System and method for etching high aspect ratio structures

Abstract

A method for etching a laminate is described. This method includes the steps of etching a first nitrogen-containing layer of the laminate by applying a non-metallic gas, and stopping the application of the non-metallic gas when it is determined that a first oxide layer has been reached. The first oxide layer is located beneath the first nitrogen-containing layer. This method further includes the step of etching the first oxide layer by applying a metal-containing gas. The application of the metal-containing gas is stopped when it is determined that a second nitrogen-containing layer will be reached. The second nitrogen-containing layer is located beneath the first oxide layer. This method includes the step of etching the second nitrogen-containing layer by applying a non-metallic gas.

Description

Technical Field

[0001] Embodiments described in the present disclosure relate to a system and method for etching a high aspect ratio structure.

Background Art

[0002] The background art described in this specification is for presenting the content of the present disclosure generally. The inventions of the inventors whose names are currently listed are not expressly or implicitly recognized as prior art to the present disclosure in the scope described in this background art column and in aspects of the description that do not fall within the prior art at the time of filing.

[0003] A radio frequency (RF) generator generates an RF signal and supplies the RF signal to a plasma reactor via a matcher. The plasma reactor has a semiconductor wafer to be etched when an RF signal is supplied to the plasma reactor and an etching gas is supplied. However, a desired etching rate for the semiconductor wafer is not achieved while the semiconductor wafer is being etched.

[0004] Embodiments described in the present disclosure have arisen in such a situation.

Summary of the Invention

[0005] Embodiments of the present disclosure provide an apparatus, a method, and a computer program for etching a high aspect ratio structure. It should be recognized that the present embodiments can be implemented in several ways (e.g., a method in a process, an apparatus, a system, hardware, or a computer-readable medium). Some embodiments are described below.

[0006] Metal-containing chemicals are used to etch high aspect ratio structures, such as dynamic random access memory stacks. These chemicals can improve mask residue during etching of high aspect ratio features. However, when metal-containing chemicals are used to etch nitrogen-containing layers in high aspect ratio structures, under-etching of the nitrogen-containing layer or etch stops in the nitrogen-containing layer can occur. For example, the nitrogen-containing layer may be etched at or not etched at a predetermined etching rate.

[0007] Embodiments describe a method for etching a laminate. This method includes the steps of etching a first nitrogen-containing layer of the laminate by applying a non-metallic gas and stopping the application of the non-metallic gas when it is determined that a first oxide layer has been reached. The first oxide layer is located beneath the first nitrogen-containing layer. This method further includes the step of etching the first oxide layer by applying a metal-containing gas. The application of the metal-containing gas is stopped when it is determined that a second nitrogen-containing layer will be reached. The second nitrogen-containing layer is located beneath the first oxide layer. This method includes the step of etching the second nitrogen-containing layer by applying a non-metallic gas.

[0008] In one embodiment, a controller for etching a stack is described. The controller includes a processor that controls the application of a nonmetallic gas to etch a first nitrogen-containing layer of the stack. The processor then stops applying the nonmetallic gas when it determines that it has reached a first oxide layer. The first oxide layer is located beneath the first nitrogen-containing layer. The processor further controls the etching of the first oxide layer by applying a metal-containing gas. The processor then stops applying the metal-containing gas when it determines that it will reach a second nitrogen-containing layer. The second nitrogen-containing layer is located beneath the first oxide layer. The processor further controls the etching of the second nitrogen-containing layer by applying a nonmetallic gas. The controller also includes a memory device connected to the processor.

[0009] In this embodiment, a plasma system for etching a laminate is described. The plasma system includes a first gas source for storing a metal-containing gas. The plasma system further includes a second gas source for storing a non-metallic gas. The plasma system includes a plasma chamber connected to the first gas source via a first gas line and to the second gas source via a second gas line. The plasma system also includes a host computer connected to the first and second gas lines. The host computer controls the etching of the first nitrogen-containing layer of the laminate by applying the non-metallic gas. The host computer then stops applying the non-metallic gas when it determines that it has reached the first oxide layer. The host computer further controls the etching of the first oxide layer by applying the metal-containing gas. The host computer stops applying the metal-containing gas when it determines that it will reach the second nitrogen-containing layer. The host computer then controls the etching of the second nitrogen-containing layer by applying the non-metallic gas.

[0010] Some advantages of the systems and methods for etching high aspect ratio structures described herein include etching the nitrogen-containing layer of the high aspect ratio structure using a non-metallic gas and etching the oxide layer of the high aspect ratio structure using a metal-containing gas. The oxide layer is etched at a predetermined rate using the metal-containing gas. By etching the nitrogen-containing layer using a non-metallic gas instead of a metal-containing gas, a predetermined etching rate for etching high aspect ratio structures is achieved.

[0011] A further advantage of the systems and methods for etching high aspect ratio structures described herein is that the parameter levels of a primary radio frequency (RF) signal and a secondary RF signal are pulsed at a predetermined rate. An example of a primary RF signal is a low-frequency (LF) RF signal, and an example of a secondary RF signal is a high-frequency (HF) RF signal. By achieving a predetermined rate, passivation deposition is driven more towards the top of the feature than towards the bottom. By driving deposition in this way, the possibility of under-etching of nitrogen-containing layers in high aspect ratio structures is reduced.

[0012] Several other embodiments will become apparent from the embodiments for carrying out the invention described below, in conjunction with the attached drawings. [Brief explanation of the drawing]

[0013] The embodiments will be understood by referring to the following description in conjunction with the attached drawings.

[0014] [Figure 1] Diagram illustrating an embodiment of a high aspect ratio contact (high aspect ratio) structure.

[0015] [Figure 2A] Figure 1 shows an embodiment of the high aspect ratio structure, illustrating the processing of the high aspect ratio structure.

[0016] [Figure 2B] Figure 2A shows an embodiment of the high aspect ratio structure, illustrating further processing of the high aspect ratio structure.

[0017] [Figure 2C] Figure 2B shows an embodiment of the high aspect ratio structure, illustrating further processing of the high aspect ratio structure.

[0018] [Figure 2D] Figure 2C shows an embodiment of the high aspect ratio structure, illustrating further processing of the high aspect ratio structure.

[0019] [Figure 2E] High aspect ratio structure diagram showing further processing of the high aspect ratio structure of FIG. 2D.

[0020] [Figure 3] Embodiment diagram of a system showing the application of chemical substances A and B to the high aspect ratio structure of FIG. 1.

[0021] [Figure 4A] Embodiment diagram of a system showing the use of an optical sensor to determine the time to switch between the application of chemical substance A and the application of chemical substance B.

[0022] [Figure 4B] Embodiment diagram of a system showing the use of a light intensity range for etching different layers of the high aspect ratio structure of FIG. 1.

[0023] [Figure 5A] Embodiment of a graph showing the pulsing of a primary RF signal versus time t.

[0024] [Figure 5B] Embodiment of a graph showing the pulsing of a secondary RF signal versus time t.

[0025] [Figure 6] Embodiment diagram of a system showing a low frequency (LF) radio frequency (RF) generator and a high frequency (HF) RF generator for inter-level pulses during the application of chemical substances A and B.

MODE FOR CARRYING OUT THE INVENTION

[0026] The following embodiments describe a system and method for etching a high aspect ratio structure. It will be apparent that these 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 so as not to unnecessarily obscure these embodiments.

[0027] Figure 1 is an embodiment diagram of a high aspect ratio structure 100. Examples of high aspect ratio structures 100 include dynamic random access memory stacks and silicon-oxide-nitride-oxide-silicon (SONOS) stacks. For example, in dynamic random access memory, each data bit is stored in a memory cell that includes a capacitor and a transistor. In this example, 1 bit is stored in the memory cell when the capacitor is charged, and 0 bits are stored in the memory cell when the capacitor is discharged. For example, SONOS stacks are used in non-volatile memories such as flash memory and electrically erasable read-only memory (EEPROM).

[0028] The high aspect ratio structure 100 includes a mask layer, a nitrogen-containing layer 1, an oxide layer 1, another nitrogen-containing layer 2, another oxide layer 2, a nitrogen-containing layer 3, and a substrate layer. For example, the alternating arrangement of nitrogen-containing layers and oxide layers in the high aspect ratio structure forms the dielectric layer of each capacitor in the high aspect ratio structure, and the nitrogen-containing layers and oxide layers are etched to fabricate the capacitor in the high aspect ratio structure. For example, the substrate layer is fabricated from silicon. As shown in the figure, nitrogen-containing layer 3 is superimposed on the substrate layer, and oxide layer 2 is superimposed on nitrogen-containing layer 3. Also, nitrogen-containing layer 2 is deposited on oxide layer 2, and oxide layer 1 is deposited on nitrogen-containing layer 2. Similarly, nitrogen-containing layer 1 is superimposed on oxide layer 1, and the mask layer is deposited on nitrogen-containing layer 1. For example, nitrogen-containing layer 1 is adjacent to oxide layer 1, and oxide layer 1 is adjacent to nitrogen-containing layer 2. Nitrogen-containing layer 2 is adjacent to oxide layer 2, and oxide layer 2 is adjacent to nitrogen-containing layer 3. Nitrogen-containing layer 3 is adjacent to the substrate layer, and the mask layer is adjacent to nitrogen-containing layer 1. For example, two layers of the high aspect ratio structure 100 (e.g., nitrogen-containing layer 1 and oxide layer 1, or oxide layer 1 and nitrogen-containing layer 2) are adjacent to each other when there is no layer between them.

[0029] Examples of nitrogen-containing layers described herein are nitrogen-containing films fabricated from silicon nitride (SiN), silicon carbonitride (SiCN), silicon oxynitride (SiON), or combinations thereof. For example, the nitrogen-containing layer may also be referred to herein as a nitrogen-containing silicon layer or nitride layer. For example, each nitrogen-containing layer in the high aspect ratio structure 100 has a height of 15 nanometers (nm) to 300 nm. For example, nitrogen-containing layer 1 has a thickness of 30 nm, nitrogen-containing layer 2 has a thickness of 50 nm, and nitrogen-containing layer 3 has a thickness of 60 nm. For example, each oxide layer in the high aspect ratio structure 100 has a height of 15 nm to 300 nm. For example, oxide layer 1 has a thickness of 100 nm, and oxide layer 2 has a thickness of 200 nm.

[0030] In one embodiment, a silicon-containing layer, such as a polysilicon (P) layer or a nitrogen-silicon layer, is used instead of the nitrogen-containing layer. For example, each of the nitrogen-containing layers 1, 2, and 3 of the high aspect ratio laminate 100 is replaced by a silicon-containing layer. The silicon-containing layers are etched in the same way as the nitrogen-containing layers 1, 2, and 3. For example, the first silicon-containing layer used in place of nitrogen-containing layer 1 is etched in the same way as nitrogen-containing layer 1, the second silicon-containing layer used in place of nitrogen-containing layer 2 is etched in the same way as nitrogen-containing layer 2, and the third silicon-containing layer used in place of nitrogen-containing layer 3 is etched in the same way as nitrogen-containing layer 3. An example of a nitrogen-silicon layer is a silicon nitride layer.

[0031] Figure 2A is an embodiment diagram of a high aspect ratio structure 200 to illustrate the processing of high aspect ratio structure 100 (Figure 1). High aspect ratio structure 200 contains the same layers as high aspect ratio structure 100 (Figure 1), but in high aspect ratio structure 200, the mask layer and nitrogen-containing layer 1 are etched to form features 202 (such as channels) inside them. The remaining layers of high aspect ratio 100 are not shown in Figure 2A for the sake of clarity.

[0032] Chemical A is applied to etch the mask layer and the nitrogen-containing layer 1. Examples of chemical A include non-metallic gases (such as hydrofluorocarbons or oxygen). Examples of hydrofluorocarbons include difluoromethane (CH2F2), methyl fluoride (CH3F), and trifluoromethane (CHF3). Chemical A is applied to etch the nitrogen-containing layer 1 until a horizontal level 212 reaches the interior of the oxide layer 1. For example, the horizontal level is a level along the x-axis. The horizontal level 212 is at a predetermined depth 204 from the top surface 206 of the oxide layer 1. For example, a recess 201 of a predetermined height is drilled into the interior of the oxide layer 1. The recess 201 is part of a feature 202. The heights described herein are measured along the y-axis. The y-axis is perpendicular to the x-axis, which is aligned horizontally. The y-axis is aligned vertically. Both the x-axis and y-axis are perpendicular to the z-axis.

[0033] The predetermined depth 204 is determined from the top surface 206 of the oxide layer 1. An example of a predetermined depth 204 is a vertical distance of approximately 50 nm. For example, a predetermined depth 204 is 40 nm to 60 nm. Another example is a predetermined depth 204 of 45 nm to 55 nm. Yet another example is a predetermined depth 204 being a fraction of the depth of the oxide layer 1. For example, a predetermined depth 204 is 1 to 10 percent of the depth of the oxide layer 1. The depth of the oxide layer 1 extends from the top surface 206 to the bottom surface 208 of the oxide layer 1. As an example, the depth of the layer used herein extends along the y-axis.

[0034] Within feature 202, the intermediate surface 210 of the oxide layer 1 is exposed when the horizontal level 212 is reached. The intermediate surface 210 forms the bottom surface of feature 202. Upon reaching the horizontal level 212, a recess 201 with a space is formed within the oxide layer 1. For example, the recess 201 is formed between the top surface 206 and the intermediate surface 210 and has a predetermined depth 204. The intermediate surface 210 is located between the top surface 206 and the bottom surface 208. For example, the height of the intermediate surface 210 is less than the height of the top surface 206 but greater than the height of the bottom surface 208. For example, the height of each surface of the high aspect ratio structure 200 is measured from the bottom surface 212 of the substrate layer.

[0035] When chemical A is used to etch nitrogen-containing layer 1, another chemical B is not used to etch nitrogen-containing layer 1. For example, during the period when chemical A is applied to etch nitrogen-containing layer 1, chemical B is not applied to etch nitrogen-containing layer 1. An example of chemical B is a metal-containing compound. For example, a metal-containing compound is a compound that, when applied at a sufficient vapor pressure, provides a gas supply to the high aspect ratio structure 100. An example of a metal-containing compound is a metal-containing gas (such as a carbonyl or metal fluoride). For example, a metal fluoride is tungsten hexafluoride (WF6). In this example, the metal-containing gases applied are fluorocarbons and nitrogen trifluoride (NF3). In this example, a fluorocarbon is a compound formed by substituting one or more hydrogen atoms in a hydrocarbon with one or more fluorine atoms. Other examples of metal-containing compounds include rhenium hexafluoride (ReF6), molybdenum hexafluoride (MoF6), MoCl2F2, tantalum pentafluoride (TaF5), vanadium fluoride (VF5), vanadium oxytrichloride (VOCl3), titanium tetrachloride (TiCl4), plumban (PbH4), tetramethyltin (Sn(CH3)4), nickel tetracarbonyl (Ni(CO)4), and dimethylzinc (Zn(CH3)4). 3)2), these include tungsten(VI) tetrachloride (WOCl4), bis(t-butylimide)bis(dimethylamino)tungsten(VI) (((CH3)3CN)2W(N(CH3)2)2), mesitylenetungsten tricarbonyl (C6H3(CH3)3W(CO)3), tungsten(VI) oxytetrafluoride (WOF4), WO2F2, and tungsten dioxide dichloride (WO2Cl2). An example of a carbonyl is tungsten hexacarbonyl (W(CO)6).

[0036] Note that if chemical substance B is used instead of chemical substance A, an etch stop will occur inside nitrogen-containing layer 1, or nitrogen-containing layer 1 will be under-etched. When nitrogen-containing layer 1 is under-etched, the etching rate of nitrogen-containing layer 1 will be less than the predetermined etching rate.

[0037] Figure 2B is an embodiment diagram of a high aspect ratio structure 220 to show further processing of the high aspect ratio structure 200 (Figure 2A). The high aspect ratio structure 220 contains the same layers as the high aspect ratio structure 100 (Figure 1), but in the high aspect ratio structure 220, the oxide layer 1 is etched in addition to the mask layer and nitrogen-containing layer 1 to form features 222 on the mask layer, nitrogen-containing layer 1, and oxide layer 1. For example, feature 202 (Figure 2A) is further etched to form feature 222. The remaining layers of the high aspect ratio structure 100 are not shown in Figure 2B for clarity.

[0038] After the application of chemical A for etching the nitrogen-containing layer 1 is stopped, chemical B is applied to etching a portion of the oxide layer 1. For example, the application of chemical B begins at horizontal level 212 (Figure 2A). Chemical B is applied until it reaches horizontal level 224. The portion of the oxide layer 1 to be etched is located between horizontal level 212 and horizontal level 224. An example of the amount of the portion of the oxide layer 1 to be etched is 90-95% of the oxide layer 1. Horizontal level 224 is at a predetermined distance 226 from the top surface 228 of the nitrogen-containing layer 2. The top surface 228 of the nitrogen-containing layer 2 is adjacent to or next to the bottom surface 208 of the oxide layer 1. For example, there is no space between the top surface 228 and the bottom surface 208. Note that chemical A is not applied during the period when chemical B is applied to etch the oxide layer 1.

[0039] When the horizontal level reaches 224, the application of chemical substance B is reduced or stopped. If the application of chemical substance B is reduced when the horizontal level reaches 224, the application of chemical substance B is stopped when the horizontal level of the upper surface 228 of the nitrogen-containing layer 2 is reached. Note that chemical substance A is not applied during the period when chemical substance B is applied to etch the oxide layer 1.

[0040] After chemical substance B is stopped or reduced, residual chemical substance B from the application of chemical substance B etches the rest of oxide layer 1 over a predetermined period of time. For example, after chemical substance B is stopped or reduced at horizontal level 224, the oxide of oxide layer 1 is etched by residual chemical substance B until it reaches nitrogen-containing layer 2.

[0041] Chemical substance A is applied after a predetermined period has elapsed since the application of chemical substance B was stopped or reduced. Once chemical substance A is applied, etching of nitrogen-containing layer 2 begins.

[0042] Figure 2C is an embodiment diagram of a high aspect ratio structure 240 to show further processing of the high aspect ratio structure 220 (Figure 2B). The high aspect ratio structure 240 contains the same layers as the high aspect ratio structure 100 (Figure 1), but in the high aspect ratio structure 240, in addition to the mask layer, nitrogen-containing layer 1, and oxide layer 1, nitrogen-containing layer 2 is etched to form features 242 on the mask layer, nitrogen-containing layer 1, oxide layer 1, and nitrogen-containing layer 2. For example, feature 222 (Figure 2B) is further etched to form feature 242. The remaining layers of the high aspect ratio structure 100 are not shown in Figure 2C for the sake of clarity.

[0043] Similar to how chemical substance A is applied to form a recess 201 (Figure 2A) in oxide layer 1, nitrogen-containing layer 2 is etched until a recess 243 is formed in oxide layer 2. For example, chemical substance A is applied to oxide layer 2 until a horizontal level 244 reaches the interior of oxide layer 2. The horizontal level 244 is at a predetermined depth 246 from the top surface 248 of oxide layer 2. For example, a recess of a predetermined height is drilled into the interior of oxide layer 2. The predetermined depth 246 is determined from the top surface 248 of oxide layer 2.

[0044] An example of a predetermined depth 246 is a vertical distance of approximately 50 nm. For example, a predetermined depth 246 is 40 nm to 60 nm. Another example is a predetermined depth 246 of 45 nm to 50 nm. Yet another example is a predetermined depth 246 being a fraction of the depth of oxide layer 2. For example, a predetermined depth 246 is 1 to 10 percent of the depth of oxide layer 2. The depth of oxide layer 2 extends from the top surface 248 to the bottom surface 250 of oxide layer 2.

[0045] For example, a predetermined depth of 246 is equal to a predetermined depth of 204 (Figure 2A). Another example is that a predetermined depth of 246 is not equal to a predetermined depth of 204. For instance, a predetermined depth of 246 is greater than or less than a predetermined depth of 204.

[0046] Within feature 242, the intermediate surface 252 of the oxide layer 2 is exposed when the horizontal level 244 is reached. The intermediate surface 252 is located between the top surface 248 and the bottom surface 250. For example, the height of the intermediate surface 252 is less than the height of the top surface 248 but greater than the height of the bottom surface 250. As previously mentioned, the height of each surface of the high aspect ratio structure 240 is measured from the bottom surface 212.

[0047] When chemical substance A is used to etch nitrogen-containing layer 2, another chemical substance B is not used to etch nitrogen-containing layer 2. For example, during the period when chemical substance A is applied to etch nitrogen-containing layer 2, chemical substance B is not applied to etch nitrogen-containing layer 2. Note that if chemical substance B is used instead of chemical substance A, either an etch stop will occur where nitrogen-containing layer 2 is not etched, or nitrogen-containing layer 2 will be under-etched. When nitrogen-containing layer 2 is under-etched, the etching rate of nitrogen-containing layer 2 will be less than the predetermined etching rate.

[0048] Figure 2D is an embodiment diagram of a high aspect ratio structure 260 showing further processing of the high aspect ratio structure 240 (Figure 2C). The high aspect ratio structure 260 contains the same layers as the high aspect ratio structure 100 (Figure 1), but in the high aspect ratio structure 260, in addition to the mask layer, nitrogen-containing layer 1, oxide layer 1, and nitrogen-containing layer 2, oxide layer 2 is etched to form features 262 on the mask layer, nitrogen-containing layer 1, oxide layer 1, nitrogen-containing layer 2, and oxide layer 2. For example, feature 242 (Figure 2C) is further etched to form feature 262. The remaining layers of the high aspect ratio structure 100 are not shown in Figure 2D for clarity.

[0049] After the application of chemical A for etching nitrogen-containing layer 2 is stopped, chemical B is applied to etching oxide layer 2. For example, the application of chemical B begins at horizontal level 244 (Figure 2C). Chemical B is applied until it reaches horizontal level 264. Horizontal level 264 is close to nitrogen-containing layer 3. For example, horizontal level 264 is at a predetermined distance 266 from the top surface 268 of nitrogen-containing layer 3. As another example, horizontal level 264 is closer to nitrogen-containing layer 3 than to nitrogen-containing layer 2. For example, horizontal level 264 is in the lower half of oxide layer 2 and not in the upper half of oxide layer 2. The top surface 268 of nitrogen-containing layer 3 is adjacent to or next to the bottom surface 250 of oxide layer 2. For example, there is no space between the top surface 268 and the bottom surface 250. Note that chemical A is not applied during the period when chemical B is applied to etching oxide layer 2.

[0050] When the horizontal level reaches 264, the application of chemical substance B is reduced or stopped. If the application of chemical substance B is reduced when the horizontal level reaches 264, the application of chemical substance B is stopped when the horizontal level of the upper surface 268 of the nitrogen-containing layer 2 is reached. Note that chemical substance A is not applied during the period when chemical substance B is applied to etch the oxide layer 2.

[0051] After chemical substance B is stopped or reduced, residual chemical substance B from the application of chemical substance B etches the rest of oxide layer 2 over a predetermined period of time. For example, after chemical substance B is stopped or reduced at horizontal level 264, the oxide of oxide layer 2 is etched by residual chemical substance B until it reaches nitrogen-containing layer 3.

[0052] Chemical substance A is applied and etching of nitrogen-containing layer 3 begins after a predetermined period has elapsed since the application of chemical substance B was stopped or reduced. For example, the predetermined period for etching oxide layer 2 is equal to the predetermined period for etching oxide layer 1. As another example, the predetermined period for etching oxide layer 2 is not equal to the predetermined period for etching oxide layer 1 (for example, longer or shorter than the predetermined period).

[0053] Figure 2E is a diagram of a high aspect ratio structure 280 to show further processing of high aspect ratio structure 260 (Figure 2D). High aspect ratio structure 280 contains the same layers as high aspect ratio structure 100 (Figure 1), but in high aspect ratio structure 280, in addition to the mask layer, nitrogen-containing layer 1, oxide layer 1, nitrogen-containing layer 2, and oxide layer 2, nitrogen-containing layer 3 is etched to form features 282 on the mask layer, nitrogen-containing layer 1, oxide layer 1, nitrogen-containing layer 2, oxide layer 2, and nitrogen-containing layer 3. For example, feature 262 (Figure 2D) is further etched to form feature 282. The remaining layers of high aspect ratio structure 100 are not shown in Figure 2E for the sake of clarity.

[0054] Chemical substance A is applied to etch the nitrogen-containing layer 3 until it reaches the substrate layer. For example, chemical substance A is applied until it reaches the top surface 284 of the substrate layer. The substrate layer extends from the top surface 284 to the bottom surface 212.

[0055] When chemical substance A is used to etch nitrogen-containing layer 3, chemical substance B is not used to etch nitrogen-containing layer 3. For example, during the period when chemical substance A is applied to etch nitrogen-containing layer 3, chemical substance B is not applied to etch nitrogen-containing layer 3. Note that if chemical substance B is used instead of chemical substance A, an etch stop will occur where nitrogen-containing layer 3 is not etched, or nitrogen-containing layer 3 will be under-etched. When nitrogen-containing layer 3 is under-etched, the etching rate of nitrogen-containing layer 3 is less than the predetermined etching rate. In this way, as explained with reference to Figures 2A-2E, chemical substances A and B are applied alternately or consecutively to etch the nitride layer and oxide layer of the high aspect ratio structure 100.

[0056] Figure 3 is a diagram of an embodiment of system 300 showing the application of chemical substances A and B. System 300 comprises a host computer 302, a low-frequency (LF) radio frequency (RF) generator, a high-frequency (HF) RF generator, a matching unit, and a plasma chamber 304. For example, the LFRF generator has an operating frequency of 400 kilohertz (kHz) or 2 megahertz (MHz). For example, the HFRF generator has an operating frequency of 13.56 MHz, 27 MHz, or 60 MHz. Note that the operating frequency of the HFRF generator is higher than that of the LFRF generator. The LFRF generator is an example of a primary generator, and the HFRF generator is an example of a secondary generator.

[0057] A matching circuit is a network of circuit components (such as inductors, capacitors, and resistors). For example, a matching circuit includes one or more shunt circuits and one or more series circuits. Each shunt circuit has one or more circuit components, and so do each series circuit. A first branch circuit, including one or more shunt circuits or one or more series circuits, or a combination thereof, is connected between the input 310 and output 314 of the matching circuit. A second branch circuit, including one or more shunt circuits or one or more series circuits, or a combination thereof, is connected between the input 312 and output 314 of the matching circuit.

[0058] Examples of host computers 302 include desktop computers, laptop computers, controllers, tablets, and smartphones. Host computers 302 comprises a processor 306 and a memory device 308. The processor 306 is connected to the memory device 308. Examples of processors used herein include microprocessors, application-specific integrated circuits (ASICs), programmable logic devices (PLDs), integrated microcontrollers, and central processing units (CPUs). Examples of memory devices used herein include read-only memory (ROM), random-access memory (RAM), flash memory, storage disk arrays, and hard disks.

[0059] The plasma chamber 304 includes a substrate support 316, such as an electrostatic chuck (ESC). The ESC includes a lower electrode 318. The plasma chamber 106 further includes a showerhead 320 into which an upper electrode 322 is embedded. Each of the lower electrode 318 and the upper electrode 322 is made of metal (e.g., aluminum or an aluminum alloy). The bottom surface of the showerhead 320 is located above and opposite the upper surface of the substrate support 316. The substrate S is placed on the upper surface of the substrate 316. An example of the substrate S is a high aspect ratio structure 100 (Figure 1).

[0060] System 300 further comprises a gas source 324 and another gas source 326. Examples of gas sources include containers for storing the chemicals described herein. For example, gas source 324 stores chemical A, and gas source 326 stores chemical B. Another example is gas source 326 storing fluorocarbons and nitrogen trifluoride of chemical B. System 300 further comprises drivers A and B. Examples of drivers include one or more transistors. For example, the drivers include one or more field-effect transistors (FETs) connected to each other.

[0061] The LFRF generator has an output 328 connected to input 310 via RF cable RFC1, which is connected to the first branch circuit of the matching circuit 310. The HFRF generator has an output 330 connected to input 312 via RF cable RFC2, which is connected to the second branch circuit of the matching circuit 310. The first and second branch circuits are connected to each other and to output 314. Output 314 is connected to the lower electrode 318 via RF transmission line RFT. The upper electrode 322 is connected to a reference potential such as ground potential.

[0062] Furthermore, the processor 306 is connected to the LFRF generator via transmission cable TC1 and to the HFRF generator via transmission cable TC2. Examples of transmission cables include cables used for serial data transfer, cables used for parallel data transfer, and Universal Serial Bus (USB) cables.

[0063] Gas source 324 is connected to shower head 320 via gas supply line 332. Gas source 326 is also connected to shower head 320 via gas supply line 334. Examples of gas supply lines include gas ducts and gas pipes. Processor 306 is connected to driver A and also to driver B. Driver A is connected to valve 336, which is connected to gas supply line 332. For example, valve 336 is installed inside gas supply line 332. Similarly, driver B is connected to valve 337, which is connected to gas supply line 334. Examples of valves include valve assemblies. For example, a valve assembly includes a stationary valve plate and a movable valve plate. The movable valve plate slides relative to the stationary valve plate. The stationary valve has multiple openings. Another example of a valve assembly includes a solenoid valve.

[0064] The processor 306 generates a recipe signal containing a recipe and provides it to the LFRF generator via the transmission cable TC1. An example of a recipe provided to the LFRF generator is the frequency level and parameter levels of the LFRF signal 338 (e.g., a sine wave signal) generated by the LFRF generator. Upon receiving the recipe, the LFRF generator stores it.

[0065] Similarly, the processor 306 generates a recipe signal containing a recipe and provides it to the HFRF generator via the transmission cable TC2. An example of a recipe provided to the HFRF generator is the frequency level and parameter levels of the HFRF signal 340 (e.g., a sine wave signal) generated by the HFRF generator. Upon receiving the recipe, the HFRF generator stores it.

[0066] The processor 306 generates a trigger signal (for example, a signal having a single digital pulse) and transmits the trigger signal to the LFRF generator via the transmission cable TC1. The processor 306 also transmits a trigger signal to the HFRF generator via the transmission cable TC2.

[0067] In response to receiving a trigger signal, the LFRF generator generates an RF signal 338 and transmits it to input 310 via output 328 and RF cable RFC1. Also in response to receiving a trigger signal, the HFRF generator generates an RF signal 340 and transmits it to input 312 via output 330 and RF cable RFC2.

[0068] The first branch circuit of the matching circuit 314 receives the RF signal 338 through input 310, and the second branch circuit of the matching circuit 314 receives the RF signal 340 through input 312. The matching circuit 314 modifies the impedances of the RF signals 338 and 340 and outputs the first and second modified RF signals. The impedances of the RF signals 338 and 340 are modified by matching the impedance of the load connected to output 314 with the impedance of the source connected to inputs 310 and 312. Examples of loads include an RF transmission line RFT and a plasma chamber 304. Examples of sources include RF cables RFC1 and RFC2, as well as an LFRF generator and an HFRF generator. The matching circuit 314 further combines (e.g., sums or adds) the first and second modified RF signals and outputs a modified RF signal 342 at output 314. The modified RF signal 342 is provided to the lower electrode 318 through the RF transmission line RFT.

[0069] Furthermore, when the modified RF signal 342 is provided to the plasma chamber 304, chemicals A and B are supplied to the plasma chamber 304 alternately. For example, the processor 306 generates a closing drive signal and transmits it to the driver A. Upon receiving the closing drive signal, the driver A generates a current signal and provides the current signal to the valve 336 to close the valve 336. For example, when the current signal is supplied to the valve 336 to close the valve 336, a field such as an electric field is generated, causing the movable valve plate of the valve 336 to rotate relative to the stationary valve plate of the valve 336, and closing all openings of the stationary valve plate. When the valve 336 is closed, chemical substance A stored in the gas source 324 is not supplied to the showerhead 320 through the gas supply line 332. In this way, when the valve 336 is closed, the application of chemical substance A to the plasma chamber 304 stops.

[0070] As another example, processor 306 generates a fully open drive signal and sends it to driver A. Upon receiving the fully open drive signal, driver A generates a current signal and provides the current signal to valve 336 to fully open valve 336. For example, when a current signal is supplied to valve 336 to fully open valve 336, a field such as an electric field is formed, causing the movable valve plate of valve 336 to rotate relative to the stationary valve plate of valve 336, opening all openings of the stationary valve plate. When valve 336 is fully open, chemical substance A stored in gas source 324 is supplied to shower head 320 through gas supply line 332.

[0071] As yet another example, processor 306 generates a partial-open drive signal and sends it to driver A. Upon receiving the partial-open drive signal, driver A generates a current signal and provides the current signal to valve 336 to partially open valve 336. For example, when a current signal is supplied to valve 336 to partially open valve 336, a field such as an electric field is formed, causing the movable valve plate of valve 336 to rotate relative to the stationary valve plate of valve 336, opening at least one opening of the stationary valve plate, but not all of the openings or part of the openings. When valve 336 is partially open, a small amount of chemical A stored in gas source 324 is supplied to showerhead 320 through gas supply line 332. For example, a small amount of chemical A is supplied when it is substantially less than the amount of chemical A supplied when valve 336 is fully open. To give yet another example, the amount of chemical A is substantially less than the amount of chemical A supplied when valve 336 is fully open, when it is 0.1% to 10% of the amount of chemical A supplied when valve 336 is fully open. In this way, when valve 336 is partially open, the application of chemical substance A is reduced compared to when valve 336 is fully open.

[0072] Similarly, for example, processor 306 generates a close drive signal and sends it to driver B. Upon receiving the close drive signal, driver B generates a current signal and provides the current signal to valve 337 to close valve 337. For example, when a current signal is supplied to valve 337 to close valve 337, a field such as an electric field is formed, causing the movable valve plate of valve 337 to rotate relative to the stationary valve plate of valve 337, and all openings of the stationary valve plate to close. When valve 337 is closed, chemical substance B stored in gas source 326 is not supplied to showerhead 320 through gas supply line 334. In this way, when valve 337 is closed, the application of chemical substance B stops.

[0073] As another example, processor 306 generates a fully open drive signal and sends it to driver B. Upon receiving the fully open drive signal, driver B generates a current signal and provides the current signal to valve 337 to fully open valve 337. For example, when the current signal is supplied to valve 337 to fully open valve 337, a field is formed, causing the movable valve plate of valve 337 to rotate relative to the stationary valve plate of valve 337, opening all openings of the stationary valve plate. Once valve 337 is fully open, chemical B stored in gas source 326 is supplied to showerhead 320 through gas supply line 334.

[0074] As yet another example, processor 306 generates a partial-open drive signal and sends it to driver B. Upon receiving the partial-open drive signal, driver B generates a current signal and provides the current signal to valve 337 to partially open valve 337. For example, when a current signal is supplied to valve 337 to partially open valve 337, a field such as an electric field is formed, causing the movable valve plate of valve 337 to rotate relative to the stationary valve plate of valve 337, opening at least one opening of the stationary valve plate, but not all of the openings or part of the openings. When valve 337 is partially open, a small amount of chemical B stored in gas source 326 is supplied to showerhead 320 through gas supply line 334. For example, a small amount of chemical B is supplied when it is substantially less than the amount of chemical B supplied when valve 337 is fully open. To give another example, the amount of chemical B is substantially less than the amount of chemical B supplied when valve 337 is fully open, when it is between 0.1% and 10% of the amount of chemical B supplied when valve 337 is fully open. In this way, when valve 337 is partially open, the application of chemical substance B is reduced compared to when valve 337 is fully open.

[0075] Chemical substance A or B is alternately supplied through the shower head 320 to the gap 344 between the shower head 320 and the substrate support 316. When the correction signal 342 and chemical substance A or B are supplied to the plasma chamber 304, plasma is generated or maintained in the gap 344 to process (e.g., etch) the substrate S.

[0076] In one embodiment, a table is provided for controlling the application of chemical substances A and B over predetermined periods. This table is stored in a memory device 308 and generated before processing the substrate S. The table includes a list of layers of a high aspect ratio structure 100 (Figure 1) and predetermined periods for etching the layers. For example, the table includes the etching of nitrogen-containing layer 1 in a first period, oxide layer 1 in a second period, nitrogen-containing layer 2 in a third period, oxide layer 2 in a fourth period, and nitrogen-containing layer 3 in a fifth period.

[0077] The processor 306 accesses a table from the memory device 308 and decides to apply chemicals A and B according to the periods in the table. For example, the processor 306 decides to apply chemical A in the first period to etch the nitrogen-containing layer 1 and to apply chemical B in the second period to etch the oxide layer 1. The processor 306 also decides to apply chemical A in the third period to etch the nitrogen-containing layer 2 and to apply chemical B in the fourth period to etch the oxide layer 2. The processor 306 decides to apply chemical A in the fifth period to etch the nitrogen-containing layer 3.

[0078] The processor 306 controls drivers A and B (Figure 3) in corresponding periods of the first to fifth periods in order to etch the nitrogen-containing layer and oxide layer of the high aspect ratio structure 100. For example, the processor 306 controls driver A to fully open valve 336 (Figure 3). Valve 336 is controlled to fully open during the first period. After the first period, the processor 306 controls driver A to close valve 336. Furthermore, in this example, after valve 336 has closed at the end of the first period, the processor 306 controls driver B to fully open valve 337 (Figure 3). Valve 337 is controlled to fully open during the second period. After the second period, the processor 306 controls driver B to close valve 337. In this example, after valve 337 closes at the end of the second period, processor 306 closes valve 336 so that it is fully open in the third period, just as it was controlled to be fully open in the first period. In this example, processor 306 controls valve 336 to close after the third period. Also in this example, after valve 336 closes at the end of the third period, processor 306 controls valve 337 so that it is fully open in the fourth period. In this example, processor 306 controls valve 337 to close after the fourth period. Furthermore in this example, at the end of the fourth period, processor 306 controls valve 336 so that it is fully open in the fifth period. Processor 306 controls valve 336 to close after the fifth period.

[0079] Note that during the first period, nitrogen-containing layer 1 and a portion of oxide layer 1 are etched with chemical A until they reach a horizontal level of 212 (Figure 2A). Similarly, during the second period, oxide layer 1 is etched with chemical B until it reaches a horizontal level of 224 (Figure 2B). Furthermore, during the third period, nitrogen-containing layer 2 and a portion of oxide layer 2 are etched with chemical A until they reach a horizontal level of 244 (Figure 2C). In addition, during the fourth period, oxide layer 2 is etched with chemical B until it reaches a horizontal level of 264 (Figure 2D). Furthermore, during the fifth period, nitrogen-containing layer 3 is etched with chemical A until it reaches the substrate layer.

[0080] In one embodiment, the predetermined duration of the table is pre-calculated according to the thickness of the oxide layer and nitrogen-containing layer of the high aspect ratio structure 100. The duration of the table is pre-calculated during the experimental routine before etching the high aspect ratio structure 100. For example, when nitrogen-containing layer 2 is thicker than nitrogen-containing layer 1, the third duration is longer than the first duration. In another example, when oxide layer 1 is thicker than oxide layer 2, the second duration is longer than the fourth duration. In yet another example, a dummy substrate mimicking the high aspect ratio structure 100 is used to calculate the predetermined duration of the table.

[0081] In this embodiment, the processor 306 determines that the horizontal level 224 is close to the nitrogen-containing layer 2. For example, the horizontal level 224 is closer to the nitrogen-containing layer 2 than to the nitrogen-containing layer 1. For example, the horizontal level 224 is in the lower half of the oxide layer 1 but not in the upper half of the oxide layer 1.

[0082] Figure 4A is an embodiment diagram of system 400 showing the use of an optical sensor 402 to determine the time for switching between the application of chemical substance A and the application of chemical substance B. System 400 has the same components as system 300 (Figure 3), except that it includes an optical sensor 402. Examples of optical sensors 402 include an emission spectrometer (OES), an endpoint detection sensor, or an infrared sensor.

[0083] The optical sensor 402 is positioned relative to the plasma chamber 304 so as to be able to see through the plasma formed in the gap 344. For example, the optical sensor 402 is coupled to a window 404 integrated into the side wall 406 of the plasma chamber 304. The side wall 406 is fixed to the upper wall 408 and the bottom wall 410 of the plasma chamber 304. The side wall 406 is located between wall 408 and wall 410.

[0084] The optical sensor 402 is connected to the processor 306. The processor 306 controls the valve 336 to apply chemical A to the gap 344 in order to etch the nitrogen-containing layer 1. While the nitrogen-containing layer 1 of the substrate S is etched using the modified RF signal 342 and chemical A, the optical sensor 402 senses a first wavelength of plasma formed in the gap 344 and outputs a first electrical signal for a first period. The first electrical signal is transmitted from the optical sensor 402 to the processor 306 for a first period. The processor 306 determines whether the intensity of the first wavelength indicated by the first electrical signal is within a predetermined range, such as the optical intensity range 1 described below. If it is within the predetermined range, the processor 306 determines that the nitrogen-containing layer 1 is still being etched. After the nitrogen-containing layer 1 has been etched and etching of the oxide layer 1 has begun, the optical sensor 402 senses a second wavelength of plasma in the gap 344 and generates a second electrical signal. A second electrical signal is transmitted from the light sensor 402 to the processor 306. The processor 306 determines whether the intensity of the second wavelength indicated by the second electrical signal is outside a predetermined range. For example, the processor 306 determines whether the intensity of the second wavelength is within the light intensity range 2 described below. If it is within the light intensity range 2, the processor 306 controls the valve 336 to close.

[0085] After controlling valve 336 to close, processor 306 controls valve 337 to open. When valve 337 is open, the optical sensor 402 senses a second wavelength of plasma formed in gap 344 and outputs a second electrical signal during a second period. The second period follows the first period. Processor 306 determines whether the second period is equal to a predetermined period. If it determines that the second period is equal to a predetermined period, processor 306 controls valve 337 to close. After controlling valve 377 to close, processor 306 controls valve 336 to open.

[0086] When valve 336 is open, the photosensor 402 senses a first wavelength of plasma formed in gap 344 and outputs a first electrical signal in a third period following a second period. The first electrical signal is transmitted from photosensor 402 to processor 306 in the second period. Processor 306 determines whether the intensity of the first wavelength indicated by the second electrical signal is within a predetermined range. If it is within the predetermined range, processor 306 determines that the nitrogen-containing layer 2 is still being etched. After the nitrogen-containing layer 2 has been etched and the oxide layer 2 has begun to be etched, photosensor 402 senses a second wavelength of plasma in gap 344 and generates a second electrical signal. Processor 306 determines whether the intensity of the second wavelength indicated by the second electrical signal is outside a predetermined range, and if so, controls valve 336 to close.

[0087] After the third period and after controlling valve 336 to close again, processor 306 controls valve 337 to open. When valve 337 opens, photosensor 402 senses the second wavelength of the plasma formed in gap 337 and outputs a second electrical signal in the fourth period. The fourth period is continuous with the third period. Processor 306 determines whether the fourth period is equal to a predetermined period. If it determines that the fourth period is equal to a predetermined period, processor 306 controls valve 337 to close. After controlling valve 337 to close at the end of the fourth period, processor 306 controls valve 336 to open.

[0088] After the fourth period, when the valve 336 opens, chemical A is applied to the gap 344 to etch the nitrogen-containing layer 3. While the nitrogen-containing layer 3 of the substrate S is etched using the modified RF signal 343 and chemical A, the photosensor 402 senses a first wavelength of plasma formed in the gap 344 and outputs a first electrical signal in the fifth period. The fifth period is continuous with the fourth period. The first electrical signal is transmitted from the photosensor 402 to the processor 306 in the fifth period. The processor 306 determines whether the intensity of the first wavelength indicated by the first electrical signal is within a predetermined range. If it is within the predetermined range, the processor 306 determines that the nitrogen-containing layer 3 is still being etched. Having determined that the intensity of the first wavelength indicated by the first electrical signal is within a predetermined range, the processor 306 determines whether the fifth period is equal to a pre-stored period. In response to the determination that the fifth period is equal to a pre-stored period, the processor 306 controls the valve 336 to close in order to stop etching the high aspect ratio structure 280 (Figure 2E).

[0089] In one embodiment, the processor 306 determines that the intensity of the wavelength indicated by the electrical signal output from the optical sensor 402 is inversely proportional to that wavelength. For example, the intensity is low at high wavelengths and high at low wavelengths. As another example, the light intensity decreases as the light wavelength increases and increases as the wavelength decreases.

[0090] In the embodiment, the processor 306 determines the light intensity indicated by the electrical signal based on the amplitude of the electrical signal. For example, it is determined that the intensity is high when the amplitude is high and low when the amplitude is low. As another example, it is determined that the intensity increases as the amplitude increases and decreases as the amplitude decreases.

[0091] In one embodiment, the processor 306 is connected to a clock source and receives a clock signal from the clock source. The processor 306 determines the period described herein by summing the number of clock cycles of the clock signal.

[0092] In one embodiment, instead of determining whether the fifth period is equal to a pre-stored period, the processor 306 determines whether the intensity of the third wavelength indicated by the third electrical signal output from the light sensor 402 is outside a predetermined range. If it determines that the intensity of the third wavelength indicated by the third electrical signal output from the light sensor 402 is outside a predetermined range, the processor 306 controls the valve 336 to close. For example, in response to the determination that the intensity of the third wavelength is within the light intensity range 3, the processor 306 controls the valve 336 to close. For example, light intensity range 3 is different from light intensity ranges 1 and 2. To give another example, light intensity range 3 does not include light intensity ranges 1 and 2.

[0093] In embodiments, the terms predetermined, specified, and pre-stored are used synonymously in this specification.

[0094] Figure 4B is an embodiment diagram of system 450 showing the use of light intensity ranges for etching different layers of a high aspect ratio structure 100 (Figure 1). System 450 comprises a processor 306 and a memory device 308. The memory device 308 stores a list 452 of light intensity ranges and corresponding layers. For example, list 452 includes a correspondence (e.g., mapping) between light intensity range 1 and nitrogen-containing layers 1, 2, or 3 of the high aspect ratio structure 100. List 452 further includes a correspondence between light intensity range 2 and oxide layers 1 or 2 of the high aspect ratio structure 100.

[0095] Note that one or more values ​​in light intensity range 1 are different from (for example, not equal to) one or more values ​​in light intensity range 2. For example, values ​​in light intensity range 1 do not include values ​​in light intensity range 2.

[0096] The processor 306 determines whether the light intensity indicated by the electrical signal received from the light sensor 402 (Figure 4A) is within the light intensity range 1. If it determines that it is within the light intensity range 1, the processor 306 determines that the nitrogen-containing layer 1, 2, or 3 has been etched.

[0097] The processor 306 further determines whether the light intensity indicated by the electrical signal obtained from the light sensor 402 is within the light intensity range 2. In response to the determination that it is within the light intensity range 2, the processor 306 determines that the oxide layer 1 or 2 has been etched.

[0098] In one embodiment, List 452 includes a correspondence between the light intensity range 3 and the substrate layer. The processor 306 determines whether the light intensity indicated by the electrical signal received from the light sensor 402 is within the light intensity range 3. If it determines that it is within the light intensity range 3, the processor 306 determines that the substrate layer is etched.

[0099] Figure 5A is an embodiment of graph 500 showing pulse versus time t for RF signal 338 (Figure 3). Graph 500 plots parameter levels versus time t for RF signal 338. Examples of parameters include voltage and power. An example of a parameter level is the peak-to-peak amplitude. Another example of a parameter level is the zero-peak amplitude. The parameter levels of RF signal 338 are plotted on the y-axis, and time t is plotted on the x-axis.

[0100] The y-axis plots parameter levels PR0, PR1, PR3, PR5, PR7, PR9, PR11, and PR13, while the x-axis plots time t0, t1, t2, t3, etc., up to time ta and t(a+1) (where a is an integer greater than 3). The x-axis further plots time t(a+2), time t(a+3), etc., up to time t(a+b) (where b is an integer greater than 3).

[0101] Parameter level PR3 is greater than parameter level PR1, and parameter level PR1 is greater than parameter level PR0. Similarly, parameter level PR5 is greater than parameter level PR3, and parameter level PR7 is greater than parameter level PR5. Also, parameter level PR9 is greater than parameter level PR7, and parameter level PR11 is greater than parameter level PR9. Parameter level PR13 is greater than parameter level PR11.

[0102] Similarly, the y-axis also has parameter levels PR2, PR4, PR6, PR8, PR10, and PR12. Parameter level PR2 lies between parameter levels PR1 and PR3 (for example, in the middle). Similarly, parameter level PR4 lies between parameter levels PR3 and PR5, and parameter level PR6 lies between parameter levels PR5 and PR7. Also, parameter level PR8 lies between parameter levels PR7 and PR9, parameter level PR10 lies between parameter levels PR9 and PR11, and parameter level PR12 lies between parameter levels PR11 and PR13.

[0103] During the period when chemical substance A is applied to the substrate S through the showerhead 322 (Figure 3), the RF signal 338 has parameter levels PR3 and PR1, and periodically transitions between parameter levels PR3 and PR1. For example, the RF signal 338 is at parameter level PR3 in the time interval between time t0 and time t1. The RF signal 338 transitions from parameter level PR3 to parameter level PR1 at time t1 and remains at parameter level PR1 in the time interval between time t1 and time t2. The RF signal 338 transitions from parameter level PR1 to parameter level PR3 at time t2 and remains at parameter level PR3 in the time interval between time t2 and time t3. The RF signal 338 transitions from parameter level PR3 to parameter level PR1 at time t3. Therefore, the RF signal 338 transitions between parameter levels PR1 and PR3 while chemical substance A is being applied. Chemical substance A is applied from time t0 to time ta.

[0104] As another example, processor 306 (Figure 3) decides to control valve 336 to apply chemical substance A to substrate S at time t0. Also at time t0, processor 306 sends a first command signal to LFRF generator (Figure 3) to transition RF signal 338 from parameter level PR11 or PR13 to parameter level PR3, and periodically transitions RF signal 338 between parameter levels PR3 and PR1. In response to receiving the first command signal at time t0, LFRF generator corrects the parameter level PR11 or PR13 of RF signal 338 to parameter level PR3, and transitions RF signal 338 between parameter levels PR3 and PR1 during the time interval between time t0 and time ta.

[0105] Furthermore, during the period when chemical substance B is applied to the substrate S, the RF signal 338 has parameter levels PR13 and PR11, and periodically transitions between parameter levels PR13 and PR11. For example, the RF signal 338 is at parameter level PR13 in the time interval between time ta and time t(a+1). The RF signal 338 transitions from parameter level PR13 to parameter level PR11 at time t(a+1), and remains at parameter level PR11 in the time interval between time t(a+1) and time t(a+2). The RF signal 338 transitions from parameter level PR11 to parameter level PR13 at time t(a+2), and remains at parameter level PR13 in the time interval between time t(a+2) and time t(a+3). The RF signal 338 transitions from parameter level PR13 to parameter level PR11 at time t(a+3). Therefore, the RF signal 338 transitions between parameter levels PR11 and PR13 while chemical substance B is being applied. Chemical substance B is applied from time ta to time t(a+b).

[0106] As another example, processor 306 (Figure 3) decides to control valve 337 to apply chemical substance B to substrate S at time ta. Also at time ta, processor 306 sends a second command signal to LFRF generator (Figure 3) to transition RF signal 338 from parameter level PR1 to parameter level PR13, and periodically transitions RF signal 338 between parameter levels PR13 and PR11. In response to receiving the second command signal at time ta, LFRF generator corrects parameter level PR1 or PR3 of RF signal 338 to parameter level PR13, and transitions RF signal 338 between parameter levels PR13 and PR11 during the time interval between time ta and time t(a+b). Thus, as described with reference to Figure 5A, RF signal 338 is controlled by processor 306 via LFRF generator to alternate between sets of parameter levels PR3 and PR1 or sets of parameter levels PR13 and PR11, depending on whether chemical substance A or B is applied.

[0107] Note that during the application of chemical substance A, parameter level PR3 corresponds to state S1 of RF signal 338, and parameter level PR1 corresponds to state S0 of RF signal 338. Similarly, parameter level PR13 defines state S1 of RF signal 338 during the application of chemical substance B, and parameter level PR11 defines state S0 of RF signal 338 during the application of chemical substance B.

[0108] In one embodiment, the RF signal 338 transitions between parameter levels PR0 and PR2 instead of between parameter levels PR1 and PR3.

[0109] Figure 5B is an embodiment of graph 550 showing the pulse versus time t of the RF signal 340 (Figure 3). Graph 550 plots the parameter levels versus time t of the RF signal 340. The parameter levels of the RF signal 340 are plotted on the y-axis, and time t is plotted on the x-axis. The y-axis of graph 550 plots the parameter levels PR0 to PR4. The x-axis of graph 550 plots the times t0, t1, t2, t3, etc., up to time t(a+b).

[0110] During the period when chemical substance A is applied to substrate S, the RF signal 340 has parameter levels PR3 and PR1, and periodically transitions between parameter levels PR3 and PR1, similar to how RF signal 338 transitions between parameter levels PR3 and PR1. For example, at time t0, processor 306 (Figure 3) decides to open valve 336 to apply chemical substance A to substrate S. Also at time t0, processor 306 sends a first command signal to HFRF generator (Figure 3) to transition RF signal 340 from parameter level PR4 or PR2 to parameter level PR3, and periodically transitions RF signal 340 between parameter levels PR3 and PR1. In response to receiving the first command signal at time t0, HFRF generator corrects the parameter level PR4 or PR2 of RF signal 340 to parameter level PR3, and transitions RF signal 340 between parameter levels PR3 and PR1 during the time interval between time t0 and ta.

[0111] As another example, the ratio of the parameter level of RF signal 338 to the parameter level of RF signal 340 during the period t0 to ta is between 0.75 and 1.25. For example, during the period t0 to ta, the parameter level of RF signal 338 is 75% or 80% of the parameter level of RF signal 340. As yet another example, during the period t0 to ta, the parameter level of RF signal 338 is equal to the parameter level of RF signal 340. As yet another example, during the period t0 to ta, the parameter level of RF signal 338 is 120% of the parameter level of RF signal 340.

[0112] As yet another example, the ratio of the parameter level of RF signal 338 to the parameter level of RF signal 340 during the period between time ta and t(a+b) is between 2 and 4. For example, the parameter level of RF signal 338 during the period between time ta and t(a+b) is twice the parameter level of RF signal 340. As yet another example, the parameter level of RF signal 338 during the period between time ta and t(a+b) is equal to three times the parameter level of RF signal 340.

[0113] Furthermore, during the period when chemical substance B is applied to the substrate S, the RF signal 340 has parameter levels PR4 and PR2, and periodically transitions between parameter levels PR4 and PR2. For example, the RF signal 340 is at parameter level PR4 in the time interval between time ta and t(a+1). The RF signal 340 transitions from parameter level PR4 to parameter level PR2 at time t(a+1), and remains at parameter level PR2 in the time interval between time t(a+1) and time t(a+2). The RF signal 340 transitions from parameter level PR2 to parameter level PR4 at time t(a+2), and remains at parameter level PR4 in the time interval between time t(a+2) and t(a+3). The RF signal 340 transitions from parameter level PR4 to parameter level PR2 at time t(a+3). Therefore, the RF signal 340 transitions between parameter levels PR4 and PR2 while chemical substance B is applied.

[0114] As another example, processor 306 sends a command signal to the HFRF generator at time ta to transition RF signal 340 from parameter level PR1 to parameter level PR4, and then periodically transitions RF signal 340 between parameter levels PR4 and PR2. In response to receiving the second command signal at time ta, the HFRF generator corrects parameter level PR1 or PR3 of RF signal 338 to parameter level PR4, and transitions RF signal 340 between parameter levels PR4 and PR1 during the time interval between time ta and t(a+b). In this way, as illustrated with reference to Figure 5B, RF signal 340 is controlled by processor 306 via the HFRF generator to alternate between sets of parameter levels PR3 and PR1 or sets of parameter levels PR4 and PR2, based on whether chemical substance A or B is applied to the plasma chamber 304.

[0115] Note that the parameter levels of an RF signal contain one or more values ​​of the RF signal's parameters. For example, a first parameter level does not contain any other parameter values. For example, all values ​​of a first parameter level do not contain any values ​​of a second parameter level (e.g., they are not equal to them).

[0116] It should be further noted that during the application of chemical substance A, parameter level PR3 corresponds to state S1 of RF signal 340, and parameter level PR1 corresponds to state S0 of RF signal 340. Similarly, parameter level PR4 defines state S1 of RF signal 340 during the application of chemical substance B, and parameter level PR2 defines state S0 of RF signal 340 during the application of chemical substance B.

[0117] Figure 6 is an embodiment diagram of system 600 showing an LFRF generator and an HFRF generator for achieving pulsed levels during the application of chemicals A and B. System 600 comprises a processor 306, a memory device 308, an LFRF generator, and an HFRF generator.

[0118] The LFRF generator includes a digital signal processor DSPLF, a parameter controller PRSLF1, another parameter controller PRSLF0, and an automatic frequency tuner AFTLF. The LFRF generator further includes a driver DRVRLF and a power supply PLF. Examples of controllers used herein include ASICs, PLDs, and microprocessors connected to memory devices. Examples of tuners used herein include controllers. For example, a tuner includes a microprocessor, ASIC, or PLD. Examples of power supplies used herein include an electronic oscillator or RF oscillator that generates a periodically oscillating electronic signal, such as a sinusoidal RF signal.

[0119] The digital signal processor DSPLF is connected to the parameter controllers PRSLF1 and PRSLF0, as well as the automatic frequency tuner AFTLF. Each of the parameter controllers PRSLF1 and PRSLF0, and the automatic frequency tuner AFTLF, is connected to the driver DRVRLF, which is connected to the power supply PLF. The power supply PLF is connected to the RF cable RFC1.

[0120] Similarly, the HFRF generator includes a digital signal processor DSPHF, a parameter controller PRSHF1, another parameter controller PRSHF0, and an automatic frequency tuner AFTHF. The HFRF generator further includes a driver DRVRHF and a power supply PHF.

[0121] The digital signal processor DSPHF is connected to the parameter controllers PRSHF1 and PRSHF0, and the automatic frequency tuner AFTHF. Each of the parameter controllers PRSHF1 and PRSHF0, and the automatic frequency tuner AFTHF, is connected to the driver DRVRHF, which is connected to the power supply PHF. The power supply PHF is connected to the RF cable RFC2.

[0122] Processor 306 is connected to the digital signal processor DSPLF via transmission cable TC1. Processor 306 is also connected to the digital signal processor DSPHF via transmission cable TC2.

[0123] The processor 306 transmits a recipe signal 602 to the digital signal processor DSPLF via the transmission cable TC1. The recipe signal 602 includes the parameter levels of state S1 of the RF signal 338 to be realized during the application of chemical substance A, the parameter levels of state S0 of the RF signal 338 to be realized during the application of chemical substance A, the parameter levels of state S1 of the RF signal 338 to be realized during the application of chemical substance B, and the parameter levels of state S0 of the RF signal 338 to be realized during the application of chemical substance B. The recipe signal 602 also includes the frequencies of the RF signals 338 to be realized during the application of chemical substances A and B. The recipe signal 602 further includes the duty cycle of state S1 when chemical substance A is applied, and the duty cycle of state S1 when chemical substance B is applied.

[0124] Upon receiving recipe signal 602, the digital signal processor DSPLF transmits the parameter level and duty cycle of state S1 of RF signal 338 to be realized during the application of chemicals A and B to parameter controller PRSLF1. Similarly, in response to the reception of recipe signal 602, the digital signal processor DSPLF transmits the duty cycle of state S1 of RF signal 338 and the parameter level of state S0 of signal 338 to be realized during the application of chemicals A and B to parameter controller PRSLF0. The digital signal processor DSPLF also transmits the frequency of RF signal 338 to be realized during the application of chemicals A and B to the automatic frequency tuner AFTLF.

[0125] Parameter controller PRSLF1 stores the parameter level and duty cycle of state S1 of RF signal 338 to be realized during the application of chemicals A and B in its memory device. Similarly, parameter controller PRSLF0 stores the duty cycle of state S1 of RF signal 338 and the parameter level of state S0 of RF signal 338 to be realized during the application of chemicals A and B in its memory device. In addition, automatic frequency tuner AFTLF stores the frequency of RF signal 338 to be realized during the application of chemicals A and B in its memory device.

[0126] During or concurrently with the application of chemical substance L (e.g., chemical substance A or B), the processor 306 generates corresponding instruction signals (e.g., a first or second instruction signal) and transmits them to the digital signal processor DSPLF via the transmission cable TC1. For example, the first instruction signal corresponds to chemical substance A (e.g., has a one-to-one relationship or mapping), and the second instruction signal corresponds to chemical substance B.

[0127] Upon receiving a corresponding command signal from processor 306, the digital signal processor DSPLF transmits the corresponding command signal generated during the application of chemical L to parameter controllers PRSLF1 and PRSLF0 and automatic frequency tuner AFTLF. In response to receiving the corresponding command signal during the application of chemical L, parameter controller PRSLF1 generates a command signal based on the parameter level of state S1 of RF signal 338 and transmits the command signal to driver DRVRLF. The command signal is transmitted to driver DRVRLF to generate a drive signal (e.g., a current signal) for the duty cycle period of state S1 during the application of chemical L. In addition, upon receiving a corresponding command signal during the application of chemical L, automatic frequency tuner AFTLF generates a command signal based on the frequency of RF signal 338 to be generated and transmits the command signal to driver DRVRLF. Upon receiving command signals from parameter controller PRSLF1 and automatic frequency tuner AFTLF, driver DRVRLF generates a drive signal for the duty cycle period of state S1 of RF signal 338 during the application of chemical L. The power supply PLF receives a drive signal from the driver DRVRLF during the period of state S1, generates state S1 of the RF signal 338 during the application period of the chemical substance L, and transmits the RF signal 338 having state S1 to the matching unit through output 338 and RF cable RFC1.

[0128] Furthermore, upon receiving a corresponding command signal during the application of chemical substance L, the parameter controller PRSLF0 waits for the duration of the duty cycle of RF signal 338 state S1 before generating a command signal based on the parameter level of RF signal 338 state S0. After waiting, the parameter controller PRSLF0 generates a command signal and transmits it to the driver DRVRLF. The command signal is transmitted to the driver DRVRLF to generate a drive signal for the duration of the duty cycle of state S0 during the application of chemical substance L. For example, the duty cycle of RF signal 338 state S0 is the difference between the duty cycle of RF signal 338 at 100% and the duty cycle of state S1. Upon receiving command signals from the parameter controller PRSLF0 and the automatic frequency tuner AFTLF, the driver DRVRLF generates a drive signal for the duration of the duty cycle of RF signal 338 state S0 during the application of chemical substance L. The power supply PLF receives a drive signal of state S0 from the driver DRVRLF, generates an RF signal 338 of state S0 for the duration of state S0 during the application of chemical L, and transmits the RF signal 338 with state S0 to the matcher through output 328 and RF cable RFC1.

[0129] Note that the drive signal for state S0 of RF signal 338 during the application of chemical substance L is generated and transmitted during the remainder of the clock cycle of the clock signal. For example, the duty cycle of state S1 of RF signal 338 during the application of chemical substance L is 50% of the clock cycle, and the remainder is the remaining 50% of the clock cycle. The clock signal is generated by processor 306 and supplied by processor 306 to digital signal processor DSPLF via transmission cable TC1. Digital signal processor DSPLF transmits the clock signal to parameter controllers PRSLF1 and PRSLF2. After the drive signal for state S0 during the application of chemical substance L has been generated and transmitted during the remainder of the clock cycle, parameter controller PRSLF1 again generates a command signal based on the parameter level of state S1 of RF signal 338 and transmits the command signal to driver DRVRLF. In this way, states S1 and S0 of RF signal 338 alternate periodically during the application of chemical substance L.

[0130] Similarly, for the HFRF generator, processor 306 transmits a recipe signal 604 to the digital signal processor DSPHF via transmission cable TC2. The recipe signal 604 includes the parameter levels of state S1 of the RF signal 340 to be realized during the application of chemical substance A, the parameter levels of state S0 of the RF signal 340 to be realized during the application of chemical substance A, the parameter levels of state S1 of the RF signal 340 to be realized during the application of chemical substance B, and the parameter levels of state S0 of the RF signal 340 to be realized during the application of chemical substance B. The recipe signal 604 also includes the frequencies of the RF signals 340 to be realized during the application of chemical substances A and B. The recipe signal 604 further includes the duty cycle for state S1 of the RF signal 340 during the application of chemical substance A, and the duty cycle for state S1 of the RF signal 340 during the application of chemical substance B.

[0131] Upon receiving recipe signal 604, the digital signal processor DSPHF transmits the parameter level and duty cycle of state S1 of RF signal 340 to be realized during the application of chemicals A and B to parameter controller PRSHF1. Similarly, in response to receiving recipe signal 604, the digital signal processor DSPHF transmits the duty cycle of state S1 of RF signal 340 and the parameter level of state S0 of RF signal 340 to be realized during the application of chemicals A and B to parameter controller PRSHF0. The digital signal processor DSPHF also transmits the frequency of RF signal 340 to be realized during the application of chemicals A and B to automatic frequency tuner AFTHF.

[0132] Parameter controller PRSHF1 stores the duty cycle and parameter level of state S1 of RF signal 340 to be realized during the application of chemicals A and B in its memory device. Similarly, parameter controller PRSHF0 stores the duty cycle of state S1 of RF signal 340 and the parameter level of state S0 of RF signal 340 to be realized during the application of chemicals A and B in its memory device. Automatic frequency tuner AFTHF also stores the frequency of RF signal 340 to be realized during the application of chemicals A and B in its memory device.

[0133] During the application of chemical substance L, processor 306 generates a corresponding command signal and transmits it to digital signal processor DSPHF via transmission cable TC2. Upon receiving the corresponding command signal, digital signal processor DSPHF transmits the corresponding command signal generated during the application of chemical substance L to parameter controllers PRSHF1 and PRSHF0 and automatic frequency tuner AFTHF. In response to receiving the corresponding command signal during the application of chemical substance L, parameter controller PRSHF1 generates a command signal based on the parameter level of state S1 of RF signal 340 and transmits the command signal to driver DRVRHF. The command signal is transmitted to driver DRVRHF to generate a drive signal (e.g., a current signal) for the duty cycle period of state S1 during the application of chemical substance L. In addition, upon receiving the corresponding command signal during the application of chemical substance L, automatic frequency tuner AFTHF generates a command signal based on the frequency of RF signal 340 and transmits the command signal to driver DRVRHF. Upon receiving command signals from parameter controller PRSHF1 and automatic frequency tuner AFTHF, driver DRVRHF generates a drive signal for the period of state S1 of RF signal 340 during the application of chemical substance L. The power supply PHF receives a drive signal of state S1 from the driver DRVRHF, generates state S1 of RF signal 340 for the duration of state S1 of RF signal 340 during the application of chemical substance L, and transmits RF signal 340 having state S1 to the matcher through output 330 and RF cable RFC2.

[0134] Furthermore, upon receiving a corresponding command signal during the application of chemical substance L, the parameter controller PRSHF0 waits for the duration of the duty cycle of state S1 of RF signal 340 before generating a command signal based on the parameter level of state S0 of RF signal 340. After waiting, the parameter controller PRSHF0 generates a command signal and transmits it to the driver DRVRHF. The command signal is transmitted to the driver DRVRHF to generate a drive signal for the duration of the duty cycle of state S0 during the application of chemical substance L. Upon receiving command signals from the parameter controller PRSHF0 and the automatic frequency tuner AFTHF, the driver DRVRHF generates a drive signal for the duration of state S0 of RF signal 340 during the application of chemical substance L. The duration of state S0 of RF signal 340 is the difference between 100% of RF signal 340 and the duty cycle of state S1. The power supply PHF receives a drive signal of state S0 from the driver DRVRHF, generates a state S0 for RF signal 340 for the duration of state S0 during the application of chemical L, and transmits RF signal 340 having state S0 to the matcher through output 330 and RF cable RFC2.

[0135] Note that the drive signal for state S0 of the RF signal 340 while chemical substance L is applied is generated and transmitted during the remainder of the clock cycle of the clock signal. For example, the duty cycle for state S1 of the RF signal 340 while chemical substance L is applied is 50% of the clock cycle, and the remaining period is the remaining 50% of the clock cycle. The clock signal is supplied by processor 306 to the digital signal processor DSPHF via transmission cable TC2. The digital signal processor DSPHF transmits the clock signal to parameter controllers PRSHF1 and PRSHF2.

[0136] After the drive signal for state S0 during the application of chemical substance L is generated and transmitted for the remainder of the clock cycle, the parameter controller PRSHF1 generates a command signal again based on the parameter level of state S1 of RF signal 340 and transmits the command signal to driver DRVRHF. In this way, states S1 and S0 of RF signal 340 alternate periodically during the application of chemical substance L.

[0137] In one embodiment, the digital signal processor DSPLF, and one or more of the controllers PRSLF1, PRSLF0, and AFTLF are integrated within any number of controllers. For example, the functions described herein as being performed by the digital signal processor DSPLF, and one or more of the controllers PRSLF1, PRSLF0, and AFTLF are performed by a single controller. As another example, the functions described herein as being performed by the digital signal processor DSPLF, and one or more of the controllers PRSLF1, PRSLF0, and AFTLF are performed by two or more controllers.

[0138] Similarly, in one embodiment, the digital signal processor DSPHF, and one or more of the controllers PRSHF1, PRSHF0, and AFTHF are integrated within any number of controllers. For example, the functions described herein as being performed by the digital signal processor DSPHF, and one or more of the controllers PRSHF1, PRSHF0, and AFTHF are performed by a single controller. As another example, the functions described herein as being performed by the digital signal processor DSPHF, and one or more of the controllers PRSHF1, PRSHF0, and AFTHF are performed by two or more controllers.

[0139] In this embodiment, each chemical substance A or B is removed from the plasma chamber 304 (Figure 3) after the application of one chemical substance A or B but before the application of another chemical substance B or A. For example, chemical substance A is removed before the application of chemical substance B, and chemical substance B is removed before the application of chemical substance A. For example, one or more vacuum pumps are connected to the plasma chamber 304. A processor 306 is connected to one or more vacuum pumps via one or more corresponding drivers. After a chemical substance L (e.g., chemical substance A or B) is applied to the gap 344 (Figure 3) and a predetermined period has elapsed since the application of chemical substance L, the processor 306 sends one or more turn-on command signals to one or more drivers. Upon receiving one or more turn-on command signals, one or more corresponding drivers generate one or more current signals and send one or more corresponding current signals to one or more corresponding vacuum pumps to turn on one or more vacuum pumps. Once one or more vacuum pumps are turned on, one or more vacuum pumps remove chemical substance L from the plasma chamber 304.

[0140] In this embodiment, the processor 306 determines whether a preset time has elapsed since one or more vacuum pumps were turned on. If it determines that the preset time has elapsed, the processor 306 decides to turn off one or more vacuum pumps. To turn off one or more vacuum pumps, the processor 306 sends one or more turn-off command signals to one or more drivers. Upon receiving one or more turn-off command signals, the corresponding one or more drivers generate corresponding current signals and send corresponding current signals to the corresponding one or more vacuum pumps to turn off one or more vacuum pumps. When one or more vacuum pumps are turned off, they do not remove chemical L from the plasma chamber 304. Also, during the period when one or more vacuum pumps are turned off, chemical L (e.g., B or A) is applied to the gap 344 of the plasma chamber 304. In this way, chemicals A and B are applied alternately and removed from the plasma chamber 304.

[0141] The embodiments described herein may be implemented by various computer system configurations, including handheld hardware units, microprocessor systems, microprocessor-based home appliances or programmable home appliances, minicomputers, and mainframe computers. The embodiments described herein can also be implemented in a distributed computing environment in which tasks are performed by remote processing hardware units connected via a computer network.

[0142] In some embodiments, the controller is part of a system which may be part of the examples described above. This system includes a semiconductor processing apparatus comprising a processing tool, a chamber, a processing platform, and / or specific processing components (such as a wafer pedestal, a gas flow system, etc.). This system is integrated with electronic equipment for controlling pre-processing, processing, and post-processing operations of semiconductor wafers or substrates. These electronic components may be referred to as “controllers” and may control various components or sub-components of the system. Depending on the processing requirements and / or the type of system, the controller is programmed to control any of the processes disclosed herein, including the supply of processing 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 supply settings, position operation settings, wafer loading and unloading to and from tools and other transport tools, and / or wafer loading and unloading to and from load locks connected to or coupled to a particular system.

[0143] In general, in various embodiments, a controller is defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive and issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. An integrated circuit includes a firmware-type chip that stores program instructions, a chip defined as a DSP, an ASIC, and one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions are instructions that are communicated to the controller in the form of various individual settings (or program files) that define operating parameters for performing a process on or for a semiconductor wafer. In some embodiments, the operating parameters are part of a recipe defined by a process engineer to realize one or more processing steps in the manufacturing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer molds.

[0144] In some embodiments, the controller is part of a computer that is integrated with or connected to the system, or otherwise networked to the system, or a combination of both, or connected to such a computer. For example, the controller resides in a “cloud” that enables remote access to wafer processing, or is all or part of a fab host computer system. The controller enables remote access to the system to monitor the progress of manufacturing operations, review the history of past manufacturing operations, examine trends or performance benchmarks from multiple manufacturing operations, modify parameters of the current process, set up subsequent processing steps for the current process, or start a new process.

[0145] In some examples, a remote computer (e.g., a server) provides a process recipe to the system via a computer network, including a local network or the Internet. The remote computer includes a user interface that enables the entry or programming of parameters and / or settings to be transmitted from the remote computer to the system. In some examples, a controller receives instructions for processing a wafer in configuration form. It should be understood that this configuration is specific to the type of process performed on the wafer and the type of tools the controller connects to or controls. Thus, as described above, the controller is distributed by including, for example, one or more separate controllers networked together and cooperating toward the common purpose of performing, for example, the processes described herein. An example of controllers distributed for such a purpose includes one or more integrated circuits in a chamber that are located remotely (e.g., at the platform level or as part of a remote computer) and communicate with one or more integrated circuits that cooperate to control the process in the chamber.

[0146] Without limiting them, in various embodiments, the plasma systems described herein include plasma etching chambers, deposition chambers, spin rinse chambers, metal plating chambers, cleaning chambers, bevel edge etching chambers, physical vapor deposition (PVD) chambers, chemical vapor deposition (CVD) chambers, atomic layer deposition (ALD) chambers, atomic layer etching (ALE) chambers, ion implantation chambers, track chambers, or any other semiconductor processing chambers associated with or used in the fabrication and / or manufacture of semiconductor wafers.

[0147] Although the above operation has been described with reference to a parallel-plate plasma chamber (e.g., a capacitively coupled plasma chamber), in some embodiments the above operation can be applied to other types of plasma chambers (e.g., plasma chambers including inductively coupled plasma (ICP) reactors, trans-coupled plasma (TCP) reactors, conductor tools, dielectric tools, and electron cyclotron resonance (ECR) reactors). For example, X MHz RF generators, Y MHz RF generators, and Z MHz RF generators are connected to inductors in an ICP plasma chamber.

[0148] As described above, depending on the processing steps performed by the tool, the controller communicates with one or more of the following: other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools installed throughout the factory, the main computer, another controller, or tools used for material handling to load and unload wafer containers to and from tool locations and / or load ports in a semiconductor manufacturing plant.

[0149] With the above embodiments in mind, it should be understood that some embodiments utilize various computer operations on data stored in a computer system. Computer operations are operations that manipulate physical quantities.

[0150] Some embodiments also relate to hardware units or devices for performing these operations. These devices are specifically configured for dedicated computers. Defined as dedicated computers, a computer can operate for a specific purpose while still performing other processes, program executions, or routines that are not part of that specific purpose.

[0151] In some embodiments, the operations described herein are performed by a selectively invoked computer, or are set up by one or more computer programs stored in computer memory, or are obtained through a computer network. When data is obtained through a computer network, the data may be processed by other computers on the computer network (e.g., a cloud of computing resources).

[0152] One or more embodiments described herein can also be created as computer-readable code on non-temporary computer-readable media. Non-temporary computer-readable media is any data storage hardware unit (e.g., a memory device) that stores data to be read later by a computer system. Examples of non-temporary computer-readable media include hard drives, network-attached storage (NAS), ROM, RAM, compact disk ROM (CD-ROM), readable CD (CD-R), rewritable CD (CD-RW), magnetic tape, and other optical and non-optical data storage hardware units. In some embodiments, the non-temporary computer-readable media includes computer-readable tangible media distributed through a networked computer system so that the computer-readable code is stored and executed in a distributed manner.

[0153] While some of the method operations described above are shown in a specific order, in various embodiments, other housekeeping operations may be performed between method operations, or the method operations may be timed to occur at slightly different intervals, or they may be distributed in a system that allows method operations to occur at various intervals, or they may be performed in a different order than described above.

[0154] It should be further noted that in the embodiments described above, one or more features of any embodiment may be combined with one or more features of any other embodiments without departing from the scope described in the various embodiments described herein.

[0155] While the embodiments described above have been explained in some detail for clear understanding, it will be apparent that certain changes and modifications are possible within the scope of the appended claims. Therefore, these embodiments should be considered illustrative rather than restrictive, and the embodiments should not be limited to the details described herein, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. A method for etching a layer, A step of etching the first nitrogen-containing layer of the laminate by applying a non-metallic gas, When it is determined that the first oxide layer below the first nitrogen-containing layer has been reached, the application of the nonmetallic gas is stopped. A step of etching the first oxide layer by applying a metal-containing gas, When it is determined that the second nitrogen-containing layer below the first oxide layer has been reached, the application of the metal-containing gas is stopped. A step of etching the second nitrogen-containing layer by applying the nonmetallic gas, Methods that include...

2. The method according to claim 1, A method wherein the first oxide layer is reached when the first oxide layer is being etched, and is etched when it reaches a predetermined depth from the upper surface of the oxide layer.

3. The method according to claim 1, A method comprising etching the first nitrogen-containing layer until a recess is formed in the first oxide layer, wherein the application of the nonmetallic gas is stopped when it is determined that the recess has been formed in the first oxide layer.

4. The method according to claim 3, A method wherein the recess has a predetermined depth.

5. The method according to claim 1, further, For the step of etching the first nitrogen-containing layer, the step of supplying a low-frequency radio frequency (LFRF) signal having a first primary parameter level and a second primary parameter level, The process involves modifying the first primary parameter level to a third primary parameter level and modifying the second primary parameter level to a fourth primary parameter level when etching the first oxide layer, Methods that include...

6. The method according to claim 5, A method wherein the second primary parameter level is lower than the first primary parameter level, the fourth primary parameter level is lower than the third primary parameter level, the third primary parameter level is higher than the first primary parameter level, and the fourth primary parameter level is higher than the second primary parameter level.

7. The method according to claim 5, further, For the step of etching the first nitrogen-containing layer, a step of supplying a high-frequency RF (HFRF) signal having a first secondary parameter level and a second secondary parameter level, The process involves modifying the first secondary parameter level to a third secondary parameter level and modifying the second secondary parameter level to a fourth secondary parameter level when etching the first oxide layer, Methods that include...

8. The method according to claim 7, A method wherein the second quadratic parameter level is lower than the first quadratic parameter level, the fourth quadratic parameter level is lower than the third quadratic parameter level, the third quadratic parameter level is higher than the first quadratic parameter level, and the fourth quadratic parameter level is higher than the second quadratic parameter level.

9. The method according to claim 8, A method wherein the ratio of the first primary parameter level to the first secondary parameter level is 0.75 to 1.25, and the ratio of the second primary parameter level to the second secondary parameter level is 0.75 to 1.

25.

10. The method according to claim 8, A method wherein the ratio of the third primary parameter level to the third secondary parameter level is 2 to 4, and the ratio of the fourth primary parameter level to the fourth secondary parameter level is 2 to 4.

11. The method according to claim 1, The method wherein the metal-containing gas comprises carbonyl or metal fluoride.

12. The method according to claim 11, The method wherein the metal fluoride is tungsten hexafluoride.

13. The method according to claim 11, The aforementioned metal-containing gas is a fluorocarbon or nitrogen trifluoride (NF 3 A method that is applied in conjunction with ).

14. The method according to claim 1, The method wherein the nonmetallic gas includes hydrofluorocarbons.

15. The method according to claim 1, further, A step of stopping the application of the nonmetallic gas used to etch the second nitrogen-containing layer, A step of applying the metal-containing gas to etch the second oxide layer located beneath the second nitrogen-containing layer, Methods that include...

16. The method according to claim 15, further, When the third nitrogen-containing layer is located below the second oxide layer, and it is determined that a predetermined level has been reached in proximity to the third nitrogen-containing layer, the application of the metal-containing gas used to etch the second oxide layer is stopped. The process involves, after the step of stopping the application of the metal-containing gas used to etch the second oxide layer, applying the non-metallic gas to etch the third nitrogen-containing layer, Methods that include...

17. A controller for etching layers, It is a processor, By applying a nonmetallic gas, the etching of the first nitrogen-containing layer of the laminate is controlled. When it is determined that the first oxide layer below the first nitrogen-containing layer has been reached, the application of the nonmetallic gas is stopped. By applying a metal-containing gas, the etching of the first oxide layer is controlled. When it is determined that the second nitrogen-containing layer beneath the first oxide layer will be reached, the application of the metal-containing gas is stopped. A processor configured to control the etching of the second nitrogen-containing layer by applying the nonmetallic gas, A memory device connected to the aforementioned processor, A controller equipped with the following features.

18. A controller according to claim 17, The application of the nonmetallic gas is controlled until a recess is formed in the first oxide layer, and the application of the nonmetallic gas is stopped when it is determined that the recess has been formed in the first oxide layer, according to the controller.

19. A controller according to claim 17, The aforementioned processor, To etch the first nitrogen-containing layer, the LFRF generator is controlled to supply a low-frequency radio frequency (LFRF) signal having a first primary parameter level and a second primary parameter level. In order to etch the first oxide layer, the first primary parameter level is modified to the third primary parameter level, and the second primary parameter level is modified to the fourth primary parameter level. A controller configured in such a way.

20. A controller according to claim 19, The aforementioned processor, To etch the first nitrogen-containing layer, the HFRF generator is controlled to supply a high-frequency (HF) RF signal having a first secondary parameter level and a second secondary parameter level. When the first oxide layer is etched, the first secondary parameter level is modified to the third secondary parameter level, and the second secondary parameter level is modified to the fourth secondary parameter level. A controller configured in such a way.

21. A plasma system for etching layers, A first gas source configured to store a metal-containing gas, A second gas source configured to store non-metallic gases, A plasma chamber connected to the first gas source via a first gas line and connected to the second gas source via a second gas line, A host computer connected to the first gas line and the second gas line, By applying the nonmetallic gas, the etching of the first nitrogen-containing layer of the laminate is controlled. When it is determined that the first oxide layer below the first nitrogen-containing layer has been reached, the application of the nonmetallic gas is stopped. By applying the metal-containing gas, the etching of the first oxide layer is controlled. When it is determined that the second nitrogen-containing layer beneath the first oxide layer will be reached, the application of the metal-containing gas is stopped. A host computer configured to control the etching of the second nitrogen-containing layer by applying the nonmetallic gas, A plasma system equipped with [the necessary components].

22. The plasma system according to claim 21, further, An LFRF generator configured to generate low-frequency radio frequency (LFRF) signals, An HFRF signal configured to generate a high-frequency RF signal, The LFRF generator and the impedance matching circuit connected to the HFRF generator, wherein the impedance matching circuit is configured to receive the LFRF signal and the HFRF signal and output a modified RF signal, the plasma chamber is connected to the impedance matching circuit to receive the modified RF signal, and the host computer is To etch the first nitrogen-containing layer, the LFRF generator is controlled to supply an LFRF signal having a first primary parameter level and a second primary parameter level. In order to etch the first oxide layer, the first primary parameter level is modified to the third primary parameter level, and the second primary parameter level is modified to the fourth primary parameter level. To etch the first nitrogen-containing layer, the HFRF generator is controlled to supply an HFRF signal having a first secondary parameter level and a second secondary parameter level. An impedance matching circuit is configured to modify the first secondary parameter level to a third secondary parameter level and the second secondary parameter level to a fourth secondary parameter level in order to etch the first oxide layer. A plasma system equipped with [the necessary components].

23. A method for etching a layer, A process of etching the oxide layer by applying a metal-containing gas, When it is determined that the silicon-containing layer beneath the oxide layer has been reached, the application of the metal-containing gas is stopped. A step of etching the silicon-containing layer by applying a nonmetallic gas, Methods that include...

24. The method according to claim 23, A method wherein the oxide layer is reached when the oxide layer is being etched, and is etched when it reaches a predetermined depth from the top surface of the oxide layer.

25. The method according to claim 23, The method wherein the silicon-containing layer is a silicon nitride layer or a polysilicon layer.

26. The method according to claim 23, The method wherein the metal-containing gas comprises carbonyl or metal fluoride.

27. The method according to claim 26, The method wherein the metal fluoride is tungsten hexafluoride.

28. The method according to claim 23, The aforementioned metal-containing gas is a fluorocarbon or nitrogen trifluoride (NF 3 A method that is applied in conjunction with ).

29. The method according to claim 23, The method wherein the nonmetallic gas includes hydrofluorocarbons.

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