Method for improving gate filling of trench products

Abstract

The present invention provides a method for improving gate filling of trench products. A substrate is provided, and the substrate is covered with a hard mask layer. The hard mask layer and the substrate are both subjected to a first etching to form a first straight trench on the substrate, a second straight trench is formed in the hard mask layer, and a second straight trench with the same width as that of the first and second straight trenches is formed on the substrate. The widths of the first and second straight trenches are the first width. The hard mask layer is continuously etched by a second etching to increase the width of the second straight trench to a second width, and the substrate below it is exposed. The exposed substrate is etched by a third etching to form a third trench on the substrate so that the width above the second straight trench is increased to a third width, and the third trench is the third width. The entire hard mask layer is removed. A gate is deposited in the trench by deposition. After partial etching of the hard mask layer in the present invention, a straight trench with a slightly wider opening will be formed, and the gate will not close prematurely, so that cracks will not occur during the gate filling stage.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for improving gate filling of trench products. Background Art

[0002] For trench products, cracks will appear in the gate filling stage for 90° straight trenches; for some products, problems such as abnormal polysilicon depression morphology, in-plane stress abnormality, and variation of some parameters will occur due to gate cracks. Such products must adjust the trench to below 88.5° to ensure gate filling; compared with straight trench products, inclined trench products sacrifice the area of the mesa region, which is not conducive to the alignment control of contact holes for small linewidth products, and the saturation voltage drop performance of the products will also be affected.

[0003] Therefore, a new method for filling the gate of trench products is needed to ensure the filling effect of the gate and improve the product quality without sacrificing the mesa region. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for improving gate filling of trench products, which is used to solve the problems in the prior art that for trench products, cracks will appear in the gate filling stage for 90° straight trenches; compared with straight trench products, inclined trench products sacrifice the area of the mesa region, which is not conducive to the alignment control of contact holes for small linewidth products, and the saturation voltage drop performance of the products will also be affected.

[0005] To achieve the above object and other related objects, the present invention provides a method for improving gate filling of trench products, including:

[0006] Step 1: Provide a substrate covered with a hard mask layer.

[0007] Step 2: Etch the hard mask layer and the substrate to form a second straight trench in the hard mask layer and a first straight trench penetrating through the second straight trench on the substrate. The widths of the first and second straight trenches are a first width.

[0008] Step 3: Continue to etch the hard mask layer to increase the width of the second straight trench to a second width, and expose the substrate below it.

[0009] Step 4: Etch the exposed substrate to increase the width above the second straight trench to a third width.

[0010] Step 5: Remove the entire hard mask layer.

[0011] Step 6: Deposit the trench to form a gate.

[0012] Preferably, the substrate in Step 1 is a silicon substrate.

[0013] Preferably, the material of the hard mask layer in step one is any one of titanium nitride, silicon nitride, and silicon dioxide.

[0014] Preferably, the method for etching the hard mask layer and the substrate in step two is dry etching.

[0015] Preferably, the method for etching the hard mask layer in step three is wet etching.

[0016] Preferably, the ratio of the second width to the first width in step three is 1.05 to 1.15.

[0017] Preferably, the method for etching the exposed substrate in step four is dry etching.

[0018] Preferably, the ratio of the third width to the first width in step four is 1.1 to 1.5.

[0019] Preferably, the hard mask layer is removed by wet etching in step five.

[0020] Preferably, the material for depositing the trench in step six is polysilicon.

[0021] Preferably, the material for depositing the trench in step six is a metal material.

[0022] Preferably, the metal material is any one of nickel, nickel-manganese alloy, nickel-chromium alloy, and nickel-molybdenum-iron alloy.

[0023] As described above, the method for improving the gate filling of trench products in the present invention has the following beneficial effects:

[0024] After partial etching of the hard mask layer in the present invention, a straight trench with a slightly wider opening will be formed, and the gate will not close prematurely, so there will be no cracks during the gate filling stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It shows a schematic flow chart of the method of the present invention;

[0026] Figure 2 It shows a schematic diagram of the substrate of the present invention;

[0027] Figure 3 It shows a schematic diagram of the substrate after forming a straight trench of the present invention;

[0028] Figure 4 It shows a schematic diagram after continuing to etch the hard mask layer of the present invention;

[0029] Figure 5 It shows a schematic diagram after forming a third trench of the present invention;

[0030] Figure 6 Shown is a schematic diagram after the gate of the present invention is deposited. Detailed implementation manners

[0031] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] Please refer to Figure 1 , the present invention provides a method for improving the filling of the gate 12 of a trench product, including:

[0033] Step 1, please refer to Figure 2 , provide a substrate 10, and the substrate 10 is covered with a hard mask layer 11;

[0034] In a possible implementation manner, the material of the substrate 10 in Step 1 is a silicon substrate.

[0035] In a possible implementation manner, the material of the hard mask layer 11 in Step 1 is any one of titanium nitride, silicon nitride, and silicon dioxide.

[0036] Step 2, please refer to Figure 3 , etch the hard mask layer 11 and the substrate 10, form a second straight trench 111 in the hard mask layer 11, and form a first straight trench 101 penetrating the second straight trench 111 on the substrate 10. The widths of the first and second straight trenches (101, 111) are the first width;

[0037] In a possible implementation manner, the method for etching the hard mask layer 11 and the substrate 10 in Step 2 is dry etching. Since dry etching is isotropic etching, the angles of the first straight trench 101 and the second straight trench 111 can be 90 degrees, which is convenient for subsequent filling of the gate 12.

[0038] Step 3, please refer to Figure 4 , continue to etch the hard mask layer 11 to increase the width of the second straight trench 111 to the second width, and expose the substrate 10 below it;

[0039] In a possible implementation manner, the method for etching the hard mask layer 11 in Step 3 is wet etching. By controlling the wet etching time, since the etching rate at the edge of the second straight trench 111 is relatively fast, a part of the second straight trench 111 can be etched away.

[0040] In a possible implementation, the ratio of the second width to the first width in step three is 1.05 to 1.15, which facilitates the subsequent etching of the exposed substrate 10.

[0041] Step four, please refer to Figure 5 , etch the exposed substrate 10 so that the width above the second straight groove 111 increases to a third width;

[0042] In a possible implementation, the method of etching the exposed substrate 10 in step four is dry etching.

[0043] In a possible implementation, the ratio of the third width to the first width in step four is 1.1 to 1.5, so as to form a larger opening above the first straight groove, and the gate 12 will not close prematurely during the subsequent filling, so that there will be no cracks during the gate 12 filling stage.

[0044] Step five, remove the entire hard mask layer 11;

[0045] In a possible implementation, the method of removing the entire hard mask layer 11 in step five is: using wet etching to remove the hard mask layer 11.

[0046] Step six, please refer to Figure 6 , deposit a trench to form a gate.

[0047] In a possible implementation, the material of the gate 12 in step six is polysilicon.

[0048] In a possible implementation, the material of the gate 12 in step six is a metal material.

[0049] In a possible implementation, the material of the gate 12 in step six is at least one of nickel, nickel-manganese alloy, nickel-chromium alloy, and nickel-molybdenum-iron alloy.

[0050] It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0051] In summary, after partial etching of the hard mask layer in the present invention, straight grooves with a slightly wider opening will be formed, and the gate will not close prematurely, so that there will be no cracks during the gate filling stage. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0052] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for improving gate filling of trench products, characterized in that, it at least includes: Step 1: Provide a substrate covered with a hard mask layer; Step 2: Etch the hard mask layer and the substrate to form a second straight trench in the hard mask layer and a first straight trench penetrating through the second straight trench on the substrate, and the widths of the first and second straight trenches are the first width; Step 3: Continue to etch the hard mask layer to increase the width of the second straight trench to a second width, and the ratio of the second width to the first width is 1.05 to 1.15, and the substrate below it is exposed; Step 4: Etch the exposed substrate to increase the width above the second straight trench to a third width, and the ratio of the third width to the first width is 1.1 to 1.5; Step 5: Remove the entire hard mask layer; Step 6: Deposit the trench to form a gate.

2. The method for improving gate filling of trench products according to claim 1, characterized in that: The substrate in Step 1 is a silicon substrate.

3. The method for improving gate filling of trench products according to claim 1, characterized in that: The material of the hard mask layer in Step 1 is any one of titanium nitride, silicon nitride, and silicon dioxide.

4. The method for improving gate filling of trench products according to claim 1, characterized in that: The method for etching the hard mask layer and the substrate in Step 2 is dry etching.

5. The method for improving gate filling of trench products according to claim 1, characterized in that: The method for etching the hard mask layer in Step 3 is wet etching.

6. The method for improving gate filling of trench products according to claim 1, characterized in that: The method for etching the exposed substrate in Step 4 is dry etching.

7. The method for improving gate filling of trench products according to claim 1, characterized in that: The hard mask layer is removed by wet etching in Step 5.

8. The method for improving gate filling of trench products according to claim 1, characterized in that: The material for depositing the trench in Step 6 is polysilicon.

9. The method for improving gate filling of trench products according to claim 1, characterized in that: The material for depositing the trench in Step 6 is a metal material.

10. The method for improving gate filling of trench products according to claim 9, characterized in that: The metal material is any one of nickel, nickel-manganese alloy, nickel-chromium alloy, and nickel-molybdenum-iron alloy.

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