US20020076895A1 - Fabrication method for an embedded dynamic random access memory (DRAM) - Google Patents
Fabrication method for an embedded dynamic random access memory (DRAM) Download PDFInfo
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- US20020076895A1 US20020076895A1 US09/799,909 US79990901A US2002076895A1 US 20020076895 A1 US20020076895 A1 US 20020076895A1 US 79990901 A US79990901 A US 79990901A US 2002076895 A1 US2002076895 A1 US 2002076895A1
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- 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
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
- H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
- H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System
- H01L21/28518—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System the conductive layers comprising silicides
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- 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
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/09—Manufacture or treatment with simultaneous manufacture of the peripheral circuit region and memory cells
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/31—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells having a storage electrode stacked over the transistor
- H10B12/315—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells having a storage electrode stacked over the transistor with the capacitor higher than a bit line
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/48—Data lines or contacts therefor
- H10B12/485—Bit line contacts
Definitions
- the present invention relates to a fabrication method for a memory device. More particularly, the present invention relates to a fabrication method for an embedded direct random access memory (DRAM).
- DRAM embedded direct random access memory
- Embedded dynamic random access memory are integrated devices that integrate a memory cell array and logic circuit array on a single wafer. Embedded DRAM can store large amounts of information at very high speeds and are of great benefit to the use of the integrated circuit. Often Embedded DRAM is applied to a logic circuit that processes large amounts of data, such as a graphic processor.
- a complete embedded DRAM comprises a logic circuit, a transfer field effect transistor (FET), and a capacitor coupled to a transfer field effect transistor. The transfer FET controls the connection between the capacitor's bottom electrode and the bit line. Thus, information can either be read from the capacitor or stored in the capacitor.
- FET transfer field effect transistor
- FIGS. 1 A- 1 F are schematic drawings illustrating the conventional method of fabricating an embedded DRAM.
- a substrate is provided.
- a (metal oxide semiconductor) MOS transistor 110 is then formed above the P-type MOS region 106 and N-type MOS region 108 of the memory cell region 102 and the periphery circuit region 104 of the substrate 100 .
- a barrier layer 111 is formed over the substrate 100 in order to cover a predetermined area where a self-aligned silicide is not formed.
- a dielectric layer 112 is formed over the substrate 100 .
- a landing pad 114 is then formed in the dielectric layer 112 of the memory cell region 102 of the substrate 100 (as shown in FIG. 1B).
- a dielectric layer 116 is formed over the substrate 100 , while a photoresist layer 123 is formed on the dielectric layer 116 .
- an etching step is performed to form a contact opening 118 in the dielectric layer 116 from the memory cell region 102 .
- contact openings 120 , 122 are formed in the dielectric layers 112 , 116 from the PMOS region 106 and NMOS region 108 of the peripheral circuit region 104 , respectively.
- the photoresist 123 is removed.
- N-type ions and P-type ions would then be implanted into the NMOS region 106 and PMOS region 108 of the peripheral circuit region 104 before the contact openings 120 , 122 are filled with a tungsten layer for forming contact windows, in order to reduce the current leakage from subsequently formed salicide region (source/drain region) on the substrate 100 .
- the contact openings 120 , 122 are formed simultaneously in the photolithographic and etching process for forming the bit line contact opening 118 .
- a photoresist 128 is formed on the dielectric layer 116 for covering the contact openings 118 , 122 before a P-type ion implantation is performed on the MOS device exposed in the contact opening 120 .
- the contact openings 118 , 120 , 122 are filled with a tungsten layer, so that a contact window 132 connecting to the memory cell region 102 is formed together with contact windows 134 , 136 connecting respectively to the PMOS region 106 and NMOS region 108 .
- a bit line 138 is formed over the memory cell region 102 of the substrate 100 , while forming a first metal layer 140 , 142 over the peripheral circuit region 104 , before any subsequent steps for fabricating the capacitor are performed.
- P-type and N-type ion implantation processes are typically conducted in the MOS device exposed by contact openings 120 and 122 , before the contact openings are filled with a tungsten layer.
- contact openings 120 and 122 are formed by the same photoligthographic etching process in which the bit-line contact 118 is formed.
- an additional photoresist layer must be formed over the MOS exposed by the contact opening 122 , during the implantation of N-type ions or over the MOS exposed by the contact opening 120 during the implantation of P-type ions.
- the photoresist layers 124 and 128 are formed to make sure that the ions are only implanted into the contact opening 122 or the contact opening 120 . Accordingly, the conventional fabrication process requires the additional cost of two masks and increases, as a consequence, the number of fabrication steps, which also affects yield.
- the invention provides a fabrication method for an embedded dynamic random access memory.
- a dielectric layer is formed over the substrate.
- a bit-line contact opening that exposes the landing pad, and a contact opening that exposes the N-type MOS in the periphery circuit region is formed in the dielectric layer.
- An N-type ion implantation step is performed to implant N-type ions into the landing pad and N-type MOS.
- the first bit-line contact opening and the first contact opening are filled with a conductive layer to form a bit-line contact and first contact.
- a bit-line electrically connected to the bit-line contact is formed.
- Another dielectric layer is formed over the substrate.
- a storage node contact opening that exposes another landing pad and a second contact opening that exposes a P-type MOS in the periphery circuit region are formed.
- a P-type ion implantation is performed to implant P-type ions into the landing pad and the P-type MOS exposed by the second contact opening.
- the storage node contact opening and the second contact opening are filled with a conductive layer, to form a storage node contact and a second contact.
- a capacitor that is electrically connected to the storage node contact is then formed.
- a bit-line contact opening is formed as the contact opening exposing the N-type MOS in the periphery circuit region is formed.
- a contact opening that exposes the P-type MOS in the periphery circuit region is not formed.
- a second contact opening that exposes the P-type MOS in the periphery circuit region is formed as the storage node contact is formed.
- present invention provides an embedded dynamic random access memory (DRAM) that reduces current leakage in the area where a self-aligned silicide is not formed
- DRAM embedded dynamic random access memory
- FIGS. 1 A- 1 F are schematic drawings illustrating the process of fabricating a conventional embedded DRAM.
- FIGS. 2 A- 2 F are schematic drawings illustrating the process of fabricating an embedded DRAM according to a preferred embodiment of this invention.
- a substrate 200 is provided.
- the substrate 200 is divided into a memory cell region 202 and a periphery circuit region 204 , wherein the periphery circuit region 204 includes a PMOS region 206 and an NMOS region 208 .
- a memory cell well 210 On the substrate 200 a memory cell well 210 , an N-type well 212 and a P-type well 214 are formed.
- the approximate doping concentration of the N-type well 212 and the P-type well 214 is about between 1 ⁇ 10 16 cm 3 and 1 ⁇ 10 17 cm 3 .
- the doping concentration of the memory cell well 210 is lower than that of the N-type well 212 and P-type well 214 .
- An isolation region 216 is then formed on the substrate 200 .
- the isolation region 216 can be a trench formed in the substrate 200 by a shallow trench isolation layer (STI) method that has been refilled with an insulation layer.
- STI shallow trench isolation layer
- MOS transistor 218 is then formed in the memory cell region 202 and above the PMOS and NMOS regions of the periphery circuit region 204 .
- MOS transistor 218 includes a gate 220 and a source/drain region 222 .
- the gate 220 further includes a gate oxide layer 224 , a polysilicon layer 226 , a silicide layer 228 , a cap layer 230 and a spacer 232 .
- the method of forming the gate oxide layer 220 can include thermal oxidation.
- the method of forming the polysilicon layer 222 can include low-pressure chemical vapor deposition (LPCVD).
- the polysilicon layer 222 can be doped with ions to provide conductivity.
- the material of the silicide layer 228 can include tungsten silicide.
- the method for forming the silicide layer 228 can include physical vapor deposition (PVD) or chemical vapor deposition (CVD).
- the material of the cap layer 230 can include silicon nitride and the method for forming the cap layer 230 can include chemical vapor deposition (CVD).
- the material of the spacer 232 can include silicon nitride and the method for forming the spacer 232 can include the following procedure: A silicon nitride layer is formed over the substrate 200 by low pressure chemical vapor deposition (LPCVD).
- LPCVD low pressure chemical vapor deposition
- etch back step is then conducted to form a spacer from the remaining portion of silicon nitride on a sidewall of the patterned gate oxide layer 224 , the polysilicon layer 226 , the silicide layer 228 and the cap layer 230 .
- MOS transistor 218 formed in the PMOS region 206 of the memory cell 202 and the periphery circuit 204 as well as above the NMOS region 208 are labeled as 218 a , 218 b and 218 c , respectively.
- gate 220 is labeled as 220 a , 220 b and 220 c
- source/drain region 220 is labeled as 222 a , 222 b and 222 c respectively.
- a barrier layer 234 is formed over the substrate 200 before conducting a self-aligned silicide fabrication process.
- the purpose of this step is to cover the area on the substrate 200 where the self-aligned silicide is not formed (i.e. the memory cell region 202 and periphery circuit region 204 of FIG. 2A).
- the material of the barrier layer 234 can include silicon nitride and the method of formation can include low-pressure chemical vapor deposition (LPCVD).
- LPCVD low-pressure chemical vapor deposition
- a self-aligned silicide fabrication process is then conducted to form a self-aligned silicide above the area that has not been covered by the barrier layer (not shown).
- a dielectric layer 236 is then formed over the substrate 200 .
- the material of the dielectric layer 236 can include silicon oxide and the method of formation can include a chemical vapor deposition (CVD).
- photoligthograpy and etching are performed to partially remove the dielectric layer 236 and the barrier layer of the memory cell region 202 to form self aligned contact openings 238 and 240 that expose the source/drain region 222 a .
- the self-aligned contact openings 238 a and 240 a are then filled with a conductive layer, to form landing pads 238 and 240 .
- the material of the conductive layer can include polysilicon that is doped to provide conductivity.
- the preferred method in forming the landing pads 238 and 240 includes low-pressure chemical vapor depositing polysilicon in the self-aligned contact openings 238 a , 240 a and above the dielectric layer 236 , followed by peforming an etch back method or chemical mechanical polishing method to remove the polysilicon layer above the dielectric layer 236 .
- the polysilicon layer can be doped in-situ, in order to provide conductivity. The approximate doping concentration is between 1 ⁇ 1020/cm 3 and 2 ⁇ 1020/cm 3 .
- a dielectric layer 242 is then formed over the substrate 200 .
- the material of the dielectric layer 242 can include silicon oxide.
- the method of formation can include chemical vapor deposition. Photolithography and etching are conducted to form a bit-line contact opening 244 in the dielectric layer 242 of memory cell region 202 that exposes the landing pad 238 .
- a contact opening 246 is formed in dielectric layers 242 and 236 and the barrier layer 234 above the NMOS region 208 , that exposes the NMOS 218 c .
- the contact opening 246 exposes the NMOS 218 c formed above the NMOS region 208 and the source/drain region 222 c , where self-aligned silicide is not formed.
- the region exposed by the contact opening 246 can include a gate or source/region where there is self-aligned silicide or where there is no self-aligned silicide.
- the region exposed by the contact opening 246 is not limited to what is depicted in FIG. 2C.
- An ion implantation step 248 is conducted to implant N-type ions into the landing pad 238 and N-type MOS 218 , to lower the current leakage of the region where self-aligned silicide is not formed (i.e. the source/drain region) above the NMOS region, without the need for an additional photomask.
- the dopant of the N-type ion implantation step 248 can include phosphorus or arsenic with a doping concentration between 3 ⁇ 10 14 /cm 3 and 1 ⁇ 10 18 /cm 3 .
- bit-line contact opening 244 and the contact opening 246 are filled with a conductive layer, to form a bit-line contact 250 electrically connected to the landing pad 238 and to form a contact 252 electrically connected to the NMOS 218 c of NMOS region 208 .
- the material of the conductive layer can include tungsten and the method of fabrication can include a chemical vapor deposition step to deposit a tungsten layer in both the bit-line contact opening 244 and the contact opening 246 , as well as above the dielectric layer 242 . Afterwards, an etch back step or chemical mechanical polishing step is performed to remove the tungsten metal layer above the dielectric layer 242 . The tungsten-filled bit-line contact opening 242 and contact opening 246 , form bit-line contact 250 and contact 252 .
- the dielectric layer 258 can be a multi-layered structure comprising alternating layers of silicon oxide and spin-on glass (SOG).
- a storage node contact opening 260 that exposes the landing pad 240 , in the dielectric layer 258 and 254 of the memory cell 202 .
- a contact opening 262 that exposes the PMOS 218 b is formed in the dielectric layer 258 , 254 and 236 as well the barrier layer 234 of the PMOS region 206 .
- the contact opening 262 shown in FIG. 2E, exposes the source/drain region 222 b of the P-type MOS 218 b above the PMOS region 206 , where self-aligned silicide has not been formed, and the silicide layer 228 of the gate 220 b .
- the region exposed by the contact opening can actually include the gate or source/drain region where there is self-aligned silicide or where there is no self-aligned silicide.
- the region exposed by the contact opening 262 is not limited to what is depicted in FIG. 2E.
- a P-type ion implantation step 264 is conducted to implant P-type ions into the PMOS transistor 218 b exposed by the contact opening 262 , to lower the current leakage of the unformed self-aligned silicide region (i.e. the source/drain region) above the PMOS region 206 .
- the dopant of the P-type ion implantation step 264 can include boron with a concentration between 3 ⁇ 10 14 /cm 3 and 1 ⁇ 10 18 /cm 3 .
- P-type ions are also implanted into the landing pad 240 exposed by the storage node contact opening 260 .
- the doping concentration of the P-type ions in the P-type implantation step 264 is approximately one percent the concentration of the N-type ions in the landing pad 240 .
- the P-type ions of the P-type ion implantation step 264 only offset one percent of the N-type ions in the landing pad 240 and thus has very little impact on the resistivity of the landing pad 240 .
- the storage node contact opening 260 and the contact opening 262 are filled with a conductive layer, to form a storage node contact 266 and contact 268 .
- the material of the conductive layer can be tungsten, for example.
- the method of formation can include a chemical vapor deposition step to deposit a layer of tungsten metal in the storage node contact opening 260 and the contact opening 262 , as well as above the dielectric layer 258 . Afterwards, an etch back procedure or chemical mechanical polishing step is conducted to remove the tungsten metal above the dielectric layer 258 , which results in storage node contact 266 and contact 268 .
- a capacitor 270 is formed to electrically connected to the source/drain region 222 a through storage node contact 266 and landing pad 240 , and the inner metal layer 272 is formed in the peripheral circuit region 204 .
- the bit-line contact is formed at the same time as the contact opening that exposes the NMOS in the periphery circuit region.
- the contact opening that exposes the PMOS in the periphery circuit region is not formed at this time.
- the second contact opening that exposes the PMOS in the periphery circuit region is instead formed as the storage node contact opening is formed.
- the present invention can lower the current leakage of the unformed self-aligned silicide region.
- the method of the present invention can also reduce the number of masks used, which in turn lowers fabrication costs.
- the method of the present invention can reduce the number of fabrication steps, which increases yield.
Abstract
Description
- This application claims the priority benefit of Taiwan application serial no. 89127057, filed Dec. 18, 2000.
- 1. Field of the Invention
- The present invention relates to a fabrication method for a memory device. More particularly, the present invention relates to a fabrication method for an embedded direct random access memory (DRAM).
- 2. Description of the Related Art
- Embedded dynamic random access memory (DRAM) are integrated devices that integrate a memory cell array and logic circuit array on a single wafer. Embedded DRAM can store large amounts of information at very high speeds and are of great benefit to the use of the integrated circuit. Often Embedded DRAM is applied to a logic circuit that processes large amounts of data, such as a graphic processor. A complete embedded DRAM comprises a logic circuit, a transfer field effect transistor (FET), and a capacitor coupled to a transfer field effect transistor. The transfer FET controls the connection between the capacitor's bottom electrode and the bit line. Thus, information can either be read from the capacitor or stored in the capacitor.
- FIGS.1A-1F are schematic drawings illustrating the conventional method of fabricating an embedded DRAM. As shown in FIG. 1A, a substrate is provided. A (metal oxide semiconductor)
MOS transistor 110 is then formed above the P-type MOS region 106 and N-type MOS region 108 of thememory cell region 102 and theperiphery circuit region 104 of thesubstrate 100. Afterwards, abarrier layer 111 is formed over thesubstrate 100 in order to cover a predetermined area where a self-aligned silicide is not formed. After conducting a self-aligned silicide fabrication process, adielectric layer 112 is formed over thesubstrate 100. Alanding pad 114 is then formed in thedielectric layer 112 of thememory cell region 102 of the substrate 100 (as shown in FIG. 1B). - Referring to FIG. 1C, a
dielectric layer 116 is formed over thesubstrate 100, while aphotoresist layer 123 is formed on thedielectric layer 116. With the photoresist serving as a mask, an etching step is performed to form a contact opening 118 in thedielectric layer 116 from thememory cell region 102. Simultaneously,contact openings dielectric layers PMOS region 106 andNMOS region 108 of theperipheral circuit region 104, respectively. - Referring to FIGS. 1D and 1E, the
photoresist 123 is removed. Conventionally, N-type ions and P-type ions would then be implanted into theNMOS region 106 andPMOS region 108 of theperipheral circuit region 104 before thecontact openings substrate 100. However, thecontact openings line contact opening 118. So, when the MOS devices exposed in thecontact openings contact openings contact openings photoresist 124 on thedielectric layer 116 for covering thecontact openings contact opening 122. As shown in FIG. 1E, thephotoresist 124 is removed. After that, aphotoresist 128 is formed on thedielectric layer 116 for covering thecontact openings contact opening 120. Next, referring to FIG. 1F, thecontact openings contact window 132 connecting to thememory cell region 102 is formed together withcontact windows PMOS region 106 andNMOS region 108. Then, abit line 138 is formed over thememory cell region 102 of thesubstrate 100, while forming afirst metal layer peripheral circuit region 104, before any subsequent steps for fabricating the capacitor are performed. - In order to reduce the current leakage in the region where a self aligned silicide is not formed (i.e. the source/drain region), P-type and N-type ion implantation processes are typically conducted in the MOS device exposed by
contact openings contact openings line contact 118 is formed. Thus, an additional photoresist layer must be formed over the MOS exposed by thecontact opening 122, during the implantation of N-type ions or over the MOS exposed by thecontact opening 120 during the implantation of P-type ions. Thephotoresist layers - The invention provides a fabrication method for an embedded dynamic random access memory. In this method, after several landing pads are formed on the substrate, a dielectric layer is formed over the substrate. A bit-line contact opening that exposes the landing pad, and a contact opening that exposes the N-type MOS in the periphery circuit region is formed in the dielectric layer. An N-type ion implantation step is performed to implant N-type ions into the landing pad and N-type MOS. Afterwards, the first bit-line contact opening and the first contact opening are filled with a conductive layer to form a bit-line contact and first contact. A bit-line electrically connected to the bit-line contact is formed. Another dielectric layer is formed over the substrate. In the aforementioned dielectric layer, a storage node contact opening that exposes another landing pad and a second contact opening that exposes a P-type MOS in the periphery circuit region are formed. A P-type ion implantation is performed to implant P-type ions into the landing pad and the P-type MOS exposed by the second contact opening. The storage node contact opening and the second contact opening are filled with a conductive layer, to form a storage node contact and a second contact. A capacitor that is electrically connected to the storage node contact is then formed.
- In the method of the present invention a bit-line contact opening is formed as the contact opening exposing the N-type MOS in the periphery circuit region is formed. However, a contact opening that exposes the P-type MOS in the periphery circuit region is not formed. Rather, a second contact opening that exposes the P-type MOS in the periphery circuit region is formed as the storage node contact is formed. Thus, following the formation of the bit-line contact and the storage node contact, an N-type and P-type ion implantation can be performed, to implant both N-type or P-type ions into the substrate without having to form an additional photoresist layer. As a result, the reduction of current leakage in the area where a self-aligned silicide is not formed can be attained through the implantation process.
- Accordingly, through the present invention the number of photoresists used can be reduced. Moreover, the number of fabrication steps as well as fabrication cost can be reduced, resulting in an increased of the yield. Additionally, present invention provides an embedded dynamic random access memory (DRAM) that reduces current leakage in the area where a self-aligned silicide is not formed
- It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
- The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention, and, together with the description, serve to explain the principles of the invention. In the drawings,
- FIGS.1A-1F are schematic drawings illustrating the process of fabricating a conventional embedded DRAM; and
- FIGS.2A-2F are schematic drawings illustrating the process of fabricating an embedded DRAM according to a preferred embodiment of this invention.
- As shown in FIG. 2A, a
substrate 200 is provided. Thesubstrate 200 is divided into amemory cell region 202 and aperiphery circuit region 204, wherein theperiphery circuit region 204 includes aPMOS region 206 and anNMOS region 208. On the substrate 200 a memory cell well 210, an N-type well 212 and a P-type well 214 are formed. The approximate doping concentration of the N-type well 212 and the P-type well 214 is about between 1×1016 cm3 and 1×1017 cm3. The doping concentration of the memory cell well 210 is lower than that of the N-type well 212 and P-type well 214. Anisolation region 216 is then formed on thesubstrate 200. Theisolation region 216 can be a trench formed in thesubstrate 200 by a shallow trench isolation layer (STI) method that has been refilled with an insulation layer. - As shown in FIG. 2A, a
MOS transistor 218 is then formed in thememory cell region 202 and above the PMOS and NMOS regions of theperiphery circuit region 204.MOS transistor 218 includes agate 220 and a source/drain region 222. Thegate 220 further includes agate oxide layer 224, apolysilicon layer 226, asilicide layer 228, acap layer 230 and aspacer 232. The method of forming thegate oxide layer 220 can include thermal oxidation. The method of forming thepolysilicon layer 222 can include low-pressure chemical vapor deposition (LPCVD). Thepolysilicon layer 222 can be doped with ions to provide conductivity. The material of thesilicide layer 228 can include tungsten silicide. The method for forming thesilicide layer 228 can include physical vapor deposition (PVD) or chemical vapor deposition (CVD). The material of thecap layer 230 can include silicon nitride and the method for forming thecap layer 230 can include chemical vapor deposition (CVD). The material of thespacer 232 can include silicon nitride and the method for forming thespacer 232 can include the following procedure: A silicon nitride layer is formed over thesubstrate 200 by low pressure chemical vapor deposition (LPCVD). An etch back step is then conducted to form a spacer from the remaining portion of silicon nitride on a sidewall of the patternedgate oxide layer 224, thepolysilicon layer 226, thesilicide layer 228 and thecap layer 230. For the sake of clarity, theMOS transistor 218 formed in thePMOS region 206 of thememory cell 202 and theperiphery circuit 204 as well as above theNMOS region 208 are labeled as 218 a, 218 b and 218 c, respectively. Similarly,gate 220 is labeled as 220 a, 220 b and 220 c, and source/drain region 220 is labeled as 222 a, 222 b and 222 c respectively. - As shown in FIG. 2A, a
barrier layer 234 is formed over thesubstrate 200 before conducting a self-aligned silicide fabrication process. The purpose of this step is to cover the area on thesubstrate 200 where the self-aligned silicide is not formed (i.e. thememory cell region 202 andperiphery circuit region 204 of FIG. 2A). The material of thebarrier layer 234 can include silicon nitride and the method of formation can include low-pressure chemical vapor deposition (LPCVD). A self-aligned silicide fabrication process is then conducted to form a self-aligned silicide above the area that has not been covered by the barrier layer (not shown). Adielectric layer 236 is then formed over thesubstrate 200. The material of thedielectric layer 236 can include silicon oxide and the method of formation can include a chemical vapor deposition (CVD). - As shown in FIG. 2B, photoligthograpy and etching are performed to partially remove the
dielectric layer 236 and the barrier layer of thememory cell region 202 to form self alignedcontact openings drain region 222 a. The self-alignedcontact openings pads landing pads contact openings dielectric layer 236, followed by peforming an etch back method or chemical mechanical polishing method to remove the polysilicon layer above thedielectric layer 236. The polysilicon layer can be doped in-situ, in order to provide conductivity. The approximate doping concentration is between 1×1020/cm3 and 2×1020/cm 3. - As shown in2C, a
dielectric layer 242 is then formed over thesubstrate 200. The material of thedielectric layer 242 can include silicon oxide. The method of formation can include chemical vapor deposition. Photolithography and etching are conducted to form a bit-line contact opening 244 in thedielectric layer 242 ofmemory cell region 202 that exposes thelanding pad 238. Moreover, acontact opening 246 is formed indielectric layers barrier layer 234 above theNMOS region 208, that exposes theNMOS 218 c. Thecontact opening 246 in FIG. 2C exposes theNMOS 218 c formed above theNMOS region 208 and the source/drain region 222 c, where self-aligned silicide is not formed. However, the region exposed by thecontact opening 246 can include a gate or source/region where there is self-aligned silicide or where there is no self-aligned silicide. The region exposed by thecontact opening 246 is not limited to what is depicted in FIG. 2C. - An
ion implantation step 248 is conducted to implant N-type ions into thelanding pad 238 and N-type MOS 218, to lower the current leakage of the region where self-aligned silicide is not formed (i.e. the source/drain region) above the NMOS region, without the need for an additional photomask. The dopant of the N-typeion implantation step 248 can include phosphorus or arsenic with a doping concentration between 3×1014/cm3 and 1×1018/cm3. - As shown in FIG. 2D, the bit-
line contact opening 244 and thecontact opening 246 are filled with a conductive layer, to form a bit-line contact 250 electrically connected to thelanding pad 238 and to form acontact 252 electrically connected to theNMOS 218 c ofNMOS region 208. - The material of the conductive layer can include tungsten and the method of fabrication can include a chemical vapor deposition step to deposit a tungsten layer in both the bit-
line contact opening 244 and thecontact opening 246, as well as above thedielectric layer 242. Afterwards, an etch back step or chemical mechanical polishing step is performed to remove the tungsten metal layer above thedielectric layer 242. The tungsten-filled bit-line contact opening 242 andcontact opening 246, form bit-line contact 250 and contact 252. - As shown in FIG. 2D, photolithography and etching are conducted to form above the dielectric layer254 a bit-
line 254 that is electrically connected to the bit-line contact 250 and to form ametal layer 256 that is electrically connected to thecontact opening 252. Anotherdielectric layer 258 is then formed over thesubstrate 200. Thedielectric layer 258 can be a multi-layered structure comprising alternating layers of silicon oxide and spin-on glass (SOG). - As shown in FIG. 2E, photolithography and etching are conducted to form a storage
node contact opening 260 that exposes thelanding pad 240, in thedielectric layer memory cell 202. In addition, acontact opening 262 that exposes thePMOS 218 b is formed in thedielectric layer barrier layer 234 of thePMOS region 206. Thecontact opening 262, shown in FIG. 2E, exposes the source/drain region 222 b of the P-type MOS 218 b above thePMOS region 206, where self-aligned silicide has not been formed, and thesilicide layer 228 of thegate 220 b. However, the region exposed by the contact opening can actually include the gate or source/drain region where there is self-aligned silicide or where there is no self-aligned silicide. The region exposed by thecontact opening 262, is not limited to what is depicted in FIG. 2E. - Without the need for an additional photomask, a P-type
ion implantation step 264 is conducted to implant P-type ions into thePMOS transistor 218 b exposed by thecontact opening 262, to lower the current leakage of the unformed self-aligned silicide region (i.e. the source/drain region) above thePMOS region 206. The dopant of the P-typeion implantation step 264 can include boron with a concentration between 3×1014/cm3 and 1×1018/cm3. During the ion implantation step, P-type ions are also implanted into thelanding pad 240 exposed by the storagenode contact opening 260. However, the doping concentration of the P-type ions in the P-type implantation step 264 is approximately one percent the concentration of the N-type ions in thelanding pad 240. Thus, the P-type ions of the P-typeion implantation step 264 only offset one percent of the N-type ions in thelanding pad 240 and thus has very little impact on the resistivity of thelanding pad 240. - As shown in FIG. 2F, the storage
node contact opening 260 and thecontact opening 262 are filled with a conductive layer, to form astorage node contact 266 and contact 268. The material of the conductive layer can be tungsten, for example. The method of formation can include a chemical vapor deposition step to deposit a layer of tungsten metal in the storagenode contact opening 260 and thecontact opening 262, as well as above thedielectric layer 258. Afterwards, an etch back procedure or chemical mechanical polishing step is conducted to remove the tungsten metal above thedielectric layer 258, which results instorage node contact 266 and contact 268. After thestorage node contact 266 has been formed, acapacitor 270 is formed to electrically connected to the source/drain region 222 a throughstorage node contact 266 andlanding pad 240, and theinner metal layer 272 is formed in theperipheral circuit region 204. - In the method of the present invention, the bit-line contact is formed at the same time as the contact opening that exposes the NMOS in the periphery circuit region. The contact opening that exposes the PMOS in the periphery circuit region, however, is not formed at this time. The second contact opening that exposes the PMOS in the periphery circuit region is instead formed as the storage node contact opening is formed. Thus, after the bit-line contact opening and the storage node contact opening have been formed, the N-type and P-type ion implantation steps can be performed directly after to implant N-type ions or P-type ions into the substrate. The ion implantation step, in the method of present invention, attains the goal of lowering the current leakage of the unformed self-aligned silicide region, without the necessity of having to form an additional photoresist.
- Accordingly, the present invention can lower the current leakage of the unformed self-aligned silicide region. The method of the present invention can also reduce the number of masks used, which in turn lowers fabrication costs. Moreover, the method of the present invention can reduce the number of fabrication steps, which increases yield.
- It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Claims (16)
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TW89127057 | 2000-12-18 | ||
TW089127057 | 2000-12-18 | ||
TW089127057A TW487910B (en) | 2000-12-18 | 2000-12-18 | Manufacturing method of embedded DRAM |
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US6406971B1 US6406971B1 (en) | 2002-06-18 |
US20020076895A1 true US20020076895A1 (en) | 2002-06-20 |
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US09/799,909 Expired - Fee Related US6406971B1 (en) | 2000-12-18 | 2001-03-06 | Fabrication method for an embedded dynamic random access memory (DRAM) |
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TW (1) | TW487910B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US20040127013A1 (en) * | 2002-12-31 | 2004-07-01 | Nanya Technology Corporation | Method for forming bit line |
US20060281291A1 (en) * | 2005-06-08 | 2006-12-14 | Atmel Germany Gmbh | Method for manufacturing a metal-semiconductor contact in semiconductor components |
EP1732123A3 (en) * | 2005-06-08 | 2007-01-03 | ATMEL Germany GmbH | Method of fabricating a metal-semiconductor contact in semiconductor devices |
US9245791B2 (en) * | 2011-04-15 | 2016-01-26 | Globalfoundries Inc. | Method for fabricating a contact |
Families Citing this family (10)
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KR100446293B1 (en) * | 2002-01-07 | 2004-09-01 | 삼성전자주식회사 | Manufacturing method for semiconductor device including register |
US6551877B1 (en) * | 2002-06-11 | 2003-04-22 | Powerchip Semiconductor Corp. | Method of manufacturing memory device |
KR100480601B1 (en) * | 2002-06-21 | 2005-04-06 | 삼성전자주식회사 | Semiconductor memory device and manufacturing method thereof |
KR100504693B1 (en) * | 2003-02-10 | 2005-08-03 | 삼성전자주식회사 | Ferroelectric memory device and method for fabricating the same |
TWI355042B (en) * | 2007-04-27 | 2011-12-21 | Nanya Technology Corp | Method for forming bit-line contact plug and trans |
TWI375300B (en) * | 2008-07-22 | 2012-10-21 | Nanya Technology Corp | Dynamic random access memory structure and method of making the same |
JP5638408B2 (en) * | 2011-01-28 | 2014-12-10 | ルネサスエレクトロニクス株式会社 | Semiconductor device and manufacturing method of semiconductor device |
TWI447857B (en) | 2011-08-22 | 2014-08-01 | Inotera Memories Inc | Fabricating method of dram structrue |
TWI462275B (en) | 2011-11-14 | 2014-11-21 | Inotera Memories Inc | Memory layout structure and memory structure |
US9136321B1 (en) | 2014-04-30 | 2015-09-15 | International Business Machines Corporation | Low energy ion implantation of a junction butting region |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6080620A (en) * | 1998-06-03 | 2000-06-27 | Vanguard International Semiconductor Corporation | Method for fabricating interconnection and capacitors of a DRAM using a simple geometry active area, self-aligned etching, and polysilicon plugs |
US6096595A (en) * | 1999-05-12 | 2000-08-01 | Taiwan Semiconductor Manufacturing Company | Integration of a salicide process for MOS logic devices, and a self-aligned contact process for MOS memory devices |
US6350646B1 (en) * | 2000-01-18 | 2002-02-26 | United Microelectronics Corp. | Method for reducing thermal budget in node contact application |
-
2000
- 2000-12-18 TW TW089127057A patent/TW487910B/en not_active IP Right Cessation
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2001
- 2001-03-06 US US09/799,909 patent/US6406971B1/en not_active Expired - Fee Related
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040127013A1 (en) * | 2002-12-31 | 2004-07-01 | Nanya Technology Corporation | Method for forming bit line |
US7052949B2 (en) * | 2002-12-31 | 2006-05-30 | Nanya Technology Corporation | Method for forming bit line |
US20060281291A1 (en) * | 2005-06-08 | 2006-12-14 | Atmel Germany Gmbh | Method for manufacturing a metal-semiconductor contact in semiconductor components |
EP1732123A3 (en) * | 2005-06-08 | 2007-01-03 | ATMEL Germany GmbH | Method of fabricating a metal-semiconductor contact in semiconductor devices |
US7923362B2 (en) | 2005-06-08 | 2011-04-12 | Telefunken Semiconductors Gmbh & Co. Kg | Method for manufacturing a metal-semiconductor contact in semiconductor components |
US9245791B2 (en) * | 2011-04-15 | 2016-01-26 | Globalfoundries Inc. | Method for fabricating a contact |
US9343354B2 (en) | 2011-04-15 | 2016-05-17 | Globalfoundries Inc. | Middle of line structures and methods for fabrication |
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US6406971B1 (en) | 2002-06-18 |
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