Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—After-treatment
  • H01L21/311—Etching the insulating layers by chemical or physical means
  • H01L21/31105—Etching inorganic layers
  • H01L21/31111—Etching inorganic layers by chemical means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
  • B01J39/04—Processes using organic exchangers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
  • C01B15/01—Hydrogen peroxide
  • C01B15/013—Separation; Purification; Concentration
  • C01B15/0135—Purification by solid ion-exchangers or solid chelating agents
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/19—Fluorine; Hydrogen fluoride
  • C01B7/191—Hydrogen fluoride
  • C01B7/195—Separation; Purification
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/19—Fluorine; Hydrogen fluoride
  • C01B7/191—Hydrogen fluoride
  • C01B7/195—Separation; Purification
  • C01B7/197—Separation; Purification by adsorption
  • C01B7/198—Separation; Purification by adsorption by solid ion-exchangers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
  • C01C1/00—Ammonia; Compounds thereof
  • C01C1/02—Preparation, purification or separation of ammonia
  • C01C1/024—Purification
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
  • C01C1/00—Ammonia; Compounds thereof
  • C01C1/16—Halides of ammonium
  • C01C1/162—Ammonium fluoride
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
  • H01L21/30604—Chemical etching
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• the present invention relates to semiconductor manufacture, and particularly to systems and methods for supplying ultra-high-purity hydrogen peroxide 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.
• 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.
• 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 13 cm "3 .
• 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.
• 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 present inventors have developed 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
• Hydrogen peroxide (H 2 O 2 ) is an important process chemical in semiconductor manufacturing. It is very commonly used for cleanup solutions.
• the widely used "piranha” cleanup solution typically uses H 2 O 2 + H 2 SO 4 in proportions of 30:70;
• the widely used "RCA” cleanup is a three-stage cleanup which uses hydrogen peroxide in two of the stages.
• H 2 O 2 purification on cationic and anionic resins is described in, for example: French patent application 10,431 (1953) (use of Sulfonic resins); Polish patent 50,982 (1961) (cationic + anionic resins); Polish patent 55,378 (1968); Spanish patent 328,719 (1961) (sulfonic resins, acrylic, strong base and acid [gel type]); U.S. patent 3,297,404 (1967) (use of mixed resins cationic and anionic [HCO 3 ] described in line 53 col. 2); U.S. patent 4,999,179 (1991) (sulfonic resin + anionic resin [HCO 3 ], CO2/3 + brominated).
• French patent 2,677,010 (1992) strong cationic resin + medium strength anionic resin of the gel type + non-functionalized resin
• French patent 2,677,011 (1992) medium strength anionic resin
• world PCT application 92/06918 (1992) cationic, anionic resins, description of the fluidized bed technology
• the present application describes systems and methods for preparing ultra-high-purity hydrogen peroxide on-site at an integrated circuit fabrication front-end facility.
• the starting point is high-purity aqueous H 2 O 2 (e.g. 30% H 2 O 2 ).
• the incoming aqueous H 2 O 2 is further purified in on-site purification units before it is made available for combination with other reagents.
• the on-site purification units consist of anionic and cationic exchange beds, together with one or more paniculate filters.
• the present application also describes systems and methods for preparing ultra-high- purity mixed cleanup solutions on-site at an integrated circuit fabrication front-end facility, by combining hydrogen peroxide which has been ultrapurified on-site with an acid or base which has been ultrapurified on-site.
• 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 - HC1 + 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 Shiraki, "Low Temperature Surface Cleaning of Silicon and its application to Silicon MBE," 133 J. ELECTROCHEM. SOC. 666 (1986), which is hereby incorporated by reference.
• the RCA basic cleanup solution is typically NH 4 OH + H 2 O 2 + H 2 O in proportions of 1:1 :5 or 1:2:7.
• RCA basic cleanup (or analogous cleanup solutions) is generated at the site of a wafer manufacturing plant, by combination of ultra-pure ammonia which has been purified on-site with ultra-pure hydrogen peroxide which has been purified on-site.
• ultra-pure ammonia which has been purified on-site
• ultra-pure hydrogen peroxide which has been purified on-site.
• the RCA acid cleanup solution is typically HC1 + H 2 O 2 + H 2 O in proportions of 1:1:6 or 1:2:8. According to one of the innovative teachings disclosed herein, RCA acid cleanup (or analogous cleanup solutions) is generated at the site of a wafer manufacturing plant, by combination of ultra-pure HC1 which has been purified on-site with ultra-pure hydrogen peroxide which has been purified on-site. Thus purity is increased, and the risk of undetected accidental contamination is reduced.
• Figure 1 shows an on-site system for purification of aqueous hydrogen peroxide at a semiconductor facility.
• Figure 2 is a block diagram of semiconductor cleanup stations, in a wafer fabrication facility in which the ammonia purification of Figure 1 may be incorporated.
• Figure 3 shows generation of an RCA cleanup solution on-site, at a wafer fabrication facility, using two components (in addition to ultrapure water) which have both been ultrapurified on-site at the same facility.
• the target for purity of the aqueous H 2 O 2 is:
• FIG. 1 shows an on-site system for purification of aqueous hydrogen peroxide at a semiconductor facility.
• incoming hydrogen peroxide preferably already high-purity
• the on-site ultrapurification system uses an anionic exchange column in combination with a cationic exchange column.
• anionic exchange column in combination with a cationic exchange column.
• other conventional techniques for sub-ppb polishing can also be used.
• a filtration stage is preferably used downstream of the exchange resin columns, to remove any particulates which may have been introduced by the columns.
• Anionic Exchange Column This column is preferably initially loaded with bicarbonate ions.
• Bicarbonate preconditioning is shown, e.g., by US patents 3294488 or 3305314, which are hereby incorporated by reference.
• This is preferably achieved by use of a concentrated NH 4 HCO 3 solution.
• Possible alternatives include use of an alkali bicarbonate, which requires removal of the alkali metal ions, or use of CO 2 , which is inefficient due to the low solubility of CO 2 .
• the anionic resin is IRA 958 from Rohm and
• This column is preferably initially loaded with acid. This can be done, e.g., with a wash in e.g. a 10% solution of H 2 SO 4 .
• the cationic resin is Rohm and Haas A-35.
• Figure 3 shows generation of an RCA cleanup solution on-site, at a wafer fabrication facility, using two components (in addition to ultrapure water) which have both been ultrapurified on-site at the same facility.
• the first unit in the cleaning line is a resist stripping station 41 where aqueous hydrogen peroxide 42 and sulfuric acid 43 are combined and applied to the semiconductor surface to strip off the resist. This is succeeded by a rinse station 44 where deionized water is applied to rinse off the stripping solution. Immediately downstream of the rinse station 44 is a cleaning station 45 where an aqueous solution of ammonia and hydrogen peroxide are applied. This solution is supplied in one of two ways. In the first, aqueous ammonia 31 from the dissolving unit 29 is combined with aqueous hydrogen peroxide 46, and the resulting mixture 47 is directed to the cleaning station 45.
• pure gaseous ammonia 32 is bubbled into an aqueous hydrogen peroxide solution 48 to produce a similar mixture 49, which is likewise directed to the cleaning station 45.
• the semiconductor passes to a second rinse station 50 where deionized water is applied to remove the cleaning solution.
• the next station is a further cleaning station 54 where aqueous solutions of hydrochloric acid 55 and hydrogen peroxide 56 are combined and applied to the semiconductor surface for further cleaning.
• a final rinse station 57 where deionized water is applied to remove the HC1 and H 2 O 2
• a drying station 58 is followed by a drying station 58.
• the wafer or wafer batch 51 will be held on a wafer support 52, and conveyed from one workstation to the next by a robot 63 or some other conventional means of achieving sequential treatment.
• the means of conveyance may be totally automated, partially automated or not automated at all.
• purified HC1 for the acid cleaning station 54 may be prepared and supplied on site in a manner similar to that of the ammonia purification system of FIG. 1.
• FIG. 2 is just one example of a cleaning line for semiconductor fabrication.
• cleaning lines for high-precision manufacture can vary widely from that shown in FIG. 2, either eliminating one or more of the units shown or adding or substituting units not shown.
• the concept of the on-site preparation of high-purity hydrogen peroxide, however, in accordance with this invention is applicable to all such systems.
• ammonia and hydrogen peroxide as a semiconductor cleaning medium at workstations such as the cleaning station 45 shown in FIG. 2 is well known throughout the industry. While the proportions vary, a nominal system would consist of deionized water, 29% ammonium hydroxide (weight basis) and 30% hydrogen peroxide (weight basis), combined in a volume ratio of 6: 1 : 1. This cleaning agent is used to remove organic residues, and, in conjunction with ultrasonic agitation at frequencies of approximately 1 MHz, removes particles down to the submicron size range.
• the on-site system for ultrapurification of H 2 O 2 and generation of ultrapure cleaning solution will be connected to the point of use in the production line by piping which does not cause any exposure to an uncontrolled ambient.
• the distance of travel between the unit and the production line may be short (in the case of a dedicated point-of-use mixing facility), or more preferably the ultrapure cleaning solution generator may be connected to multiple points of use through ultraclean piping.
• intermediate holding tanks may be used to average the flow rate to compensate for varying demand, but in any case the cleaning solutions are maintained in an ultrapure environment, and are never exposed to ambient contamination. This avoids the risks of contamination due to packaging, transport, or transfer between containers.
• the distance between the point at which the cleanup solution leaves the generation system and its point of use on the production line may be from one foot (30 cm) up to 1,000 meters or more (in the case where ultraclean piping is routed between buildings at a single manufacturing site).
• Transfer can be achieved through an ultra-clean transfer line of a material which does not introduce contamination.
• stainless steel or polymers such as high density polyethylene or fluorinated polymers can be used successfully.
• deionized water purified in accordance with semiconductor manufacturing standards
• concentration adjustment flushing, or dissolution of gasses.
• dissolution of gasses The standards commonly used in the semiconductor industry are well known among those skilled in the art.
• Typical standards for the purity of the water resulting from these processes are a resistivity of at least about 15 megohm-cm at 25°C (typically 18 megohm-cm at 25°C), less than about 25ppb of electrolytes, a paniculate content of less than about 150/cm 3 and a particle size of less than 0.2 micron, a microorganism content of less than about 10/cm 3 , and total organic carbon of less than lOOppb.
• a high degree of control over the product concentration and hence the flow rates is preferably maintained, by precise monitoring and metering using known equipment and instrumentation. A convenient means of achieving this uses ultrasonic wave propagation to monitor density. Other methods will be readily apparent to those skilled in the art.
• the innovative concepts described in the present application can be modified and varied over a tremendous range of applications, and accordingly the scope of patented subject matter is not limited by any of the specific exemplary teachings given.
• 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.

Priority Applications (4)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26789687

Family Applications (1)

Country Status (4)

Cited By (9)

Families Citing this family (7)

Citations (3)

Family Cites Families (4)

• 1996
  • 1996-06-05 WO PCT/US1996/009556 patent/WO1996039237A1/en not_active Application Discontinuation
  • 1996-06-05 CN CN96194534A patent/CN1089616C/zh not_active Expired - Fee Related
  • 1996-06-05 JP JP9501851A patent/JPH11509980A/ja active Pending
  • 1996-06-05 AU AU61036/96A patent/AU6103696A/en not_active Abandoned
  • 1996-06-05 CN CN96194535A patent/CN1082402C/zh not_active Expired - Fee Related
  • 1996-06-05 JP JP50185297A patent/JP2002514968A/ja active Pending

Patent Citations (3)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events