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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
  • H01L21/31144—Etching the insulating layers by chemical or physical means using masks
• • 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
  • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
  • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
  • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
• • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
  • H01L21/308—Chemical or electrical treatment, e.g. electrolytic etching using masks
  • H01L21/3083—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
  • H01L21/3086—Chemical or electrical treatment, e.g. electrolytic etching using masks characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table 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
  • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
  • H01L21/321—After treatment
  • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
  • H01L21/32139—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer using masks

Definitions

• the present invention relates generally to etching wafers, and more particularly to a method and composition for use in etching wafers used in the production of semiconductor devices.
• Photolithography is widely used for patterning photoresist material in the production of semiconductor devices. It is desirable to perform photolithography with light of a small wavelength to allow a reduction in the design rule to create smaller semiconductor devices. For example, 193 nm lithography using an Argon Fluoride (ArF) light source may be used to obtain 0.1 Dm to 0.07 Dm sizes. After a pattern of photoresist material has been provided on a wafer, the exposed layer of the wafer can be etched.
• ArF Argon Fluoride
• the photoresist material itself can be substantially removed which can expose the area that the photoresist is intended to protect.
• the etchant can cause the photoresist material to deform or twist, which in turn causes the features resulting from etching to be deformed.
• the intended feature of a straight track could be well defined by photoresist material.
• etching to define the actual track can result in a wavy track actually being formed owing to the twisting and deformation of the photoresist material caused by the etching mechanism.
• the inability to control the shape of the features being etched can result, in the worst case, in device failure, or at least in non-reproducibility.
• a method for etching a wafer having a pattern of photoresist material thereon includes curing the photoresist material with a bromine containing plasma. Then the etching of the wafer is carried out.
• a method for curing a pattern of photoresist material on a wafer includes providing a bromine containing plasma.
• the photoresist material is exposed to the plasma.
• a layer of the wafer below the photoresist material is not etched through.
• a method for etching a wafer having a pattern of photoresist material thereon includes providing an etchant composition.
• the etchant composition generates a plasma active to etch a layer of the wafer below the photoresist material.
• a bromine containing plasma is also provided. The bromine containing plasma is active to harden the photoresist material.
• a composition for etching a wafer having a pattern of photoresist material thereon is also disclosed.
• the composition comprises a fluorocarbon or a fluorohydrocarbon and a bromine containing molecule.
• Figure 1 is a schematic cross sectional view of a wafer on which a method according to the invention can be used;
• Figure 2 is a flow chart illustrating the steps of an example of the method of the invention;
• Figure 3 is a schematic cross sectional view of a wafer on which a method according to the invention can be used;
• Figure 4 is a flow chart illustrating the steps of a further example of the method of the invention.
• Figures 5 A, B and C respectively show electron microscope pictures of cross sectional and perspective views of a wafer etched according to the method illustrated in figure 2; and Figures 6 A, B and C respectively show electron microscope pictures of cross sectional and perspective views of a wafer etched according to the method illustrated in figure 4.
• like reference numerals refer to like components and elements.
• Figure 1 shows a schematic cross section through a wafer 100 at a stage during the fabrication of a semiconductor device.
• a feature to be fabricated in the device is defined by 193nm photoresist material 102.
• 193nm photoresist material is used to refer to a photoresist material that can be patterned by radiation of wavelength 193nm.
• Suitable such materials inlcude alicyclic methacrylate (acrylate) as provided under the trade names PAR 707, PAR 723 and PAR 710 by Sumitomo Corporation.
• Photoresist feature 102 is approximately 2600A thick. Typically, the thickness of the 193nm photoresist material layer is between approximately 2200A and 3300A. Photo imaging processes known in the art may be used to create the photoresist feature, which forms the photoresist mask. Photoresist feature 102 is above a layer 104 of anti reflection coating ("ARC"), which is typically between approximately 300 and 80 ⁇ A thick.
• ARC anti reflection coating
• the ARC includes bottom antireflective coating (BARC), and is typically a hydrocarbon based material similar to that of the photoresist material.
• the wafer 100 includes a hardmask layer 106, which may be made of silicon nitride (SiN), which is typically approximately 500 to 2000A thick. In the alternative, the hard mask layer may be TEOS (tetra ethyl oxysilicate), silicon oxide, or a composite of the above materials.
• a layer of tungsten (W) 108 and a layer of tungsten nitride (WN) 110 can optionally be included to improve device speed, followed by a layer 112 of polysilicon material.
• a thin layer of gate oxide 114 is included, above a silicon substrate 116. Such a wafer substrate is an intermediate product in the fabrication of a EDRAM or DRAM device.
• the photoresist material 102 defines a track feature, which is to be propagated onto the wafer as illustrated by dashed lines 118, 120 by etching of the wafer.
• the feature that the photoresist material is patterned to produce will depend on the design of the chip. Different types of features can be defined by the photoresist material.
• the photoresist material can define a hole or a 'T' or 'U' shaped feature.
• Figure 2 shows a flow chart illustrating a method 200 by which the feature can be etched. The method can be carried out using any plasma etching tool or device capable of producing a high density plasma. Suitable tools include the TCP family of plasma processing devices as provided by Lam Research Corporation of Fremont, CA.
• the DPS family of tools and similar as provided by Applied Materials, hie, the SCCM tools provided by Tokyo Electron Limited and the ECR family of tools as provided by Hitachi Ltd are also suitable.
• the method 200 is an essentially two step method. In the first step, the photoresist material 102 is hardened and otherwise stabilized without significant etching of the wafer. In a subsequent step, the wafer is actually etched so as to purposefully remove material from layers below and unprotected by the photoresist material. Any material removed by the bromine containing plasma is not intended, or should not be sufficient, to remove an entire layer of the wafer below the photoresist material layer. The main etch step etches the layer of the wafer in which the structural feature being etched is defined.
• bromine containing gas is introduced into the plasma processing chamber of the device 212.
• the bromine containing gas is hydrogen bromide (HBr).
• the plasma processing tool is operated under conditions to allow a high density plasma to be struck in the chamber and sustained 214.
• a high density plasma is considered to be a plasma having a density of greater than approximately lxlO 10 ions/cm 3 .
• the high density plasma can have a density in the range of approximately lxlO 10 to lxlO 13 ions/cm 3 .
• the photoresist material is exposed to the plasma, and bromine species in the plasma is active to cure the photoresist material 216 so that it is harder and more physically robust.
• a high density plasma is used in the photoresist curing, pre-main etch step 216, with the plasma processing device operated at a low pressure and high power.
• the HBr in the curing step does not carry out significant etching of the wafer, but rather strengthens the photoresist material 102.
• hydrogen bromide is the preferred source of bromine species for the plasma
• other bromine containing molecules can be used in the curing plasma, such as SiBr 4 , CH 3 Br, Br 2 , C 2 H 5 Br and higher bromine containing hydrocarbons.
• additional molecules can be included in the plasma gas mixture, such as inert gases.
• such a mixture for curing would not have significant amounts of active etchants such as hydrocarbons and fluorine containing molecules.
• An example of suitable operating conditions for the HBr cure step would be a plasma processing chamber pressure of approximately 5mT, a power of 1200W, substantially 0 bias voltage applied to a chuck electrode, a HBr gas flow rate of lOOsccm (standard cubic centimeters per minute) and a cure time of approximately 60 seconds.
• a bias potential of between 0 to 500V can be used, of between 0 to 250V is preferred and of between 0 to 30V is most preferred.
• Equivalent bias power ranges are approximately 0 to 740W, 0 to 350W and 0 to 40W respectively.
• Insubstantial removal of material can also be considered to occur based on the amount of photoresist material that is removed during the curing step. Not more than approximately 60 ⁇ A of photoresist material can be lost, preferably not more than approximately 500A are lost, more preferably not more than approximately 40 ⁇ A are lost and most preferably not more than 30 ⁇ A of photoresist material are lost.
• the proportion of photoresist material lost out of the thickness of photoresist material originally present can be not more than approximately 30%, preferably not more than 12% and more preferably not more than 5%.
• Insubstantial removal of material can also be considered to occur based on the amount of the ARC layer material that is removed during the curing step. Not more than 85% of the ARC layer can be removed, preferably not more than 75%, more preferably not more than 70% and most preferably not more than 60%. Substantial etching can be considered to have occurred if etching through the ARC layer occurs during the pre-main etch curing step.
• the HBr plasma is pumped from the plasma chamber and the etchant gas mixture is introduced 218 into the plasma chamber so as to start the main etch of the feature.
• the composition of the etchant gas mixture is selected so as to effectively etch the intended layer of the wafer.
• the next layer to be etched is the ARC layer 104.
• a suitable etchant gas mixture is CF 4 at a flow rate of 40 seem and He at a flow rate of 120 seem, although other fluorocarbons providing a source of fluorine for etching the ARC material can be used.
• a mixture of HBr and O 2 or a mixture of Cl 2 and O 2 can be used to etch through the ARC layer.
• the ARC material can be organic or inorganic.
• Example operating parameters for the plasma etching device are a plasma chamber pressure of 7mT, TCP power of 600W, a 100V bias voltage applied to the chuck electrode (equivalent to ⁇ 46W bias power) and an end point of +30% over etch.
• the ARC layer is etched as part of the main etching step 220, which actually forms the feature defined by the photoresist material.
• the etch of the ARC layer can be carried out before the curing of the photoresist.
• the main etch through the layers under and not protected by the photoresist is then carried out after curing of the photoresist.
• a photoresist trimming step can be included in the method.
• the curing step can then be carried out before the ARC etch and trim steps, or after the ARC etch and trim steps or between the ARC etch and trim steps.
• the main etch 220 can include a number of steps in which different etch chemistries and operating parameters are used to etch the different layers of the wafer. Steps 218 and 220 are repeated, as indicated by step 221, for each different main etch step required.
• the etchant gas composition for the hardmask 106 etch step comprises CF 4 at a flow rate of 40 seem, CH 2 F 2 at a flow rate of 20 seem and He at a flow rate of 80 seem.
• Suitable plasma processing device operating parameters are a pressure of 7mT, TCP power of 1000W and chuck bias voltage of 400V (equivalent to a bias power of 300W).
• Other gases may be used in the hardmask etching gas composition, including CHF 3 in place of CH 2 F 2 , and the addition of oxygen and/or NF 3 .
• tungsten 108, tungsten nitride 110 and other layers can then all be etched as required using etching chemistries that are well known to persons of skill in this art.
• figure 5 A shows an electron microscope picture of a cross section 502 through the photoresist and SiN layers of a wafer etched according to the above described method and figure 5B shows a perspective view 504.
• FIG. 1400A deep layer of photoresist material 506 is present on the SiN hard mask layer 508, and a straight, well defined feature has been etched as shown in Figure 5C.
• Figure 3 shows a cross section through a further wafer 120 illustrating a further embodiment of the invention.
• the wafer includes a 193nm photoresist feature 122, which has been patterned on an ARC layer 124.
• a layer of polysilicon material 126 is present on a thin layer of gate oxide 128 above a silicon substrate 130.
• This arrangement of layers of a wafer illustrates an intermediate step in the fabrication of many different devices.
• the intermediate step could be a step in the fabrication of a memory device, a logic device or an eDRAM.
• the method of etching is essentially the same as that described previously with reference to figures 2 and 1 except that a different etching chemistry is used during the main etch step for the polysilicon layer 126.
• the etchant gas composition comprises CF 4 , chlorine, HBr, oxygen and helium.
• the etching chemistry for polysilicon is well know to persons of ordinary skill in the art and need not be described further.
• Figure 4 shows a flow chart illustrating a further embodiment of the method 300 for etching a feature while using HBr to cure the 193nm photoresist material. The method begins 310 with introducing HBr into a plasma processing device 312.
• the HBr acts as a source of Br species in the plasma, which is active to cure the photoresist material 122.
• An etchant gas mixture is also introduced 314 into the plasma processing chamber at the same time as the HBr.
• the composition of the etchant gas will depend on the wafer layer being etched, but will include at least one source of etchant species, such as fluorine species when CF 4 or other fluorocarbons are used as the etchant gas. In other embodiments of the invention, hydro fluorocarbons can be used as the source of etchant species.
• a high density plasma is then struck and sustained 316 by operating the plasma processing device under low pressure, and high power conditions.
• the bromine species present in the plasma is active to cure the photoresist material while the fluorine species is active as an etchant to etch away layers of the wafer below the photoresist layer.
• the etch of the feature can be carried out 318 and the hardening of the photoresist feature prevents its deformation and helps to ensure the propagation of a well defined featured into the wafer.
• the etch method terminates 320 once the desired end point is reached.
• Figure 6 A shows an electron microscope picture of a cross section 601 through a wafer like that shown in figure 1 after a SiN hardmask layer etch with the addition of HBr.
• Figure 6B shows a perspective view along etched trenches 602 and figure 6C shows the resulting etch profile 603 for the SiN layer.
• the addition of HBr to cure the 193nm photoresist material results in a significant amount of the photoresist layer material 604 being present after completion of the hardmask etch.
• figure 6B shows there is a significant absence of any twisting of the photoresist material and well defined, straight lines are etched. There is some tapering of the profile of the SiN layer 606, as shown in figure 6C.
• This method does not provide as good a SiN layer etch profile as the first method 200 described, but is still obviates photoresist deformation and collapse.
• the invention has been described above in connection with 193nm photoresist materials, but the invention can also be used with other deep Ultra Violet (DUV) photoresist materials, including 248nm.
• DUV deep Ultra Violet
• Other steps can be added to the method of the invention as required in order to fabricate a particular device. However, the step of curing the photoresist material should be either before etching the feature in the underlying layer or concomitant with etching the feature in the underlying layer.

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• Engineering & Computer Science (AREA)
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• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Drying Of Semiconductors (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)

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• 2002
  • 2002-08-14 US US10/219,995 patent/US6923920B2/en not_active Expired - Lifetime
• 2003
  • 2003-07-31 CN CNB038191784A patent/CN100423191C/zh not_active Expired - Fee Related
  • 2003-07-31 JP JP2004529231A patent/JP2005535936A/ja active Pending
  • 2003-07-31 EP EP03788310A patent/EP1529308A1/en not_active Withdrawn
  • 2003-07-31 WO PCT/US2003/024137 patent/WO2004017390A1/en not_active Ceased
  • 2003-07-31 KR KR1020057002028A patent/KR100990064B1/ko not_active Expired - Fee Related
  • 2003-07-31 AU AU2003257999A patent/AU2003257999A1/en not_active Abandoned
  • 2003-08-07 TW TW092121695A patent/TWI307121B/zh not_active IP Right Cessation
• 2005
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