WO2024000732A1

WO2024000732A1 - Process equipment cleaning method

Info

Publication number: WO2024000732A1
Application number: PCT/CN2022/110350
Authority: WO
Inventors: 王怀庆; 陈铭
Original assignee: 长鑫存储技术有限公司
Priority date: 2022-06-28
Filing date: 2022-08-04
Publication date: 2024-01-04
Also published as: CN117339946A

Abstract

A process equipment cleaning method, which is used for cleaning a furnace tube used in a diffusion process, wherein the surface of a working face of the furnace tube comprises a silicon dioxide film generated in the diffusion process. The method comprises: heating a first component group of the furnace tube to a first temperature, wherein the first component group comprises a vacuum pipeline and a flange; introducing hydrogen fluoride gas into the furnace tube to remove the silicon dioxide film generated on the surface of the working face of the first component group; heating a second component group of the furnace tube to a second temperature, wherein the second component group comprises a quartz tube and a quartz boat, and the second temperature is higher than the first temperature; introducing fluorine gas into the furnace tube to remove a silicon dioxide film generated on the surface of the working face of the second component group; and introducing an inactive gas into the furnace tube, and vacuumizing the furnace tube. The embodiments of the present disclosure can improve the cleaning efficiency of the furnace tube used in the diffusion processes, and reduce the loss of the furnace tube. (FIG. 2)

Description

Process equipment cleaning methods

cross reference

This disclosure claims priority to the Chinese patent application with application number 202210753429.2 and titled "Process Equipment Cleaning Method" filed on June 28, 2022. The entire content of this Chinese patent application is incorporated herein by reference.

Technical field

The present disclosure relates to the technical field of integrated circuit manufacturing, and specifically to a method for cleaning process equipment.

Background technique

In the field of integrated circuit manufacturing, depositing oxide to form process layers is a common process. The types of oxides commonly used in oxide deposition processes include silicon dioxide, TEOS (tetraethoxysilicate, also known as tetraethoxy silicon, Si(OC2H5)4), etc.

TEOS is a colorless and transparent liquid with a slight odor. It can decompose to generate silica and organic matter at temperatures above 700°C and under low pressure and oxygen conditions. Therefore, the wafer to be deposited is usually placed on a quartz boat, and the quartz boat is placed in a process furnace tube that can achieve high-temperature heating to achieve TEOS silicon dioxide diffusion deposition, which results in the working surface of the process furnace tube in the TEOS diffusion process. The surface (inner wall) is often covered with a silica film, and the silica film needs to be cleaned regularly.

In related technologies, wet cleaning (such as WET PM, maintenance work of quartz products) is usually used to clean the furnace tubes. When cleaning, you first need to remove many quartz products on the furnace tube, including quartz tube (Tube), quartz boat (Boat), quartz plate (Plate), etc. Then, the dismantled quartz products are immersed in a quartz cleaning agent for wet cleaning. The quartz cleaning agent is usually a hydrogen fluoride (HF) liquid.

This cleaning method requires dismantling the furnace tube, which is inefficient and will damage the non-working surface (outer wall) of the furnace tube, causing an increase in integrated circuit manufacturing costs.

It should be noted that the information disclosed in the above background section is only used to enhance understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to those of ordinary skill in the art.

Contents of the invention

The purpose of the present disclosure is to provide a method for cleaning process equipment, which is used to overcome, at least to a certain extent, the problems of low efficiency and loss of the process furnace tube itself during the cleaning process of the process furnace tube.

According to a first aspect of the present disclosure, a process equipment cleaning method is provided for cleaning a furnace tube used in a diffusion process. The working surface of the furnace tube includes a silicon dioxide film generated in the diffusion process, and the The method includes: heating a first component group of the furnace tube to a first temperature, the first component group including a vacuum pipe and a flange; passing hydrogen fluoride gas into the furnace tube to remove the first component The silicon dioxide film generated on the working surface of the group; the second component group of the furnace tube is heated to a second temperature, the second component group includes a quartz tube and a quartz boat, and the second temperature is higher than the the first temperature; passing fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group; passing inert gas into the furnace tube and vacuuming.

In an exemplary embodiment of the present disclosure, passing fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group includes: supplying fluorine gas to the furnace tube. Pure fluorine gas is passed through to remove the silica film generated on the working surface of the second component group.

In an exemplary embodiment of the present disclosure, after the fluorine gas is introduced into the furnace tube and before the inert gas is introduced into the furnace tube, the method further includes: when the preset condition occurs, the method further includes: The diluted fluorine gas is passed into the furnace tube.

In an exemplary embodiment of the present disclosure, introducing diluted fluorine gas into the furnace tube when a preset condition occurs includes: monitoring the temperature of the second component group, and when the second When the temperature rise rate of the component group reaches the first preset rate, diluted fluorine gas is introduced into the furnace tube; when the temperature rise rate of the second component group drops to the second preset rate, Stop introducing diluted fluorine gas.

In an exemplary embodiment of the present disclosure, the first preset rate is 8-10°C/min; and/or the second preset rate is 0-1°C/min.

In an exemplary embodiment of the present disclosure, the diluted fluorine gas includes inert gas and fluorine gas, and the inert gas includes nitrogen and/or inert gas.

In an exemplary embodiment of the present disclosure, in the diluted fluorine gas, the volume ratio of the inert gas and the fluorine gas is 1: (1-5).

In an exemplary embodiment of the present disclosure, the introducing hydrogen fluoride gas into the furnace tube includes: introducing hydrogen fluoride gas into the furnace tube for a first preset time period; Injecting fluorine gas into the tube includes: injecting fluorine gas into the furnace tube for a second preset time period.

In an exemplary embodiment of the present disclosure, the method further includes: determining a first thickness of the silicon dioxide film generated on the working surface of the first component group and two thicknesses of the silicon dioxide film generated on the working surface of the second component group. The second thickness of the silicon oxide film; the first preset time length is determined based on the first thickness, and the second preset time length is determined based on the second thickness.

In an exemplary embodiment of the present disclosure, the determination of the first thickness of the silicon dioxide film generated on the working surface of the first component group and the determination of the first thickness of the silicon dioxide film generated on the working surface of the second component group The second thickness of the silicon film includes: measuring the first thickness and the second thickness through an elemental analyzer; or determining the first thickness and the second thickness according to parameters of the previous process conditions.

In an exemplary embodiment of the present disclosure, the introduction of hydrogen fluoride gas into the furnace tube includes: monitoring the thickness of the silicon dioxide film generated on the working surface of the first component group. When the thickness of the silicon dioxide film on the working surface of a module group is less than the preset thickness, the flow of hydrogen fluoride gas is stopped.

In an exemplary embodiment of the present disclosure, the preset thickness is 0-5 μm.

In an exemplary embodiment of the present disclosure, heating the second component group of the furnace tube to the second temperature includes: starting to heat the second component group after stopping the flow of hydrogen fluoride gas; or, The heating of the second component group is started before the flow of hydrogen fluoride gas is stopped, and the temperature of the second component group is lower than the temperature of the first component group when the flow of hydrogen fluoride gas is stopped.

In an exemplary embodiment of the present disclosure, introducing inert gas into the furnace tube and evacuating the vacuum includes: after stopping the introduction of fluorine gas, introducing inert gas into the furnace tube and evacuating the furnace tube. Evacuate, and detect the gas in the furnace tube to determine whether it contains fluorine ions; when it is detected that it contains fluorine ions, repeatedly introduce the inactive gas and evacuate, and repeatedly check the gas in the furnace tube. The gas is detected until no fluoride ions are detected; the introduction of the inactive gas and the vacuuming operation are stopped.

In an exemplary embodiment of the present disclosure, the first temperature is not less than 40°C and not greater than 100°C; and/or the second temperature is not less than 200°C.

In an exemplary embodiment of the present disclosure, the first temperature ranges from 75°C to 100°C; and/or the second temperature ranges from 400°C to 500°C.

By heating different parts of the furnace tube to different temperatures and then passing different gases into the furnace tube, the embodiments of the present disclosure can remove the working surface of each part of the furnace tube generated in the diffusion process without dismantling the furnace tube. The silicon dioxide film will not cause damage to the non-working surface of the furnace tube, which can effectively improve the cleaning efficiency of the process furnace tube and reduce the cost of integrated circuit manufacturing. The disclosed process equipment cleaning method, that is, the gas decomposition dry cleaning method, can replace the traditional disassembly and water cleaning method, increase equipment utilization, reduce operating costs, avoid human errors, and can be widely used in the maintenance of semiconductor equipment.

It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and do not limit the present disclosure.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic diagram of a part to be cleaned in the related art.

Figure 2 is a flow chart of a process equipment cleaning method in an exemplary embodiment of the present disclosure.

Figure 3 is a schematic structural diagram of a furnace tube in an embodiment of the present disclosure.

FIG. 4 is a schematic diagram of the silicon dioxide film generated on the working surface of the second component group 32 and the cracks generated during the cleaning process.

Figure 5 is a sub-flow chart of step S4 in one embodiment of the present disclosure.

Figure 6 is a sub-flow chart of step S5 in an embodiment of the present disclosure.

Detailed ways

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concepts of the example embodiments. To those skilled in the art. The described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of the specific details described, or other methods, components, devices, steps, etc. may be adopted. In other instances, well-known technical solutions have not been shown or described in detail to avoid obscuring aspects of the disclosure.

In addition, the drawings are only schematic illustrations of the present disclosure, and the same reference numerals in the drawings represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and/or processor devices and/or microcontroller devices.

Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

As mentioned before: In the field of integrated circuit manufacturing, depositing oxide to form process layers is a common process. Types of oxides commonly used in oxide deposition processes include silicon dioxide, TEOS (tetraethoxysilane, Si(OC ₂ H ₅ ) ₄ ), etc.

In related technologies, wet cleaning (such as WET PM, maintenance work of quartz products) is usually used to clean the furnace tubes. When cleaning, you first need to remove many quartz products on the furnace tube, including quartz tube (Tube), quartz boat (Boat), quartz plate (Plate), etc. Then, the dismantled quartz products are immersed in a quartz cleaning agent for wet cleaning. The quartz cleaning agent is usually hydrogen fluoride liquid (HF).

Figure 1 is a schematic diagram of a part to be cleaned in the related art.

Referring to FIG. 1 , the quartz outer tube 100 to be cleaned has a working surface 11 , a non-working surface 12 and a functional surface 13 . In related technologies, when cleaning the quartz outer tube, the entire quartz outer tube needs to be immersed in a hydrofluoric acid (HF) solution. Quartz products react violently in the acid solution. It is difficult to ensure that only the etching products are produced, and the quartz will be over-etched. The product, that is, the hydrofluoric acid solution will cause corrosion damage to the entire quartz piece. When cleaning the silicon dioxide film on the working surface 11, it will cause irreversible damage to the non-working surface 12 and the functional surface 13. However, in actual cleaning requirements, the product only needs to be etched on the working surface 11 instead of causing damage to the quartz product itself.

In addition, since the furnace tube 100 works under low pressure (15pa~40pa), the functional surface 13 needs extremely high flatness to ensure the vacuum degree, and the quartz as a whole needs a certain thickness to withstand atmospheric pressure. Wet cleaning will cause excessive etching of the entire quartz part of the furnace tube 100 and affect the vacuum degree. Repeated cleaning will cause the quartz to become thinner and affect normal use (the service life of wet cleaning is less than 1 year). Therefore, wet cleaning has product potential scrapping risks and reduced service life of quartz parts.

Finally, the hydrofluoric acid solution with a concentration of 40% (5mol/L) will undergo auto-ionization and the etching rate will reach 1.3um/min. At this time, as the reaction continues, the generation of water and impurities will keep the hydrofluoric acid concentration constant. After the solution was diluted, the etching rate of 20% hydrofluoric acid aqueous solution was only 0.5um/min. The instability of the corrosion rate makes the corrosion accuracy of wet cleaning uncontrollable.

Referring to Figure 2, the process equipment cleaning method 200 is used to clean the furnace tube used in the diffusion process. The working surface of the furnace tube includes the silicon dioxide film generated in the diffusion process. The process equipment cleaning method 200 may include:

Step S1, heat the first component group of the furnace tube to the first temperature. The first component group includes the vacuum pipe and the flange;

Step S2: Pass hydrogen fluoride gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the first component group;

Step S3, heating the second component group of the furnace tube to a second temperature. The second component group includes a quartz tube and a quartz boat, and the second temperature is higher than the first temperature;

Step S4, pass fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group;

Step S5: Inject inert gas into the furnace tube and evacuate it.

Next, each step of the process equipment cleaning method 100 is described in detail.

In step S1, a first component group of furnace tubes, including a vacuum pipe and a flange, is heated to a first temperature.

Referring to Figure 3, the furnace tube 300 to be cleaned may include a first component group 31 and a second component group 32, wherein the first component group 31 may include vacuum pipes 311, flanges 312 and other components that operate at lower temperatures; The second component group 32 may include components such as quartz tubes and quartz boats that operate at relatively high temperatures, such as quartz inner tube 321, quartz boat 322, quartz outer tube 323, sealing rings 324 and other components that operate at relatively high temperatures. It can be understood that the first component group 31 may also include other necessary components shown in FIG. 3 , which is not specifically limited by the present disclosure.

Among them, the lower temperature refers to the operating temperature below 100°C, and the higher temperature refers to the operating temperature above 600°C.

Both the first component group 31 and the second component group 32 have corresponding heating devices, which can be heated to different temperatures respectively. The inventor of the present disclosure analyzed that if the first component group 31 and the second component group 32 are heated to the same temperature, the gas will react with both the first component group 31 and the second component group 32 , and the first component group 31 causing irreversible damage to the first component group 31 and the second component group 32, or the thoroughness of cleaning of the first component group 31 and the second component group 32 cannot be guaranteed.

Therefore, the inventor of the present disclosure arranged to heat the first component group 31 and the second component group 32 to different temperatures respectively, and input different gases to achieve separate cleaning of the first component group 31 and the second component group 32 .

In step S2, hydrogen fluoride gas is passed into the furnace tube to remove the silicon dioxide film generated on the working surface of the first component group.

Since the corresponding temperature of the first component group 31 is lower, in order to eliminate the cooling process caused by heating the second component group 32 first, the embodiment of the present disclosure first heats the first component group 31 to the corresponding first temperature instead of heating the second component group 32 first. The two-component set 32 performs heating. In one embodiment, the first temperature is no less than 40°C and no more than 100°C. When the first temperature is within the aforementioned range, the first component group 31 is in a low temperature state, while the second component group 32 is in a room temperature or normal temperature state. At this time, hydrogen fluoride gas is introduced into the furnace tube. The hydrogen fluoride gas is mainly related to the low temperature state. The silicon dioxide film generated on the working surface of the first component group 31 reacts with the hydrogen fluoride gas, while the silicon dioxide film generated on the working surface of the second component group 32 at room temperature or normal temperature hardly reacts with hydrogen fluoride gas. chemical reaction. When the first temperature ranges from 75°C to 100°C, the hydrogen fluoride gas can react faster and better with the silicon dioxide film generated on the working surface of the first component group 31 in a low temperature state, so the preferred embodiment is , the first temperature may range from 75°C to 100°C.

Condensed water vapor is easily formed on the surface of silicon oxide at low temperatures. The key step in the reaction of gas-phase hydrogen fluoride with silicon oxide below 100°C is the generation of fluorine anions (F- or HF ₂ -) in the water vapor. The overall chemical formula of this reaction is as follows:

HF↑+SiO ₂ ＝＝＝＝＝SiF ₄ ↑+H ₂ O (1)

The condition for the above reaction is T1, which is the first temperature.

In one embodiment, in step S2, hydrogen fluoride gas can be introduced into the furnace tube for a first preset time period.

The time for introducing the hydrogen fluoride gas can be determined based on the flow rate of the hydrogen fluoride gas and the thickness of the silicon dioxide film generated on the working surface of the first component group. The flow rate of hydrogen fluoride gas can be determined according to the equipment capacity.

Therefore, when the ventilation time of hydrogen fluoride gas is set to the first preset time length, the first thickness of the silicon dioxide film generated on the working surface of the first component group can be determined first, and then the first preset thickness is determined based on the first thickness. Set duration.

However, in practical applications, as the flow rate changes or the temperature changes, the reaction rate may change. Therefore, in another embodiment, step S2 may include: monitoring the silica film generated on the working surface of the first component group. When the thickness of the silicon dioxide film on the working surface of the first component group is less than the preset thickness, the flow of hydrogen fluoride gas is stopped. The preset thickness may be, for example, 0-5 μm. At this preset thickness, it can be approximately considered that the silicon dioxide film on the working surface of the first component group is basically removed. That is, when the preset thickness is detected, the product silica film on the vacuum pipe and flange in the low-temperature area is basically cleaned, and the material of the vacuum pipe and flange will not chemically react with the hydrogen fluoride gas.

The first thickness measurement of the silicon dioxide film may be measured by an elemental analyzer, or may be determined based on parameters of the previous process conditions. The specific measurement method of the first thickness measurement of the silicon dioxide film is well known to those skilled in the art, and will not be described in detail here.

It should be noted that, as mentioned above, when hydrogen fluoride gas is passed into the furnace tube, the second component group 32 is in a normal temperature state and will not react with the hydrogen fluoride gas. Therefore, by using hydrogen fluoride gas to dry clean the working surface surface of the first component group 31 of the furnace tube, other parts of the furnace tube can be effectively protected from corrosion. At the same time, because the temperature and pressure in the furnace tube are controllable, and the flow rate of hydrogen fluoride gas per minute is controllable, the reaction time is controllable, the reaction process is simple, and the etching accuracy is high.

In step S3, the second component group of the furnace tube is heated to a second temperature. The second component group includes a quartz tube and a quartz boat, and the second temperature is higher than the first temperature.

In step S4, fluorine gas is passed into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group.

Since the second component group 32 is the main implementation location of the diffusion process and has a relatively high operating temperature, the second temperature is not less than 200°C. In one embodiment, the second temperature ranges from 400°C to 500°C. At a temperature of not less than 200°C, the silica film generated between the fluorine gas and the working surface of the second component group can have a higher reaction rate. In order to balance the high reaction rate and low cost, in a preferred embodiment , the second temperature may range from 400°C to 500°C.

In an exemplary embodiment of the present disclosure, step S3 may include: starting to heat the second component group 32 after stopping the flow of hydrogen fluoride gas.

In an exemplary embodiment of the present disclosure, step S3 may include: starting to heat the second component group 32 before stopping the flow of hydrogen fluoride gas, and the temperature of the second component group 32 is lower than that of the first component when the flow of hydrogen fluoride gas is stopped. Group 31 temperature.

Controlling the start time of heating the second component group 32 before stopping the flow of hydrogen fluoride gas can improve the efficiency of the cleaning process and avoid wasting time caused by waiting for the heating process. During advance heating, controlling the temperature of the second component group 32 during the heating process can control the reaction rate of the second component group 32 with the hydrogen fluoride gas during the process of introducing the hydrogen fluoride gas in step S2.

By controlling the temperature of the second component group 32 to be heated in advance, the hydrogen fluoride gas can be stopped at the end of step S2, that is, after it is detected that the product silica film on the vacuum pipe and flange in the low temperature area has been cleaned, Immediately introduce fluorine gas to clean the working surface of the second component group 32.

Fluorine gas is very corrosive and has extremely active chemical properties. It is one of the most oxidizing substances. It can even react with some inert gases under certain conditions. Its oxidizing properties are much stronger than oxygen. (Silicon dioxide is It can burn in fluorine gas and generate oxygen). Thermodynamically speaking, like the reaction between water and fluorine gas, silica can undergo a non-metallic (no reaction in solution) substitution reaction with fluorine gas. The chemical formula of this reaction is as follows:

2F ₂ ↑+SiO ₂ ＝＝＝＝＝SiF ₄ ↑+O ₂ ↑ (2)

The condition for the above reaction is T2, which is the second temperature.

Since the second component group 32 is a process reaction zone, the thickness of the silicon dioxide film generated on the working surface of the second component group 32 is much greater than the thickness of the silicon dioxide film generated on the working surface of the first component group 32. Therefore, a more active component is used. Fluorine gas for cleaning.

In an exemplary embodiment of the present disclosure, step S4 may include: passing pure fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group 32 .

In one embodiment, after determining the flow rate of fluorine gas, such as the maximum flow rate, fluorine gas can be introduced into the furnace tube for a second preset time period. In the same manner as step S2, the second thickness of the silicon dioxide film generated on the working surface of the second component group 32 can be measured first, and then the second preset time period is determined based on the second thickness and the flow rate of the fluorine gas, such as the maximum flow rate. The second thickness can be measured by an elemental analyzer; or the second thickness can be determined based on parameters of the previous process conditions. The specific measurement method for measuring the second thickness of the aforementioned silicon dioxide film is well known to those skilled in the art and will not be described in detail here.

By pre-measuring the second thickness of the silicon dioxide film on the working surface of the second component group 32 and setting the duration of pure fluorine gas to the second preset duration, the control process can be simplified and the cleaning efficiency can be improved.

The reason why fluorine gas (F ₂ ) is used to clean the second component group 32 instead of using hydrogen fluoride gas (HF) to clean the second component group 32 is because after the product SiO ₂ film is formed on the surface of the quartz 41, Surface stress occurs during the heating and cooling process, causing cracks on the quartz surface. Since the selectivity ratio of the F ₂ gas reaction is 1:4, that is, if one unit of the product SiO ₂ film is etched away, four units of furnace tube quartz will be consumed accordingly; while the selectivity ratio of the HF gas reaction is 1:1, That is to say, if one unit of the product SiO ₂ film is etched away, one unit of furnace tube quartz will be consumed accordingly. The reaction between HF gas and quartz is not as violent as the F ₂ reaction, and the selectivity ratio is different. The cracks generated on the quartz surface cannot be quickly consumed. Therefore, fluorine gas (F ₂ ) needs to be used to clean the second component group 32.

Referring to FIG. 4 , before cleaning the second component group 32 , the working surface surface of the second component group 32 includes working surface quartz 41 and a silicon dioxide film 42 generated on the working surface surface of the second component group 32 .

During the cleaning process, the silicon dioxide film 42 generated on the working surface surface of the second component group 32 will generate surface stress during the temperature rising and cooling process, causing cracks 43 to occur on the quartz surface (ie, the working surface quartz 41 ).

If hydrogen fluoride gas is used for cleaning, or the second preset time period is only set based on the second thickness of the silicon dioxide film generated on the working surface of the second component group 32, cracks 43 will still exist on the surface of the quartz 41 after the cleaning is completed. That is situation A.

The best cleaning effect should be that after the cleaning is completed, the cracks 43 on the surface of the quartz 41 are also cleaned, that is, situation B.

Therefore, during the process of introducing fluorine gas, since quartz (SiO ₂ ) is also silicon dioxide, the active fluorine gas will react with the silicon dioxide film 42 generated on the surface of the working surface of the second component group 32 and affect the quartz. The cracks 43 on the surface of 41 are cleaned. By flexibly controlling the duration and flow rate of the fluorine gas, the fluorine gas can be controlled to react with all the cracks 43 on the surface of the quartz 41 without leaving any cracks 43 after the cleaning is completed.

In an exemplary embodiment of the present disclosure, after the fluorine gas is introduced into the furnace tube and before the end of step S4, the method further includes: introducing diluted fluorine gas into the furnace tube when a preset condition occurs.

In one embodiment, the diluted fluorine gas includes inert gas and fluorine gas, and the inert gas includes nitrogen and/or inert gas. For cost reasons, the inactive gas may be nitrogen.

In one embodiment, in the diluted fluorine gas, the volume ratio of the inert gas and the fluorine gas is 1: (1-5). In a preferred embodiment, in the diluted fluorine gas, the volume ratio of the inert gas and the fluorine gas is 1:1.

Since the F ₂ gas reacts violently with quartz, in order to prevent the F ₂ gas from over-etching the crack-free quartz 41 , an inactive gas such as N ₂ gas can be introduced to dilute the F ₂ when a preset condition occurs.

In one embodiment, the preset condition may include that the temperature increase rate of the second component group 32 reaches a preset value.

Referring to Figure 5, in one embodiment, step S4 may include:

Step S41, monitor the temperature of the second component group;

Step S42, when the temperature rise rate of the second component group reaches the first preset rate, introduce diluted fluorine gas into the furnace tube;

Step S43: When the temperature rise rate of the second component group drops to the second preset rate, stop feeding the diluted fluorine gas.

Wherein, in one embodiment, the first preset rate is, for example, 8-10°C/min.

Wherein, in one embodiment, the second preset rate is, for example, 0-1°C/min.

In the embodiment shown in FIG. 5 , fluorine gas can be introduced first, and the temperature of the second component group 32 can be detected. When the temperature rise in the high-temperature area (second component group 42) is detected, it can be determined that the F2 gas reacts with the crack 43 to cause severe heat release, and the temperature of the second component group 32 is monitored at any time. When the temperature rise rate is greater than the Switch the mixed gas (i.e. diluted fluorine gas) immediately at a preset rate. When the temperature rise rate drops to the second preset rate, observe the temperature change at all times. When the temperature change is small or constant and no longer changes, Stop supplying diluted fluorine gas.

It should be noted that during the process of introducing _F2 into the furnace tube, since _F2 will not react with the first component group including the vacuum pipe and flange, all chemical reactions will occur in the high-temperature area (that is, including the quartz tube). and the second component group of the quartz boat) for reaction.

At the same time, it should be noted that because the temperature and pressure in the furnace tube are controllable, and the flow rate of fluorine gas or diluted fluorine gas per minute is controllable, the conditions for controllable reaction time and simple reaction process are met. High etching precision.

Through the embodiment shown in FIG. 5 , the residual cracks 43 on the surface of quartz 41 caused during the cleaning process can be effectively reduced, thereby solving the problem of excessively high particles and insufficient smoothness on the surface of quartz 41 in related cleaning technologies.

In step S5, inert gas is introduced into the furnace tube and vacuumed.

Figure 6 is a sub-flow chart of step S5 in one embodiment of the present disclosure.

Referring to Figure 6, in one embodiment, after step S4 ends and the flow of fluorine gas is stopped (including stopping the flow of diluted fluorine gas), step S5 may include:

Step S51: Inject inert gas into the furnace tube for a preset period of time and then evacuate.

Step S52, detect the gas in the furnace tube.

Step S53, determine whether the gas in the furnace tube contains fluorine ions. If so, return to step S51 to repeatedly pass in the inert gas for a preset time and then evacuate; if not, go to step S54 to stop the inert gas and vacuuming operations.

In the embodiment shown in Figure 6, inert gas such as _N2 can first be introduced to purge the quartz boat and quartz tube, and then vacuumed, and the gas in the furnace tube can be detected to see whether there are F ions. After there are no F ions in the gas in the furnace tube, the gas flow is stopped.

The embodiment shown in Figure 6 can prevent residual acid gas from continuing to etch quartz.

To sum up, compared with the prior art, the embodiments of the present disclosure have at least the following advantages:

1. Wet cleaning must remove all quartz products such as quartz tubes (Tubes), quartz boats (Boats), and quartz plates (Plates) in the chamber, which is technically difficult and can easily damage the furnace tubes. However, the dry cleaning method provided by the embodiment of the present disclosure The traditional cleaning method is performed by running the process program, and there are no safety hazards and technical difficulties.

2. Since there is no need to disassemble the quartz for wet cleaning, there is no need to equip related quartz cleaning equipment (such as quartz cleaning machine), which can reduce the budget, reduce the acid discharge pressure at the factory end, and reduce the manufacturing cost of integrated circuits.

3. Since there is no need to disassemble the quartz, human errors can be avoided and equipment losses can be reduced.

4. Since the temperature and pressure in the quartz tube (i.e., the second component group 32) are controllable, and the flow rate of the gas introduced per minute is controllable, the reaction time is controllable, the reaction process is simple, and the etching precision is high.

5. The dry cleaning method provided by the embodiment of the present disclosure only etches the working surface and does not destroy the sealing property of the quartz surface. During use of the cleaned furnace tube, the vacuum caused by excessive etching of the quartz sealing surface will not occur. Abnormalities cause product scrapping, further reducing the manufacturing cost of integrated circuits.

6. More than 90% of the problems of the furnace tube machine are related to excessively high particles in the chamber (that is, too many cracks 43 on the surface of the quartz 41). The dry cleaning method provided by the embodiment of the present disclosure can be used without disassembling the quartz parts. It can effectively improve the environment in the chamber and fundamentally solve most problems caused by excessive particle size.

7. The annual equipment maintenance time in wet cleaning is about 480H, while the dry cleaning method only takes 220H, which improves the manufacturing efficiency of integrated circuits and reduces the manufacturing cost of integrated circuits.

8. Using wet cleaning, the service life of the furnace tube is less than 1 year, while using dry cleaning method, the service life of the furnace tube can reach more than 2 years, reducing the manufacturing cost of integrated circuits.

Therefore, the dry cleaning method provided by the embodiments of the present disclosure can effectively improve the operating efficiency of the furnace tube.

Other embodiments of the disclosure will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the disclosure that follow the general principles of the disclosure and include common common sense or customary technical means in the technical field that are not disclosed in the disclosure. . It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Industrial applicability

Claims

A process equipment cleaning method for cleaning furnace tubes used in a diffusion process. The working surface of the furnace tube includes a silicon dioxide film generated in the diffusion process. The method includes:

heating a first assembly of the furnace tubes to a first temperature, the first assembly including a vacuum tube and a flange;

Passing hydrogen fluoride gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the first component group;

heating a second component group of the furnace tube, the second component group including a quartz tube and a quartz boat, to a second temperature, the second temperature being higher than the first temperature;

Pass fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface surface of the second component group;

Pour inert gas into the furnace tube and evacuate it.
The method of claim 1, wherein said passing fluorine gas into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group includes:

Pure fluorine gas is passed into the furnace tube to remove the silicon dioxide film generated on the working surface of the second component group.
The method according to claim 1 or 2, wherein after passing fluorine gas into the furnace tube and before passing inert gas into the furnace tube, it further includes:

When preset conditions occur, diluted fluorine gas is passed into the furnace tube.
The method of claim 3, wherein said introducing diluted fluorine gas into the furnace tube when a preset condition occurs includes:

Monitor the temperature of the second component group, and when the temperature rise rate of the second component group reaches a first preset rate, pass diluted fluorine gas into the furnace tube;

When the temperature rise rate of the second component group drops to the second preset rate, the flow of diluted fluorine gas is stopped.
The method of claim 4, wherein the first preset rate is 8-10°C/min; and/or the second preset rate is 0-1°C/min.
The method according to any one of claims 3 to 5, wherein the diluted fluorine gas includes inert gas and fluorine gas, and the inert gas includes nitrogen and/or inert gas.
The method according to claim 6, wherein the volume ratio of the inert gas and the fluorine gas in the diluted fluorine gas is 1: (1-5).
The method according to any one of claims 1 to 7, wherein said introducing hydrogen fluoride gas into the furnace tube includes: introducing hydrogen fluoride gas into the furnace tube for a first preset time period;

The introducing fluorine gas into the furnace tube includes: introducing fluorine gas into the furnace tube for a second preset time period.
The method of claim 8, further comprising:

Determining a first thickness of the silicon dioxide film generated on the working surface of the first component group and a second thickness of the silicon dioxide film generated on the working surface of the second component group;

The first preset duration is determined according to the first thickness, and the second preset duration is determined according to the second thickness.
The method of claim 9, wherein said determining a first thickness of a silica film formed on a working surface of said first component group and a first thickness of silica film formed on a working surface of said second component group The second thickness of the membrane includes:

The first thickness and the second thickness are measured by an elemental analyzer; or the first thickness and the second thickness are determined according to parameters of a previous process condition.
The method according to any one of claims 1 to 10, wherein said introducing hydrogen fluoride gas into the furnace tube includes:

The thickness of the silicon dioxide film generated on the working surface of the first component group is monitored, and when the thickness of the silicon dioxide film on the working surface of the first component group is less than a preset thickness, the flow of hydrogen fluoride gas is stopped.
The method of claim 11, wherein the preset thickness is 0-5 μm.
The method of any one of claims 1-12, wherein said heating the second assembly of furnace tubes to a second temperature includes:

After stopping the flow of hydrogen fluoride gas, start heating the second component group;

Alternatively, the heating of the second component group is started before the flow of hydrogen fluoride gas is stopped, and the temperature of the second component group is lower than the temperature of the first component group when the flow of hydrogen fluoride gas is stopped.
The method according to any one of claims 1 to 13, wherein said introducing inert gas into the furnace tube and vacuuming includes:

After stopping the flow of fluorine gas, flow inert gas into the furnace tube and evacuate, and detect the gas in the furnace tube to determine whether it contains fluorine ions;

When it is detected that fluoride ions are contained, the inactive gas is repeatedly introduced and vacuumed, and the gas in the furnace tube is repeatedly detected until no fluoride ions are detected;

Stop the inert gas flow and vacuuming operation.
The method according to any one of claims 1 to 14, wherein the first temperature is not less than 40°C and not greater than 100°C; and/or the second temperature is not less than 200°C.
The method of claim 15, wherein the first temperature ranges from 75°C to 100°C; and/or the second temperature ranges from 400°C to 500°C.