DD200980B1 - METHOD AND APPARATUS FOR EXHAUST GASIFICATION IN PLASMACHEMICAL APPLICATION PROCESSES - Google Patents

Description

Field of application of the invention

The invention relates to a method for the detoxification of toxic fluorine- and chlorine-carbon-containing exhaust gases, as they arise in the structuring of Halbleitelementan by plasmachamischa etching processes and an apparatus for performing the method.

Characteristic of the known technical solutions

The creation of small structures in various materials, such as silicon, Sili2iumoxid. Silicon nitride or aluminum, in the production of Halblertar.bauelementen done on a large scale by plasma chemical etching processes.

Daoei are produced under the influence of a high-frequency discharge of fluorine- and / or chlorocarbon-reactive etching media.

The resulting reaction products contain a high proportion of toxic substances emitted to the environment via an exhaust system. The resulting concentrations may be well above the MIK values. According to the state of the art, no methods and devices for detoxification are known for the toxic exhaust gases occurring in plasma-chemical etching processes for structuring semiconductor components.

However, it is known to detoxify gas streams contaminated with toxic substances in cleaning towers with the aid of a suitable washing liquid. In fieinigungsturm the Waschflussigkeit and the gas stream is conducted in countercurrent.

The use of packing blocks makes the cleaning tower reach a large working surface and with a correspondingly long residence time of the gas, a high degree of conversion, i. achieved a great detoxification effect.

Since plasma-chemical etching processes take place in a vacuum, oil mist and the toxic waste gas escape from the recipient through the use of vacuum pumps. These oil mist would precipitate on the packing and reduce the reaction surface and thus reduce the degree of conversion.

Object of the invention

The aim of the invention is to avoid the pollution of the environment Mittoxischenfluor- and / or chlorcsrbcnhaIngen exhaust gases. Presentation of the veson of the invention

The task of the deferral is. to provide a method and apparatus which avoids the omission of the toxic fluorine and / or choricarbonium exhaust gases occurring in the olmatic chemical etch process for patterning semiconductor devices. According to the invention, the object is achieved in that the exiting from the recipient and separated from Olbastandteilen Abgasstem mitteis a Kaliumhydrcxidaerosois, d3S may be mixed with an alkanol in a suitable reaction vessel at atmospheric pressure and Raumtamperatur is detoxified. Be the detoxification reaction form soluble in Kaliumhydrcxidlosung salts and / or Athar

The device for exhaust gas decontamination in plasma chemical etching bssteht from a spaicherbehälter, which is connected to the etching system. Via a line provided with a reducing valve, the spa container is connected to the following oil separator. The oil separator is connected to a reaction vessel. The Verbindungslsttung from Olabscheider opens at the top of the reaction vessel. Starting from the foot of the Resktionsgefaßes a riser to etnam Vorratsbenälter, which is mounted above the Resktionsgefaßes and is connected to a vacuum pump attached. The Vorratsbehaltcr is üab sine Lauung with shut-off valve and throttling valve verbunaen with angeoroneten the head of the Resktionsgefaßes atomizer, at the foot of the reaction vessel a suction is attached. The device is in a suctionable Sehaitms.

The method is realized in the associated apparatus as described below.

The recipient of a plasma chemical etching system is pumped out by means of vacuum pumps, whereby Clnaoel suftreten in the exhaust gas, intermittently after each completed etching process- The exhaust gas is discharged into a, to the Änanlage anschl eßenden storage tank, with the help of the intermittent seizure of the exhaust gas is compensated

Thereafter, the exhaust gas discharged from its Ölbastandteilen is introduced at the head of the subsequently arranged Reaktlonsgefaßes, By a partition in the lower third of the reaction vessel is in a Resktionsraum and a Vorratsbehalter (lower third) divided Seiae spaces are through At the top of the reaction chamber is sprayed by means of a ZerstauDerduse and compressed air Kaltumhydroxidlbsung in the reaction chamber now enolgt the chemical reaction of the toxic constituents of the exhaust 'The potassium hydroxide aerosol, the detoxified exhaust gas and the reaction products of the detoxification process via the connecting pipe in the Reservoir filled with potassium hydroxide The detoxified waste gas collecting between the surface of the solution and the dividing wall is released to the environment via a suction line.

After closing the shut-off valve and switching off the vacuum pump, the atomization of the potassium hydroxide solution is continued. When the liquid level in the high tank drops to a certain level, it repeats pumping up the potassium hydroxide solution

The circulating potassium hydroxide solution with the reaction products dissolved therein is renewed cyclically.

The device for exhaust gas detoxification is arranged in a closed container by means of a vacuum pump at the joints of the device austreienden exhaust gases are sucked out of the container

With the solution according to the invention, it is possible to detoxify the exhaust gas which has abounded in the course of plasma-chemical etching processes in an intermittent manner and in the form of exhaust gas

In the case of plasma-chemical etching processes for structuring semiconductor components, the main etching metals used are, in particular, tetrachloromethane, tetrafluorminets and trimethyl methane

The exhaust gases which are pumped out of the containers in which the etching processes are discharged usually contain fluorine water peat, fluorophosgene and silicon tetrafiuide. In addition, the exhaust gases contain oil components which are caused by vacuum pumps used to pump out the containers

The intermittent Aagas is stored and subsequently separated from the contained Olbestandteilen

The subsequent detoxification is carried out at atmospheric pressure and room temperature by means of an aerosol, best from a 15% aqueous potassium hydroxide solution Here are the following reactions.

HF * KCH -> KFtHjO CD 5 t 4KOH -r 2KF 2HjO + K2CO3 SIFi-r-SKCH - * 4KF τ 3H2O + K2SiO3

During the aluminum structuring, HCl, CCCI2 and AICI3 are formed in the exhaust gas, which are detoxified by means of a 15% aqueous potassium hydroxide solution. The following reactions occur: HCL * KCH - * KCl + W20

COCL -r 4KCH - 2KCl - K2CC0 - ZH2O AICI3 -6K0H - * 3KCl-r K3Al (OH) b

If oxygen-free substrate is treated with toluene methane, then in addition to sodium dichloride and hydrogen fluoride there is also perfluorobutane in the exhaust gas.

The thus composed offgas is detoxified with an aerosol consisting of 15% potassium hydroxide solution and 20% methanol as follows:

S1F4 + 0KCH 4KF + K2S1O3 - 3H2O

HF - "- KOK KF + H2O CC; J C = CF2-CH3OH CF; j C-CFj-C-CH, CF, CF, 1,1, trifluoro2-tnfluoromethyl-3,3-difluoropropyl-methyl ether

The salts formed in the detoxification reactions are soluble in the potassium hydroxide solution

The apparatus for exhaust gas detoxification in plasma chemical etching processes will be explained in more detail below with reference to its practice

The accompanying drawing shows a device for detoxification of the toxic exhaust gases occurring in olymachemic At2 processes for Stri ktunenjng of semiconductor devices.

After the plasma-chemical etching process has ended, the recipient of the etching system is emptied by means of vacuum pumps. The toxic waste gases which are formed discontinuously are introduced into a storage container 1 together with the dusts which cause the use of vacuum pumps. Through the Speicherbehalter 1, at the soot is 2U Peinigungszwecken a screw plug 13, a jerky Beiastung of Reakt on, gefaßes 4 vermeder In the line that connects the Speicherbhalter 1 with the subsequently arranged Olabschaider 3, there is a reducing valve 2 Mit After passing through the oil separator 3, the exhaust gas at the head of the Reaktlonsgefaßes 4 enters the reaction chamber 5 sin The Reaknonsgsfaß 4 is through a partition 10, which is located in the outer third of Reaktionsgstaßes 4 , divided into a reaction space 5 and a Vorratsbhalter 11.

Mid-compressed air and a spray nozzle 6, which st arranged at the top of Reaktlonsgefaßes 4, m is formed in the reaction chamber 5, an aerosol of potassium hydroxide solution

The potassium hydroxide solution fed to the atomizing nozzle 6 is introduced via a throttle valve 3 into the supply line.

In the reaction chamber 5, salts soluble in potassium hydroxide are formed from the toxic constituents of the exhaust gas by the above-described chemical reactions ether and / caer via a connecting pipe 9, which connects the reaction space 5 to the storage vessel 11 and centrically n the '' 'raceway attached Aerosol, detoxified waste gas, and the reaction products into the pre-reservoir 11. The connecting tube Tanks into the potassium hydroxide solution. Between the partition wall 10 and the surface of the potassium hydroxide solution contained in the reservoir 11, the detoxified exhaust gas collects and is discharged via the suction line 12.

The potassium hydroxide solution used for detoxification is recirculated. For this purpose, a vacuum is created in certain by the level of the elevated tank 7 cycles by closing the shut-off valve 14 by means of a connected via a suction line 13 water jet pump, whereby the potassium hydroxide solution from the reservoir 11 via the riser 15 in the elevated tank? arrives. After opening the shut-off valve 14 and turning off the water-jet pump, the tnt-poisoning process is discontinued as described above.

The potassium hydroxide solution is removed after several detoxification cycles via the drain valve 15 and the drain line 19 from the reservoir 11. Subsequently, potassium hydroxide solution is introduced into the primary reservoir 11 via the filler neck 17.

The device for Abgesentgiftung in plasmachemischen etching processes is arranged in a suctionable container.

The exiting at joints of the device exhaust gases are sucked by a vacuum pump, so that no load can occur the working space with the toxic exhaust.

Claims (7)

-1 - 234 аиь ι Invention claim: 1. A method for exhaust gas purification bai plasmachemiscnen etching processes, characterized aaß the exhaust gas is stored after leaving the Reziptentan, aaß it is then separated from contained Olbestandteilen and that as thereafter with an alkaline aerosol, in particular from a 5- to 40% potassium hydroxide solution , is detoxified. 2. The method according to item 1, characterized in that the aerosol is mixed with 5- <lQ% methanol. 3. Device for exhaust gas decontamination in plasma-chemical etching processes, msoesonders for carrying out the method according to item 1-2. characterized in that a plasmachemischen etching a storage container is arranged nachfolgand, is connected via a provided with a reducing valve line with a Ölabscheider that the Ölabscheider below a Reaktionsgefdß is arranged at the top of the connecting line is attached to the Ölabschsider that a riser, on Reservoir, a shut-off valve and a vacuum pump, in particular a water jet pump, are arranged so that a detoxification agent from the base of the Reaktionsgeraßes starting is recycled, that at Koof the reaction vessel an atomizer nozzle with sinem upstream throttle valve is mounted, and that the Rsaktionsgefaß with a suction connected is, 4. The device according to item 3, characterized in that the oil separator and the reaction vessel are connected via a common AbluSlenung with a drain valve. 5. Performance according to item 3 and 4, characterized in that at the foot of the reaction vessel, a filler neck is attached. ö. Device according to item 3 to 5, characterized in that in the lower third of the reaction vessel above the connections of the riser, the Einfüllsiutzens, the suction and the Abfiußleirung a partition wall is attached to me connecting tube. 7. Device according to PUnkt 6, characterized in that the connecting tube ends below the junction of the riser. 8. The device according to item 3, characterized in that at the foot of the storage container ^ a screw plug is attached. 9 Device according to item 3, characterized in that a suctionable container encloses the device. H'erzu 1 Seita drawing Field of application of the invention The invention concerns a process for the detoxification of toxic fluorine- and chlorine-carbon-containing exhaust gases, as in the structure! tion of semiconductor elements by plasma-chemical etching processes arise and ѳіпс device for carrying out the process. Characteristic of the known technical solutions The creation of small structures in various materials, such as silicon, Sili2iumoxid. SiHzJumnitnd or aluminum, in the manufacture of semiconductor devices is done on a large scale by plasma chemical etching processes. Daoei are produced under the influence of a high-frequency discharge of fluorine- and / or chlorocarbon-reactive etching media. The resulting reaction products contain a high proportion of toxic substances that are discharged via the exhaust system to the environment. The resulting concentrations can be far above the MIK values. For the toxic exhaust gases occurring in plasma-chemical etching processes * structuring of semiconductor components, no methods and devices for detoxification are known in the prior art. However, it is known to detoxify gas streams contaminated with toxic substances in cleaning towers with the aid of a suitable washing liquid AJ. In the cleaning tower, the washing liquid and the gas stream are passed in countercurrent. Through the use of full bodies in the cleaning tower, a large reaction surface is achieved and, with a corresponding residence time of a gas, a high degree of conversion, ie. achieved a great detoxification effect. Oa plasmachemic etching processes take place in a vacuum, occur, by the use of vacuum pumps, oil mist together does the toxic waste gas from the recipient. These oil mist should precipitate on the filler and reduce the reaction surface and reduce the degree of conversion. Object of the invention The aim of the invention is as to avoid the pollution of the environment mittoxischsn fluorine and / or chlorcsrbcnhaltigen exhaust gases. Presentation of the veson of the invention It is the task of fatigue. a method and e ^; to provide a device which avoids the discharge of the occurring in Dlasmacbemischen etching processes for Strukiurie'ung calf conductor components toxiscnen fluorine and / or chlorcarbonnamgen waste gases to the environment. Erfindungsgernäß the object is achieved by the fact that the exiting from the recipient and separated from Olbestandteilen exhaust gas mitteis a Kaliurnhvdrcxiciaerosais, d3S mixed with an alkanol кап л in a suitable reaction vessel at atmospheric pressure and Яаигшотрегзшгг detoxifies. Be the Emgifiungsreaktior m Kaliumhydrcxidlosung releasable salts and / or ether form The device for exhaust gas detoxification in plasma-chemical Ätzprczessen consists of a storage container which is connected to the etching system. The storage tank is connected to the following oil separator via a pipe provided with a smem reducing valve. The oil separator is connected to a reaction vessel. The Verbindungslettung from the oil separator opens at the top of the reaction vessel. Starting from the bottom of the reaction vessel, a riser pipe is attached to a supply rail which is mounted above the reaction vessel and connected to a vacuum pump. The reservoir is connected via sine charge with shut-off valve and throttle valve with the arranged at the head of the reaction vessel atomizer nozzle, at the foot of the reaction vessel, a suction line is attached. The device is in a suctionable container. The process was reannealed in the associated device as described below. The Recipient of a plasmachamic Atzanlage is by means of vacuum pumps, whereby Clneoel occurred in the exhaust gas, -2- 234 906 1 pumped out discontinuously after each completed etching process. The exhaust gas is introduced into a, to the etching plant anseht eßenden storage tank, with the aid of the intermittent attack of the exhaust gas is compensated Subsequently, the exhaust gas in a subsequently arranged Ölabscheider geleiter Thereafter, the exhaust gas from his oil-de-liberated exhaust gas at the head of the subsequently arranged Reakttonsgefaßes initiated. By a partition wall in the lower third of the reaction vessel in a reaction space and a reservoir (lower third) is divided Seiag Rauine are connected by a in the partition befindliches Varbindungsrohr At the head of the reaction space is a Zersiaucerduse and compressed air KaUumhydroxidlosung sprayed in the reaction chamber now dis chemical reaction The Toxic Components of the Exhaust Gas The potassium hydroxide aerosol, the detoxified exhaust gas and the reaction products of the detoxification process pass through the connecting tube into the reservoir filled with potassium hydroxide solution. The detoxified exhaust gas collecting between the solution surface and the partition wall is discharged to the environment via a suction line. The Kaiiümhydroxidlosung is brought by closing the shut-off valve and switching on the vacuum pump VorrgcsDehalter on the riser, n the high tank, After opening the shut-off valve and switching off the vacuum pump atomization of potassium hydroxide solution is continued If the liquid level in the high tank dis dropped to a certain level, the pumping up of the calcium hydroxide solution is repeated. The potassium hydroxide solution thus circulated is regenerated cyclically, and the reaction products dissolved therein are cyclically renewed. The device for exhaust gas detoxification is arranged in my closed container by means of a vacuum pump exiting the joints of the device exhaust gases are sucked out of the container With the 'invention solution, it is possible to detoxify the plasma-etching processes inadvertently occurring toxic and oestartete with oil components exhaust gas Ausfühningsbaispiel In plasma-chemical etching processes for the consolidation of semiconductor components, the etching gas used is, in particular, tetrachloromethane, tetrafluormin andt-fluoromethane The exhaust gases, which are pumped out of the recipient in which the etching processes are carried out, usually contain fluorine water peat, F'uorphosgen and Siliziumtetrafluond. In addition, the exhaust gases contain oil components caused by vacuum pumps used for pumping out the containers. The intermittent anfalienae gas is stored and subsequently separated from the contained oil components. The subsequent detoxification is carried out at normal pressure and room temperature by means of an aerosol consisting of a 15 % iger aqueous potassium hydroxide solution carried out ззЬеі from the following reactions. HF * KCH - * KFtHjO CC F ₃ τ 4KOH -r 2KF + 2H ₂ O + KiCO ₃ S ^ t-SKCH - »4KF τ 3H ₂ O + K ₂ SiO ₃ In Aluminiumatruktunerung arises in the exhaust HCI, CCCl ₂ and AlCI ₃ , which are errtgifisi by means of a 15% aqueous Cdliumhydroxidlosung Fes comes to the following reactions HCL-> KCH - * KCl + 4.0 COCl, τ 4KCH - 2KCl - K ₂ CC ₀ - 2H ₂ O AICI ₃ -6K0H - * 3KCl-TK ₃ AI (OH) ₆ Atzt-nan sauiarsiofffraie substrate with Tnflucrmethan, so find; in the exhaust gas besides SiUziumtstratlucnd and hydrogen fluoride aucn Perrluorisobutan. The exhaust gas thus composed is detoxified with an aerosol consisting of 15% potassium hydroxide solution and 20% methanol as follows: SiF ₁₁ + 6KCH 4KF + K ₂ SiO ₃ -3H ₂ O HF ^ KQH KF + H ₂ O ^C ^ ³ C = CF ₂ -CH ₃ OH ^CF; C-CFZ-O-CH CF, CF ₃ 1,1HTnfluor2-Tnfluorrnethyl-3,3Dif] ucrpropYl- methyl ether The salts formed by the detoxification agents are soluble in the potassium hydroxide solution. The apparatus for exhaust gas decontamination in plasma-chemical etching processes will be explained below with reference to their mode of action The accompanying drawing contains a device for detoxification of the hot olymachemic auprocesses гиг Sta tterung of semiconductor devices occurring toxic fumes. After the conclusion of the plasma-chemical etching process, the recipient of the etching system is satis ed by means of VdK pumps.The toxic waste gases which accumulate continuously are introduced into a storage container 1 together with the oil mists which occur through the use of vacuum pumps. Through the storage tank T, at the foot ги Peiigungszwecken a Verschlußbchraubc ¹ 8 is a-Stoßweise Seiastung the Redkt on ₇ gefaßss4 vermeder In the line that connects the Speicherbhalter 1 with the subsequently arranged oil separator 3, there is a reducing valve. 2 with the reduction valve 2 is set to the following Gasbe'astung detoxification process л / ird After passing through deb OlabschS'ders 3, the exhaust gas enters at the top of Reakticnsgefaßes4 into the reaction space 5 on the reaction vessel 4 is formed by one partition wall 10 extending imunts ^r s third of the Reaction Table 4 is divided into a reaction space 5 and a stock holder 11. In the middle of the spray jet and a spray nozzle 6 arranged at the top of the reaction vessel Д, an aerosol of potassium hydronide solution is formed in the spray tower 5 The potassium hydroxide solution supplied to the atomizing nozzle 6 is regulated via a throttle valve 3 installed in the supply line г> т. In the reaction space 5, soluble salts of the toxic components of the alkali are formed by the above-described chemical reactions ether and / or in potassium hydroxide
Via a connecting tube 9, which connects the reaction space 5 with the reservoir "1" and z "n" the separating wall -z- 234 306 1 t. aerosol, detoxified exhaust gas and the reaction products enter the reservoir 11. The connecting tube Tightens into the potassium hydroxide solution. Between partition wall 10 and the surface of the present in the reservoir 11 Kaliumhydraxidlösung the detoxified exhaust gas collects and is discharged through the suction line 12. The potassium hydroxide solution used for detoxification is recirculated. For this purpose, a vacuum is created in by the level dss high tank 7 specific cycles by closing the shut-off valve 14 by means of a suction pipe 13 connected via a water jet pump, whereby the potassium hydroxide solution from the reservoir T1 via the riser 15 into the elevated tank? arrives. After opening the shut-off valve 14 and turning off the water-jet pump, the detoxification process is continued as described above. The Kaliumhydroxidlosung is removed after several Entcjiftungszykien via the drain valve 16 and the discharge line 19 from the reservoir 11. Pure dsium hydroxide solution is then introduced into the storage container 11 via the filler neck 17. The device гиг exhaust gas detoxification bsi plasmachemischen etching processes is arranged in a suctionable container. The exiting at joints of the device exhaust gases are sucked by a vacuum pump, so that no load can occur the working space with the toxic exhaust.