Method for homogenizing oxide layer on fin structure surface

Abstract

The present invention provides a method for homogenizing the surface oxide layer of a fin structure, comprising: S1: amorphizing the top of the fin structure; S2: performing an oxidation process on the amorphized fin structure to form a surface oxide layer. Accordingly, the technical effect that can be achieved by the present invention is that after the top of the fin structure is amorphized, since there is no crystal plane effect of the oxidation process on the top of the fin, the oxidation rate on the entire surface of the fin structure is the same, so that a surface oxide layer with substantially the same thickness can be generated (the same on the top surface, corners, and sides of the fin structure), the uniformity of the oxide layer is improved, the reliability of the device is improved, and the possibility of leakage is reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor processing methods, and in particular to a method for homogenizing an oxide layer on the surface of a fin structure. Background Art

[0002] Fin Field-Effect Transistor (FinFET) is a three-dimensional device with a fin structure. Figure 1 As shown, a schematic structural diagram of a fin field effect transistor includes a fin structure (Fin) 01, a channel 02 located between adjacent fin structures 01, an oxide layer 03, a silicon nitride layer 04, and a shallow trench isolation layer (STI) 05 in the channel 02, the oxide layer 03, the silicon nitride layer 04, and the shallow trench isolation layer (STI) 05 are ground to expose the upper part 06 of the fin structure, and the upper part 06 of the fin structure has a top surface 07 and a corner 08 structure.

[0003] In the prior art, since silicon crystals have different oxidation rates at different crystal planes, generally, the oxidation rate is: silicon crystal plane (100)>silicon crystal plane (110)>silicon crystal plane (111), so, usually, the oxide layer formed by the in-situ steam oxidation process (ISSG) on the upper part of the fin structure will have a thickness at the corner of the fin that is less than the thickness of the top surface. The oxide layer is used as an insulating material to isolate the fin structure and the upper layer structure of the fin. However, the inconsistent thickness of the oxide layer will lead to reduced reliability of the device and leakage.

[0004] The problem in the prior art is that the oxide layer generated on the upper part of the fin has inconsistent thickness due to different oxidation rates of different crystal planes, which reduces the reliability of the device and causes leakage. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to improve the uniformity of the thickness of the oxide layer on the upper part of the fin.

[0006] In order to solve the above technical problems, the present invention provides a method for homogenizing the surface oxide layer of a fin structure, the purpose of which is to make the thickness of the surface oxide layer on the upper part of the fin structure consistent at the top and the corners, thereby improving the reliability of the device and reducing leakage.

[0007] In order to achieve the above object, the present invention provides a method for homogenizing an oxide layer on the surface of a fin structure, comprising:

[0008] S1: amorphization of the top of the fin structure;

[0009] S2: performing an oxidation process on the amorphized fin structure to form a surface oxide layer.

[0010] Preferably, before step S1, the method further comprises:

[0011] SP1: forming a pad oxide layer on a silicon substrate, forming a first hard mask layer on the pad oxide layer, patterning the first hard mask layer, and then etching to form a fin structure based on the patterned first hard mask layer;

[0012] SP2: depositing a first oxide layer on the sidewalls of the fin structure and the bottom of the grooves between the fin structures, and then depositing a second hard mask layer on the first oxide layer, the pad oxide layer, and the first hard mask layer;

[0013] SP3: depositing a shallow trench isolation layer, performing a first chemical mechanical polishing on the shallow trench isolation layer, and partially removing the shallow trench isolation layer until the first hard mask layer is exposed;

[0014] SP4: Remove the first hard mask layer.

[0015] Preferably, between steps S1 and S2, the method further comprises:

[0016] SM1: Perform a second chemical mechanical polishing on the shallow trench isolation layer to remove the pad oxide layer covering the fin structure - the first oxide layer, the second hard mask layer, and the shallow trench isolation layer until the fin structure is partially exposed to form a groove. At the bottom of the groove, there are shallow trench isolation layers, first oxide layers, and second hard mask layers that have not been removed.

[0017] Preferably, after step S2, the method further comprises:

[0018] SR1: Nitriding and annealing processes are used to drive nitrogen into the surface oxide layer and keep nitrogen in the surface oxide layer;

[0019] SR2: Polysilicon is deposited and patterned to form the gate structure.

[0020] Preferably, in step S1 , a top implantation method is used to amorphize the top of the fin structure to form an amorphized region on the top of the fin.

[0021] Preferably, the injected substance is neutral, and the injected substance includes one or more of silicon, hydrogen, helium, argon, xenon, and krypton.

[0022] Preferably, in step S2, an in-situ water vapor oxidation process is adopted to grow and form a surface oxide layer.

[0023] Preferably, the first hard mask layer and the second hard mask layer are silicon nitride;

[0024] After step SP4, it also includes:

[0025] SP5: removing the pad oxide layer between the first hard mask layer and the top of the fin structure;

[0026] SP6: depositing a new oxide layer by atomic layer deposition to form a new pad oxide layer on top of the fin structure to control the uniformity of the amorphization in step S1;

[0027] Between steps S1 and S2, the method further includes:

[0028] SM10: The shallow trench isolation layer, the new pad oxide layer, the first oxide layer, and the second hard mask layer are removed to the same depth until the fin structure is partially exposed to form a groove, and the shallow trench isolation layer, the second hard mask layer, and the first oxide layer that have not been removed exist at the bottom of the groove.

[0029] Preferably, in step SR1 , a decoupled plasma nitridation process is adopted, followed by a post-nitridation annealing process, to implant plasma nitrogen into the surface oxide layer of the fin structure.

[0030] Preferably, two corner edges of the top of the formed fin structure are arc-shaped.

[0031] Compared with the prior art, the present invention provides a method for homogenizing the surface oxide layer of a fin structure, comprising: S1: amorphizing the top of the fin structure; S2: performing an oxidation process on the amorphized fin structure to form a surface oxide layer. Accordingly, the technical effect that can be achieved by the present invention is that after the top of the fin structure is amorphized, since there is no crystal plane effect of the oxidation process on the top of the fin, the oxidation rate on the entire surface of the fin structure is the same, so that a surface oxide layer with substantially the same thickness can be generated (the same on the top surface, corners, and sides of the fin structure), the uniformity of the oxide layer is improved, the reliability of the device is improved, and the possibility of leakage is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A fin structure form of the prior art is shown.

[0033] Figures 2A to 2G A schematic diagram showing the structural evolution of some steps of an embodiment of a method for homogenizing an oxide layer on the surface of a fin structure provided by the present invention is shown.

[0034] Figure 3 It is shown that the thickness of the surface oxide layer at the top surface and corner of the fin structure manufactured by the method for homogenizing the surface oxide layer of the fin structure provided by the present invention is consistent, and the shape of the corner is an arc.

[0035] Description of Figure Numbers.

[0036] Existing technology:

[0037] 01 Fin structure

[0038] 02 Channel

[0039] 03 Oxide layer

[0040] 04 Silicon Nitride Layer

[0041] 05 Shallow Trench Isolation Layer

[0042] 06 Upper part of the fin structure

[0043] 07 Top

[0044] 08 Corner;

[0045] The present invention:

[0046] 100 Silicon substrate

[0047] 101 Pad Oxide Layer

[0048] 102 first hard mask layer

[0049] 103 Fin structure

[0050] 104 First Oxide Layer

[0051] 105 second hard mask layer

[0052] 106 Shallow Trench Isolation Layer

[0053] 107 slots

[0054] 108 Fin top amorphized area

[0055] 109 Surface oxide layer. DETAILED DESCRIPTION

[0056] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0057] See also Figure 2E and 2G , an embodiment of a method for homogenizing an oxide layer on the surface of a fin structure provided by the present invention.

[0058] This method includes: See Figure 2E As shown, step S1: amorphizing the top of the fin structure 103; see Figure 2G As shown, step S2 : performing an oxidation process on the amorphized fin structure 103 to form a surface oxide layer 109 .

[0059] See also Figures 2A to 2G FIG. 2 shows another embodiment of the method for homogenizing the oxide layer on the surface of the fin structure provided by the present invention.

[0060] See also Figure 2AAs shown, a pad oxide layer 101 is formed on a silicon substrate 100 , a first hard mask layer 102 is formed on the pad oxide layer 101 , the first hard mask layer 102 is patterned, and then a fin structure 103 (Fin) is formed by etching based on the patterned first hard mask layer 102 .

[0061] See also Figure 2B As shown, a first oxide layer 104 is deposited on the sidewalls of the fin structure 103 and the bottom of the grooves between the fin structures, and then a second hard mask layer 105 is deposited on the first oxide layer 104 , the pad oxide layer 101 , and the first hard mask layer 102 .

[0062] The first hard mask layer 102 and the second hard mask layer 105 are silicon nitride (SiN).

[0063] See also Figure 2B As shown, a shallow trench isolation layer 106 is deposited and a first chemical mechanical polishing (CMP) is performed on the shallow trench isolation layer 103. The shallow trench isolation layer 106 may be deposited by fluid chemical vapor deposition (FCVD).

[0064] See also Figure 2C As shown, the shallow trench isolation layer 106 is partially removed until the first hard mask layer 102 is exposed.

[0065] See also Figure 2D As shown, the first hard mask layer 102 is removed and the pad oxide layer 101 is exposed.

[0066] In order to improve the uniformity of the subsequent implantation process, another embodiment is provided in which the pad oxide layer 101 can be replaced.

[0067] The pad oxide layer 101 between the first hard mask layer 102 and the top of the fin structure 103 is removed.

[0068] A new oxide layer is deposited by atomic layer deposition (ALD) to form a new pad oxide layer on top of the fin structure to control the uniformity of amorphization of the silicon on top of the fin structure. Figure 2D As shown, the new pad oxide layer is also indicated by 101.

[0069] See also Figure 2E As shown, the top of the fin structure 103 is amorphized, forming a fin top amorphized region 108 .

[0070] Specifically, see Figure 2E As shown, a top implantation method (indicated by the arrow in the figure) is used to amorphize the top of the fin structure to form a fin top amorphized region 108 .

[0071] The injected material is neutral, and includes one or more of silicon (Si), hydrogen (H), helium (He), argon (Ar), xenon (Xe), and krypton (Kr). The electrically neutral injection will not have a significant impact on the mobility of carriers.

[0072] See also Figure 2F As shown, the shallow trench isolation layer 106 is subjected to a second chemical mechanical polishing (CMP) to remove the pad oxide layer 101-first oxide layer 104, the second hard mask layer 105, and the shallow trench isolation layer 106 covering the fin structure 103 until the fin structure 106 is partially exposed to form a groove 107, and the shallow trench isolation layer 106, the first oxide layer 104, and the second hard mask layer 105 that have not been removed exist at the bottom of the groove.

[0073] Based on another embodiment of generating a new pad oxide layer provided above, the shallow trench isolation layer 106, the new pad oxide layer 101, the first oxide layer 104, and the second hard mask layer 105 are all removed to the same depth until the fin structure 106 is partially exposed to form a groove 107, and the shallow trench isolation layer 106, the second hard mask layer 105, and the first oxide layer 104 that have not been removed exist at the bottom of the groove.

[0074] See also Figure 2G As shown, the amorphized fin structure 103 is oxidized to form a surface oxide layer 109. Since the top of the fin structure 103 has a fin top amorphized region 108, the effect of different oxidation rates of different crystal planes does not occur, so that the surface oxide layer 109 has a uniform thickness.

[0075] An in-situ steam generation (ISSG) process is used to grow the surface oxide layer 109 .

[0076] See also Figure 3 As shown, a schematic diagram of the top of a fin structure surface oxide layer 109 formed by using the method for homogenizing the surface oxide layer of a fin structure provided by the present invention is shown. In the figure, the thickness of the surface oxide layer 109 at the top surface and the corners is the same, and the two corner edges of the top of the fin structure finally formed are arc-shaped.

[0077] A nitridation and annealing process is used to drive nitrogen into the surface oxide layer and retain the nitrogen in the surface oxide layer.

[0078] Specifically, a decoupled plasma nitridation process (DPN) is used, followed by a post-nitridation annealing process (PNA), to inject plasma nitrogen into the surface oxide layer of the fin structure.

[0079] The surface oxide layer 109 is used to isolate the gate from the top of the fin structure.

[0080] Polysilicon is deposited and patterned to form a gate structure.

[0081] The above is a specific embodiment of the method for homogenizing the surface oxide layer of the fin structure provided by the present invention. Accordingly, the technical effect that can be achieved by the present invention is that after the top of the fin structure is amorphized, since there is no crystal plane effect of the oxidation process on the top of the fin, the oxidation rate on the entire surface of the fin structure is the same, so that a surface oxide layer with substantially the same thickness can be generated (the same on the top surface, corners, and sides of the fin structure), the uniformity of the oxide layer is improved, the reliability of the device is improved, and the possibility of leakage is reduced.

[0082] The above specific embodiments and accompanying drawings are only used to illustrate the technical solutions and technical effects of the present invention, and are not used to limit the present invention. Any person skilled in the art who is familiar with the technology can modify or change the above embodiments within the scope of the claims without violating the technical principles and spirit of the present invention, and all of them belong to the scope of protection of the present invention.

Claims

1. A method for homogenizing an oxide layer on a fin structure surface, characterized in that: Include: SP1: forming a pad oxide layer on a silicon substrate, forming a first hard mask layer on the pad oxide layer, patterning the first hard mask layer, and then etching to form a fin structure based on the patterned first hard mask layer; SP2: depositing a first oxide layer on the sidewalls of the fin structure and the bottom of the grooves between the fin structures, and then depositing a second hard mask layer on the first oxide layer, the pad oxide layer, and the first hard mask layer; SP3: depositing a shallow trench isolation layer, performing a first chemical mechanical polishing on the shallow trench isolation layer, and partially removing the shallow trench isolation layer until the first hard mask layer is completely exposed; SP4: removing the first hard mask layer; S1: A top vertical implantation method is used to amorphize the top of the fin structure to form an amorphized region on the top of the fin; the implanted material is electrically neutral; SM1: Perform a second chemical mechanical polishing on the shallow trench isolation layer to remove the pad oxide layer, the first oxide layer, the second hard mask layer, and the shallow trench isolation layer covering the fin structure until the fin structure is partially exposed to form a groove, and the shallow trench isolation layer, the first oxide layer, and the second hard mask layer that have not been removed exist at the bottom of the groove; S2: performing an oxidation process on the amorphized fin structure to form a surface oxide layer; SR1: Nitriding and annealing processes are used to drive nitrogen into the surface oxide layer and keep nitrogen in the surface oxide layer; SR2: Polysilicon is deposited and patterned to form the gate structure.

2. A method for homogenizing an oxide layer on a fin structure surface, characterized in that: Include: SP1: forming a pad oxide layer on a silicon substrate, forming a first hard mask layer on the pad oxide layer, patterning the first hard mask layer, and then etching to form a fin structure based on the patterned first hard mask layer; SP2: depositing a first oxide layer on the sidewalls of the fin structure and the bottom of the groove between the fin structures, and then depositing a second hard mask layer on the first oxide layer, the pad oxide layer, and the first hard mask layer; the first hard mask layer and the second hard mask layer are silicon nitride; SP3: depositing a shallow trench isolation layer, performing a first chemical mechanical polishing on the shallow trench isolation layer, and partially removing the shallow trench isolation layer until the first hard mask layer is completely exposed; SP4: removing the first hard mask layer; SP5: removing the pad oxide layer between the first hard mask layer and the top of the fin structure; SP6: depositing a new oxide layer by atomic layer deposition to form a new pad oxide layer on top of the fin structure; S1: A top vertical implantation method is used to amorphize the top of the fin structure to form an amorphized region on the top of the fin; the implanted material is electrically neutral; SM10: removing the shallow trench isolation layer, the new pad oxide layer, the first oxide layer, and the second hard mask layer to the same depth until the fin structure is partially exposed to form a groove, and the shallow trench isolation layer, the second hard mask layer, and the first oxide layer that have not been removed exist at the bottom of the groove; S2: performing an oxidation process on the amorphized fin structure to form a surface oxide layer; SR1: Nitriding and annealing processes are used to drive nitrogen into the surface oxide layer and keep nitrogen in the surface oxide layer; SR2: Polysilicon is deposited and patterned to form the gate structure.

3. The method for homogenizing the oxide layer on the surface of the fin structure according to claim 1 or 2, characterized in that: In step S1 , the injected substances include one or more of silicon, hydrogen, helium, argon, xenon, and krypton.

4. The method for homogenizing the oxide layer on the surface of a fin structure according to claim 1 or 2, characterized in that: In step S2, an in-situ water vapor oxidation process is adopted to grow and form a surface oxide layer.

5. The method for homogenizing the oxide layer on the surface of a fin structure according to claim 1 or 2, characterized in that: In step SR1 , a decoupled plasma nitridation process is adopted, followed by a post-nitridation annealing process, to implant plasma nitrogen into the surface oxide layer of the fin structure.

6. The method for homogenizing the oxide layer on the surface of a fin structure according to claim 1 or 2, characterized in that: The two corner edges of the top of the formed fin structure are in arc shape.

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