Word line layout and method for forming the same

Abstract

The present disclosure discloses a word line layout and a method for forming the same. The word line layout includes: a first word line group located on a substrate and including a plurality of L-shaped first word lines, each first word line having a first segment and a second segment connected to each other, wherein the first segment extends along a first direction, the second segment extends along a second direction, and the first direction is perpendicular to the second direction; a second word line group located on the substrate and including a plurality of L-shaped second word lines, each second word line having a first segment and a second segment connected to each other, wherein the first segment extends along the first direction, the second segment extends along the second direction, wherein the first word line group and the second word line group are arranged in parallel and symmetric to each other along a symmetry axis parallel to the second direction; and an I-shaped third word line disposed outside the first word line group and the second word line group and extending along the first direction and crossing the symmetry axis.

Description

Technical Field

[0001] The present invention relates to semiconductor technology, and particularly to a word line layout and a method for forming the same. Background Art

[0002] Due to the advantages of high density, low cost, rewritability, and electrically erasable properties, flash memory has become the mainstream of non-volatile memory devices in recent years and is widely used in various portable electronic products, such as notebook computers, digital cameras, mobile phones, game consoles, and other related portable electronic products. In order to increase the element density in the flash memory device and improve its overall performance, the manufacturing technology of dynamic random access memory devices is continuously striving for miniaturization of element sizes.

[0003] In semiconductor manufacturing processes, various components are often patterned through photolithography and etching processes. However, when the element size continues to shrink, many challenges arise. For example, when forming small-sized semiconductor structures, the patterning process (such as Self-Align Double Patterning (SADP)) environment may have an adverse impact on the semiconductor structure, thereby reducing the device reliability or yield.

[0004] Although existing flash memories and forming methods generally meet the requirements, they are not satisfactory in all aspects. Therefore, there is still a need to improve flash memory devices and forming methods to overcome the problems caused by element size reduction, improve process tolerance, and reduce process costs. Summary of the Invention

[0005] An embodiment of the present invention provides a word line layout, including: a first word line group located on a substrate and including a plurality of L-shaped first word lines, each first word line having a first segment and a second segment connected to each other, wherein the first segment extends along a first direction, the second segment extends along a second direction, and the first direction is perpendicular to the second direction; a second word line group located on the substrate and including a plurality of L-shaped second word lines, each second word line having a first segment and a second segment connected to each other, wherein the first segment extends along the first direction, the second segment extends along the second direction, wherein the first word line group and the second word line group are arranged in parallel and symmetric to each other along a symmetry axis parallel to the second direction; and an I-shaped third word line disposed outside the first word line group and the second word line group and extending along the first direction and crossing the symmetry axis.

[0006] An embodiment of the present invention provides a method for forming a word line layout, including: providing a substrate; forming a mask layer on the substrate; patterning the mask layer to form a patterned mask layer, including a plurality of L-shaped first masks, a plurality of L-shaped second masks, and a T-shaped third mask, wherein the L-shaped first masks and the L-shaped second masks are arranged side by side and symmetric to each other, and some of the T-shaped third masks are disposed between the L-shaped first masks and the L-shaped second masks; forming a plurality of spacers on the sidewalls of the patterned mask layer; and removing the patterned mask layer and leaving the spacers, wherein the spacers form the word line layout as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Embodiments of the present invention can be best understood from the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the dimensions of the various elements may be arbitrarily enlarged or reduced to clearly illustrate the features of the embodiments of the present invention.

[0008] Figure 1 FIG. is a top view showing a word line layout according to some embodiments of the present invention.

[0009] Figure 2 FIG. is a top view showing a partial word line layout according to some embodiments of the present invention.

[0010] Figures 3 to 5 FIG. is a top view showing a word line layout according to some embodiments of the present invention.

[0011] Figure 6A FIG. is a top view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0012] Figure 6B FIG. is a schematic cross-sectional view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0013] Figure 6C FIG. is a partial top view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0014] Figure 7 FIG. is a schematic cross-sectional view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0015] Figure 8A FIG. is a top view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0016] Figure 8B FIG. is a schematic cross-sectional view showing an intermediate stage of forming a word line layout according to some embodiments of the present invention.

[0017] Figure 9FIG. 0 is a cross-sectional schematic view showing a word line layout according to some embodiments of the present invention.

[0018] Figure 10 and Figure 11 FIG. 1 is a top view showing a word line layout according to some embodiments of the present invention.

[0019] Figure 12 FIG. 2 is a cross-sectional schematic view showing a word line layout according to some embodiments of the present invention.

[0020] Reference numerals:

[0021] 10, 20: Word line layout

[0022] 100: Substrate

[0023] 101: First word line

[0024] 101C, 102C: Connection line segment

[0025] 101P1: First segment of the first word line

[0026] 101P2: Second segment of the first word line

[0027] 102: Second word line

[0028] 102P1: First segment of the second word line

[0029] 102P2: Second segment of the second word line

[0030] 103: Third word line

[0031] 104: Protective layer

[0032] 110: Patterned mask layer

[0033] 111: First mask

[0034] 111P1: First part of the first mask

[0035] 111P2: Second part of the first mask

[0036] 112: Second mask

[0037] 112P1: First part of the second mask

[0038] 112P2: Second part of the second mask

[0039] 113: Third mask

[0040] 113P1: First part of the third mask

[0041] 113P2: Second part of the third mask

[0042] 114: Spacer material layer

[0043] 114S: Spacer

[0044] G1: First word line group

[0045] G2: Second word line group

[0046] S: Axis of symmetry

[0047] X: Second direction

[0048] Y: First direction

[0049] D1, D2, D3: Spacing

[0050] W1, W2, W3: Spacing

[0051] W4, W5, W6: Width Detailed implementation manners

[0052] Figures 1 to 3 is a top view showing a word line layout according to some embodiments of the present invention. Referring to Figure 1 , the word line layout 10 includes: a substrate 100, a first word line group G1, a second word line group G2, and an I-shaped third word line 103. The first word line group G1 is located on the substrate 100 and includes a plurality of L-shaped first word lines 101. The second word line group G2 is located on the substrate 100 and includes a plurality of L-shaped second word lines 102. The first word line group G1 and the second word line group G2 are arranged in parallel and symmetric to each other along an axis of symmetry S parallel to the second direction X. The I-shaped third word line 103 is disposed outside the first word line group G1 and the second word line group G2, and extends along the first direction Y and crosses the axis of symmetry S. In some embodiments, all the word lines in the word line layout 10 are symmetric along the axis of symmetry S. It should be understood that the number of word lines shown in the drawings is only for example, and is not intended to limit the embodiments of the present invention, and both ends of the word lines can extend to connect with other components, or one end of the word line can extend to connect with other components.

[0053] Figure 2 Further shows Figure 1 a partial schematic view of the word line layout 10 of Figure 2, each first word line 101 has a first segment 101P1 and a second segment 101P2 that are connected to each other, where the first segment 101P1 extends along a first direction Y, the second segment 101P2 extends along a second direction X, and the first direction Y is perpendicular to the second direction X. Similarly, each second word line 102 has a first segment 102P1 and a second segment 102P2 that are connected to each other, where the first segment 102P1 extends along the first direction Y and the second segment 102P2 extends along the second direction X. In some embodiments, the above-mentioned type-I third word line 103 being disposed outside the first word line group G1 and the second word line group G2 means that the type-I third word line 103 is disposed on one side of the first word line group G1 and the second word line group G2 in the opposite direction of the second direction X (i.e., the -X direction). According to some embodiments of the present invention, the first segment 101P1 and the second segment 101P2 of the first word line group G1 that are connected to each other are connected to each other at a position adjacent to the axis of symmetry S, and the first segment 102P1 and the second segment 102P2 of the second word line group G2 that are connected to each other are also connected to each other at a position adjacent to the axis of symmetry S. Referring to the first figure, in these embodiments, the position where the first segment 101P1 and the corresponding second segment 101P2 of the first word line group G1 are connected to each other moves away from the axis of symmetry S as the first word line 101 moves away from the third word line 103, and the position where the first segment 102P1 and the corresponding second segment 102P2 of the second word line group G2 are connected to each other moves away from the axis of symmetry S as the second word line 102 moves away from the third word line 103.

[0054] Referring again to Figure 1 and Figure 2, in some embodiments, in the first word line group G1, the pitches between adjacent first word lines 101 in the first direction Y or the second direction X are equal, and in the second word line group G2, the pitches between adjacent second word lines 120 in the first direction Y or the second direction X are equal. Specifically, in the first word line group G1, adjacent first segments 101P1 have the same pitch W1, and adjacent second segments 101P2 have the same pitch W2. Since the first word line group G1 and the second word line group G2 are symmetric with respect to the symmetry axis S, in the second word line group G2, adjacent first segments 102P1 also have the same pitch W1, and adjacent second segments 102P2 also have the same pitch W2. According to some embodiments of the present invention, the pitch W1 is greater than 20 nm, and the pitch W2 is greater than 20 nm. And in other embodiments, the adjacent first segments 101P1 in the first word line group G1 may have different pitches and the adjacent second segments 101P2 may also have different pitches. Since the first word line group G1 and the second word line group G2 are symmetric with respect to the symmetry axis S, in the second word line group G2, the pitches of the adjacent first segments 102P1 and the pitches of the adjacent second segments 102P2 are the same as the pitches of the adjacent first segments 101P1 and the adjacent second segments 101P2 in the symmetric first word line group G1, respectively.

[0055] In some embodiments, the pitch W3 between the third word line 103 and the first word line group G1 and the second word line group G2 is greater than or equal to the pitch W1 between two adjacent first segments 101P1 among these first word lines 101 and the pitch W1 between two adjacent first segments 102P1 among these second word lines 102. In one embodiment, the pitch W3 may be greater than the pitch W1 and the pitch W1 is greater than 20 nm. In this case, the third word line 103 may not be shown in the partial top view of the word line layout because it is relatively far from the first word line group G1 and the second word line group G2. In other embodiments, among the first word lines 101, the pitch W1 between two adjacent first segments 101P1 is greater than the pitch W2 between two adjacent second segments 101P2, and among the second word lines 102, the pitch W1 between two adjacent first segments 102P1 is greater than the pitch W2 between two adjacent second segments 102P2.

[0056] Specifically, in the word line layout 10, the third word line 103 disposed outside the first word line group G1 and the second word line group G2 can prevent the edges of the first word line group G1 and the second word line group G2 from being in an isolated environment. As described above, this can improve the process tolerance or yield, and can prevent the first word line group G1 and the second word line group G2 from breaking or necking down during the process. In a further embodiment, the distance W3 between the third word line 103 and the first word line group G1 and the second word line group G2, or the line segment distances W1 or W2 in the first word line group G1 and the second word line group G2 can be adjusted to achieve a symmetric, uniform, or dense word line layout, so as to improve the process tolerance or yield and prevent word line breakage or necking down under different process conditions or design requirements.

[0057] Referring to Figure 2 , the first word line 101 can have a connecting segment 101C to connect the first segment 101P1 and the second segment 101P2, and the second word line 102 can have a connecting segment 102C to connect the first segment 102P1 and the second segment 102P2. In Figure 2 's example, the connecting segments 101C and 102C are straight lines. In other embodiments, the connecting segments 101C and 102C are curves, as Figure 3 shown. Or the first segment 101P1 and the second segment 101P2 of the first word line 101 can be directly connected, and the connection between the first segment 102P1 and the second segment 102P2 of the second word line 102 can be directly connected without the connecting segments 101C and 102C, as Figure 4 shown.

[0058] Referring to Figure 5 , the word line layout 10 can include a plurality of protective layers 104 disposed on the first segment 101P1 of the first word line 101 and the first segment 102P1 of the second word line 102. In some embodiments, the material of the protective layer 104 includes undoped silicon. In other embodiments, the protective layer 104 is also disposed on the third word line 103. In some embodiments, the materials of the first word line 101, the second word line 102, and the protective layer 104 can include: carbon, silicon oxynitride, nitride, oxide, oxide-nitride-oxide (ONO), polysilicon, cobalt, cobalt silicide (CoSi2), metal, and impedance material. In some embodiments, the materials of the first word line 101 and the second word line 102 are different from the material of the protective layer 104.

[0059] Figure 6A and Figure 8A are top views showing intermediate stages of forming the word line layout according to some embodiments of the present invention. Figure 6B , Figure 7 , and Figure 8BAccording to some embodiments of the present invention, a cross-sectional schematic diagram showing an intermediate stage of forming a word line layout is illustrated. Figure 6B is Figure 6A a cross-sectional schematic diagram of the structure in Figure 6A along the straight line AA. Referring to Figure 6B and Figure 6A , a substrate 100 is provided, a mask material layer is formed on the substrate 100 and patterned to form a patterned mask layer 110. As

[0060] shown, the patterned mask layer 110 includes a plurality of L-shaped first masks 111, a plurality of L-shaped second masks 112, and a T-shaped third mask 113. The aforementioned plurality of L-shaped first masks 111 and the plurality of L-shaped second masks 112 are arranged side by side and symmetric to each other, and some of the T-shaped third masks 113 are disposed between the aforementioned plurality of L-shaped first masks 111 and the L-shaped second masks 112. It should be understood that the number of masks shown in the figure is only for illustration and is not intended to limit the present invention.

[0061] Figure 6C According to some embodiments, a partial schematic diagram of the patterned mask layer 110 is illustrated. To simplify the figure for convenience of explanation, only the T-shaped third mask 113 and a set of symmetric L-shaped first masks 111 and L-shaped second masks 112 are shown. Referring to Figure 6C, each L-shaped first mask 111 has a first part 111P1 and a second part 111P2 that are connected to each other. The first part 111P1 extends along the first direction Y, and the second part 111P2 extends along the second direction X. Each L-shaped second mask 112 has a first part 112P1 and a second part 112P2 that are connected to each other. The first part 112P1 extends along the first direction Y, and the second part 112P2 extends along the second direction X. And the L-shaped first mask 111 and the L-shaped second mask 112 are symmetric with respect to the axis of symmetry S parallel to the second direction X. The T-shaped third mask 113 includes a first part 113P1 and a second part 113P2 that are connected to each other. The first part 113P1 is disposed outside the L-shaped first mask 111 and the L-shaped second mask 112, extends along the first direction Y and crosses the axis of symmetry S, and the second part 113P2 is disposed on the axis of symmetry S and extends along the second direction X. Here, the outside means that the first part 113P1 of the T-shaped third mask 113 is disposed on one side of the L-shaped first mask 111 and the L-shaped second mask 112 in the opposite direction of the second direction X (i.e., the -X direction). According to some embodiments of the present invention, the patterned mask layer 110 is a symmetric structure and has an odd number of masks. For example, in Figure 6A , the patterned mask layer 110 may include a plurality of L-shaped first masks 111, a plurality of L-shaped second masks 112, and one T-shaped third mask 113. Because the plurality of L-shaped first masks 111 and the plurality of L-shaped second masks 112 are symmetric with respect to the axis of symmetry S, the number of L-shaped first masks 111 (for example, n) is the same as the number of L-shaped second masks 112, and their sum is a multiple of 2 (2n), and plus one T-shaped third mask 113. Therefore, the number of masks in the patterned mask layer 110 is odd (2n + 1).

[0062] Referring to Figure 6A and Figure 6C , in some embodiments, the distance D3 between the first part 113P1 of the T-shaped third mask 113 and the plurality of L-shaped first masks 111 and L-shaped second masks 112 is equal to the distance D1 between two adjacent first parts 111P1 among the plurality of L-shaped first masks 111 and the distance D1 between two adjacent first parts 112P1 among the plurality of L-shaped second masks 112. In some embodiments, the distance D2 between two adjacent second parts 111P2 among the plurality of L-shaped first masks 111 and the distance D2 between two adjacent second parts 112P2 among the plurality of L-shaped second masks 112 are less than the aforementioned distance D1. In Figure 6AIn some of the illustrated embodiments, the spacing D1 is greater than 20 nm, the spacing D2 is greater than 20 nm, and the spacing D3 is greater than 20 nm. In some embodiments, the width W4 of the first portion 111P1 of the L-shaped first mask 111 and the first portion 112P1 of the L-shaped second mask 112 is equal to the aforementioned spacing D3 and the width W6 of the first portion 113P1 of the T-shaped third mask 113. In some embodiments, the width W4 of the first portion 111P1 of the L-shaped first mask 111 and the first portion 112P1 of the L-shaped second mask 112 is greater than the width W5 of the second portion 111P2 of the L-shaped first mask 111 and the second portion 112P2 of the L-shaped second mask 112. In Figure 6C some of the illustrated embodiments, the width W4 is greater than 20 nm, the width W5 is greater than 20 nm, and the width W6 is greater than 20 nm. According to some embodiments of the present invention, the T-shaped third mask 113 is designed to be wider in the middle and narrower on both sides. For example, referring to Figure 6C , the width of the middle portion of the T-shaped third mask 113 in the second direction X ranges between W6 and W7 (where the width W7 is greater than W6, and the width W7 can be greater than 30 nm), which is greater than the width W6 of the first portion 113P1 of the T-shaped third mask 113 on both sides. The aforementioned configuration can enable the device to obtain a larger current in the low resistance state (LRS) and a smaller current value in the high resistance state (HRS).

[0063] Next, referring to Figure 7 , a conformal deposition spacer material layer 114 is deposited on the substrate 100 and on the top surface and sidewalls of the patterned mask layer 110. The material of the spacer material layer 114 includes: oxide, nitride, or polysilicon. The deposition process of the spacer material layer 114 can include: chemical vapor deposition, physical vapor deposition, atomic layer deposition, spin coating, etc.

[0064] Referring to Figure 8A and Figure 8B , Figure 8B is Figure 8A a cross-sectional schematic view of the structure in Figure 8AAs shown, spacers 114S are formed on the sidewalls of the L-shaped first mask 111, the L-shaped second mask 112, and the T-shaped third mask 113. In some embodiments, the etching process may include: reactive ion etching (RIE), neutral beam etching (NBE), inductively coupled plasma etching, other suitable etching processes, or a combination of the foregoing.

[0065] Referring to Figure 1 and Figure 9 , the patterned mask layer 110 is removed and the spacers 114S are left to form the word line layout 10 as shown in Figure 1 . Figure 9 FIG. Figure 1 is a cross-sectional schematic view of the word line layout 10 along line AA as shown. In some embodiments, the foregoing etching process may be used to remove the patterned mask layer 110, and a strip process, an ashing process, or a combination of the foregoing may also be used.

[0066] The method for forming a word line layout according to an embodiment of the present invention provides a patterned mask layer with symmetry, so that the desired spacers (or word lines) are not in an isolated environment during the process, which can avoid breakage or necking of the desired spacers during the process, thereby improving the performance and reliability of the device. For example, referring to Figure 8A , the spacers on the sidewalls of the T-shaped third mask 113 away from the L-shaped first mask 111 and the L-shaped second mask 112 can prevent the spacers on the sidewalls of the T-shaped third mask 113 close to the L-shaped first mask 111 and the L-shaped second mask 112 from being in an isolated environment during the process, so as to avoid breakage or necking caused by different process conditions in the isolated environment. In some embodiments, the spacers on the sidewalls of the T-shaped third mask 113 away from the L-shaped first mask 111 and the L-shaped second mask 112 may also be referred to as auxiliary spacers, and this auxiliary spacer corresponds to the third word line 103 in the word line layout 10 formed after removing the patterned mask layer 110.

[0067] The method for forming a word line layout according to an embodiment of the present invention also provides a symmetrically patterned mask layer with an odd number of masks (such as the embodiment shown in Figure 6A ), so that the desired spacers are not in an isolated environment or an asymmetric structure, and also has the foregoing technical effects.

[0068] In some embodiments, after removing the patterned mask layer 110 to form the word line layout 10 as shown in Figure 1 , the third word line 103 may be removed to form as shown in Figure 10The shown word line layout 20 is similar in configuration to the word line layout 10, where the word line layout 20 does not include the third word line 103. In some embodiments, a plurality of protective layers 104 can be formed on the first segment 101P1 of the L-shaped first word line 101 and on the first segment 102P1 of the L-shaped second word line 102 of the word line layout 20, as Figure 11 and Figure 12 shown Figure 12 is Figure 11 a schematic cross-sectional view of the word line layout 20 along the straight line AA as shown. In some embodiments, Figure 12 is Figure 5 a schematic cross-sectional view of the word line layout 10 along the straight line AA as shown. In addition to the aforementioned effects, the protective layer 104 in these embodiments can protect the underlying components or serve as a mask in subsequent process stages.

[0069] In summary, the embodiments of the present invention provide a word line layout, including a symmetric word line layout, which can avoid word line breakage or necking during the process and improve device reliability, process tolerance, or yield. The embodiments of the present invention also provide a method for forming a word line layout, including forming a symmetric patterned mask layer, which can provide a non-divergent environment during the patterning process to avoid word line breakage or necking, and has the effect of improving process tolerance.

Claims

1. A word line layout, characterized in that, Comprising: A first word line group located on a substrate and including a plurality of L-shaped first word lines, Each first word line has a first segment and a second segment connected to each other, wherein the first segment extends along a first direction, the second segment extends along a second direction, and the first direction is perpendicular to the second direction; A second word line group located on the substrate and including a plurality of L-shaped second word lines, Each second word line has a first segment and a second segment connected to each other, wherein the first segment extends along the first direction and the second segment extends along the second direction, Wherein the first word line group and the second word line group are arranged side by side and symmetric with respect to a symmetry axis parallel to the second direction; An I-shaped third word line disposed outside the first word line group and the second word line group, extending along the first direction and crossing the symmetry axis; And A plurality of protective layers disposed on the plurality of first segments of the plurality of first word lines and the plurality of second word lines.

2. The word line layout according to claim 1, characterized in that, The plurality of first segments and the plurality of second segments of the first word line group and the second word line group that are connected to each other are connected to each other at positions adjacent to the symmetry axis.

3. The word line layout according to claim 2, characterized in that, The positions where the plurality of first segments and the plurality of second segments are connected to each other are away from the symmetry axis as the plurality of first word lines and the plurality of second word lines are away from the third word line.

4. The word line layout according to claim 1, characterized in that, The material of the plurality of protective layers includes silicon.

5. The word line layout according to claim 1 or 2, characterized in that, The word line layout is symmetric with respect to the symmetry axis.

6. A method for forming a word line layout, characterized in that Comprising: Providing a substrate; Forming a mask layer on the substrate; Patterning the mask layer to form a patterned mask layer including a plurality of L-shaped first masks, a plurality of L-shaped second masks, and a T-shaped third mask, wherein the plurality of L-shaped first masks and the plurality of L-shaped second masks are arranged side by side and symmetric with respect to each other, and a part of the T-shaped third mask is disposed between the plurality of L-shaped first masks and the plurality of L-shaped second masks; Forming a plurality of spacers on the sidewalls of the patterned mask layer; And Removing the patterned mask layer and leaving the plurality of spacers, wherein the plurality of spacers form a word line layout as described in claim 1, and a plurality of protective layers are formed on the plurality of first segments of the plurality of first word lines and the plurality of second word lines.

7. The method for forming the word line layout according to claim 6, wherein In the plurality of L-shaped first masks, each first mask has a first part and a second part connected to each other, wherein the first part extends along a first direction, the second part extends along a second direction, and the first direction is perpendicular to the second direction; In the plurality of L-shaped second masks, each second mask has a first part and a second part connected to each other, wherein the first part extends along the first direction and the second part extends along the second direction, and the plurality of L-shaped first masks and the plurality of L-shaped second masks are symmetric with respect to a symmetry axis parallel to the second direction; and The T-shaped third mask includes a first part and a second part connected to each other, wherein the first part is disposed outside the plurality of L-shaped first masks and the plurality of L-shaped second masks, extends along the first direction and crosses the symmetry axis, and the second part is disposed on the symmetry axis and extends along the second direction.

8. The method for forming the word line layout according to claim 6 or 7, characterized in that, Further comprising removing the type-I third word line after removing the patterned mask layer.

9. The method for forming the word line layout according to claim 6 or 7, characterized in that, The patterned mask layer has an odd number of masks.

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