JP2013048127A - Recovery of side wall after ashing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel process in which a low K thin film is exposed to an environment which is possible to increase effective dielectric constant and limit performance of a device, and then a lower effective dielectric constant is maintained.SOLUTION: A method is provided which lowers an effective dielectric constant present between two conductive components of an integrated circuit. The method accompanies use of selective vapor phase etching on a portion of a low K dielectric layer which is rich in oxygen. The etching speed decreases when the etching process passes a portion which is rich in oxygen with relatively high K and reaches a low K portion. Since a low K portion where a vapor-phase etching process is desired is not easily removed, a timing of etching process can be easily matched.

Description

  Integrated circuit fabrication methods have reached the stage where hundreds of millions of transistors are routinely formed on a single chip. Each new generation of manufacturing technology and equipment is enabling industrial scale manufacturing of smaller and faster transistors, but the difficulty of fabricating smaller and faster circuit elements is also increasing. The dimensions of the circuit elements have become smaller and now well below the 50 nm threshold, which allows chip designers to improve (or simply maintain) the electrical performance of integrated circuits with new low resistivity conductive materials And new low dielectric constant (ie low k) insulating materials.

  As the number of transistors per area increases, parasitic capacitance becomes a significant obstacle to transistor switching speed. There is a capacitance between all adjacent electrically isolated conductors in the integrated circuit, and whether the conductive part is in the “pre-process” or “post-process” of the manufacturing process flow. Nevertheless, there is a possibility of limiting the switching speed.

  Accordingly, there is a need for new techniques and materials that form low-k materials between adjacent conductors. One type of material used to provide low K separation between conductors is available from Applied Materials, Inc., Santa Clara, California. Oxidized organosilane thin film such as Black Diamond ™ thin film commercially available from These thin films have a lower dielectric constant (eg, about 3.5 or less) than conventional spacer materials such as silicon oxides and nitrides. Unfortunately, some new processes involve exposing low K thin films to environments that can increase the effective dielectric constant and limit device performance.

  Therefore, there is a need for new processes that maintain lower effective dielectric constants after exposing low K thin films to such environments.

  A method for reducing the effective dielectric constant present between two conductive components of an integrated circuit is described. The method involves the use of a gas phase etch that is selective to the oxygen rich portion of the low K dielectric layer. The etch rate decreases when the etch process passes through a relatively high K oxygen rich portion and reaches a low K portion. Since the low K portion where a vapor phase etch process is desirable is not easily removed, the timing of the etch process can be easily matched.

  Embodiments of the present invention include a method for reducing the effective dielectric constant of a low K dielectric material between two trenches on a patterned substrate in a substrate processing region. The low K dielectric material forms the walls of the two trenches. The method includes transporting a patterned substrate into a substrate processing region. The method further includes lowering the average dielectric constant of the low K dielectric material by vapor phase etching the patterned substrate and removing the outer dielectric layer from the low K dielectric material.

  Additional embodiments and features will be set forth in part in the following description, and will be apparent to those skilled in the art upon review of the specification or may be learned by practice of the disclosed embodiments. The features and advantages of the disclosed embodiments may be realized and attained by means of the instrumentalities, combinations and methods described herein.

  A further understanding of the nature and advantages of the disclosed embodiments can be obtained by reference to the remaining portions of the specification and the drawings.

FIG. 6 is a cross-sectional view of a gap during treatment according to a disclosed embodiment. FIG. 6 is a cross-sectional view of a gap during treatment according to a disclosed embodiment. 5 is a flow diagram of a process for removing a photoresist that fills a gap, according to disclosed embodiments. FIG. 3 is a cross-sectional view of a processing chamber according to disclosed embodiments. 1 is a diagram of a processing system according to disclosed embodiments. FIG.

  In the accompanying drawings, similar components and / or features may have the same reference label. Further, different components of the same type may be distinguished by following a reference label followed by a dash and a second label that distinguishes between similar components. Where only the first reference label is used herein, the description applies to any of the similar components having the same first reference label, regardless of the second reference label.

  A method for reducing the effective dielectric constant present between two conductive components of an integrated circuit is described. The method involves the use of a gas phase etch that is selective to the oxygen rich portion of the low K dielectric layer. The etch rate decreases when the etch process passes through a relatively high K oxygen rich portion and reaches a low K portion. Since the low K portion where a vapor phase etch process is desirable is not easily removed, the timing of the etch process can be easily matched. Vapor phase etch is particularly preferred for liquid buffered oxide etch for processing patterned substrates. Vapor phase etchants are removed from the confined structure more easily than liquid etchants.

  Embodiments of the present invention are directed to a method of etching low K material on a patterned substrate to increase the effective dielectric constant, thereby improving device performance. An exemplary process flow that benefits from the methods presented herein involves two separate litho-etch patterns transferred to a substrate. Such a process can be designed to pattern the substrate twice in order to obtain the desired step in a non-conventional via structure with relatively straight vertical walls. Such a process sequence may require that the patterned substrate be coated with photoresist so that the photoresist extends into vias and other gaps in the low K material. Photoresist removal usually involves ashing, ie exposing the structure to an oxidized precursor. While removing the photoresist filling the gap, the ashing process also changes the sidewalls of the gap to increase the dielectric constant in the thin outer layer of low K material. Some ash involves exposure to compounds containing oxygen excited in the plasma. In such a case, the oxygen treatment oxidizes the surface of the low K material, increasing the oxygen content relative to the carbon content. The method presented herein removes this thin layer of relatively high K material to lower the dielectric constant and return it to near its pre-ash level.

  To better understand and appreciate the present invention, reference is now made to FIGS. 1-2, which are cross-sectional views of a gap during treatment and a flow chart for treating the gap according to the disclosed embodiments. The structure shown in FIG. 1A is obtained by a litho-etch-litho-etch procedure, in which a second lithographic-etch step opens a wide trench in the low dielectric constant material 110-1. The second etch penetrates only part of the path to the bottom of the trench, leaving a step in the low K material 110-1. Above and below the steps, there will be substantially vertical walls made of low K material. The wall may deviate from the theoretically normal line shown in FIGS. 1A-1B, but in the disclosed embodiments can be within 10 °, 5 °, or 2 ° from the vertical state. After the second etch, some of the photoresist 120 remains towards the bottom of the trench, but it needs to be removed before filling the gap with metal. The process of removing the remaining photoresist 120 begins when the patterned substrate is transferred into the processing chamber (step 210). A stream of oxygen radicals is sent into the ashing chamber (step 215) to remove the photoresist from the trench. In the example illustrated in FIG. 1A, a silicon carbonitride (SiCN) layer 125-1 is included to protect the low K material 110-1 from metal diffusion from the underlying material. The SiCN layer 125-1 is altered by oxygen radicals to remove the portion at the bottom of the SiCN trench, resulting in a patterned SiCN layer 125-2. An exemplary SiCN layer is Blok ™ available from Applied Materials, Santa Clara, California. Some embodiments may have a SiCN layer, and some embodiments may not. The flow of oxygen radicals also oxidizes the walls of the low K material 110 and undesirably increases the dielectric constant near the surface (trench walls). An exemplary low K material is silicon oxycarbide (SiOC) and an exemplary SiOC product is Black Diamond ™, also available from Applied Materials. Ignoring the formation of oxygen-rich (relatively high K) surface layers and continuing the gap-fill deposition of the trench with metal would limit the mode of operation of the completed device.

  The following steps can be used to restore the reduced dielectric constant of the low K material 110 to near the pre-ash level. The patterned substrate is transferred to the substrate etch area of the processing chamber for subsequent processing (step 220). A flow of ammonia and nitrogen trifluoride is provided in the plasma region remote from the processing region (step 222). The remote plasma region may be referred to herein as a remote plasma region and may be a module separate from the processing chamber or compartment within the processing chamber. The remote plasma effluent (product from the remote plasma) is flowed into the processing region and allowed to interact with the substrate surface (step 225). The plasma effluent stream reacts with the surface to produce a solid residue containing material from the plasma effluent and material from the walls of the affected low K material 110. Detailed chemical reactions that may be useful in understanding this process are presented in the Example Equipment section. The solid residue is then removed by heating the patterned substrate above its sublimation point (step 240). The process is completed by removing the patterned substrate from the substrate etch region (step 245), and the resulting structure is shown in FIG. 1B.

  The etch rate of the outer dielectric layer is greater than the relatively low K dielectric material inside the outer dielectric layer. In embodiments of the invention, the gas phase etch rate of the outer dielectric layer is more than 25, 50, or 100 times greater than the etch rate of the remaining portion of the low K dielectric material. The thickness of the outer dielectric layer is, in embodiments, less than 150 mm or about 150 mm, less than 100 mm or about 100 mm, or less than 50 mm or about 50 mm.

  The exemplary process described herein is a subset of the family of SiConi (TM) etches, typically with concurrent fluorine-containing precursors and hydrogen-containing precursor streams. Fluorine-containing precursors include, in different embodiments, nitrogen trifluoride, hydrogen fluoride, diatomic fluorine, monoatomic fluorine, and hydrocarbons substituted with fluorine, or combinations thereof. The hydrogen-containing precursor includes, in different embodiments, atomic hydrogen, diatomic hydrogen, ammonia, hydrocarbons, incompletely halogenated hydrocarbons, or combinations thereof. For brevity, some discussion included herein may refer to an exemplary SiConi ™ etch using a combination of ammonia and nitrogen trifluoride. Any SiConi ™ etch can be used in place of the exemplary described and shown in FIG. All SiConi ™ etches containing fluorine and hydrogen (but little or essentially no oxygen) exhibit strong selectivity for silicon oxide etching. This etch process removes silicon, polysilicon and silicon oxycarbide very slowly. As a result, the SiConi ™ leaves the desired silicon oxycarbide low K material 110 that remains essentially intact even if the etch continues after the silicon oxide is consumed from the walls of the low K material 110. Has further benefits. This selectivity allows the process to be timed without using any other form of endpoint determination.

  The example described herein relates to dual patterning (LELE) of a low K dielectric layer, but other processes that require the deposition of photoresist within the gap in the low K layer. A flow is also possible. As a result, the presented and claimed methods are useful for any application involving ashing of any gap filling material suitable for removal by an oxidative treatment. Ashable gap fill materials include bottom or top antireflective coatings (BARC or TARC), as well as various photoresists and other similar carbon containing materials. In the disclosed embodiment, the ashable gap filling material is essentially free of oxygen. Oxidation treatment removes the ashable gap filling material, but undesirably changes the walls and increases the dielectric constant of the altered surface layer. Using the methods described herein, the increased dielectric constant can be lowered. The trench profile may include a step structure on the walls of the trench as shown in FIGS. 1A-1B, but in other disclosed embodiments, there are essentially no steps.

  As described previously, gaps and trenches are formed in the low K material. In the exemplary gap described above, there is a step between two generally vertical walls in the low K material (see FIG. 1). In other embodiments, no steps are formed, and a single substantially vertical wall is formed in the low K material. In disclosed embodiments, a single vertical wall can be within 10 °, 5 °, or 2 ° from the vertical state. In disclosed embodiments, before ashing (or after the treatment presented herein), the dielectric constant of the low K material is 3.9, 3.7, 3.5, 3.3 or 3.1. It can be made smaller. The dielectric constant is primarily determined by the concentration of carbon in the low-K layer of silicon oxycarbide. According to embodiments of the invention, after ashing, the outer dielectric layer may have a dielectric constant greater than 3.0, 3.2 or 3.5, while the rest of the low K dielectric material Each has a dielectric constant less than 3.0, 3.2, or 3.5.

An optional step can be used after vapor phase etching. The vapor phase etching described herein may leave a post-etch residue containing multiple portions of the vapor phase etchant. The presence of residues after etching can lead to leakage between adjacent conductive lines. Leakage may be caused by a post-etch residue containing, for example, fluorine. Thus, the etched substrate continues to remove one or more of Ar, N ₂ , NH _3, and H ₂ to remove some of the post-etch residue and mitigate any leakage that may have been present. Can be treated with plasma effluent from a plasma containing.

During step 215, oxygen radicals are used to remove the photoresist 120 filling the gap. Oxygen radicals are typically formed in the remote plasma region and flowed to the substrate etch region. In embodiments, the oxygen radical contains a natural chemical species that includes one or more of atomic oxygen (O) and ozone (O ₃ ). However, some ionized species may be present in the etched region, and ionized species tend to recombine faster than non-ionized (natural) atomic oxygen and non-ionized ozone. is there. In an embodiment, a remote plasma is preferred over a plasma in the etched region to ensure that the ionized species has sufficient opportunity to neutralize. In the disclosed embodiment, the opening and path length from the remote plasma to the etching region is preferably selected so that natural atomic oxygen (O) can move to the substrate etching region. In some embodiments, SiF ₄ is flowed simultaneously with oxygen radicals (using remote plasma or plasma in the etched region) to deactivate the sidewalls and reduce oxidation. Again, an oxidized region of low-K material is produced and can exhibit a high dielectric constant. Thus, the structure thus produced can still benefit from the methods disclosed herein.

  So far, a remote chamber has been described for use in ashing and SiConi ™ etching. In an alternative embodiment, these processes are performed by a series of processing steps in the same chamber without removing the patterned substrate from the processing chamber.

  In describing an exemplary processing system, additional vapor phase etch process parameters and process details are disclosed.

Exemplary Processing System FIG. 3 is a partial cross-sectional view illustrating an exemplary processing chamber 300 in which embodiments of the present invention may be implemented. In general, ammonia and nitrogen trifluoride can be introduced into the remote plasma region (s) 361-363 through one or more openings 351 and excited by the plasma power source 346.

  In one embodiment, the processing chamber 300 includes a chamber body 312, a lid assembly 302 and a support assembly 310. The lid assembly 302 is disposed at the upper end of the chamber body 312 and the support assembly 310 is disposed at least partially within the chamber body 312. The processing chamber 300 and associated equipment is preferably formed from a material (eg, aluminum, stainless steel, etc.) that is compatible with one or more processes.

  The chamber body 312 includes a slit valve opening 360 formed in a sidewall thereof to form an entry path into the processing chamber 300. The slit valve opening 360 is selectively opened and closed to allow access to the interior of the chamber body 312 by a wafer handling robot (not shown). In one embodiment, the wafer can be carried into the processing chamber 300 and through the slit valve opening 360 from the processing chamber 300 to an adjacent transfer chamber and / or load lock chamber, or other chamber in the cluster tool. . FIG. 4 illustrates an exemplary cluster tool that can include a processing chamber 300.

  In one or more embodiments, the chamber body 312 includes a chamber body flow path 313 for flowing heat transfer fluid through the chamber body 312. The heat transfer fluid can be a heating fluid or a coolant and is used to control the temperature of the chamber body 312 during processing and substrate transfer. The temperature of the chamber body 312 is important to prevent unwanted gas condensation or by-products on the chamber walls. Exemplary heat transfer fluids include water, ethylene glycol or mixtures thereof. An exemplary heat transfer fluid may also include nitrogen gas. The support assembly 310 can have a support assembly flow path 304 for flowing heat transfer fluid through the support assembly 310, thereby affecting the temperature of the substrate.

  The chamber body 312 can further include a liner 333 that surrounds the support assembly 310. The liner 333 is preferably removable for repair and cleaning. The liner 333 can be made of a metal such as aluminum or a ceramic material. However, the liner 333 can be any material compatible with the process. The liner 333 can be bead blasted to enhance adhesion of any material disposed thereon, thereby preventing delamination of the material that results in contamination of the processing chamber 300. In one or more embodiments, the liner 333 includes one or more openings 335 and a pumping channel 329 formed therein and in fluid communication with the vacuum system. The opening 335 forms a path for gas flow into the pumping flow path 329, and the pumping flow path 329 forms an outlet for the gas in the processing chamber 300.

  The vacuum system can include a vacuum pump 325 and a throttle valve 327 to regulate the flow of gas through the processing chamber 300. The vacuum pump 325 is coupled to a vacuum port 331 disposed in the chamber body 312 and is therefore in fluid communication with a pumping flow path 329 formed in the liner 333. The terms “(one) gas” and “(multiple) gas” are used interchangeably unless otherwise stated, and include one or more reactants, catalysts, supports, purges, cleanings, Refers to the combination as well as any other fluid introduced into the chamber body 312. The term “precursor” is used to refer to any process gas involved in a reaction that removes or deposits material from a surface.

  The opening 335 allows the pumping flow path 329 to be in fluid communication with the processing region 340 in the chamber body 312. The processing area 340 is defined by the lower surface of the lid assembly 302 and the upper surface of the support assembly 310 and is surrounded by the liner 333. The openings 335 are defined to have a uniform size and can be arranged around the liner 333 at equal intervals. However, as will be discussed in more detail below, any number, location, size or shape of openings can be used, each of which is a desired flow of gas across the surface receiving the substrate. It may change depending on the pattern. In addition, the size, number and location of the openings 335 are configured to obtain a uniform flow of gas exiting the processing chamber 300. Further, the size and arrangement of the openings can be configured to allow rapid or high volume pumping to facilitate rapid exhaust of gas from the chamber 300. For example, the number and size of the openings 335 very close to the vacuum port 331 can be smaller than the size of the openings 335 positioned further away from the vacuum port 331.

  A gas supply panel (not shown) is typically used to provide process gas (es) to processing chamber 300 through one or more openings 351. The particular gas (s) used depends on the process (es) performed in the chamber 300. The illustrative gas can include, but is not limited to, one or more precursors, reducing agents, catalysts, supports, purges, cleanings, or any mixture or combination thereof. Typically, one or more gases introduced into the processing chamber 300 flow into the plasma volume 361 through the opening (s) 351 in the top plate 350. Alternatively or alternatively, process gas may be introduced more directly into process region 340 through opening (s) 352. The opening (s) 352 may be useful for processes involving gases that do not require plasma excitation or that do not benefit from excitation of additional gases, by omitting remote plasma excitation. Reactive oxygen generated in the remote plasma can be introduced into the processing region 340 through the opening (s) without passing through the regions 361, 362, and 363. Electronically operated valves and / or flow control mechanisms (not shown) can be used to control the flow of gas from the gas supply into the processing chamber 300. Depending on the process, any number of gases can be delivered to the processing chamber 300 and the gases can be mixed in the processing chamber 300 or prior to delivering the gases to the processing chamber 300. .

  The lid assembly 302 can further include an electrode 345 to generate a plasma of reactive chemical species within the lid assembly 302. In one embodiment, the electrode 345 is supported by the top plate 350 and is made of aluminum oxide or any other insulating and process compatible material for electrical insulation (s). Electrical isolation from top plate 350 is achieved by inserting ring 347. In one or more embodiments, the electrode 345 is coupled to a power source 346 and the rest of the lid assembly 302 is connected to ground. In response, one or more process gas plasmas may be generated in a remote plasma region comprised of volumes 361, 362 and / or 363 between the electrode 345 and the annular mounting flange 322. In an embodiment, the annular mounting flange comprises or supports the gas delivery plate 320. For example, plasma can be provided and maintained between electrode 345 and one or both blocker plates of blocker assembly 330. Alternatively, when the blocker assembly 330 is not present, plasma can be applied between the electrode 345 and the gas delivery plate 320 and housed. In either embodiment, the plasma is suitably confined or contained within the lid assembly 302. Accordingly, the plasma is a “remote plasma” because the active plasma does not directly contact the substrate disposed within the chamber body 312. As a result, since the plasma is separated from the substrate surface, damage to the substrate due to the plasma can be avoided.

  A wide variety of power sources 346 can activate ammonia gas and nitrogen trifluoride gas into reactive chemical species. For example, radio frequency (RF), direct current (DC) or microwave (MW) based power discharge technologies can be used. Activation may be caused by exposure to heat-based techniques, gas breakdown techniques, high intensity light sources (eg UV energy), or X-ray sources. Alternatively, a plasma of reactive species is generated using a remote activation source, such as a remote plasma generator, which is then delivered into the chamber 300. Exemplary remote plasma generators are available from MKS Instruments, Inc. And Advanced Energy Industries, Inc. Available from such suppliers. In the exemplary processing system, an RF power source is coupled to electrode 345. A higher power microwave power source 346 is beneficial when reactive oxygen is also generated using the power source 346.

  The temperature of the process chamber body 312 and the substrate can each be controlled by flowing a heat transfer medium through the chamber body flow path 313 and the support assembly flow path 304, respectively. A support assembly flow path 304 may be formed in the support assembly 310 to facilitate the transfer of thermal energy. The chamber body 312 and the support assembly 310 can be cooled or heated independently. For example, heated fluid can flow through one and cooling fluid can flow through the other.

  Other methods can be used to control the temperature of the substrate. The substrate can be heated by heating the support assembly 310 (or a portion thereof, such as a pedestal) using a resistance heater or by some other means. In other configurations, the gas delivery plate 320 can be maintained at a higher temperature than the substrate, and the substrate can be raised to increase the temperature of the substrate. In this case, the substrate is heated by radiation or by using a gas that transfers heat from the gas delivery plate 320 to the substrate. The substrate can be raised by raising the support assembly 310 or by using lift pins.

  During the etch process described herein, the chamber body 312 may have a suitable temperature in different embodiments between 50 ° C. and 80 ° C., between 55 ° C. and 75 ° C., or between 60 ° C. and 70 ° C. Can be kept within range. During exposure to plasma effluent and / or oxidant, the substrate, in different embodiments, is less than about 100 ° C., less than about 65 ° C., between about 15 ° C. and about 50 ° C., or between about 22 ° C. and about 40 ° C. Can be maintained.

The plasma effluent contains various molecules, molecular fragments and ionized species. Although the theoretical mechanism currently considered for SiConi ™ etching may or may not be perfectly adequate, the plasma effluent easily reacts with the cold substrate described herein. NH ₄ F and NH ₄ F. It is thought to contain HF. The plasma effluent can react with the surface of the silicon oxide to form (NH ₄ ) ₂ SiF ₆ , NH ₃ and H ₂ O products. NH ₃ and H ₂ O are vapors under the processing conditions described herein and can be removed from the processing region 340 by a vacuum pump 325. A thin continuous or discontinuous layer of (NH ₄ ) ₂ SiF ₆ solid byproduct is left on the substrate surface.

After exposure to the plasma effluent and accumulation of associated solid byproducts on the vertical walls of the trench (including stepped trenches), when the relatively high K thin film is removed from the low K material, The substrate can be heated to remove by-products. In embodiments, the gas delivery plate 320 can be heated by incorporating a heating element 370 in or near the gas delivery plate 320. The substrate can be heated by reducing the distance between the substrate and the heated gas delivery plate. The gas delivery plate 320 can be heated to between about 100 ° C. and 150 ° C., between about 110 ° C. and 140 ° C., or between about 120 ° C. and 130 ° C. in different embodiments. By reducing the separation between the substrate and the heated gas delivery plate, the substrate is in different embodiments above about 75 ° C, above about 90 ° C, above about 100 ° C, or from about 115 ° C to about 150 ° C. It can be heated up to between. The heat radiated from the gas delivery plate 320 to the substrate is volatile SiF ₄ , which can be pumped away from the processing region 340 as solid (NH ₄ ) ₂ SiF ₆ on the substrate dissociates or sublimes. It should be sufficient to be the product of NH ₃ and HF.

  Ammonia (or a precursor containing hydrogen in general), in different embodiments, is between about 50 seem and about 300 seem, between about 75 seem and about 250 seem, between about 100 seem and about 200 seem, or about 120 seem. The remote plasma volume 361 can be flowed at a rate between 170 sccm. Nitrogen trifluoride (or generally a fluorine-containing precursor), in different embodiments, is between about 25 sccm and about 150 sccm, between about 40 sccm and about 175 sccm, between about 50 sccm and about 100 sccm, or about The remote plasma volume 361 can be flowed at a rate between 60 sccm and about 90 sccm. The total flow rate of the hydrogen-containing precursor and fluorine-containing precursor into the remote plasma region can be from 0.05% to about 20% with respect to the total volume of the gas mixture. The rest is carrier gas. In one embodiment, a purge gas or carrier gas is first provided in the remote plasma region prior to the reactive gas to stabilize the pressure in the remote plasma region.

  With respect to the other parts of the lid assembly 302, application of plasma power to the electrode 345 results in the production of plasma effluent in the volumes 361, 362 and / or 363. The power of the plasma can be various frequencies or a combination of frequencies. In the exemplary processing system, the plasma is provided by an RF power delivered to electrode 345. The RF power can be between about 1 W and about 1000 W, between about 5 W and about 600 W, between about 10 W and about 300 W, or between about 20 W and about 100 W in different embodiments. The RF frequency applied to the exemplary processing system can be less than about 200 kHz, less than about 150 kHz, less than about 120 kHz, or between about 50 kHz and about 90 kHz in different embodiments.

During the ashing process, reactive oxygen can be formed outside the processing chamber or in the same chamber (361-362) used to excite the etchant gas. In embodiments, the reactive oxygen can contain atomic oxygen (O) and ozone (O ₃ ) that are flowed with more stable molecular oxygen (O ₂ ), the combination of which is reactive herein. Called oxygen. The reactive oxygen flow rate can be between about 1 slm and about 50 slm, between about 2 slm and about 30 slm, or between about 5 slm and about 10 slm in different embodiments. The reactive oxygen stream can be combined with an additional relatively inert gas (eg, He, Ar) stream prior to entering the processing region 340 through the opening (s) 352. A relatively inert carrier gas can be included for various benefits, including increased plasma density.

  While ozone, oxygen, carrier gas and / or plasma effluent flows into the processing region 340, the processing region 340 can be maintained at various pressures. The pressure may be maintained between about 500 millitorr to about 30 torr, between about 1 torr and about 10 torr, or between about 3 torr and about 6 torr in different embodiments. Even lower pressures can be used in the processing region 340. The pressure is maintained at less than 500 millitorr, less than 250 millitorr or less than about 250 millitorr, less than 100 millitorr or less than about 100 millitorr, less than 50 millitorr or less than about 50 millitorr, or less than 20 millitorr or about 20 millitorr in different embodiments can do.

  In one or more embodiments, the processing chamber 300 is available from Applied Materials, Inc., located in Santa Clara, California. It can be integrated into a variety of multiprocessing platforms, including Producer ™ GT, Centura ™ AP and Endura ™ platform available from: Such processing platforms can perform several processing operations without interrupting the vacuum.

  FIG. 4 is a schematic top view of an illustrative multi-chamber processing system 400. The system 400 can include one or more load lock chambers 402, 404 to transport substrates into and out of the system 400. Since the system 400 is typically under vacuum, the load lock chambers 402, 404 can “pump down” substrates introduced into the system 400. The first robot 410 moves the substrate between the load lock chambers 402, 404 and the first set of one or more substrate processing chambers 412, 414, 416, 418 (four are shown). Can be transported. Each processing chamber 412, 414, 416, 418 is periodic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etch, preclean, degas, orient. A number of substrate processing steps may be performed, including the dry etch process described herein in addition to and other substrate processes.

  The first robot 410 can also transfer the substrate to or from one or more transfer chambers 422, 424. The substrate can be transported within the system 400 while maintaining ultra high vacuum conditions using the transport chambers 422, 424. The second robot 430 can transfer substrates between the transfer chambers 422, 424 and the second set of one or more processing chambers 432, 434, 436, 438. Similar to process chambers 412, 414, 416, 418, process chambers 432, 434, 436, 438 can be, for example, periodic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition, and the like. Various substrate processing steps may be performed including (PVD), etch, preclean, degas and align as well as the dry etch process described herein. Any of the substrate processing chambers 412, 414, 416, 418, 432, 434, 436, 438 may be omitted from the system 400 if not required for a particular process performed by the system 400. The gas can be provided, routed, and mixed by the gas handling system 455 prior to delivery to the exemplary processing chamber.

  The system controller 457 is used to control motors, valves, flow controllers, power supplies, and other functions necessary to perform the process recipes described herein. The system controller 457 may rely on feedback from the optical sensor to determine and adjust the position of the movable mechanical assembly. The mechanical assembly can include a robot, throttle valve and susceptor that are moved by a motor under the control of the system controller 457.

  In the exemplary embodiment, system controller 457 includes a hard disk drive (memory), a USB port, a floppy disk drive, and a processor. The system controller 457 includes analog and digital input / output boards, interface boards, and stepper motor controller boards. Various parts of the multi-chamber processing system 400 including the processing chamber 300 are controlled by a system controller 457. The system controller executes system control software in the form of a computer program stored on a computer readable medium such as a hard disk, floppy disk or flash memory thumb drive. Other types of memory can also be used. The computer program includes a set of instructions that indicate timing, gas mixing, chamber pressure, chamber temperature, RF power level, susceptor position, and other parameters of a particular process.

  The process of depositing a thin film on the substrate or cleaning the chamber 15 can be performed using a computer program product executed by the controller. The computer program code can be written in any conventional computer readable programming language such as, for example, 68000 assembly language, C, C ++, Pascal, Fortran or others. Appropriate program code is entered into a single file or multiple files using a conventional text editor and stored or incorporated in a computer-usable medium, such as a computer memory system. If the entered code text is a high-level language, the code is compiled and the resulting compiler code is then linked with the object code of a precompiled Microsoft Windows library routine. To execute the linked compiled object code, the system user calls the object code and causes the computer system to load the code into memory. The CPU then reads and executes the code to perform the task identified by the program.

  The interface between the user and the controller can be via a touch monitor and can also include a mouse and keyboard. In one embodiment, two monitors are used, one attached to the clean room wall for the operator and the other attached to the back of the wall for the service technician. The two monitors can display the same information at the same time, in which case only one is configured to accept input at a time. To select a particular screen or function, the operator touches the indicated area on the display screen with a finger or mouse. The touched area changes its highlighted color or a new menu or screen is displayed to confirm the operator's selection.

  As used herein, a “substrate” can be a support substrate with or without a layer formed thereon. The support substrate can be an insulator or a semiconductor of various doping concentrations and profiles, and can be, for example, a type of semiconductor substrate used in the manufacture of integrated circuits. The “silicon oxide” layer is used as a simplified representation for and interchangeable with materials containing silicon and oxygen. Thus, silicon oxide can contain certain concentrations of other elemental components such as nitrogen, hydrogen, and carbon. In some embodiments, the silicon oxide consists essentially of silicon and oxygen. An “excited state” gas refers to a gas that is excited, dissociated, and / or ionized, such that at least some of the gas molecules oscillate. The gas can be a combination of two or more gases. The terms “trench” and “gap” are used throughout without implying that the etched shape has a large horizontal aspect ratio. When viewed from above the surface, the trenches and gaps may appear circular, oval, polygonal, rectangular, or various other shapes. The term “via” is used to refer to a trench with a low horizontal aspect ratio (when viewed from above) and filled even if filled with metal to form a vertical electrical connection. It does not have to be.

  While several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative constructions and equivalents may be used without departing from the spirit of the disclosed embodiments. It will be. In addition, in order to avoid unnecessarily obscuring the present invention, some well-known processes and elements are not described. Accordingly, the above description should not be taken as limiting the scope of the invention.

  Where a range of values is given, each value between the upper and lower limits of the range is also specifically disclosed to the tenth of the lower limit unit unless the context clearly dictates otherwise. Understood. Each smaller range between any specified value or values within the specified range and any other specified value or values within the specified range is included. The The upper and lower limits of these smaller ranges may independently be included or excluded from the range, and the smaller ranges may include any of the limit values, none of them, or both. Each of the ranges to be included in the present invention is subject to any limit value specifically excluded within the stated range. Where the stated range includes one or both of the limit values, ranges excluding either or both of those included limit values are also included.

  As used in this specification and the appended claims, the singular forms “a, an” and “the”, unless the context clearly indicates otherwise. Includes the target. Thus, for example, a reference to “a process” includes a plurality of such processes, and a reference to “the dielectric material” includes one or more dielectric materials and equivalents thereof known to those skilled in the art, and the like. Includes mention.

  Also, the words “comprise”, “comprising”, “include”, “including” and “includes” are used herein and in the following. When used in the claims, it is intended to specify the presence of a specified feature, whole body, component, or process, which may be one or more other features, whole body, component. Does not exclude the presence or addition of processes, acts or groups.

110-1 Low dielectric constant material 120 Photoresist 125-1 Silicon carbonitride (SiCN) layer 125-2 Patterned SiCN layer 300 Processing chamber 302 Lid assembly 304 Flow path of support assembly 310 Support assembly 312 Chamber body 313 Chamber flow path 320 Gas delivery plate 325 Vacuum pump 327 Throttle valve 329 Pumping flow path 330 Blocker assembly 331 Vacuum port 322 Annular mounting flange 333 Liner 335 Opening 340 Processing area 345 Electrode 346 Plasma power supply 347 For electrical insulation Ring 350 top plate 351 opening 352 opening 360 slit valve opening 361 remote plasma region, plasma volume, volume, chamber 362 remote plasma region, volume, chamber 3 63 Remote plasma region, volume 370 Heating element 400 Multi-chamber processing system 402, 404 Load lock chamber 410 First robot 412, 414, 416, 418 Substrate processing chamber 422, 424 Transfer chamber 430 Second robot 432, 434, 436 438 Processing chamber 455 Gas handling system 457 System controller

Claims (15)

A method of reducing the effective dielectric constant of a low K dielectric material between two trenches on a patterned substrate in a substrate processing region, wherein the low K dielectric material forms the walls of the two trenches,
Transporting the patterned substrate into the substrate processing region;
Reducing the average dielectric constant of the low K dielectric material by gas phase etching the patterned substrate and removing the outer dielectric layer from the low K dielectric material. The gas phase etching step is
A fluorine-containing precursor and a hydrogen-containing precursor are flowed into a first remote plasma region that is fluidly connected to the substrate processing region, and at the same time, a plasma is formed in the first remote plasma region to form a plasma effluent. Generating
Etching the patterned substrate by flowing plasma effluent into the substrate processing region and simultaneously forming a solid by-product on the surface of the substrate;
And sublimating the solid by-product by raising the temperature of the substrate above the sublimation temperature of the solid by-product.   The fluorine-containing precursor comprises at least one precursor selected from the group consisting of nitrogen trifluoride, hydrogen fluoride, diatomic fluorine, monoatomic fluorine, and hydrocarbons substituted with fluorine. 2. The method according to 2.   The hydrogen-containing precursor comprises at least one precursor selected from the group consisting of atomic hydrogen, molecular hydrogen, ammonia, hydrocarbons, and incompletely halogen-substituted hydrocarbons. The method described in 1.   The method of claim 2, wherein the temperature of the substrate is raised above 100 ° C. or to about 100 ° C. during the step of sublimating the solid by-product.   The method of claim 1, wherein the outer dielectric layer has a dielectric constant greater than 3.0 and the remaining portion of the low K dielectric material has a dielectric constant less than 3.0.   The method of claim 1, wherein a relatively high dielectric constant of the outer dielectric layer is obtained by plasma ashing.   The method of claim 1, further comprising ashing the patterned substrate prior to the vapor phase etching step.   The method of claim 1, wherein the outer dielectric layer is removed from the walls of the two trenches.   9. The method of claim 8, wherein the step of ashing the patterned substrate is performed after the step of transporting the patterned substrate into the substrate processing region.   9. The method of claim 8, wherein the step of plasma ashing the patterned substrate is performed prior to the step of transporting the patterned substrate into the substrate processing region.   The method of claim 1, wherein the thickness of the outer dielectric layer is less than about 150 mm or about 150 mm.   The method of claim 1, wherein the etch rate of the outer dielectric layer exceeds the etch rate of the remaining portion of the low K dielectric material by more than 50 times during vapor phase etching. Following the step of vapor phase etching the patterned substrate, the patterned substrate in an atmosphere containing at least one of argon, nitrogen (N ₂ ), ammonia (NH ₃ ), or hydrogen (H ₂ ) The method of claim 1, wherein plasma is treated to remove post-etch residues.   The method of claim 14, wherein the post-etch residue contains fluorine.