Systems and methods for providing an HF RF signal to an upper electrode extension

Abstract

Systems and methods for controlling a processing rate at an edge region of a plasma chamber are described. One of the systems includes a first radio frequency (RF) generator that generates a first RF signal. A first matching circuit outputs a first modified RF signal upon receiving the first RF signal. The system includes a plasma chamber having a substrate support and an upper electrode extension. The first impedance matching circuit provides the first modified RF signal to the substrate support. The upper electrode is coupled to a ground potential or to a floating potential. The system includes a second RF generator that generates a second RF signal. A second impedance matching circuit outputs a second modified RF signal upon receiving the second RF signal. The second impedance matching circuit provides the second modified RF signal to the upper electrode extension.

Description

SYSTEMS AND METHODS FOR PROVIDING AN HF RF SIGNAL TO AN UPPER ELECTRODE EXTENSIONFIELD

[0001] The embodiments described in the present disclosure relate to systems and methods for providing a high frequency (HF) radio frequency (RF) signal to an upper electrode extension.BACKGROUND

[0002] The background description provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0003] In a plasma tool, a radio frequency (RF) generator, a match, and a plasma chamber are provided. The RF generator is coupled via the match to the plasma chamber. Within the plasma chamber, a semiconductor wafer is placed to be processed. The RF generator generates an RF signal and RF power of the RF signal is supplied via the match to the plasma chamber. The RF power is used to process the substrate. However, there are inefficiencies in processing the substrate.

[0004] It is in this context that embodiments described in the present disclosure arise.SUMMARY

[0005] Embodiments of the disclosure provide systems and methods for providing a high frequency (HF) radio frequency (RF) signal to an upper electrode extension. It should be appreciated that the present embodiments can be implemented in numerous ways, e.g., a process, an apparatus, a system, a piece of hardware, or a method on a computer-readable medium. Several embodiments are described below.

[0006] In an embodiment, a system for controlling a processing rate at an edge region of a plasma chamber is described. The system includes a first RF generator that generates a first RF signal and a first impedance matching circuit coupled to the first RF generator to receive the first RF signal. The first impedance matching circuit outputs a first modified RF signal upon receiving the first RF signal. The system includes a plasma chamber having a substrate support, an upper electrode, and an upper electrode extension. The upper electrode extension surrounds the upper electrode. The first impedance matching circuit is coupled to the substrate support to provide the first modified RF signal to the substrate support. The upper electrode is coupled to a ground potential. The system includes a second RF generator that generates a second RF signaland a second impedance matching circuit coupled to the second RF generator to receive the second RF signal. The second impedance matching circuit outputs a second modified RF signal upon receiving the second RF signal. The second impedance matching circuit is coupled to the upper electrode extension to provide the second modified RF signal to the upper electrode extension.

[0007] In an embodiment, a system for controlling a processing rate at an edge region of a plasma chamber is described. The system includes a first RF generator that generates a first RF signal and a first impedance matching circuit coupled to the first RF generator to receive the first RF signal. The first impedance matching circuit outputs a first modified RF signal upon receiving the first RF signal. The system includes a plasma chamber having a substrate support, an upper electrode, and an upper electrode extension. The upper electrode extension surrounds the upper electrode. The first impedance matching circuit is coupled to the substrate support to provide the first modified RF signal to the substrate support. The upper electrode is coupled to a floating potential. The system includes a second RF generator that generates a second RF signal and a second impedance matching circuit coupled to the second RF generator to receive the second RF signal. The second impedance matching circuit outputs a second modified RF signal upon receiving the second RF signal. The second impedance matching circuit is coupled to the upper electrode extension to provide the second modified RF signal to the upper electrode extension.

[0008] In one embodiment, a method for controlling a processing rate at an edge region of a plasma chamber is described. The method includes generating a first RF signal, receiving the first RF signal to output a first modified RF signal, and providing the first modified RF signal to a substrate support of a plasma chamber. The plasma chamber includes an upper electrode coupled to a ground potential or a floating potential. The plasma chamber includes an upper electrode extension surrounding the upper electrode. The method includes generating a second RF signal, receiving the second RF signal to output a second modified RF signal, and providing the second modified RF signal to the upper electrode extension.

[0009] Some advantages of the herein described systems and methods include reducing chances of gas hole light up. By coupling an upper electrode to a ground potential or a floating potential and by providing RF power to a plasma chamber via the upper electrode extension, chances of the igniting one or more process gases within one or more gas outlets of a gas distribution plate (GDP) are reduced. When the one or more process gases are ignited within the one or more gas outlets, the gas hole light up occurs.

[0010] Further advantages of the herein described systems and methods include providing control of plasma density within the plasma chamber. By controlling an amount of RFpower supplied to the upper electrode extension, the plasma density is controlled. By controlling the plasma density, a rate of processing a substrate is controlled. For example, when the amount of RF power supplied to the upper electrode extension is increased, the plasma density is increased, and the rate of processing the substrate increases. On the other hand, when the amount of RF power supplied to the upper electrode extension is decreased, the plasma density is decreased, and the rate of processing the substrate decreases. There is no need to change edge hardware, such as the upper electrode extension, to control the plasma density. When the plasma density increases, an amount of RF voltage of an RF signal and a frequency of the RF signal that is supplied to a lower electrode of the plasma chamber decreases to save power. Also, in addition to the control of plasma density, a voltage of plasma sheath formed within the plasma chamber can be controlled by controlling RF voltage that is supplied to an edge ring.

[0011] Some other aspects will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The embodiments are understood by reference to the following description taken in conjunction with the accompanying drawings.

[0013] Figure 1 is a diagram of an embodiment of a system to illustrate an upper electrode extension (U.E.E.) that is coupled to a high frequency (HF) radio frequency (RF) generator.

[0014] Figure 2 is a diagram of an embodiment of an upper electrode assembly to illustrate that instead of grounding an upper electrode, the upper electrode is floated.

[0015] Figure 3 is a diagram of an embodiment of a system to illustrate uniformity in supply of power to the upper electrode extension.

[0016] Figure 4 is a diagram of an embodiment of a system to illustrate that RF power of an RF signal is supplied by a low frequency (LF) RF generator to an edge ring of a plasma chamber to increase a density of plasma in an edge region and RF power of an HF RF signal is used to tune the density.

[0017] Figure 5A is an embodiment of a graph to illustrate a relationship between RF power that is delivered to a tunable edge sheath (TES) of plasma within the edge region and an amount of power that is supplied by an RF signal generated by the HF RF generator.

[0018] Figure 5B is an embodiment of a graph to illustrate that there is a decrease in a frequency and an amplitude of voltage of an RF signal supplied by the LF RF generator with an increase in an amount of power supplied by an RF signal that is generated by the HF RF generator.

[0019] Figure 6 is an embodiment of a graph to illustrate that a rate at which a substrate is etched increases at a central region and at an edge region increases with an increase in density of plasma at the edge region.DETAILED DESCRIPTION

[0020] The following embodiments describe systems and methods for providing a high frequency (HF) radio frequency (RF) signal to an upper electrode extension. It will be apparent that the present embodiments may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present embodiments.

[0021] Figure 1 is a diagram of an embodiment of a system 100 to illustrate an upper electrode extension (U.E.E.) 102 that is coupled to a high frequency (HF) RF generator 104, such as a y megahertz (MHz) RF generator, where y is a positive integer. The HF RF generator 104 or another HF RF generator is not coupled to a substrate support 106. The system 100 includes a host computer 108, a low frequency (LF) RF generator 110, an impedance matching circuit 112, another impedance matching circuit 114, and a plasma chamber 116. The system 100 also includes a gas source system 118, a valve system 119, a gas supply line system 120, and a driver and motor system 121.

[0022] The host computer 108 includes a processor 122 and a memory device 123. The plasma chamber 116 includes the substrate support 106, an upper electrode assembly 105, the upper electrode extension 102, an insulator ring 124, and another insulating ring 126. The insulator ring 124 surrounds the upper electrode assembly 105. For example, an inner diameter of the insulator ring 124 is greater than an outer diameter of the upper electrode assembly 105. As another example, the insulator ring 124 is located in the same horizontal plane as that of the upper electrode assembly 105. To illustrate, a horizontal axis passes through the insulator ring 124 and the upper electrode assembly 105. Also, the upper electrode extension 102 is a ring that surrounds the insulator ring 124 and the insulator ring 126 surrounds the upper electrode extension 102. For example, an inner diameter of the upper electrode extension 102 is greater than an outer diameter of the insulator ring 124 and an inner diameter of the insulator ring 126 is greater than an outer diameter of the upper electrode extension 102. As another example, the upper electrode extension 102 is located in the horizontal plane as that of the insulator rings 124 and 126. To illustrate, the horizontal axis passes through the upper electrode extension 102 and the insulator rings 124 and 126.

[0023] Also, a gap 128 is a space formed between the substrate support 106 and the upper electrode assembly 105and between the substrate support 106 and the upper electrode extension 102. For example, the gap 128 includes a main region 129 and an edge region 131.The main region 129 is formed between a central portion 135 of the substrate support 106 and the upper electrode assembly 105, and the edge region 131 is formed between an edge portion 137 of the substrate support 106 and the upper electrode extension 102. For example, the edge portion 137 surrounds the main portion 135 and the edge region 131 surrounds the main region 129. To illustrate, a diameter of the edge portion 137 is greater than a diameter of the main portion 135 and a diameter of the edge region 131 is greater than a diameter of the main region 129. The upper electrode assembly 105includes an upper electrode 130 and a gas distribution plate (GDP) 132. The upper electrode 130 is located below the GDP 132. For example, a top surface 107 of the upper electrode 130 is fixed to, such as attached to or screwed to, a bottom surface 109 of the GDP 132. As another example, the upper electrode 130 is located at a horizontal level below a horizontal level at which the GDP 132 is located.

[0024] An example of the host computer 108 includes a desktop computer or a laptop computer or a smart phone or a tablet or a controller. Examples of the processor 122 include a microprocessor, a microcontroller, a central processing unit (CPU), an application specific integrated circuit (ASIC), and a programmable logic device (PLD). Examples of the memory device 123 include a read-only memory and a random access memory.

[0025] An example of the LF RF generator 110 is an RF generator having a low frequency, such as a low operating frequency. For example, the LF RF generator 110 is an x kilohertz (kHz) RF generator, where x is a positive integer. The low operating frequency is sometimes referred to herein as a low frequency of operation. Examples of the low operating frequency include a frequency in kHz, such as a frequency ranging from and including 10 kHz to 99 kHz. To illustrate, the low operating frequency is 100 kHz or 400 kHz. An example of the HF RF generator 104 is an RF generator having a high frequency, such as a high operating frequency. To illustrate, the HF RF generator 104 includes a small capacity power supply that is capable of generating RF power, of an RF signal, ranging from and including 1 kilowatt (kW) peak to 10 kW peak. To further illustrate, the HF RF generator 104 is not a large capacity RF generator having a power supply that is capable of generating RF power of an RF signal, ranging from and including 15 kW peak to 17 kW peak. The high operating frequency is sometimes referred to herein as a high frequency of operation. An example of the high operating frequency includes a frequency of 60 MHz, such as a frequency ranging from and including 54 MHz to 63 MHz.

[0026] An example of an impedance matching circuit, described herein, is an impedance matching network or impedance match. To illustrate, the impedance matching circuit includes a network of capacitors and inductors that are coupled to each other.

[0027] As an example, the substrate support 106 is an electrostatic chuck (ESC). Within the substrate support 106, a lower electrode is embedded. As an example, the lower electrode is made from a conductive material, such as silicon or silicon carbide or aluminum or a combination of two or more thereof. Also, as an example, the upper electrode 130 is fabricated from the conductive material. Moreover, as an example, the upper electrode extension 102 is fabricated from the conductive material. As an example, each of the insulator rings 124 or 126 is fabricated from a dielectric material, such as quartz.

[0028] The gas source system 118 has one or more gas containers and each gas container stores a process gas, such as a fluorine containing gas or an oxygen containing gas or a hydrogen containing gas or a combination of two or more thereof. The gas supply line system120 includes one or more gas supply lines and each gas supply line is connected to a respective one of the gas containers. The valve system 119 includes one or more gas valves and each of the gas valves is coupled to a respective one of the gas supply lines. The driver and motor system121 includes one or more drivers and one or more electric motors. An example of a driver includes one or more transistors that are coupled to each other. Each of the drivers is coupled to a respective one of the electric motors and each of the electric motors is coupled to a respective one of the gas valves.

[0029] The processor 122 is coupled to the driver and motor system 121, which is coupled to the valve system 119. The gas source system 118 is coupled to the valve system 119, which is coupled via the gas supply line system 120 to the GDP 132.

[0030] The processor 122 is also coupled via a transfer cable 133 to the HF RF generator 104, which is coupled via an RF cable 134 to an input 136 of the impedance matching circuit 114. An example of a transfer cable, as described herein, includes a cable that enables a serial transfer of data, or a parallel transfer of data, or transfer of data using a Universal Serial Bus (USB) protocol. An output 138 of the impedance matching circuit 114 is coupled via an RF transmission line 140 to the upper electrode extension 102.

[0031] The upper electrode 130 is coupled to, such as connected to, a ground potential, such as a zero potential. For example, the upper electrode 130 is coupled to a top wall 152 of the plasma chamber 116 via the GDP 132 or a side wall 154 of the plasma chamber 116, and the walls 152 and 154 are grounded. In the example, the GDP 132 is attached to, such as fixed to or screwed to, the top wall 152, and the top surface 107 of the upper electrode 130 is attached to, such as fixed to or screwed to, the bottom surface 109 of the GDP 132. To illustrate, the upper electrode 130 is not connected to an RF generator via an impedance matching circuit.

[0032] The processor 122 is coupled via a transfer cable 142 to the LF RF generator 110, which is coupled via an RF cable 144 to an input 146 of the impedance matching circuit112. An output 148 of the impedance matching circuit 112 is coupled via an RF transmission line 152 to the lower electrode of the substrate support 106.

[0033] It should be noted that there is no HF RF generator, such as the large capacity HF RF generator, coupled to the impedance matching circuit 112. For example, the large capacity HF RF generator is not coupled to an input of the impedance matching circuit 112. When the HF RF generator is not coupled to the impedance matching circuit 112, life of the substrate support 106 increases.

[0034] The plasma chamber 116 has the top wall 152, the side wall 154, and a bottom wall 156 to form a housing of the plasma chamber 116. The top wall 152 is adjacent to, above, and connects to the side wall 154. The side wall 154 is adjacent to, above, and connects to the bottom wall 156. Within the side wall 154 is a dielectric window 158 and coupled to the dielectric window 158 is an optical sensor 160, such as an optical emission spectrometer. The processor 122 is coupled to the optical emission spectrometer 160. The processor 122 is also coupled to the memory device 123.

[0035] The processor 122 generates and sends a recipe signal 166 to the LF RF generator 110, and sends another recipe signal 168 to the HF RF generator 104. For example, a recipe signal, as described herein, sent to an RF generator indicates, such as includes, frequency and power information, of an RF signal to be generated by the RF generator. To illustrate, the recipe signal, includes peak power of the RF signal to be generated by the RF generator and a frequency of the RF signal.

[0036] Upon receiving the recipe signal 166, a processor of the LF RF generator 110 stores the frequency and power information, indicated by the recipe signal 166, within a memory device of the LF RF generator 110. Similarly, upon receiving the recipe signal 168, a processor of the HF RF generator 104 stores the frequency and power information, indicated by the recipe signal 168, within a memory device of the HF RF generator 104.

[0037] A substrate S, such as a semiconductor wafer, is placed on top substrate a top surface of the substrate support 106. The substrate S has a central region 101 and an edge region 103. The edge region 103 surrounds the center region 101 and is adjacent to the center region 101. For example, the center region 101 is located below the main region 129 and the edge region 103 is located below the edge region 131. As another example, the center region 101 is located directly above the central portion 135 and the edge region 103 is located directly above the edge portion 137.

[0038] The processor 122 generates and sends a trigger signal to the LF RF generator 110 and to the HF RF generator 104. Upon receiving the trigger signal, the LF RF generator 110 generates, such as produces, an RF signal 170 having the low frequency. The RF signal 170 issupplied from the LF RF generator 110 via the RF cable 144 to the input 146. Upon receiving the RF signal 170, the impedance matching circuit 112 matches an impedance of a load coupled to the output 148 with an impedance of a source coupled to the input 146 to modify an impedance of the RF signal 170 to output a modified RF signal 172 having the low frequency. An example of the load coupled to the output 148 includes the RF transmission line 150 and the plasma chamber 116, and an example of the source coupled to the input 146 includes the RF cable 144 and the LF RF generator 110. The modified RF signal 172 is transferred from the output 148 via the RF transmission line 152 to the lower electrode.

[0039] Also, upon receiving the trigger signal, the HF RF generator 104 generates an RF signal 174 having the high frequency. The RF signal 174 is supplied from the HF RF generator 104 via the RF cable 134 to the input 136. Upon receiving the RF signal 174, the impedance matching circuit 114 matches an impedance of a load coupled to the output 138 with an impedance of a source coupled to the input 136 to modify an impedance of the RF signal 174 to output a modified RF signal 176 having the high frequency. An example of the load coupled to the output 138 includes the RF transmission line 140 and the plasma chamber 116, and an example of the source coupled to the input 136 includes the RF cable 134 and the HF RF generator 104. The modified RF signal 176 is transferred from the output 138 via the RF transmission line 140 to the upper electrode extension 102.

[0040] In addition to controlling the RF generators 104 and 110 by sending the trigger signal, the processor 122 sends one or more control signals to the driver and motor system 121. Upon receiving the one or more control signals, the driver and motor system 121 operates to control the valve system 119 to open one or more of the gas valves. When the one or more gas valves are open, one or more of the process gases flow from the gas source system 118 via the valve system 119 and one or more of the gas lines of the gas supply line system 120 to the GDP 132. Upon receiving the one or more process gases, the GDP 132 has one or more gas outlets, such as gas outlets 206A and 206B (Figure 2), that transfer the one or more process gases to the upper electrode 130. The upper electrode 130 has one or more through holes, such as through holes 208A and 208B (Figure 2), that output the one or more process gases to the gap 128. For example, each of the one or more through holes of the upper electrode 130 has a diameter of 0.5 millimeters (mm). As another example, each of the one or more through holes of the upper electrode 130 has a diameter less than 0.5 mm, such as a diameter ranging from and including 0.3 mm to 0.49 mm. When one or more process gases are supplied simultaneously with the modified RF signals 172 and 176, plasma is stricken or maintained within the gap 128 and the plasma processes the substrate S. For example, the substrate S is etched, or one or more materials are deposited on the substrate S, or the substrate S is cleaned, or a combination thereof.

[0041] By coupling the upper electrode 130 and the GDP 132 to ground, there is less risk of gas hole light up. For example, when the one or more process gases are supplied via the GDP 132 and the upper electrode 130 to the gap 128, the one or more process gases are not subject to any RF power via the upper electrode 130. This reduces, such as eliminates, chances of the one or more process gases in the one or more gas outlets of the GDP 132 from combusting from the RF power. Also, when the HF RF generator 104 is of the small capacity, chances of the gas hole light up are reduced.

[0042] It should also be noted that there is no supply of the one or more process gases from the upper electrode extension 102 to the gap 128. For example, there is no gas source that is coupled to the upper electrode extension 102. This non-coupling of the gas source of the upper electrode extension 102 reduces chances of the gas hole light up.

[0043] During a time period in which the one or more process gases and the modified RF signals 172 and 176 are supplied to the plasma chamber 116, the optical sensor 160 measures an intensity of light emitted by the plasma formed within the edge region 131 to generate a measurement signal 180 and provides the measurement signal 180 to the processor 122. The measurement signal 180 indicates the intensity of light emitted by plasma.

[0044] The processor 122 determines density of the plasma based on the measurement signal 180, and determines whether the density is within a predetermined density range stored in the memory device 123. For example, the processor 122 accesses a table stored within the memory device 123 listing correspondences, such as one-to-one relationships or links or unique relationships, between multiple values of plasma density and multiple values of intensity of light. The table is accessed to identify a value of density of the plasma corresponding to the intensity of light indicated within the measurement signal 180. The processor 122 determines whether the value of density that is identified is within the predetermined density range.

[0045] Upon determining that the value of density identified is within the predetermined density range, the processor 122 determines not to modify the RF power of the RF signal 174. On the other hand, in response to determining that the value of density identified is outside the predetermined density range, the processor 122 determines to modify the frequency and power information of the recipe signal 168 used to generate the RF signal 174 to output frequency and power information of another recipe signal 184. For example, the processor 122 modifies, such as increases or decreases, the peak power of the RF signal 174 to output peak power of an RF signal 182 to be generated by the HF RF generator 104. The processor 122 generates the recipe signal 184 indicating, such as including, the frequency and power information of the RF signal 182, and sends the recipe signal 184 to the HF RF generator 104. In the recipe signal 184, thefrequency of the RF signal 182 to be generated is the same as, such as equal to, the frequency of the RF signal 174.

[0046] When the recipe signal 184 is received, the processor of the HF RF generator 104 stores the frequency and power information indicated by the recipe signal 184 within the memory device 123. The processor 122 again sends the trigger signal to the HF RF generator 104 immediately after sending the frequency and power information indicated by the recipe signal 184 to the HF RF generator 104. Upon receiving the trigger signal, the HF RF generator generates, such as produces, the RF signal 182 having the frequency and power information indicated by the recipe signal 184.

[0047] The impedance matching circuit 114 receives the RF signal 182 and matches an impedance of the load coupled to the output 138 with an impedance of the load coupled to the input 136 to modify an impedance of the RF signal 182 to provide a modified RF signal 186, having the high frequency, at the output 138. The modified RF signal 186 is sent from the impedance matching circuit 114 to the upper electrode extension 102.

[0048] Upon receiving the modified RF signal 186 simultaneously with the reception of the modified RF signal 172 and the one or more process gases, impedance of the plasma formed within the edge region 131 is modified. When the impedance of the plasma formed within the edge region 131 is modified, the optical sensor 160 senses an intensity of light emitted by the plasma within the edge region 131 to generate a measurement signal 188.

[0049] Upon receiving the measurement signal 188 indicating the intensity of light emitted by the plasma within the edge region 131, the processor 122 determines density of the plasma based on the measurement signal 188, and determines whether the density is within the predetermined density range. For example, the processor 122 accesses the table from the memory device 123 to identify value of density of the plasma corresponding to the intensity of light indicated with the measurement signal 188. The processor 122 determines whether the value of density that is identified is within the predetermined density range.

[0050] In response to determining that the value of density identified is within the predetermined density range, the processor 122 determines not to modify the RF power of the RF signal 182 and continue to control the HF RF generator 104 to generate, such as produce, the RF signal 182. For example, the processor 122 continues to control the HF RF generator 104 to generate the RF signal 182 by not modifying the recipe signal 184. When the recipe signal 184 is not modified, the processor 122 does not generate another recipe signal based on the modification and does not send the other recipe signal to the HF RF generator 184 to continue to control the HF RF generator 104 to generate the RF signal 182. On the other hand, upon determining that the value of density identified is outside the predetermined density range, theprocessor 122 modifies the RF power of the RF signal 182 in the same manner in which the RF power of the RF signal 174 is modified. In this manner, the processor 122 continues to control the HF RF generator 104 to modify RF power of an RF signal output from the HF RF generator 104 until it is determined that a value of intensity of plasma indicated within a measurement signal received from the optical sensor 160 is within the predetermined density range.

[0051] It should be noted that with an increase in an RF power of an RF signal that is generated by the HF RF generator 104, there is an increase in plasma density within the edge region 131. For example, when RF power of the RF signal 182 is greater than RF power of the RF signal 174, there is an increase in the plasma density within the edge region 131. On the other hand, when RF power of the RF signal 182 is less than RF power of the RF signal 174, there is a decrease in the plasma density within the edge region 131. When the plasma density increases within the edge region 131, the substrate S, such as an edge of the substrate S, is processed in a more efficient manner. For example, a lesser amount of voltage of an RF signal is to be output by the LF RF generator 110 when the plasma density increases.

[0052] In one embodiment, the processor 122 modifies the RF power of the RF signal 166 based on the measurement signal 188. For example, upon determining that the value of density of plasma corresponding to the value of intensity of light indicated by the measurement signal 188 is within the predetermined density range, the processor 122 determines to modify, such as increase or decrease, RF power of the RF signal 170 to generate another recipe signal 190. To illustrate, when the value of density of plasma corresponding to the value of intensity of light indicated by the measurement signal 188 is greater than the value of density of plasma corresponding to the value of intensity of light indicated by the measurement signal 180 and is within the predetermined density range, the processor 122 controls the LF RF generator 110 to decrease RF power and / or the low frequency of the RF signal 170 to generate, such as produce, another RF signal 192. To further illustrate, the low frequency of the RF signal 192 is less than the low frequency of the RF signal 170 or the amount of peak power of the RF signal 192 is less than the amount of peak power of the 170 or a combination thereof. In this manner, the lower amount of power of the RF signal 192 is applied compared to the amount of power of the RF signal 170 when there is an increase in the plasma density. As another illustration, when the value of density of plasma corresponding to the value of intensity of light indicated by the measurement signal 188 is less than the value of density of plasma corresponding to the value of intensity of light indicated by the measurement signal 180 and is within the predetermined density range, the processor 122 controls the LF RF generator 110 to increase RF power of the RF signal 170 to generate the RF signal 192. Continuing with the example, the processor 122 sends the recipe signal 190 to the LF RF generator 110. To illustrate, the recipe signal 190indicates, such as includes, frequency and power information, such as a peak power and the low frequency of the RF signal 192 to be generated by the LF RF generator 110. Upon receiving the recipe signal 190, the processor of the LF RF generator 110 stores the frequency and power information, indicated by the recipe signal 190, within the memory device of the LF RF generator 110. The processor 122 sends the trigger signal to the LF RF generator 110 immediately after sending the recipe signal 190 to the LF RF generator 110. Upon receiving the trigger signal, the processor of the LF RF generator 110 controls the power supply of the LF RF generator 110 to generate the RF signal 192. The RF signal 192 is supplied from the LF RF generator 110 via the RF cable 144 to the input 146. Upon receiving the RF signal 192, the impedance matching circuit 112 matches an impedance of the load coupled to the output 148 with an impedance of the source coupled to the input 146 to modify an impedance of the RF signal 192 to output a modified RF signal 194 having the low frequency. The modified RF signal 194 is transferred from the output 148 via the RF transmission line 152 to the lower electrode. In this manner, there is a decrease in RF power that is supplied by the LF RF generator 110 when there is an increase in density of plasma within the edge region 131.

[0053] Figure 2 is a diagram of an embodiment of an upper electrode assembly 200 to illustrate that instead of grounding the upper electrode 130, the upper electrode 130 is floated, such is coupled to a floating potential. The upper electrode assembly 200 includes the GDP 132, the upper electrode 130, a gasket 202, and an insulator layer 203. As an example, the insulator layer 203 is fabricated from a dielectric material, such as aluminum oxide or aluminum nitride or a combination thereof. As an example, the gasket 202 is fabricated from a conductive material, such as aluminum or an alloy of aluminum. The gasket 202 is situated between the upper electrode 130 and the GDP 132. For example, the gasket 202 is attached to, such as fixed to or screwed to, the bottom surface 109 of the GDP 132 to be located adjacent to the top surface 107 of the upper electrode 130. For example, there is no layer between the top surface 107 of the upper electrode 130 and a bottom surface 204 of the gasket 202. As another example, there is no space between the top surface 107 of the upper electrode 130 and the bottom surface 204 of the gasket 202 and the top surface 107 of the upper electrode 130 adjoins the gasket 202. When the gasket 202 is located adjacent to the top surface 107 of the upper electrode 130, the gasket 202 is coupled to the upper electrode 130. As another example, the gasket 202 is attached, such as fixed to or screwed to, the top surface 107 of the upper electrode 130 to be located adjacent to the top surface 107 of the upper electrode 130.

[0054] The insulator layer 203 is fabricated on or at a top surface 206 of the GDP 132 to be coupled to the GDP 132. When the GDP 132 is coupled to the insulator layer 203, instead of to the ground potential, the GDP 132 and the upper electrode 130 are floated. When the upperelectrode 130 is coupled to the floating potential, there is less risk of lighting up of the one or more process gases in the one or more through holes of the upper electrode 130 compared to one in which the upper electrode 130 is coupled to one or more RF generators for receiving RF power from the one or more RF generators. When the upper electrode 130 is coupled to the floating potential, there is an increase in a density of plasma within the etch region 131 (Figure 1) compared to when the upper electrode is coupled to the ground potential. When the density increases, a lower amount of RF power of an RF signal supplied by the LF RF generator 110 (Figure 1) is used to achieve a process rate, such as an etch rate or deposition rate or a combination thereof, of processing the substrate S. The amount of RF power of the RF signal supplied by the LF RF generator 110 is less when the upper electrode is coupled to the floating potential compared to an amount of RF power of the RF signal supplied by the LF RF generator 110 when the upper electrode is coupled to the ground potential and the process rate achieved when the upper electrode is coupled to the floating potential is within a predetermined range from, such as equal to, a process rate achieved when the upper electrode 130 is coupled to the ground potential.

[0055] In an embodiment, the insulator layer 203 is absent from the upper electrode assembly 200. Also, in the embodiment, the bottom surface 109 of the GDP 132 is anodized, such as for example, with an oxide layer, and is attached, such as fixed or screwed, to the gasket 202 for the upper electrode 130 to be at the floating potential. For example, an anodic layer is formed at or under the bottom surface 109 of the GDP 132 via an electrochemical process to anodize the bottom surface 109 of the GDP 132. The anodized bottom surface of the GDP 132 is attached, such as fixed or screwed, to the gasket 202.

[0056] In one embodiment, instead of the insulator 203, a conductive disc, which is fabricated from the conductive material, is used to ground the upper electrode 130. For example, the conductive disc is coupled to the GDP 132 in the same manner as that of the gasket 202 to couple the GDP 132 and the upper electrode 130 to the ground potential. The conductive disc is coupled to the top wall 152 (Figure 1) or the side wall 154 of the plasma chamber 106 (Figure 1).

[0057] Figure 3 is a diagram of an embodiment of a system 300 to illustrate uniformity in supply of power to the upper electrode extension 102. The system 300 includes the HF RF generator 104, the impedance matching circuit 114, and an upper electrode extension 302. The upper electrode extension 302 is an example of the upper electrode extension 102 (Figure 1). An example of the upper electrode extension 302 is a ring having an inner diameter 304 and an outer diameter 306. A body 308 of the upper electrode extension 302 extends from the inner diameter 304 to the outer diameter 306.

[0058] The RF transmission line 140 is coupled at a connection point 310, such as a connector or a splitter or a divider, to multiple RF connections 312, 314, and 316. An example of an RF connection includes one or more RF straps or one or more RF cables or a combination thereof. For example, an RF connection includes an RF strap coupled to another RF strap. To illustrate, an RF strap is fabricated from a conductive material, such as copper. As another example, an RF connection includes an RF strap that is coupled to an RF cable.

[0059] Each RF connection 312, 314, and 316 is coupled to a respective one of multiple pins 318, 320 and 322. For example, the RF connection 312 is connected to the pin 318, the RF connection 314 is connected to the pin 320, and the RF connection 316 is connected to the pin 322. Each pin 318, 320 and 322 is fabricated from a conductive material, such as aluminum or an alloy of aluminum.

[0060] The body 308 has a top surface 324. The top surface 324 faces the top wall 152 (Figure 1). Also, the body 308 has a bottom surface 326, which is located in a direction opposite to the direction of the top surface 324. For example, the bottom surface 326 does not face the top wall 152 and faces the substrate support 106 (Figure 1) via the edge region 131.

[0061] Also, each pin 318, 320 and 322 is connected to the top surface 324 and is sometimes referred to herein as a point. For example, holes 328, 330, and 332 are formed within portions PR1, PR2, and PR3 of the top surface 324. To illustrate, the holes 328, 330, and 332 are drilled into the top surface 324 to enable the pins 318, 320 and 322 to extend partially into the body 308. For example, the holes 328, 330, and 332 do not extend completely along a height of the body 308 to allow the pins 318, 320 and 322 to extend partially along the height from the top surface 324. Rather, the holes 328, 330, and 332 extend within a portion of the height of the body 308. To further illustrate, the holes 328, 330, 332 are formed at vertices of an equilateral triangle on the top surface 324 to be uniformly located across the top surface 324. As another illustration, the hole 328 is formed by drilling the portion PR1, the hole 330 is formed by drilling the portion PR2, and the hole 332 is formed by drilling the portion PR3. It should be noted that the height of the body 308 is measured along a y-axis. The y-axis is perpendicular to an x-axis and a z-axis, and the z-axis is illustrated in Figure 1.

[0062] A modified RF signal, such as the modified RF signal 176 or 186, is transferred via the RF transmission line 140 to the connection point 310. RF power of the modified RF signal 176 is split at the connection point 310 to form modified RF signals 334, 336, and 338. Each modified signal 334, 336, and 338 has the high frequency. The modified RF signal 334 is supplied via the RF connection 312 and the pin 318 to a first portion of the body 308, the modified RF signal 336 is supplied via the RF connection 314 and the pin 320 to a second portion of the body 308, and the modified RF signal 338 is supplied via the RF connection 316and the pin 322 to a third portion of the body 308. The first, second, and third portions of the body 308 form the body 308. In this manner, RF power of the modified RF signal is divided equally at the connection point 310 to be supplied symmetrically, such as uniformly, across the body 308. For example, an amount of power applied by the modified RF signal 334 is within a predetermined range from, such as equal to, an amount of power applied by the modified RF signal 336 and the amount of power applied by the modified RF signal 336 is within the predetermined range from, such as equal to, an amount of power applied by the modified RF signal 338. When the RF power is supplied symmetrically across the body 308, the edge of the substrate S is processed in a uniform manner.

[0063] In one embodiment, instead of three holes, any other number of holes, such as a number of holes ranging between two and eight, are formed on the top surface 324 and the holes are formed in a uniform manner. For example, two holes are formed on the top surface 324 and are located 180° apart across the top surface 324. As another example, seven holes are formed on the top surface 324 and a distance between any two adjacent one of the holes is the same.

[0064] Figure 4 is a diagram of an embodiment of the system 400 to illustrate that RF power of an RF signal is supplied by an LF RF generator 402 to an edge ring 404 of a plasma chamber 408 to increase a density of plasma in the edge region 131 and RF power of the RF signal 182 is used to tune the density. The system 400 is the same as the system 100 (Figure 1), except that the system 400 includes an HF RF generator 410, an impedance matching circuit 412, the LF RF generator 402, and an impedance matching circuit 412. Moreover, the plasma chamber 408 is the same as the plasma chamber 116 (Figure 1), except that the plasma chamber 408 includes the edge ring 404. For example, at least a portion of the edge ring 404 is located directly below at least a portion of the upper electrode extension 102. The edge ring 404 surrounds the substrate support 106. For example, an inner diameter of the edge ring 404 is greater than a diameter of the substrate support 106.

[0065] The HF RF generator 410 is an RF generator having the high frequency and is similar to the HF RF generator 104 in terms of capacity. To illustrate, the HF RF generator 410 includes a small capacity power supply that is capable of generating RF power, of an RF signal, ranging from and including 1 kW peak to 10 kW peak. To further illustrate, the HF RF generator 410 is not the large capacity RF generator having a power supply that is capable of generating RF power of an RF signal, ranging from and including 15 kW peak to 17 kW peak. The impedance matching circuit 412 has the input 146, another input 414, and the output 148. The LF RF generator 402 is an RF generator having the low frequency.

[0066] The LF RF generator 110 is coupled via a transfer cable 416 to the LF RF generator 402. The HF RF generator 104 is coupled to the input 414 of the impedance matchingcircuit 412 via an RF cable 420 and is coupled to the HF RF generator 410 via a transfer cable 422. The output 148 of the impedance matching circuit 412 is coupled via the RF transmission line 150 to the lower electrode. Also, the HF RF generator 410 is coupled via the RF cable 134 to the input 136 of the impedance matching circuit 114.

[0067] The LF RF generator 402 is coupled via an RF cable 424 to an input 426 of the impedance matching circuit 414. An output 428 of the impedance matching circuit 414 is coupled via an RF transmission line 430 to the edge ring 404.

[0068] The substrate S is placed on the top surface of the substrate support 106 within the plasma chamber 408. Also, the one or more process gases are supplied via the one or more gas outlets of the GDP 132 and the upper electrode 130 to the gap 128. It should be noted that the edge region 131 is formed between the upper electrode extension 102 and the edge ring 404.

[0069] The LF RF generator 402 is synchronized, in operation, with an operation of, the LF RF generator 110. For example, upon receiving the recipe signal 166 from the processor 122, the processor of the LF RF generator 110 sends the recipe signal 166 via the transfer cable 416 to a processor of the LF RF generator 402. The processor of the LF RF generator 402 stores the frequency and power information indicated within the recipe signal 166, within a memory device of the LF RF generator 402. Upon receiving the trigger signal from the processor 122, the processor of the LF RF generator 110 sends the trigger signal via the transfer cable 416 to the processor of the LF RF generator 402. In response to receiving the trigger signal, the processor of the LF RF generator 402 controls a power supply of the LF RF generator 402 to generate an RF signal 434 having one or more parameters of the RF signal 434 that are synchronized with one or more parameters of the RF signal 170. For example, a phase of the RF signal 434 is within a predetermined phase range from, such as the same as, a phase of the RF signal 170. As another example, a frequency of the RF signal 434 is within a predetermined frequency range from, such as equal to, the low frequency of the RF signal 170. As yet another example, an amplitude, of the RF signal 434 is within a predetermined amplitude range, such as equal to, an amplitude, of the RF signal 170. An example of an amplitude, as described herein, is a peak-to- peak amplitude or a peak amplitude. Examples of parameters, as described herein, include phase, frequency, and amplitude.

[0070] Upon receiving the RF signal 434 at the input 426, the impedance matching circuit 412 matches an impedance of a load coupled to the output 428 with an impedance of a source coupled to the input 426 to modify an impedance of the RF signal 434 to provide a modified RF signal 436 at the output 428. An example of the source coupled to the input 426 includes the RF cable 424 and the LF RF generator 402, and an example of the load coupled to the output 428 includes the RF transmission line 430 and the plasma chamber 408. The modifiedRF signal 436 is supplied from the output 428 via the RF transmission line 430 to the edge ring 404.

[0071] Upon receiving the recipe signal 168 and the trigger signal, the HF RF generator 104 generates the RF signal 174. The RF signal 174 is supplied from the HF RF generator 104 via the RF cable 420 to the input 414. The impedance matching circuit 412 receives the RF signals 170 and 174 at the inputs 146 and 414, and matches an impedance of a load coupled to the output 148 of the impedance matching circuit 412 with an impedance of a source coupled to the inputs 146 and 414 to modify impedances of the RF signals 170 and 174 to provide a modified RF signal 438, having the low frequency, at the output 148 of the impedance matching circuit 412. An example of the load coupled to the output 148 of the impedance matching circuit 412 includes the RF transmission line 110 and the plasma chamber 408, and an example of the source coupled to the inputs 146 and 414 includes the RF cables 144 and 420 and the RF generators 110 and 104. The modified RF signal 438 has the low frequency and is supplied via the RF transmission line 150 to the lower electrode to process the substrate S.

[0072] Also, upon receiving the recipe signal 168, the processor of the HF RF generator 104 sends the recipe signal 168 via the transfer cable 422 to a processor of the HF RF generator 410. When the recipe signal 168 is received, the processor of the HF RF generator 410 stores the frequency and power information indicated within the recipe signal 168 in a memory device of the HF RF generator 410. Also, upon receiving the trigger signal, the processor of the HF RF generator 104 sends the trigger signal via the transfer cable 422 to the processor of the HF RF generator 410. In response to receiving the trigger signal, the processor of the HF RF generator 410 controls a power supply of the HF RF generator 410 to generate an RF signal 440 having one or more parameters that are synchronized to one of more parameters of the RF signal 174. For example, a phase of the RF signal 440 is within a predetermined phase range from, such as the same as, a phase of the RF signal 174. As another example, a frequency of the RF signal 440 is within a predetermined frequency range from, such as equal to, the low frequency of the RF signal 174. To illustrate, the RF signal 440 has the high frequency. As yet another example, an amplitude, of the RF signal 440 is within a predetermined amplitude range, such as equal to, an amplitude, of the RF signal 174.

[0073] The RF signal 440 is sent from the HF RF generator 410 via the RF cable 134 to the input 136 of the impedance matching circuit 114. Upon receiving the RF signal 440, the matching circuit 114 matches an impedance of the load coupled to the output 138 with an impedance of a source coupled to the input 136 to modify an impedance of the RF signal 440 to provide a modified RF signal 442 at the output 138. The modified RF signal 442 has the highfrequency. The modified RF signal 442 is supplied from the output 138 via the RF transmission line 140 to the upper electrode extension 102.

[0074] When the modified RF signals 438, 436, and 442 are provided to the plasma chamber 408 in addition to the one or more process gases, plasma is stricken or generated within the plasma chamber 408. When the plasma is stricken or generated within the plasma chamber 408, the optical sensor 160 generates the measurement signal 180.

[0075] The processor 122 receives the measurement signal 180 from the optical sensor 160 and modifies the recipe signal 168 to the recipe signal 184 based on the measurement signal 180 in the same manner as that described above with reference to Figure 1. Upon receiving the recipe signal 184, the processor of the HF RF generator 104 controls the power supply of the HF RF generator 104 to generate the RF signal 182. The RF signal 182 is sent from the HF RF generator 184 to the input 414 of the impedance matching circuit 412. Upon receiving the RF signals 170 and 182, the impedance matching circuit 412 matches an impedance of the load coupled to the output 148 with an impedance of the source coupled to the inputs 146 and 414 to modify an impedances of the RF signals 170 and 182 to provide a modified RF signal 446 at the output 148. The modified RF signal 446 is sent from the output 148 via the RF transmission line 150 to the lower electrode.

[0076] Also, the processor of the HF RF generator 104 sends the recipe signal 184 via the transfer cable 422 to the HF RF generator 410. The processor of the HF RF generator 104 stores the power and frequency information indicated by the recipe signal 184 within the memory device of the HF RF generator 104. The processor 122 sends the trigger signal to the HF RF generator 104 immediately after sending the frequency and power information indicated by the recipe signal 184 to the HF RF generator 104. Upon receiving the trigger signal, the processor of the HF RF generator 104 sends the trigger signal via the transfer cable 422 to the HF RF generator 410. In response to receiving the trigger signal, the processor of the HF RF generator 410 controls the power supply of the HF RF generator 410 to generate an RF signal 448 having one or more parameters that are synchronized to one or more parameters of the RF signal 182 in the same manner in which the one or more parameters of the RF signal 440 are synchronized to the one or more parameters of the RF signal 174. The RF signal 448 is sent from the HF RF generator 410 via the RF cable 134 to the input 136. Upon receiving the RF signal 448, the impedance matching circuit 114 matches an impedance of the load coupled to the output 138 with an impedance of the source coupled with input 136 to modify an impedance of the RF signal 448 to provide a modified RF signal 450 at the output 138. The modified RF signal 450 is supplied from the output 138 via the RF transmission line 140 to the upper electrode extension 102.

[0077] When the modified RF signals 450 and 446 are supplied to the plasma chamber 408 in addition to the modified RF signal 436 and the one more process gases, the optical sensor 160 generates the measurement signal 188 and provides the measurement signal 188 to the processor 122. The processor 122 determines whether the value of density of plasma within the edge region 131 corresponding to the value of light intensity indicated by the measurement signal 188 is within the predetermined density range in the same manner as that described above with reference to Figure 1. Upon determining that the value of density of plasma corresponding to the value of light intensity, within the edge region 131, indicated by the measurement signal 188 is within the predetermined density range, the processor 122 determines not to modify the frequency and power information within the recipe signal 184. On the other hand, in response to determining that the value of density of plasma corresponding to the value of light intensity, within the edge region 131, indicated by the measurement signal 188 is outside the predetermined density range, the processor 122 determines to modify the frequency and power information within the recipe signal 184. In this manner, the processor 122 controls the LF RF generator 104 to modify RF power of an RF signal generated by the HF RF generator 104 to further modify RF power of an RF signal generated by the HF RF generator 410 until the value of density of plasma within the edge region 131 is within the predetermined density range.

[0078] In the embodiment, described above with reference to Figure 1, in which the processor 122 controls the LF RF generator 110 to modify the RF power of the RF signal 166 based on the measurement signal 188 to generate the RF signal 192, the LF RF generator 110 sends the RF signal 192 via the RF cable 144 to the input 146. Upon receiving the RF signals 182 and 192, the impedance matching circuit 412 matches an impedance of the load coupled to the output 148 with an impedance of the source coupled to the inputs 146 and 414 to modify an impedance of the RF signal 192 to output a modified RF signal 446 having the low frequency. The modified RF signal 446 is transferred from the output 148 via the RF transmission line 150 to the lower electrode. In this manner, there is a decrease in RF power that is supplied by the LF RF generator 110 when there is an increase in density of plasma within the edge region 131.

[0079] Moreover, in the embodiment, the LF RF generator 402 is synchronized, in operation, with an operation of the LF RF generator 110. For example, upon receiving the recipe signal 190 from the processor 122, the processor of the LF RF generator 110 sends the recipe signal 190 via the transfer cable 416 to the processor of the LF RF generator 402. The processor of the LF RF generator 402 stores the frequency and power information indicated within the recipe signal 190, within the memory device of the LF RF generator 402. Upon receiving the trigger signal from the processor 122, the processor of the LF RF generator 110 sends the trigger signal via the transfer cable 416 to the processor of the LF RF generator 402. In response toreceiving the trigger signal, the processor of the LF RF generator 402 controls the power supply of the LF RF generator 402 to generate an RF signal 452 having one or more parameters of the RF signal 452 that are synchronized with one or more parameters of the RF signal 192. For example, a phase of the RF signal 452 is within a predetermined phase range from, such as the same as, a phase of the RF signal 192. As another example, a frequency of the RF signal 452 is within a predetermined frequency range from, such as equal to, the low frequency of the RF signal 192. As yet another example, an amplitude, of the RF signal 452 is within a predetermined amplitude range, such as equal to, an amplitude, of the RF signal 192.

[0080] Upon receiving the RF signal 452 at the input 426, the impedance matching circuit 414 matches an impedance of the load coupled to the output 428 with an impedance of the source coupled to the input 426 to modify an impedance of the RF signal 452 to provide a modified RF signal 454 at the output 428. The modified RF signal 454 is supplied from the output 428 via the RF transmission line 430 to the edge ring 404.

[0081] It should be noted that when there is an increase in density of plasma within the edge region 131, there is a decrease in RF power of the RF signal 452 compared to RF power of the RF signal 434. This increases efficiency in processing the substrate S when a lower amount of RF power of the RF signal 452 is used. On the other hand, when there is a decrease in density of plasma within the edge region 131, there is an increase in RF power of the RF signal 452 compared to RF power of the RF signal 434.

[0082] Figure 5A is an embodiment of a graph 500 to illustrate a relationship between RF power that is delivered to a tunable edge sheath (TES) of plasma within the edge region 131 (Figure 1) and an amount of power that is supplied by an RF signal generated by the HF RF generator 104 (Figures 1 and 4). The graph 500 plots the delivered RF power to the TES on a y- axis and the amount of power supplied by the RF signal that is generated by the HF RF generator 104 on an x-axis. The graph 500 includes a plot 502. As illustrated by the plot 502, with an increase in the amount of power supplied by the RF signal that is generated by the HF RF generator 104 there is an increase in the RF power that is delivered to the TES. With the increase in the RF power delivered to the TES, there is an increase in density of plasma the edge region 131. On the other hand, with a decrease in the amount of power supplied by the RF signal that is generated by the HF RF generator 104 there is a decrease in the RF power that is delivered to the TES. With the decrease in the RF power delivered to the TES, there is a decrease in density of plasma the edge region 131. As such, plasma density within the edge region 131 is tuned, such as increased or decreased.

[0083] Figure 5B is an embodiment of a graph 510 to illustrate that there is a decrease in a frequency and an amplitude of voltage of an RF signal supplied by the LF RF generator 110(Figures 1 and 4) with an increase in an amount of power supplied by an RF signal that is generated by the HF RF generator 104 (Figures 1 and 4). The graph 510 includes a plot 512 of a frequency of the RF signal generated by the LF RF generator 110 on a y-axis and the amount of power supplied by the RF signal that is generated by the HF RF generator 104 on an x-axis. The x-axis of the graph 510 is the same as the x-axis of the graph 500.

[0084] With the increase in the amount of power that is supplied by the RF signal generated by the HF RF generator 104, there is an increase in density of plasma in the edge region 131. Also, with the increase in the amount of power supplied by the RF signal generated by the HF RF generator 104, there is a decrease in a frequency of the RF signal that is generated by the LF RF generator 110 and / or a decrease in an amount of voltage of the RF signal generated by the LF RF generator 110. As such, by controlling the HF RF generator 104 to increase an amount of power of an RF signal generated by the HF RF generator 104, there is an increase in density of plasma in the edge region 131. Also, when the density in the edge region 131 increases, the LF RF generator 110 can be operated more efficiently to decrease an amount of RF power and decrease a frequency of the RF signal that is output from the LF RF generator 110.

[0085] Figure 6 is an embodiment of a graph 600 to illustrate that a rate at which the substrate S is etched increases at the central region 101 and at the edge region 103 (Figure 1) increases with an increase in density of plasma at the edge region 103. The graph 600 plots an etch rate on a y-axis and a diameter of the substrate S on an x-axis. The graph 600 includes a plot 602, another plot 604, yet another plot 606, and another plot 608. The plot 602 is generated when an amount of RF power of an RF signal supplied by the HF RF generator 104 (Figure 1) is 0 Watts (W). Also, the plot 604 is generated when an amount of RF power of an RF signal supplied by the HF RF generator 104 is 500 Watts, the plot 606 is generated when an amount of RF power of an RF signal supplied by the HF RF generator 104 is 1000 Watts, and the plot 608 is generated when an amount of RF power of an RF signal supplied by the HF RF generator 104 is 2000 Watts. As illustrated from the plots 602, 604, 606, and 608, within increase in the amount of RF power output from the HF RF generator 104, there is an increase in density of plasma within the edge region 131, and in etch rate of etching the substrate S at the central and edge regions 101 and 103 increases. Also, with an increase in the amount of RF power output from the HF RF generator 104, uniformity in processing the substrate S across a top surface of the substrate S remains substantially the same. The top surface of the substrate S faces the gap 128 (Figure 1).

[0086] Embodiments, described herein, may be practiced with various computer system configurations including hand-held hardware units, microprocessor systems,microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The embodiments, described herein, can also be practiced in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a computer network.

[0087] In some embodiments, a controller is part of a system, which may be part of the above-described examples. The system includes semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). The system is integrated with electronics for controlling its operation before, during, and after processing of a semiconductor wafer or substrate. The electronics is referred to as the “controller,” which may control various components or subparts of the system. The controller, depending on processing requirements and / or a type of the system, is programmed to control any process disclosed herein, including a delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with the system.

[0088] Broadly speaking, in a variety of embodiments, the controller is defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). The program instructions are instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a process on or for a semiconductor wafer. The operational parameters are, in some embodiments, a part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0089] The controller, in some embodiments, is a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller is in a “cloud” or all or a part of a fab host computer system, which allows for remote access for wafer processing. The controller enables remote access to the system to monitor current progress of fabrication operations, examines a history of past fabrication operations, examines trends or performance metrics from a plurality offabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process.

[0090] In some embodiments, a remote computer (e.g. a server) provides process recipes to the system over a computer network, which includes a local network or the Internet. The remote computer includes a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of settings for processing a wafer. It should be understood that the settings are specific to a type of process to be performed on a wafer and a type of tool that the controller interfaces with or controls. Thus as described above, the controller is distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the fulfilling processes described herein. An example of a distributed controller for such purposes includes one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at a platform level or as part of a remote computer) that combine to control a process in a chamber.

[0091] Without limitation, in various embodiments, a plasma system, described herein, includes a plasma etch chamber, a deposition chamber, a spin-rinse chamber, a metal plating chamber, a clean chamber, a bevel edge etch chamber, a physical vapor deposition (PVD) chamber, a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, an atomic layer etch (ALE) chamber, an ion implantation chamber, a track chamber, or any other semiconductor processing chamber that is associated or used in fabrication and / or manufacturing of semiconductor wafers.

[0092] It is further noted that although the above-described operations are described with reference to a parallel plate plasma chamber, e.g., a capacitively-coupled plasma (CCP) chamber, etc., in some embodiments, the above-described operations apply to other types of plasma chambers, e.g., a plasma chamber including an inductively coupled plasma (ICP) reactor, a transformer coupled plasma (TCP) reactor, conductor tools, dielectric tools, a plasma chamber including an electron cyclotron resonance (ECR) reactor, etc. For example, an X MHz RF generator, a Y MHz RF generator, and a Z MHz RF generator are coupled to an inductor within the ICP plasma chamber.

[0093] As noted above, depending on a process operation to be performed by the tool, the controller communicates with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport thatbring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0094] With the above embodiments in mind, it should be understood that some of the embodiments employ various computer-implemented operations involving data stored in computer systems. These computer-implemented operations are those that manipulate physical quantities.

[0095] Some of the embodiments also relate to a hardware unit or an apparatus for performing these operations. The apparatus is specially constructed for a special purpose computer. When defined as a special purpose computer, the computer performs other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose.

[0096] In some embodiments, the operations, described herein, are performed by a computer selectively activated, or are configured by one or more computer programs stored in a computer memory, or are obtained over a computer network. When data is obtained over the computer network, the data may be processed by other computers on the computer network, e.g., a cloud of computing resources.

[0097] One or more embodiments, described herein, can also be fabricated as computer- readable code on a non-transitory computer-readable medium. The non-transitory computer- readable medium is any data storage hardware unit, e.g., a memory device, etc., that stores data, which is thereafter read by a computer system. Examples of the non-transitory computer- readable medium include hard drives, network attached storage (NAS), ROM, RAM, compact disc-ROMs (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (CD-RWs), magnetic tapes and other optical and non-optical data storage hardware units. In some embodiments, the non- transitory computer-readable medium includes a computer-readable tangible medium distributed over a network-coupled computer system so that the computer-readable code is stored and executed in a distributed fashion.

[0098] Although some method operations, described above, were presented in a specific order, it should be understood that in various embodiments, other housekeeping operations are performed in between the method operations, or the method operations are adjusted so that they occur at slightly different times, or are distributed in a system which allows the occurrence of the method operations at various intervals, or are performed in a different order than that described above.

[0099] It should further be noted that in an embodiment, one or more features from any embodiment described above are combined with one or more features of any other embodimentwithout departing from a scope described in various embodiments described in the present disclosure.

[0100] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

CLAIMS1. A system for controlling a processing rate at an edge region of a plasma chamber, comprising: a first radio frequency (RF) generator configured to generate a first RF signal; a first impedance matching circuit coupled to the first RF generator to receive the first RF signal, wherein the first impedance matching circuit is configured to output a first modified RF signal upon receiving the first RF signal; a plasma chamber including a substrate support, an upper electrode, and an upper electrode extension, wherein the upper electrode extension surrounds the upper electrode, wherein the first impedance matching circuit is coupled to the substrate support to provide the first modified RF signal to the substrate support, wherein the upper electrode is coupled to a ground potential; a second RF generator configured to generate a second RF signal; a second impedance matching circuit coupled to the second RF generator to receive the second RF signal, wherein the second impedance matching circuit is configured to output a second modified RF signal upon receiving the second RF signal, wherein the second impedance matching circuit is coupled to the upper electrode extension to provide the second modified RF signal to the upper electrode extension.

2. The system of claim 1, wherein each of the first RF signal and the first modified RF signal has a low frequency and each of the second RF signal and the second modified RF signal has a high frequency, wherein the low frequency is a kilohertz frequency, and the high frequency is a megahertz frequency.

3. The system of claim 1, wherein the first impedance matching circuit is not coupled to a third RF generator that is configured to operate at a frequency of the second RF generator.

4. The system of claim 1, wherein the upper electrode is not coupled to an RF generator to be coupled to the ground potential.

5. The system of claim 1, wherein the upper electrode is coupled to a conductive gasket to be coupled to the ground potential.

6. The system of claim 1, wherein the plasma chamber includes an upper electrode assembly having the upper electrode and a gas distribution plate, wherein the gas distribution plate is located above the upper electrode, wherein the gas distribution plate is configured to receive one or more process gases for outputting the one or more process gases to the upper electrode and a gap between the upper electrode and the substrate support.

7. The system of claim 1, wherein the second impedance matching circuit is coupled to the upper electrode extension at a plurality of points to supply RF power symmetrically to the plurality of points.

8. The system of claim 1, wherein the second RF generator is a small capacity RF generator and the second RF signal has a power amount ranging from and including 1 kilowatts to 10 kilowatts.

9. The system of claim 1, further comprising a host computer coupled to the second RF generator, wherein the host computer is configured to send a recipe signal to the second RF generator to control the second RF generator to generate a third RF signal, wherein the host computer is configured to: receive a measurement indicating a first density of plasma within the plasma chamber when the second RF signal is supplied; determine whether the first density is within a predetermined range; receive a measurement indicating a second density of plasma within the plasma chamber when the third RF signal is supplied; determine whether the second density is within the predetermined range; control the second RF generator to continue to generate the third RF signal in response to determining that the second density is within the predetermined range and the first density is outside the predetermined range.

10. A system for controlling a processing rate at an edge region of a plasma chamber, comprising: a first radio frequency (RF) generator configured to generate a first RF signal; a first impedance matching circuit coupled to the first RF generator to receive the first RF signal, wherein the first impedance matching circuit is configured to output a first modified RF signal upon receiving the first RF signal; a plasma chamber including a substrate support, an upper electrode, and an upper electrode extension, wherein the upper electrode extension surrounds the upper electrode, wherein the first impedance matching circuit is coupled to the substrate support to provide the first modified RF signal to the substrate support, wherein the upper electrode is coupled to a floating potential; a second RF generator configured to generate a second RF signal;a second impedance matching circuit coupled to the second RF generator to receive the second RF signal, wherein the second impedance matching circuit is configured to output a second modified RF signal upon receiving the second RF signal, wherein the second impedance matching circuit is coupled to the upper electrode extension to provide the second modified RF signal to the upper electrode extension.

11. The system of claim 10, wherein the upper electrode is not coupled to an RF generator and is not coupled to a ground potential to be floated.

12. The system of claim 10, wherein the plasma chamber includes an upper electrode assembly having the upper electrode and a gas distribution plate, wherein the upper electrode is coupled to a conductive gasket and the gas distribution plate is coupled to an insulator layer to float the upper electrode.

13. The system of claim 10, wherein each of the first RF signal and the first modified RF signal has a low frequency and each of the second RF signal and the second modified RF signal has a high frequency, wherein the low frequency is a kilohertz frequency, and the high frequency is a megahertz frequency.

14. The system of claim 10, wherein the first impedance matching circuit is not coupled to a third RF generator that is configured to operate at a frequency of the second RF generator.

15. The system of claim 10, wherein the plasma chamber includes an upper electrode assembly having the upper electrode and a gas distribution plate, wherein the gas distribution plate is located above the upper electrode, wherein the gas distribution plate is configured to receive one or more process gases for outputting the one or more process gases to the upper electrode and a gap between the upper electrode and the substrate support.

16. The system of claim 10, wherein the second impedance matching circuit is coupled to the upper electrode extension at a plurality of points to supply RF power symmetrically to the plurality of points.

17. The system of claim 10, wherein the second RF generator is a small capacity RF generator and the second RF signal has a power amount ranging from and including 1 kilowatts to 10 kilowatts.

18. The system of claim 10, further comprising a host computer coupled to the second RF generator, wherein the host computer is configured to send a recipe signal to the second RF generator to control the second RF generator to generate a third RF signal, wherein the host computer is configured to:receive a measurement indicating a first density of plasma within the plasma chamber when the second RF signal is supplied; determine whether the first density is within a predetermined range; receive a measurement indicating a second density of plasma within the plasma chamber when the third RF signal is supplied; determine whether the second density is within the predetermined range; control the second RF generator to continue to generate the third RF signal in response to determining that the second density is within the predetermined range and the first density is outside the predetermined range.

19. A method for controlling a processing rate at an edge region of a plasma chamber, comprising: generating a first radio frequency (RF) signal; receiving the first RF signal to output a first modified RF signal; providing the first modified RF signal to a substrate support of a plasma chamber, wherein the plasma chamber includes an upper electrode coupled to a ground potential or a floating potential, wherein the plasma chamber includes an upper electrode extension surrounding the upper electrode; generating a second RF signal; receiving the second RF signal to output a second modified RF signal; and providing the second modified RF signal to the upper electrode extension.

20. The method of claim 19, wherein each of the first RF signal and the first modified RF signal has a low frequency and each of the second RF signal and the second modified RF signal has a high frequency, wherein the low frequency is a kilohertz frequency, and the high frequency is a megahertz frequency.

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