Deep trench isolation structure and its manufacturing method

Abstract

This invention provides a deep trench isolation structure, including a silicon substrate, on which a plurality of perforated deep trenches are formed in an isolation structure region. The spacing between adjacent deep trenches is within a predetermined range, and the spacing is less than the silicon thickness required for thermal oxidation to form an oxide layer in the deep trenches. An oxide layer is formed in the deep trenches, and gaps are formed on the oxide layer, with insulating material layers filling the gaps. The deep trench structure of this invention is designed as a reasonably spaced array of through-hole deep trenches, with the remaining silicon interconnected, eliminating the risk of collapse.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a deep trench isolation structure and its manufacturing method. Background Technology

[0002] Deep trench isolation is a widely used isolation technology for preventing crosstalk between integrated circuit devices. However, with increasing demands for device breakdown resistance, traditional deep trench isolation technology is no longer sufficient to meet these requirements.

[0003] Deep trench isolation technology emerged to address this need. For process friendliness, smaller strip trenches are formed through deep trench etching. The remaining silicon strips are then oxidized using a high-temperature thermal oxidation process (usually partial oxidation due to process limitations) to form the isolation dielectric. The higher the proportion of the isolation dielectric, the better the isolation effect.

[0004] See also Figure 1 Existing deep trench isolation systems are strip-shaped structures, and an excessively large aspect ratio can cause the remaining silicon pillars to collapse.

[0005] To solve the above problems, a novel deep trench isolation structure and its manufacturing method are needed. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a deep trench isolation structure and its manufacturing method, which solves the problem that in the prior art, deep trench isolation is a strip structure, and the excessive aspect ratio will cause the remaining silicon pillars to collapse.

[0007] To achieve the above and other related objectives, the present invention provides a deep trench isolation structure, comprising:

[0008] A silicon substrate, wherein a plurality of deep trenches in the form of holes are formed on the isolation structure region of the silicon substrate; wherein,

[0009] The spacing between two adjacent deep trenches is within a preset range, and the spacing is less than the silicon thickness required for thermal oxidation to form an oxide layer in the deep trench.

[0010] The oxide layer is formed in the deep trench, and gaps are formed on the oxide layer, which are filled with an insulating material layer.

[0011] Preferably, the deep trench is polygonal in shape.

[0012] Preferably, the deep trench is any one of a regular angle, a square, or a regular hexagon.

[0013] Preferably, the deep trench is any one of the following shapes: rectangle, isosceles triangle, or hexagon with each interior angle of 120°.

[0014] Preferably, the spacing between two adjacent deep trenches is equal.

[0015] Preferably, the insulating material layer is polycrystalline silicon or silicon dioxide.

[0016] The present invention also provides a deep trench isolation structure and a method for manufacturing the same, comprising:

[0017] Step 1: Provide a silicon substrate and form a plurality of hole-shaped deep trenches on the isolation structure region of the silicon substrate, wherein the spacing between two adjacent deep trenches is within a preset range, and the spacing is less than the silicon thickness required for thermal oxidation to form an oxide layer in the deep trenches;

[0018] Step 2: An oxide layer is formed on each of the deep trenches using a thermal oxidation method, and pores are formed between the oxide layers;

[0019] Step 3: Form an insulating material layer on the silicon substrate to fill the pores, and then grind the insulating material layer onto the silicon substrate.

[0020] Preferably, the deep trench in step one is polygonal in shape.

[0021] Preferably, the deep trench in step one is any one of a regular angle, a square, or a regular hexagon.

[0022] Preferably, the deep trench in step one is any one of the following shapes: rectangle, isosceles triangle, or hexagon with each interior angle of 120°.

[0023] Preferably, the spacing between two adjacent deep trenches in step one is equal.

[0024] Preferably, the insulating material layer in step three is polycrystalline silicon or silicon dioxide.

[0025] Preferably, the grinding method in step three is chemical mechanical planarization.

[0026] As described above, the deep trench isolation structure and its manufacturing method of the present invention have the following beneficial effects:

[0027] The deep trench structure of the present invention is designed as a reasonably spaced through-hole deep trench array, and the remaining silicon is interconnected, so there is no risk of it falling over. Attached Figure Description

[0028] Figure 1 The diagram shows the collapse of silicon strips in a deep trench isolation structure with a strip-shaped structure, as shown in the prior art.

[0029] Figure 2 The diagram shown is a top view of a deep trench according to one embodiment.

[0030] Figure 3 The diagram shows a cross-sectional view of a deep trench according to one embodiment;

[0031] Figure 4 The diagram shown is a top view of a deep trench after thermal oxidation, according to one embodiment.

[0032] Figure 5 The diagram shows a cross-sectional view of a deep trench after thermal oxidation, according to one embodiment.

[0033] Figure 6 This is a top view schematic diagram showing the filling of the gap in one embodiment;

[0034] Figure 7 The diagram shows a cross-sectional view after filling the gap, as shown in one embodiment.

[0035] Figure 8 The diagram shown is a schematic representation of the process flow of this invention. Detailed Implementation

[0036] The following specific examples illustrate the implementation 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 embodiments, and 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.

[0037] This invention provides a deep trench isolation structure, comprising:

[0038] A silicon substrate 101 has multiple perforated deep trenches 102 formed on its isolation structure region A1. Compared to the elongated deep trenches 102 in the prior art, the design of multiple perforated deep trenches 102 ensures that residual silicon remains interconnected after etching, eliminating the risk of collapse.

[0039] The spacing between two adjacent deep trenches 102 is within a preset range, and the spacing is less than the silicon thickness required to form an oxide layer by thermal oxidation in the deep trenches 102.

[0040] In one alternative implementation, the deep trench 102 is polygonal in shape.

[0041] In one alternative embodiment, the deep trench 102 can be any one of a regular angle, a square, or a regular hexagon.

[0042] In one alternative implementation, the deep trench 102 is any one of a rectangle, an isosceles triangle, or a hexagon with each interior angle of 120°.

[0043] In one alternative implementation, the spacing between two adjacent deep trenches 102 is equal.

[0044] For example, please refer to Figure 2 and Figure 3 It shows a plurality of hole-shaped deep trenches 102 formed on the isolation structure region A1 on the silicon substrate 101. The top view of the deep trenches 102 shows a hexagon with each interior angle of 120°, wherein the spacing between two adjacent deep trenches 102 is equal.

[0045] An oxide layer is formed in the deep trench 102, and gaps 103 are formed on the oxide layer. An insulating material layer 104 is filled in the gaps 103. The insulating material layer 104 can usually be formed by deposition and grinding.

[0046] In one alternative embodiment, the insulating material layer 104 is polycrystalline silicon or silicon dioxide. It should be noted that the insulating material layer 104 may also use other types of insulating materials, with polycrystalline silicon or silicon dioxide being preferred materials.

[0047] For example, please refer to Figure 4 and Figure 5 It shows a plurality of hole-shaped deep trenches 102 formed on an isolation structure region A1 on a silicon substrate 101. The top view of each deep trench 102 is a hexagon with an interior angle of 120°. When the spacing between adjacent deep trenches 102 is equal, an oxide layer is formed at the deep trenches 102 using a thermal oxidation process. Due to process limitations, gaps 103 are usually left. An insulating material layer 104 can then be filled into the gaps 103 to form a structure like... Figure 6 , Figure 7 The structure shown.

[0048] Please see Figure 8 The present invention also provides a deep trench 102 isolation structure and its manufacturing method, comprising:

[0049] Step 1: Provide a silicon substrate 101, and form multiple hole-shaped deep trenches 102 on the isolation structure region A1 of the silicon substrate 101. The spacing between two adjacent deep trenches 102 is within a preset range and is less than the silicon thickness required to form an oxide layer by thermal oxidation of the deep trenches 102. Compared with the long strip deep trenches 102 in the prior art, the design of multiple hole-shaped deep trenches 102 means that there is still residual silicon connected to each other after etching, and there is no risk of collapse.

[0050] In one alternative implementation, the deep trench 102 in step one is polygonal in shape.

[0051] In one alternative implementation, the deep trench 102 in step one can be any one of a regular angle, a square, or a regular hexagon.

[0052] In one alternative implementation, the deep trench 102 in step one can be any one of a rectangle, an isosceles triangle, or a hexagon with each interior angle of 120°.

[0053] In one alternative implementation, the spacing between two adjacent deep trenches 102 in step one is equal.

[0054] For example, please refer to Figure 2 and Figure 3 It shows a plurality of hole-shaped deep trenches 102 formed on the isolation structure region A1 on the silicon substrate 101. The top view of the deep trenches 102 shows a hexagon with each interior angle of 120°, wherein the spacing between two adjacent deep trenches 102 is equal.

[0055] Step 2: An oxide layer is formed on each deep trench 102 using a thermal oxidation method, and pores are formed between the oxide layers;

[0056] Step 3: Form an insulating material layer 104 that fills the pores on the silicon substrate 101, and then grind the insulating material layer 104 onto the silicon substrate 101.

[0057] In one optional embodiment, the insulating material layer 104 in step three is polycrystalline silicon or silicon dioxide. It should be noted that the insulating material layer 104 may also use other types of insulating materials, with polycrystalline silicon or silicon dioxide being preferred materials.

[0058] In one alternative implementation, the grinding method in step three is chemical mechanical planarization.

[0059] For example, please refer to Figure 4 and Figure 5 It shows a plurality of hole-shaped deep trenches 102 formed on an isolation structure region A1 on a silicon substrate 101. The top view of each deep trench 102 is a hexagon with an interior angle of 120°. When the spacing between adjacent deep trenches 102 is equal, an oxide layer is formed at the deep trenches 102 using a thermal oxidation process. Due to process limitations, gaps 103 are usually left. An insulating material layer 104 can then be filled into the gaps 103 to form a structure like... Figure 6 , Figure 7 The structure shown.

[0060] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0061] In summary, the deep trench structure of this invention is designed as a reasonably spaced array of through-hole deep trenches, with the remaining silicon cells interconnected, eliminating the risk of collapse. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0062] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A deep trench isolation structure, characterized in that, include: A silicon substrate, wherein a plurality of hole-shaped deep trenches are formed on an isolation structure region on the silicon substrate, such that the silicon substrate is interconnected between the plurality of deep trenches; wherein, The spacing between two adjacent deep trenches is within a preset range. An oxide layer is formed in the deep trench, and gaps are formed on the oxide layer. An insulating material layer is filled in the gaps. The shape of the deep trench is any one of an isosceles triangle or a hexagon with each interior angle of 120°. The spacing between two adjacent deep trenches is equal.

2. The deep trench isolation structure according to claim 1, characterized in that: The insulating material layer is polycrystalline silicon or silicon dioxide.

3. A method for manufacturing a deep trench isolation structure according to any one of claims 1 to 2, characterized in that, At least including: Step 1: Provide a silicon substrate and form a plurality of hole-shaped deep trenches on the isolation structure region of the silicon substrate, such that the silicon substrates between the plurality of deep trenches are interconnected, wherein the spacing between two adjacent deep trenches is within a preset range; Step 2: An oxide layer is formed on each of the deep trenches using a thermal oxidation method, and pores are formed between the oxide layers; Step 3: Form an insulating material layer on the silicon substrate to fill the pores, and then grind the insulating material layer onto the silicon substrate; The deep trenches in step one are any of the following shapes: isosceles triangles and hexagons with each interior angle of 120°; the spacing between any two adjacent deep trenches in step one is equal.

4. The manufacturing method of the deep trench isolation structure according to claim 3, characterized in that: The insulating material layer in step three is polycrystalline silicon or silicon dioxide.

5. The manufacturing method of the deep trench isolation structure according to claim 3, characterized in that: The grinding method in step three is chemical mechanical planarization.

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