Fuse structure, storage unit and method for manufacturing fuse structure

Abstract

The present invention proposes a fuse structure, a storage unit and a method for manufacturing the fuse structure, wherein the fuse structure comprises: an oxide layer; a polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer sequentially stacked in the oxide layer, wherein the first through hole is configured as a fuse through hole and is arranged between the first metal layer and the second metal layer; a groove, which is arranged in the oxide layer and is arranged around the first metal layer, the first through hole, and the second metal layer, wherein the groove comprises a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer. The present invention can improve the reliability of the fuse structure and thus improve the reliability of the storage unit because the groove is arranged in the oxide layer of the fuse structure.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and more specifically, to a fuse structure, a storage unit and a method for manufacturing the fuse structure. Background Art

[0002] OTP (One-time Programmable Memory Cell) is a commonly used technology in integrated circuits. This technology does not require additional layers or process manufacturing steps to achieve precision adjustment or customer customization of chips after they leave the factory. Its basic principle is to adjust the chip by destroying metal fuses, polysilicon fuses, breaking through oxide layers, or capturing charges through floating gates.

[0003] In the prior art, destroying polysilicon fuses or metal fuses is the most commonly used technical means. However, since destroying polysilicon fuses or metal fuses requires a large current, each bit of storage unit requires a larger size of burning MOS tube. Therefore, the size of the chip will increase and the cost will become higher.

[0004] In recent years, through-hole fuses or through-hole fuses have been proposed, and the current required for programming can be much smaller than that of polysilicon fuses or metal fuses (about one order of magnitude smaller under the same process). Therefore, the size of the MOS tube required for programming each bit storage unit will also be much smaller, and the chip size can be reduced.

[0005] refer to Figure 1 , Figure 1 A schematic diagram of the structure of a conventional storage unit. Figure 2 Draws Figure 1 FIG. 1 is a partial cross-sectional diagram of a through-hole fuse structure 120 .

[0006] like Figure 1 , 2 As shown, the storage unit includes a MOS tube 110 and a through-hole fuse structure 120. The MOS tube 110 includes a drain 111, a source 112 (N+), a body terminal P+, and a gate 113, wherein the source 112 constitutes a cathode terminal; the through-hole fuse structure 120 includes a polysilicon layer 121, a contact hole 122, a first aluminum layer 123, a through-hole 124, a second aluminum layer 125, and an oxide layer 126, wherein there are three contact holes 123 and one through-hole 124, all of which are provided with fuses, and the through-hole 124 is led out through the second aluminum layer 125 to constitute an anode terminal, and one end of the polysilicon layer 121 is connected to the drain 111, and the other end is connected to the through-hole 124, that is, connected to the anode.

[0007] For Figure 2The through-hole fuse structure 120 shown in the figure has only one through-hole 124, so its current capacity is the weakest and is destroyed first. Therefore, during the programming process, the through-hole 124 is destroyed and blown open by the current. The destroyed through-hole 124 may re-adhere under long-term high temperature due to the existence of the surrounding oxide layer, thereby affecting reliability.

[0008] Therefore, providing a fuse structure, a storage unit, and a method for manufacturing the fuse structure to improve reliability is an urgent problem to be solved in the art. Summary of the invention

[0009] In view of this, the present invention provides a fuse structure, a storage unit and a method for manufacturing the fuse structure, which solve the technical problem of reliability of the fuse structure in the prior art.

[0010] In one aspect, the present invention provides a fuse structure, comprising:

[0011] Oxide layer;

[0012] A polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer are sequentially stacked in the oxide layer, wherein the first through hole is configured as a fuse through hole and is disposed between the first metal layer and the second metal layer;

[0013] A groove is configured in the oxide layer and is set around the first metal layer, the first through hole, and the second metal layer. The groove includes a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer.

[0014] Optionally, the second inner wall is flush with an end of the first metal layer.

[0015] Optionally, the material of the first metal layer and the second metal layer is aluminum.

[0016] Optionally, the first contact hole is configured as a fuse contact hole.

[0017] In another aspect, the present invention provides a storage unit, comprising:

[0018] The fuse structure described in any one of the above items;

[0019] a programming transistor;

[0020] an anode terminal, disposed on the second metal layer;

[0021] a cathode terminal, disposed on the programming transistor;

[0022] When the programming transistor is turned on, the anode terminal is electrically connected to the cathode terminal.

[0023] Optionally, the programming transistor includes a drain, a source, and a gate, wherein the drain is electrically connected to the polysilicon layer in the fuse structure, and the source is configured as the cathode terminal.

[0024] Optionally, the anode terminal and the cathode terminal are configured as a first bias voltage, and when the programming transistor is turned on, the first through hole is burned.

[0025] Optionally, the programming transistor is an NMOS transistor or a PMOS transistor.

[0026] In another aspect, the present invention provides a method for manufacturing a fuse structure, comprising:

[0027] Forming a polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer stacked in sequence, wherein the first through hole is configured as a fuse through hole and is disposed between the first metal layer and the second metal layer;

[0028] Filling an oxide layer on the polysilicon layer, the plurality of first contact holes, the first metal layer, the first through hole, and the second metal layer;

[0029] A groove is formed in the oxide layer, and the groove is arranged around the first metal layer, the first through hole, and the second metal layer. The groove includes a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer.

[0030] Optionally, forming the groove in the oxide layer comprises:

[0031] forming a passivation layer on the oxide layer;

[0032] forming an opening in the passivation layer;

[0033] The oxide layer is etched through the opening to form the recess.

[0034] A fuse structure, a storage unit and a method for manufacturing the fuse structure of the present invention have grooves in the oxide layer of the fuse structure. When the first through hole is destroyed and exploded by a large current, the melted metal will flow into the groove. At this time, since the melted metal will flow into the groove, the melted metal will not re-adhere even after a long period of high temperature, thereby improving the reliability of the fuse structure, that is, improving the reliability of the fuse structure, and further improving the reliability of the storage unit.

[0035] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0037] Figure 1 is a schematic diagram of the structure of a conventional storage unit;

[0038] Figure 2 Draws Figure 1 A partial cross-sectional diagram of a through-hole fuse structure 120 in FIG.

[0039] Figure 3 A schematic structural diagram of a fuse structure according to an embodiment of the present invention;

[0040] Figure 4 A schematic structural diagram of a storage unit according to another embodiment of the present invention;

[0041] Figure 5 The figure is a flow chart of a method for manufacturing a fuse structure according to another embodiment of the present invention. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0043] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0044] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0045] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0046] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0047] refer to Figure 3 , Figure 3 FIG. 4 is a schematic diagram of a fuse structure according to an embodiment of the present invention.

[0048] like Figure 3 As shown, the fuse structure 220 includes an oxide layer 226 , a polysilicon layer 221 , a plurality of first contact holes 222 , a first metal layer 223 , a first through hole 224 , a second metal layer 225 and a groove 227 .

[0049] In this embodiment, the polysilicon layer 221, multiple first contact holes 222, the first metal layer 223, the first through hole 224, and the second metal layer 225 are stacked in sequence in the oxide layer 226, that is, from bottom to top, they are the polysilicon layer 221, multiple first contact holes 222, the first metal layer 223, the first through hole 224, and the second metal layer 225, wherein the first through hole 224 is configured as a fuse through hole, that is, a fuse is provided in the through hole 224, which is arranged between the first metal layer 223 and the second metal layer 225.

[0050] In this embodiment, the groove 227 is configured in the oxide layer 226 and is set around the first metal layer 223, the first through hole 224, and the second metal layer 225. The groove 227 includes a first inner wall 227a, a second inner wall 227b, and a bottom wall 227c located between the first inner wall 227a and the second inner wall 227b, wherein the first inner wall 227a is far away from the first metal layer 223, and the second inner wall 227b is close to the first metal layer 223. The bottom wall 227c of the groove 227 is lower than the bottom of the first metal layer 223, that is, a lower groove is formed next to the first metal layer 223.

[0051] In this embodiment, since a groove 227 is provided in the oxide layer 226 and surrounds the first metal layer 223, the first through hole 224, and the second metal layer 225, and the bottom wall 227c of the groove 227 is lower than the bottom of the first metal layer 223, when the first through hole 224 is destroyed and exploded by a large current, the melted metal will flow into the groove 227. At this time, since the melted metal will flow into the groove 227, even after a long period of high temperature, the melted metal will not re-adhere, thereby improving the reliability of the fuse structure 220, that is, the reliability of the fuse structure 220 can be improved.

[0052] In this embodiment, the second inner wall 227 b may be flush with the end of the first metal layer 223 . Here, flush may mean approximately flush. However, in other embodiments, the second inner wall 227 b may also be close to the outside or inside of the first metal layer 223 .

[0053] In this embodiment, the material of the first metal layer 223 and the second metal layer 225 is aluminum, that is, the first metal layer 223 and the second metal layer 225 can be aluminum layers.

[0054] In this embodiment, the first contact hole 222 may also be configured as a fuse contact hole, that is, a fuse may also be configured in the first contact hole 222 .

[0055] refer to Figure 4 , Figure 4 The figure is a schematic structural diagram of a storage unit according to another embodiment of the present invention.

[0056] like Figure 4 As shown in FIG. 2 , the memory cell includes a fuse structure 220 , a programming transistor 210 , an anode terminal, and a cathode terminal.

[0057] In this embodiment, the fuse structure 220 may be as follows: Figure 3 The structure shown includes an oxide layer 226, a polysilicon layer 221, a plurality of first contact holes 222, a first metal layer 223, a first through hole 224, a second metal layer 225 and a groove 227. The specific structure is not repeated here. The anode terminal is configured on the second metal layer 225, and the cathode terminal is configured on the programming transistor 110. For the programming transistor 110, it can include a drain 211, a source 212, a gate 213 and a body terminal P+, wherein the drain 211 is electrically connected to the polysilicon layer 221 in the fuse structure 220, and the source 212 serves as a cathode. Figure 4 As shown, the memory cell may further include a P-well 230 and a P-type substrate 240. Of course, the memory cell may further include other structures, which will not be described in detail here.

[0058] In this embodiment, when the programming transistor 110 is turned on, that is, the gate 213 inputs a control signal, such as a high level, at this time, the anode terminal and the cathode terminal are electrically connected.

[0059] In this embodiment, the anode terminal and the cathode terminal can be configured as a first bias voltage, and when the programming transistor 210 is turned on, the first through hole 224 is burned. Here, the first bias voltage is a high bias voltage to achieve a programming operation.

[0060] In this embodiment, since the anode terminal and the cathode terminal are configured as a high bias voltage, at this time, the first through hole 224 will be burned by a large current, such as exploded, and the melted metal will flow downward into the groove 227. However, since the present embodiment is provided with a groove 227, when the first through hole 224 is destroyed and exploded by the large current, the melted metal will flow into the groove 227, and, since the bottom wall 227c of the groove 227 is lower than the bottom of the first metal layer 223, that is, and the bottom wall 227c of the groove 227 is relatively low relative to the first metal layer 223, the melted metal can flow directly onto the bottom wall 227c of the groove 227. When these melted metals flow into the groove 227, even after a long period of high temperature, these melted metals will not re-adhere, thereby improving the reliability of the fuse structure 220, that is, the reliability of the through-hole fuse structure 220 can be improved, thereby improving the reliability of the storage unit.

[0061] like Figure 4 As shown, the programming transistor 210 is an NMOS transistor, but in other embodiments, the programming transistor 210 can also be a PMOS transistor, electrically connected to the fuse structure 220, and provided with a cathode terminal. For the sake of simplicity, it is not repeated here. Of course, the programming transistor 220 can also be other structures, electrically connected to the fuse structure 220, and provided with a cathode terminal. In short, the focus of this embodiment is on the improvement of the fuse structure 220. There can be many types of programming transistors 210, which are not listed here one by one.

[0062] refer to Figure 5 , Figure 5 The figure is a flow chart of a method for manufacturing a fuse structure according to another embodiment of the present invention.

[0063] The following will be combined Figure 5 and Figure 3 The manufacturing method of the fuse structure in this embodiment is specifically described.

[0064] Step S510: forming a polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer stacked in sequence, wherein the first through hole is configured as a fuse through hole and is disposed between the first metal layer and the second metal layer.

[0065] Specifically, Figure 3As shown, the polysilicon layer 221, multiple first contact holes 222, the first metal layer 223, the first through hole 224, and the second metal layer 225 are stacked in sequence, that is, from bottom to top, they are the polysilicon layer 221, multiple first contact holes 222, the first metal layer 223, the first through hole 224, and the second metal layer 225, wherein the first through hole 224 is configured as a fuse through hole, that is, a fuse is provided in the through hole 224, which is arranged between the first metal layer 223 and the second metal layer 225.

[0066] Step S520: filling an oxide layer on the polysilicon layer, the plurality of first contact holes, the first metal layer, the first through hole, and the second metal layer.

[0067] Specifically, the oxide layer 226 is filled on the polysilicon layer 221 , the plurality of first contact holes 222 , the first metal layer 223 , the first through hole 224 , and the second metal layer 225 .

[0068] Step S530: A groove is formed in the oxide layer, and the groove is arranged around the first metal layer, the first through hole, and the second metal layer. The groove includes a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer.

[0069] Specifically, Figure 3 As shown, a groove 227 is formed in the oxide layer 226, that is, the groove 227 is configured in the oxide layer 226 and is arranged around the first metal layer 223, the first through hole 224, and the second metal layer 225. The groove 227 includes a first inner wall 227a, a second inner wall 227b and a bottom wall 227c located between the first inner wall 227a and the second inner wall 227b, wherein the first inner wall 227a is far away from the first metal layer 223, and the second inner wall 227b is close to the first metal layer 223. The bottom wall 227c of the groove 227 is lower than the bottom of the first metal layer 223, that is, a lower groove is formed next to the first metal layer 223.

[0070] In this embodiment, forming the groove in the oxide layer 226 may include: forming a passivation layer (not shown) on the oxide layer 226; forming an opening on the passivation layer; etching the oxide layer 226 through the opening to form the groove 227. In this embodiment, a passivation layer commonly used in semiconductor processes may be used, without the need for an additional layer, and an opening is opened to etch the oxide layer 226 to form the groove 227, thereby not increasing the cost.

[0071] In this embodiment, since a groove 227 is provided in the oxide layer 226 and surrounds the first metal layer 223, the first through hole 224, and the second metal layer 225, and the bottom wall 227c of the groove 227 is lower than the bottom of the first metal layer 223, when the first through hole 224 is destroyed and exploded by the current, the melted metal will flow into the groove 227. At this time, since the melted metal will flow into the groove 227, even after a long period of high temperature, the melted metal will not re-adhere, thereby improving the reliability of the fuse structure 220, that is, the reliability of the fuse structure 220 can be improved.

[0072] In the above-mentioned embodiment of the present invention, a fuse structure, a storage unit and a method for manufacturing a fuse structure are provided with a groove in the oxide layer of the fuse structure. When the first through hole is destroyed and exploded by a large current, the melted metal will flow into the groove. At this time, since the melted metal will flow into the groove, even after a long period of high temperature, the melted metal will not re-adhere, thereby improving the reliability of the fuse structure, that is, the reliability of the fuse structure can be improved, and then the reliability of the storage unit can be improved.

[0073] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention.

Claims

1. A fuse structure, characterized in that: include: Oxide layer; A polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer are sequentially stacked in the oxide layer, wherein the first through hole is configured as a fuse through hole and is disposed between the first metal layer and the second metal layer; A groove is configured in the oxide layer and is set around the first metal layer, the first through hole, and the second metal layer. The groove includes a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer.

2. The fuse structure according to claim 1, characterized in that: The second inner wall is flush with an end of the first metal layer.

3. The fuse structure according to claim 1, characterized in that: The materials of the first metal layer and the second metal layer are aluminum.

4. The fuse structure according to claim 1, characterized in that: The first contact hole is configured as a fuse contact hole.

5. A storage unit, characterized in that: include: The fuse structure according to any one of claims 1 to 4; a programming transistor; an anode terminal, disposed on the second metal layer; a cathode terminal, disposed on the programming transistor; When the programming transistor is turned on, the anode terminal is electrically connected to the cathode terminal.

6. The storage unit according to claim 5, characterized in that The programming transistor includes a drain, a source, and a gate, wherein the drain is electrically connected to the polysilicon layer in the fuse structure, and the source is configured as the cathode terminal.

7. The storage unit according to claim 5, characterized in that The anode terminal and the cathode terminal are configured as a first bias voltage, and when the programming transistor is turned on, the first through hole is burned.

8. The storage unit according to claim 5, characterized in that The programming transistor is an NMOS transistor or a PMOS transistor.

9. A method for manufacturing a fuse structure, characterized in that: include: Forming a polysilicon layer, a plurality of first contact holes, a first metal layer, a first through hole, and a second metal layer stacked in sequence, wherein the first through hole is configured as a fuse through hole and is disposed between the first metal layer and the second metal layer; Filling an oxide layer on the polysilicon layer, the plurality of first contact holes, the first metal layer, the first through hole, and the second metal layer; A groove is formed in the oxide layer, and the groove is arranged around the first metal layer, the first through hole, and the second metal layer. The groove includes a first inner wall, a second inner wall, and a bottom wall located between the first inner wall and the second inner wall, wherein the second inner wall is close to the first metal layer, and the bottom wall of the groove is lower than the bottom of the first metal layer.

10. The method for manufacturing a fuse structure according to claim 9, characterized in that: Forming the groove in the oxide layer includes: forming a passivation layer on the oxide layer; forming an opening in the passivation layer; The oxide layer is etched through the opening to form the recess.

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