Selective etching process using hydrofluoric acid and ozone gas

Abstract

A method for etching a titanium-containing layer on a workpiece is provided. In one example, the method includes placing the workpiece on a workpiece support in a processing chamber. The workpiece includes a first layer and a second layer. The first layer is a titanium-containing layer. The method includes introducing a process gas into the processing chamber. The process gas includes an ozone gas and a fluorine-containing gas. The method includes exposing the first layer and the second layer on the workpiece to the process gas to at least partially etch the first layer at a greater etch rate relative to the second layer.

Description

[0001] This application is a divisional application of Chinese application entitled “Selective Etching Process Using Hydrofluoric Acid and Ozone Gas”, filed on October 16, 2020, with application number 202080087727.1. Technical Field

[0002] This disclosure generally relates to the processing of workpieces (e.g., semiconductor workpieces). Background Technology

[0003] Semiconductor fabrication can involve the deposition and removal of different material layers on a substrate. As the critical dimensions of semiconductor devices continue to shrink, device size and material thickness in semiconductor fabrication are constantly decreasing. At advanced device nodes, material removal with high selectivity relative to other materials may become increasingly important for semiconductor device performance. For example, in some structures, etching of titanium and / or titanium nitride relative to other materials may be particularly important because such etching is widely used in semiconductor devices. Summary of the Invention

[0004] Aspects and advantages of embodiments of this disclosure will be set forth in part in the description which follows, or may be learned from the description or by practice of the embodiments.

[0005] One example aspect of this disclosure relates to a method for machining a workpiece. The method includes placing the workpiece on a workpiece support within a processing chamber. The workpiece includes a first layer and a second layer. The first layer is a titanium-containing layer. The method includes introducing process gases into the processing chamber. The process gases include ozone gas and a fluorine-containing gas. The method includes exposing the first and second layers on the workpiece to the process gases to at least partially etch the first layer relative to the second layer at a greater etching rate.

[0006] Other exemplary aspects of this disclosure relate to systems, methods, and apparatus for processing workpieces.

[0007] These and other features, aspects, and advantages of the various embodiments will be better understood by referring to the following description and the appended claims. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the present disclosure and, together with the specification, serve to explain the relevant principles. Attached Figure Description

[0008] The specification describes in detail embodiments for those skilled in the art, with reference to the accompanying drawings, in which:

[0009] Figure 1 An overview of an example etching process according to an example embodiment of the present disclosure is provided;

[0010] Figure 2A flowchart depicting an example method according to an example embodiment of the present disclosure is shown;

[0011] Figure 3 An example processing chamber configured to perform an etching process according to an example embodiment of the present disclosure is depicted;

[0012] Figure 4 An example plasma processing apparatus configured to perform a surface treatment process according to an example embodiment of the present disclosure is depicted;

[0013] Figure 5 An example injection of ozone gas and / or HF gas at a separation grid is depicted according to an exemplary embodiment of the present disclosure;

[0014] Figure 6 A flowchart depicting an example method according to an example embodiment of the present disclosure is shown;

[0015] Figure 7 Example processing results according to example embodiments of this disclosure are depicted; and

[0016] Figure 8 An example processing result according to an example embodiment of the present disclosure is depicted. Detailed Implementation

[0017] Reference will now be made in detail to embodiments, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explaining the embodiments and is not intended to limit the scope of this disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope or spirit of this disclosure. For example, features shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, aspects of this disclosure are intended to cover such modifications and variations.

[0018] An exemplary aspect of this disclosure relates to etching processes for etching titanium and / or titanium nitride relative to other materials on a workpiece, such as a semiconductor workpiece, like a semiconductor wafer. As semiconductor device manufacturing processes become increasingly complex and device dimensions continue to shrink, the requirements for etching selectivity in semiconductor manufacturing processes are becoming increasingly stringent. In some applications, such as hard mask removal processes, it may be necessary to remove titanium and / or titanium nitride from the workpiece with high selectivity relative to other materials, such as silicon, silicon germanium, silicon nitride, silicon dioxide, tungsten, tantalum nitride, metal layers, etc. Plasma-based processing can expose the workpiece to fluorine radicals to etch titanium and / or titanium nitride on a semiconductor workpiece. However, the use of fluorine radicals is subject to low selectivity relative to certain materials, such as silicon and silicon germanium.

[0019] According to exemplary aspects of this disclosure, systems and methods for processing semiconductor workpieces can provide selective etching of titanium and / or titanium nitride layers on the workpiece relative to other materials by exposing the workpiece to a co-current flow of hydrofluoric acid (HF) gas and ozone gas. For example, in some embodiments, the process of selectively etching titanium and / or titanium nitride layers relative to other layers on the workpiece may include exposing the workpiece to process gases in a processing chamber. The process gases may include both HF gas and ozone gas. In some embodiments, the process gases may include HF vapor. In some embodiments, the process gases may include oxygen (O2) and / or a carrier gas (e.g., oxygen, nitrogen, helium, argon, neon, or other inert gases). The active components of the process gases (e.g., HF gas / vapor and ozone gas) may flow into the processing chamber simultaneously.

[0020] In some embodiments, HF gas (e.g., HF vapor) can be directly supplied to the processing chamber from an HF source (e.g., an HF bottle). Furthermore, and / or alternatively, HF gas can be formed from a remote plasma source using a remote plasma source. For example, inductively coupled plasma can be generated from process gases in a remote plasma chamber (e.g., separated from the processing chamber by a separation grid). The process gases in the plasma chamber may include F-containing gases (e.g., CF4, NF3, CF2). x H y (etc.) and H-containing gases (e.g., H2, CH4, C2H8, etc.). HF radicals generated in the plasma can be transported downstream from the plasma chamber to the processing chamber to expose the workpiece.

[0021] In some embodiments, ozone gas can be delivered directly to the processing chamber from an ozone gas source (e.g., an ozone generator). The ozone gas may include O3 and accompanying O2 gas. The concentration of O3 in the ozone gas may range from about 1% to about 50% by volume.

[0022] According to an exemplary aspect of this disclosure, ozone gas and HF gas can flow concurrently into a processing chamber to expose the workpiece for selective etching of titanium and / or titanium nitride relative to other materials on the workpiece. Other materials may include, for example, silicon, polysilicon, silicon germanium, silicon nitride, silicon dioxide, metals (e.g., tungsten), tantalum nitride, low-k materials, etc. In some embodiments, the concurrent exposure of the workpiece to HF gas and ozone gas can result in a high etching rate for titanium nitride and / or titanium, such as about 200 Å / min or higher. The etch cross-sectional profile of titanium and / or titanium nitride can be isotropic. This process can at least partially etch titanium and / or titanium nitride at a greater etching rate relative to other materials on the workpiece.

[0023] The exemplary aspects of this disclosure can provide numerous technical effects and benefits. For example, systems and methods according to the exemplary aspects of this disclosure can provide etching of titanium and / or titanium nitride with high selectivity to materials including silicon and silicon germanium. The method can be implemented as an all-dry process with high etching rates for titanium and / or titanium nitride. In some embodiments, process gases can be introduced directly into the processing chamber without requiring a remote plasma source.

[0024] In some embodiments, HF gas and ozone gas can be sequentially supplied to the processing chamber in a cyclic manner to expose the workpiece. The first portion of each cycle may deliver HF gas (plus a carrier gas). The second portion of each cycle may deliver ozone gas. These cycles can be repeated. The cyclic process can etch titanium nitride and / or titanium using atomic layer etching (ALE) to remove a small amount of titanium nitride and / or titanium (e.g., about 1 to about 5 angstroms) in each cycle. This allows for precise control of the etching process by controlling the number of cycles.

[0025] This disclosure provides numerous technical effects and benefits. For example, exposing a workpiece to a co-current process gas, including HF and ozone gas, can provide highly selective etching of titanium and / or titanium nitride relative to other materials on the workpiece. The etching process according to the example aspect can be an all-dry etching process with a high etching rate (e.g., about 200 Å / min or greater). Furthermore, the process can be carried out in a processing chamber with or without a remote plasma source, thereby increasing the versatility of implementing etching processes in semiconductor manufacturing equipment.

[0026] For illustrative and discussion purposes, aspects of this disclosure are discussed with reference to the terms "workpiece" or "wafer." Those skilled in the art who use the disclosure provided herein will understand that exemplary aspects of this disclosure can be used in conjunction with any semiconductor substrate or other suitable substrate. Furthermore, the term "about" used in conjunction with numerical values ​​means less than ten percent (10%) of the stated value. "Substrate" refers to any structure that can be used to support a workpiece. Low-k dielectric materials may have a dielectric constant less than about 3.0, for example less than about 2.5, for example less than about 2.2. "Ozone gas" refers to any gas containing O3. Ozone gas may be a mixture of O3 and O2.

[0027] Figure 1 An overview of an example process 110 for etching titanium and / or titanium nitride on a workpiece 60 according to an exemplary embodiment of this disclosure is described. As shown, the workpiece 60 may include a substrate layer 62 (e.g., a silicon substrate layer) and a titanium-containing layer 64 (e.g., titanium and / or titanium nitride). Selective etching of the titanium-containing layer may be desirable relative to other layers on the workpiece 60, such as the substrate layer 62. Figure 1As shown, etching process 110 may include exposing a workpiece 60, comprising a titanium-containing layer 64 and a substrate layer, to a process gas comprising HF gas (e.g., a gas containing HF vapor) and ozone gas. In some embodiments, the process gas may include a carrier gas, such as nitrogen or an inert gas (e.g., argon, helium, etc.). Exposing the workpiece 60 to the process gas may etch the titanium-containing layer 64 at an etching amount 65.

[0028] The following provides example process parameters for etching process 110:

[0029] Processing temperature of workpiece: approximately 100°C to approximately 500°C

[0030] Process pressure: Approximately 100mT to approximately 100T

[0031] Process gases: HF gas, ozone gas, and carrier gas

[0032] Carrier gases: N2, He, Ne, Xe, etc.

[0033] Total process gas flow rate: approximately 100 sccm to approximately 100 slm.

[0034] HF gas flow rate: 10 sccm to approximately 10 slm

[0035] Ozone gas flow rate: 10 sccm to approximately 10 slm

[0036] O3 concentration in ozone gas: approximately 1% to approximately 50% by volume.

[0037] Process cycle: Approximately 5 seconds to approximately 600 seconds

[0038] Figure 2 A flowchart of an example method (200) according to an example aspect of this disclosure is depicted. The method (200) can be implemented in a processing apparatus, such as any processing apparatus described herein. However, as will be discussed in detail below, the method according to an example aspect of this disclosure can be implemented using other methods without departing from the scope of this disclosure. For purposes of illustration and discussion, Figure 2 The steps are described in a specific order. Those skilled in the art who use the disclosure provided herein will understand that the individual steps of any method described herein can be omitted, extended, performed concurrently, rearranged, and / or modified in various ways without departing from the scope of this disclosure. Furthermore, various additional steps (not shown) may be performed without departing from the scope of this disclosure.

[0039] At (202), the method may include placing a workpiece on a workpiece support (e.g., a base) within a processing chamber. The workpiece may be a semiconductor wafer. In some embodiments, the workpiece may include a titanium layer and / or a titanium nitride layer. The workpiece may include other material layers, including one or more of silicon, polycrystalline silicon, silicon-germanium, silicon nitride, silicon dioxide, metals (e.g., tungsten), tantalum nitride, low-k materials, etc.

[0040] At (204), the method may include heating the workpiece to a process temperature. The process temperature may be in the range of about 100°C to about 500°C, for example, about 150°C to about 500°C.

[0041] At (206), the method may include introducing a process gas into a chamber within the processing chamber. According to an exemplary aspect of this disclosure, the process gas may include a co-flow of ozone gas and HF gas. In some embodiments, the HF gas may include HF vapor. In some applications, the process gas may additionally include a carrier gas, such as nitrogen or an inert gas. The total flow rate of the process gas may range from about 100 sccm to about 100 slm, for example, from about 100 sccm to about 10 slm, for example, from about 500 sccm to about 10 slm. The flow rate of the HF gas (e.g., including HF vapor) may range from about 10 sccm to about 10 slm, for example, from about 10 sccm to about 1 slm, for example, from about 50 sccm to about 1 slm. The flow rate of the ozone gas may range from about 10 sccm to about 10 slm, for example, from about 10 sccm to about 1 slm, for example, from about 50 sccm to about 1 slm. The O3 concentration in the ozone gas may range from about 1% to about 50%.

[0042] exist Figure 3 At (208), the method may include exposing a titanium and / or titanium nitride layer on a workpiece to a co-current process gas comprising ozone gas and HF gas for a process cycle. The process cycle is the time the gas is exposed to the workpiece. In some embodiments, the process cycle may range from about 5 seconds to about 600 seconds. In some embodiments, the process cycle may range from about 30 seconds to about 90 seconds. After the process cycle, the process gas may be withdrawn from the processing chamber.

[0043] At (210), the method may include removing a workpiece from the processing chamber. The processing chamber may then be processed and / or cleaned, and the next workpiece may be placed in the processing chamber.

[0044] Figure 3 An example processing chamber 250 is depicted that can be used to implement the method (200) according to an example aspect of this disclosure. The processing chamber 250 may include an internal volume 255 configured to receive a workpiece 216. The workpiece 216 may be supported on a workpiece support 254.

[0045] The workpiece can be heated using a temperature control system 258 associated with the workpiece support 254. The temperature control system 258 may include a heating element (e.g., a resistance heating element) disposed on the workpiece support 254. In some embodiments, the temperature control system 258 may include one or more fluid channels operable to circulate fluid through the workpiece support 254 to heat or cool the workpiece 216. Other suitable heat sources may be used without departing from the scope of this disclosure, such as lamp heat sources, lasers, plasma heat sources, etc.

[0046] In some embodiments, the control system can regulate the temperature of the workpiece to a temperature setpoint. For example, one or more sensors (e.g., pyrometers, temperature sensors, etc.) can be used to provide signals indicating the workpiece temperature during the surface treatment process. The temperature regulation system 258 can heat and / or cool the workpiece based on the signals indicating the workpiece temperature to regulate the workpiece temperature to the temperature setpoint.

[0047] Gas inlet 252 can be used to introduce process gas into the interior 255 of the processing chamber. Other suitable methods and / or apparatus can be used to introduce process gas into the processing chamber without departing from the scope of this disclosure. For example, process gas can be introduced via a nozzle or other suitable gas injection source. As described above, the process gas may include a co-flow of ozone gas and HF gas (e.g., including HF vapor). In some embodiments, the process gas may additionally include a carrier gas, such as nitrogen or an inert gas. The total process gas flow rate can be in the range of about 100 sccm to about 100 slm, for example, about 100 sccm to about 10 slm, for example, about 500 sccm to about 10 slm. The gas flow rate of HF gas (e.g., including HF vapor) can be in the range of about 10 sccm to about 10 slm, for example, about 10 sccm to about 1 slm, for example, about 50 sccm to about 1 slm. The gas flow rate of ozone gas can be in the range of about 10 sccm to about 10 slm, for example, about 10 sccm to about 1 slm, for example, about 50 sccm to about 1 slm.

[0048] For example, as shown, gas inlet 252 can be connected to ozone generator 262. Ozone generator 262 can produce ozone gas, which is fed directly into internal volume 255 through gas inlet 252. Ozone gas may include a mixture of O2 and O3. The O3 concentration in the ozone gas may be in the range of about 1% to about 50%. HF gas can be directly fed into internal volume 255 from HF gas source 264 (HF bottle) through gas inlet 252. In some embodiments, HF gas may be HF vapor. Carrier gas can be directly fed into internal volume 255 from carrier gas source 266 (carrier gas bottle) through gas inlet 252. Carrier gas may be nitrogen and / or an inert gas.

[0049] Process gases can be exposed to the workpiece for one process cycle. The process cycle can range from about 5 seconds to about 600 seconds. In some embodiments, the process cycle can range from about 30 seconds to about 90 seconds. After the process cycle, the process gases can be extracted from the processing chamber (e.g., using pump port 270).

[0050] In some embodiments, a remote plasma source can be used to generate HF gas (e.g., HF vapor). Figure 4 An example processing apparatus 300 is depicted that can be used to implement an etching process according to an example embodiment of the present disclosure. The processing apparatus 300 is a plasma processing apparatus having an inductively coupled plasma source. As shown, the plasma processing apparatus 300 includes a processing chamber 310 and a plasma chamber 320 spaced apart from the processing chamber 310. The processing chamber 310 includes a substrate holder or workpiece support 312 operable to hold a workpiece 314 (e.g., a semiconductor wafer) to be processed. In this example illustration, plasma can be generated in the plasma chamber 320 (i.e., the plasma generation region) via an inductively coupled plasma source 335, and the desired material is guided from the plasma chamber 320 to the surface of the workpiece 314 via a separation grid assembly 400.

[0051] For purposes of illustration and discussion, aspects of this disclosure are discussed with reference to inductively coupled plasma sources. Those skilled in the art who use the disclosure provided herein will understand that any plasma source (e.g., inductively coupled plasma source, capacitively coupled plasma source, etc.) can be used without departing from the scope of this disclosure.

[0052] Plasma chamber 320 may include dielectric sidewalls 322 and a canopy 324. The dielectric sidewalls 322, canopy 324, and separation grid 400 define a plasma chamber interior 325. The dielectric sidewalls 322 may be formed of a dielectric material (e.g., quartz and / or alumina). An inductively coupled plasma source 335 may include an induction coil 330 disposed near the dielectric sidewalls 322 surrounding the plasma chamber 320. The induction coil 330 is coupled to an RF power generator 334 via a suitable matching network 332. Process gases (e.g., reactants and / or carrier gases) may be supplied to the chamber interior from a gas supply 350 and an annular gas distribution channel 351 or other suitable gas introduction mechanism. Plasma can be generated in the plasma chamber 320 when the induction coil 330 is excited by RF power from the RF power generator 334. In a particular embodiment, the plasma processing apparatus 300 may include an optional grounded Faraday shield 328 to reduce capacitive coupling between the induction coil 330 and the plasma.

[0053] like Figure 3 As shown, the separation grid 400 separates the plasma chamber 320 from the processing chamber 310. The separation grid 400 can be used to ion filter the mixture generated by the plasma in the plasma chamber 320 to produce a filtered mixture. The filtered mixture can then be exposed to the workpiece 314 in the processing chamber 310.

[0054] In some embodiments, the separation grid 400 may be a multi-plate separation grid. For example, the separation grid 400 may include a first grid plate 410 and a second grid plate 420 spaced parallel to each other. The first grid plate 410 and the second grid plate 420 may be separated by a distance.

[0055] The first grid plate 410 may have a first grid pattern with multiple holes. The second grid plate 420 may have a second grid pattern with multiple holes. The first grid pattern may be the same as or different from the second grid pattern. Charged particles can recombine on the walls in their path through the holes of each grid plate 410, 420 in the separated grid 400. Neutral particles (e.g., free radicals) can flow relatively freely through the holes in the first grid plate 410 and the second grid plate 420. The size of the holes and the thickness of each grid plate 410 and 420 can affect the permeability for both charged and neutral particles.

[0056] In some embodiments, the first grid plate 410 may be made of a metal (e.g., aluminum) or other conductive material, and / or the second grid plate 420 may be made of a conductive or dielectric material (e.g., quartz, ceramic, etc.). In some embodiments, the first grid plate 410 and / or the second grid plate 420 may be made of other materials, such as silicon or silicon carbide. When the grid plate is made of a metal or other conductive material, the grid plate may be grounded. In some embodiments, the separate grid 400 comprises a single grid plate. In some embodiments, the separate grid comprises three or more grid plates.

[0057] In some embodiments, Figure 2 The method can be used Figure 4 The plasma processing apparatus 300 is used for implementation. For example, a workpiece 314 can be placed on a workpiece support 312. The workpiece 314 may include, for example, a titanium and / or titanium nitride layer. A temperature control system, for example, can be used. Figure 4 (Not shown in the image), for example, a heater in the workpiece support 312, a fluid channel in the workpiece support 312, a lamp, a laser or other heat source heats the workpiece to the process temperature.

[0058] Process gas 450 can be introduced into plasma chamber 325. The process gas may include, for example, F-containing gases (e.g., CF4, NF3, CF2). x H y (etc.) and H-containing gases (e.g., H2, CH4, C2H8, etc.). HF radicals 455 generated in the plasma can be transported downstream from the plasma chamber 325 to the processing chamber 310 to expose the workpiece 314.

[0059] Ozone gas 362 (e.g., from an ozone generator) can be directly introduced into the processing chamber 310 from the gas inlet 360. In this way, HF gas (e.g., HF radical 455) and ozone gas 362 can be simultaneously introduced into the processing chamber 310 to expose the workpiece 314 for etching processes according to exemplary aspects of this disclosure.

[0060] The co-flow process gases, including HF and ozone, can be introduced into the processing chamber 310 in other ways without departing from the scope of this disclosure, for example, using a gas inlet at or below the separation grid 400. For example, Figure 5 An example injection of process gas at a separation grid according to an exemplary embodiment of the present disclosure is depicted. More specifically, the separation grid 400 includes a first grid plate 410 and a second grid plate 420 arranged in parallel for ion / UV filtration.

[0061] The first grid plate 410 and the second grid plate 420 may be parallel to each other. The first grid plate 410 may have a first grid pattern with a plurality of holes. The second grid plate 420 may have a second grid pattern with a plurality of holes. The first grid pattern may be the same as or different from the second grid pattern. After the second grid plate 420, a gas injection source 430 may be configured to introduce gas at the separation grid. The gas may pass through a third grid plate 435 to expose the workpiece. In some embodiments, the gas injected from the gas injection source 430 may be ozone gas. Ozone gas may be injected into other components of the process gas (e.g., HF gas and / or carrier gas) passing through the separation grid 400. In some embodiments, the process gas (e.g., ozone gas, HF gas, and / or carrier gas) may be introduced into the separation grid 400 from the gas injection source 430.

[0062] For illustrative purposes, this example is discussed with reference to a separate grid having three grid plates. Those skilled in the art who use the disclosure provided herein will understand that more or fewer grid plates can be used without departing from the scope of this disclosure. Furthermore, the gas injection source 430 may be located at other positions relative to the separate grid 400, such as between the first grid plate 410 and the second grid plate 420, below the third grid plate 435, or entirely below the separate grid 400. The gas injection source 430 may inject gas at any angle relative to the separate grid 400.

[0063] Figure 6 A flowchart illustrating an example method (500) according to an exemplary aspect of this disclosure is provided. The method (500) can be implemented in a processing apparatus, such as any processing apparatus described herein. However, as will be discussed in detail below, the method according to an exemplary aspect of this disclosure can be implemented using other methods without departing from the scope of this disclosure. For purposes of illustration and discussion, Figure 6 The steps are described in a specific order. Those skilled in the art who use the disclosure provided herein will understand that the individual steps of any method described herein can be omitted, extended, performed concurrently, rearranged, and / or modified in various ways without departing from the scope of this disclosure. Furthermore, various additional steps (not shown) may be performed without departing from the scope of this disclosure.

[0064] At (502), the method may include placing a workpiece on a workpiece support (e.g., a base) within a processing chamber. The workpiece may be a semiconductor wafer. In some embodiments, the workpiece may include a titanium layer and / or a titanium nitride layer. The workpiece may include other material layers, including one or more of silicon, polycrystalline silicon, silicon-germanium, silicon nitride, silicon dioxide, metals (e.g., tungsten), tantalum nitride, low-k materials, etc.

[0065] At (504), the method may include exposing the workpiece to a first process gas comprising HF gas. In some embodiments, the HF gas may comprise HF vapor. As described herein, the HF gas is introduced directly into the processing chamber and / or generated using a remote plasma source. The first process gas may comprise a carrier gas. In some embodiments, the first process gas does not include ozone gas.

[0066] At (506), the method may include exposing the workpiece to a second process gas entering a processing chamber. The second process gas may include ozone gas. In some embodiments, the second process gas is introduced after the workpiece has been exposed to a first process gas. The second process gas may include a carrier gas. In some embodiments, the second process gas does not include HF gas.

[0067] As shown in (508), blocks (504) and (506) can be repeated in a cyclic manner to etch the titanium and / or titanium nitride layer on the workpiece. Each cycle can remove a small amount of titanium nitride and / or titanium (e.g., about 1 to about 5 angstroms). This allows for precise control of the etching process by controlling the number of cycles.

[0068] At (510), the method may include removing a workpiece from the processing chamber. The processing chamber may then be processed and / or cleaned, and the next workpiece may be placed in the processing chamber.

[0069] Figure 7 Example process results according to example embodiments of the present disclosure are depicted. Figure 7 Example etching rates of titanium nitride and titanium layers at different temperatures by exposure to co-current HF gas and ozone gas according to exemplary embodiments of the present disclosure are depicted. Figure 7 The temperature along the horizontal axis and the etching rate along the vertical axis are plotted. Column 602 depicts the etching rate of titanium nitride deposited using physical vapor deposition (PVD) due to the workpiece being exposed to a co-current flow of HF and ozone gas at 200°C. Column 604 depicts the etching rate of titanium nitride deposited using atomic layer deposition (ALD) due to the workpiece being exposed to a co-current flow of HF and ozone gas at 200°C. Column 606 depicts the etching rate of titanium nitride deposited using physical vapor deposition (PVD) due to the workpiece being exposed to a co-current flow of HF and ozone gas at 250°C. Column 608 depicts the etching rate of titanium nitride deposited using ALD due to the workpiece being exposed to a co-current flow of HF and ozone gas at 250°C. Column 610 depicts the etching rate of titanium due to the workpiece being exposed to a co-current flow of HF and ozone gas at 250°C.

[0070] Figure 8An example process result 700 for selectively etching titanium nitride relative to various materials when using a co-flow of ozone gas and HF gas, according to an example aspect of this disclosure, is described. Figure 8 Various materials were drawn along the horizontal axis. Figure 8 The etching rate is plotted along the vertical axis. Example process results 700 are summarized in the table below.

[0071]

[0072] While the subject matter has been described in detail with respect to specific exemplary embodiments thereof, it should be understood that those skilled in the art will readily make changes, variations, and equivalents to these embodiments upon gaining an understanding of the foregoing. Therefore, the scope of this disclosure is illustrative rather than limiting, and this subject matter disclosure does not exclude the inclusion of such modifications, variations, and / or additions to the subject matter, which will be apparent to those skilled in the art.

Claims

1. A method of processing a workpiece, comprising: placing a workpiece on a workpiece support in a processing chamber, the workpiece comprising a titanium-containing layer and a silicon-containing layer, introducing a first process gas into the processing chamber, the first process gas comprising an HF gas formed from a remote plasma using a remote plasma source; exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the first process gas; after exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the first process gas, introducing a second process gas into the processing chamber, the second process gas comprising an ozone gas; exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the second process gas.

2. The method according to the preceding claim 1, wherein, the silicon-containing layer comprises silicon germanium.

3. The method according to the preceding claim 1, wherein, the titanium-containing layer comprises titanium nitride.

4. The method according to the preceding claim 1, wherein, the first process gas does not comprise an ozone gas.

5. The method according to the preceding claim 1, wherein, the second process gas does not comprise an HF gas.

6. The method according to the preceding claim 1, wherein, the method comprises cyclically repeating: introducing a first process gas into the processing chamber; exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the first process gas; after exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the first process gas, introducing a second process gas into the processing chamber; and exposing the titanium-containing layer and the silicon-containing layer on the workpiece to the second process gas.

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