JPH04210236A - Treating agent for dry etching exhaust gas - Google Patents

Abstract

PURPOSE:To obtain a treating agent for catching harmful gas component in a dry etching exhaust gas by carrying on alkali metal aluminate or a tetraalkyl ammonium salt on active carbon. CONSTITUTION:Active carbon is immersed in the aqueous solution of an alkali metal aluminate or a tetraalkyl ammonium salt, or sprayed with the same aqueous solution to carry the alkali metal aluminate or the tetraalkyl ammonium salt on the active carbon. Thereafter, it is dried at a temp. not causing decomposition of these salts in an atmosphere of inert gas or in vacuum. Thus, obtained treating agent removes selectively harmful gas components in a dry etching exhaust gas produced at a time when a semiconductor is manufactured.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention is a semiconductor S! The present invention relates to a dry etching exhaust gas treatment agent that selectively removes and renders harmful gas components discharged from dry etching equipment in, for example, the ia process. [00021] More specifically, in dry etching, a gas selected from the group consisting of fluorocarbon gas, sulfur hexafluoride, hydrogen halide, boron halide, silicon halide, nitrogen trifluoride, chlorine, fluorine, bromine, etc. was done,
One or more reactive gases and one or more gases selected from oxygen, hydrogen, nitrogen, air, argon, helium, etc. depending on the purpose are added to the reactive gas to etch the material to be processed. The used gas is exhausted from the device as waste gas. The present invention relates to a processing agent used for selectively removing the reactive gas contained in the dry etching exhaust gas and harmful gas components generated during etching to render the dry etching exhaust gas harmless. [0003] [0003] In the semiconductor industry, 1. With the increasing integration of C, miniaturization has progressed rapidly, and the etching technology essential for forming finely patterned patterns has changed from wet etching to dry etching methods such as plasma etching and reactive ion etching, which have the advantages of selectivity and controllability. Almost migrated. [0004] Materials to be subjected to dry etching include silicon, polysilicon, silicon dioxide, silicon nitride, aluminum, aluminum-copper, aluminum-silicon, molybdenum, tungsten, titanium, titanium-tungsten, chromium, chromium oxide, arsenic- There are gallium etc. In addition, as reactive gases for dry etching, fluorocarbon gases such as tetrafluoromethane, hexafluoroethane, octafluoropropane, trifluoromethane, and dichlorotrifluoroethane, sulfur hexafluoride, boron trichloride, silicon tetrachloride, Silicon tetrafluoride, nitrogen trifluoride, hydrogen bromide, fluorine, chlorine, bromine, etc. are used.
In these methods, one or more gases selected from oxygen, hydrogen, nitrogen, air, argon, helium, etc. are added to the reactive gas, either singly or in combination depending on the purpose, to etch the material to be processed. are doing. This etching exhaust gas includes hydrogen fluoride, hydrogen chloride, hydrogen bromide, silicon tetrafluoride, sulfur tetrafluoride, carboxyl chloride, carboxyl fluoride, silicon tetrachloride, Salt boron, chlorine, fluorine,
It contains acidic and oxidizing harmful gas components such as bromine and ozone, and these harmful gas components must be treated to render them harmless from the viewpoints of environmental pollution, safety and hygiene, process pollution, corrosion, and the like. [0005] As this dry etching exhaust gas treatment method, wet and dry treatment methods are known, but in the wet method, an alkaline aqueous solution such as caustic soda or soda carbonate is used as the treatment agent, and the exhaust gas is washed with the treatment agent. Therefore, a common method is to absorb harmful gas components and render them harmless. However, the wet method requires complex equipment and high equipment costs, and because it is an aqueous solution, the processing agent, such as sodium, flows back into the etching equipment, and the solid content generated by the reaction between the processing agent and harmful gas components in the exhaust gas. There are problems such as device blockage. The dry processing method was proposed as a method to improve the problems of the wet method (Japanese Patent Application Laid-Open No. 1220-1989).
No. 25, JP-A No. 61-35849), but the treatment agent used in this method, in which halides of alkali metals and alkaline earth metals are supported on activated carbon, eliminates harmful substances in exhaust gas. The ability to process gas components is low,
The problem is that the processing agent filled in the processing tower must be frequently replaced, and the amount of processing agent used is large. Furthermore, depending on the harmful gas components in the exhaust gas, the treatment capacity is extremely low, and the types of harmful gas treatment components are limited. [0006]

[Problems to be Solved by the Invention] In order to solve the problems of the above-mentioned wet and dry etching methods, the present invention uses a dry processing method to treat harmful gas components discharged from a dry etching apparatus, thereby rendering the dry etching exhaust gas harmless. It is a treatment agent used for dry etching, which enables the treatment of multiple components of the acidic and oxidizing gases that are harmful gas components contained in the dry etching exhaust gas.It has a high treatment capacity and can be filled into an exhaust gas treatment tower to treat the exhaust gas The purpose of the present invention is to provide an excellent processing agent that requires less replacement of the processing agent and can withstand fluctuations in the concentration of the gas to be treated and the flow rate of the exhaust gas. [0007]

[Means for Solving the Problems] The present invention is a processing agent comprising activated carbon supported with one selected from alkali metal salts and tetraalkylammonium salts of aluminic acid, which may be used in a fluidized bed or a moving bed. Generally, a fixed bed is used, a treatment tower is filled with a treatment agent, and the exhaust gas from the dry etching equipment is passed through the treatment tower, and the treatment agent and the exhaust gas are brought into contact with each other, thereby eliminating multiple harmful substances contained in the dry etching exhaust gas. For example, in the case of a harmful gas component such as hydrogen chloride, it is reacted with sodium aluminate supported on activated carbon and treated with Na AI Cl.
4. By supplementing the treatment agent with
Alternatively, the processing ability is higher than that of a processing agent carrying chloride. [0008] The treatment agent of the present invention is prepared by immersing activated carbon in an aqueous solution selected from alkali metal salts and tetraalkylammonium salts of aluminic acid, or by spraying this aqueous solution onto activated carbon and stirring, and then treating the aluminic acid supported on activated carbon. at a high temperature at which the alkali metal and/or tetraalkylammonium salts of
In the case of alkali metal salts), dry at a temperature of 50 to 60°C (in the case of tetraalkylammonium salts) in an atmosphere of an inert gas such as nitrogen, argon, helium, etc. or in vacuum to remove adhering water, bound water, etc. It can be manufactured by a method of removing. [0009] If the processing agent contains water, it will react with reactive gases such as silicon tetrachloride and boron trichloride contained in the dry etching exhaust gas to produce products such as silicon dioxide and boric acid, which will cause the processing to deteriorate. If the tower is clogged, it may cause a decrease in processing capacity due to pore clogging of the processing agent, so the processing agent supported on the alkali metal salt and/or tetraalkylammonium salt of aluminic acid should contain substantially no water. Avoid including it. For this purpose, it is best to dry under a gas atmosphere as described above or in a vacuum. [00101 The activated carbon of the present invention has a specific surface area (N2
BET method) is 100-2500m27g, preferably 1
100-2000 m2/g is optimally used. If the specific surface area is too small, the ability to treat harmful gas components in exhaust gas will be low, and if the specific surface area is too large, the mechanical strength of the processing agent will decrease and it will deteriorate during handling and use, which is not preferable. Furthermore, the type of activated carbon is not particularly limited, such as coal-based, coconut shell-based, charcoal-based, etc. The shape of activated carbon is not particularly limited as long as it is granular, such as spherical or crushed. The particle size of activated carbon varies depending on the conditions of use, the size of the treatment tower, the treatment method such as moving bed or fluidized bed, and the difference in gas flow rate, but it is generally 0. 5-20mm, preferably 0
5 to 10 mm is appropriate. [0011] Examples of the alkali metal salt and/or tetraalkylammonium salt of aluminate include lithium aluminate, potassium aluminate, sodium aluminate, cesium aluminate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetramethylammonium carbonate. , tetraethylammonium carbonate, tetramethylammonium chloride, tetraethylammonium chloride, tetramethylammonium aluminate, tetramethylammonium aluminate, etc.
Among these, sodium aluminate, potassium aluminate, tetramethylammonium hydroxide, tetramethylammonium carbonate, tetramethylammonium chloride, tetramethylammonium aluminate, etc. are preferred, but sodium aluminate and carbonate are generally preferred. Tetramethylammonium is optimally used. Tetramethylammonium carbonate and Tetramethylammonium aluminate can be produced by reacting tetramethylammonium hydroxide with carbon dioxide gas and aluminum hydroxide, respectively. [0012] If the amount of alkali metal salt and/or tetraalkylammonium salt of aluminic acid supported on activated carbon is too small, there will be no supporting effect, and if it is too large, pores of the activated carbon will be clogged, and instead, exhaust gas 1 to 20w, as the ability to process harmful gas components inside is low.
% (supported amount in grams per 100 ml of activated carbon), preferably 5 to 15 W/'V%. [0013]

[Action] When using the treatment agent of the present invention, it is not clear what kind of action the alkali metal salt and/or tetraalkylammonium salt of aluminic acid has, but activated carbon, alkali metals, and alkaline earth metals Compared to the case where halides and/or hydroxides supported on activated carbon are used as a treatment agent, it is possible to treat multiple harmful gas components contained in dry etching exhaust gas, and the treatment capacity is also higher. . This is difficult to believe only from the reaction of alkali metal salts and/or tetraalkylammonium salts of aluminic acid with harmful gas components and adsorption ability to activated carbon. It acts as a kind of catalyst and increases the adsorption capacity of activated carbon, but it is presumed that this is due to their interaction. [0014]

[Example] [Example 1] 100 ml of granular activated carbon (specific surface area: 1200 m2/g, particle size: 0.5-2 mm) was immersed in 40 ml of a 25% aqueous solution of sodium aluminate, stirred, and then heated with dry nitrogen gas for 200 mL.
℃ for 3 hours, water-free sodium aluminate supported activated carbon (N a A l 02 supported amount
A treatment agent (100ml activated carbon) was prepared. [0015] Fill a Teflon processing cylinder with a perforated plate with 50 ml of processing agent (filling height 300 mm) L, and use SF6 as a dry etching gas from the bottom at 125 Nml/min.
, C2C14F4 25Nml/min, C2
C13F5 25Nml/min, 02 2 ONm
Discharge was carried out under reduced pressure while supplying 1/min, and the exhaust gas that etched the polysilicon was circulated. This dry etching exhaust gas contains SF4°SOF2,
F2, HF, S iF4. HCI, COF2. The sample contained harmful gas components such as 03, Sic 14, and CI2, but as a result of exhaust gas measurement at the outlet side of the upper part of the processing cylinder, all of the harmful gas components were 1 ppm or less. [0016] [Example 21 The treatment agent (KA
102 supported amount 10g/100ml activated carbon) was prepared,
The same dry etching exhaust gas as in Example 1 was circulated in the same manner. As a result, as in Example 1, all harmful gas components were 1 ppm or less. [0017] [Example 3] Using tetramethylammonium hydroxide instead of sodium aluminate in Example 1, 50
The processing agent ((CH3)4 NOH supported amount 10g/100ml
Activated carbon] was adjusted, and the same dry etching exhaust gas as in Example 1 was circulated in the same manner. As a result, as in Example 1, all harmful gas components were 1 ppm or less. [0018] [Example 4] Tetraethylammonium hydroxide was used instead of sodium aluminate in Example 1, and the mixture was heated at 50°C with dry nitrogen gas.
The processing agent [(C2H5) 4 NOH supported amount 10 g/100
ml activated carbon] was prepared, and the same dry etching exhaust gas as in Example 1 was passed through it in the same manner. Results Example 1
Similarly, harmful gas components were all below 1 ppm. [0019] [Example 5] A treatment agent was prepared in the same manner as in Example 1, except that tetraethylammonium chloride was used in place of the sodium aluminate in Example 1, and it was dried at 50° C. for 5 hours with dry nitrogen gas. C(C2H5) 4 NCI supported amount 10g/100m1
Activated carbon] was prepared, and the same dry etching exhaust gas as in Example 1 was passed in the same manner. As a result, as in Example 1, the harmful gas components were all below 1 ppIi1. [00201[Example 61 Tetramethylammonium aluminate [aluminum hydroxide (A I
(OH) 3 8. 5g) of tetramethylammonium hydroxide [(CH3)2N08 25% aqueous solution 40ml
) using dry nitrogen gas,
The processing agent [(CH3) 4 NA 102 supported amount Log/1 was prepared in the same manner as in Example 1 except that it was dried at 0°C for 5 hours.
00g activated carbon] was prepared, and the same dry etching exhaust gas as in Example 1 was passed through the same process. As a result, as in Example 1, all harmful gas components were 1 ppm or less. [00211 [Example 71 Instead of sodium aluminate in Example 1, tetramethylammonium carbonate (prepared by reacting carbon dioxide gas with tetramethylammonium hydroxide) was used and dried at 50°C for 5 hours with dry nitrogen gas. Other than that, the treatment agent CC(CH4) 4 N] 2 CO3 supported amount was 1 by the same operation as in Example 1.
0g/100ml activated carbon] was prepared, and the same dry etching exhaust gas as in Example 1 was passed through the same operation. As a result, as in Example 1, all harmful gas components were 1 ppm or less. [0022] [Example 81 Treatment agent similar to Example 1 (N a A 102 supported) 5
Fill 0ml into a Teflon processing cylinder with a perforated plate (filling height 3001m) L, as dry etching gas from the bottom, HBr35Nml/min, SiF425N
ml/min, CI2 1ON ml/mi
While supplying n, discharge was carried out under reduced pressure, and the exhaust gas in which polydinocon was etched was circulated. The exhaust gas of this dry etching includes HBr, Br, 5iBr1
．． It contained harmful gas components such as SiF4, but as a result of exhaust gas measurement at the outlet side of the upper part of the processing cylinder, the harmful gas components were
All were below 1 ppm. [0023] [Example 91 Using the same treatment agent [(C2H5) NCl supported amount as in Example 5], the same dry etching exhaust gas as in Example 8 was passed through in the same manner. As a result, as in Example 8, all harmful gas components were less than 1 ppm. [0024] [Example 10] Treatment agent C ((CH3) 4 N) 2 similar to Example 7
A dry etching exhaust gas similar to that in Example 8 was circulated in the same manner as in Example 8, with the amount of CO3O3 supported. As a result, as in Example 8, all harmful gas components were 1 ppm or less. [0025] [Example 11] 50 ml of the same processing agent as in Example 2 (carrying KA102) was filled into a Teflon processing cylinder with a perforated plate (filling height: 300 m).
m) and CF41 as a dry etching gas from the bottom.
5ONml/min, Hz 2ONml/min
While supplying 5 iOz of etched exhaust gas, discharge was carried out under reduced pressure. The exhaust gas of this dry etching includes HF, F2, SiF4.
It contained harmful gas components such as COF2 and 03, but as a result of measuring the exhaust gas at the outlet side of the upper part of the processing cylinder, the harmful gas components were all 1 ppm or less. [0026] [Example 12] The same treatment agent ((CH3)4 NOHOH supported amount) as in Example 3 was used, and the same dry etching exhaust gas as in Example 11 was circulated in the same operation. As a result, the same as in Example 11 was obtained. All harmful gas components were 1 ppm or less. [0027] [Example 13] 50 ml of the same treatment agent as in Example 6 [(CH3)4NAlO2 supported) was filled into a Teflon treatment tube with a perforated plate (
Filling height 300mm) L, dry etching gas from the bottom, CF4 150 Nml/min and 02 20
Discharge was carried out under reduced pressure while supplying Nml/min, and the exhaust gas that etched Si3N4 was circulated. This dry etching exhaust gas contains HF, F2
, contained harmful gas components such as SiF4,
As a result of measuring the exhaust gas at the outlet side of the upper part of the processing cylinder, all of the harmful gas components were 1 ppm or less. [0028] [Example 141 Treatment agent similar to Example 7 [((CH3)4N)2C
The same dry etching exhaust gas as in Example 13 was circulated using the same operation as in Example 13, using the same amount of O3O3 supported. Results Example 1
Similar to No. 3, the harmful gas components were all below 1 ppm. [0029] [Example 151 50 ml of the same treatment agent as in Example 1 (supporting NaAIO2)
Fill the Teflon processing tube with perforated plate (filling height 300
mm) From the bottom as a dry etching gas, BC
I+ 15 ONml/min, CHF3 3
ONml/min, C1,! 25 Nml/min
While supplying the gas, discharge was carried out under reduced pressure, and the exhaust gas in which A1 was etched was circulated. The exhaust gas of this dry etching contains BCl3. HF HCl,,C1,!
However, as a result of exhaust gas measurement at the outlet side of the upper part of the processing cylinder, all of the above harmful gas components were 1.
It was less than ppm. [00301 [Example 16] Treatment agent similar to Example 5 [(C2HB) NCl supported]
The same dry etching exhaust gas as in Example 15 was circulated using the same operation. As a result, as in Example 15, all harmful gas components were 1 ppm or less. [00311[Example 171 50 ml of the same treatment agent as in Example 1 (supporting NaAl○2)
Fill the Teflon processing tube with perforated plate (filling height 300
mm) HCl and S'rF4. as harmful gas components contained in the dry etching exhaust gas from the lower part of L.
SF4, BC13, HBr, and C12 were each diluted with nitrogen gas to prepare a model dry etching exhaust gas with a concentration of 1vol%, and each model gas was passed through at a flow rate of 0.3Nl/min. The harmful gases in each model exhaust gas were measured at the exit side of the upper part of the processing cylinder (1 pan detection was taken as the breakthrough point), and the processing agent capacity (the processing amount of harmful gas per 11 processing agents was expressed as the number of moles) I looked into it. The results were as shown in Table 1-■. [0032] [Example 18] Treatment agent C ((CH3) 4 N) 2 similar to Example 7
The ability of the treatment agent was investigated in the same manner as in Example 17 using the C○3 loading value. The results were as shown in Table 1-■. [0033] [Comparative Example 11 Granular activated carbon similar to Example 1 was heated to 200°C in dry nitrogen gas.
The ability of the processing agent was examined in the same manner as in Example 17 except that this was dried for 3 hours and used as the processing agent. The results were as shown in Table-1-0. [0034] [Comparative Example 2] A treatment agent ( Example 17
The ability of the treatment agent was examined using the same procedure as above. The results were as shown in Table 1-■. [0035] Comparative Example 31 A treatment agent was prepared in the same manner as in Example 1, except that anhydrous calcium chloride was used in place of the sodium aluminate in Example 1, and the treatment was dried at 200° C. for 3 hours with dry nitrogen gas. (Ca
A CL2 supported amount of 10 g/100 ml activated carbon) was prepared, and the ability of the treatment agent was examined in the same manner as in Example 17. The results were as shown in Table 1-■. [0036]

[Table 1] [0037]

[Effects of the Invention] As described above, when the treatment agent of the present invention is filled into a treatment tower and used for dry etching exhaust gas treatment, it not only solves the problems caused by wet treatment, but also improves the effectiveness of conventional dry etching treatment. Compared to processing agents used in the conventional method, it is possible to treat multiple harmful gas components, has a high processing capacity, and can withstand long-term use when compared per processing tower unit. Moreover, if a processing agent in which a tetraalkylammonium salt is supported on activated carbon is used, it does not contain alkali metals or alkaline earth metals, so there is no risk of contamination of the semiconductor manufacturing process, and safety and reliability can be improved.

Claims (2)

[Claims] 1. A treatment agent for dry etching exhaust gas, characterized in that activated carbon supports one selected from alkali metal salts and tetraalkylammonium salts of aluminic acid. 2. The treatment agent according to claim 1, wherein the tetraalkylammonium salt is one selected from hydroxides, carbonates, halides, and aluminates of tetraalkylammonium.