the housing 30, a slit valve opening 58
`is present in the housing 30, as well as a vacuum lock door
`(not shown). The slit valve opening 58 allows transfer of a
`wafer (not shown) between the process chamber 32 and the
`exterior of the apparatus 26. The aforementioned transfer
`may be achieved by any conventional wafer transfer assem-
`bly (not shown). An example of a conventional robotic wafer
`transfer assembly is described in commonly assigned U.S.
`Pat. No. 4,951,601 to Maydan, the complete disclosure of
`which is incorporated herein by reference.
`Referring to FIG. 2, the vacuum lid 36 includes a base
`plate 60, a gas distribution plate 62 and a sleeve 64. The base
`plate 60 has a centrally disposed aperture 66 and a recessed
`periphery 68, surrounding the aperture 66. The sleeve 64 has
`a shape complementary to the shape of the aperture 66 so as
`to fit therein. Typically, the sleeve 64 includes a cylindrical
`wall 70, which fits into the aperture 66, with a circular flange
`72 extending from one end. The circular flange 72 seats
`against the recessed periphery 68 when the sleeve 64 is
`placed in a final seating position. To maintain fluid-tight
`integrity between the sleeve 64 and the base plate 60 a
`sealing member 74, such as gasket, is positioned between
`the recessed periphery 68 and the circular flange 72. The gas
`distribution plate 62 includes a circular base surface 76 and
`an annular side surface 78 extending from, and transversely
`to,
`the base surface 72,
`terminating in opening 80. A
`plurality of apertures 82 are formed in the circular base
`surface 76. An annular flange 84 extends from the opening
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`80 and transversely to the annular side surface 78 and seats
`against the circular flange 72 of the sleeve 64 when placed
`in a final seating position. In the final seating position, both
`the circular base surface 76 and the annular side surface 78
`
`are encircled by the sleeve 64. A gasket 86 is positioned
`between the circular flange 72 and the annular flange 84 to
`ensure there is a fluid-tight seal
`therebetween. The gas
`distribution assembly 46 includes a lid portion 88 which fits
`over the opening 80 and rests against the annular flange 84.
`A gasket 90 is disposed between the cover portion 88 and the
`annular flange 84 to form a fluid-tight seal therebetween.
`Referring to FIG. 3, the gas distribution assembly 46 is
`attached to the lid portion 88 in any conventional manner,
`e.g., by bolting, brazing and the like. The lid portion 88
`includes a throughway 92 to place the gas distribution
`assembly 46 in fluid communication with the process cham-
`ber 32. A supply 94 of deposition and carrier gases is in fluid
`communication with the gas distribution assembly 46 via a
`mixing manifold 96. Specifically, a plurality of supply lines
`98 are coupled between the supply 94 and the mixing
`manifold 96. The carrier and deposition gases may be
`intermingled in the mixing manifold 96 before flowing into
`the gas distribution assembly 46 via conduit 100. Typically,
`the supply line for each supply of gas includes
`several
`safety shut-off valves (not shown) that may be employed to
`terminate gas flow into the process chamber 32 either
`manually or automatically. Additionally, mass flow control-
`lers (also not shown) may be employed to measure the flow
`of gas through each of the supply lines 98. This structure is
`particularly useful if the supply 94 includes a quantity of
`toxic gases.
`Disposed within the process chamber 32 is a heater/lift
`assembly 102 coupled to a pedestal 104, and a process
`chamber liner 106. The pedestal 104 is positioned between
`the heater/lift assembly 102 and the vacuum lid 36, when the
`vacuum lid 36 is in the closed position. The heater lift
`assembly 102 is operably connected to a motor 108 to be
`controllably moved so as to vary the distance between the
`pedestal 104 and the vacuum lid 36. Information concerning
`the position of the pedestal 104 within the process chamber
`32 is provided by a sensor (not shown). The process chamber
`liner 106 surrounds the pedestal 104 and defines a lower
`portion of an annular flow channel 110, with the upper
`portion of the annular flow channel 110 being defined by the
`vacuum lid 36. The pedestal 104 also includes resistively-
`heated components, such as an embedded single-loop heater
`element (not shown) configured to make two full turns in the
`form of parallel concentric circles. An outer portion (not
`shown) of the heater element runs adjacent to a perimeter of
`the pedestal 104, while an inner portion runs on the path of
`a concentric circle having a smaller radius. The wiring to the
`heater element passes through the stem 112 of the heater/lift
`assembly 102.
`Typically, any or all of the process chamber liner 106, gas
`dispersion plate 62 and various other apparatus 26 hardware
`are made out of material such as aluminum, anodized
`aluminum, or ceramic. An example of such a CVD apparatus
`is described in U.S. Pat. No. 5,558,717 entitled “CVD
`Processing Chamber,” issued to Zhao et al. The 5,558,717
`patent is assigned to Applied Materials, Inc., the assignee of
`the present invention, and is hereby incorporated by refer-
`ence in its entirety. The pedestal 104 may be formed from
`any process-compatible material,
`including, aluminum,
`anodized aluminum, aluminum nitride, or aluminum oxide
`(A1203 or alumina).
`A processor 114 is in electrical communication with the
`apparatus 26 to regulate the operations thereof. Typically,
`
`Page 11 ofl6
`
`Page 11 of 16
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`

`

`US 6,204,174 B1
`
`5
`
`the processor 114 is part of a single-board computer (SBC),
`that includes analog and digital input/output boards, inter-
`face boards and stepper motor controller boards. Various
`components of the CVD apparatus 26 conform to the Versa
`Modular European (VME) standard which defines board,
`card cage, as well as connector type and dimensions. The
`VME standard also defines the bus structure as having a
`16-bit data bus and a 24-bit address bus. Functioning as a
`controller,
`the processor 114 executes system control
`software, which is a computer program stored in a memory
`116, electronically coupled to processor 114. Any type of
`memory device may be employed, such as a hard disk drive,
`a floppy disk drive, a card rack or a combination thereof. The
`processor 114 operates under the control of the system
`control software, which includes sets of instructions that
`dictate the timing, mixture of gases, process chamber
`pressure, process chamber temperature, microwave power
`levels, pedestal position, and other parameters of a particular
`process, discussed more fully below with respect to FIG. 8.
`Referring again to FIG. 3, during a deposition procedure,
`the vacuum lid 36 is placed in the closed position. The
`heater/lift assembly 102 places the support pedestal 104 in
`a processing position 118, disposed proximate to the vacuum
`lid 36. When placed in the processing position 118,
`the
`pedestal 104 is surrounded by the process chamber liner 106
`and the annular flow channel 110.
`In this fashion,
`the
`pedestal 104 is located proximate to the gas distribution
`plate 62. Deposition and carrier gases are supplied via the
`supply lines 98 into the gas mixing manifold 96. The gas
`mixing manifold 96 causes the aforementioned gases to
`intermingle, forming the process gas, the path of which is
`shown as an arrow 126. Specifically, the process gas flows
`through the conduit 100, into the gas distribution assembly
`46, and through the apertures 82 in the gas dispersion plate
`62. In this fashion, the process gas travels into the process
`chamber 32 and is vented toward the pedestal 104, where a
`wafer (not shown) would be positioned and is uniformly
`radially distributed there across in a laminar flow.
`The deposition process performed in CVD apparatus 26
`can be either a thermal process or a plasma-enhanced
`process. In a plasma-enhanced process, an RF power supply
`122 is included and in electrical communication with the
`
`process chamber 32 to apply electrical power between the
`gas distribution 62 plate and the pedestal 104.
`In this
`fashion, a process gas disposed therein is excited to form a
`plasma within the cylindrical region between the gas distri-
`bution plate 62 and the pedestal 104, defining a reaction
`region 124. Constituents of the plasma react to deposit a
`desired film on the surface of the semiconductor wafer
`
`supported on pedestal 104. Typically, the RF power supply
`122 provides mixed frequency RF power in the range of
`13.56 MHZ to 360 KHZ, inclusive. The mixed frequency RF
`power enhances the decomposition of reactive species intro-
`duced into the process chamber 32.
`Were the deposition process thermal in nature, the RF
`power supply 122 could be abrogated. In a thermal deposi-
`tion process, the process gas mixture reacts thermally to
`deposit the desired films on the surface of a semiconductor
`wafer (not shown) supported on pedestal 104. To that end,
`the pedestal 104 is resistively heated to provide thermal
`energy for the reaction.
`During the deposition process it is beneficial to reduce the
`condensation of the process gases. To that end, the plasma
`generated during a plasma-enhanced deposition process
`heats the entire process chamber 32, including the chamber
`walls 126 surrounding the exhaust passageway 128 and the
`shut-off valve 130. In the absence of a plasma, e.g., during
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`6
`liquid is circulated
`a thermal deposition process, a hot
`through the walls 126 of the process chamber 32 to maintain
`the process chamber 32 at an elevated temperature. Fluids
`used to heat the process chamber walls 126 include the
`typical
`fluid types,
`i.e., water-based ethylene glycol or
`oil-based thermal transfer fluids. The aforementioned heat-
`
`ing reduces the accumulation of volatile reactants in the
`process chamber 32 by reducing the condensation of the
`process gas on the walls 126 and in the aforementioned
`passages.
`The portion of the process gas that is not deposited or does
`not condensate, is evacuated from the process chamber 32
`by a vacuum pump (not shown). Specifically, the gases are
`exhausted through an annular, slot 132 surrounding the
`reaction region 124 and into the annular flow channel 110.
`The annular slot 132 and the annular flow channel 110 is
`
`defined by the gap between vacuum lid 36 and chamber liner
`126. Both the annular slot 132 and the annular flow channel
`
`110 have circular symmetry to provide uniform flow of
`process gases over the pedestal 104 so as to deposit a
`uniform film on the wafer (not shown).
`the gases flow
`From the annular flow channel 110,
`through a lateral flow channel 134 in fluid communication
`therewith, past a viewing port (not shown),
`through the
`exhaust passageway 128, past the vacuum shut-off valve
`130, and into an exhaust outlet 136 that connects to the
`external vacuum pump (not shown).
`The interface between a user and the processor 114 is via
`a CRT monitor 138 and light pen 140, shown in FIG. 4,
`which is a simplified diagram of the CRT monitor and CVD
`apparatus 26 in a substrate processing system 142, which
`may include one or more process chambers. In the preferred
`embodiment two monitors 138 are used, one mounted in a
`clean room wall 144 for the operators and the other behind
`the wall for the service technicians. The CRT monitors 138
`
`simultaneously display the same information, but only one
`light pen 140 is enabled for data input during any given time.
`Alight sensor (not shown) in the tip of light pen 140 detects
`light emitted by the CRT monitor 138. To select a particular
`screen or function, the operator touches a designated area of
`the CRT monitor 138 and pushes a button (not shown) on the
`light 140. The touched area provides a visual response, such
`as a change in color, or a new menu or screen being
`displayed, confirming communication between the light pen
`140 and the CRT monitor 138. Other input devices, such as
`a keyboard, mouse, or other pointing or communication
`device, may be used instead of or in addition to the light pen
`140 to allow the user to communicate with the processor
`114.
`
`The process for depositing the film can be implemented
`using a computer program product that is executed by the
`processor 114. The computer program code can be written in
`any conventional computer readable programming lan-
`guage:
`for example, 68000 assembly language, C, C++,
`Pascal, Fortran or others. Suitable program code is entered
`into a single file, or multiple files, using a conventional text
`editor, and stored or embodied in a computer usable
`medium, such as the memory 116. If the entered code text is
`in a high level language,
`the code is compiled, and the
`resultant compiler code is then linked with an object code of
`precompiled WindowsTM library routines. To execute the
`linked, compiled object code the system user invokes the
`object code, causing the processor 114 to load the code in the
`memory 116. The processor 114 then reads and executes the
`code to perform the tasks identified in the program.
`Referring to both FIGS. 4 and 5, shown is an illustrative
`block diagram of the hierarchical control structure of the
`
`Page 12 of 16
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`Page 12 of 16
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`

`

`US 6,204,174 B1
`
`7
`system control software, computer program 146, according
`to a specific embodiment. Using the light pen 140, a user
`enters a process set number and process chamber number
`into a process selector subroutine 148 in response to menus
`or screens displayed on the CRT monitor 138. The process
`sets are predetermined sets of process parameters necessary
`to carry out specified processes, and are identified by pre-
`defined set numbers. The process selector subroutine 148
`identifies
`the desired apparatus 26 and (ii) the desired set
`of process parameters needed to operate the process cham-
`ber 32 for performing the desired process. The process
`parameters for performing a specific process relate to pro-
`cess conditions such as, for example, process gas composi-
`tion and flow rates, temperature, pressure, plasma conditions
`such as RF power levels and the RF frequency, cooling gas
`pressure, and process chamber wall
`temperature. These
`parameters are provided to the user in the form of a recipe,
`and are entered utilizing the light pen/CRT monitor inter-
`face. The signals for monitoring the process are provided by
`the analog and digital input boards of the system controller,
`and the signals for controlling the process are output on the
`analog and digital output boards of CVD apparatus.
`A process sequencer subroutine 150 comprises program
`code for accepting the identified process chamber 32 and set
`of process parameters from the process selector subroutine
`148, and for controlling operation of the various process
`chambers. Multiple users can enter process set numbers and
`process chamber numbers, or a user can enter multiple
`process set numbers and process chamber numbers, so the
`sequencer subroutine 150 operates to schedule the selected
`processes in the desired sequence. Preferably, the sequencer
`subroutine 150 includes a program code to perform the steps
`of
`monitoring the operation of the process chambers to
`determine if the process chambers are being used,
`(ii)
`determining what processes are being carried out in the
`process chambers being used, and (iii) executing the desired
`process based on availability of a process chamber 32 and
`type of process to be carried out. Conventional methods of
`monitoring the process chambers can be used, such as
`polling. When scheduling which process is to be executed,
`sequencer subroutine 150 takes into consideration the
`present condition of the process chamber 32 being used in
`comparison with the desired process conditions for a
`selected process, or the “age” of each particular user entered
`request, or any other relevant factor a system programmer
`desires to include for determining scheduling priorities.
`Once the sequencer subroutine 150 determines which
`process chamber and process set combination is going to be
`executed next, the sequencer subroutine 150 initiates execu-
`tion of the process set by passing the particular process set
`parameters to a process chamber manager subroutine 152,
`154 and 156, which controls multiple processing tasks in the
`process chamber 32 according to the process set determined
`by the sequencer subroutine 150. For example, the process
`chamber manager subroutine 152 comprises program code
`for controlling sputtering and CVD process operations in the
`process chamber 32. The process chamber manager subrou-
`tines 152, 154 and 156 also control execution of various
`process chamber component subroutines that control opera-
`tion of the process chamber components necessary to carry
`out the selected process set. Examples of process chamber
`component subroutines are substrate positioning subroutine
`160, process gas control subroutine 162, pressure control
`subroutine 164, heater control subroutine 166, and plasma
`control subroutine 168. Those having ordinary skill in the art
`will readily recognize that other process chamber control
`subroutines can be included depending on what processes
`
`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`are to be performed in the process chamber 32. In operation,
`the process chamber manager subroutine 152 selectively
`schedules or calls the process component subroutines in
`accordance with the particular process set being executed.
`The process chamber manager subroutine 152 schedules the
`process component subroutines much like the sequencer
`subroutine 150 schedules which process chamber 32 and
`process set are to be executed next. Typically, the process
`chamber manager subroutine 152 includes steps of moni-
`toring the various process chamber components, determin-
`ing which components need to be operated based on the
`process parameters for the process set to be executed, and
`causing execution of a process chamber component subrou-
`tine responsive to the monitoring and determining steps.
`Referring to both FIGS. 4 and 5, the substrate positioning
`subroutine 160 comprises program code for controlling
`process chamber components that are used to load the
`substrate (not shown) onto the pedestal 104 and, optionally,
`to lift a substrate (not shown), disposed thereon, to a desired
`height in the process chamber 32 to control the spacing
`between the substrate (not shown) and the gas distribution
`plate 62. When the substrate (not shown) is loaded into the
`process chamber 32, the pedestal 104 is lowered to receive
`the substrate, and thereafter, the pedestal 104 is raised to the
`desired height in the process chamber 32, to maintain the
`substrate (not shown) at a first distance or spacing from the
`gas distribution plate 62 during the CVD process.
`In
`operation, the substrate positioning subroutine 160 controls
`movement of the pedestal 104 in response to process set
`parameters related to the support height that are transferred
`from the process chamber manager subroutine 152.
`The process gas control subroutine 162 has program code
`for controlling process gas composition and flow rates. The
`process gas control subroutine 162 controls the open/close
`position of the safety shut-off valves (not shown), and also
`ramps up/down the mass flow controllers to obtain the
`desired gas flow rate. The process gas control subroutine 162
`is invoked by the process chamber manager subroutine 152,
`as are all process chamber component subroutines, and
`receives from the process chamber manager subroutine
`process parameters related to the desired gas flow rates.
`Typically, the process gas control subroutine 162 operates by
`opening the gas supply lines and repeatedly
`reading the
`necessary mass flow controllers, (ii) comparing the readings
`to the desired flow rates received from the process chamber
`manager subroutine 152, and (iii) adjusting the flow rates of
`the gas supply lines as necessary. Furthermore, the process
`gas control subroutine 162 includes steps for monitoring the
`gas flow rates for unsafe rates and for activating the safety
`shut-off valves when an unsafe condition is detected.
`
`In some processes, an inert gas such as helium or argon is
`flowed into the process chamber 32 to stabilize the pressure
`in the process chamber 32 before reactive process gases are
`introduced. For these processes,
`the process gas control
`subroutine 162 is programmed to include steps for flowing
`the inert gas into the process chamber 32 for an amount of
`time necessary to stabilize the pressure in the process
`chamber 32, and then the steps described above would be
`carried out. Additionally, when a process gas is to be
`vaporized from a liquid precursor, for example, tetraethy-
`lorthosilane (“TEOS”), the process gas control subroutine
`162 is written to include steps for bubbling a delivery gas,
`such as helium, through the liquid precursor in a bubbler
`assembly or introducing a carrier gas, such as helium or
`nitrogen, to a liquid injection system. When a bubbler is
`used for
`this type of process,
`the process gas control
`subroutine 162 regulates the flow of the delivery gas, the
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`US 6,204,174 B1
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`9
`pressure in the bubbler, and the bubbler temperature in order
`to obtain the desired process gas flow rates. As discussed
`above, the desired process gas flow rates are transferred to
`the process gas control subroutine 162 as process param-
`eters. Furthermore, the process gas control subroutine 162
`includes steps for obtaining the necessary delivery gas flow
`rate, bubbler pressure, and bubbler temperature for the
`desired process gas flow rate by accessing a stored table
`containing the necessary value