EP0835169A1 - Fabrication sur site d'acide chlorhydrique ultrapur pour le traitement des semi-conducteurs - Google Patents

Fabrication sur site d'acide chlorhydrique ultrapur pour le traitement des semi-conducteurs

Info

Publication number
EP0835169A1
EP0835169A1 EP96919224A EP96919224A EP0835169A1 EP 0835169 A1 EP0835169 A1 EP 0835169A1 EP 96919224 A EP96919224 A EP 96919224A EP 96919224 A EP96919224 A EP 96919224A EP 0835169 A1 EP0835169 A1 EP 0835169A1
Authority
EP
European Patent Office
Prior art keywords
hcl
vapor
liquid
purity
gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96919224A
Other languages
German (de)
English (en)
Other versions
EP0835169A4 (fr
Inventor
Joe G. Hoffman
R. Scot Clark
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Air Liquide America Corp
Original Assignee
Startec Ventures Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/US1995/007649 external-priority patent/WO1996039358A1/fr
Application filed by Startec Ventures Inc filed Critical Startec Ventures Inc
Priority claimed from PCT/US1996/009555 external-priority patent/WO1996039264A1/fr
Publication of EP0835169A1 publication Critical patent/EP0835169A1/fr
Publication of EP0835169A4 publication Critical patent/EP0835169A4/fr
Withdrawn legal-status Critical Current

Links

Definitions

  • the present invention relates to systems and methods for supplying ultra-high-purity HCl for semiconductor manufacture.
  • Contamination is generally an overwhelmingly important concern in integrated circuit manufacturing.
  • cleanup steps of one kind or another such cleanup steps may need to remove organic con ⁇ taminants, metallic contaminants, photoresist (or inorganic residues thereof), byproducts of etching, native oxides, etc.
  • Plasma etching has many attractive capabilities, but it is not adequate for cleanup. There is simply no available chemistry to remove some of the most undesirable impurities, such as gold. Thus wet cleanup processes are essential to modern semiconductor processing, and are likely to remain so for the foreseeable future.
  • Plasma etching is performed with photoresist in place, and is not directly followed by high-temperature steps. Instead the resist is stripped, and a cleanup is then necessary.
  • the materials which the cleanup must remove may include: photoresist residues (organic polymers); sodium; Alkaline earths (e.g. calcium or magnesium); and heavy metals (e.g. gold). Many of these do not form volatile halides, so plasma etching can't carry them away. Cleanups using wet chemistries are required.
  • Integrated circuit structures use only a few dopant species (boron, arsenic, phosphorus, and sometimes antimony) to form the required p-type and n-type doped regions.
  • dopant species boron, arsenic, phosphorus, and sometimes antimony
  • many other species are electrically active dopants, and are highly undesirable contaminants. Many of these contaminants can have deleterious effects, such as increased junction leakage, at concentrations well below 10 cm .
  • some of the less desirable contaminants segregate into silicon, i.e. where silicon is in contact with an aqueous solution the equilibrium concentration of the contaminants will be higher in the silicon than in the solution.
  • some of the less desirable contaminants have very high diffusion coefficients, so that introduction of such dopants into any part of the silicon wafer will tend to allow these contaminants to diffuse throughout, including junction locations where these contaminants will cause leakage.
  • all liquid solutions which will be used on a semiconductor wafer should preferably have extremely low levels of all metal ions.
  • concentration of all metals combined should be less than 300 ppt (parts per trillion), and less than 10 ppt for any one metal, and less would be better.
  • contamination by both anions and cations must also be controlled. (Some anions may have adverse effects, e.g. complexed metal ions may reduce to mobile metal atoms or ions in the silicon lattice.)
  • Front end facilities normally include on-site purification systems for preparation of high-purity water (referred to as "DI" water, i.e. deionized water).
  • DI high-purity water
  • process chemicals in the purities needed.
  • the parent application described a method for preparing ultra-high-purity ammonia, in an on-site system located at the semiconductor wafer production site, by: drawing ammonia vapor from a liquid ammonia reservoir, passing the ammonia vapor through a microfiltration filter, and scrubbing the filtered vapor with high-pH purified water (preferably deionized water which has been allowed to equilibrate with the ammonia stream).
  • high-pH purified water preferably deionized water which has been allowed to equilibrate with the ammonia stream.
  • the drawing of the ammonia vapor from the supply reservoir serves by itself as a single-stage distillation, eliminating nonvolatile and high-boiling impurities, such as alkali and alkaline earth metal oxides, carbonates and hydrides, transition metal halides and hydrides, and high-boiling hydrocarbons and halocarbons.
  • nonvolatile and high-boiling impurities such as alkali and alkaline earth metal oxides, carbonates and hydrides, transition metal halides and hydrides, and high-boiling hydrocarbons and halocarbons.
  • the reactive volatile impurities that could be found in commercial grade ammonia, such as certain transition metal halides, Group III metal hydrides and halides, certain Group IV hydrides and halides, and halogens, previously thought to require distillation for removal, were discovered to be capable of removal by scrubbing to a degree which is adequate for high-precision operations. This is a very surprising discovery, since scrub
  • the present application discloses systems and methods for preparation of ultrapure chemicals on-site at a semiconductor manufacturing facility, so that they can be piped directly to the points of use.
  • the disclosed systems are very compact units which can be located in the same building as a front end (or in an adjacent building), so that handling is avoided.
  • Hydrochloric Acid An important family of semiconductor processing chemicals is HCl, in gaseous and aqueous forms. Liquid hydrochloric acid is also widely used in the acid cleanup portion of the standard RCA cleanup.
  • the starting material is commercial-grade anhydrous HCl.
  • a first purification step is provided simply by evaporation.
  • HCl has a vapor pressure of 613 psig at 70°F, and 1185 psig at 124.5°F, so the vapor pressure always provides ample transfer pressure from the bulk storage tank.
  • Preferably HCl vapor is drawn directly from the tank.
  • liquid HCl is transferred in batches from the bulk storage tank, and evaporated in an evaporation chamber under controlled temperature and pressure.
  • the purified gaseous HCl can now be dissolved in water to produce concentrated hydrochloric acid.
  • the present application discloses preparation of mixed cleanup solutions, such as the RCA acidic cleanup and the RCA basic cleanup, at the site of a wafer fabrication facility, from ingredients which themselves have been ultrapurified at the same site.
  • the RCA cleanup includes: 1) solvent wash to remove gross organics - in tetrachloroethylene or comparable solvent; 2) basic cleanup - NH 4 OH + H 2 O 2 + H 2 O; and 3) acid cleanup - HCl + H 2 O 2 + H 2 O.)
  • solvent wash to remove gross organics - in tetrachloroethylene or comparable solvent
  • basic cleanup - NH 4 OH + H 2 O 2 + H 2 O
  • Shiraki cleanup is an aggressive, pre-epitaxy cleanup, which adds a nitric acid step to the cleanup sequence, and uses somewhat higher temperatures and concentrations. See Ishizaki and
  • the RCA acid cleanup solution is typically HCl + H 2 O 2 + H 2 O in proportions of 1 :1 :6 or 1 :2:8.
  • RCA acid cleanup (or analogous cleanup solutions) is generated at the site of a wafer manufacturing plant, by combination of ultra-pure HCl which has been purified on-site with ultra-pure hydrogen peroxide which has been purified on-site.
  • ultra-pure HCl which has been purified on-site
  • ultra-pure hydrogen peroxide which has been purified on-site.
  • Figure 1 is an engineering flow diagram of one example of a unit for the production of ultrapure hydrochloric acid.
  • Figure 2 is a block diagram of a semiconductor fabrication line in which the purification unit of Figure 1 may be incorporated.
  • Figure 3 is a block diagram of semiconductor cleanup stations, in a wafer fabrication facility in which the hydrochloric acid purification of Figure 1 may be incorporated.
  • vapor-phase HCl is first drawn from the vapor space in a liquid HCl supply reservoir. Drawing vapor in this manner serves as a single-stage distillation, leaving certain solid and high-boiling impurities behind in the liquid phase.
  • the supply reservoir can be any conventional supply tank or other reservoir suitable for containing HCl, and the HCl can be in anhydrous form or an aqueous solution (preferably anhydrous).
  • the reservoir can be maintained at atmospheric pressure or at a pressure above atmospheric if desired to enhance the flow of the HCl through the system.
  • the reservoir is preferably heat controlled, so that the temperature is within the range of from about 10° to about 50°C, preferably from about 15° to about 35°C, and most preferably from about 20° to about 25°C.
  • Impurities that will be removed as a result of drawing the HCl from the vapor phase include metals of Groups I and II of the Periodic Table, as well as complexed forms of these metals which may form as a result of the contact with HCl.
  • oxides and carbonates of these metals as well as hydrides such as beryllium hydride and magnesium hydride; Group III elements and their oxides, as well as adducts of hydrides and halides of these elements; transition metal hydrides; and heavy hydrocarbons and halocarbons such as pump oil.
  • the HCl drawn from the reservoir is passed through a filtration unit to remove any solid matter entrained with the vapor.
  • Microfiltration and ultrafiltration units and membranes are commercially available and can be used. The grade and type of filter will be selected according to need. The presently preferred embodiment uses a gross filter, followed by a 0.1 micron filter, in front of the ionic purifier, and no filtration after the ionic purifier.
  • the filtered vapor is then passed to a scrubber in which the vapor is scrubbed with low-pH purified (preferably deionized) water.
  • the low-pH water is preferably an aqueous HCl solution, with the concentration raised to saturation by recycling through the scrubber.
  • the scrubber may be conveniently operated as a conventional scrubbing column in countercurrent fashion.
  • the operating temperature is not critical, the column is preferably run at a temperature ranging from about 10° to about 50°C, preferably from about 15° to about 35°C.
  • the operating pressure is not critical, although preferred operation will be at a pressure of from about atmospheric pressure to about 30 psi above atmospheric.
  • the column will typically contain a conventional column packing to provide for a high degree of contact between liquid and gas, and preferably a mist removal section as well.
  • the column has a packed height of approximately 3 feet (0.9 meter) and an internal diameter of approximately 7 inches (18 cm), to achieve a packing volume of 0.84 cubic feet (24 liters), and is operated at a pressure drop of about 0.3 inches of water (0.075 kPa) and less than 10% flood, with a recirculation flow of about 2.5 gallons per minute (0.16 liter per second) nominal or 5 gallons per minute (0.32 liter per second) at 20% flood, with the gas inlet below the packing, and the liquid inlet above the packing but below the mist removal section.
  • Preferred packing materials for a column of this description are those which have a nominal dimension of less than one-eighth of the column diameter.
  • the mist removal section of the column will have a similar or more dense packing, and is otherwise conventional in construction. It should be understood that all descriptions and dimensions in this paragraph are examples only. Each of the system parameters may be varied.
  • startup is achieved by first saturating deionized water with HCl to form a solution for use as the starting scrubbing medium.
  • HCl HCl
  • a small amount of liquid in the column sump is drained periodically to remove accumulated impurities.
  • impurities that will be removed by the scrubber include reactive volatiles such as metal halides; halides and hydrides of phosphorus, arsenic, and antimony; transition metal halides in general; and Group III and Group VI metal halides and hydrides.
  • the units described up to this point may be operated in either batchwise, continuous, or semi-continuous manner. Continuous or semi-continuous operation is preferred.
  • the volumetric processing rate of the HCl purification system is not critical and may vary widely. In most operations for which the present invention is contemplated for use, however, the flow rate of HCl through the system will be within the range of about 200 cc h to thousands of liters per hour.
  • the HCl leaving the scrubber can be further purified prior to use, depending on the particular type of manufacturing process for which the HCl is being purified.
  • a dehydration unit and a distillation unit in the system will be beneficial.
  • the distillation column may also be operated in either batchwise, continuous, or semi-continuous manner. In a batch operation, a typical operating pressure might be 300 pounds per square inch absolute (2,068 kPa), with a batch size of 100 pounds (45.4 kg).
  • the column in this example has a diameter of 8 inches (20 cm), a height of 72 inches (183 cm), operating at 30% of flood, with a vapor velocity of 0.00221 feet per second (0.00067 meter per second), a height equivalent to a theoretical plate of 1.5 inches (3.8 cm), and 48 equivalent plates.
  • the boiler size in this example is about 18 inches (45.7 cm) in diameter and 27 inches (68.6 cm) in length, with a reflux ratio of 0.5, and recirculating chilled water enters at 60°F (15.6°C) and leaves at 90°F (32.2°C). Again, this is merely an example; distillation columns varying widely in construction and operational parameters can be used.
  • the purified HCl may be used as a purified gas or as an aqueous solution, in which case the purified HCl is dissolved in purified (preferably deionized) water.
  • the proportions and the means of mixing are conventional.
  • a flow chart depicting one example of an HCl purification unit in accordance with this invention is shown in Figure 1.
  • Liquid HCl is stored in a reservoir 11.
  • HCl vapor 12 is drawn from the vapor space in the reservoir, then passed through a shutoff valve 13, then through a filter 14.
  • the filtered HCl vapor 15.
  • a scrubbing column 17 which contains a packed section 18 and a mist removal pad 19.
  • Saturated aqueous HCl 20 flows downward as the HCl vapor flows upward, the liquid being circulated by a circulation pump 21, and the liquid level controlled by a level sensor 22.
  • Waste 23 is drawn off periodically from the retained liquid in the bottom of the scrubber.
  • Deionized water 24 is supplied to the scrubber 17, with elevated pressure maintained by a pump 25.
  • the scrubbed HCl 26 is directed to one of three alternate routes. These are: (1) A distillation column 27 where the HCl is purified further. The resulting distilled HCl
  • a dissolving unit 29 where the HCl is combined with deionized water 30 to form an aqueous solution 31, which is directed to the point of use.
  • the aqueous solution can be collected in a holding tank from which the HCl is drawn into individual lines for a multitude of point-of-use destinations at the same plant.
  • a transfer line 32 which carries the HCl in gaseous form to the point of use.
  • the second and third of these alternatives which do not utilize the distillation column 27, are suitable for producing HCl with less than 100 parts per trillion of any metallic impurity.
  • the inclusion of the distillation column 27 can be advantageous. In such cases the distillation column is used to remove non-condensables such as oxygen and nitrogen, that might interfere with cleanup.
  • a dehydration unit can optionally be incorporated into the system between the scrubber 17 and the distillation column 27, as an option, depending on the characteristics and efficiency of the distillation column.
  • the resulting stream be it gaseous HCl or an aqueous solution, may be divided into two or more branch streams, each directed to a different use station, the purification unit thereby supplying purified HCl to a number of use stations simultaneously.
  • the sampling apparatus was constructed from a CGA to 1/4" tube adapter and a Nupro bellows sealed valve with 1/4" tube fittings, both stainless steel.
  • the outlet of the valve was fitted with a short piece of 1/4" Teflon tubing so that the liquid or vapor could be conducted directly to the sample bottle. In this manner the aqueous HCl sample could be prepared directly in the sample bottle, obviating the need for liquid transfers in an uncontrolled environment.
  • Sample bottles were prepared by thoroughly DI rinsing and discarding the rinse four times before adding approximately 100 cc of DI and capping the bottles. Samples were taken by bubbling the HCl from the selected source and method into the DI previously added to the sample bottle. In most cases HCl addition was continued until the solution in the sample bottle was saturated as evidenced by the HCl passing through the solution and escaping to the hood exhaust. At saturation the sample solution was quite hot to the touch and the sample bottle partially collapsed after capping and cooling.
  • IP simulated ionic purifier
  • the disclosed innovative techniques are not strictly limited to manufacture of integrated circuits, but can also be applied to manufacturing discrete semiconductor components, such as optoelectronic and power devices.
  • the disclosed innovative techniques can also be adapted to manufacture of other technologies where integrated circuit manufacturing methods have been adopted, such as in thin-film magnetic heads and active-matrix liquid-crystal displays; but the primary application is in integrated circuit manufacturing, and applications of the disclosed techniques to other areas are secondary.
  • additives can be introduced into the purification water if desired, although this is not done in the presently preferred embodiment.
  • the primary embodiment is an on-site purification system.
  • the disclosed purification system can also be adapted to operate as a part of a manufacturing unit to produce ultra-high-purity chemicals for shipment; however, this alternative embodiment does not provide the advantages of on-site purification as discussed above.
  • Such applications encounter the inherent risks of handling ultra-high-purity chemicals, as discussed above; but for customers who require packaged chemicals (with the attendant handling), the disclosed innovations at least give a way to achieve an initial purity which is higher than that available by other techniques. Again, in such applications a dryer stage may also be used after the ionic purifier.
  • the primary embodiment is directed to providing ultrapure aqueous chemicals, which are most critical for semiconductor manufacturing.
  • the disclosed system and method embodiments can also be used for supply of purified gas streams. (In many cases, use of a dryer downstream from the purifier will be useful for this.)
  • piping for ultrapure chemical routing in semiconductor front ends may include in-line or pressure reservoirs.
  • references to "direct" piping in the claims do not preclude use of such reservoirs, but do preclude exposure to uncontrolled atmospneres.

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  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

On prépare sur site du HCl hautement pur à utiliser dans la fabrication de semi-conducteurs, en prélevant de la vapeur de HCl (12) d'un réservoir de HCl liquide (11), et en épurant la vapeur filtrée (15) dans une tour de lavage à solution aqueuse de faible pH (17).
EP96919224A 1995-06-05 1996-06-05 Fabrication sur site d'acide chlorhydrique ultrapur pour le traitement des semi-conducteurs Withdrawn EP0835169A4 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
WOPCT/US95/07649 1995-06-05
PCT/US1995/007649 WO1996039358A1 (fr) 1995-06-05 1995-06-05 Purification de gaz ammoniac jusqu'au niveau requis pour son utilisation dans la fabrication de composants electroniques
US49941395A 1995-07-07 1995-07-07
US3871295P 1995-07-07 1995-07-07
US499413 1995-07-07
PCT/US1996/009555 WO1996039264A1 (fr) 1995-06-05 1996-06-05 Fabrication sur site d'acide chlorhydrique ultrapur pour le traitement des semi-conducteurs

Publications (2)

Publication Number Publication Date
EP0835169A1 true EP0835169A1 (fr) 1998-04-15
EP0835169A4 EP0835169A4 (fr) 1999-12-15

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Application Number Title Priority Date Filing Date
EP96919224A Withdrawn EP0835169A4 (fr) 1995-06-05 1996-06-05 Fabrication sur site d'acide chlorhydrique ultrapur pour le traitement des semi-conducteurs

Country Status (1)

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EP (1) EP0835169A4 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109261108A (zh) * 2018-11-27 2019-01-25 衡阳恒荣高纯半导体材料有限公司 一种二氧化锗制备水解反应釜

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
No further relevant documents disclosed *
See also references of WO9639264A1 *

Also Published As

Publication number Publication date
EP0835169A4 (fr) 1999-12-15

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