A self-aligned secondary molding process method for preventing side wall deformation

Abstract

The present invention provides a self-aligned secondary molding process method for preventing sidewall deformation. The method comprises growing a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer, and a polysilicon layer sequentially from bottom to top on a through-hole layer. The polysilicon layer is used as a hard mask to define a pattern and the second silicon nitride layer is etched to the upper surface of the second silicon oxide layer, forming the second silicon nitride layer into multiple silicon nitride pattern structures. Sidewalls are formed on the sidewalls of the multiple silicon nitride pattern structures. The silicon nitride pattern structures within the sidewalls are removed. The second silicon oxide layer and the titanium nitride layer are etched using the sidewalls as a hard mask to form a titanium nitride pattern structure. The first silicon oxide layer and the first silicon nitride layer are etched using the titanium nitride pattern structure as a hard mask to pattern the first silicon oxide layer and the first silicon nitride layer. By integrating the composite film layers, the present invention achieves stress matching between the film layers at high temperatures, completely resolving sidewall tilt and achieving pattern definition for secondary molding.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a self-aligned secondary molding process method for preventing sidewall deformation. Background Art

[0002] After the design size of integrated circuits decreased to less than 40nm, the self-aligned secondary molding process was invented and used. Existing process integration suffers from significant metal line deformation. Analysis indicates that the film combination used in the primary molding process experiences stress mismatch at a high temperature of 530°C. After the sidewall etching process, the sidewall angle is approximately 87°, but the NDC (SiCN) at the bottom of the sidewall has significantly deformed. After wet removal of the core SiO2 layer within the sidewall, the stress is released, causing the sidewall to tilt significantly, at an angle of approximately 82°. This makes it impossible to accurately define the titanium nitride size below the sidewall in subsequent processes, which in turn affects the final metal line shape. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a self-aligned secondary molding process method for preventing sidewall deformation, so as to solve the problem of sidewall deformation caused by stress mismatch in the secondary molding process in the prior art.

[0004] To achieve the above-mentioned and other related objectives, the present invention provides a self-aligned secondary molding process method for preventing sidewall deformation, which at least comprises:

[0005] Step 1: growing a composite film layer on the through-hole layer; the composite film layer is sequentially composed of: a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer, and a polysilicon layer from bottom to top;

[0006] Step 2: using the polysilicon layer as a hard mask to define a pattern and etching the second silicon nitride layer to the upper surface of the second silicon oxide layer according to the defined pattern, so as to form the second silicon nitride layer into a plurality of silicon nitride pattern structures;

[0007] Step 3: forming sidewall spacers on the sidewalls of the plurality of silicon nitride pattern structures;

[0008] Step 4: removing the silicon nitride pattern structure in the sidewall;

[0009] Step 5: etching the second silicon oxide layer and the titanium nitride layer using the sidewall as a hard mask to form a titanium nitride pattern structure;

[0010] Step six: using the titanium nitride pattern structure as a hard mask to etch the first silicon oxide layer and the first silicon nitride layer to pattern the first silicon oxide layer and the first silicon nitride layer.

[0011] Preferably, the through-hole layer in step 1 comprises a plurality of through-holes, and a dielectric layer is filled between the through-holes.

[0012] Preferably, the first and second silicon oxide layers in step 1 are formed by chemical vapor deposition.

[0013] Preferably, in step 1, the temperature for forming the first and second silicon oxide layers by chemical vapor deposition is 400°C.

[0014] Preferably, the first and second silicon nitride layers in step 1 are formed by chemical vapor deposition.

[0015] Preferably, in step 1, the temperature for forming the first and second silicon nitride layers by chemical vapor deposition is 400°C.

[0016] Preferably, in step one, a diffusion furnace process is used to form the polysilicon layer.

[0017] Preferably, the sidewalls formed on the sidewalls of the silicon nitride graphic structure in step three are polysilicon sidewalls.

[0018] Preferably, the method for forming the polysilicon sidewalls in step three adopts a diffusion furnace process with a growth temperature of 530°C.

[0019] Preferably, in step four, a wet etching method is used to remove the silicon nitride pattern structure in the sidewall.

[0020] As described above, the self-aligned secondary molding process method for preventing side wall deformation of the present invention has the following beneficial effects: by reintegrating the film, the stress between each film layer at high temperature is matched, which completely solves the problem of side wall tilt and smoothly realizes the graphic definition of secondary molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a schematic structural diagram of the composite film layer on the through hole in the present invention;

[0022] Figure 2 It is a schematic structural diagram showing the process of forming a silicon nitride layer into a plurality of silicon nitride pattern structures in the present invention;

[0023] Figure 3 It is a schematic diagram showing the structure after a layer of polysilicon is deposited on a plurality of silicon nitride pattern structures in the present invention;

[0024] Figure 4 It is a schematic diagram showing the structure after sidewalls are formed on the sidewalls of multiple silicon nitride pattern structures in the present invention;

[0025] Figure 5 It is a schematic diagram showing the structure after the silicon nitride pattern structure in the sidewall is removed in the present invention;

[0026] Figure 6 Shown is a schematic structural diagram of the present invention after the first silicon oxide layer and the first silicon nitride layer are patterned;

[0027] Figure 7 A flow chart of the self-aligned secondary molding process for preventing sidewall deformation according to the present invention is shown. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] See also Figures 1 to 7 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0030] The present invention provides a self-aligned secondary molding process method for preventing side wall deformation, such as Figure 7 As shown, Figure 7 The flowchart of the self-aligned secondary molding process for preventing sidewall deformation of the present invention includes at least the following steps:

[0031] Step 1: growing a composite film layer on the through-hole layer; the composite film layer is sequentially composed of: a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer, and a polysilicon layer from bottom to top; Figure 1 As shown, Figure 1 The schematic diagram shows the structure of the composite film layer on the through hole in the present invention. The composite film layers grown on the through hole layer are, from bottom to top, the first silicon nitride layer 03, the first silicon oxide layer 04, the titanium nitride layer 05, the second silicon oxide layer 06, the second silicon nitride layer 07, and the polysilicon layer 08.

[0032] The present invention further comprises the through-hole layer of step 1 of this embodiment comprising a plurality of through-holes, with a dielectric layer filled between the through-holes. The through-hole layer in this embodiment is located on the substrate and comprises a plurality of through-holes 02 and a dielectric layer 02 located between the through-holes 01.

[0033] Furthermore, the first and second silicon oxide layers in step 1 of this embodiment are formed by chemical vapor deposition. Furthermore, the temperature for forming the first and second silicon oxide layers by chemical vapor deposition in step 1 of this embodiment is 400°C.

[0034] Furthermore, the first and second silicon nitride layers in step 1 of this embodiment are formed by chemical vapor deposition. Furthermore, the temperature for forming the first and second silicon nitride layers by chemical vapor deposition in step 1 of this embodiment is 400°C.

[0035] Furthermore, in the step 1 of the present embodiment, the polysilicon layer 08 is formed by using a diffusion furnace process.

[0036] Step 2: Using the polysilicon layer as a hard mask to define a pattern and etching the second silicon nitride layer to the upper surface of the second silicon oxide layer according to the defined pattern, forming the second silicon nitride layer into a plurality of silicon nitride pattern structures; Figure 2 As shown, Figure 2 The figure shows a schematic diagram of forming a silicon nitride layer into a plurality of silicon nitride pattern structures in the present invention. In step 2, the polysilicon layer 08 is used as a hard mask to define a pattern and the second silicon nitride layer 07 is etched according to the defined pattern to the upper surface of the second silicon oxide layer 06, thereby forming the second silicon nitride layer into a plurality of silicon nitride pattern structures 071.

[0037] Step 3: forming sidewalls on the sidewalls of the plurality of silicon nitride graphic structures; Figure 3 As shown, Figure 3 It is a schematic diagram showing the structure after a layer of polysilicon is deposited on multiple silicon nitride graphic structures in the present invention. Figure 4 As shown, Figure 4 The figure shows a schematic diagram of the structure after forming sidewalls on the sidewalls of multiple silicon nitride pattern structures in the present invention. Before forming the sidewalls in step 3, a layer of polysilicon 08 is deposited on the multiple silicon nitride pattern structures. The polysilicon 08 is then etched to form the sidewalls 081.

[0038] Furthermore, in the present invention, in step three of this embodiment, the sidewalls formed on the sidewalls of the silicon nitride graphic structure are polysilicon sidewalls.

[0039] Furthermore, in the present invention, the method for forming the polysilicon sidewalls in step three of this embodiment adopts a diffusion furnace process with a growth temperature of 530°C.

[0040] Step 4: removing the silicon nitride pattern structure in the sidewall; Figure 5 As shown, Figure 5It is a schematic diagram showing the structure after the silicon nitride pattern structure in the sidewall is removed in the present invention.

[0041] Furthermore, in the fourth step of the present embodiment, a wet etching method is used to remove the silicon nitride pattern structure in the sidewall.

[0042] Step 5: Using the sidewall as a hard mask, the second silicon oxide layer and the titanium nitride layer are etched to form a titanium nitride pattern structure; Step 5 is performed along the Figure 5 The sidewall 081 in the middle is etched downwards to etch the second silicon oxide layer 06 and the titanium nitride layer 05, so that the titanium nitride layer 05 is formed into the titanium nitride pattern structure;

[0043] Step 6: Using the titanium nitride pattern structure as a hard mask, the first silicon oxide layer and the first silicon nitride layer are etched to pattern the first silicon oxide layer and the first silicon nitride layer. Figure 6 As shown, Figure 6 The diagram shows the structure after the first silicon oxide layer and the first silicon nitride layer are patterned in the present invention. In step six, the first silicon oxide layer and the first silicon nitride layer are further etched downward along the titanium nitride pattern structure until the upper surface of the dielectric layer 02 is exposed. This forms a first silicon oxide pattern structure 041 and a first silicon nitride pattern structure 031. After etching along the titanium nitride pattern structure, the titanium nitride pattern structure is not completely consumed in this embodiment, so a portion of the titanium nitride pattern structure (i.e., the remaining titanium nitride pattern structure 051) remains on the first silicon oxide pattern structure 041.

[0044] In summary, the present invention achieves balanced stress between film layers at high temperatures by re-integrating the film, completely resolving the sidewall tilt issue and enabling smooth overmolding of pattern definition. Therefore, the present invention effectively overcomes the shortcomings of existing technologies and possesses high industrial value.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A self-aligned secondary molding process method for preventing sidewall deformation, characterized in that: At least: Step 1: growing a composite film layer on the through-hole layer; the composite film layer is sequentially composed of: a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer, and a polysilicon layer from bottom to top; Step 2: using the polysilicon layer as a hard mask to define a pattern and etching the second silicon nitride layer to the upper surface of the second silicon oxide layer according to the defined pattern, so as to form the second silicon nitride layer into a plurality of silicon nitride pattern structures; Step 3: forming sidewall spacers on the sidewalls of the plurality of silicon nitride pattern structures; Step 4: removing the silicon nitride pattern structure in the sidewall; Step 5: etching the second silicon oxide layer and the titanium nitride layer using the sidewall as a hard mask to form a titanium nitride pattern structure; Step six: using the titanium nitride pattern structure as a hard mask to etch the first silicon oxide layer and the first silicon nitride layer to pattern the first silicon oxide layer and the first silicon nitride layer.

2. The self-aligned secondary molding process for preventing sidewall deformation according to claim 1, wherein: The through-hole layer in step 1 includes a plurality of through-holes, and a dielectric layer is filled between the through-holes.

3. The self-aligned secondary molding process for preventing sidewall deformation according to claim 1, wherein: In step 1, the first and second silicon oxide layers are formed by chemical vapor deposition.

4. The self-aligned secondary molding process for preventing sidewall deformation according to claim 3, wherein: In step 1, the temperature for forming the first and second silicon oxide layers by chemical vapor deposition is 400°C.

5. The self-aligned secondary molding process for preventing sidewall deformation according to claim 1, wherein: In step 1, the first and second silicon nitride layers are formed by chemical vapor deposition.

6. The self-aligned secondary molding process for preventing sidewall deformation according to claim 5, characterized in that: In step 1, the temperature for forming the first and second silicon nitride layers by chemical vapor deposition is 400°C.

7. The self-aligned secondary molding process for preventing sidewall deformation according to claim 5, wherein: In step one, the polysilicon layer is formed using a diffusion furnace process.

8. The self-aligned secondary molding process for preventing sidewall deformation according to claim 1, wherein: The sidewalls formed on the sidewalls of the silicon nitride graphic structure in step three are polysilicon sidewalls.

9. The self-aligned secondary molding process for preventing sidewall deformation according to claim 8, wherein: The method for forming the polysilicon sidewalls in step 3 adopts a diffusion furnace process with a growth temperature of 530°C.

10. The self-aligned secondary molding process for preventing sidewall deformation according to claim 1, wherein: In step 4, the silicon nitride pattern structure in the sidewall is removed by wet etching.

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