MIM capacitor manufacturing method

Abstract

The invention discloses a manufacturing method of an MIM capacitor. The manufacturing method comprises the following steps of S1, forming a lower layer metal electric plate with an M1 pattern on the lower layer metal electric plate; s2, depositing a silicon nitride dielectric layer on the lower metal electric plate with the M1 pattern; s3, photoetching an NM pattern on the silicon nitride dielectric layer; s4, performing sputtering coating on the silicon nitride dielectric layer in the NM pattern to form an upper-layer metal electric plate; s5, performing lift photoresist removal on the upper metal electric plate; s6, depositing a silicon nitride protection layer on the silicon nitride dielectric layer and the upper metal electroplate; s7, using a PV photomask to open holes in the silicon nitride protection layer to the upper metal electroplate; s8, a polymer layer is manufactured in a spin coating mode; s9, opening holes in the polymer layer to the upper metal electroplate by using a PV photomask; and S10, photoetching an M2 pattern by using a metal M2 photomask to obtain a metal connection layer M2. According to the invention, the product yield is stable and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing process and relates to a MIM capacitor manufacturing method. Background Art

[0002] MIM capacitors are used as a passive component in devices in addition to inductors and resistors. MIM capacitors rely on two metal plates and a dielectric layer in the middle to form the main structure. Part of the other two metal plates also serve as metal connection layers. A low dielectric constant polymer layer (POLYIMIDE) is required between the layers to reduce the interlayer capacitance at high frequencies.

[0003] The prior art in making MIM capacitors includes the following steps: making a lower electrode, depositing a silicon nitride dielectric layer, opening holes in the dielectric layer, making a polymer layer, opening holes in the polymer layer, and making an upper electrode. However, when the prior art makes an upper electrode on the surface of a thin capacitor dielectric layer (silicon nitride), during the step of opening holes in the polymer (POLYIMIDE), the breakdown voltage and reliability are easily reduced when etching the surface of the dielectric layer. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing a MIM capacitor, which avoids the problem of reduced breakdown voltage and reliability caused by the step of opening holes in the polymer.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a MIM capacitor manufacturing method, which comprises the following steps:

[0008] S1: forming a lower metal plate with an M1 pattern on the lower metal plate;

[0009] S2: depositing a silicon nitride dielectric layer on the lower metal plate with the M1 pattern;

[0010] S3: Photolithography of NM pattern on the silicon nitride dielectric layer;

[0011] S4: sputtering on the silicon nitride dielectric layer inside the NM pattern to form an upper metal plate;

[0012] S5: liftoff the upper metal plate to remove glue;

[0013] S6: depositing a silicon nitride protective layer on the silicon nitride dielectric layer and the upper metal plate;

[0014] S7: using a PV mask, opening a hole in the silicon nitride protective layer to the upper metal plate;

[0015] S8: forming a polymer layer by spin coating;

[0016] S9: using a PV mask, opening holes in the polymer layer to the upper metal plate;

[0017] S10: using a metal M2 mask to photolithograph an M2 pattern to obtain a metal connection layer M2.

[0018] In step S1, a lower metal plate with an M1 pattern is obtained by using metal M1 mask lithography, metal evaporation and liftoff inversion.

[0019] In step S3, the photoresist used for photolithography of the upper metal plate is lift-off negative photoresist, image-reverse positive photoresist or LOR plus positive photoresist.

[0020] In step S3, the NM graphic is NITRIDE METAL, which means metal nitride.

[0021] In step S4, the material of the upper metal electrode is one of Ti, TiN, TaN, or a combination of one of them and Au.

[0022] The process of forming the upper metal plate in steps S3 to S5 is as follows: first, photolithography is performed to form an opening pattern with an inverted trapezoidal shape, then metal evaporation is performed to allow the metal to enter the inverted trapezoidal opening pattern, and then a liftoff process is performed to remove the glue. Finally, the metal on the glue falls off along with the glue, and the metal in the inverted trapezoidal opening remains to form the upper metal plate.

[0023] In step S7, the opening area of ​​the silicon nitride protection layer is smaller than the area of ​​the upper metal electrode.

[0024] In step S10, a liftoff inversion method is adopted after metal evaporation to obtain a metal connection layer M2.

[0025] In step S10 , the area where the metal connection layer M2 contacts the silicon nitride protection layer is larger than the opening area of ​​the silicon nitride protection layer.

[0026] (III) Beneficial effects

[0027] The MIM capacitor manufacturing method provided by the above technical solution ensures stable and reliable product yield and has the following beneficial effects:

[0028] (1) This method makes a new upper metal plate on the surface of the capacitor dielectric layer (silicon nitride) before opening a hole in the capacitor dielectric layer (silicon nitride). When the new upper metal plate (Ti or TiN or TaN) is used to open a hole in the polymer layer, it blocks the damage caused by the original direct etching of the capacitor dielectric layer (silicon nitride) surface, thereby avoiding a decrease in the capacitor breakdown voltage and reliability. At the same time, it replaces the upper metal plate made after the polymer layer is opened, and the original upper plate becomes the metal connection layer of the new upper plate.

[0029] (2) Using a single PV mask for double exposure saves the mask used for photolithography of opening holes in the silicon nitride protective layer of the upper metal plate (Ti or TiN or TaN).

[0030] (3) Add a silicon nitride protective layer deposition to the upper metal plate (Ti or TiN or TaN) to prevent the upper metal plate from being oxidized during the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the method of the present invention;

[0032] Figure 2 Schematic diagram of the lower metal plate M1 with patterns of the present invention;

[0033] Figure 3 This is a schematic diagram of the result of step S2;

[0034] Figure 4 It is a schematic diagram of the results of step S3 and step S4;

[0035] Figure 5 This is a schematic diagram of the result of step S6;

[0036] Figure 6 This is a schematic diagram of the result of step S7;

[0037] Figure 7 This is a schematic diagram of the result of step S8;

[0038] Figure 8 This is a schematic diagram of the result of step S9;

[0039] Fig. 9 This is a schematic diagram of the result of step S10. DETAILED DESCRIPTION

[0040] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0041] like Figure 1 As shown, the MIM capacitor manufacturing method of this embodiment includes the following steps:

[0042] S1: using metal M1 mask lithography, metal evaporation and liftoff inversion method on the lower metal plate 1 to obtain the lower metal plate 1 with M1 pattern 2;

[0043] The schematic diagram of the lower metal plate 1 with the M1 pattern 2 is as follows: Figure 2 As shown;

[0044] S2: Figure 3 As shown, a silicon nitride dielectric layer 3 is deposited on the lower metal plate 1 with the M1 pattern 2;

[0045] S3: Figure 4 As shown, a NM pattern 5 is photolithographically formed on the silicon nitride dielectric layer 3;

[0046] Wherein, NM is NITRIDE METAL, metal nitride; wherein, the photoresist used in photolithography is lift off negative photoresist or image reverse positive photoresist or LOR plus positive photoresist;

[0047] S4: Figure 4 As shown, an upper metal plate 4 is formed by sputtering on the silicon nitride dielectric layer 3 inside the NM pattern 5. The material of the upper metal plate 4 is one of Ti, TiN, and TaN, or a combination of one of them and Au;

[0048] S5: liftoff the upper metal plate 4 to remove the glue;

[0049] Among them, steps S3 to S5 are specifically as follows: first, photolithography is performed to form an opening pattern with an inverted trapezoidal shape, then metal evaporation is performed to allow metal to enter the inverted trapezoidal opening pattern, and then a liftoff process is performed to remove the glue, and finally the metal on the glue falls off together with the glue, and the metal in the inverted trapezoidal opening remains to form an upper metal plate 4;

[0050] S6: Figure 5 As shown, a silicon nitride protective layer 6 is deposited on the silicon nitride dielectric layer 3 and the upper metal plate 4;

[0051] S7: Figure 6 As shown, a PV mask (PV photolithography 7) is used to open a hole in the silicon nitride protective layer 6 to the upper metal plate 4, wherein the opening area of ​​the silicon nitride protective layer 6 is smaller than the area of ​​the upper metal plate 4;

[0052] S8: Figure 7 As shown, the polymer layer 8 is made by spin coating;

[0053] S9: Figure 8As shown, a PV mask (PV photolithography 7, Polyimide via) is used to open holes in the polymer layer 8 to the upper metal plate 4;

[0054] S10: Fig. 9 As shown, the M2 pattern is photolithographically formed using a metal M2 mask, and a liftoff inversion method is adopted after metal evaporation to obtain a metal connection layer M29, wherein the area of ​​the metal connection layer M29 contacting the silicon nitride protection layer 6 is larger than the opening area of ​​the silicon nitride protection layer 6.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for manufacturing a MIM capacitor, characterized in that: The following steps are involved: S1: forming a lower metal plate with an M1 pattern on the lower metal plate; S2: depositing a silicon nitride dielectric layer on the lower metal plate with the M1 pattern; S3: Photolithography of NM pattern on the silicon nitride dielectric layer; S4: sputtering on the silicon nitride dielectric layer inside the NM pattern to form an upper metal plate; S5: liftoff the upper metal plate to remove glue; S6: depositing a silicon nitride protective layer on the silicon nitride dielectric layer and the upper metal plate; S7: using a PV mask, opening a hole in the silicon nitride protective layer to the upper metal plate; S8: forming a polymer layer by spin coating; S9: using a PV mask, opening holes in the polymer layer to the upper metal plate; S10: using a metal M2 mask to photolithograph an M2 pattern to obtain a metal connection layer M2.

2. The method for manufacturing a MIM capacitor according to claim 1, wherein: In step S1, a lower metal plate with an M1 pattern is obtained by using metal M1 mask lithography, metal evaporation and liftoff inversion.

3. The method for manufacturing a MIM capacitor according to claim 2, wherein: In step S3, the photoresist used for photolithography of the upper metal plate is lift off negative photoresist, image reverse positive photoresist or LOR plus positive photoresist.

4. The method for manufacturing a MIM capacitor according to claim 3, wherein: In step S3, the NM graphic is NITRIDEMETAL, which means metal nitride.

5. The method for manufacturing a MIM capacitor according to claim 4, wherein: In step S4, the material of the upper metal electrode is one of Ti, TiN, TaN, or a combination of one of them and Au.

6. The method for manufacturing a MIM capacitor according to claim 5, wherein: The process of forming the upper metal plate in steps S3 to S5 is as follows: first, photolithography is performed to form an opening pattern with an inverted trapezoidal shape, then metal evaporation is performed to allow the metal to enter the inverted trapezoidal opening pattern, and then a liftoff process is performed to remove the glue. Finally, the metal on the glue falls off along with the glue, and the metal in the inverted trapezoidal opening remains to form the upper metal plate.

7. The method for manufacturing a MIM capacitor according to claim 6, wherein: In step S7, the opening area of ​​the silicon nitride protection layer is smaller than the area of ​​the upper metal electrode.

8. The method for manufacturing a MIM capacitor according to claim 7, wherein: In step S10, a liftoff inversion method is adopted after metal evaporation to obtain a metal connection layer M2.

9. The method for manufacturing a MIM capacitor according to claim 8, wherein: In step S10 , the area where the metal connection layer M2 contacts the silicon nitride protection layer is larger than the opening area of ​​the silicon nitride protection layer.

10. A MIM capacitor prepared by the MIM capacitor manufacturing method according to any one of claims 1 to 9.

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