Electrode tuning, depositing, and etching methods, method of forming features over semiconductor substrate, and method of processing semiconductor substrate

Abstract

A method for forming features on a semiconductor substrate is provided. The method includes supplying a gas mixture to a substrate surface at a continuous flow rate. A first radio frequency (RF) signal is transmitted to an electrode while the gas mixture is supplied at a continuous flow rate to deposit a polymer layer on the substrate surface. The substrate surface includes oxide-containing portions and nitride-containing portions. A second RF signal is transmitted to an electrode while the gas mixture is continuously supplied at a continuous flow rate to selectively etch the oxide-containing portions relative to the nitride-containing portions.

Description

Technical Field

[0001] The embodiments described herein are generally related to deposition and highly selective etching processes performed using extreme ultraviolet (EUV) lithography patterned films. Prior Technology

[0002] Reliably generating submicron and smaller features is a critical requirement for ultra-large-scale integration (VLSI) and very large-scale integration (ULSI) of semiconductor devices. However, with the continued miniaturization of circuit technology, the size and spacing of circuit features (such as interconnects) have placed additional demands on processing power. The multi-level interconnects at the core of this technology require precise imaging and placement of high aspect ratio features (such as vias and other interconnects). Reliably forming these interconnects is crucial for further increases in device and interconnect density. Additionally, there is a need to form submicron-sized features and interconnects with reduced waste of intermediate materials (such as resists and hard masking materials).

[0003] As feature sizes shrink, the demand for higher aspect ratios (defined as the ratio between feature depth and feature width) steadily increases to 20:1 and even greater. Developing film stacking and etching processes capable of reliably forming features with such high aspect ratios is a significant challenge. However, inaccurate control or low resolution in lithography and development processes can lead to undesirable critical dimensions in the photoresist layer used to transfer features in the film stack, resulting in unacceptable linewidth roughness (LWR). The large LWR and undesirable wobble profile of the photoresist layer produced by lithography and development processes can lead to inaccurate feature transfer to the film stack, ultimately resulting in equipment failure and yield losses.

[0004] Furthermore, during the etching of the thin film stack, byproducts or redeposited or accumulated materials generated during the etching process can accumulate on the top and / or sidewalls of the etched features, undesirably obstructing the openings of the features formed in the material layer. Different materials selected for the thin film stack can produce different amounts or profiles of byproducts redeposited in the thin film stack. Additionally, as the openings of the etched features narrow and / or are sealed by accumulated redeposited material, reactive etchant is prevented from reaching the lower surface of the features, thus limiting the achievable aspect ratio. Moreover, since the redeposited material or accumulated byproducts can randomly and / or irregularly adhere to the top surface and / or sidewalls of the etched features, the resulting irregular profiles and growth of the redeposited material can alter the flow path of the reactive etchant, resulting in bent or twisted profiles of the features formed in the material layer. Inaccurate profiles or structural dimensions can lead to device structural collapse, ultimately resulting in device failure and low product yield. Poor etch selectivity for the materials included in the thin film stack can undesirably lead to inaccurate profile control, ultimately resulting in device failure. Furthermore, highly selective processes typically produce equipment at relatively low yields.

[0005] Therefore, this technology requires a suitable thin film stacking and etching method for etching features with desired contours and small dimensions in such thin film stacks with high production yield. Summary of the Invention

[0006] In some embodiments, a method for forming features on a semiconductor substrate is provided. The method includes supplying a gas mixture to a substrate surface at a continuous flow rate. A first radio frequency (RF) signal is transmitted to an electrode while the gas mixture is supplied at a continuous flow rate to deposit a polymer layer on the substrate surface. The substrate surface includes oxide-containing portions and nitride-containing portions. A second RF signal is transmitted to an electrode while the gas mixture is continuously supplied at a continuous flow rate to selectively etch the oxide-containing portions relative to the nitride-containing portions.

[0007] In some embodiments, a method of processing a semiconductor substrate is provided, the method comprising positioning the substrate on a substrate support disposed in a process space of a process chamber. The method includes flowing a halogen-containing gas into the process space at a continuous flow rate. A radio frequency (RF) signal is cyclically transmitted to a source electrode disposed on the substrate, which is disposed on the substrate support. Cyclicly transmitting the RF signal includes supplying a first RF signal to the source electrode at a first RF power for a first time period. The method includes reducing the first RF power supplied to the source electrode to a second RF power for a second time period.

[0008] In some embodiments, a method of processing a semiconductor substrate is provided. The method includes positioning the substrate on a substrate support disposed within a process space of a process chamber. The method includes flowing a halogen-containing gas into the process space at a continuous flow rate. Radio frequency (RF) signals are cyclically transmitted to source electrodes disposed on the substrate. Cyclicly transmitting the RF signals to the source electrodes includes supplying bias RF power to a bias electrode coupled to the substrate support for a first time period. The method includes increasing the bias RF power to the bias electrode for a second time period. Simple Explanation of the Diagram

[0009] A more specific description of the present invention, briefly summarized above, can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings, in a manner that enables a detailed understanding of the aforementioned features of the present invention. However, it should be noted that the drawings merely illustrate exemplary embodiments and are therefore not intended to limit the scope of the present invention, and other equally effective embodiments are permissible.

[0010] Figure 1 illustrates a process chamber that can be used to process a substrate according to some embodiments.

[0011] Figure 2 illustrates a flowchart of a method for patterning a substrate according to some embodiments.

[0012] Figure 3 illustrates a flowchart of a method for tuning the radio frequency power of one or more electrodes according to some embodiments.

[0013] Figure 4 illustrates a graphical representation of a radio frequency power signal according to some embodiments.

[0014] Figure 5 illustrates a substrate before and after processing with the methods described herein, according to some embodiments.

[0015] To facilitate understanding, the same element symbols have been used where possible to indicate the same elements shared by the figures. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. Implementation

[0016] Embodiments of this application include a method for forming a thin film stack, and an etching process for etching the thin film stack to form features having a predetermined aspect ratio and profile. The method includes cyclically tuning one or more electrodes disposed in a process chamber to cyclically deposit and etch portions of a substrate according to a predetermined pattern. Instead of switching or providing alternating bursts of gas into the process chamber to deposit and etch portions of the substrate, a continuous flow of a gas mixture is provided to the process space, and the one or more electrodes are tuned to control the deposition and etching process. [Process Chamber]

[0017] Figure 1 is a cross-sectional view of an example of a processing chamber 100 suitable for performing a patterned process to deposit and etch a stack of thin films. Although the processing chamber 100 is illustrated to include a plurality of features for achieving etching performance, it is contemplated that other processing chambers may be adapted to benefit from one or more of the features disclosed herein.

[0018] The plasma processing chamber 100 includes a chamber body 105 having a processing space 101 defined therein. The chamber body 105 has sidewalls 112 and a bottom 118 coupled to ground 126. The sidewalls 112 have gaskets 115 to protect the sidewalls 112 and extend the time between maintenance cycles of the plasma processing chamber 100. The size of the chamber body 105 and associated components of the plasma processing chamber 100 is not limited and can be proportionally larger than the size of the substrate 103 to be processed therein.

[0019] The chamber body 105 supports a cover 404 that encloses the processing space 101. The chamber body 105 may be made of aluminum or other suitable materials. A substrate inlet / outlet port 113 is formed through the sidewall 112 of the chamber body 105 to facilitate the transfer of the substrate 103 into and out of the plasma processing chamber 100. The substrate inlet / outlet port 113 (which is selectively sealed by means of a slit valve) is typically coupled to a transfer chamber and / or other processing chamber of a substrate processing system (not shown) (such as a clustering tool).

[0020] Pumping port 145 is defined in chamber body 105 and connected to processing space 101. Pumping device (not shown) is coupled to processing space 101 via pumping port 145 to vent and control pressure in processing space 101. Pumping device may include one or more roughing pumps, turbo pumps, and throttle valves.

[0021] Gas distribution plate 160 is coupled to chamber body 105 via gas line 167 to supply process gas to processing space 101. Gas distribution plate 160 may include one or more process gas sources 161, 162, 163, 164, and may additionally include inert gas, non-reactive gas and reactive gas if required. Examples of process gases that can be provided by the gas distribution disk 160 include, but are not limited to, halogen-containing gases, including BCl3, Cl2, C4F6, C2F2, HCl, HF, F2, Br2, HCl, HBr, SF6, and NF3; oxygen-containing gases, including O2, H2O, H2O2, O3, N2O, and NO2; hydrogen-containing gases, including H2; carbon-containing gases, such as hydrocarbons, including methane (CH4), acetylene (C2H2), ethylene (C2H4), propylene (C3H6), propane (C3H8), hexane (C6H14), benzene (C6H6), isoprene (C5H8), butadiene (C4H6), and their isomers; and inert gases including argon (Ar) and helium (He). Additionally, process gases may include nitrogen-containing, chlorine-containing, fluorine-containing, oxygen-containing, boron-containing, and hydrogen-containing gases, such as C2F4, C4F8, C4F6, CHF3, CH2F2, CH3F, NF3, NH3, CO2, SO2, CO, N2, NO2, N2O, and H2.

[0022] Valve 166 controls the flow of process gases from process gas sources 161, 162, 163, and 164 from gas distribution plate 160, and valve 166 is managed by system controller 165. The gas flow supplied from gas distribution plate 160 to chamber body 105 may include combinations of gases.

[0023] The cover 110 may include a nozzle or spray nozzle 114. The nozzle 114 has one or more ports for introducing process gas from process gas sources 161, 162, 164, 163 of the gas distribution disc 160 into the processing space 101. After the process gas is introduced into the plasma processing chamber 100, the gas system is excited by a power source to form plasma. An antenna 148, such as one or more inductor coils, may be provided adjacent to the plasma processing chamber 100 to aid in plasma formation. Although the antenna 148 is illustrated as a pair of concentric vertical coils, other coil arrangements, such as coils having vertical portions, horizontal portions, or combinations thereof, are also contemplated. An antenna power supply 142 is used to power the antenna 148 via a matching circuit 141 to inductively couple energy, such as radio frequency energy, to the process gas to sustain the plasma formed by the process gas in the processing space 101 of the plasma processing chamber 100. Alternatively or in addition to antenna power supply 142, processing electrodes below and / or above substrate 103 can be used to couple RF power capacitors to process gas to maintain plasma within processing space 101. Operation of antenna power supply 142 can be controlled by a controller, such as system controller 165, which also controls the operation of other components in plasma processing chamber 100. RF source power 142 is typically capable of generating up to about 8 kilowatts (kW) of power at tunable frequencies ranging from about 50 kHz to about 200 MHz, such as between 1 MHz and 60 MHz, such as between about 2 MHz and about 13.56 MHz, such as between about 50 W and 5000 W, such as between about 500 W and 3000 W, such as between about 500 W and 1000 W.

[0024] A substrate support 135 is disposed in a process space 101 to support a substrate 103 during processing. The substrate support 135 may include an electrostatic chuck (ESC) 122 for holding the substrate 103 during processing. The ESC 122 holds the substrate 103 on the substrate support 135 using electrostatic attraction. The ESC 122 is powered by one or more radio frequency power supplies 125, 127 integrated with matching circuitry 124. In one embodiment, the substrate support 135 is configured as a cathode and includes an electrode 121 embedded in a dielectric body and coupled to a plurality of radio frequency power bias sources 125, 127. In some embodiments, the electrode 121 is an electrostatic clamping (ESC) electrode disposed at a distance (e.g., 1 to 5 millimeters) from the substrate support surface of the ESC. Each of the bias sources provides a bias that attracts plasma ions formed by the process gas in the processing space 101 to the ESC 122 and the substrate 103 thereon. The RF bias power supplies 125, 127 are typically capable of generating RF signals with frequencies from about 50 kHz to about 200 MHz and power from about 0 watts (W) to about 8 kW (such as from about 1 W to about 5 kW). An additional bias power supply 178 (not shown) may be coupled to electrode 121 to control the characteristics of the plasma.

[0025] During the processing of substrate 103, each RF bias power supply 125, 127 can be cyclically turned on and off, or pulsed. ESC 122 has an isolator 128 to reduce the attraction of the sidewalls of ESC 122 to plasma, thereby extending the maintenance life cycle of ESC 122. Furthermore, substrate support 135 may have a cathode liner 136 to protect the sidewalls of substrate support 135 from plasma gases and to extend the time between maintenance cycles of plasma processing chamber 100.

[0026] In addition, electrode 121 is coupled to power supply 150. Power supply 150 provides electrode 121 with a clamping voltage of approximately 200 volts (V) to approximately 10,000 V. Power supply 150 may also include a system controller for controlling the operation of electrode 121 by directing direct current (DC) to electrode 121 to clamp and release substrate 202.

[0027] During operation, substrate 103 is placed on substrate support 135 within plasma processing chamber 100. Process gases and / or gas mixtures are introduced into chamber body 105 via nozzle 114 from gas distribution disc 160. A vacuum pump system maintains pressure within process space 101 while removing deposited byproducts.

[0028] ESC 122 may include a heater disposed therein and connected to a power source (not shown) for heating the substrate; while the cooling base 129 supporting ESC 122 may include conduits for circulating heat transfer fluid to maintain the temperature of ESC 122 and the substrate 103 disposed thereon. ESC 122 is configured to operate within a temperature range desired by the thermal budget of the device manufactured on substrate 103. For example, ESC 122 may be configured to maintain the substrate 103 at a temperature of about 25 degrees Celsius to about 150 degrees Celsius, such as about 30 degrees Celsius to 110 degrees Celsius.

[0029] The cover ring 130 is positioned on the ESC 122 and along the periphery of the substrate support 135. The cover ring 130 is configured to confine the etching gases to the desired portion of the exposed top surface of the substrate 103, while shielding the top surface of the substrate support 135 from the plasma environment within the plasma processing chamber 100.

[0030] System controller 165 is used to control the program sequence, regulate the airflow from gas distribution plate 160 into plasma processing chamber 100, and other process parameters. System controller 165 includes a central processing unit (CPU), memory, and support circuitry. System controller 165 is used to control the program sequence for processing the substrate. The CPU is a general-purpose computer processor configured for industrial environments to control the processing chamber and its associated subprocessors. The memory (which is typically non-volatile memory) described herein may include random access memory, read-only memory, hard disk drives, or other suitable forms of local or remote digital storage. Support circuitry is typically coupled to the CPU and includes cache memory, clock circuitry, input / output subsystems, power supplies, and combinations thereof. When executed by the CPU, software routines transform the CPU into a dedicated computer (controller) controlling the plasma processing chamber 100 so that the process can be executed according to this invention. Software routines (programs) and data may be encoded and stored in memory used to instruct the processors within the CPU. The CPU-readable software program (or computer instructions) in system controller 165 determines which tasks can be performed by the elements in processing chamber 100. The software program can also be stored and / or executed by a second controller (not shown), such as a processing system (e.g., cluster tool) controller co-located with plasma processing chamber 100. [Substrate Processing Method]

[0031] Figure 2 illustrates a flowchart of a method 200 for patterning a substrate according to some embodiments. Method 200 includes activity 202, in which a gas mixture is supplied on the substrate at a continuous flow rate. The gas mixture may be supplied from a gas distribution disk 160, such as from one or more process gas sources 161, 162, 163, 164. The gas mixture includes halogen-containing gases, boron-containing gases, inert gases, or combinations thereof. In some embodiments, the gas mixture includes a chlorine-containing gas, such as boron trichloride (BCl3).

[0032] The gas mixture may include halogen-containing and argon-containing gases in volume ratios of about 1:1 to about 1:10, such as about 1:3 to about 1:5, or about 1:0 to about 10:1, such as about 3:1 to about 2:1. The halogen-containing gas system is provided at a volumetric flow rate of about 30 sccm to about 300 sccm (such as about 100 sccm to about 200 sccm). Other flow rates are expected depending on the process space size, predetermined substrate pattern, and process chamber design. Inert gases (such as argon) are provided at volumetric flow rates of about 0 sccm to about 900 sccm, such as about 30 sccm to 800 sccm, such as about 100 sccm to 700 sccm, such as about 200 sccm to 600 sccm. In some embodiments, additional gases, such as one or more of O2, H2, C4F6, CH2F2, CF4, and CHF3, C4F8, and C4F6, are provided. The gas mixture is continuously supplied to process space 101 without switching gases or altering the composition of the gas mixture. The gas mixture is delivered at a process pressure of about 1 mT to about 100 mT.

[0033] Method 200 includes activity 204, wherein a first radio frequency (RF) signal is transmitted to an electrode while a gas mixture is supplied at a continuous flow rate to deposit a polymer on a substrate having an oxide-containing portion and a nitride-containing portion. The polymer includes BCln, CClm, CFm, or combinations thereof, wherein n is 3 or less and m is 4 or less. In some embodiments, the oxide-containing portion includes metal oxides, semiconductor oxides, or combinations thereof. In some embodiments, the oxide-containing portion includes aluminum oxide (Al2O3), zirconium oxide (ZrO2), titanium dioxide (TiO2), hafnium dioxide (HfO2), HfAlOx, silicon oxide, germanium oxide, or combinations thereof. In some embodiments, the nitride-containing portion includes silicon nitride (SiNx), titanium nitride (TiNx), gallium nitride (GaN), AlGaN, or combinations thereof. In some implementations, activity 202 of supplying the gas mixture and activity 204 of depositing the polymer on the substrate occur at least partially simultaneously.

[0034] The first radio frequency (RF) signal includes a first RF source power of approximately 50 W to approximately 3000 W from RF source 142, such as approximately 100 W to approximately 1000 W, or such as approximately 500 W to approximately 800 W. The source power is provided at an RF source frequency of approximately 1 MHz to approximately 120 MHz, such as approximately 2 MHz to approximately 60 MHz, or such as approximately 13.56 MHz to approximately 40 MHz. RF source 142 is, for example, coupled to a cover 110 of chamber body 105 via antenna 148. In some embodiments, the first RF signal includes a first RF bias power of approximately 0 W to approximately 500 W, such as approximately 0 W to approximately 100 W, or such as less than 10 W, provided by one or more bias electrode sources 125, 127. In some embodiments, the first RF bias electrode source 125 provides energy at a lower frequency than the second RF bias electrode source 127. First bias electrode source 125 and second bias electrode source 127 are each coupled to an electrode 121 within a substrate support 135, and during method 200, a semiconductor substrate 103 is disposed on a substrate support surface of the substrate support 135. Each bias electrode source is independently tuned relative to each other and relative to a source electrode 142. The first bias electrode source has a frequency of about 2 MHz or lower, such as 1 MHz, and the second bias electrode source has a frequency greater than 2 MHz, such as about 13.56 MHz.

[0035] Method 200 includes activity 206, wherein a second radio frequency (RF) signal is delivered to an electrode while a gas mixture is continuously supplied at a continuous flow rate to selectively etch an oxide-containing portion relative to a nitride-containing portion. The selectivity of etching relative to the oxide-containing portion relative to the nitride-containing portion is about 5 or greater, such as about 10 to about 50, such as about 20 to about 40. In some embodiments, the oxide etch rate is about 0.05 nm / s to about 1 nm / s for the oxide-containing portion. In some embodiments, the nitride etch rate is about 0 nm / s to about 0.02 nm / s for the nitride-containing portion. The second RF signal includes a second RF source power less than the first RF source power. In some embodiments, during activity 206, the RF power supplied to the source electrode 142 is reduced. In some embodiments, during activity 206, the RF power supplied to the source electrode 142 is turned off. In some alternative embodiments, the second RF signal includes delivering a second RF bias power greater than the first RF bias power. In some embodiments, during activity 206, the power of one or more of the RF bias electrode sources is increased or the one or more are turned on.

[0036] Activities 204 and 206 are repeated cyclically. In some embodiments, the duty cycle of the sequence of activity 204 (e.g., a first radio frequency signal) relative to activity 206 (e.g., a second radio frequency signal) is about 5% to about 95%, such as about 30% to about 60%, such as about 40% to about 50%. In one example, activities 204 and 206 constitute a cycle with a frequency of about 10 Hz to about 4000 Hz. In some embodiments, during method 200, the pressure in the process space is maintained at about 1 mTorr to about 100 mTorr.

[0037] Figure 3 illustrates a flowchart of a method 300 for tuning the radio frequency (RF) power of one or more electrodes according to some embodiments. Method 300 includes activity 302, wherein a substrate is positioned on a substrate support disposed in a process space within a process chamber; activity 304, wherein a halogen-containing gas is delivered into the process space at a continuous flow rate; and activity 306, wherein an RF signal is cyclically delivered to a source electrode disposed on the substrate. Cyclicly delivering the RF signal includes activities 308 and 310, in which the RF signal is provided to the source electrode (e.g., electrode 121) for a first time period, and in activity 310, the RF power of the source electrode is reduced and applied for a second time period.

[0038] Figure 4 illustrates a graphical representation 400 of radio frequency (RF) power signals according to some embodiments. Referring back to Figures 2 and 3, period 402 represents a first RF signal for depositing a polymer on a substrate, as described with respect to activity 204 in method 200, and / or providing the RF signal to the electrode described with respect to activity 308 in method 300. Period 404 represents a second RF signal for selective etching, as described with respect to activity 206 in method 200, and / or reducing the first RF power of the electrode associated with activity 310 in method 300. Periods 402 and 404 together constitute operating period 406. Curve 410 illustrates a source RF signal having a first source RF signal state S1 and a second source RF signal state S2, which is transmitted to a source electrode (e.g., source electrode 142). Curve 420 illustrates an RF signal having a first bias RF signal state B1 and a second bias RF signal state B2, which is transmitted to one or more bias electrodes (e.g., electrode 121). As the same gas mixture is continuously flowed into the processing chamber, the power supplied in each radio frequency (RF) signal is transferred to the respective electrodes. As shown in Figure 4, during each cycle of the duty cycle, the high and low RF power of the source RF signal supplied to the source electrodes switches relative to the high and low RF power states of the bias RF signal supplied to one or more bias electrodes. In one example, the switching of the RF signal during cycle 402 begins with a reduction in the power supplied to the source electrodes at the start of the second source RF signal S2 state, which occurs substantially simultaneously with an increase in the power supplied to one or more bias electrodes during cycle 404 attributable to the formation of the second source RF signal B2 state, and vice versa. In some embodiments, the RF signal B1 state may include a power level of 40 W or less, such as 10 W or less, such as 0 to 5 W, or even between 0.1 and 5 W, and the RF signal B2 state may include a power level of approximately 10 W to approximately 500 W, such as approximately 40 W to approximately 100 W. In some embodiments, the radio frequency signal S1 state includes a power level of about 100 W or more, such as about 1000 W to about 3000 W, and the radio frequency signal S2 state includes a power level of about 500 W to about 2000 W.

[0039] In some embodiments, the power delivered during activity 204 (e.g., during period 402) and the power delivered during activity 206 (e.g., during period 404) are alternately applied by the first and second bias electrode sources 125, 127, such that the first bias electrode receives a lower power level (e.g., RF signal B1 state) during period 402 and the first bias electrode (e.g., RF signal B2 state) receives a higher power level during period 404.

[0040] In some embodiments, during activity 204, the first bias electrode source 125 can form a radio frequency signal in state B1 on the first bias electrode disposed in ESC 122, and during activity 204, the second bias electrode source 127 can form a radio frequency signal in state B1 on the first bias electrode disposed in ESC 122. During activity 206, the second bias electrode source 127 can transmit a radio frequency signal in state B2 to the first bias electrode in ESC 122, and the first bias electrode source 125 can transmit a radio frequency signal in state B2 to the first bias electrode. During activities 204 and / or 206, the radio frequency signals provided by the first bias electrode source 125 and the second bias electrode source 127 can be different, such as radio frequency signals provided with different frequencies, phases, voltages, and / or powers.

[0041] In another embodiment, the first and second bias electrode sources 125, 127 alternately apply power delivered during activity 204 (e.g., during cycle 402) and power delivered during activity 206 (e.g., during cycle 404) to the first and second bias electrodes. For example, in activity 204, the first bias electrode source 125 may form a first radio frequency signal in the radio frequency signal B1 state on the first bias electrode disposed in ESC 122, and during activity 204, the second bias electrode source 127 may form a radio frequency signal in the radio frequency signal B2 state on the second bias electrode disposed in ESC 122. In one configuration, the first and second bias electrodes are electrodes positioned adjacent to each other within ESC 122. In activity 206, the second bias electrode source 127 may transmit the radio frequency signal in the radio frequency signal B1 state to the second bias electrode in ESC 122, and the first bias electrode source 125 may transmit the radio frequency signal in the radio frequency signal B2 state.

[0042] In some embodiments of method 200, after performing activity 204, at activity 206, the first bias electrode source 125 may continue to deliver the radio frequency signal B1 state to the first bias electrode while the second bias electrode source 127 switches from the radio frequency signal B1 state to the radio frequency signal B2 state. In another embodiment, both the first and second bias electrode sources may be synchronized such that each electrode source sequentially delivers bias power pulses to the bias electrode, which alternate between the radio frequency signal B1 state and the radio frequency signal B2 state, respectively. For example, in activity 204, the power supplied to the bias electrode is both in a first state (e.g., a lower power state) or an off state; and in activity 206, both are both in a second power state (e.g., an increased power state), or at least in an on state. In some embodiments, the first bias electrode and the second bias electrode may be the same bias electrode, or as described above, they may be separate and different bias electrodes disposed in a substrate support. In some embodiments, the first electrode source 125 delivers lower frequency power relative to the higher frequency power provided by the second electrode source 127.

[0043] Traditional processes utilize alternating pulses to deposit and etch gas components, and are time-consuming due to the need to purge the process space 101 before injecting the alternating gas components, resulting in relatively low yields. Furthermore, in conventional processes, process gas is often wasted when it is not delivered to the process space 101 because it needs to be transferred to the vacuum pump foreline before being introduced into the process space 101 to prevent gas bursts when the gas flow is later reintroduced. Additionally, time is required to stabilize process conditions between gas switching and purge. Without theoretical constraints, it is believed that conventional cyclic processes involve delivering a first gas adsorbed on the substrate surface, and then providing a second gas to activate the surface containing the first gas, causing the adsorbed molecules to react with the substrate and produce undesirable etching of a thin layer on the surface where the adsorbed molecules are disposed.

[0044] The processes described herein do not alternate gas delivery, but instead switch between source power and bias power to control the deposition and etching of material on a substrate. The resulting processes surprisingly provide selectivity in etching oxide portions of the substrate relative to nitride portions. This selectivity is greater than 15, such as greater than 30. Without being bound by theory, it is believed that tuning the source and bias electrodes relative to each other can deposit a thicker polymer on the nitride-containing portion relative to the oxide-containing portion. In some embodiments, deposition period 402 per duty cycle deposits on the nitride-containing portion at a periodic rate of about 0.2 nm / s to about 2 nm / s, such as about 0.4 nm / s to 1.5 nm / s, such as about 0.5 nm / s to 1 nm / s. In some embodiments, less polymer is deposited on the oxide-containing portion per duty cycle deposition period 402 relative to the nitride-containing portion, such as substantially no deposition on the oxide-containing portion. During etching period 404, the bias electrode power is increased, which increases the reactivity of the gas mixture to facilitate etching. The thicker polymer layer on the nitride portion protects the nitride portion and promotes greater selectivity in the etching of the oxide portion during 404 etching. Without theoretical constraints, argon in the gas mixture initiates the etching reaction by bombardment and contributes to the dissociation of BCl₃, thus increasing the concentration of free radicals in the etching process.

[0045] Figure 5 illustrates a substrate before (e.g., 500) and after (e.g., 510) processing using the methods described herein, according to some embodiments. Substrate 500 includes a nitride portion 502 and an oxide portion 504. Any patterned oxide layer relative to the nitride layer can benefit from the methods provided herein. It can be seen that after processing substrate 500 using the methods described herein, the resulting substrate 510 has more etched in the oxide portion 504 relative to the nitride portion 502. The outline of the nitride portion 502 is retained in the resulting substrate 510.

[0046] Implementation may include one or more of the following potential advantages. One or more embodiments of this invention advantageously achieve a process with high oxide selectivity relative to the nitride portion of the substrate during processing, while increasing substrate yield and reducing process gas consumption.

[0047] The embodiments and all functional operations described herein can be implemented in digital electronic circuit systems or computer software, firmware, or hardware, including the structural components disclosed herein and their structural equivalents, or combinations thereof. The embodiments described herein can be implemented as one or more non-transitory computer program products, i.e., one or more computer programs tangibly implemented in a machine-readable storage device for executing or controlling the operation of a data processing device, such as a programmable processor, computer, or multiple processors or computers.

[0048] The processes and logic flows described in this specification can be executed by one or more programmable processors, which execute one or more computer programs to perform functions by manipulating input data and generating outputs. The processes and logic flows can also be executed by dedicated logic circuits, and the device can be implemented as dedicated logic circuits, such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0049] The term "data processing device" encompasses all devices, apparatus, and machines used for processing data, including, for example, programmable processors, computers, or multiple processors or computers. In addition to hardware, the device may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, protocol stacks, database management systems, operating systems, or combinations thereof. Processors suitable for executing computer programs include, for example, general-purpose and special-purpose microprocessors, and any one or more processors of any type of digital computer.

[0050] Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, such as semiconductor memory devices, including erasable programmable read-only memory (EPROM), electronically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and compact optical disc-only memory (CD-ROM) and digital universal optical disc-only memory (DVD-ROM) discs. Processors and memory may be supplemented by or integrated into a dedicated logic circuit system.

[0051] When describing the elements of this case or their exemplary forms or implementations, the articles "a", "an", "the" and "said" are intended to mean that there are one or more elements.

[0052] The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be other elements besides those listed.

[0053] The terms "selective etching" or "selective removal" are intended to broadly describe a process in which one type of material is preferentially removed relative to another type of material, or a process in which material in one region of a substrate is selectively removed relative to one region of the substrate.

[0054] Although the foregoing content pertains to various embodiments of this case, other and further implementations of this case may be designed without departing from the basic scope of this case, and the scope of this invention is determined by the following claims.

[0055] 100: Processing Chamber 101: Processing Space 105: Main body of the chamber 110: Cover 112: Sidewall 113: Substrate in / out port 114: Nozzle 115: Padding 118: Bottom 121: Electrode 122: Electrostatic Chuck 124: Matching Circuit 125: Radio Frequency Power Supply 126: Ground 127: Radio Frequency Power Supply 128: Isolator 129: Cooling Base 130: Cap ring 135: Substrate support 136: Cathode Liner 141: Matching Circuit 142: Antenna power supply 145: Pumping Port 148: Antenna 150: Power Supply 160: Gas distribution plate 161: Process Gas Source 162: Process Gas Source 163: Process Gas Source 164: Process Gas Source 165: System Controller 166: Valve 167: Gas pipeline 200: Method 202: Event 204: Activities 206: Activities 300: Method 302: Event 304: Event 306: Activities 308: Event 310: Activities 400: Graphical representation 402: Cycle 404: Cycle 406: Cycle 410: Curve 420: Curve 500:Substrate 502: Nitride portion 504: Oxide portion 510:Substrate B1: First bias voltage radio frequency signal B2: Second bias RF signal S1: First source radio frequency signal S2: Second source radio frequency signal

[0056] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A method of forming features on a semiconductor substrate, comprising the steps of: supplying a gas mixture to a surface of the substrate at a continuous flow rate; transmitting a first radio frequency (RF) signal to an electrode while supplying the gas mixture at a continuous flow rate to deposit a polymer layer on the surface of the substrate, wherein the surface of the substrate includes an oxide-containing portion and a nitride-containing portion; and transmitting a second radio frequency (RF) signal to the electrode while continuously supplying the gas mixture at the continuous flow rate to selectively etch the oxide-containing portion relative to the nitride-containing portion, wherein the first radio frequency (RF) signal is in a high-power state when the second radio frequency (RF) signal is in a low-power state, and the first radio frequency (RF) signal is in a low-power state when the second radio frequency (RF) signal is in a high-power state.

2. The method as described in claim 1, wherein the first radio frequency signal includes a first radio frequency source power of about 500 W to about 3000 W, and the second radio frequency signal includes a second radio frequency source power less than the first radio frequency source power.

3. The method as described in claim 2, wherein the electrode is a cover of a process chamber disposed on the substrate.

4. The method as described in claim 1, wherein the first radio frequency signal includes a first radio frequency bias power of about 0 W to about 500 W, and the second radio frequency signal includes a second radio frequency bias power greater than the first radio frequency bias power.

5. The method as described in claim 4, wherein the electrode is an electrode disposed within a substrate support on which the substrate is disposed, and the gas mixture is continuously supplied.

6. The method as described in claim 4 further comprises the step of: transmitting a third and a fourth radio frequency signal, each comprising a third and a fourth radio frequency bias power, the third and fourth radio frequency signals being provided to a bias electrode.

7. The method as claimed in claim 6, wherein the first and second radio frequency signals comprise a frequency of about 2 MHz to about 40 MHz, and the third and fourth radio frequency signals comprise a frequency of about 10 MHz to about 100 MHz.

8. The method as claimed in claim 1, wherein the first radio frequency signal includes a first radio frequency source frequency of about 1 MHz to about 40 MHz, and the second radio frequency signal includes a second radio frequency of about 1 MHz to about 40 MHz.

9. The method as described in claim 1, wherein a duty cycle for transmitting the first radio frequency signal is between about 40% and about 60% relative to transmitting the second radio frequency signal.

10. The method as described in claim 1, wherein the gas mixture comprises a chlorine-containing gas and a boron-containing gas.

11. The method as described in claim 1, wherein the oxide-containing portion comprises a metal oxide.

12. The method as described in claim 1, wherein the gas mixture comprises a chlorine-containing gas and an argon-containing gas in a volume ratio of about 1:1 to about 1:

10.

13. The method as claimed in claim 12, wherein the gas mixture comprises: BCl3 supplied at a gas flow rate of about 30 sccm to about 300 sccm; and argon supplied at a gas flow rate of about 0 sccm to about 900 sccm.

14. A method of processing a semiconductor substrate, comprising the steps of: positioning a substrate on a substrate support disposed in a process space of a process chamber; flowing a chlorine-containing gas into the process space at a continuous flow rate; and cyclically transmitting a radio frequency (RF) signal to a source electrode disposed on the substrate, the substrate being disposed on the substrate support, wherein the step of cyclically transmitting the RF signal comprises the steps of: supplying a first radio frequency (RF) signal to the source electrode at a first RF power for a first time period; reducing the first RF power supplied to the source electrode to a second RF power for a second time period; and transmitting a bias power to a bias electrode coupled to the substrate support; wherein the step of transmitting the bias power is performed substantially simultaneously with reducing the first RF power to the second RF power, wherein the first RF signal is in a high power state when the bias power is in a low power state, and the first RF signal is in a low power state when the bias power is in a high power state.

15. The method as described in claim 14, wherein the chlorine-containing gas flows into the process space at the continuous flow rate while cyclically transmitting radio frequency signals to the source electrode.

16. The method of claim 14, wherein providing the first radio frequency signal to the source electrode is configured to form a polymer layer on a substrate, wherein the polymer layer is selectively formed on a nitride portion of the substrate.

17. The method as described in claim 14, wherein the first radio frequency power is reduced to the second radio frequency power and the bias power is delivered to the bias electrode to selectively etch an oxide portion relative to a nitride portion disposed on a surface of the substrate.

18. A method of processing a semiconductor substrate, comprising the steps of: positioning the substrate on a substrate support, the substrate support being disposed in a process space of a process chamber; flowing a chlorine-containing gas into the process space at a continuous flow rate; and cyclically transmitting a radio frequency (RF) signal to a source electrode disposed on the substrate, wherein the step of cyclically transmitting the RF signal to the source electrode comprises the steps of: supplying a biased radio frequency (RF) power to a bias electrode coupled to the substrate support for a first time period; and increasing the biased RF power to the bias electrode for a second time period, wherein during the first time period, the RF signal is in a high-power state and the biased RF power is in a low-power state, and during the second time period, the RF signal is in a low-power state and the biased RF power is in a high-power state.

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