Method for controlling interlayer thickness in multilayer epitaxial processes

Abstract

A method for substrate processing includes flowing one or more process reactive gases into an upper volume of a processing chamber, flowing a cleaning gas into a lower volume of the processing chamber, measuring a temperature of an inner surface of the lower volume of the processing chamber, and adjusting the temperature of the inner surface of the lower volume of the processing chamber based on the measured temperature.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The embodiments described herein relate generally to semiconductor device manufacturing, and more particularly to methods and systems for multi-layer epitaxial deposition processes. [Background technology]

[0002] The transition from two-dimensional (2D) to three-dimensional (3D) architectures is expected to bring about a turning point in dynamic random access memory (DRAM) technology. This transition will lead to an increase in DRAM density (Gb / mm 2 ) is needed to meet the ever-increasing demand for

[0003] A key step in the semiconductor fabrication process for these 3D devices is the epitaxial deposition of a stack of alternating layers of Si and SiGe. These alternating layers can typically extend over 100 pairs in height. Each of these layers must meet strict requirements regarding its individual thickness.

[0004] Drift in the chamber thermal environment during stack deposition can cause each layer thickness to deviate outside of its bounds, which can be captured by chamber sensors, such as temperature and power traces.

[0005] Therefore, there is a need for a method and system that reduces drift in the chamber thermal environment during a multi-layer epitaxial deposition process. Summary of the Invention

[0006] Embodiments of the present disclosure provide a method for substrate processing that includes flowing one or more process reactive gases into an upper volume of a processing chamber, flowing a cleaning gas into a lower volume of the processing chamber, measuring a temperature of an inner surface of the lower volume of the processing chamber, and adjusting the temperature of the inner surface of the lower volume of the processing chamber based on the measured temperature.

[0007] Embodiments of the present disclosure also provide a method for substrate processing, the method including performing an epitaxial deposition process to deposit a layer on a surface of a substrate supported on a front surface of a substrate support disposed in an upper volume of a processing chamber, and performing a coating removal process to remove a coating on an interior surface of a lower volume of the processing chamber, the lower volume being opposite the substrate support from the front surface.

[0008] An embodiment of the present disclosure further provides a substrate processing system including: a processing chamber including an upper window, a lower window, a substrate support disposed between the upper and lower windows, a processing volume between a front surface of the substrate support and the upper window, a purge volume between a back surface of the substrate support and the lower window, and a temperature sensor disposed on the lower window, and a controller including instructions that, when executed, cause processes to be performed, the processes including performing an epitaxial deposition process to deposit a layer on a surface of a substrate supported on the front surface of the substrate support, performing a coating removal process to remove a coating on an inner surface of the lower window, performing a temperature monitoring process to measure a temperature of the inner surface of the lower window, and performing a temperature control process to adjust the temperature of the inner surface of the lower window based on the measured temperature.

[0009] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above may be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered limiting of its scope, since the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a schematic cross-sectional view of a system for substrate processing, according to one implementation. [Figure 2] FIG. 1 is a schematic block diagram of a method for controlling interlayer thickness in a multi-layer epitaxial process, according to some embodiments. [Figure 3A] FIG. 1 depicts a comparison of temperature variations in an exemplary multi-layer epitaxial growth process. [Figure 3B] 1A-1C depict a comparison of system power provided to heat sources to control the temperature of an exemplary multi-layer epitaxial growth process. DETAILED DESCRIPTION OF THE INVENTION

[0011] For ease of understanding, like reference numerals have been used, where possible, to designate like elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012] Embodiments described herein provide systems and methods for multilayer epitaxial deposition with mitigated drift in the chamber thermal environment, reducing inter-layer non-uniformity in a deposition stack of alternating Si and SiGe layers. Drift in the chamber thermal environment is reduced by controlling the temperature and flow of gases in the lower volume of the chamber.

[0013] Current basic multilayer epitaxial processes use a pyrometer disposed in the upper volume of the chamber to control the substrate temperature. This creates inherent instability in temperature control because the signal from the pyrometer is affected by the growing layer. In addition, small amounts of deposition gas can leak into the lower volume of the chamber and form a coating on the lower volume of the chamber. The signal from the pyrometer disposed in the lower volume of the chamber is affected by the coating, which also makes controlling the substrate temperature with a pyrometer in the lower volume unstable.

[0014] In the embodiments described herein, temperature control uses a pyrometer disposed in the lower volume of the chamber, and simultaneously, large volumes of cleaning and / or purging gas are flowed into the lower volume of the chamber to keep it free of coating. The combination of these two operations eliminates inherent instabilities in temperature control.

[0015] 1 is a schematic cross-sectional view of a system 100 for substrate processing, according to one embodiment. The system 100 includes a processing chamber 102. In one or more embodiments, the processing chamber 102 is a deposition chamber. In one embodiment, which may be combined with other embodiments, the processing chamber 102 is an epitaxial deposition chamber. The processing chamber 102 is utilized to grow an epitaxial film on a substrate W. The processing chamber 102 is used to deposit a film on the surface W of the substrate W. s A cross flow of precursors is created across the

[0016] The processing chamber 102 includes an upper body 104, a lower body 106 disposed below the upper body 104, and a flow module 108 disposed between the upper body 104 and the lower body 106. The upper body 104, the flow module 108, and the lower body 106 form a chamber body. Disposed within the chamber body are a substrate support 110, an upper window 112 (e.g., an upper dome), a lower window 114 (e.g., a lower dome), an upper heat source 116, and a lower heat source 118.

[0017] The substrate support 110 is disposed between an upper window 112 and a lower window 114. The substrate support 110 includes a front surface 120 that faces the upper window 112 and supports a substrate W. The upper heat source 116 is disposed between the upper window 112 and a lid 122. The lower heat source 118 is disposed between the lower window 114 and a floor 124. The upper window 112 is an upper dome and is formed from an energy-transparent material such as quartz. The lower window 114 is a lower dome and is formed from an energy-transparent material such as quartz.

[0018] 1, the heat sources 116, 118 are lamps. Other heat sources are contemplated, such as resistive heaters, light emitting diodes (LEDs), and / or lasers.

[0019] The processing chamber 102 may include one or more temperature sensors 126, 128, such as optical pyrometers, that measure the temperature within the processing chamber 102. The temperature sensor 126 (e.g., a top pyrometer) may be disposed above the upper window 112. The temperature sensor 128 (e.g., a bottom pyrometer) may be disposed below the lower window 114.

[0020] A processing volume 130 (also referred to as the “upper volume”) and a purge volume 132 (also referred to as the “lower volume”) are formed between the upper window 112 and the lower window 114. The processing volume 130 and the purge volume 132 are part of an interior volume that is at least partially defined by the upper window 112, the lower window 114, and one or more liners 134.

[0021] The interior volume has a substrate support 110 disposed therein. The purge volume 132 is opposite the substrate support 110 from the front face 120 and the substrate W disposed thereon. The substrate support 110 is attached to a shaft 136. The shaft 136 is connected to a motion assembly 138. The motion assembly 138 includes one or more actuators and / or adjustment devices that provide movement and / or adjustment to the shaft 136 and / or the substrate support 110 within the processing volume 130.

[0022] The substrate support 110 may include lift pin holes 140 disposed therein. The lift pin holes 140 are sized to accommodate lift pins 142 for lowering and / or raising the substrate W from the substrate support 110 before and / or after a deposition process is performed. The lift pins 142 may rest on lift pin stops 144 when the substrate support 110 is lowered from the process position to the transfer position.

[0023] The flow module 108 includes a process inlet passage 146 in fluid communication with the processing volume 130 and a purge inlet passage 148 in fluid communication with the purge volume 132. The flow module 108 further includes a process outlet passage 150 in fluid communication with the processing volume 130 and a purge outlet passage 152 in fluid communication with the purge volume 132. The process inlet passage 146 and the purge inlet passage 148 are disposed on the opposite side of the flow module 108 from the process outlet passage 150 and the purge outlet passage 152. One or more flow guides 154 are disposed below the process inlet passage 146 and the process outlet passage 150. The one or more flow guides 154 are disposed above the purge inlet passage 148. In one or more embodiments, the one or more flow guides 154 include a preheat ring. One or more liners 134 are disposed on the interior surfaces of the flow module 108 to protect the flow module 108 from reactive gases used during deposition and / or cleaning processes. A process inlet passage 146 and a purge inlet passage 148 each provide a passageway between the surface W of a substrate W disposed within the processing volume 130 and the flow module 108. s The process inlet passage 146 and the purge inlet passage 148 are positioned to flow gases parallel to the process chamber 102. The process inlet passage 146 and the purge inlet passage 148 are fluidly connected to a gas supply system 156 that regulates the gases supplied to the processing chamber 102. One or more process gas sources 158, one or more cleaning gas sources 160, and one or more purge gas sources 162 are fluidly connected to the gas supply system 156. In one or more embodiments, the one or more process gas sources 158 include one or more reactive gas sources and one or more carrier gas sources.

[0024] The process outlet passage 150 and the purge outlet passage 152 are fluidly connected to an exhaust pump 164 (eg, a vacuum pump).

[0025] The one or more process gases supplied to the gas supply system 156 using the one or more process gas sources 158 may include one or more reactive gases (such as one or more of silicon (Si), phosphorus (P), and / or germanium (Ge)) and / or one or more carrier gases (such as one or more of nitrogen (N) and / or hydrogen (H)). The one or more purge gases supplied using the one or more purge gas sources 162 may include one or more inert gases (such as one or more of hydrogen (H), argon (Ar), helium (He), and / or nitrogen (N)). The one or more cleaning gases supplied using the one or more cleaning gas sources 160 may include one or more of hydrogen (H) and / or chlorine (Cl). In one embodiment, which may be combined with other embodiments, the one or more process gases include silicon phosphide (SiP) and / or phosphine (PH), and the one or more cleaning gases include hydrochloric acid (HCl). The present disclosure contemplates that carrier gases, purge gases, and / or cleaning gases are all candidates for recycling as described herein.

[0026] As shown, system 100 includes a controller 166 in communication with processing chamber 102. Controller 166 is used to control processes and methods, such as the method steps described herein. Controller 166 is in communication with exhaust pump 164 and gas supply system 156. Controller 166 controls exhaust gases (exhausted from processing chamber 102) using sensors disposed along exhaust pump 164 and / or gas supply system 156. By monitoring the purity content of the gases, controller 166 can control gas supply system 156 to determine (and control) where the gases flow in system 100.

[0027] The controller 166 includes a central processing unit (CPU), memory containing instructions, and support circuits for the CPU. The controller 166 controls various items directly or through other computers and / or controllers. In one or more embodiments, the controller 166 is communicatively coupled to a dedicated controller, and the controller 166 functions as a central controller.

[0028] The controller 166 may be any form of general-purpose computer processor and sub-processors thereon or therein used in industrial environments to control various substrate processing chambers and equipment. The memory, or non-transitory computer-readable medium, may be one or more of readily available memory such as random access memory (RAM), dynamic random access memory (DRAM), static RAM (SRAM), and synchronous dynamic RAM (SDRAM (e.g., DDR1, DDR2, DDR3, DDR3L, LPDDR3, DDR4, LPDDR4, etc.)), read-only memory (ROM), floppy disk, hard disk, flash drive, or any other form of digital storage, local or remote. Support circuits of the controller 166 are coupled to the CPU (processor) to support the CPU. The support circuits include cache, power supplies, clock circuits, input / output circuits and subsystems, etc. The process parameters (recycle gas pressure, recycle gas purity, recycle gas chemical composition) and operations are stored in memory as software routines that are executed or called to transform the controller 166 into a special-purpose controller for controlling the operation of the various systems / chambers / recycle systems / modules described herein. The controller 166 is configured to perform any of the processes described herein. The instructions stored in memory, when executed, cause one or more of the steps of method 200 (described below) to be performed.

[0029] The various operations described herein may be performed automatically using the controller 166, or may be performed automatically and / or manually by specific actions taken by a user.

[0030] The controller 166 is configured to adjust the output to control the system 100 based on the sensor readings, the system model, and the stored readings and calculations. The controller 166 includes built-in software and compensation algorithms for calibrating measurements. The controller 166 may include one or more machine learning and / or artificial intelligence algorithms that estimate optimized parameters for the deposition, purging, and / or cleaning processes. The one or more machine learning and / or artificial intelligence algorithms may, for example, use regression models (such as linear regression models) or clustering techniques to estimate the optimized parameters. The algorithms may be unsupervised or supervised.

[0031] In one or more embodiments, the gas supply system 156 is responsible for providing all gases to the processing chamber 102, regardless of which gas sources 158, 160, 162 supply the gases. The gas supply system 156 is controlled by a controller 166.

[0032] FIG. 2 is a schematic block diagram of a method 200 for controlling interlayer thickness in a multi-layer epitaxial process using a substrate processing system, such as the system 100 shown in FIG. 1, according to some embodiments.

[0033] The method 200 begins at block 210, where an epitaxial deposition process is performed on the surface W of a substrate W supported on the front surface 120 of a substrate support 110 disposed in the processing volume 130 of the processing chamber 102. sThe epitaxial deposition process involves flowing one or more reactive gases from one or more process gas sources 158 into the processing volume 130 of the processing chamber 102. The one or more reactive gases enter the processing volume 130 through a process inlet passage 146 above one or more flow guides 154 and exit through a process outlet passage 150.

[0034] The layers deposited in block 210 may be alternating layers of a first material (e.g., silicon (Si)) and a second material (e.g., silicon germanium (SiGe)). Each layer may have a thickness between about 50 Å and about 1000 Å. The number of pairs of layers of the first material and the second material is three or more.

[0035] In some embodiments, the one or more reactive gases include a deposition gas and a carrier gas. The deposition gas includes a silicon- or germanium-containing precursor and a dopant source. The dopant source may include precursors such as phosphine (PH), phosphorus trichloride (PCl), triisobutylphosphine ([(CH)C]P), arsine (AsH), arsenic trichloride (AsCl), tertiarybutylarsine (AsCH), and n-type dopants such as phosphorus (P), arsenic (As), or antimony (Sb). 11 ), antimony trichloride (SbCl3), or Sb(C2H5)5. The dopant source may include the precursor diborane (B2H6), or trimethylgallium (Ga(CH3)3), which includes a p-type dopant such as boron (B) or gallium (Ga). The carrier gas may include nitrogen (N2), argon (Ar), helium (He), or hydrogen (H2).

[0036] During the epitaxial deposition process, some of the deposition gas may leak into the purge volume 132 between the flow guide 154 and the substrate support 110 and form a coating on the inner surfaces of the purge volume 132 (e.g., the back surface 110A of the substrate support 110 and the inner surface 114A of the lower window 114, as shown in FIG. 1 ). Because the epitaxial deposition process may be time-consuming (e.g., deposition of 100 pairs of silicon (Si) and silicon germanium (SiGe) layers), the coating may build up. This coating may cause inaccurate temperature measurements by the temperature sensor 128 (e.g., a bottom pyrometer) disposed on the lower window 114. Therefore, the coating is removed or prevented in block 220.

[0037] In block 220, simultaneously with block 210, a coating removal process is performed to reduce coatings on the inner surfaces of the purge volume 132 (e.g., the backside 110A of the substrate support 110 and the inner surface 114A of the lower window 114). The coating removal process includes flowing a purge gas from one or more purge gas sources 162 or a cleaning gas from one or more cleaning gas sources 160 through the purge volume 132 of the processing chamber 102 via the purge inlet passage 148 and the purge outlet passage 152. The purge gas may include hydrogen (H) at a flow rate greater than 2 standard liters per minute (slm) to dilute the portion of the deposition gas flowed into the purge volume 132 and prevent the formation of a coating on the backside 110A of the substrate support 110 and the inner surface 114A of the lower window 114. The cleaning gas may include a chlorine-containing etchant gas to remove coatings formed on the backside 110A of the substrate support 110 and the inner surface 114A of the lower window 114. The purge or cleaning gas can be prevented from leaking into the processing volume 130, which could interfere with the epitaxial deposition process, because the purge or cleaning gas flows through the purge volume 132 via the purge inlet passage 148 and the purge outlet passage 152 below the flow guide 154.

[0038] In block 230, a temperature monitoring process is performed to measure the temperature of the inner surface of the purge volume 132 (e.g., the lower window 114) by a temperature sensor 128 (e.g., a bottom pyrometer) disposed on the lower window 114. The temperature measured at the back surface 110A of the substrate support 110, which is the opposite side of the substrate support 110 from the substrate W disposed thereon, may not be affected by film growth on the substrate W. Furthermore, the temperature measured at the back surface 110A of the substrate support 110 may not be affected by a coating on the back surface 110A of the substrate support 110 or on the inner surface 114A of the lower window 114, because the coating was prevented or removed in block 220.

[0039] In block 240, a temperature control process is performed to adjust the temperature at the inner surface of the purge volume 132 (e.g., lower window 114) by adjusting the power provided to the upper heat source 116 and the lower heat source 118 based on the temperature measured at the inner surface of the purge volume 132 (e.g., lower window 114) on the opposite side of the substrate support 110 from the substrate W disposed thereon in block 230. Various gas flow rates may also be adjusted to control the temperature at the lower window 114. [Example]

[0040] 3A illustrates the temperature change of an exemplary multilayer epitaxial growth process, in which the temperature is controlled by a temperature sensor 126 (e.g., a top pyrometer) disposed on the upper window 112, thereby maintaining a constant temperature at the upper window 112. Temperature change 302 illustrates the change in temperature measured at the backside of 110 when the coating removal process in block 220 is not performed. Temperature change 304 illustrates the change in temperature measured at the backside of 110 when the coating removal process in block 220 is performed, in which the cleaning gas includes a chlorine-containing etchant gas. Because the coating is at least partially removed from the inner surface 114A of the lower window 114, the temperature drop is reduced. Temperature change 306 illustrates the change in temperature measured at the backside of 110 when the coating removal process in block 220 is performed, in which the cleaning gas is flowed at a higher flow rate than in temperature change 306. The temperature drop is reduced compared to temperature change 304.

[0041] 3B depicts the system power provided to the heat sources 116 and 118 to control the temperature of an exemplary multi-layer epitaxial growth process. System power change 308 illustrates the system power that needed to be provided to the heat sources 116 and 118 when the temperature was monitored by the temperature sensor 126 (e.g., a top pyrometer) at the upper window 112. System power change 310 illustrates the system power that needed to be provided to the heat sources 116 and 118 when the temperature was monitored by the temperature sensor 128 (e.g., a bottom pyrometer) disposed on the lower window 114 (as in block 230) and the coatings on the back surface 110A of the substrate support 110 and the inner surface 114A of the lower window 114 were at least partially removed (as in block 220). Because the signal from the temperature sensor 128 (e.g., bottom pyrometer) does not interfere with the epitaxial growth on the substrate on the substrate support 110 or with the coating on the back surface 110A of the substrate support 110 and the inner surface 114A of the lower window 114, the power variation is minimized and significantly reduced compared to 308.

[0042] The embodiments described herein provide systems and methods for multilayer epitaxial deposition in which drift in the chamber thermal environment is mitigated. Temperature control uses a temperature sensor disposed on the lower volume of the processing chamber, while large volumes of cleaning and / or purge gas are flowed into the lower volume of the chamber to keep it free of coatings. Inherent instabilities in temperature control are thereby eliminated, resulting in reduced layer-to-layer non-uniformity in the deposition stack of alternating Si and SiGe layers.

[0043] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. flowing one or more process reactive gases into an upper volume of the processing chamber; flowing a cleaning gas into a lower volume of the processing chamber; measuring the temperature of the interior surface of the lower volume of the processing chamber; adjusting the temperature of the interior surface of the lower volume of the processing chamber based on the measured temperature; 1. A method for processing a substrate, comprising:

2. 10. The method of claim 1, wherein flowing the one or more process reactive gases into the upper volume of the processing chamber and flowing the cleaning gas into the lower volume of the processing chamber are performed simultaneously.

3. The method of claim 1 , wherein the one or more process reactive gases comprise a silicon or germanium-containing precursor.

4. 4. The method of claim 3, wherein the layers deposited by flowing the one or more process reactive gases comprise three or more pairs of alternating layers of silicon (Si) and silicon germanium (SiGe), each layer having a thickness between 50 Å and 1000 Å.

5. The cleaning gas is hydrogen (H ２ ) a purge gas.

6. The hydrogen (H ２ 6. The method of claim 5, wherein: 1.) the flow rate of the purge gas is greater than 2 slm.

7. The method of claim 1 , wherein the cleaning gas comprises a chlorine-containing etchant gas.

8. conducting an epitaxial deposition process to deposit a layer on a surface of a substrate supported on a front surface of a substrate support disposed in an upper volume of the processing chamber; performing a coating removal process to remove a coating on an interior surface of a lower volume of the processing chamber, the lower volume being on an opposite side of the substrate support from the front surface; 1. A method for processing a substrate, comprising:

9. conducting a temperature monitoring process to measure the temperature of the interior surface of the lower volume of the processing chamber; performing a temperature control process to adjust the temperature of the interior surface of the lower volume of the processing chamber based on the measured temperature; The method of claim 8 further comprising:

10. 10. The method of claim 8, wherein the epitaxial deposition process comprises flowing one or more process reactive gases into the upper volume of the processing chamber.

11. The method of claim 10 , wherein the one or more process reactive gases comprise a silicon or germanium-containing precursor.

12. 12. The method of claim 11, wherein the layers deposited in the epitaxial deposition process include three or more pairs of alternating layers of silicon (Si) and silicon germanium (SiGe), each layer having a thickness between 50 Å and 1000 Å.

13. The coating removal process involves passing hydrogen (H ２ 9. The method of claim 8, comprising: flowing a purging gas through the nozzle.

14. The hydrogen (H ２ 14. The method of claim 13, wherein: a flow rate of the purge gas is greater than 2 slm.

15. 9. The method of claim 8, wherein the coating removal process comprises flowing a chlorine-containing etchant gas through the lower volume of the processing chamber.

16. The upper window and The lower window and a substrate support disposed between the upper window and the lower window; a processing volume between a front surface of the substrate support and the upper window; a purge volume between the backside of the substrate support and the lower window; a temperature sensor disposed on the lower window; a processing chamber comprising: A controller comprising instructions that, when executed, cause a process to be performed, said process comprising: performing an epitaxial deposition process to deposit a layer on a surface of a substrate supported on the front surface of the substrate support; performing a coating removal process to remove a coating on the interior surface of the lower window; performing a temperature monitoring process to measure the temperature of the inner surface of the lower window; executing a temperature control process to adjust the temperature of the inner surface of the lower window based on the measured temperature; Including the controller and A substrate processing system comprising:

17. the epitaxial deposition process includes flowing one or more process reactive gases into the process volume of the processing chamber; the one or more process reactive gases comprise a silicon or germanium-containing precursor; the layers deposited in the epitaxial deposition process include three or more pairs of alternating layers of silicon (Si) and silicon germanium (SiGe), each layer having a thickness between 50 Å and 1000 Å; The substrate processing system of claim 16.

18. the processing chamber a purge inlet passage in fluid communication with the purge volume; a purge outlet passage in fluid communication with the purge volume; The substrate processing system of claim 16 further comprising:

19. The coating removal process includes passing hydrogen (H ) through the purge volume via the purge inlet passage and the purge outlet passage. ２ 20. The substrate processing system of claim 18, further comprising: flowing a purging gas.

20. 20. The substrate processing system of claim 18, wherein the coating removal process comprises flowing a chlorine-containing etchant gas through the purge volume via the purge inlet passage and the purge outlet passage.

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