Substrate processing systems including gas delivery system with reduced dead legs

A gas delivery system includes a 2-port valve including a first valve located between a first port and a second port. A 4-port valve includes a first node connected to a first port and a second port. A bypass path is located between the third port and the fourth port. A second node is located along the bypass path. A second valve is located between the first node and the second node. A manifold block defines gas flow channels configured to connect the first port of the 4-port valve to a first inlet, configured to connect the second port of the 4-port valve to the first port of the 2-port valve, the third port of the 4-port valve to a second inlet, the second port of the 2-port valve to a first outlet, and the fourth port of the 4-port valve to a second outlet.

FIELD

The present disclosure relates to substrate processing systems, and more particularly to gas delivery systems for substrate processing systems including reduced dead legs.

BACKGROUND

Substrate processing systems for performing deposition and/or etching typically include a processing chamber with a pedestal. A substrate such as a semiconductor wafer may be arranged on the pedestal during processing. A process gas mixture including one or more precursors may be introduced into the processing chamber to deposit film on the substrate or to etch the substrate. In some substrate processing systems, radio frequency (RF) plasma can be struck in the processing chamber and/or an RF bias on the pedestal may be used to activate chemical reactions.

Various gas flow paths in the gas delivery system are used to deliver process gases, carrier gases, oxidizing gases, precursor gases and/or purge gases to the processing chamber. The gas flow paths are defined by via tubing, valves, manifolds and gas flow channels in a valve inlet block. Gas may be delivered by a gas flow channel during one portion of the process and gas may not be delivered during other portions of the process. In other words, gas such as a vaporized precursor gas may remain in the gas flow channel temporarily unless a purge process is performed to clear the gas flow channel. Portions of gas flow channels that hold stagnant gases are called dead legs. Stagnant gas in the dead legs may decompose and cause defects on the substrate.

SUMMARY

A gas delivery system for a substrate processing system includes a 2-port valve including a first port and a second port and a first valve located between the first port and the second port. A 4-port valve includes a first port, a second port, a third port and a fourth port. A first node is connected to the first port and the second port. A bypass path is located between the third port and the fourth port. A second node is located along the bypass path between the third port and the fourth port. A second valve is located between the first node and the second node. A manifold block defines gas flow channels configured to connect the first port of the 4-port valve to a first inlet, configured to connect the second port of the 4-port valve to the first port of the 2-port valve, configured to connect the third port of the 4-port valve to a second inlet, configured to connect the second port of the 2-port valve to a first outlet, and configured to connect the fourth port of the 4-port valve to a second outlet.

In other features, gas delivery system includes a first gas source, a second gas source; a manifold connected to the first inlet. A third valve selectively connects the first gas source to the manifold. A fourth valve selectively connects the second gas source to the manifold.

In other features, the first gas source supplies a push gas, the second gas source supplies a dose gas, and the second outlet is connected to a processing chamber. The dose gas source includes an ampoule supplying vaporized precursor.

In other features, the gas delivery system further includes a controller configured to set states of the first valve, the second valve, the third valve and the fourth valve in a diverting mode. During the diverting mode, the first valve is open, the second valve is closed, the third valve is open and the fourth valve is closed.

In other features, the controller is further configured to set the states of the first valve, the second valve, the third valve and the fourth valve in a dosing mode after the diverting mode. During the dosing mode, the first valve is closed, the second valve is open, the third valve is open and the fourth valve is open.

In other features, a dead leg is created between the first node and an inlet of the first valve during the dosing period. The dead leg defines a volume less than 2.5 ml. There is no deadleg volume during the diverting mode.

A substrate processing system includes a processing chamber including a gas distribution device connected to the first outlet of the manifold of the gas delivery system, a substrate support, and an RF generator. A controller is configured to strike plasma between the gas distribution device and the substrate support during a dosing mode.

A gas delivery system for a substrate processing system includes a first 3-port valve including a first port, a second port, a third port, a bypass path and a first node. A first valve is located between the second port and the first node. The bypass path and the first node are located between the first port and the third port. The gas delivery system includes a second 3-port valve including a first port, a second port, a third port, a second node, and a bypass path. A second valve is located between the first port and the second node. The bypass path and the second node are located between the second port and the third port. A manifold block defines gas flow channels configured to connect the first port of the first 3-port valve to a first inlet, configured to connect the second port of the first 3-port valve to a first outlet, configured to connect the second port of the second 3-port valve to a second inlet, configured to connect the third port of the first 3-port valve to the first port of the second 3-port valve, and configured to connect the third port of the second 3-port valve to a second outlet.

In other features, the gas delivery system further includes a first gas source, a second gas source, a manifold connected to the first port of the first 3-port valve, a third valve selectively connecting the first gas source to the manifold, and a fourth valve selectively connecting the second gas source to the manifold.

In other features, the first gas source supplies a push gas, the second gas source supplies a dose gas, and the second outlet is connected to a processing chamber.

In other features, a controller is configured to control the first valve, the second valve, the third valve and the fourth valve into a diverting mode. During the diverting mode, the first valve is open, the second valve is closed, the third valve is open and the fourth valve is closed.

In other features, the controller is further configured to control the first valve, the second valve, the third valve and the fourth valve in a dosing mode after the diverting mode. During the dosing mode, the first valve is closed, the second valve is open, the third valve is open and the fourth valve is open.

In other features, a dead leg is created between the first node and an inlet of the second valve. The dead leg occurs during the diverting mode. The dose gas source includes an ampoule supplying vaporized precursor. The dead leg defines a volume less than 2.5 ml.

A substrate processing system includes a processing chamber including a gas distribution device connected to the first outlet of the gas delivery system, a substrate support, and an RF generator. A controller is configured to strike plasma between the gas distribution device and the substrate support during dosing.

DETAILED DESCRIPTION

Several valve assembly arrangements according to the present disclosure significantly reduce defects during substrate processing by reducing dead leg volume when delivering process gas mixtures such as precursor gas and/or vaporized precursor. In a first valve assembly, a combination of two 3-port valves is used to reduce dead leg volume. In a second valve assembly, a combination of a 4-port valve and a 2-port valve are used to reduce dead leg volume.

Referring now toFIG.1, an example of a substrate processing system100includes a processing chamber112with a reaction volume. In some examples, a plasma-enhanced chemical vapor deposition (CVD) or plasma enhanced atomic layer deposition (ALD) process may be performed, although other etching, deposition or other substrate processes may be performed.

Process gas mixtures may be supplied to the processing chamber112using a gas distribution device114such as showerhead. In some examples, the showerhead is a chandelier-type showerhead. A substrate118such as a semiconductor wafer may be arranged on a substrate support116during processing. The substrate support116may include a pedestal, an electrostatic chuck, a mechanical chuck or other type of substrate support.

One or more gas delivery systems120-1,120-2120-3, . . . may include one or more gas sources122-1,122-2, . . . , and122-N(collectively gas sources122), where N is an integer greater than one. Valves124-1,124-2, . . . , and124-N (collectively valves124), mass flow controllers126-1,126-2, . . . , and126-N(collectively mass flow controllers126), or other flow control devices may be used to controllably supply one or more gases to a manifold130, which supplies a gas mixture via a valve V46, a manifold131, and a valve V164to the processing chamber112. In some examples, the manifold131is a heated injector manifold. One or more additional gas delivery systems may be provided to supply gases or gas mixtures in other locations. A divert path including a valve V166selectively diverts gas to vacuum or exhaust.

A controller140may be used to monitor process parameters such as temperature, pressure, etc. (using one or more sensors141) and to control process timing. The controller140may be used to control process devices such as gas delivery systems120-1,120-2and120-3, a substrate support heater142, and/or an RF plasma generator146. The controller140may also be used to evacuate the processing chamber112using a valve150and pump152.

The RF plasma generator146generates the RF plasma in the processing chamber. The RF plasma generator146may be an inductive or capacitive-type RF plasma generator. In some examples, the RF plasma generator146may include an RF supply160and a matching and distribution network162. While the RF plasma generator146is shown connected to the gas distribution device114and the substrate support is grounded or floating, the RF plasma generator146can be connected to the substrate support116and the gas distribution device114can be grounded or floating.

Vaporized precursor can be supplied to the manifold131by an ampoule190that supplies vaporized liquid precursor. A carrier gas180is supplied via valve182, MFC184, and valve186. Additional valves V213, V205, V214and V55control delivery of the carrier gas and/or delivery of the carrier gas and vaporized precursor from the ampoule190. In some examples, the ampoule190is heated by a heater194. The ampoule190may further include one or more temperature sensors192to detect a temperature of the precursor liquid in the ampoule190. The controller140may be used to sense the temperature of the precursor liquid and to control the heater194to heat the precursor liquid to a predetermined temperature.

As can be appreciated, when valve V213is closed and valves V205and V214are open, carrier gas flows through the ampoule190and entrains vaporized precursor. The mixture of carrier gas and vaporized precursor is delivered by valve V55to the manifold131and by the valve V164to the gas distribution device114. In some examples, a gas delivery system120-2delivers a gas mixture to a manifold196and valves V44and V165control delivery of the gases to the processing chamber. In some examples, a valve V162provides a secondary purge gas mixture to the stem of the showerhead. In some examples, a gas delivery system120-3delivers gases to a manifold198and valves V69and V167control delivery of the gases to vacuum, exhaust or the processing chamber.

Referring now toFIG.2, a gas delivery assembly200is shown to include one or more valve assemblies220-1,220-2. . . and220-4(collectively valve assemblies220) and a valve manifold228. The valve assemblies220are configured to control the flow of fluid(s) into and out of the valve manifold228. In this regard, the valve manifold228includes a body274defining one or more gas channels276-1,276-2. . . and276-N (collectively gas channels276), first, second and third inlets278,280,282, and first and second outlets284,285.

The first gas channel276-1extends from, and fluidly communicates with, the first inlet278of the valve manifold228and the second valve assembly220-2. The second gas channel276-2extends from the first gas channel276-1to the first valve assembly220-1. The third gas channel276-3extends from the first valve assembly220-1to the first outlet284of the valve manifold228. The fourth gas channel276-4extends from the second valve assembly220-2to the second outlet285of the valve manifold228.

The gas delivery assembly200is operated in at least three modes, such as a divert mode, a supply mode, and a standby mode. The gas delivery assembly200may operate in a continuous cycle such that the divert mode precedes the supply mode, the supply mode precedes the standby mode, and the standby mode precedes the divert mode. In the divert mode, stale precursor in the gas channels276may be replaced with fresh precursor. In the supply mode, vaporized precursor is supplied to the processing chamber. In the standby mode, vaporized precursor is not supplied and is not diverted.

When supplying vaporized precursor, the first valve assembly220-1is closed and the second valve assembly220-2is open. The vaporized precursor gas is supplied through the first gas channel276-1from the first inlet278to the second valve assembly220-2. The vaporized precursor gas flows through the second valve assembly220-2and the fourth gas channel276-4to the processing chamber or other portion of the substrate processing system.

During the standby mode, the first and second valve assemblies220-1,220-2are closed such that flow of vaporized precursor from the first inlet278is prevented. Accordingly, during the standby mode, vaporized precursor gas remains in the first gas channel276-1. In some conditions, the stagnant vaporized precursor in the first gas channel276-1may condense into particles. Stagnant vaporized precursor that later enters the processing chamber can cause defects.

Prior to supplying vaporized precursor to the processing chamber in the supply mode, the vaporized precursor is diverted and discarded such that the stale vaporized precursor in the gas channel276-1is replaced by fresh precursor. When diverting the vaporized precursor, the first valve assembly220-1is open and the second valve assembly220-2is closed. When vaporized precursor gas is supplied through the first gas channel276-1from the first inlet278, the vaporized precursor gas flows out of the valve manifold228through the second gas channel276-2, the first valve assembly220-1and the third gas channel276-3.

While the divert mode provides some improvement, not all of the stale vaporized precursor is removed. The gas delivery assembly200has a dead-leg volume290that is located downstream from the second gas channel276-2and upstream from the second valve assembly220-2. Specifically, the vaporized precursor that stagnates in the dead-leg volume during the standby mode is not diverted through the first valve assembly220-1during the divert mode. Vaporized precursor that was trapped in the dead-leg volume290during the divert mode still flows into the processing chamber from the first and fourth gas channels276-1,276-4during the supply mode and creates defects in the substrate.

Referring now toFIG.3, a first valve assembly300for a gas delivery system includes a first 3-port valve302and a second 3-port valve304. The first 3-port valve302includes a first port receiving gas from an outlet of the manifold131. The first port is connected to a bypass path330and to a first node310. A second port (or divert path320) of the first 3-port valve302is connected through a first valve V166A to the first node310(valved path332). A third port is connected to the bypass path330and to the first node310.

A first port of the second 3-port valve304is connected by a valved path342through a second valve V164A to a second node314. A second port of the second 3-port valve304supplies gas such as push gas and is connected to a bypass path340and to the second node314. A third port is connected to the bypass path340and to the second node314. The third port is connected to the processing chamber.

Referring now toFIG.4, the first valve assembly300is shown in a diverting mode. The valve V46supplies gas through the manifold131(and the valve V55to the ampoule190is closed). The gas delivered to the first port of the first 3-port valve302is diverted at the first node310through the first valve V166A. The second 3-port valve304is closed. A dead leg occurs between the first node310and the inlet of the second valve V164A.

Referring now toFIG.5, the first valve assembly300is shown during a dosing mode. The valve V46supplies gas through the manifold131(and the valve V55to the ampoule190is open). The vaporized precursor gas mixture from the ampoule190is delivered to the first port of the first 3-port valve302and is not diverted at the first node310by the first valve V166A (which is closed). Rather, the vaporized precursor gas mixture is delivered to the first port of the second 3-port valve304(the second valve V164A is open) to the second node314. The mixture of the push gas and the vaporized precursor is delivered to the processing chamber.

In some examples, the valve assembly300defines a very small volume between the first node310and the inlet of the second valve V164A. In some examples, the volume is less than 4 ml. In some examples, the volume is less than 3 ml. In other examples, the volume is 2.3 ml. The dose flow to the processing chamber travels through the first and second valves V166A and V164A, respectively. The flow to the processing chamber expands out of the second valve V164A into an inert stream from the manifold198. During the diverting step, a section between the first and second valves V166A and V164A is not purged. During the dosing step, the section between the first and second valves V166A and V164A is purged to the processing chamber.

Referring now toFIG.6, a portion of the first valve assembly is shown to include a valve manifold block610and valve inlets600of the first and second 3-port valves302and304, respectively. The valve manifold block610defines a first channel620connecting the first port of the first 3-port valve302and the ampoule190. The valve manifold block610defines a second channel624connecting to the second port of the first 3-port valve302to the diverting path320. The valve manifold block610defines a third channel630connecting the third port of the first 3-port valve302to the first port of the second 3-port valve304. The valve manifold block610defines a fourth channel636that connects the manifold198to the second port of the second 3-port valve304. The valve manifold block610defines a fifth channel632connecting the third port of the second 3-port valve304to the processing chamber.

Referring now toFIG.7, a second valve assembly700includes a 2-port valve702and a 4-port valve704. The 2-port valve702includes a first port receiving gas from an outlet of the manifold131via a first node710of the 4-port valve704. A second port of the 2-port valve702is connected to a divert path720. A first valve V166B is located between the first and second ports of the 2-port valve702.

The 4-port valve704includes a first port connected to the manifold131and to the first node710. A second port of the 4-port valve704connects the first node710to the first port of the 2-port valve702. The first node710is connected to the second valve V164B of the 4-port valve704. A third port of the 4-port valve704receives gas such as push gas from the manifold198and is connected to the second node714. A fourth port of the 4-port valve704connects the second node714to the processing chamber. The 4-port valve704includes a bypass path730and a valved path732. The second valve V164B selectively allows flow from the first node710to the second node714or blocks the flow.

As can be seen inFIG.7, the first port of the 4-port valve704connects to a valved path732(at the first node710) at an angle760relative to a path of the valved path732. The second node of the 4-port valve704connects at an angle762relative to the first path. In some examples, the angle760is an acute angle that is greater than zero. In some examples, the angle760is greater than zero and less than 45 degrees. In some examples, the angle762is greater than the angle760. In some examples, the angle762is greater than 60 degrees and less than 120 degrees. In some examples, the angle762is greater than 70 degrees and less than 100 degrees.

Referring now toFIGS.8A and8B, the second valve assembly700is shown during two example diverting modes. InFIG.8A, the valve V46supplies gas through the manifold131(and the valve V55to the ampoule190is closed). The gas is delivered to the first port of the 4-port valve704(which includes the second valve V164B that is closed). The gas flows through the first node710and out the second port of the 4-port valve704to the first port of the 2-port valve702. The first valve V166B of the 2-port valve702is open so the gas flows through the 2-port valve702to the diverting path720.

InFIG.8B, the valve V46supplies gas from a first gas source through the manifold131(and the valves V213and V55are open and V205and V214are closed). The push and carrier gas are delivered from a second gas source to the first port of the 4-port valve704(which includes the second valve V164A that is closed). The gas flows through the first node710and out the second port of the 4-port valve704to the first port of the 2-port valve702. The first valve V166B of the 2-port valve702is open so the gas flows through the 2-port valve702to the diverting path720.

In bothFIGS.8A and8B, during the divert mode, the deadleg volume is zero for the second valve assembly700. In some examples, internal passages of the 4 port valve are cut at an angle in contrast to conventional valves having internal passages that are straight or parallel sections.

Referring now toFIG.9, the second valve assembly700is shown during dosing operation. The valve V46supplies gas through the manifold131(and the valve V55to the ampoule190is open). The vaporized precursor gas mixture delivered to the first port of the 4-port valve704is not diverted at the first node710(since the first valve V166B is closed). Rather, the vaporized precursor gas mixture is delivered to the inlet of the 4-port valve704(via the second valve V164B which is open) and then to the second node714. The mixture of the push gas and the vaporized precursor is delivered to the processing chamber. A dead leg occurs during dosing between the first node710and the inlet of the first valve V166B.

Referring now toFIG.10, a portion of the second valve assembly is shown to include a valve manifold block1000and valve inlets1004to the 2-port and 4-port valves702and704, respectively. The valve manifold block1000defines a first channel1010that connects to the second port of the 2-port valve702. The valve manifold block1000defines a second channel1020connecting the first port of the 2-port valve702to a first port of the 4-port valve704. The valve manifold block1000defines a third channel1050(receiving dose and carrier gas) connected to the first port of the 4-port valve704. The valve manifold block1000defines a fourth channel1040connected to the third port of the 4-port valve704(receiving push gas). The valve manifold block1000defines a fifth channel1030connected to the fourth port of the 4-port valve704(directing gases to the processing chamber).

In some examples, the second valve assembly700defines a very small volume between the first node710and the inlet of the first valve V166B. In some examples, the volume is less than 4 ml. In some examples, the volume is less than 3 ml. In other examples, the volume is 2.3 ml. Unlike the first valve assembly300, the dose flow of the second valve assembly700to the processing chamber travels through one valve (the second valve V164B). The flow to the processing chamber expands out of center port into a plenum. During the diverting step, the dead leg is cleared. During the dosing step, the gas is trapped in the dead leg.

Referring now toFIG.11, a timing diagram is shown for operating valves using the first and second valve assemblies300and700, respectively. While specific values for switching periods are shown, other periods can be used. During a soak period, a first gas mixture from a manifold is supplied to the processing chamber using the second valve V164. During a diverting period including LCD1and LCD2, the second valve V164is closed and the first valve V166is open. During LCD1, the valve V213is open to supply push gas. During LCD2, the valve V213is closed and the valves V205, V214and V55are opened to supply vaporized precursor. In some examples, the period of LCD1is 1.5 s and the period of LCD2is 1.5 s.

During Part1 of a dose period, the valves V205, V214and V55remain open. During Part1 and Part2 of the dosing period, the valve V166is closed and V164is open. The duration of Part1 will depend on gas transport times and in some examples the period is 0.05 s. In some examples, the duration of Part2 is 0.2 s. After dosing, the valve V166is opened and the valve V164is closed.