CN110391242B - L-shaped step-shaped word line structure, manufacturing method thereof and three-dimensional memory - Google Patents
L-shaped step-shaped word line structure, manufacturing method thereof and three-dimensional memory Download PDFInfo
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- CN110391242B CN110391242B CN201910705463.0A CN201910705463A CN110391242B CN 110391242 B CN110391242 B CN 110391242B CN 201910705463 A CN201910705463 A CN 201910705463A CN 110391242 B CN110391242 B CN 110391242B
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/20—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by three-dimensional arrangements, e.g. with cells on different height levels
- H10B41/23—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels
- H10B41/27—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels the channels comprising vertical portions, e.g. U-shaped channels
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/40—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the peripheral circuit region
- H10B41/41—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the peripheral circuit region of a memory region comprising a cell select transistor, e.g. NAND
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- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B43/00—EEPROM devices comprising charge-trapping gate insulators
- H10B43/20—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels
- H10B43/23—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels
- H10B43/27—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels the channels comprising vertical portions, e.g. U-shaped channels
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B43/00—EEPROM devices comprising charge-trapping gate insulators
- H10B43/40—EEPROM devices comprising charge-trapping gate insulators characterised by the peripheral circuit region
Abstract
An L-shaped step-shaped word line structure, a manufacturing method thereof and a three-dimensional memory are provided, wherein the word line structure comprises: the long side of each L-shaped word line unit extends along the second direction and is adjacent to a grid line gap, the short side of each L-shaped word line unit extends along the first direction, and the short side of each L-shaped word line unit comprises a word line leading-out terminal; the word line leading-out end is formed in a step-shaped laminated structure, the laminated structure comprises a plurality of laminated pairs formed by insulating materials, a region, close to a grid line gap, of one laminated layer in each laminated pair serves as a replacement metal region, the replacement metal region comprises a short-edge region surface metal layer located on the surface and a short-edge region internal metal layer located inside, in the first direction, the length of the short-edge region surface metal layer is larger than that of the short-edge region internal metal layer, and the word line leading-out end corresponds to the short-edge region surface metal layer. When the etching selection ratio is not high enough, even if the etching is excessive, the phenomenon of word line short circuit is not generated.
Description
Technical Field
The disclosure belongs to the technical field of semiconductor memories and integration, and relates to an L-shaped step-shaped word line structure, a manufacturing method thereof and a three-dimensional memory.
Background
Three-dimensional NAND memory technology is currently the technology that is being developed with emphasis in the country.
Three-dimensional NAND memories face the increasing difficulty of integration in the future. The three-dimensional NAND memories with 128 layers or more face the difficulty of word line connection process, as the number of layers of the three-dimensional NAND memories increases, the etching requirement of word line connection holes is higher and higher in selection ratio, otherwise, the probability that the word line leading-out ends/welding points (pads) are broken down by etching of the connection holes is greatly increased, and therefore short circuit among word lines is caused. Meanwhile, the difficulty of designing a word line terminal (SS) of the three-dimensional memory is gradually increased.
Disclosure of Invention
Technical problem to be solved
The present disclosure provides an L-shaped step-like word line structure, a method for fabricating the same, and a three-dimensional memory, so as to at least partially solve the above-mentioned technical problems.
(II) technical scheme
According to an aspect of the present disclosure, there is provided an L-shaped step-like word line structure including: a plurality of L-shaped word line units, wherein one side of the long side of each L-shaped word line unit extends along the second direction (y direction) and is adjacent to a gate line gap, one side of the short side extends along the first direction (x direction) and the short side comprises a word line leading-out terminal; the word line leading-out end is formed in a step-shaped laminated structure, the laminated structure comprises a plurality of laminated pairs formed by insulating materials, a region, close to a grid line gap, of one laminated layer in each laminated pair serves as a replacement metal region, the replacement metal region comprises a short-edge region surface metal layer located on the surface and a short-edge region internal metal layer located inside, in the first direction, the length of the short-edge region surface metal layer is larger than that of the short-edge region internal metal layer, and the word line leading-out end corresponds to the short-edge region surface metal layer.
In some embodiments of the present disclosure, the word line leading-out terminal is used for connecting a connection hole welding point of the logic control circuit, and is located at a position, in the short-side area surface metal layer, where a distance from the gate line gap is greater than a length of the short-side area internal metal layer.
In some embodiments of the present disclosure, the replacement metal region further includes a long-side-region surface metal layer located on the surface and a long-side-region internal metal layer located inside, and the length of the long-side-region surface metal layer is equal to the length of the long-side-region internal metal layer in the second direction.
In some embodiments of the present disclosure, the plurality of L-shaped word line units are sequentially connected along the first direction and are distributed in a step shape.
In some embodiments of the present disclosure, the plurality of L-shaped word line units are stacked along the third direction and are distributed stepwise along the second direction.
In some embodiments of the present disclosure, the plurality of L-shaped word line units is at least one pair of L-shaped word line units, two paired L-shaped word line units are separated by a gate line gap and distributed in a staggered mirror image, the offsets differ by a height of one step, the height of one step is equal to the height of one stacked pair, the direction of the offset is along a third direction (z direction), and the third direction is perpendicular to both the first direction and the second direction.
In some embodiments of the present disclosure, the L-shaped step-like word line structure further includes: and the protective layer covers among the plurality of L-shaped word line units and above each word line unit, and the gate line gap penetrates through the upper surface of the protective layer.
In some embodiments of the present disclosure, the L-shaped word line cell long side is used to connect to a core (core) region.
According to another aspect of the present disclosure, a method for fabricating an L-shaped step-like word line structure is provided, which includes: making a stepped laminated structure including a plurality of laminated pairs formed of an insulating material, each of the laminated pairs serving as a step; dividing the laminated structure into a plurality of areas, wherein the laminated structure of each area is used for forming an L-shaped word line unit; processing the tail end of the surface step of the laminated structure of each area, so that the etching rate of the tail end of the surface step is higher than that of the structure below the tail end of the surface step along the first direction; etching the processed laminated structure to form a gate line gap, wherein the gate line gap extends along the second direction and the depth direction of the etching is vertical to the surface of the laminated structure; etching and hollowing a region, close to the gate line gap, of one lamination in each lamination pair based on the gate line gap, wherein the corresponding size of the etched region of one lamination in the surface step is larger than that of the etched region of the structure under the surface step along the first direction; depositing a metal material in the hollowed area to obtain a replacement metal area, wherein the replacement metal area comprises a short-edge area surface metal layer positioned on the surface and a short-edge area internal metal layer positioned inside, the length of the short-edge area surface metal layer is greater than that of the short-edge area internal metal layer in the first direction, and the word line leading-out end corresponds to the short-edge area surface metal layer; and forming a plurality of L-shaped word line units, wherein one long side of each L-shaped word line unit extends along the second direction and is adjacent to one gate line gap, one short side of each L-shaped word line unit extends along the first direction, and the short side of each L-shaped word line unit comprises the word line leading-out terminal.
In some embodiments of the present disclosure, when the stacked structure comprises a stacked pair of silicon oxide and silicon nitride, the surface step end of the stacked structure of each region is processed in a manner that: and increasing the nitrogen concentration in the silicon nitride at the tail end of the surface step by means of ion implantation or selective deposition.
In some embodiments of the present disclosure, before the step of etching the processed stacked structure to form a gate line gap, the method further includes: and forming a protective layer.
In some embodiments of the present disclosure, the step of obtaining the replacement metal region further comprises: and forming a connecting hole for connecting the logic control circuit, wherein the connecting hole penetrates through the protective layer and is connected with a connecting hole welding point of the word line leading-out end in a position corresponding to the position of the connecting hole welding point, and the distance from the connecting hole welding point to the grid line gap in the metal layer on the surface of the short edge area is larger than the length of the metal layer in the short edge area.
In some embodiments of the present disclosure, the stepped lamination structure protrudes outward along the first direction and/or the second direction.
In some embodiments of the present disclosure, the replacement metal region further includes a long-side-region surface metal layer located on the surface and a long-side-region internal metal layer located inside, and the length of the long-side-region surface metal layer is equal to the length of the long-side-region internal metal layer in the second direction.
According to yet another aspect of the present disclosure, there is provided a three-dimensional memory including any one of the L-shaped stepped word line structures mentioned in the present disclosure.
(III) advantageous effects
According to the technical scheme, the L-shaped step-shaped word line structure, the manufacturing method thereof and the three-dimensional memory provided by the disclosure have the following beneficial effects:
the size of a replacement metal area on the tail end surface layer of the L-shaped short-side step is larger than that of an inner replacement metal area in the first direction (x direction) based on the grid line gap, so that the position of a connecting hole (SSCT) perpendicular to the plane can be positioned based on the grid line gap, the SSCT is set to be larger than the size of the replacement metal area inside the tail end of the L-shaped short-side step in the first direction, when the SSCT is connected with the replacement metal area on the tail end surface layer of the L-shaped short-side step, a plurality of lamination pairs in a lamination structure are arranged below the SSCT, for example, a plurality of silicon oxide/silicon nitride lamination pairs are arranged below the SSCT, and therefore the insulating layer is arranged below the metal layer of each connection (contact) drop point, and therefore the phenomenon that word lines are short-circuited is avoided even if etching is excessive under the condition that the etching selection ratio is not high enough is ensured.
Drawings
Fig. 1 is a top view of an L-shaped step word line structure according to an embodiment of the present disclosure.
Fig. 2 is a schematic structural diagram of a circled portion a of the L-shaped step-like word line structure shown in fig. 1, taken along line a1-a1, and corresponding to a cross-sectional view in the x direction of the L-shaped short side.
Fig. 3 is a schematic structural diagram of a circled portion B of the L-shaped step-like word line structure shown in fig. 1, taken along line B1-B1, and corresponding to a y-direction cross-sectional view of the L-shaped short side.
Fig. 4 is a schematic structural diagram of a circled portion a of the L-shaped step-like word line structure shown in fig. 1, taken along line a2-a2, corresponding to a cross-sectional view in the x-direction of the long side of the L-shape.
Fig. 5 is a schematic structural diagram of a circled portion B of the L-shaped step-like word line structure shown in fig. 1, taken along line B2-B2, corresponding to a y-direction cross-sectional view of the long side of the L-shape.
Fig. 6 is a top view (a) and a perspective view (b) of an L-shaped stepped word line structure including a plurality of word line units stacked along a first direction (z direction) and a perspective view of the L-shaped stepped word line structure with an enlarged detail.
Fig. 7 is a schematic structural diagram of a three-dimensional memory including an L-shaped step-like word line structure shown in fig. 1, in which a connection between a logic control circuit and a word line is realized by contacting a connection hole to a short-side-area surface metal layer.
Fig. 8 is a schematic view of the structure shown in fig. 7, taken along line A3-A3, with the circled portion a being a cross-sectional view in the x-direction corresponding to the short side of the L-shape.
Fig. 9 is a flowchart illustrating a method for fabricating an L-shaped step-like word line structure according to an embodiment of the present disclosure.
[ notation ] to show
1-word line cell;
11 a protective layer; 12-a laminated structure;
121-a first laminate material; 122-a second laminate material;
22-replacement metal regions;
221-short edge area surface metal layer; 222-short side area inner metal layer;
223-long side area surface metal layer; 224-metal layer inside the long side region;
3-grid Line slits (GSL, Gate Line Slit); 4-connecting hole.
Detailed Description
In the prior art, a control circuit of a three-dimensional memory and a word line (wordline) are connected with a Step-shaped wordline terminal (SS, sight Step) through a connection hole (SSCT) perpendicular to a plane. With the ever increasing height of three-dimensional memories, the probability of SSCT breaking down SS, thereby causing two or more word lines to short, is increasing. Three-dimensional memories of 128 and 192 layers require SSCT etch selectivity higher than 400 and 600, while three-dimensional memories above 192 layers require higher SSCT etch selectivity. However, current etching techniques do not meet this selectivity requirement.
The utility model provides a L shape step form word line structure and manufacturing method and three-dimensional memory thereof, through set up the replacement metal area of L shape minor face step terminal surface layer bigger than the size of inside replacement metal area in first direction (x direction) based on the grid line gap, thus can position the position of the perpendicular to plane's connecting hole (SSCT) based on the grid line gap, set up SSCT to be greater than the position of the replacement metal area size of L shape minor face step terminal inside in first direction, thus when SSCT and the replacement metal area of L shape minor face step terminal surface layer are connected, correspond to its below be a plurality of lamination pairs in the lamination structure, for example for a plurality of silicon oxide/silicon nitride lamination pairs, then realized that the metal layer below each connection (contact) drop is the insulating layer, so as to ensure under the condition that the etching selection ratio is not enough, even etch excessively, the phenomenon of word line short circuit does not occur.
In the L-shaped step-like word line structure of the present disclosure, the L-shape is a shape appearing in a top view, and the L-shaped step-like word line structure includes at least two word line units. In an embodiment, a plurality (two or more) of word line units may be sequentially connected along the first direction (x direction) and distributed in a step-like manner, that is, a plurality of word line units are included along the first direction (x direction), a word line terminal end of a previous word line unit in the plurality of word line units and a word line terminal end of a next word line unit in the plurality of word line units are distributed in a step-like manner, for example, four word line units distributed along the x direction are illustrated in fig. 1, wherein a connection relationship between two adjacent word line units is illustrated in fig. 2. In another embodiment, the plurality of word line units may also be stacked along the third direction (z direction) and distributed in a step-like manner, that is, the stacked plurality of word line units sequentially protrude outward along the second direction (y direction, which is a negative y-axis direction illustrated in fig. 6 (b)), so as to form a stack of the plurality of word line units distributed in a step-like manner, where a height difference h of the step is a height of one stack pair, two stacked word line units along the z direction illustrated in fig. 6 (a) and a form of the step-like distribution illustrated in fig. 6 (b).
In the embodiment of the present disclosure, in the L-shaped step-like word line structure, the manufacturing method of the replacement metal region is obtained by etching the second lamination material located in the partial regions at the two end portions of the gate line gap by using the gate line gap and then filling the second lamination material with metal, so in an embodiment, the word line units are paired, and the entire word line units are described as paired L-shaped word line units (two word line units in a "convex" shape are illustrated in fig. 1), and the paired two word line units are separated by the gate line gap and distributed in a staggered mirror image (with a difference of height of one step), as shown in fig. 1 and fig. 2. Other preparation methods can form the L-shaped word line units on one side of the gate line gap independently, so that the number of the word line units can be multiple (more than 1), including odd numbers and even numbers, and is not limited to the paired even number form.
In the disclosed L-shaped step-like word line structure, the long side of the L-shape is used for connecting a core (core) area, and the short side of the L-shape is used as a contact terminal/welding point (pad) connected with a control circuit. Through adjusting ion concentration to L shape minor face step terminal surface layer region (or adopt other regulation and control modes, any mode that can realize the etching rate differentiation is all can), make the surface layer region faster than the etching rate of inner zone (wet process corrosion, or other etching means), thereby based on the etching rate difference of top layer and interior material, obtain the structure that the size of minor face regional surface metal layer is bigger than the regional interior metal layer of minor face of its below in first direction (x direction), namely in first direction, the length of regional surface metal layer of minor face is greater than the length of regional interior metal layer of minor face, in regional surface metal layer below of minor face, the part that leans in is regional inner metal layer of minor face, the part that leans out is in the laminated structure (not etched a plurality of stromatolites of reservation). Thus, the structure that the bottom corresponding to the edge position of the L-shaped surface metal is the insulating layer is formed, and when the etching selection ratio is not high enough, the phenomenon that the word line is short-circuited can be ensured even if the etching is excessive when the etching selection ratio is carried out during the etching contact of the connecting hole.
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
First embodiment
In a first exemplary embodiment of the present disclosure, an L-shaped step-like word line structure is provided.
Fig. 1 is a top view of an L-shaped step word line structure according to an embodiment of the present disclosure. Fig. 2 is a schematic structural diagram of a circled portion a of the L-shaped step-like word line structure shown in fig. 1, taken along line a1-a1, and corresponding to a cross-sectional view in the x direction of the L-shaped short side. Fig. 3 is a schematic structural diagram of a circled portion B of the L-shaped step-like word line structure shown in fig. 1, taken along line B1-B1, and corresponding to a y-direction cross-sectional view of the L-shaped short side. Fig. 4 is a schematic structural diagram of a circled portion a of the L-shaped step-like word line structure shown in fig. 1, taken along line a2-a2, corresponding to a cross-sectional view in the x-direction of the long side of the L-shape.
Fig. 5 is a schematic structural diagram of a circled portion B of the L-shaped step-like word line structure shown in fig. 1, taken along line B2-B2, corresponding to a y-direction cross-sectional view of the long side of the L-shape.
It should be noted that, in the present embodiment, one word line unit is illustrated as a stacked structure formed by four stacked pairs, and therefore, corresponding to the long-side cross-sectional views in fig. 3 and 5, it is apparent that the surface metal layer 221 of the short-side region of the corresponding word line terminal is located at the top layer of the four stacked pairs, and in order to illustrate that the stacked pairs of the insulating layers are located below the word line terminals of two word line units, 6 stacked pairs are illustrated in fig. 3 and 5; in fig. 2 and 4, two L-shaped word line unit pairs along the first direction (x direction) are illustrated, and the tail end of the word line leading-out end of the former word line unit pair and the head end of the word line leading-out end of the latter word line unit pair of two adjacent L-shaped word line unit pairs are distributed in a step shape. Inside each L-shaped pair of word line cells, the two word line cells in the pair are separated by the gate line gap and distributed in a staggered mirror image, the offsets differ by one step height, and for clarity, the length of the short-side surface metal layer 221 on the surface layer (top layer) is greater than the length of the short-side internal metal layer 222 below (inside) the short-side surface metal layer along the first direction, which shows 5 stacked pairs. The cross-sectional structure of the short side and the long side of the plurality (two or more) of L-shaped word line cell pairs can be schematically shown by those skilled in the art.
As shown in fig. 1 to 5, the L-shaped step-like word line structure of the present disclosure includes: at least one pair of L-shaped word line units, in each pair of L-shaped word line units, one long side of each L-shaped word line unit 1 extends along the second direction (y direction) and is adjacent to a gate line gap 3, one short side of each L-shaped word line unit 1 extends along the first direction (x direction) and the short side of each L-shaped word line unit comprises a word line leading-out terminal; the word line leading-out end is formed on a laminated structure 12, the laminated structure 12 includes a plurality of laminated pairs formed by insulating materials, a region close to the gate line slit 3 by one laminated layer (for example, the laminated layer formed by the second laminated material 122) in each laminated pair is used as a replacement metal region 22, the replacement metal region 22 includes a short-side-region surface metal layer 221 located on the surface and a short-side-region internal metal layer 222 located inside, in the first direction, the length of the short-side-region surface metal layer 221 is greater than that of the short-side-region internal metal layer 222, and the word line leading-out end corresponds to the short-side-region surface metal layer 221.
In this embodiment, the long side of the L-shape is used to connect to the core (core) area, and the short side of the L-shape is used as the contact/pad (pad) for connection to the control circuitry.
In the L-shaped short side, as shown in fig. 1-3, the replacement metal region 22 includes a short side region surface metal layer 221 located on the surface and a short side region internal metal layer 222 located inside, and in the first direction, the length of the short side region surface metal layer 221 is greater than that of the short side region internal metal layer 222. As shown in fig. 1, 4, and 5, the replacement metal region 22 includes a long-side-region surface metal layer 223 located on the surface and a long-side-region inner metal layer 224 located inside in the L-shaped long side, and the length of the long-side-region surface metal layer 223 is equal to the length of the long-side-region inner metal layer 224 in the second direction (y direction).
It should be noted that, as a whole, the long-side-region surface metal layer 223 and the short-side-region surface metal layer 221 are portions of the same diffusion layer (both surface diffusion layers) diffused out along two directions (the first direction and the second direction), and are respectively located on the long side and the short side, so for convenience of introduction and distinction of the long side and the short side, they are referred to as different names, and they are substantially two directions of the same L-shaped diffusion layer; similarly, the long-side region internal metal layer 224 and the short-side region internal metal layer 222 are also portions of the same diffusion layer (both internal diffusion layers) expressed in both directions. Correspondingly, the long L-shaped edge of the L-shaped step-shaped structure is used for connecting a core (core) area, the lengths of the replacement metal areas corresponding to the long L-shaped edges are all equal, the short L-shaped edge is used as a contact end/welding point (pad) connected with the control circuit, the surface layer of the replacement metal area corresponding to the short L-shaped edge is larger than the inner size, if the surface layer is compared with the inner replacement metal area integrally, the replacement metal area of the surface layer is L-shaped with a longer short edge, the inner replacement metal area is I-shaped, and the lengths of the long edges of the surface layer and the inner replacement metal area are equal (equal along the y direction); in other embodiments, the surface layer replacement metal area is "L-shaped" with a longer short side, and the inner replacement metal area is "L-shaped" with a shorter short side, the lengths of the long sides being equivalent.
In this embodiment, as shown in fig. 1 and fig. 2, two word line units 1 in a pair are separated by a gate line gap 3 and distributed in a staggered mirror image, the staggered positions are different by the height of one step, the height of one step is equal to the height of one stacked pair, the staggered direction is along a third direction (z direction), and the third direction is perpendicular to both the first direction and the second direction.
In this embodiment, the stack layer pair 12 includes a plurality of stack layer pairs formed of insulating materials, each stack layer pair includes a first stack layer material 121 and a second stack layer material 122, for example, the first stack layer material 121 is silicon oxide, and the second stack layer material 122 is silicon nitride.
The distribution of a plurality of word line cells or a plurality of word line cell pairs is described below with reference to the drawings. Fig. 6 is a top view (a) and a perspective view (b) of an L-shaped stepped word line structure including a plurality of word line units stacked along a first direction (z direction) and a perspective view of the L-shaped stepped word line structure with an enlarged detail. Fig. 7 is a schematic structural diagram of a three-dimensional memory including an L-shaped step-like word line structure shown in fig. 1, in which a connection between a logic control circuit and a word line is realized by contacting a connection hole to a short-side-area surface metal layer. Fig. 8 is a schematic view of the structure shown in fig. 7, taken along line A3-A3, with the circled portion a being a cross-sectional view in the x-direction corresponding to the short side of the L-shape.
In an embodiment, a plurality (two or more) of word line units may be sequentially connected along the first direction (x direction) and distributed in a step-like manner, that is, a plurality of word line units are included along the first direction (x direction), a word line terminal end of a previous word line unit in the plurality of word line units and a word line terminal end of a next word line unit in the plurality of word line units are distributed in a step-like manner, for example, four word line units distributed along the x direction are illustrated in fig. 1, wherein a connection relationship between two adjacent word line units is illustrated in fig. 2.
In this embodiment, taking the word line unit pair as an example, as shown in fig. 1 to fig. 3, at least two pairs of word line units are included along the first direction, as shown by a circled area a in fig. 1, a tail end of a word line leading-out end of a previous word line unit pair and a head end of a word line leading-out end of a next word line unit pair of two adjacent L-shaped word line unit pairs are distributed in a step shape. In each L-shaped word line unit pair, two word line units in pair are separated by a grid line gap and distributed in a staggered mirror image mode, and the dislocation is different by the height of one step.
In another embodiment, the word line units may also be stacked along the third direction (z direction) and distributed in a step-like manner along the second direction (y direction), two stacked word line units along the z direction as illustrated in (a) of fig. 6 and a plurality of word line units stacked along the third direction as illustrated in (b) of fig. 6 protrude outward in sequence along the second direction (y direction) to form a stack of the word line units distributed in a step-like manner, where the protruding direction refers to the negative y-axis direction illustrated in (b) of fig. 6, and the height difference h of the step is the height of one stack pair, in this embodiment, the height of one stack pair is the height of the silicon oxide/silicon nitride stack pair. Of course, the stacking in the z-axis corresponding to the plurality of word line unit pairs is similar to the stacking of two word line units in the up-down direction, and is not described here again. The word line cell pairs differ in that inside each word line cell pair, it is necessary to have the following layout: the two word line units in pairs are separated by the grid line gap and distributed in a staggered mirror image mode, and the dislocation is different by the height of one step.
Of course, in other embodiments, a combination of the two layout forms may also be adopted, that is, the plurality of word line units may be stacked along the third direction, the plurality of word line units stacked along the third direction sequentially protrude outward along the second direction (y direction), and the plurality of word line units are sequentially connected in the first direction and distributed in a step shape.
Referring to fig. 7 and 8, in the present embodiment, the solder point of the connection hole 4 for connecting the word line terminal to the logic control circuit is located in the short-side region surface metal layer 221 at a distance from the gate line gap 3 that is greater than the length of the short-side region internal metal layer 222.
In this embodiment, referring to fig. 2 to 5, the L-shaped step-like word line structure further includes: and the protective layer 11 covers among the plurality of L-shaped word line units 1 and above each word line unit 1, and the gate line gap 3 penetrates through the upper surface of the protective layer 11.
In summary, in the embodiment, the replacement metal region on the end surface layer of the L-shaped short-side step is arranged based on the gate line gap, and the size of the replacement metal region in the first direction (x direction) is larger than that of the replacement metal region inside the L-shaped short-side step, so that the position of the connection hole (SSCT) perpendicular to the plane can be located based on the gate line gap, and the SSCT is arranged at a position larger than the size of the replacement metal region inside the end surface layer of the L-shaped short-side step in the first direction, so that when the SSCT is connected with the replacement metal region on the end surface layer of the L-shaped short-side step, a plurality of stacked layer pairs in a stacked structure, such as a plurality of silicon oxide/silicon nitride stacked layer pairs, are arranged below the SSCT, and thus the insulating layer is arranged below the metal layer of each connection (contact) drop point, and therefore, under the condition that the etching selection ratio is not high enough, even if the etching is excessive, the phenomenon of word line short circuit does not occur.
Second embodiment
In a second exemplary embodiment of the present disclosure, a method for fabricating an L-shaped step-like word line structure is provided. This embodiment exemplifies how to fabricate the L-shaped step-like word line structure in the first embodiment.
Fig. 9 is a flowchart illustrating a method for fabricating an L-shaped step-like word line structure according to an embodiment of the present disclosure.
Referring to fig. 9, the method for manufacturing the L-shaped step-like word line structure of the present embodiment includes:
step S201: making a stepped laminated structure including a plurality of laminated pairs formed of an insulating material, each of the laminated pairs serving as a step;
in an embodiment of the present disclosure, the stepped lamination 12 protrudes outward along the first direction and/or the second direction.
"A and/or B" means that A alone or B alone or both A and B are included.
In this embodiment, the stack layer pair 12 includes a plurality of stack layer pairs formed of insulating materials, each stack layer pair includes a first stack layer material 121 and a second stack layer material 122, for example, the first stack layer material 121 is silicon oxide, and the second stack layer material 122 is silicon nitride.
Step S202: dividing the laminated structure into a plurality of areas, wherein the laminated structure of each area is used for forming an L-shaped word line unit;
in this embodiment, the long side of the L-shape is used to connect the core (core) area, the short side of the L-shape is used as the contact/pad (pad) for connecting the control circuit, and the design of the circuit of the core area and the SS terminal (step-shaped word line terminal, corresponding to the short side) needs to divide the area (block) by the selection of the top selection gate (select gate).
Step S203: processing the tail end of the surface step of the laminated structure of each area, so that the etching rate of the tail end of the surface step is higher than that of the structure below the tail end of the surface step along the first direction;
in some embodiments of the present disclosure, when the stacked structure comprises a stacked pair of silicon oxide and silicon nitride, the surface step end of the stacked structure of each region is processed in a manner that: and increasing the nitrogen concentration in the silicon nitride at the tail end of the surface step by means of ion implantation or selective deposition.
Of course, there are various forms of forming different etching rates, the wet etching method adopted in this embodiment is used in cooperation with the form of changing the ion concentration, in other embodiments, other regulation and control methods may also be adopted, and any method capable of realizing etching rate differentiation is within the protection scope of the present disclosure.
Step S204: etching the processed laminated structure to form a gate line gap, wherein the gate line gap extends along the second direction and the depth direction of the etching is vertical to the surface of the laminated structure;
the gate line gap 3 is formed between adjacent partitions or on the center line of the same partition to form a word line unit pair, and two word line units 1 in a pair are separated by the gate line gap 3 and distributed in a staggered mirror image. One side of the gate line slit (e.g., the left side in fig. 2) is tangent to the surface step of one of the stacked structures and penetrates the other step layers below, as shown in fig. 1 and 2.
Step S205: etching and hollowing a region, close to the gate line gap, of one of the lamination layers in each lamination layer pair based on the gate line gap;
along the first direction, since the end of the surface step is processed, the etching rate of the end of the surface step is higher than that of the structure located below the end of the surface step, and then after one of the stacked layers (for example, the stacked layers both including the second stacked material 122) in each stacked layer pair is etched and hollowed based on the gate line slit 3, the corresponding size of the etched region of the one of the stacked layers in the surface step is larger than that of the etched region of the structure directly below the one of the stacked layers, that is, the subsequently formed L-shaped short side corresponds to the other one;
along the second direction, the dimension corresponding to the etched region of the one of the stacked layers in the surface step is equal to the dimension corresponding to the etched region of the structure directly below the one of the stacked layers, that is, the L-shaped long side is formed.
Step S206: depositing a metal material in the hollowed area to obtain a replacement metal area, wherein the lead-out end of the word line corresponds to the surface metal layer of the short side area; forming a plurality of L-shaped word line units, wherein one long side of each L-shaped word line unit extends along the second direction and is adjacent to a gate line gap, one short side of each L-shaped word line unit extends along the first direction, and the short side of each L-shaped word line unit comprises a word line leading-out terminal;
in this embodiment, as shown in fig. 2 and fig. 3, the replacement metal region 11 includes a short-side-region surface metal layer 221 located on the surface and a short-side-region internal metal layer 222 located inside, in the first direction, the length of the short-side-region surface metal layer 221 is greater than that of the short-side-region internal metal layer 222, and the word line leading-out terminal corresponds to the short-side-region surface metal layer 221;
as shown in fig. 4 and 5, the replacement metal area 11 further includes a long-side-area surface metal layer 223 located on the surface and a long-side-area inner metal layer 224 located inside, and the length of the long-side-area surface metal layer 223 is equal to the length of the long-side-area inner metal layer 224 in the second direction.
In some embodiments of the present disclosure, before the step S204 of etching the processed stacked structure to form a gate line gap, the method further includes: a step of forming a protective layer; in this embodiment, step S203 is performed first, after the end of the surface step of the stacked structure in each region is processed, in order to form a mask or play a role in protecting the surface in the process of etching the gate line gap in the subsequent step S204, the protective layer 11 is formed first, and then the gate line gap 3 is formed in the stacked structure 12 based on a dry or wet etching process.
In some embodiments of the present disclosure, after the step S206 of obtaining the replacement metal region, the method further includes: and a step of forming a connection hole 4 for connecting a logic control circuit, as shown in fig. 7 and 8, where the connection hole 4 penetrates through the protective layer and is connected to a connection hole pad of the word line leading-out terminal, and the connection hole pad is located in a position, in the metal layer on the surface of the short side region, where a distance from the gap between the gate lines is greater than a length of the metal layer inside the short side region.
The manufacturing method of the embodiment further comprises other common steps or the execution sequence can be changed; of course, the method for manufacturing the L-shaped step-like word line structure is not limited to the embodiment, and any process capable of forming each component and the corresponding position relationship of the L-shaped step-like word line structure disclosed herein is within the scope of the present disclosure.
Third embodiment
In a third exemplary embodiment of the present disclosure, a three-dimensional memory is provided, including any one of the L-shaped stepped word line structures mentioned in the present disclosure.
In this embodiment, the three-dimensional memory includes: the logic control circuit is connected with the connection hole welding point position on the word line leading-out end of each word line unit 1 in the L-shaped step-like word line structure through a connection hole 4 in a corresponding mode, and the distance between the welding point of the connection hole and the gap of the grid line in the metal layer on the surface of the short edge area is larger than the length of the metal layer in the short edge area. Because the insulating layer is arranged below the welding point of the connecting hole, when the etching selection ratio of the connecting hole is not high enough, the phenomenon that the word line is short-circuited can be avoided even if the etching selection ratio is excessive.
In summary, the present disclosure provides an L-shaped step-shaped word line structure, a method for fabricating the same, and a three-dimensional memory, in which a replacement metal region on a surface layer of an end of an L-shaped short side step is arranged based on a gate line gap, and the size of the replacement metal region in a first direction (x direction) is larger than that of an inner replacement metal region, so that a location of a connection hole (SSCT) perpendicular to a plane can be located based on the gate line gap, and the SSCT is arranged at a location larger than that of the inner replacement metal region in the end of the L-shaped short side step in the first direction, so that when the SSCT is connected to the replacement metal region on the surface layer of the end of the L-shaped short side step, a plurality of stacked layer pairs in a stacked layer structure, such as a plurality of silicon oxide/silicon nitride stacked layer pairs, are arranged below the SSCT, and an insulating layer is arranged below a metal layer of each, even if the etching is excessive, the phenomenon of word line short circuit does not occur.
Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.
Furthermore, the word "comprising" or "comprises" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
Unless a technical obstacle or contradiction exists, the various features of the above-described embodiments of the present invention may be freely combined to form further embodiments, which are within the scope of the present invention.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (14)
1. An L-shaped step-like word line structure, comprising:
a plurality of L-shaped word line units, wherein one side of the long side of each L-shaped word line unit extends along the second direction (y direction) and is adjacent to a gate line gap, one side of the short side extends along the first direction (x direction) and the short side comprises a word line leading-out terminal;
the word line leading-out end is formed in a step-shaped laminated structure, the laminated structure comprises a plurality of laminated pairs formed by insulating materials, a region, close to a grid line gap, of one laminated layer in each laminated pair serves as a replacement metal region, the replacement metal region comprises a short-edge region surface metal layer located on the surface and a short-edge region internal metal layer located inside, in the first direction, the length of the short-edge region surface metal layer is larger than that of the short-edge region internal metal layer, and the word line leading-out end corresponds to the short-edge region surface metal layer; the word line leading-out end is used for connecting a connecting hole welding point of a logic control circuit and is positioned at a position, away from a grid line gap, in the metal layer on the surface of the short edge area, and the distance is larger than the length of the metal layer in the short edge area.
2. The L-shaped step-like word line structure of claim 1 wherein the replacement metal region further comprises a long side region surface metal layer on the surface and a long side region internal metal layer inside, the long side region surface metal layer having a length equal to the length of the long side region internal metal layer in the second direction.
3. The L-shaped step-like word line structure of claim 1, wherein a plurality of L-shaped word line units are sequentially connected along the first direction and distributed in a step-like manner.
4. The L-shaped step-like word line structure of claim 1, wherein a plurality of L-shaped word line units are stacked along the third direction and distributed in a step-like manner along the second direction.
5. The L-shaped step-like word line structure of any one of claims 1-4, wherein the plurality of L-shaped word line units is at least one pair of L-shaped word line units, two L-shaped word line units in the pair are separated by the gate line slit and distributed in a staggered mirror image, the staggered arrangement is different by a height of one step, the height of the one step is equal to the height of one stacked pair, the direction of the staggered arrangement is along a third direction (z direction), and the third direction is perpendicular to the first direction and the second direction.
6. The L-shaped step wordline structure of claim 1, further comprising: and the protective layer covers among the plurality of L-shaped word line units and above each word line unit, and the gate line gap penetrates through the upper surface of the protective layer.
7. The L-shaped step word line structure as claimed in claim 1, wherein the L-shaped word line unit long side is used to connect to a core (core) region.
8. A method for fabricating an L-shaped step-like word line structure as claimed in any one of claims 1 to 7, comprising:
making a stepped laminated structure including a plurality of laminated pairs formed of an insulating material, each of the laminated pairs serving as a step;
dividing the laminated structure into a plurality of areas, wherein the laminated structure of each area is used for forming an L-shaped word line unit;
processing the tail end of the surface step of the laminated structure of each area, so that the etching rate of the tail end of the surface step is higher than that of the structure below the tail end of the surface step along the first direction;
etching the processed laminated structure to form a gate line gap, wherein the gate line gap extends along the second direction and the depth direction of the etching is vertical to the surface of the laminated structure;
etching and hollowing a region, close to the gate line gap, of one lamination in each lamination pair based on the gate line gap, wherein the corresponding size of the etched region of the one lamination in the surface step is larger than that of the etched region of the structure under the surface step along the first direction;
depositing a metal material in the hollowed area to obtain a replacement metal area, wherein the replacement metal area comprises a short-edge area surface metal layer positioned on the surface and a short-edge area internal metal layer positioned inside, the length of the short-edge area surface metal layer is greater than that of the short-edge area internal metal layer in the first direction, and the word line leading-out end corresponds to the short-edge area surface metal layer;
and forming a plurality of L-shaped word line units, wherein one long side of each L-shaped word line unit extends along the second direction and is adjacent to one gate line gap, one short side of each L-shaped word line unit extends along the first direction, and the short side of each L-shaped word line unit comprises the word line leading-out terminal.
9. The method of claim 8, wherein when the stacked structure comprises a stacked pair of silicon oxide and silicon nitride, the top step end of the stacked structure of each region is processed by: and increasing the nitrogen concentration in the silicon nitride at the tail end of the surface step by means of ion implantation or selective deposition.
10. The method of claim 8, further comprising, before the step of etching the processed stack structure to form a gate line gap: and forming a protective layer.
11. The method of claim 8, further comprising, after the step of obtaining the replacement metal region: and forming a connecting hole for connecting the logic control circuit, wherein the connecting hole penetrates through the protective layer and is connected with a connecting hole welding point of the word line leading-out end in a position corresponding to the position of the connecting hole welding point, and the distance from the connecting hole welding point to the grid line gap in the metal layer on the surface of the short edge area is larger than the length of the metal layer in the short edge area.
12. The method for fabricating an L-shaped step-like word line structure according to claim 8, wherein the step-like stacked structure protrudes outward along the first direction and/or the second direction.
13. The method as claimed in claim 8, wherein the replacement metal region further comprises a long-side-region surface metal layer on the surface and a long-side-region internal metal layer inside, and the length of the long-side-region surface metal layer is equal to the length of the long-side-region internal metal layer in the second direction.
14. A three-dimensional memory comprising the L-shaped stepped word line structure of any one of claims 1-7.
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