CN111640757A

CN111640757A - Memory and forming method thereof

Info

Publication number: CN111640757A
Application number: CN202010209621.6A
Authority: CN
Inventors: 童宇诚; 张钦福
Original assignee: Fujian Jinhua Integrated Circuit Co Ltd
Current assignee: Fujian Jinhua Integrated Circuit Co Ltd
Priority date: 2020-03-23
Filing date: 2020-03-23
Publication date: 2020-09-08

Abstract

The invention provides a memory and a forming method thereof. The end parts of the word lines extend into the peripheral area, and the contact plugs are formed in the peripheral area and electrically connected with the end parts of the word lines, so that the space of the peripheral area can be fully utilized to prepare the contact plugs in the peripheral area, the size of each contact plug is increased, the contact plugs can be connected with the top surfaces of the word lines and the side walls of the word lines, and the contact area between the contact plugs and the word lines is greatly increased. Namely, the memory provided by the invention is beneficial to reducing the preparation difficulty of the contact plug and improving the connection performance between the contact plug and the word line.

Description

Memory and forming method thereof

Technical Field

The invention relates to the technical field of semiconductors, in particular to a memory and a forming method thereof.

Background

A Memory (e.g., a Dynamic Random Access Memory) generally has a Memory cell array including a plurality of Memory cells arranged in an array. And the memory also comprises a plurality of word lines, and each word line is electrically connected with the corresponding memory unit respectively so as to apply corresponding signals to each memory unit.

For each word line, it is usually necessary to form a corresponding contact plug to electrically extract each word line. However, as the size of the semiconductor device is continuously reduced and the arrangement density of the integrated circuit is continuously increased, the size of the contact plug is also reduced, which not only increases the difficulty in manufacturing the contact plug, but also causes the connection performance between the contact plug and the word line to be difficult to ensure.

Disclosure of Invention

The invention aims to provide a memory, which is used for improving a process window of a contact plug connected with a word line and improving the connection performance between the contact plug and the word line.

To solve the above technical problem, the present invention provides a memory, including:

the substrate is provided with a memory area and a peripheral area, and the peripheral area is positioned at the periphery of the memory area;

a plurality of word lines buried in the substrate, and formed in the memory region and extending into the peripheral region such that ends of the word lines are located in the peripheral region;

a contact plug formed in the peripheral region and extending into the substrate to electrically connect to an end of the word line, and the contact plug covers a top surface of the word line and also extends to cover at least one sidewall of the word line.

Optionally, the word line has two sidewalls opposite in a width direction, and the contact plug extends to cover at least one of the two sidewalls.

Optionally, the two opposite sidewalls include a first sidewall and a second sidewall, and an area of the contact plug covering the first sidewall is larger than an area of the contact plug covering the second sidewall.

Optionally, the contact plug has a first contact portion covering the first sidewall and a second contact portion covering the second sidewall, and a bottom position of the first contact portion is lower than a bottom position of the second contact portion.

Optionally, the contact plug includes a metal silicide layer covering a top surface of the word line and extending to cover a sidewall of the word line, and a first conductive layer covering the metal silicide layer, so that the metal silicide layer is spaced between the first conductive layer and the word line.

Optionally, the word line has a first end and a second end opposite to each other, and the first end and the second end of the word line are respectively located in the peripheral region on two opposite sides of the memory region; and in two adjacent word lines, a contact plug connected with one of the word lines is formed on the first end portion, and a contact plug connected with the other word line is formed on the second end portion.

Optionally, the memory has M word lines, M being a positive integer greater than 1; the contact plug connected with the Nth word line is formed on the second end part of the word line, the contact plug connected with the (N-1) th word line and the contact plug connected with the (N + 1) th word line are formed on the first end part of the word line, the contact plug connected with the (N-1) th word line and the contact plug connected with the (N + 1) th word line are staggered in the arrangement direction of the word lines, and N is a positive integer larger than 1 and smaller than M.

Optionally, a dielectric layer is further formed on the substrate in the peripheral region, and the contact plug penetrates through the dielectric layer to extend into the substrate.

Optionally, the word line is formed in a word line trench of the substrate, and a top of the word line is lower than a top of the word line trench; and the memory also comprises a shielding layer, the shielding layer is filled in the space above the word line groove and higher than the word line, and the contact plug also penetrates through the shielding layer to extend to the word line.

Another object of the present invention is to provide a method for forming a memory, including:

providing a substrate, wherein the substrate is provided with a memory area and a peripheral area, and the peripheral area is positioned at the periphery of the memory area;

forming a plurality of word lines in the substrate, the word lines being formed in the memory region and extending into the peripheral region such that ends of the word lines are located in the peripheral region;

forming a contact plug formed in the peripheral region, a bottom of the contact plug extending into the substrate to be electrically connected to an end of the word line, and the contact plug covering a top surface of the word line and also extending to cover at least one sidewall of the word line.

In the memory provided by the invention, the word lines further extend from the memory area to the peripheral area, so that the contact plugs can be formed in the peripheral area to realize the electrical connection between the contact plugs and the corresponding word lines. Because the contact plugs are formed in the relatively open peripheral region, on one hand, the space in the peripheral region can be fully utilized, the extra occupied space in the memory region is avoided, and on the other hand, the size of each contact plug is favorably increased. Based on this, be favorable to realizing that the contact plug extends in the deeper position of substrate promptly to make the contact plug not only can contact with the top surface of word line and be connected, and can also contact with the lateral wall of word line and be connected, greatly increased the area of contact between contact plug and the word line, effectively ensured the connection performance between contact plug and the word line. At this time, even if the contact plug has a large alignment deviation with respect to the word line, since the contact plug may also be in contact with the word line on the sidewall of the word line, it is still possible to ensure a sufficient contact area between the contact plug and the word line. Therefore, the memory provided by the invention is not only beneficial to reducing the preparation difficulty of the contact plug, but also can effectively improve the connection performance between the contact plug and the word line.

Furthermore, two contact plugs connecting two adjacent word lines can be distributed and formed on different sides of the memory region, so that the space between the adjacent contact plugs can be further increased, and the process window of the contact plugs can be increased to a greater extent.

Drawings

Fig. 1 is a layout structure of a memory according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the memory shown in FIG. 1 along the direction aa';

FIG. 3 is a cross-sectional view of a memory according to a second embodiment of the present invention;

FIG. 4 is a cross-sectional view of a memory according to a third embodiment of the present invention;

fig. 5 is a layout structure of a memory in the fourth embodiment of the present invention;

FIG. 6 is a flow chart illustrating a method for forming a memory according to an embodiment of the invention.

Wherein the reference numbers are as follows:

100-a substrate;

100A-memory region;

100B-peripheral zone;

200-word line;

200 a-word line trench;

300-contact plug;

310-a metal silicide layer;

320-a first conductive layer;

330-a second conductive layer;

400-a shielding layer;

500-a dielectric layer;

AA-active region;

h1 — first height position;

h2-second elevation position.

Detailed Description

The memory and the forming method thereof according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Example one

Fig. 1 is a layout structure of a memory according to a first embodiment of the present invention, and fig. 2 is a schematic cross-sectional view of the memory shown in fig. 1 in the direction aa'.

As shown in fig. 1 and fig. 2, the memory in the present embodiment includes: a substrate 100; a plurality of word lines 200 buried in the substrate 100; and a contact plug 300 electrically connected to the word line 200.

The substrate 100 has a memory area 100A and a peripheral area 100B, and the peripheral area 100B is located at the periphery of the memory area 100A. And a plurality of active areas AA are formed in the memory area 100A of the substrate 100, and are arranged in an array to form a memory cell array.

With continued reference to fig. 1, a plurality of the word lines 200 are sequentially arranged along a first direction (X direction), and each of the word lines 200 extends along a second direction (Y direction). Specifically, the word lines 200 are formed in the memory region 100A and extend into the peripheral region 100B, so that the ends of the word lines 200 are located in the peripheral region 100B. Further, the word line 200 intersects the corresponding active area AA in the memory area 100A for applying an electrical signal to the corresponding memory cell.

And the end of the word line 200 extends into the peripheral region 100B, so that the electrical extraction of the word line 200 can be realized through the end of the word line 200. Specifically, a contact plug 300 electrically connected to the word line 200 for applying an electrical signal to the word line 200 may be formed in the peripheral region 100B so as to be electrically connected to an end of the word line 200.

It should be noted that, since the contact plugs 300 may be formed in the peripheral region 100B, a larger preparation space may be provided for the contact plugs 300, on one hand, the space of the peripheral region 100B is effectively utilized; on the other hand, the size of the contact plug 300 is increased, the process window of the contact plug 300 can be increased, the precision of the formed contact plug 300 can be improved, and sufficient contact between the contact plug 300 and the word line 200 can be ensured.

Referring specifically to fig. 2, the contact plug 300 extends into the substrate 100 to electrically connect to the end of the word line 200, and the contact plug 300 covers the top surface of the word line 200 and also extends to cover at least one sidewall of the word line 200.

That is, in this embodiment, the contact plug 300 is not only in contact with the top surface of the word line 200, but also in contact with the sidewall of the word line 200, so that the contact area between the contact plug 300 and the word line 200 is greatly increased, the contact resistance between the contact plug 300 and the word line 200 can be effectively reduced, and the connection performance between the contact plug 300 and the word line 200 can be improved.

It should be noted that, since the contact plug 300 in the present embodiment has a larger width dimension (i.e., the width dimension of the contact plug 300 is larger than the width dimension of the word line 200), in this case, when the contact plug 300 is prepared, the contact plug 300 can have a larger alignment deviation, which is still beneficial to ensure that the contact plug 300 and the word line 200 can contact each other on the top surface and the sidewall, thereby reducing the difficulty in preparing the contact plug 300 and increasing the process window of the contact plug 300.

It is considered that the bottom position of the contact plug 300 is lower than the top position of the word line 200 so that the contact plug 300 can extend onto the sidewall of the word line 200. Specifically, the top position of the word line 200 corresponds to, for example, a first height position H1, and the bottom position of the contact plug 300 corresponds to, for example, a second height position H2, the second height position H2 being lower than the first height position H1.

Further, the sidewalls of the word line 200 covered by the contact plug 300 include, for example: at least one of two sidewalls of the word line 200 opposite in the width direction. In this embodiment, the contact plug 300 extends to cover two sidewalls of the word line 200 opposite to each other in the width direction.

As shown in fig. 2, the contact plug 300 includes a metal silicide layer 310 and a first conductive layer 320. Wherein the metal silicide layer 310 covers the top surface of the word line 200 and extends to cover the sidewalls of the word line 200; and, the first conductive layer 320 covers the metal silicide layer 310, so that the metal silicide layer 310 is spaced between the first conductive layer 320 and the word line 200. It is considered that the film layer of the contact plug 300 contacting the word line 200 is the metal silicide layer 310, which is advantageous for reducing the contact resistance between the contact plug 300 and the word line 200. Further, the thickness of the portion of the metal silicide layer 310 covering the top surface of the word line is greater than the thickness of the portion of the metal silicide layer 310 covering the sidewalls of the word line.

Further, the contact plug 300 further includes a second conductive layer 330, and the second conductive layer 330 covers the metal silicide layer 310 and covers a bottom surface and sidewalls of the first conductive layer 320. Specifically, the contact plug 300 is received in a contact window, the word line 200 is exposed in the contact window, the metal silicide layer 310 is formed on a surface of the word line 200 exposed in the contact window, the second conductive layer 330 covers a bottom wall and a sidewall of the contact window, and accordingly covers the metal silicide layer 310, and the first conductive layer 320 is formed on the second conductive layer 330 and fills the contact window.

In a specific embodiment, the word line 200 has a first end and a second end opposite to each other, and the first end and the second end of the word line 200 extend to the peripheral region 100B on two opposite sides of the memory region 100A in opposite directions, respectively, so that the first end and the second end of the word line 200 are located in the peripheral region 100B on two opposite sides of the memory region 100A, respectively. At this time, the contact plug 300 may be formed on the first end and/or the second end of the word line 200.

In the present embodiment, of the two adjacent word lines 200, the contact plug 300 connected to one of the word lines 200 is formed on the first end portion, and the contact plug 300 connected to the other word line 200 is formed on the second end portion. That is, in this embodiment, the contact plugs 300 connected to the adjacent word lines 200 are formed on different ends of the word lines 200 and further located on different sides of the memory region 100A, so that the contact plugs 300 on the two adjacent word lines 200 are staggered from each other. Thus, each contact plug 300 can be allowed to have a larger forming space, which is beneficial to realizing the preparation of the large-size contact plug 300.

Specifically, since the contact plugs 300 of the adjacent word lines 200 are respectively located at different ends of the word lines 200, the width of the contact plugs 300 may be further laterally extended along the width direction (i.e., the X direction) of the word lines, so that the width dimension of the contact plugs 300 is greater than the width dimension of the word lines 200, and at this time, the contact plugs 300 may cover not only the top surfaces of the word lines 200, but also the two opposite sidewalls of the word lines 200. In addition, the contact plug 300 is formed in the relatively open peripheral region 100B, so that the contact plug 300 may also be longitudinally expanded along the length direction of the word line (i.e., the Y direction), thereby further increasing the width dimension of the contact plug 300 in the Y direction.

In this embodiment, the cross-sectional shape of the contact plug 300 perpendicular to the height direction may be rectangular, and both the width dimension and the length dimension of the contact plug 300 may be further expanded, so as to improve the process window of the contact plug 300.

With continued reference to fig. 1, in the present embodiment, the plurality of contact plugs 300 formed in the peripheral region 100B on the same side of the memory region 100A may be aligned in the word line arrangement direction (i.e., the X direction). That is, the plurality of contact plugs 300 formed on the first end portions of the different word lines are aligned in the arrangement direction of the word lines, and the plurality of contact plugs 300 formed on the second end portions of the different word lines are also aligned in the arrangement direction of the word lines.

Optionally, a trench isolation structure (not shown) is further formed in the peripheral region 100B of the substrate 100, and the trench isolation structure may surround the memory region 100A to isolate the memory region 100A. At this time, the end of the word line 200 may extend into the trench isolation structure in the extending direction thereof, and the contact plug 300 may extend downward into the trench isolation structure to be connected to the end of the word line 200.

With continued reference to fig. 2, the word lines 200 are formed in the word line trenches 200A of the substrate 100, and in particular, the word line trenches 200A correspondingly extend from the memory region 100A into the peripheral region 100B. In this embodiment, the portion of the word line trench 200a located in the peripheral region 100B is opened in the trench isolation structure of the substrate.

And the word line 200 is filled in the word line trench 200a, and the top position of the word line 200 is lower than the top position of the word line trench 200 a. Based on this, the shielding layer 400 is further filled in the space above the word line trench 200a and above the word line 200, and the shielding layer 400 correspondingly covers the word line 200. At this time, the contact plug 300 connected to the word line 200 may correspondingly penetrate through the shielding layer 400 to extend to the word line 200.

Specifically, in the width direction of the word line 200, the width dimension of the contact plug 300 is greater than the width dimension of the shielding layer 400 and correspondingly greater than the opening dimension of the word line trench 200a in the width direction of the word line, so that the outer sidewall of the contact plug 300 extends outward from the word line trench to the outside of the word line trench.

In this embodiment, a dielectric layer 500 is further formed on the substrate 100, and the contact plug 300 correspondingly further penetrates through the dielectric layer 500. That is, the contact plug 300 sequentially penetrates through the dielectric layer 500 and the shielding layer 400 to reach into the word line 200.

Optionally, a width of a portion of the contact plug 300 located in the dielectric layer 500 is greater than a width of a portion of the contact plug 300 located in the substrate 100. Thus, the width of the top of the contact plug 300 is increased and the contact area of the top of the contact plug 300 is increased on the basis that the bottom of the contact plug 300 can be connected with the word line 200.

Example two

It should be noted that the contact plugs in the first embodiment cover two opposite sidewalls of the word line, and the coverage area covering the two opposite sidewalls is the same. However, unlike the first embodiment, the coverage areas of the contact plugs on the two sidewalls of the word line are different from each other in the present embodiment.

Fig. 3 is a schematic cross-sectional view of a memory according to a second embodiment of the invention. As shown in fig. 3, the word line 200 has two opposite first and second sidewalls in a width direction thereof; and, the contact plug 300 covers the top surface of the word line 200 and further extends to cover the first sidewall and the second sidewall, and the coverage area of the contact plug 300 on the first sidewall is different from the coverage area of the contact plug 300 on the second sidewall. For example, the area of the contact plug 300 covering the first sidewall is larger than the area of the contact plug 300 covering the second sidewall.

In this embodiment, the contact 300 has a first contact portion covering the first sidewall and a second contact portion covering the second sidewall, and the bottom position of the first contact portion is lower than the bottom position of the second contact portion, so that the first contact portion has a larger coverage area for the sidewall of the word line relative to the second contact portion.

Similarly, in the present embodiment, the contact plug 300 also includes a metal silicide layer 310, a second conductive layer 330, and a first conductive layer 320. Wherein a coverage area of the metal silicide layer 310 on the first sidewall is different from a coverage area of the metal silicide layer 310 on the second sidewall, and the second conductive layer 330 and the first conductive layer 320 sequentially cover the metal silicide layer 320.

EXAMPLE III

The contact plug in the first embodiment covers two opposite sidewalls of the word line. However, unlike the first embodiment, the contact plug in the present embodiment covers only one of the two opposite sidewalls of the word line.

Fig. 4 is a schematic cross-sectional view of a memory according to a third embodiment of the invention. As shown in fig. 4, the contact plug 300 covers the top surface of the word line 200 and further extends to cover a first sidewall of the word line or a second sidewall of the word line. It can be considered that the contact plug 300 in the present embodiment is offset with respect to the center of the word line 200, thereby assuming an asymmetric structure. For example, the contact plug 300 is offset with respect to the word line 200 in a direction toward the first sidewall; alternatively, the contact plug 300 is offset with respect to the word line 200 in a direction toward the second sidewall.

Further, the contact plug 300 may have a smaller offset with respect to the word line 200 toward one of the sidewalls, so that the width dimension of the portion of the contact plug 300 covering the top surface of the word line is the same as the width dimension of the word line (i.e., the contact plug 300 and the word line 200 have mutually aligned sidewalls); alternatively, the contact plug 300 is allowed to have a larger offset relative to the word line 200 toward one of the sidewalls, so that the width of the portion of the contact plug 300 covering the top surface of the word line is smaller than the width of the word line 200, and at this time, a portion of the shielding layer 400 still remains on the top surface of the word line 200 not covered by the contact plug.

For example, in the present embodiment, the contact plug 300 is offset toward the first sidewall relative to the word line 200 to cover the top surface of the word line 200 near the first sidewall and extend to cover the first sidewall of the word line 200, and at this time, a portion of the shielding layer 400 still remains on the top surface of the word line 200 near the second sidewall.

It should be appreciated that, since the contact plug 300 may extend to a deeper position in the substrate 100 to cover the sidewall of the word line 200, the contact plug 300 may have a larger alignment deviation, and the connection performance between the contact plug 300 and the word line 200 may still be ensured.

As shown in fig. 2 and 4, the contact plug 300 in the present embodiment also includes a metal silicide layer 310, a second conductive layer 330, and a first conductive layer 320, similar to the embodiment. However, unlike the first embodiment, in the present embodiment, the metal silicide layer 310 covers the top surface of the word line 200 and only extends to cover the first sidewall of the word line, or only extends to cover the second sidewall of the word line; the second conductive layer 330 and the first conductive layer 320 respectively cover the metal silicide layer 320. That is, the first conductive layer 320 is offset with respect to the word line 200 in a direction toward the first sidewall, or is offset with respect to the word line 200 in a direction toward the second sidewall.

Example four

Fig. 5 is a layout structure of a memory according to a fourth embodiment of the present invention, and as shown in fig. 5, the memory includes M word lines 200, where M is a positive integer greater than 1, and the M word lines 200 are sequentially arranged along a first direction (X direction).

Further, contact plugs connected to the nth word line are formed on the second end portions (not shown) of the word lines, and contact plugs 300 connected to the (N-1) th word line and contact plugs 300 connected to the (N + 1) th word line are formed on the first end portions of the word lines, where N is a positive integer greater than 1 and less than M. That is, similar to the embodiment, the contact plugs 300 on two adjacent word lines 200 in the embodiment are also formed on different ends of the word lines 200, respectively.

However, unlike the first embodiment, in the present embodiment, the contact plugs 300 located on the same end of the word line 200 (i.e., the contact plugs 300 located on the same side of the memory region 100A) are not aligned along the word line arrangement direction. Specifically, in the plurality of contact plugs 300 located on the same side of the memory region 100A, two adjacent contact plugs 300 are staggered from each other in the arrangement direction thereof, so that there is no portion facing each other in the arrangement direction of two adjacent contact plugs 300, and therefore the problem that the adjacent contact plugs 300 are easily bridged can be effectively improved, and the width dimension of the contact plugs 300 can be further increased.

In this embodiment, among the contact plugs 300 located on the same side of the memory region 100A, the contact plugs 300 spaced apart from each other are aligned in the arrangement direction. That is, the plurality of contact plugs 300 on the same side are aligned in two rows, respectively, and two adjacent contact plugs 300 arranged in one row are spaced apart from each other by another contact plug 300 arranged in the other row.

As shown in fig. 5, the cross-sectional shape of the contact plug 300 perpendicular to the height direction may be circular, elliptical, or the like. Of course, the cross-sectional shape of the contact plug 300 may be rectangular as shown in the first embodiment.

Based on the memory as described above, a method of forming the memory will be described in detail below. Fig. 6 is a flowchart illustrating a method for forming a memory according to an embodiment of the invention, and as shown in fig. 6, the method for forming a memory according to the embodiment includes the following steps.

Step S100, a substrate is provided, where the substrate has a memory region and a peripheral region, and the peripheral region is located at the periphery of the memory region. Referring specifically to fig. 1 to 4, a plurality of active regions AA may be formed in the memory region 100A of the substrate 100.

Step S200, forming a plurality of word lines in the substrate, wherein the word lines are formed in the memory region and extend into the peripheral region, so that end portions of the word lines are located in the peripheral region.

Referring to fig. 2 to 4, the method for forming the word line 200 includes: first, word line trenches 200A are formed in the substrate 100, and the word line trenches 200A are in the memory area 100A and pass through the corresponding active areas AA, and the end portions of the word line trenches 200A further extend into the peripheral area 100B; next, a conductive material is filled in the word line trench 200a to form the word line 200.

In this embodiment, the word line 200 does not fill the word line trench 200a, and based on this, after forming the word line 200, the method further includes: the shielding layer 400 is filled in the space above the word line trench 200a to cover the word line 200. Wherein, the material of the shielding layer 400 includes silicon nitride, for example.

Further, after the word line 200 is formed, the method further includes: a dielectric layer 500 is formed on the substrate 100, and the dielectric layer 500 correspondingly covers the shielding layer 400. The material of the dielectric layer 500 may be different from that of the shielding layer 400, for example, the material of the dielectric layer 500 may include silicon oxide.

Step S300, forming a contact plug formed in the peripheral region, wherein a bottom of the contact plug extends into the substrate to be electrically connected to an end of the word line, and the contact plug covers a top surface of the word line and also extends to cover at least one sidewall of the word line.

As shown in fig. 2 to 3, the contact plug 300 may extend to cover both sidewalls of the word line 200 opposite in the width direction, or the contact plug 300 may extend to cover only one sidewall of the word line 200.

Specifically, the method for forming the contact plug 300 includes the following steps, for example.

Step one, forming a contact window in the peripheral region, wherein the bottom of the contact window extends into the substrate 100 to expose the word line 200. Specifically, the bottommost position of the contact window is lower than the top position of the word line, so that at least part of the top surface of the word line 200 and at least part of the sidewall of the word line 200 are exposed in the contact window.

For example, as shown in fig. 2, the top surface of the word line 200 is exposed in the contact window, and two sidewalls of the word line 200 opposite to each other in the width direction are also exposed, wherein the two sidewalls of the word line 200 opposite to each other in the width direction are exposed in the contact window to the same depth; alternatively, as shown in fig. 3, the exposure depths of the two sidewalls of the word line 200 opposite in the width direction exposed in the contact window are different from each other; alternatively, as shown in fig. 4, the contact window exposes the top surface of the word line 200, and also exposes one of the sidewalls of the word line 200.

The contact window can be formed by utilizing a photoetching process and an etching process. Firstly, defining the pattern of the contact window by utilizing a photoetching process, and then copying the pattern of the contact window into the substrate by utilizing an etching process. It should be noted that, since the contact window is formed in the open peripheral region, it is advantageous to increase the process window of the contact window when the pattern of the contact window is defined by using the photolithography process. And, the contact window can extend in a deeper position of the substrate, so that the top surface of the word line 200 and the side wall of the word line 200 can be exposed at the same time, the exposed area of the word line 200 is greatly increased, and therefore, the photoetching process of the contact window can be allowed to have larger alignment deviation, and the preparation difficulty of the contact window is further reduced.

In a further scheme, two contact plugs connected to two adjacent word lines 200 are respectively formed on different sides of the memory region 100A, and two contact windows exposing two adjacent word lines 200 are correspondingly respectively formed on different sides of the memory region 100A. At this time, a larger space can be reserved between two adjacent contact windows located on the same side of the memory region 100A, which is beneficial to increasing the opening size of the contact windows and further increasing the process window of the contact windows.

Specifically, the method for copying the pattern of the contact window into the substrate 100 comprises the following steps: the dielectric layer 500 and the shielding layer 400 are sequentially etched to expose the word line 200. In an alternative scheme, the dielectric layer 500 and the shielding layer 400 may be formed by using different materials, so that during the etching process, different etching rates may be provided for the dielectric layer 500 and the shielding layer 400. For example, the etching rate of the dielectric layer 500 is greater than that of the shielding layer 400, so that the formed contact window is wide at the top and narrow at the bottom. That is, the opening size of the portion of the contact window located in the dielectric layer 500 is larger than the opening size of the portion of the contact window located in the shielding layer 400. Therefore, the width dimension of the top of the contact plug formed subsequently can be correspondingly increased.

In addition, in this embodiment, etching a portion of the substrate outside the word line trench 200a to expose the sidewall of the word line 200 is further included.

Step two, forming a conductive material in the contact window to form the contact plug 300. Specifically, the method for filling the conductive material in the contact window may include the following steps.

In step one, a metal silicide layer 310 is formed on the exposed top surface and sidewalls of the word line 200. The forming method of the metal silicide layer 310 includes, for example: preferentially depositing a metal material layer in the contact window, wherein the metal material layer covers the top surface and the side wall of the word line exposed in the contact window; next, a heat treatment is performed to react both the top surface and the sidewalls of the word line with the metal in the metal material layer, thereby forming the metal silicide layer 310.

Step two, forming a second conductive layer 330 on the bottom wall and the side wall of the contact window, wherein the second conductive layer 330 correspondingly covers the metal silicide layer 310;

step three, forming a first conductive layer 320 on the second conductive layer 330, and filling the contact window.

In summary, in the memory provided in this embodiment, since the end portions of the word lines extend into the peripheral region, the contact plugs can be formed in the peripheral region to be electrically connected to the end portions of the corresponding word lines. Therefore, the space in the peripheral area can be fully utilized to make more space for the memory area to accommodate the capacitor assembly, and the contact plugs are prepared in the peripheral area, so that the size of each contact plug is increased, the preparation difficulty of the contact plug is effectively reduced, and the process window of the contact plug is increased.

And the contact plug not only covers the top surface of the word line, but also extends to cover the side wall of the word line, so that the contact area between the contact plug and the word line is greatly increased, and the connection performance between the contact plug and the word line is effectively improved.

Furthermore, two contact plugs for connecting two adjacent word lines are respectively formed on different sides of the memory region, so that the distance between the adjacent contact plugs can be further increased, and the process window of the contact plugs can be further increased to a greater extent.

Furthermore, for a plurality of contact plugs located on the same side of the memory region, adjacent contact plugs may be staggered from each other, so that a greater size expansion of the contact plugs can be achieved.

It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.

It should be noted that, although the present invention has been described with reference to the preferred embodiments, the above embodiments are not intended to limit the present invention. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.

It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.

It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Further, implementation of the methods and/or apparatus of embodiments of the present invention may include performing the selected task manually, automatically, or in combination.

Claims

1. A memory, comprising:

2. The memory of claim 1, wherein the word line has two sidewalls opposite in a width direction, the contact plug extending to cover at least one of the two sidewalls.

3. The memory of claim 2, wherein the two opposing sidewalls include a first sidewall and a second sidewall, and wherein an area of the contact plug covering the first sidewall is larger than an area of the contact plug covering the second sidewall.

4. The memory according to claim 3, wherein the contact plug has a first contact portion covering the first sidewall and a second contact portion covering the second sidewall, and a bottom position of the first contact portion is lower than a bottom position of the second contact portion.

5. The memory of claim 1, wherein the contact plug comprises a metal silicide layer covering a top surface of the word line and extending over sidewalls of the word line and a first conductive layer covering the metal silicide layer such that the first conductive layer and the word line are spaced apart by the metal silicide layer.

6. The memory of claim 1, wherein the word line has opposite first and second ends, the first and second ends of the word line being located in the peripheral region on opposite sides of the memory region, respectively;

and in two adjacent word lines, a contact plug connected with one of the word lines is formed on the first end portion, and a contact plug connected with the other word line is formed on the second end portion.

7. The memory of claim 6, wherein the memory has M word lines, M being a positive integer greater than 1;

the contact plug connected with the Nth word line is formed on the second end part of the word line, the contact plug connected with the (N-1) th word line and the contact plug connected with the (N + 1) th word line are formed on the first end part of the word line, the contact plug connected with the (N-1) th word line and the contact plug connected with the (N + 1) th word line are staggered in the arrangement direction of the word lines, and N is a positive integer larger than 1 and smaller than M.

8. The memory of claim 1, wherein a dielectric layer is further formed on the substrate in the peripheral region, and the contact plugs extend through the dielectric layer to extend into the substrate.

9. The memory of claim 1, wherein the word line is formed in a word line trench of the substrate, and a top of the word line is lower than a top of the word line trench;

and the memory also comprises a shielding layer, the shielding layer is filled in the space above the word line groove and higher than the word line, and the contact plug also penetrates through the shielding layer to extend to the word line.

10. A method for forming a memory, comprising: