JP5608157B2 - Substrate etching system and process method and apparatus - Google Patents

Description

background

(Field)
Embodiments of the present invention generally relate to substrate processing systems and related substrate processes, such as etching / deposition processes. In one aspect, the present invention relates to an improved silicon etching system. In another aspect, the invention relates to a fast gas exchange system. In yet another aspect, the present invention relates to providing a dual etch / deposition process. In yet another aspect, the present invention relates to providing a rapid gas migration process using a system including a processing chamber and a gas delivery system while processing a substrate in the chamber.

(Description of related technology)
There are many different stages in the manufacture of microelectronic devices, and each stage involves various processes. At one stage, a specific process changes the physical and material properties of the substrate by exposing the surface of the substrate, such as a silicon substrate, to plasma. This process is known as etching and involves removing material to form holes, vias and / or other openings (referred to herein as “trenches”) in the substrate.

  Plasma etch reactors are commonly used to etch trenches in a semiconductor substrate. These reactors comprise a chamber in which the substrate is supported. At least one reactive gas is supplied to the chamber and a high frequency signal is coupled to the reactive gas to form a plasma. With this plasma, the substrate positioned in the reactor is etched. The substrate may also be coupled to a high frequency signal to apply a bias to the substrate during the etching process to improve etching performance and trench profile.

  These trench profiles often require different critical dimensions. Critical dimensions include width, depth, aspect ratio, resist selectivity, sidewall roughness, and sidewall flatness. These critical dimensions can be controlled by various factors, two of which are etch time and etch rate, which further depend on the material being etched and the type of etching system used.

  One particularly important material is silicon. TSV (Through Silicon Via) etching is a unique technique that requires low frequency bias power and a low temperature environment to form deep trenches in a silicon substrate. However, during manufacturing, silicon is generally covered by multiple layers of materials other than silicon (oxide layers, metal layers, etc. deposited on the silicon). Oxides and metals have different etching requirements than silicon, such as high frequency bias power. In addition, during the deposition step, a thin film polymer layer may be deposited over the substrate layer during trench formation to protect the trench sidewalls prior to the etching step. This polymer layer may have additional etching requirements that are different from the oxide, metal or silicon layers. These completely different requirements affect and increase the complexity of the type of etching system used.

  One type of etching system includes in-situ plasma etching. Using this first type of etching system, trenches are formed by alternately removing material from the substrate and depositing material on the substrate in a single reactor using removal and deposition plasmas. Is possible. Another type of etching system includes remote plasma etching. Using this second type of etching system, the trench can be formed as in the in-situ system, except that in the remote reactor before the plasma is introduced onto the substrate located in the primary reactor. To generate. In addition to the type of etching system, the process of etching using each system can also vary. Some etching processes employ a multi-stage scheme such as a time-sharing gas modulation (TMGM) system or a Bosch system, which includes several recipes such as an etch / deposition step or an etch / flash / deposition step. Steps are included. In the TMGM process, the surface, typically the sidewalls of the trench, is protected from further etching by etching the material for a period of time and then depositing a protective film on the pre-etched surface. These two steps are repeated as the deeper trench is formed. Different types of etching systems and processes have certain advantages and disadvantages in forming different trench profiles in different material layers.

  Unless the sidewall roughness, which is one of the critical dimensions particularly important when forming the trench, is not properly controlled, the microelectronic device becomes a defective product. During the etching cycle, material continues to be deposited and removed while forming the trench. Correspondingly, a striped pattern including a series of peaks and valleys occurs along the sidewalls of the trench, a phenomenon known as “scalloping”. Numerous large peaks and valleys increase the roughness of the trench sidewalls.

  Accordingly, there is a need for improved methods and apparatus for etching systems and processes for controlling substrate etching and reducing the roughness of the profile formed on the substrate.

Overview

  In one embodiment, a method for etching a substrate in a chamber includes depositing a protective layer on a first layer disposed on the substrate in the etch reactor, etching the protective layer in the etch reactor, The first bias power is applied during the etching of the first layer, the first layer is etched in the etching reactor, the second bias power is applied during the etching of the first layer, and the substrate is profiled by repeating the deposition process and the etching process. Forming.

  In one embodiment, a method of etching a substrate in a chamber includes depositing a polymer film on the substrate during the deposition process, etching the polymer film deposited on the substrate during the first etching process, Forming a profile in the substrate by etching the substrate during a two-etching process, wherein a first bias power is applied to the substrate during the first process and a second bias power is applied to the substrate during the second etching process Is done.

  In one embodiment, a gas delivery system includes a chamber for processing a substrate and a first gas panel in communication with the chamber by a first gas delivery line, the first gas delivery line comprising a plurality of first flow controllers. And the delivery system further comprises a second gas panel in communication with the chamber by a second gas delivery line, the second gas delivery line comprising a plurality of second flow controllers, and a plurality of first and second flow controllers Can selectively direct gas from the first and second panels to one or more exhausts in communication with the chamber and the first and second gas delivery lines, respectively.

  In one embodiment, a method for supplying gas to a chamber includes supplying a first gas to the chamber from a first gas panel through a first gas delivery line and discharging a second gas while supplying the first gas to the chamber. Directing the second gas panel through a second gas delivery line, directing the first gas to the discharge, and supplying the second gas to the chamber prior to introducing the second gas into the chamber. Thus, the first gas is removed from the chamber.

  In order that the above-described structure of the present invention may be understood in detail, a more specific description of the invention briefly summarized above will be given by way of example. Some of the embodiments are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only typical embodiments of the invention and that the invention may include other equally effective embodiments and therefore should not be construed as limiting the scope of the invention. Should.

1 is a diagram illustrating a substrate etching system according to an embodiment of the present invention. 1 shows a fast gas exchange system according to an embodiment of the present invention. FIG. 6 shows another fast gas exchange system according to an embodiment of the present invention. ~ It is a figure which shows the profile etched by the board | substrate. It is a figure which shows the conventional etching cycle. FIG. 4 is a diagram illustrating an etching cycle according to an embodiment of the present invention. It is a figure which shows the trench profile formed by the conventional method. FIG. 5 shows a trench profile formed using a method according to an embodiment of the invention. ~ FIG. 4 illustrates a gas migration process according to one embodiment of the present invention. ~ FIG. 6 illustrates another gas migration process according to an embodiment of the present invention. ~ FIG. 6 illustrates another gas migration process according to an embodiment of the present invention. 1 shows a gas delivery system according to an embodiment of the present invention.

Detailed description

  The present invention generally relates to substrate etching systems and process apparatus and methods. As described herein, the present invention is described as relating to a silicon etching system and process. However, it should be noted that aspects of the present invention are not limited to use in silicon etching and are applicable to etching other types of materials. For a better understanding of the novelty of the device of the invention and its method of use, reference will now be made to the accompanying drawings.

  A method and apparatus are provided for etching a profile such as a deep trench in a silicon substrate having an oxide layer and a metal layer deposited thereon, wherein the etching cycle is performed in situ in a single fully automated reactor. A plurality of plasma processes. Each such etching cycle includes a deposition step, a first etching step, and a second etching step. Each of these steps is an individual plasma process defined by the composition of the gas mixture fed into the chamber of the reactor that supports the substrate. During each step, a different composition of the gas mixture can be supplied to the chamber. The reactor typically includes a power source for generating and maintaining plasma (referred to herein as “source power”) and a power source for applying a bias to the substrate (referred to herein as “bias power”), Independently controlled.

  The bias power can be pulsed (eg, repeatedly releasing energy) while the source power can be applied continuously. In particular, the bias power can be pulsed using the generator pulsing capability to determine the percentage of time that the power is turned on, referred to as the “duty cycle” set by the control system. In one embodiment, the ON / OFF time of the pulsed bias power is constant throughout the etch cycle. For example, if the power is on for about 3 milliseconds and off for about 15 milliseconds, the duty cycle is about 16.67%. The pulse frequency (cycles / second, or hertz (Hz)) is equal to 1.0 divided by the sum of the ON / OFF times (seconds). For example, if the bias power is ON for about 3 milliseconds and OFF for about 15 milliseconds (total about 18 milliseconds), the pulse frequency (cycles / second) is about 55.55 Hz. In one embodiment, a special pulse profile is used whose ON / OFF timing changes during the etching cycle. In one embodiment, the etching cycle is switched between the deposition step and / or the etching step by changing the bias power applied to the substrate. By pulsing the bias power, the trench sidewall scalloping is reduced, resist selectivity is improved, etching rate is improved, and undercutting at the material interface is prevented.

  FIG. 1 is a cross-sectional view of a system such as a reactor 100 that processes various substrates and accommodates various substrate sizes. In one embodiment, reactor 100 includes source power 15, matching circuit 17, bias power 20, matching circuit 21, chamber 25, pump 30, valve 35, ceramic electrostatic chuck 40, cooling device 45, lid 50, gas nozzle 55 and A gas delivery system 102 is included. In one embodiment, the gas delivery system 102 is located in a housing 105 that is disposed immediately adjacent (eg, beneath) the chamber 25. The gas delivery system 102 selectively connects one or more gas sources located within the one or more gas panels 104 to the gas nozzle 55 to supply process gas to the chamber 25. By disposing the housing 105 close to the chamber 25, the gas transfer time when changing the gas is shortened, the gas utilization is minimized, and the waste of gas is minimized. The reactor 100 may further include an elevating device 27 for raising and lowering the chuck 40 that supports the substrate in the chamber 25. Chamber 25 further includes a body having a lower liner 22, an upper liner 23 and a door 24. The valve 35 can be disposed between the pump 30 and the chamber 25, and the pressure in the chamber 25 may be controllable. The ceramic electrostatic chuck 40 can be disposed in the chamber 25. The lid 50 can be disposed on the chamber 25. The gas nozzle 55 may include an adjustable gas nozzle having one or more outlets for selectively directing gas flow from the gas delivery system 102 to the chamber 25. The gas nozzle 55 may be capable of directing the gas flow to different regions within the chamber 25 (such as the central region and / or the lateral region of the chamber 25). In one embodiment, the gas nozzle 55 includes a first outlet that introduces gas from the top of the chamber 25 and a second that introduces gas from the side of the chamber 25 to selectively control the distribution of gas in the chamber 25. Outlet can be included. By utilizing the gas delivery system 102, at least two gas mixtures can be fed into the chamber 25 at the same rate as described in more detail below. In any embodiment, the reactor 100 is capable of using the depth of the etched trench and the thickness of the deposited film to utilize other spectral characteristics to determine the state of the reactor during trench formation in the chamber 25. It includes a spectrum monitor that can be measured. The reactor 100 can be configured to accommodate various substrate sizes, for example, substrate diameters up to about 300 mm. In operation, as described herein, the reactor 100 has an etched substrate trench sidewall profile having an angle that tapers in the range of about 85 to about 92 degrees and a depth of about 10 micrometers to about 500 micrometers. It can be configured to form an etched substrate trench.

  In one embodiment, reactor 100 is coupled to a system that includes a metal etch reactor and optionally a post metal etch passivation chamber.

  In one embodiment, source power 15 for generating and maintaining plasma for a plasma process is coupled to chamber 25 via a power generation device in housing 11 disposed on chamber 25. The source power 15 may be capable of generating a high frequency of about 12 MHz to about 13.5 MHz with a pulse capability and a power of about 10 watts to about 5000 watts, and may further include a dynamic matching circuit 17. . In one example, the source power 15 can generate a high frequency of 13 MHz having pulsing capability. The source power 15 may include a dual tunable source so that the high frequency can be changed during the etching cycle. In one embodiment, the source power 15 comprises a remote plasma source that can be attached to the reactor 100 and that can produce a high level of plasma ionization. When using a remote plasma source, the reactor 100 can further include one or more plasma distribution plates disposed on the chamber 25 to facilitate distribution of the plasma to the substrate. In one embodiment, the reactor 100 includes both in-situ source power and remote plasma source power, and plasma is generated in the remote plasma chamber using the remote plasma source power and delivered to the reactor chamber 25, In situ source power 15 maintains the generated plasma in chamber 25. In one embodiment, the etching cycle is performed while increasing or decreasing the power range, that is, the wattage of the power supply 15 during that time. Source power 15 may be pulsed during the etch cycle.

  In one embodiment, bias power 20 for applying a bias to the substrate is coupled to chamber 25 and chuck 40. The bias power 20 can generate a low power high frequency of about 2 MHz, about 10 watts to about 500 watts with pulsing capability, and can further include a dynamic matching circuit 21. In one embodiment, the bias power 20 is selectable from about 400 kHz to about 2 MHz, about 100 kHz to about 2 MHz, and about 100 kHz to about 13.56 MHz with low power of about 10 watts to about 500 watts with pulsing capability. High frequency can be generated, and further includes a dynamic matching circuit or a fixed matching circuit and a frequency tuner. In one embodiment, the etch cycle is performed while increasing or decreasing the power range, ie, the wattage of the bias power 20, during that time. In one embodiment, the etching cycle includes a deposition step, a first etching step, a second etching step, using a bias power 20 during the first etching step and increasing or decreasing the bias power 20 during the second etching step. For example, the high frequency of the bias power is increased or decreased from the first etching step to the second etching step.

  The bias power 20 may be pulsed during the etching cycle. In order to pulse the bias power 20, the high-frequency power is switched ON / OFF during the etching cycle. The pulse frequency of the bias power 20 may be about 10 Hz to about 1000 Hz, and may be about 50 Hz to about 180 Hz. In one embodiment, power ON / OFF switching is evenly distributed throughout the etching cycle. In one embodiment, the pulsing timing profile varies throughout the etch cycle and depends on the composition of the substrate. The ratio of time for switching the bias power 20 to ON, that is, the duty cycle as described above, is directly related to the pulse frequency. In one embodiment, the duty cycle is about 2% to about 40% when the pulse frequency is about 10 Hz to about 1000 Hz. In one embodiment, the duty cycle is about 5% to about 30% when the pulsed frequency is about 50 Hz to about 180 Hz. The bias power frequency and the pulse frequency can be adjusted according to the material of the substrate to be processed.

  In one embodiment, the cooling device 45 can control the temperature of the chamber 25 and the substrate in the chamber 25. The cooling device 45 can be connected at a position close to the chamber 25. The cooling device 45 can include a low-temperature cooling device (such as a below-zero thermoelectric cooling device) and can further include a direct cooling mechanism for ultra-low temperatures. The cooling device 45 can achieve a temperature in the range of about −20 ° C. to about 80 ° C. and is located near the chamber 25 to achieve a faster reaction time, improving the etching rate with some control. It may include a ramping capability that enables it. In one embodiment, the cooling device 45 can achieve a temperature of about −10 ° C. to about 60 ° C. and is located near the chamber 25 to achieve a faster reaction time. In one embodiment, the cooling device 45 can reduce the temperature in the chamber 25 to about −10 ° C. to about −20 ° C.

  In one embodiment, the reactor 100 can maintain a chamber pressure of about 10 mTorr to about 1000 mTorr with a pump 30 and a valve 35 that is coupled to the chamber 25. It is possible to further improve the trench profile by adjusting the chamber pressure during the etch cycle. For example, when switching from a deposition step to an etching step, the chamber pressure is rapidly reduced or increased. The pump 30 can include a turbo pump (eg, 2600 L / sec turbo pump) that can process a flow rate between about 100 sccm and about 1000 sccm throughout the chamber 25. Along with pump 30, valve 35 may include a throttle gate valve to facilitate control of process flow and pressure changes with fast reaction times. The reactor 100 can further include a dual manometer for measuring the pressure in the chamber 25. In one embodiment, the reactor 100 can maintain a dynamic pressure of about 10 mTorr to about 250 mTorr during the etching cycle. Optionally, an automatic throttling gate valve controller or a valve with pre-set control points may be utilized, and the dynamic pressure can be maintained at the set point while changing the flow parameters.

FIG. 2 is a schematic diagram of one embodiment of a gas delivery system 102 having a fast gas exchanger 200. Fast gas exchanger 200 directs first flow controller 240, second flow controller 230, a number of optional flow restrictors 260 and optionally gas to chamber 25 (shown in FIG. 1) via outlets 270, 280. A housing 205 (such as the housing 105 described above) that houses a valve 250 for carrying out the discharge and a discharge part 290 for discarding the gas to a chamber discharge part downstream of the pump 30. Specifically, although four flow restrictors 260 and eight valves 250 are shown in FIG. 2, the number of flow restrictors 260 and valves 250 may be varied. The first flow controller 240 communicates with the outlet 270 via the flow line 272, and the flow line 272 communicates with the outlet flow line 273. The second flow controller 230 communicates with the outlet 270 via the flow line 271, and the flow line 271 also communicates with the outlet flow line 273. Each of the first and second flow controllers communicates with the discharge unit 290 via each of the flow lines 272 and 271, and each of the flow lines 272 and 271 is connected to the discharge flow line 291. The first flow controller 240 is also in communication with the outlet 280 separately via the flow line 282, and the flow line 282 is in communication with the outlet flow line 283. The second flow controller 230 also communicates with the outlet 280 via the flow line 281, and the flow line 281 communicates with the outlet flow line 283. Each of the first and second flow controllers communicates with the discharge unit 290 via each of the flow lines 282 and 281, and each of the flow lines 282 and 281 is connected to the discharge flow line 291. One or more of the flow paths from the first and second flow controllers through the flow lines 271, 272, 281, 282, and 291 following the discharge section 290, respectively, can be configured to pre-flow gas paths as will be described in more detail below. Can be defined. One or more optional flow restrictors 260 and valves 250 are positioned between the first and second flow controllers 240, 230, between the outlets 270, 280 and the exhaust 290 to process gas outlets 270, 280 and exhaust. Transmission to the unit 290 can be controlled. The distribution of gas into the chamber 25 may be selectively controlled by communicating the outlets 270, 280 with one or more outlets of the gas nozzle 55 (described above). The high-speed gas exchanger 200, particularly the first and second flow controllers 240 and 230, are connected to the first gas panel 220 and the second gas panel 210, respectively, for supplying process gas using the high-speed gas exchanger 200. . The first and second gas panels 210 and 220 can be connected to the high-speed gas exchanger 200 through the first flow line 217 and the second flow line 227. Each of the first and second gas panels may include one or more gas supply sources 215, 225, and one or more gases may be sent through the first and second flow lines 217, 227 to the high-speed gas exchanger 200, As a result, it can be supplied to the chamber 25. When configured for silicon etching, the fast gas exchanger 200 supplies a first gas (such as sulfur hexafluoride (SF ₆ )) from the first gas panel 210 to the chamber 25 during the first and second etching steps. Also, a second gas (such as perfluorocyclobutane (C ₄ F ₈ )) is supplied to the chamber 25 from the second gas panel 220 during the deposition step. In one example, the first gas panel 210 and the second gas panel 220 can deliver SF ₆ and C ₄ F ₈ at about 1000 sccm, helium at about 500 sccm, and oxygen (O ₂ ) and argon at about 200 sccm. In one embodiment, a third gas panel having a plasma sustaining gas (such as argon) is coupled to the fast gas exchanger 200, which can continuously supply gas to the chamber 25 during the etching and deposition steps. is there.

  During operation, as the gas from the first gas panel 210 is supplied to the chamber 25, the first flow controller 240 passes the gas to the outlet 280 via the flow line 282 and to the outlet 270 via the flow line 272. Or it can be directed to both outlets. By using an optional flow restrictor 260, the flow of gas in the high-speed gas exchanger 200 can be controlled. While gas is being supplied to the chamber 25, the valve 250 can open the flow path to the chamber 25 and close the discharge flow line 291 and thus the flow path to the discharge portion 290. During the etching cycle switching step, the gas from the second gas panel 220 can be supplied to the chamber 25 in the same manner as the first gas panel 210. While supplying gas from the second gas panel 220 to the chamber 25, the valve 250 closes the flow path from the first gas panel 210 to the chamber 25, and flows to the discharge flow line 291 and thus to the discharge unit 290. The path can be opened and the gas in the flow line can be discarded. In one example, gas is supplied from the first gas panel 210 to the chamber 250 during the deposition step, and gas is supplied from the second gas panel 220 to the chamber 25 during the etching step. Both gas panels 220, 210 can be used for both deposition and etching steps.

In another embodiment, a high speed gas exchanger is utilized, as shown in FIG. The high-speed gas exchanger 300 includes a first flow controller 340, a second flow controller 345, and a second flow controller 345 that are in communication with each other to selectively direct gas into a chamber 310 (such as chamber 25 of reactor 100 shown in FIG. 1). A housing 305 (such as the housing 105 described above) containing the third flow controller 347, the first discharge part 360 and / or the second discharge part 370 is included. The high-speed gas exchanger 300, particularly the first flow controller 340, can be connected to the first gas panel 320 via the flow line 341. In some embodiments, in conjunction with silicon etching, the first gas panel 320 includes a plurality of gas sources 322 and includes sulfur hexafluoride, oxygen, argon, trifluoromethane (CHF ₃ ), and / or helium. However, it is not limited to these. Each of the flow controllers 340, 345, 347 can include a flow control valve that can direct gas to the exhausts 360, 370 and / or the chamber 310. The flow control valve allows for a quick response and can include pneumatic actuators for pneumatic operation to provide many flow configurations. In addition, the flow controllers 340, 345, 347 may communicate with an operating system for controlling and monitoring the operation of the valves. The flow restrictors 346, 348 may optionally be coupled to a third flow controller 347 to restrict flow to the second exhaust 370 and / or the chamber 310.

  In one embodiment, the first flow controller 340 sends gas to the first exhaust 360 via the flow line 343 (a high-speed exhaust path is defined as described in more detail below) and / or the flow line. It is configured to direct to the second flow controller 345 via 342. The second flow controller 345 may be configured to direct gas to the chamber 310 via the flow line 325 and / or via the flow line 344 to the third flow controller 347. The third flow controller 347 may be configured to direct gas through the optional flow restrictor 348 through the flow line 349 to the second outlet 370 (the preflow gas path described in more detail below is Defined) and / or directed through the flow line 321 through an optional flow restrictor 346 to the chamber 310, which may be in communication with the flow line 325.

  The fast gas exchanger 300 is also disposed within the housing 305 and in communication with each other, a first flow controller 350 for directing gas to the chamber 310, the first exhaust 360 and / or the second exhaust 370, A second flow controller 355 and a third flow controller 357 can also be included. The high-speed gas exchanger 300, particularly the first flow controller 350, can be connected to the second gas panel 330 via the flow line 351. In certain embodiments, in conjunction with silicon etching, the second gas panel 330 includes a plurality of gas sources 332, including but not limited to perfluorocyclobutane, oxygen, argon, trifluoromethane, and / or helium. . Each of the flow controllers 350, 355, 357 may include a flow control valve that can direct gas to the exhausts 360, 370 and / or the chamber 310. The flow control valve allows for a quick response and can include pneumatic operations to provide many flow configurations. In addition, the flow controllers 350, 355, 357 may communicate with an operating system for controlling and monitoring the operation of the valves. The flow restrictors 356, 358 can optionally be coupled to a third flow controller 347 to restrict flow to the second exhaust 370 and / or the chamber 310.

  In one embodiment, the first flow controller 350 sends gas to the first exhaust 360 via the flow line 353 (a high speed exhaust path is defined as described in more detail below) and / or the flow line. It is configured to direct to the second flow controller 355 via 352. The second flow controller 355 can be configured to direct gas into the chamber 310 via the flow line 335 and / or via the flow line 354 to the third flow controller 357. The third flow controller 357 may be configured to direct the gas through the optional flow restrictor 358 and through the flow line 359 to the second exhaust 370 (the preflow gas path described in more detail below). Defined) and / or directed through the flow line 331 through an optional flow restrictor 356 to the chamber 310, which may be in communication with the flow line 335.

  During operation, parallel flow lines 325, 335 provide a series of flow controllers and optional flow control units (flow controllers 340, 345, 347, 350, 355, 357 and optional flow restrictors) that independently pass gas to chamber 310. 346, 356, etc.), and quick gas exchange is possible. The flow lines 325, 335 may also be capable of delivering gas independently and / or directly to the chamber 310 at high speeds to eliminate gas delays observed through any flow restrictors 346, 356. In another embodiment, the flow lines 325, 335 meet prior to entry into the chamber 310. In the high-speed gas exchanger 300, many gas delivery methods and configurations are conceivable. In one embodiment, the first gas (or combination of gases) is delivered directly to the chamber 310 (eg, through flow lines 341, 342, 325) and the second gas (or combination of gases) is delivered to the flow line 354, Via 352, 351, the option of pulsing through the flow restrictor 356 of the flow line 331 to control delivery to the chamber 310 is obtained. Each valve of the high-speed gas exchanger 300 may include a check valve for preventing back diffusion of gas sent through the flow line. The flow controllers 340 and 350 can direct the gas through the flow lines 343 and 353, and these flow lines communicate with the first discharge part 360. The flow controllers 347 and 357 can direct the gas through the flow lines 349 and 359, and these flow lines communicate with the second discharge unit 370.

  In one embodiment, the high-speed gas exchanger 300 includes an optional flow line 386 that is in communication with either or both of the flow lines 341, 351. The flow line 386 can include an optional flow controller 384 and / or an optional flow restrictor 382. The flow line 386 may be capable of directing gas to the exhaust 380 to discard gas from all flow lines, defining a high speed exhaust path that will be described in more detail below. The exhausts 360, 370, 380 may include a vacuum environment, and the gas is directed toward the vacuum environment.

  In one embodiment, the high-speed gas exchanger 300 can be connected to an optional gas panel 390 to provide a gas supply source 392 (such as purge gas) to the chamber 310 via the flow line 395, In combination with the embodiments described herein, the flow line 335 is in communication. The gas panel 390 can operate as a quick disposal valve to remove residual gas in the chamber 310 and prevent residual gas from being mixed into the process gas mixture prior to transition between process gas mixtures. The gas panel 390 may also provide a high-speed direct line to the chamber 310 for supplying processing gas with gas from either or both of the first and second gas panels during the etching cycle. The flow line 395 can include a flow controller and / or restrictor for controlling the flow from the gas 390 to the chamber 310. The gas supply 392 may be purgeable of the residual gas mixture remaining in the chamber 310 and the flow line. In one embodiment, one or more of the flow controllers are actuated to an open position and the residual gas mixture is routed to one or more of the exhausts 360, 370, 380 through either or both of the flow lines 325, 335, Purge is performed using the gas supply source 392 supplied from the gas panel 390. Similar gas panel equipment can be installed in communication with the flow line 325.

  In one embodiment, the substrate is placed in chamber 300 to form a profile in the substrate during the process. This process may include one or more steps (etching step, deposition step, etc.), and the profile is formed by repeating these steps alternately or sequentially in various orders. A first gas mixture containing one or more gases supplied from a gas supply source 322 of the first gas panel 320 is passed from the first gas panel 320 to the chamber 310 via the first and second flow controllers 340 and 354. During one or more of the process steps through the flow lines 341, 342, 325 and / or via the first, second and third flow controllers 340, 345, 347 and through the flow lines 341, 342, 344, 321, 325 Can be supplied to. The second gas mixture containing one or more gases supplied from the gas supply source 332 of the second gas panel 330 is passed from the second gas panel 330 to the chamber 310 via the first and second flow controllers 350 and 355. One or more of the process steps through the flow lines 351, 352, 354, 321, 335 and / or via the first, second, third flow controllers 350, 355, 357 It can be supplied in the middle. The first and second gas mixtures can be quickly switched into the chamber 310 when switching process steps. Direction from each flow line 325, 335 to outlet 360, 370, 380 as the first and second gas mixtures are switched between process switches and while other gas mixtures are being supplied to chamber 310. It can also be attached. In addition, the composition of the gas mixture can be changed during the switching process step and another gas mixture can be supplied to the chamber during one process step. The first and second gas mixtures can be simultaneously supplied to the chamber 310 during certain process steps. The flow controller can provide a flow path to the unconstrained chamber 310.

  In one embodiment, the fast gas exchange system uses one or more valves while processing the substrate in the chamber when switching from the first etching step to the second etching step and / or the deposition step ( Combinations of flow controllers, etc. For example, a three-way valve, which may include a pneumatic actuator that provides a quick responsive action), allows continuous and rapid switching of the gas mixture within the chamber. For example, during the deposition step, a first gas mixture is supplied to the chamber while a second gas mixture is delivered to the chamber in preparation for introduction into the chamber during the etching step following the deposition step. The duration of each step may be less than 1 second. For example, the deposition step lasts about 0.5 seconds, the etching step lasts about 0.75 seconds, and these steps are repeated continuously and alternately while feeding during the steps representative of the respective gas mixture. Is processed in the chamber. By attaching one or more sensors to the valve, the performance of the gas mixture supplied to the chamber can be monitored.

  As shown in FIG. 4A, when the trench 400 is etched into one or more layers 410, 420, 430 of the substrate, a number of scallops 415 are formed along the sidewalls of the trench. Scallop 415 may appear as a series of peaks 411 and valleys 412 along the sidewall. The scallop measurement 413 may include a measurement from the depth of the valley 412, ie, the bottom center of the valley 412, as shown in FIG. 4B. In one embodiment, the length of the valley 412 (ie, the vertical distance from the tip of one peak to the tip of an adjacent peak) and the number of peaks 411 and valleys 412 are utilized with the fast gas exchanger 200 or 300 with the reactor 100. Increase or decrease by doing. As the scallop measurement 413 increases, the sidewall roughness increases. In one example, a high speed gas exchanger 200 or 300 is utilized to form a trench with an etch rate of about 10 micrometers / minute and a scallop measurement 413 of about 0.1 micrometers. The scallop measurement 413 is maintained within reasonable tolerances along the sidewalls while forming the trench across the substrate, for example, the scallop measurement 413 is about 0.1 micrometers or more at the top of the trench, Of about 0.025 micrometers or less at the bottom. In one embodiment, the trench is formed with a scallop measurement 413 of about 0.1 micrometers at an etch rate of about 20 micrometers / minute. In one embodiment, the trench is formed at an etch rate of about 10 micrometers / min with a deposition step having a duration of about 1 second to about 2 seconds and an etch step having a duration of about 2 seconds to about 4 seconds. The etching step can include a first etching step and a second etching step.

  By using the high-speed gas exchanger 200 or 300, the amount of photoresist remaining on the trench profile after etching can be increased. In forming a deeper trench profile, the resist selectivity can be improved by the high-speed gas exchanger 200 or 300.

  A higher etching performance is obtained by the high-speed gas exchanger 200 or 300. The high speed gas exchanger 200 or 300 provides the following advantages. That is, gas delay from the mass flow controller to the chamber is reduced, mixing of multiple gas types is eliminated, gas exchange time is reduced, gas delivery delays between process steps are reduced, and gas types can be overlapped Gas delivery across multiple zones, and remote and local gas panel locations. These advantages result in higher overall etch rates, reduced trench sidewall roughness, and increased ability to control the trench profile. The high-speed gas exchanger 200 or 300 can be used together with an etching system (TMGM system, Bosch system, etc.) employing a multi-step process.

  In one embodiment, a method of etching a substrate in a chamber supplies a first gas from a first gas panel to the chamber during the deposition step, and a second gas from the second gas panel is supplied to the first etching step and the first gas. Supplying the chamber during the second etching step, applying a first bias power to the substrate during the first etching step, and applying a second bias power during the second etching step, the first bias power being the second Greater than bias power.

  In one embodiment, optionally multiple layers (such as oxides, metals and / or deposited protective polymer films, etc. The protective polymer film contains at least one polymer, copolymer, oligomer, derivative or combination thereof (hard A method is provided for etching a substrate, such as a silicon substrate, on which a mask, resist mask, etc.) is deposited. The method includes an etching cycle having a deposition step, a first etching step, and a second etching step. The process can include employing a high bias power and low pressure during the first etch step and employing a low bias power and high pressure during the second etch step to form a trench in the substrate. Is used for etching multiple layers (such as oxides, metals and / or polymer films), and low bias power is used for etching substrates (such as silicon substrates). This process provides improved resist selectivity and reduces trench sidewall roughness.

  In one example, an etch step under a conventional silicon etch system spends about 40% of that time in the isotropic penetration of silicon and removal of the surface polymer prior to etching. Bias power is required to penetrate the polymer layer, but silicon etching is exothermic and consequently does not require bias power. A deposition step of about 5 seconds can be utilized with an etching step of about 10 seconds to obtain optimum critical dimensions and etch rates. If the bias power is ON for the entire 10 seconds of the etch step and the polymer surface is etched after about 4 seconds, etching the silicon for the remaining about 6 seconds with bias power reduces resist selectivity and The side wall roughness is increased. In this same example, embodiments of the present invention provide an etch step comprising a first etch step that includes a low voltage / high bias power of about 4 seconds followed by a second etch that includes a high voltage / remaining low bias power of about 6 seconds. This problem is addressed by dividing it into steps, which increases resist selectivity. In one embodiment, the deposition step time is about 1 second to about 20 seconds and the etching step time is within about 2 seconds to about 30 seconds.

  FIG. 5A illustrates a conventional etching cycle 500 having a step overlap 520 in switching between steps for etching a silicon substrate, including a deposition step 510 of about 5 seconds and an etching step 530 of about 10 seconds. Show. FIG. 5B illustrates an etching cycle 550 according to one embodiment of the present invention performed on the same substrate as conventional cycle 500. FIG. 5B shows depositing a thin film polymer layer for about 3 seconds during the deposition step 560, etching the polymer layer for about 3 seconds during the first etching step 570, and about 5 seconds during the second etching step 580. A method of etching a silicon substrate including etching a silicon layer, wherein a first bias frequency is applied to the silicon substrate during the first step, a second bias frequency is applied to the silicon substrate during the second etching step, The 2 bias frequency is smaller than the first frequency. As shown, the etch cycle 550 can be about 4 seconds faster than the conventional etch cycle 500, forming a substantially similar trench profile. By using the high-speed gas exchanger 200 or 300, it is possible to eliminate gas duplication when switching from the deposition step to the etching step.

  In one embodiment, the method includes increasing resist selectivity by using bias power during the first etching step of the etching cycle and using zero bias power during the second etching step.

  In one embodiment, the method etches the metal and oxide layers with a bias power having a frequency of about 2 MHz during the first etching step and then switches to a bias power with a frequency of about 400 kHz during the second etching step. Etching. The method may further include multiple power bias power matching.

  FIG. 6A shows an etching feature or profile (such as trench profile 600) formed using conventional methods. FIG. 6B shows a trench profile 650 formed using a method according to one embodiment of the invention. As shown, trench profile 600 formed using conventional methods has a higher degree of roughness along the sidewalls, for example, scallop measurements are approximately about 6.7 micrometers / minute etch rate. Greater than 2 micrometers. The trench profile 650 formed using the fast gas exchanger 200 or 300 and the reactor 100 reduces sidewall roughness and provides a smoother profile, for example, scallop measurements are about 5.8 micrometers / etch etch rate. Less than about 1.5 micrometers in minutes. The trench profile 650 may also include a smooth and rounded etch front. In addition, this two-step etching process can be utilized to further achieve smaller scallop measurements.

  In one embodiment, the etching cycle further includes a removal process that includes removal of the remaining photoresist mask or protective polymer film on the etched material surface and / or along the trench surface. In one example, the removal process is completed using an oxygen-containing plasma for silicon-based substrates. This removal process can be performed after the trench profile is etched using embodiments of the present invention.

  In one embodiment, the etching cycle further includes an additional etching or removal process (sometimes referred to as a sidewall smoothing process) that reduces the surface roughness (eg, occurrence of scallops) caused by the etching. Further smoothing along the trench profile. The sidewall smoothing process can be performed after the removal process described above. With the sidewall smoothing process, a reactive plasma milling process can be used to further reduce the depth of the scallop formed on the sidewall surface of the etched trench. An exemplary embodiment of the removal process and reactive plasma milling process was continued on August 27, 2008 in “Post Etch Reactive Plasma Milling to Smooth Through Substrate Via Sidewalls and Other Deep Etch”. Which is disclosed in U.S. Patent Application, which is hereby incorporated by reference in its entirety.

In one embodiment, a reactive plasma milling process is used to expose a trench profile scalloped surface to a reactive plasma formed from a plasma source gas. This gas includes reactants including but not limited to SF ₆ , NF ₃ , CF ₄ , CHF ₃ , CIF ₃ , BrF ₃ , IF ₃ or derivatives thereof, and the reactants are material at the surface of the trench profile. React with. The plasma source gas may contain an inert gas, which does not react with the trench profile, but acts as an impact force that can impact the trench profile, decomposing the material and removing the material from the scallop To do. In one embodiment, after the residual polymeric material is removed from the trench profile of the substrate, the trench profile is treated with a reactive plasma generated from a plasma source gas while applying bias power to the substrate. The bias power may be pulsed, that is, the RF power can be switched on and off during substrate processing. The reactive plasma milling process uses the embodiments of the present invention described herein, such as plasma source gas composition, substrate temperature, pressure in the processing chamber, high frequency power with respect to bias power and / or source power, etc. Configurable by adjusting process variables.

  In one embodiment, the preflow gas path is installed in a chamber (such as chamber 25 of reactor 100) using a gas delivery system such as fast gas exchange systems 200 and 300. The preflow gas path may be a connection from the gas delivery source through the valve to a vacuum environment separate from the chamber. Before sending the gas to the chamber, it is possible to flow the gas through the preflow gas path to stabilize the flow before the gas is requested. In addition, since any flow control device (such as a flow controller) can send its emissions to the preflow gas path, a portion of the gas flow can be stabilized before sending the gas flow to the chamber. .

  In one embodiment, a high speed exhaust path is installed from a chamber (such as chamber 25 of reactor 100) to a discharge or waste section using a gas delivery system (such as high speed gas exchange systems 200 and 300). The fast exhaust path may be a connection from the gas delivery source and chamber delivery path to the chamber, via a valve from the chamber to another vacuum environment. One or more valves can be used for each chamber delivery path connection, because a high speed exhaust path can be connected at multiple locations, between any two flow control devices and / or flow control sections. There is also at least one connection. If a change in gas in the chamber is required, the valve to the vacuum environment is opened and excess gas is removed from the chamber delivery path.

  In one embodiment, the gas delivery system (fast gas exchange systems 200 and 300 over time) so that the actual gas flow into the chamber (such as chamber 25 of reactor 100) reaches the desired state as quickly as possible. Etc.) is provided to control gas flow. If there is no gas in the chamber delivery path, the gas delivery system can increase the respective flow rate of the desired gas so that the gas delivery system reaches equilibrium in the shortest possible time. As the gas flow into the chamber approaches the desired chemical mixture and flow rate, the gas flow rate through the gas delivery system is reduced to the desired level in such a manner that the desired flow rate into the chamber is maintained. If the gas delivery system is filled with gas from a previous process, the flow rate through the gas delivery system can be changed (decreasing or increasing depending on the desired effect), which allows the desired flow into the chamber Reach the desired value as quickly as possible. As the gas flow to the chamber approaches the desired chemical mixture and flow rate, the gas flow is adjusted to the desired flow rate in such a manner that the desired flow rate to the chamber is maintained.

  In one embodiment, flow control of the high speed exhaust path is provided using a variable flow control, a fixed flow control, or a series of selective fixed flow control. If the chemical mixture delivered to the chamber is changed but the flow rate at the time of change needs to be controlled, one or more valves between the chamber delivery path and the high speed exhaust path are throttled to control the exhaust rate. Can do. In some cases, the desired chemical mixture and flow rate to the chamber by squeezing a valve along the chamber delivery path so that a portion of the gas is evacuated to the high speed exhaust path and a portion is delivered to the chamber. Can be achieved more quickly.

  In one embodiment, gas delivery to the chamber continues uninterrupted utilizing residual gas in the chamber delivery path when changing from one chemical mixture and flow rate to another chemical mixture and flow rate. By closing one or more valves in the chamber delivery path, gas downstream of the valve continues to flow into the chamber and gas upstream of the valve is routed elsewhere. The gas flow upstream of the closed valve does not reach the chamber while the valve is closed. In this way, the chamber continues to operate uninterrupted by the gas downstream of the valve (residual gas), and the gas upstream of the valve is changed to the next desired chemical mixture and flow rate. Before all the gas downstream of the valve in the chamber delivery path has been sent into the chamber, the valve is opened to introduce the next desired chemical mixture into the chamber at the desired flow rate.

  In one embodiment, one or more valves in the chamber delivery path, preflow path, and fast exhaust path are arranged in a certain order. By actuating the valves in chronological order, the desired chemical mixture can be delivered to the chamber at the desired timing at the desired flow rate. Before a new chemical mixture and flow rate is required in the chamber, the valve can be actuated to start a new chemical mixture flow through the chamber delivery path at the new flow rate. At the same time, the valves are actuated towards the chamber delivery path, the preflow path and the high speed exhaust path to stabilize the flow of new chemical mixture and flow rate through the chamber delivery path, and the delivery of chemicals into the chamber within the chamber delivery path. Continue from the residual gas and remove residual chemicals from hidden parts of the chamber delivery path. Chemical switching can occur in the shortest time at the location closest to the chemical delivery source. Utilizing a timed switch of a series of valves spaced from the chemical delivery source to the chamber along the chamber delivery path for the fast exhaust path, preflow path, and chamber delivery path, a new chemical mixture at a new flow rate, The chamber can be delivered dimensionally with a time as close as possible to the required time.

  In one embodiment, feedback of chemical delivery in the chamber delivery path, fast exhaust path, and preflow path is utilized. The chemical mixture and flow rate can be measured in various paths with pressure sensors, flow sensors, chemical sensors and / or other sensors that monitor conditions in the path. When changing the chemical mixture and flow rate using any of the methods described above, these sensor measurements can be used to improve control of chemical delivery and valve settings (ie, open, closed, It is possible to determine the proportional state). It is possible to measure and adjust the chemical mixture transition and steady state performance and flow rate using sensors to control the timing used to change the valve operating settings or states.

  In one embodiment, feedback of chemical delivery into the chamber is utilized. Pressure sensors, optical sensors, and other sensors that provide feedback from the chamber can be used to determine the actual chemical mixture and flow rate into the chamber. When changing the chemical mixture and flow rate to the chamber, measurements can be used to improve control of chemical delivery and to determine valve settings. Measurements can also be used to measure and determine chemical mixture migration and steady state performance and flow rates.

  In one embodiment, predictive flow control methods are used to minimize gas transition times. This method allows the chemical mixture to flow at a flow rate other than the desired flow rate and then converges to the desired flow rate to achieve the equilibrium gas line pressure and thus the actual desired flow into the chamber in the shortest possible time. May be included.

  In one embodiment, a method for predictively arranging valves in a certain order using a model of a flow system is provided. This method consists of flow rate, gas delivery system capacity, gas delivery line capacity, chamber shower head capacity, gas delivery system control, chamber shower head control, equilibrium pressure in the flow of gas delivery system, valve System valves are arranged in a certain order using operating time, chamber pressure, foreline pressure and / or gas species to provide optimal gas delivery to the processing chamber for a particular etching / deposition process. Can be included.

  In one embodiment, since the system has one or more gas delivery systems, at least one gas delivery system is dedicated to specific process conditions. A dedicated gas delivery system, and thus the system, may require a smaller number of chemicals. A dedicated gas delivery system can be configured with a small group of flow controllers required for the entire processing of the substrate, which can greatly reduce costs and reduce system complexity.

  7A-C illustrate a gas migration process using the systems 100, 200, and 300 described herein. The delivery of the first gas 710 to the chamber 750 is stopped, and the delivery of the second gas 720 is started. As the second gas 720 flows into the line 760, the tip of the gas flow mixes with the residue of the first gas 710 in the line 760. The second gas 720 pushes the residual first gas 710 through the line 760 and into the chamber 750. In one embodiment, the delay between the gas switch command being issued and the second gas 720 being delivered to the chamber 750 is between about 8 seconds and about 25 seconds. The gas transfer timing quickly provides optimal gas delivery for a particular etch / deposition process into the chamber 750 by changing the gas flow using the measurement and predictive control methods described herein. It is possible to improve it.

  8A-C illustrate a gas migration process using the systems 100, 200, and 300 described herein. Delivery of the first gas 810 to the chamber 850 (via line 860) is stopped by closing the valve 865 and opening the valve 875, and the first gas 810 is exhausted using, for example, the foreline 870. The At the same time, when the first gas 810 is shut off, delivery of the second gas 820 through the line 860 starts. As the second gas 820 flows through the line 860, the tip of the gas flow mixes with the residue of the first gas 810 in the line 870 and escapes. The second gas 820 pushes the remaining first gas 810 through the line 860 and into the foreline 870. The chamber 850 can continue to operate using another first gas 810 residue in the chamber. Valve 875 can then be actuated to the closed position and valve 865 can be actuated to the open position to deliver a non-contaminated second gas 820 stream to chamber 850. Gas transition timing can occur within about 5 to about 10 seconds. Since line 860 was evacuated during disposal of the first gas 810, about 10 seconds to about 30 seconds from the gas transition command is required to obtain a stable flow of the second gas 820.

  9A-D illustrate a gas migration process using the systems 100, 200, and 300 described herein. This gas migration process may be the process described above for FIGS. 8A-C with respect to delivery of the first gas 910 to the chamber 950 through line 960. Valve 965 is in the open position and all other valves 967, 975, 985, 987 are in the closed position. Pre-filling the line 980 with the second gas 920 stabilizes the flow to the chamber 950 because the required amount of the second gas 920 is already in the line 980 when the line 980 is connected to the chamber 950. In one embodiment, a single transition gas is used in line 980. The valve 975 is then actuated to the open position, the other valves are actuated or maintained in the closed position, and process gas 930 (such as residual first gas 910) is transferred from the chamber 950 to the exhaust, for example, the foreline 970. To discharge through. A flow controller can be used to stabilize the flow through the foreline 970 before gas transfer. Valves 985 and 967 can then be actuated to the open position and the other valves can be actuated or maintained in the closed position. The second gas 920 can be delivered to the chamber 950 via line 980 and the first gas 910 can be exhausted using the foreline 970. Gas migration can depend on valve timing. The gas transition has a relatively clean exponential rise and decay. Fully stabilizing the flow of the second gas 920 may require a gas transition time of about 2 seconds to about 5 seconds from the gas transition command. The exact transition time can be calculated using the direct measurement and / or predictive control method described above based on information obtained from one or more sensors 990.

  FIG. 10 illustrates a gas delivery system 1000 that may be utilized with the embodiments described herein. The system 1000 includes a chamber connected housing 1040 for storing and positioning one or more switching valves 1065, 1075, 1085 as close as possible to the chamber and / or a showerhead connected to the chamber 1050. (Such as a grounding enclosure). The switching valves 1065, 1075, 1085 can be stored in a grounded enclosure within the gas source assembly. In one embodiment, line 1080 is dedicated to a particular gas migration process that requires only one type of gas.

  Accordingly, a gas delivery system having a high-speed exhaust path advantageously allows a process gas to be supplied from the gas delivery system to the processing system with a stable gas flow and minimal fluctuations. A high-speed exhaust path is utilized to verify and / or calibrate the gas flow from the gas delivery system in another manner and to better control the gas flow supplied to the processing chamber.

  While the above is directed to embodiments of the invention, other and further embodiments of the invention may be made without departing from the basic scope of the invention and the scope of the invention is subject to the following patents: It is determined based on the scope of claims.

Claims (3)

Depositing a polymer film on at least one layer comprising a metal disposed on a substrate during the deposition process;
Etching an opening in the at least one layer disposed on the substrate during a first etching process;
Forming a profile in the at least one layer disposed on the substrate by etching the substrate during a second etching process;
A first bias power is applied to the substrate during a first etching process that etches the at least one layer, a second bias power is applied to the substrate during a second etching process that etches the substrate, and the first bias power is A method of etching a substrate in a chamber greater than 2 bias power.   The method of claim 1, wherein the substrate comprises a plurality of layers comprising at least one of silicon and oxide.   The method of claim 1, further comprising pulsing at least one of the first bias power and the second bias power.

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