WO2000019528A9 - Dram-zellenanordnung und verfahren zu deren herstellung - Google Patents
Dram-zellenanordnung und verfahren zu deren herstellungInfo
- Publication number
- WO2000019528A9 WO2000019528A9 PCT/DE1999/002939 DE9902939W WO0019528A9 WO 2000019528 A9 WO2000019528 A9 WO 2000019528A9 DE 9902939 W DE9902939 W DE 9902939W WO 0019528 A9 WO0019528 A9 WO 0019528A9
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- parts
- produced
- depressions
- structures
- word lines
- Prior art date
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Classifications
-
- 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
-
- 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
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/03—Making the capacitor or connections thereto
- H10B12/038—Making the capacitor or connections thereto the capacitor being in a trench in the substrate
- H10B12/0383—Making the capacitor or connections thereto the capacitor being in a trench in the substrate wherein the transistor is vertical
-
- 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
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/05—Making the transistor
- H10B12/053—Making the transistor the transistor being at least partially in a trench in the substrate
-
- 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
- H10B12/39—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells the capacitor and the transistor being in a same trench
- H10B12/395—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells the capacitor and the transistor being in a same trench the transistor being vertical
Definitions
- the invention relates to a DRAM cell arrangement and a method for the production thereof.
- the general aim is to produce a DRAM cell arrangement with an ever higher packing density.
- the problem arises of producing the storage capacitor on a small area but nevertheless providing it with a sufficiently high capacitance so that the signal of the charge when Reading the information does not get lost in background noise.
- a minimum capacitance of the storage capacitor required for reading the information is smaller than in a DRAM cell arrangement with so-called open bit lines, ie without folded bit lines.
- a word line that drives the memory cell to be read must not have any memory cell be connected, which is connected to the adjacent bit line, so that the signal of the adjacent bit line consists only of background noise.
- a memory cell comprises a transistor and a storage capacitor which are arranged next to one another.
- a first word line and a second word line are arranged above the memory cell.
- Memory cells adjacent to one another along the word lines are alternately connected to the first word line and the second word line.
- the transistors and the storage capacitors of the memory cells are arranged in such a way that a transistor and a storage capacitor of different memory cells are alternately arranged along the word lines.
- the bit lines run across the word lines.
- a memory cell comprises a planar transistor and a storage capacitor connected in series with it. Between every two
- Storage capacitors the storage nodes of which are arranged in depressions of a substrate, are arranged two planar transistors which have a common source / drain region. To increase the capacity of the
- Storage capacitor is first created an upper region of the recess, the flanks of which are provided with an oxide.
- the oxide is then removed from the bottom of the depression and the depression is deepened further, so that a lower region of the depression is formed.
- the lower region of the recess is widened by a wet etching process, so that a cross section of the lower region of the recess is larger than a cross section of the upper region.
- the widening of the lower region of the depression increases the surface area of a capacitor dielectric, which covers areas of the depression, and thus increases the capacitance of the storage capacitor.
- EP 0 852 396 describes a DRAM cell arrangement in which a transistor of a memory cell is arranged above a storage capacitor of the memory cell in order to increase the packing density. Active areas of the
- Memory cells are each surrounded by an insulating structure which is arranged in a substrate.
- a depression is produced in the substrate for each memory cell, in the lower region of which a storage node of the storage capacitor and in the upper region of which a gate electrode of the
- Transistors are arranged. An upper source / drain region, a channel region and a lower source / drain region of the transistor are arranged one above the other in the substrate.
- the lower source / drain region is connected to the storage node on a first flank of the depression.
- the insulating structure is adjacent to a second flank of the depression opposite the first flank, so that the storage node does not adjoin the substrate there.
- a capacitor electrode of the storage capacitor is formed by diffusion of dopant into the substrate.
- a bit line is adjacent to the upper source / drain region and runs above the substrate.
- the gate electrode is isolated from the substrate and from the bit lines by a gate dielectric and the insulating structure. The gate electrode is adjacent to a word line that runs above the bit line.
- the invention is based on the problem of specifying a DRAM cell arrangement which has folded bit lines, whose word lines and bit lines can be produced with high electrical conductivity and which can also be produced with a high packing density. Furthermore, a method for their production is to be specified.
- the problem is solved by a DRAM cell arrangement in which memory cells are arranged in columns that run parallel to an y-axis and rows that run parallel to an x-axis in a substrate.
- the memory cells of a column are connected to a bit line that runs above a main surface of the substrate.
- the memory cells of a row are alternately connected to a first word line and a second word line.
- the memory cells each comprise a columnar connection structure.
- First parts of the first word line are each offset in the y direction, ie in the positive direction along the y axis, to one of the connection structures of the memory cells to which the first word line is connected, so that this connection structure overlaps but does not cover from above becomes.
- a second part of the first word line is strip-shaped, runs above the main surface and essentially parallel to the x-axis and adjoins the first parts of the first word line from above.
- Flanks of the first word line are provided with insulating spacers.
- First parts of the second word line are arranged between the spacers of mutually adjacent first word lines of the memory cells.
- the first parts of the second word line are each opposite to the y direction, ie in the negative direction along the y axis, offset to one of the connection structures of the memory cells to which the second word line is connected, so that this connection structure overlaps from above is not covered.
- a second part of the second word line is strip-shaped, runs above the main surface and essentially parallel to the x-axis, adjoins the first parts of the second word line from above and is arranged above the first word line and the bit line. The first word line and the second word line overlap the line.
- the problem is further solved by a method for producing a DRAM cell arrangement in which memory cells are arranged in columns which are parallel to a y-axis and lines that are parallel to an x-axis are generated.
- a columnar connection structure is generated for each of the memory cells.
- Bit lines are generated, each of which is connected to the memory cells of a column.
- a first insulating layer is applied over the connection structures of memory cells.
- First contact holes are produced in the first insulating layer, which expose parts of every second connection structure of the memory cells of a row in such a way that the first contact holes are arranged offset in the y direction to the connection structures.
- Conductive material is deposited so that the first contact holes are filled with first parts of first word lines.
- a second insulating layer is deposited.
- the conductive material and the second insulating layer are structured so that strip-shaped second parts of the first word lines are produced, which run essentially parallel to the x-axis, adjoin the first parts of the first word line from above and are covered by the second insulating layer .
- Flanks of the first word lines are provided with insulating spacers.
- the first insulating layer is selectively etched to the second insulating layer and the spacers, so that parts of the remaining connection structures are exposed in such a way that second contact holes are produced which are opposite to the y-
- connection structures are arranged.
- Conductive material is deposited so that the second contact holes are filled with first parts of second word lines, which are arranged between the spacers of mutually adjacent first word lines.
- the conductive material is structured so that strip-shaped second parts of the second word lines are produced which run essentially parallel to the x-axis, adjoin the first parts of the second word lines from above and are arranged above the first word lines and the bit lines.
- Materials with high electrical conductivities such as WSi, TiSi, MoSi, CoSi, TaSi, are preferably deposited above a semiconductor substrate, since on the one hand they cover edges, which are formed, for example, by depressions in the semiconductor substrate, poorly, ie not uniformly, and on the other should be arranged at a distance from the semiconductor substrate in order to avoid contamination of the semiconductor substrate. Mechanical stresses or damage to a surface of the substrate caused by the deposition are also avoided in this way. Because both the bit lines and the second parts of the first word lines and the second word lines run above the substrate, they can contain materials with high electrical conductivities.
- bit lines and the word lines can be generated simultaneously with gate electrodes of transistors of a periphery of the DRAM cell arrangement by structuring a layer or a layer sequence of conductive materials with the aid of a mask by etching.
- the bit lines and the word lines have a so-called planar structure.
- the DRAM cell arrangement consequently has folded bit lines.
- the DRAM cell arrangement can have a high packing density, since only the spacers, which can be produced with thin horizontal cross sections, ie cross sections parallel to the main surface, laterally separate the first word lines from the second word lines.
- the bit lines and the word lines can be generated after the memory cells have been produced. This is advantageous since the generation of the bit lines and the word lines from metals is made possible, after their application process steps at high temperatures, which can lead to contamination of other parts of the DRAM cell arrangement, for example, are avoided.
- a layer sequence of Ti, TiN and W can be structured to generate the word lines and the bit lines.
- the generation of the word lines are insensitive to adjustment inaccuracies with regard to the connection structures.
- the extensive self-aligned contacting of the connection structures through the word lines enables a high packing density of the DRAM cell arrangement.
- the adjustment of photoresist masks to produce the first word lines and the second word positions only has to guarantee that the connection structures are partially overlapped, since the second word lines are selectively etched to the spacers and the second insulating layer, so that contact holes for the second word lines cannot arise in and adjacent to the first word lines.
- the adjustment inaccuracy is preferably up to a third of the width of the connection structures.
- the DRAM cell arrangement can be generated with a high packing density.
- the first word lines preferably have a width that is equal to the minimum structure size F that can be produced in the technology used to produce the DRAM cell arrangement.
- the bit lines can also have a width and spacing from each other, which are F.
- the first word lines and the second word lines can accordingly be arranged alternately without spacing, directly next to one another or overlapping.
- the memory cell can be produced with an area of F 2 .
- connection structures can protrude beyond the main surface of the substrate.
- flanks of the connection structures are provided with further insulating spacers, between which first parts of the bit lines adjoin.
- Second parts of the bit lines are arranged between the first parts of the bit lines and have a greater width than the first parts of the bit lines.
- the bit lines adjoin the main area and each run between connection structures which are adjacent to one another in the x direction. This has the advantage that the bit lines can be generated largely self-aligned between the connection structures. For this purpose, an insulation is created which surrounds the connection structures provided with the further spacers.
- connection structures With the aid of a strip-shaped mask, the strips of which run parallel to the columns and overlap the respective connection structures of memory cells of a column, trenches are produced in the insulation, etching being carried out selectively to the spacers and the first insulating layer. Subsequently, conductive material is deposited and removed until the insulation is exposed, so that the bit lines are produced in the trench, which do not overlap the connection structures. This is advantageous since otherwise the effective cross section of the connection structures has been reduced, which in turn has resulted in a reduction in the overlap of the connection structures with the word lines.
- a memory cell comprises a transistor and a storage capacitor connected in series with it.
- the transistor is designed as a vertical transistor, so that an upper source / drain device is arranged above a channel area and the channel area is arranged above a lower source / dram device of the transistor.
- the transistor and the storage capacitor are arranged one above the other.
- connection structure is connected to a gate electrode of the transistor.
- a recess can be provided in the substrate for the memory cell, in the lower region of which a storage node of the storage capacitor and in the upper region of the connection structure are arranged. Flats of the lower area of the depression are marked with a
- Capacitor dielectric provided.
- the storage node is electrically isolated from the connection structure.
- at least a first flank of the depression is provided with a gate dielectric.
- a part of the connection structure is arranged at least on the first flank and can act as a gate electrode of the transistor.
- the upper source / dram device is arranged on the main surface of the substrate and adjoins two depressions adjacent to one another in the x direction.
- the wells are filled with conductive material up to a medium height after the application of a capacitor dielectric.
- the conductive material can be deposited, planarized by chemical-mechanical polishing and then etched back to the middle height. Then be exposed parts of the capacitor dielectric are removed, so that surfaces of the depressions are provided with the capacitor dielectric only up to the middle height.
- the depressions are then filled up further by conductive material to an upper height, which is in the lower region, so that the conductive material adjoins the substrate between the middle height and the upper height.
- the conductive material in the recesses forms the storage nodes.
- a gate dielectric is created to cover the storage node.
- insulating material is first applied to the storage node and the gate dielectric is then grown.
- the connection structure is then created in the upper region of the depression. The gate dielectric or the insulating material separate the connection structure from the storage node.
- the depression is produced in a layer sequence, so that the lower source / drain region, the channel region and the upper source / drain region arise from layers of the layer sequence.
- the lower source / drain region is preferably produced by diffusing dopant from the storage node between the upper height and the middle height into the substrate by means of a tempering step.
- the lower source / drain region adjoins only one depression, so that channel regions of different transistors are electrically connected to one another. This is advantageous since floating body effects are avoided in this way.
- the capacitor dielectric Before removing the exposed parts of the capacitor dielectric above the average height, it is advantageous to apply a mask which covers the second flanks of the depressions opposite the first flanks. As a result, the capacitor dielectric is retained on the second flank, so that the storage node only connects to the first flank between the middle height and the top height Adjacent substrate. In this case, the distance between the second flank and the first flank of mutually adjacent depressions can be reduced without leakage currents occurring between the associated storage nodes. The packing density of the DRAM cell arrangement can thus be increased. After the storage nodes have been created, exposed parts of the capacitor dielectric which are arranged on the second flanks above the upper height can be removed.
- the upper source / drain region can be produced by structuring a doped layer of the substrate adjoining the main area.
- the structuring takes place on the one hand through the creation of the depressions.
- separation structures are generated between upper source / drain regions adjacent to one another in the y direction.
- the separating structures can be produced by creating further trenches in the substrate which run parallel to the rows and are arranged between the depressions. The other trenches are then filled with insulating material.
- the upper source / drain region can alternatively be produced by performing an implantation after the creation of the depressions and the separating structures.
- the depressions can be produced in a self-aligned manner between the separating structures in that, after the separating structures have been produced, the substrate is selectively etched with the aid of a strip-like mask, the strips of the mask running transversely to the separating structures.
- the connection structures can first be produced by depositing conductive material after generation of the gate dielectric and structuring with the aid of a mask which covers the second flanks of the depressions. The connection structures are arranged on the first flanks of the depressions and do not completely fill the depressions. The insulating structures are produced by depositing insulating material and etching it back.
- the capacitor dielectric has a first part which covers areas of the lower regions of the depressions up to a lower height which is below the average height, and a second part which is thicker than the first part and areas of the depressions covered between the lower height and the middle height.
- the lower source / dram device, the substrate and the capacitor electrode form a pnp or an npn junction depending on the selected conductivity types, which, triggered by the storage node, can cause leakage currents. If the capacitor dielectric between the capacitor electrode and the second source / dram region is particularly thick, the storage node no longer controls the transition and leakage currents are avoided.
- the first part of the capacitor dielectric is applied over the entire area after the recesses have been produced.
- the wells are filled with conductive material to a lower height, which is below the middle height. Exposed parts of the first part of the
- the capacitor dielectric is then removed.
- the second part of the capacitor dielectric is first applied over the entire surface and is removed from a surface of the conductive material by anisotropic etching. By separating conductive material up to the medium height, the Well further filled. Then proceed as described above.
- a capacitor electrode of the capacitor is arranged in the substrate and adjoins the capacitor dielectric.
- the capacitor electrode can be designed as a doped layer of the substrate common to all capacitors.
- the doped layer can e.g. can be generated by epitaxy or implantation before generation of the memory cells.
- a dopant source is introduced into the depressions, from which dopant diffuses into the substrate in a tempering step and forms the doped layer there.
- the dopant source is e.g. Arsenic glass. After the wells have been created, the arsenic glass is deposited so that surfaces of the wells are covered. The lower areas of the depressions provided with the arsenic glass are e.g. Photoresist filled. Exposed arsenic glass is then removed. It is advantageous to grow a protective oxide after removing the photoresist. The protective oxide prevents arsenic from evaporating in the subsequent annealing step in which arsenic diffuses from the arsenic glass into the substrate.
- the capacitor electrode is produced as a part of the substrate doped with arsenic which surrounds the lower regions of the depressions.
- the first flank is flat in the upper area and the surface of the lower area is curved.
- Gate dielectric depends on the orientation of the first flank relative to the crystal structure of the substrate. If the first flank is flat, a homogeneous growth of the gate dielectric is made possible since, in contrast to a curved surface, a flat surface has a defined orientation relative to the crystal structure. Control characteristics of the transistor, in which the Gate dielectric has a homogeneous thickness, correspond to those of conventional planar transistors and have a particularly high sub-threshold steepness. If part of the capacitor dielectric is grown by thermal oxidation on a surface that has an edge, the oxide on the edge is particularly thin. Leakage currents can therefore occur in the area of the edge. It is therefore advantageous if the capacitor dielectric is produced on a surface which has no edges. Even if the capacitor dielectric is produced by depositing material, edges in the area have a disadvantageous effect, since there are field distortions at the edges, which can lower the breakdown voltage of the capacitor.
- the upper region has an essentially rectangular cross section which is larger than a cross section of the lower region which is essentially circular or elliptical.
- auxiliary spacers are produced on the wells after the upper areas of the well have been produced by separating and anisotropically scratching off material.
- the auxiliary spacers are rounded off by an isotropic etching process, so that exposed parts of the bottom of the depressions have a circumference without corners.
- the lower regions of the depressions are subsequently produced by anisotropic etching selective to the auxiliary spacers.
- the lower region of the depression is subsequently widened by isotropic etching of the substrate, so that its cross section is enlarged. This increases the area of the lower area on which the capacitor dielectric is arranged, so that the capacitance of the storage capacitor is increased.
- an upper surface of the separating structures after the is prevented due to the finite selectivity of etching processes Creation of the wells lies below the main surface.
- a lower layer made of a first material and an upper layer made of a second material are applied to the main surface.
- the separating structures are then produced, the first material being used to fill the further trenches.
- An upper surface of the separating structures lies above the main surface but below an upper surface of the lower layer.
- the depressions are then produced with the aid of the strip-shaped mask by first etching the first material selectively to the second material, so that the upper surface of the separating structures lies unchanged above the main surface, since the auxiliary structures protect the separating structures.
- the depressions can then be produced by etching exposed parts of the substrate, the separating structures and the lower layer serving as a mask. Due to the finite selectivity of the etching process, the separating structures and the lower layer are removed, the upper surfaces of which do not lie below the main surface due to the sufficient thickness of the lower layer after the recesses have been produced.
- the substrate can contain silicon and / or germanium and is preferably monocrystalline so that the gate dielectric can be produced by thermal oxidation.
- bit lines and the word lines can be constructed in multiple layers. For example, can each have a lower layer of doped polysilicon and above that a layer of a material with better electrical conductivity, e.g. Silicide or metal can be provided.
- a material with better electrical conductivity e.g. Silicide or metal
- FIG. 1 a shows a cross section through a substrate after a first layer, a second layer, a third layer, a fourth layer and separating structures have been produced.
- FIG. 1 b shows the cross section from FIG. 1 a after the fourth layer has been removed and auxiliary structures have been produced.
- FIG. 2a shows a top view of the substrate from FIG. 1b after upper regions of depressions and auxiliary spacers have been produced. The position of a second photoresist mask is also shown.
- FIG. 2b shows a cross section perpendicular to the cross section from FIG. 1 a through the substrate after the process steps from FIG. 2a.
- FIG. 3 shows the top view from FIG. 2a after the auxiliary spacers have been rounded off.
- FIG. 4 shows the cross section from FIG. 2b after a lower region of the depression, a capacitor dielectric, a storage node and a third photoresist mask have been produced.
- FIG. 5a shows the cross section of Figure 4 after the
- Transistors a gate dielectric, connection structures, a sixth layer, first spacers and a first insulation were generated.
- FIG. 5b shows the top view from FIG. 2a, in which the
- Connection structures the first spacers, the upper ones Source / dram areas and the separation structures are shown.
- FIG. 6a shows the cross section from FIG. 5a after a seventh layer and an eighth layer
- Figure 6b shows the top view of Figure 2a, in which the
- connection structures the first spacers, parts of the first insulation which are not arranged above the bit lines, parts of the seventh layer which are not arranged below the eighth layer, and the eighth layer are shown.
- FIG. 7a shows the cross section of Figure 1, according to the
- Figure 7b shows the top view of Figure 2a, m the
- Connection structures, the first spacers and areas that are not covered by a sixth photoresist mask are shown.
- Figure 8 shows the top view of Figure 2a, in which the
- Connection structures, the first spacers, the ninth layer, the second spacers and an eighth photoresist mask are shown.
- FIG. 9a shows the cross section from FIG. 7a after a twelfth layer and a thirteenth layer, which form second word lines, a fourteenth layer and third spacers have been produced.
- FIG. 9b shows a cross section through the substrate parallel to FIG. 9a after the process steps from FIG. 9a.
- FIG. 9c shows the top view from FIG. 2a, in which the
- Connection structures, the first spacers, the seventh layer, the ninth layer and the twelfth layer are shown.
- a p-doped substrate S is provided of silicon as a starting material, which is doped p-in a position adjacent to a main surface of the substrate S H layer with a dopant concentration of about lO ⁇ 1 cm -3.
- first layer 1 made of SiO 2
- second layer 2 made of silicon nitride
- third layer 3 made of SiO 2
- fourth layer 4 deposited from silicon nitride
- the fourth layer 4, the third layer 3, the second layer 2, the first layer 1 and the substrate S are anisotropically etched with the aid of a strip-shaped first photoresist mask (not shown), so that first trenches approximately 300 nm deep are produced in the substrate S. be that have a width of about 100 nm and distances of about 100 nm from each other.
- Etchants such as CF4, CHF 3 , C2F5 and HBr are suitable, which are combined according to the material to be etched.
- Separating structures T are produced in the first trenches in that SiO 2 conformally is deposited to a thickness of approximately 200 nm and is planarized by chemical mechanical polishing until an upper surface of the fourth layer 4 is exposed. SiO 2 is then selectively etched back to the silicon nitride, so that an upper surface of the separating structures T lies below an upper surface of the third layer 3 (see FIG. 1 a). Silicon nitride is then deposited and planarized by chemical mechanical polishing until the upper surface of the third layer 3 is exposed. In this way, auxiliary structures Q made of silicon nitride are arranged above the separating structures T (see FIG. 1b).
- SiO 2 is selectively etched to silicon nitride with, for example, C4F6, CO until the second layer 2 is partially exposed. Silicon nitride is then etched, so that the auxiliary structures Q and exposed parts of the second layer 2 are removed.
- the finite selectivity of the etching process first partially cuts through the first layer 1 and then produces upper regions of depressions V.
- the separating structures T and the third layer 3 act as a thick mask.
- the upper regions of the depressions V are approximately 300 nm deep in the substrate S and have parallels to the main surface H.
- Cross sections that are square and whose dimensions are approximately 100 nm. Distances between mutually adjacent depressions V are approximately 100 nm from one another (see FIGS. 2a and 2b).
- Auxiliary spacers f are produced in the depressions V by depositing SiO 2 in a thickness of approximately 30 nm and etching back anisotropically (see FIGS. 2a and 2b). Exposed parts of the bottoms of the depressions are essentially square and have a side length of approximately 40 nm.
- an isotropic etch-back is then carried out using, for example, CF4 as the etchant (see FIG. 3).
- Exposed parts of the bottoms of the depressions V are essentially circular and have a diameter of approximately 100 nm.
- Silicon is then anisotropically etched to S1O2 using, for example, HBr, so that lower regions of the depressions V are formed which, because of the auxiliary spacer f acting as a mask, have circular horizontal cross sections.
- the depressions V are now approximately 7 ⁇ m deep (see FIG. 4).
- the separating structures T and the third layer 3 act as a thick mask.
- the upper regions of the depressions V each have four lateral flat first surfaces F1.
- the lower regions of the depressions V have a curved second surface F2.
- a horizontal, i.e. Cross section of the lower region of one of the depressions V lying parallel to the main surface H has a curved circumference.
- Part of the substrate S is in particular under corners of the upper regions of the
- Wells V are arranged because the auxiliary spacers f cover at least the corners and are consequently not etched deeper there.
- arsenic glass is deposited in a thickness of approximately 10 nm.
- the depressions V provided with the arsenic glass are filled with photoresist up to a height h of approximately 1 ⁇ m below the main surface H (cf. FIG. 4).
- Exposed arsenic glass is then removed.
- a protective oxide (not shown) is grown. The protective oxide prevents arsenic from evaporating in a subsequent tempering step at approximately 1000 ° C., in which arsenic diffuses from the arsenic glass m the substrate S.
- the capacitor electrode E is produced as a part of the substrate S doped with arsenic, which surrounds parts of the lower regions of the depressions V (see FIG. 4).
- the protective oxide and the auxiliary spacer f are then removed with dilute hydrofluoric acid.
- first part d1 of a capacitor dielectric areas of the depressions V provided with silicon nitride, which is then partially oxidized, so that the first part dl of the capacitor dielectric is produced as a so-called NO layer with an approximately 3 nm oxide-equivalent thickness (see FIG. 4).
- in situ doped polysilicon is deposited to a thickness of approximately 100 nm and planarized by chemical mechanical polishing until the second layer 2 is exposed.
- the third layer 3 is removed and the separating structures T are removed somewhat.
- the polysilicon is then etched back to a depth of 1.1 ⁇ m below the main surface H by anisotropic etching, so that the depressions V are filled with polysilicon to a lower height u (see FIG. 4).
- Exposed parts of the first part dl of the capacitor dielectric are removed with, for example, hydrofluoric acid.
- SiO 2 is deposited in a thickness of approximately 15 nm and etched back anisotropically (see FIG. 4).
- the second part d2 of the capacitor dielectric is thicker than the first part dl.
- the storage nodes K are enlarged by depositing polysilicon doped in situ to a thickness of approximately 100 nm and then etching back to a depth of approximately 250 nm below the main surface H.
- the depressions V are filled with polysilicon up to an average height m (see FIG. 4).
- Capacitor dielectric only from the lower height u to the middle height m. Subsequently, m situ doped polysilicon with a thickness of approximately 100 nm is deposited and planarized by chemical mechanical polishing until the second layer 2 is exposed.
- upper source / drain regions S / DI of vertical transistors are produced in the substrate S by implantation with n-doping ions. Because of the separating structures T and the depressions V, the upper source / drain regions S / DL have square horizontal cross sections with a side length of approximately 100 nm. Upper source / drain regions S / D1 which are adjacent to one another are separated from one another by the separating structures T or by the depressions V.
- the polysilicon is then etched back to a depth of approximately 200 nm below the main surface H, so that the storage nodes K are further thickened.
- the depressions V are filled with polysilicon up to an upper height h
- the storage nodes K adjoin the substrate S at the first flanks of the depressions V between the middle height and the upper height o. Upper parts of the storage nodes K are arranged in the upper regions of the depressions V.
- dopant diffuses from the storage node K m to the substrate S, so that lower source / dram areas S / D2 of the transistors are produced, which in the range between the average height m and the upper height o to the first flanks of the depressions V adjoin.
- the second layer 2 is then removed using, for example, hot phosphoric acid as an etchant.
- a gate dielectric Gd is formed on the flanks of the upper regions of the depressions V by thermal oxidation Main area H and generated on the storage node K (see Figure 5a).
- a fifth layer 5 of in-situ doped polysilicon is then deposited to a thickness of approximately 60 nm, so that the upper regions of the depressions V are filled.
- An approximately 100 nm thick sixth layer 6 made of silicon nitride is deposited over this.
- connection structures A have square horizontal cross sections with a side length of approximately 100 nm.
- Terminal structures A are deposited in silicon nitride in a thickness of approximately 20 nm and are etched back until the gate dielectric Gd is exposed on the main area H.
- S1O2 conformal deposition of S1O2 in a thickness of approx. 200 nm and chemical-mechanical polishing until the sixth layer 6 is exposed, a first insulation II is produced, which surrounds the connection structures A provided with the first spacers Spl (see FIG. 5a).
- the strips of which run transversely to the separating structures T have a width of approximately 100 nm and a distance of approximately 100 nm from one another and at least partially overlap the connecting structures, S1O2 is selectively etched to silicon nitride, so that m the first
- Isolation II strip-shaped second trench are generated until parts of the main area H are exposed.
- the bit lines are produced in the form of a strip-like second trench by depositing an approximately 15 nm-thick n-doped seventh layer 7 made of doped polysilicon. / Then an eighth layer 8 of tungsten silicide is deposited to a thickness of about 60 nm, so that the strip-like second trenches are filled, and planarized by chemical mechanical polishing until the sixth layer 6 is exposed.
- the bit lines are formed by the seventh layer 7 and the eighth layer 8 (see FIG. 6a). By scratching, an upper surface of the bit lines lies below an upper surface of the first insulation II.
- a subsequent tempering step at approximately 800 ° C.
- the bit lines have first parts that adjoin the first spacers Spl of adjacent connection structures A and have a width of approximately 60 nm. Second parts of the bit lines are arranged between the first parts of the bit lines and have a width of approximately 100 nm (see FIG. 6b). The sensitivity to adjustment inaccuracies for generating the bit lines between the connection structures A is low, since the first spacers Spl and the sixth layer 6 are etched selectively.
- S1O2 is then deposited and planarized by chemical mechanical polishing until the sixth layer 6 is exposed.
- the first insulation II is expanded so that it covers the bit lines (see FIG. 6a).
- first contact holes are produced in the sixth layer 6, which expose parts of every second connection structure A of the memory cells of a row in such a way that the first contact holes in y- Direction offset to the connection structures A are arranged.
- CHF3 is etched selectively for the first insulation II and silicon, as an etchant.
- a ninth layer 9 made of polysilicon, doped in situ and about 60 nm thick, and a tenth layer 10 made of tungsten silicide about 50 nm thick are deposited.
- the first contact holes are filled with conductive material.
- a strip-like seventh photoresist mask the strips of which run parallel to the separating structures T, have a width of approximately 100 nm and distances of approximately 100 nm from one another and at least partially overlap the first contact holes, the eleventh layer 11, the tenth layer 10 and the ninth layer 9 structured until the first insulation II is exposed.
- the first word lines are through the ninth
- the first word lines have first parts which are arranged in the first contact holes and adjoin second parts of the first word lines which have strip-shaped cross sections.
- second spacers Sp2 are produced on the flanks of the second parts of the first word lines.
- silicon nitride is deposited in a thickness of approximately 100 nm and planarized by chemical mechanical polishing until a flat surface is produced (see FIG. 7a).
- a stripe-shaped eighth photoresist mask P ' With the help of a stripe-shaped eighth photoresist mask P ', the stripes of which are approximately 300 nm wide, are spaced approximately 100 nm apart, run transversely to the separating structures T and are arranged over connection structures A which are contacted by the first word lines Silicon nitride selectively etched to SiO 2 and silicon with, for example, CHF 3 until the connection structures A, which are not contacted by the first word lines, are partially exposed (see FIG. 8).
- second contact holes 12 in the second insulation which are arranged opposite to the y-direction offset to the connection structures A.
- the second contact holes are produced in a self-aligned manner between the second parts of the first word lines, since etching is selective to the second spacers Sp2 and to the eleventh layer 11.
- an approximately 60 nm thick in-situ doped twelfth layer 12 made of polysilicon and an approximately 50 nm thick thirteenth layer 13 made of tungsten silicide are deposited (see FIG. 9a).
- the second contact holes are thereby filled with conductive material, so that first parts of the second word lines are formed (see FIG. 9b).
- the twelfth layer 12 and the thirteenth layer 13 above the first word lines form second parts of the second word lines which have a strip-shaped cross section (see FIGS. 9a, 9b, 9c).
- a DRAM cell arrangement with folded bit lines is generated.
- a memory cell comprises one of the vertical transistors and one of the capacitors, which is connected in series with the transistor, and has an area of 4F 2 , where F is 100 nm.
- Each memory cell is connected to one of the bit lines and to one of the first or one of the second word lines.
- the memory cells are arranged in columns that run parallel to the y-axis y and in rows that run parallel to the x-axis x, with the columns running parallel to the bit lines and the lines running parallel to the word lines.
- the first parts of the first word lines overlap each second of the connection structures A along the lines, in each case offset in the y direction to the associated one
- Connection structure A are arranged.
- the first parts of the second word lines overlap the other connection structures A, wherein they are each offset from the associated connection structure A opposite to the y direction.
- connection structures A which are arranged on the first flanks of the upper regions of the depressions V, act as gate electrodes of the transistors.
- Channel regions of the transistors are parts of the substrate S which are arranged between the upper source / drain regions S / D1 and the lower source / drain regions S / D2.
- the channel regions of the transistors are connected to one another so that floating body effects are avoided.
- the word lines and Bit lines also contain other conductive materials than those mentioned in the exemplary embodiment.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99955719A EP1129483A1 (de) | 1998-09-30 | 1999-09-15 | Dram-zellenanordnung und verfahren zu deren herstellung |
JP2000572936A JP3805624B2 (ja) | 1998-09-30 | 1999-09-15 | Dramセル装置およびその製造方法 |
US09/806,427 US6492221B1 (en) | 1998-09-30 | 1999-09-15 | DRAM cell arrangement |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19845004A DE19845004C2 (de) | 1998-09-30 | 1998-09-30 | DRAM-Zellenanordnung und Verfahren zu deren Herstellung |
DE19845004.4 | 1998-09-30 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2000019528A1 WO2000019528A1 (de) | 2000-04-06 |
WO2000019528A9 true WO2000019528A9 (de) | 2000-11-09 |
Family
ID=7882901
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DE1999/002939 WO2000019528A1 (de) | 1998-09-30 | 1999-09-15 | Dram-zellenanordnung und verfahren zu deren herstellung |
Country Status (7)
Country | Link |
---|---|
US (1) | US6492221B1 (de) |
EP (1) | EP1129483A1 (de) |
JP (1) | JP3805624B2 (de) |
KR (1) | KR100436413B1 (de) |
DE (1) | DE19845004C2 (de) |
TW (1) | TW452831B (de) |
WO (1) | WO2000019528A1 (de) |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10024876A1 (de) | 2000-05-16 | 2001-11-29 | Infineon Technologies Ag | Vertikaler Transistor |
US6339241B1 (en) * | 2000-06-23 | 2002-01-15 | International Business Machines Corporation | Structure and process for 6F2 trench capacitor DRAM cell with vertical MOSFET and 3F bitline pitch |
DE10038728A1 (de) * | 2000-07-31 | 2002-02-21 | Infineon Technologies Ag | Halbleiterspeicher-Zellenanordnung und Verfahren zu deren Herstellung |
US6509624B1 (en) * | 2000-09-29 | 2003-01-21 | International Business Machines Corporation | Semiconductor fuses and antifuses in vertical DRAMS |
JP3549499B2 (ja) * | 2001-07-04 | 2004-08-04 | 松下電器産業株式会社 | 半導体集積回路装置ならびにd/a変換装置およびa/d変換装置 |
DE10306281B4 (de) * | 2003-02-14 | 2007-02-15 | Infineon Technologies Ag | Anordnung und Verfahren zur Herstellung von vertikalen Transistorzellen und transistorgesteuerten Speicherzellen |
WO2007027169A2 (en) * | 2005-08-30 | 2007-03-08 | University Of South Florida | Method of manufacturing silicon topological capacitors |
CA2579199C (en) * | 2004-09-10 | 2013-04-30 | Syngenta Limited | Substituted isoxazoles as fungicides |
US7326611B2 (en) * | 2005-02-03 | 2008-02-05 | Micron Technology, Inc. | DRAM arrays, vertical transistor structures and methods of forming transistor structures and DRAM arrays |
JP5060413B2 (ja) * | 2008-07-15 | 2012-10-31 | 株式会社東芝 | 半導体記憶装置 |
US9171847B1 (en) * | 2014-10-02 | 2015-10-27 | Inotera Memories, Inc. | Semiconductor structure |
CN111386229B (zh) | 2017-12-15 | 2021-12-24 | 赫斯基注塑系统有限公司 | 用于容器的封闭盖 |
CN111834364B (zh) * | 2019-04-19 | 2023-08-29 | 华邦电子股份有限公司 | 动态随机存取存储器 |
CN116648062A (zh) * | 2021-07-08 | 2023-08-25 | 长鑫存储技术有限公司 | 半导体器件结构及制备方法 |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62274771A (ja) * | 1986-05-23 | 1987-11-28 | Hitachi Ltd | 半導体メモリ |
US5008214A (en) | 1988-06-03 | 1991-04-16 | Texas Instruments Incorporated | Method of making crosspoint dynamic RAM cell array with overlapping wordlines and folded bitlines |
JPH0319363A (ja) * | 1989-06-16 | 1991-01-28 | Toshiba Corp | 半導体記憶装置 |
US5214603A (en) * | 1991-08-05 | 1993-05-25 | International Business Machines Corporation | Folded bitline, ultra-high density dynamic random access memory having access transistors stacked above trench storage capacitors |
KR0141218B1 (ko) * | 1993-11-24 | 1998-07-15 | 윤종용 | 고집적 반도체장치의 제조방법 |
US5937296A (en) * | 1996-12-20 | 1999-08-10 | Siemens Aktiengesellschaft | Memory cell that includes a vertical transistor and a trench capacitor |
DE19718721C2 (de) * | 1997-05-02 | 1999-10-07 | Siemens Ag | DRAM-Zellenanordnung und Verfahren zu deren Herstellung |
TW429620B (en) * | 1997-06-27 | 2001-04-11 | Siemens Ag | SRAM cell arrangement and method for its fabrication |
EP0899790A3 (de) * | 1997-08-27 | 2006-02-08 | Infineon Technologies AG | DRAM-Zellanordnung und Verfahren zu deren Herstellung |
EP0924766B1 (de) * | 1997-12-17 | 2008-02-20 | Qimonda AG | Speicherzellenanordnung und Verfahren zu deren Herstellung |
-
1998
- 1998-09-30 DE DE19845004A patent/DE19845004C2/de not_active Expired - Fee Related
-
1999
- 1999-09-15 WO PCT/DE1999/002939 patent/WO2000019528A1/de not_active Application Discontinuation
- 1999-09-15 US US09/806,427 patent/US6492221B1/en not_active Expired - Lifetime
- 1999-09-15 EP EP99955719A patent/EP1129483A1/de not_active Withdrawn
- 1999-09-15 KR KR10-2001-7003837A patent/KR100436413B1/ko not_active IP Right Cessation
- 1999-09-15 JP JP2000572936A patent/JP3805624B2/ja not_active Expired - Fee Related
- 1999-09-27 TW TW088116496A patent/TW452831B/zh not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
KR100436413B1 (ko) | 2004-06-16 |
DE19845004A1 (de) | 2000-04-13 |
US6492221B1 (en) | 2002-12-10 |
DE19845004C2 (de) | 2002-06-13 |
JP3805624B2 (ja) | 2006-08-02 |
EP1129483A1 (de) | 2001-09-05 |
WO2000019528A1 (de) | 2000-04-06 |
JP2003521103A (ja) | 2003-07-08 |
TW452831B (en) | 2001-09-01 |
KR20010079925A (ko) | 2001-08-22 |
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