阅读说明：本技术 一种lpcvd炉管在线清洗方法 (Online cleaning method for LPCVD furnace tube ) 是由 梁笑 林佳继 刘群 张武 庞爱锁 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种一种LPCVD炉管在线清洗方法,包括以下步骤：将炉管炉门封闭,检查真空,确认机台真空度,然后升温；通入N2,升温至350-700℃稳定,然后停止通入氮气,同时控制系统压力处于100mtorr-1000mtorr的压力范围下；进气口通入无机非金属氟化物气体；关闭无机非金属氟化物气体进气阀门,同时通入氮气赶走未完全反应的前驱体以及反应生成物；通入氮气,回压,然后炉管降温；待炉管内压力接近大气压时,打开炉门清洗完成。本发明的在线清洗方法能够用于清洗LPCVD设备工艺过程中沉积在炉管内壁的非晶硅、氮化硅,二氧化硅等薄膜。操作简便,随时可以对反应管进行清洗处理,效果显著,灵活性强,能够有效克服湿法清洗的缺点。(The invention discloses an LPCVD furnace tube online cleaning method, which comprises the following steps: closing the furnace tube and the furnace door, checking vacuum, confirming the vacuum degree of the machine table, and then heating; introducing N2, heating to 350-700 ℃ for stabilization, then stopping introducing nitrogen, and simultaneously controlling the system pressure to be within the pressure range of 100-1000 mtorr; inorganic non-metal fluoride gas is introduced into the gas inlet; closing an inorganic non-metal fluoride gas inlet valve, and simultaneously introducing nitrogen to drive off incompletely reacted precursors and reaction products; introducing nitrogen, back-pressing, and then cooling the furnace tube; and opening the furnace door to complete cleaning when the pressure in the furnace tube is close to the atmospheric pressure. The online cleaning method can be used for cleaning amorphous silicon, silicon nitride, silicon dioxide and other films deposited on the inner wall of the furnace tube in the process of the LPCVD equipment. The method is simple and convenient to operate, can clean the reaction tube at any time, has an obvious effect and strong flexibility, and can effectively overcome the defect of wet cleaning.)

1. An LPCVD furnace tube on-line cleaning method is characterized by comprising the following steps:

step 1: closing the furnace tube and the furnace door, checking vacuum, confirming the vacuum degree of the machine table, and then heating;

step 2: introduction of N₂Heating to 350-700 ℃ for stabilization, then stopping introducing nitrogen, and simultaneously controlling the system pressure to be in a pressure range of 100-1000 mtorr;

and step 3: inorganic non-metal fluoride gas is introduced into the gas inlet;

and 4, step 4: closing an inorganic non-metal fluoride gas inlet valve, and simultaneously introducing nitrogen to drive off incompletely reacted precursors and reaction products;

and 5: introducing nitrogen, back-pressing, and then cooling the furnace tube;

step 6: and opening the furnace door to complete cleaning when the pressure in the furnace tube is close to the atmospheric pressure.

2. The on-line cleaning method for LPCVD furnace tube of claim 1, wherein in step 2, 1-50LN is introduced₂。

3. The on-line cleaning method for LPCVD furnace tube of claim 1, wherein in step 3, the inorganic non-metal fluoride gas is NF₃、CF₄，PF₅，SF₆。

4. The method as claimed in claim 1, wherein in step 3, the flow rate of the inorganic non-metallic fluoride gas is 10-10000 sccm.

5. The method as claimed in claim 1, wherein in step 4, 1-50L of nitrogen is introduced.

6. The method as claimed in claim 1, wherein in step 5, the furnace is cooled to 500 ℃.

7. The method as claimed in claim 1, wherein in step 5, 1-50L of nitrogen is introduced.

Technical Field

The invention particularly relates to an LPCVD furnace tube online cleaning method.

Background

LPCVD (low pressure chemical vapor deposition) is widely used in large scale integrated circuit and silicon charge coupled devices, CCD semiconductor optics and crystalline silicon solar cell fabrication. The deposited silicon nitride, amorphous silicon and silicon dioxide films are applied to the fields of integrated circuit insulation isolation, doping masking, passivation protection, crystalline silicon solar cell contact passivation and the like. The LPCVD passivation film has the following characteristics: the deposition temperature is low, the uniformity is good, the film components can be well controlled, and the step coverage, controllability and repeatability are good; low cost, high yield, suitability for mass production and the like.

When the thin film such as silicon nitride, amorphous silicon, etc. grows, these substances also grow on the inner wall of the LPCVD reaction furnace tube. Along with the increase of the number of the growing furnaces, the film on the inner wall of the reaction furnace is also thickened correspondingly. However, when the thickness of the film reaches a certain thickness, due to the difference of expansion coefficients between the film and the quartz, the film will peel off and the quartz tube will crack, which will seriously affect the quality of the process, the service life of the quartz tube and the mechanical pump. In the prior art, after a furnace tube grows for a certain number of furnaces, the reaction tube is unloaded from the furnace tube, and is etched by hydrofluoric acid or hydrofluoric acid plus nitric acid, and is washed and dried by a large amount of pure water. The wet etching cleaning method not only can generate a large amount of waste water, but also can cause long-time equipment shutdown and expensive material cost, and can cause low utilization rate of LPCVD machines and high operation cost.

Disclosure of Invention

In view of the above situation, the present invention provides an on-line cleaning method for LPCVD furnace tube to overcome the drawbacks of the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

an LPCVD furnace tube on-line cleaning method comprises the following steps:

step 1: closing the furnace tube and the furnace door, checking vacuum, confirming the vacuum degree of the machine table, and then heating;

step 2: introduction of N₂Heating to 350-700 ℃ for stabilization, then stopping introducing nitrogen, and simultaneously controlling the system pressure to be in a pressure range of 100-1000 mtorr;

and step 3: inorganic non-metal fluoride gas is introduced into the gas inlet;

and 4, step 4: closing an inorganic non-metal fluoride gas inlet valve, and simultaneously introducing nitrogen to drive off incompletely reacted precursors and reaction products;

and 5: introducing nitrogen, back-pressing, and then cooling the furnace tube;

step 6: and opening the furnace door to complete cleaning when the pressure in the furnace tube is close to the atmospheric pressure.

Further, in step 2, 1-50LN is introduced₂。

Further, in step 3, the inorganic non-metal fluoride gas is NF₃、CF₄，PF₅，SF₆And the like, these fluorides are decomposed into F at high temperature₂Fluorine gas (F)₂) Is a relatively active substance and has extremely strong reaction activity; can react with amorphous silicon, silicon nitride and silicon dioxide film to generate SiF₄(SiF₄Is a gaseous substance) and then pumped out by a pump, thereby cleaning the inner wall of the furnace tube from the deposited film. The reaction chemical formula is as follows:

2F₂+Si→SiF₄；

6F₂+Si₃N₄→3SiF₄+2N₂；

2F₂+SiO₂→SiF₄+O₂。

further, in the step 3, the flow rate of the inorganic non-metallic fluoride gas is 10-10000 sccm.

Further, in the step 3, the time for introducing the inorganic non-metal fluoride gas is 10-300 min, and the introducing time can be adjusted according to different film etching rates.

Further, in step 4, 1-50L of nitrogen gas is introduced.

Further, in step 5, the furnace tube is cooled to 500 ℃.

Further, in step 5, 1-50L of nitrogen is introduced, the temperature is kept for 1-30min, the pressure is returned, and then the temperature of the furnace tube is reduced to 500 ℃.

The invention has the beneficial effects that:

(1) the online cleaning method can be used for cleaning amorphous silicon, silicon nitride, silicon dioxide and other films deposited on the inner wall of the furnace tube in the process of the LPCVD equipment. The online cleaning method can be realized by only slightly improving the prior LPCVD system, the reaction tube does not need to be detached from the equipment, the operation is simple and convenient, the reaction tube can be cleaned at any time, the effect is obvious, the flexibility is strong, and the defect of wet cleaning can be effectively overcome.

(2) Compared with wet cleaning, the online cleaning method of the furnace tube avoids wet etching of the machine. The method has the advantages of simple and flexible operation and can be cleaned at any time without cooling the furnace tube or dismounting the furnace tube.

(3) The furnace tube online cleaning method of the invention adds inorganic non-metal fluoride gas, and adopts HF + HNO compared with wet etching₃More environmental protection and lower cost.

(4) The furnace tube online cleaning method can effectively improve the utilization rate of LPCVD machines and reduce the LPCVD operation cost.

Drawings

FIG. 1 is a schematic flow chart of the on-line cleaning method for LPCVD furnace tube according to the present invention.

FIG. 2 is a diagram illustrating the effect of the LPCVD furnace tube on-line cleaning according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Reference herein to "a plurality" means greater than or equal to two. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.

Example 1

As shown in fig. 1, an LPCVD furnace tube online cleaning method includes the following steps:

step 1: closing the furnace door, checking vacuum and confirming the vacuum degree of the machine; specifically, in the embodiment, the leak detection is carried out in vacuum, and the leak rate is less than 10 mtorr/min; then the temperature of the machine is raised;

step 2: after the leak detection is finished, keeping the 10LN to be introduced₂Heating to 500 ℃ for stabilization, then closing the nitrogen gas inlet valve, and simultaneously controlling the system pressure to be at 500 mtorr;

and step 3: introducing inorganic non-metal fluoride gas into a gas inlet, wherein the gas flow is 1000sccm, and the ventilation time is 150 min; the inorganic non-metallic fluoride gas may be NF₃、CF₄，PF₅，SF₆And the like, or two or more kinds thereof. In this example, the inorganic nonmetallic fluoride gas used was NF₃。

And 4, step 4: closing the air inlet valve, simultaneously introducing 30L of nitrogen, and removing incompletely reacted precursor and reaction product SiF by using a vacuum pump₄；

And 5: introducing 20L of nitrogen, keeping for 5min, back-pressing, and then cooling the furnace tube to 500 ℃;

step 6: and when the pressure in the furnace tube is close to the atmospheric pressure, opening the furnace door, and finishing cleaning.

As shown in FIG. 2, the cleaning method of the present invention has a better cleaning effect on the amorphous silicon deposited on the furnace tube, and the deposited amorphous silicon is significantly reduced and leaks out of the original quartz surface as the cleaning time increases.

Example 2

As shown in fig. 1, an LPCVD furnace tube online cleaning method includes the following steps:

step 1: closing the furnace door, checking vacuum and confirming the vacuum degree of the machine; specifically, in the embodiment, the leak detection is carried out in vacuum, and the leak rate is less than 10 mtorr/min; then the temperature of the machine is raised;

step 2: after the leak detection is finished, keeping the 50LN to be introduced₂Heating to 350 ℃ for stabilization, then closing the nitrogen gas inlet valve, and simultaneously controlling the system pressure to be in the pressure range of 800 mtorr;

and step 3: inorganic non-metal fluoride gas is introduced into the gas inlet, the gas flow is 10sccm, and the ventilation time is 300 min; in this example, the inorganic nonmetallic fluoride gas used was CF₄。

And 4, step 4: the inlet valve was closed and 50L of nitrogen was addedGas, using a vacuum pump to drive off incompletely reacted precursor and reaction product SiF₄；

And 5: introducing 30L of nitrogen, keeping for 10min, back-pressing, and then cooling the furnace tube to 500 ℃;

step 6: and opening the furnace door to complete cleaning when the pressure in the furnace tube is close to the atmospheric pressure.

Example 3

As shown in fig. 1, an LPCVD furnace tube online cleaning method includes the following steps:

step 1: closing the furnace door, checking vacuum and confirming the vacuum degree of the machine; specifically, in the embodiment, the leak detection is carried out in vacuum, and the leak rate is less than 10 mtorr/min; then the temperature of the machine is raised;

step 2: after the leak detection is finished, 25LN is kept introduced₂Heating to 400 ℃ and stabilizing, then closing a nitrogen gas inlet valve, and simultaneously controlling the system pressure to be in a pressure range of 700 mtorr;

and step 3: inorganic non-metal fluoride gas is introduced into the gas inlet, the gas flow is 6000sccm, and the ventilation time is about 100 min; in this example, the adopted inorganic nonmetallic fluoride gas is SF₆。

And 4, step 4: closing the air inlet valve, simultaneously introducing 35L of nitrogen, and removing incompletely reacted precursor and reaction product SiF by using a vacuum pump₄；

And 5: introducing 10L of nitrogen, keeping for 25min, back-pressing, and then cooling the furnace tube to 500 ℃;

step 6: and opening the furnace door to complete cleaning when the pressure in the furnace tube is close to the atmospheric pressure.

It should be understood by those skilled in the art that various features of the above-described embodiments can be combined in any combination, and for the sake of brevity, all possible combinations of features in the above-described embodiments are not described in detail, but rather, all combinations of features which are not inconsistent with each other should be construed as being within the scope of the present disclosure.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application.