Method for bonding wafers and resulting semiconductor element

Abstract

The invention relates to a method for bonding wafers and an obtained semiconductor element, and the method comprises the following steps: S1, forming a first water absorption layer on the surface of a first wafer, and forming a second water absorption layer on the surface of a second wafer; s2, forming a first insulating layer on the surface of the first water absorption layer, and forming a second insulating layer on the surface of the second water absorption layer; s3, the first insulating layer and the second insulating layer are jointed; the first water absorption layer and the second water absorption layer contain water absorption materials. According to the bonding method, holes can be prevented from being formed in the insulating layer, and the device performance can be further improved.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing, and specifically, to a method for bonding wafers and the resulting semiconductor components. Background Art

[0002] In modern times, microelectronics technology has also become the foundation of the entire information industry and an important symbol reflecting a country's comprehensive strength and economic development level. With the development of integrated circuit technology, chips with high speed, high device density, low power consumption, and low cost have increasingly become the main products of very large scale integrated circuit manufacturing.

[0003] The bonding of semiconductor components is to stack two wafers together. During the bonding process, a Void effect is formed in the insulating layer, that is, holes are generated, which affects the performance of the device. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a method for bonding wafers and the resulting semiconductor components.

[0005] To achieve the above purpose, the first aspect of the present disclosure provides a method for bonding wafers, the method including the following steps:

[0006] S1. Form a first water-absorbing layer on the surface of the first wafer and a second water-absorbing layer on the surface of the second wafer;

[0007] S2. Form a first insulating layer on the surface of the first water-absorbing layer and a second insulating layer on the surface of the second water-absorbing layer;

[0008] S3. Bond the first insulating layer and the second insulating layer;

[0009] The first water-absorbing layer and the second water-absorbing layer contain water-absorbing materials.

[0010] Optionally, under the conditions of 25°C and 101.325 kPa, the water-absorbing material is placed in the air for 12 hours. Compared with the water-absorbing material before placement, the stress of the water-absorbing material after placement increases by 500 MPa or less.

[0011] Optionally, the water-absorbing material includes nitrogen-doped silicon carbide or silicon nitride.

[0012] Optionally, in step S1, the method for forming the first water-absorbing layer and the second water-absorbing layer includes chemical vapor deposition;

[0013] The conditions include: the temperature is 350 - 400°C, the reaction pressure is 10 Torr or less, the high-frequency radio frequency power is less than 2500 W, and the low-frequency radio frequency power is less than 1500 W;

[0014] The raw materials include ammonia gas and a silicon source, and the silicon source includes silane or tetramethylsilane.

[0015] Optionally, the raw materials include ammonia gas and silane. The flow rate of the ammonia gas is 500 - 2500 sccm, and the flow rate of the silane is less than 2000 sccm; or,

[0016] The raw materials include ammonia gas and tetramethylsilane. The flow rate of the ammonia gas is 1000 - 20000 sccm, and the flow rate of the tetramethylsilane is less than 2000 sccm.

[0017] Optionally, in step S1, the thicknesses of the first water-absorbing layer and the second water-absorbing layer are respectively

[0018] Optionally, in step S2, the first insulating layer and the second insulating layer contain silicon oxide compounds.

[0019] Optionally, in step S2, the method for forming the first insulating layer and the second insulating layer includes chemical vapor deposition;

[0020] The conditions include: the temperature is 350 - 400 °C, the reaction pressure is below 10 Torr, the high-frequency radio frequency power is less than 2500 W, and the low-frequency radio frequency power is less than 1500 W;

[0021] The raw materials include tetraethyl orthosilicate and oxygen. The flow rate of the tetraethyl orthosilicate is 1000 - 40000 sccm, and the flow rate of the oxygen is 500 - 10000 sccm.

[0022] The second aspect of the present disclosure provides a semiconductor element prepared by using the method described in the first aspect of the present disclosure.

[0023] The third aspect of the present disclosure provides a semiconductor element, which includes a first wafer and a second wafer;

[0024] A first water-absorbing layer, a first insulating layer, a second insulating layer, and a second water-absorbing layer are sequentially stacked between the first wafer and the second wafer;

[0025] The first water-absorbing layer and the second water-absorbing layer include water-absorbing materials.

[0026] Through the above technical solutions, a water-absorbing layer is formed between the wafer and the insulating layer in the present disclosure, forming a sandwich structure of wafer - water-absorbing layer - insulating layer. The water-absorbing layer includes a water-absorbing material, adsorbing the H 2 O generated during the bonding process, avoiding the formation of holes in the insulating layer, and further improving the device performance.

[0027] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are provided to further understand the present disclosure, and form a part of the specification. Together with the following detailed description, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0029] Figure 1 is a flowchart of a specific embodiment of the method for bonding wafers of the present disclosure.

[0030] Figure 2 is a schematic structural diagram of a semiconductor element obtained by bonding the method of the present disclosure.

[0031] DESCRIPTION OF REFERENCE NUMERALS

[0032] 1 First wafer

[0033] 2 First water absorption layer

[0034] 3 First insulating layer

[0035] 4 Second insulating layer

[0036] 5 Second water absorption layer

[0037] 6 Second wafer DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following describes in detail the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and understanding the present disclosure, and are not used to limit the present disclosure.

[0039] As Figure 1 shown, the first aspect of the present disclosure provides a method for bonding wafers, which includes the following steps:

[0040] S1. Form a first water absorption layer on the surface of the first wafer and a second water absorption layer on the surface of the second wafer;

[0041] S2. Form a first insulating layer on the surface of the first water absorption layer and a second insulating layer on the surface of the second water absorption layer;

[0042] S3. Bond the first insulating layer and the second insulating layer;

[0043] The first water absorption layer and the second water absorption layer contain water-absorbing materials.

[0044] During the bonding process of the wafers, H 2 O outgassing will occur, H 2O forms a Void effect in the insulating layer, that is, holes are generated, which in turn affects the performance of the device. The inventors of the present disclosure form a water-absorbing layer between the wafer and the insulating layer to form a sandwich structure of wafer - water-absorbing layer - insulating layer, and absorb the H generated during the bonding process through the hygroscopicity of the water-absorbing material 2 O to avoid the formation of holes in the insulating layer and further improve the device performance.

[0045] In the present disclosure, the water-absorbing layer can be formed on the back side of the wafer or on the front side of the wafer, which is specifically set according to actual production requirements. The definitions of the back side and the front side of the wafer are conventional in the art and will not be elaborated here.

[0046] In the present disclosure, in step S3, after the first insulating layer and the second insulating layer are bonded, the first insulating layer and the second insulating layer are adhered.

[0047] In the present disclosure, the first wafer and the second wafer can be the same or different.

[0048] In the present disclosure, the first wafer and the second wafer can be obtained after the metal wire wiring is completed.

[0049] In order to obtain a better moisture absorption effect, according to an embodiment of the present disclosure, the water-absorbing material is placed in the air for 12 hours under the conditions of 25 °C and 101.325 kPa. Compared with the water-absorbing material before placement, the stress of the water-absorbing material after placement increases by 500 MPa or less. For example, it can increase by 500 MPa, 450 MPa, 400 MPa, 300 MPa, 200 MPa, 150 MPa, etc.; the stress refers to the internal stress of the water-absorbing material, and the specific method for stress testing can be: optical measurement, specifically, an ellipsometer can be used.

[0050] According to a specific embodiment of the present disclosure, the water-absorbing material can include nitrogen-doped silicon carbide or silicon nitride; among them, under the conditions of 25 °C and 101.325 kPa, after being placed in the air for 12 hours, the stress of the nitrogen-doped silicon carbide increases by 500 MPa; the components of the first water-absorbing layer and the second water-absorbing layer can be the same or different.

[0051] According to an embodiment of the present disclosure, in step S1, the method for forming the first water-absorbing layer and the second water-absorbing layer includes chemical vapor deposition, and the conditions include: the temperature is 350-400 °C, for example, it can be 350 °C, 370 °C, 300 °C, etc., the reaction pressure is below 10 Torr, for example, it can be 1 Torr, 2 Torr, 5 Torr, 7 Torr, 10 Torr, etc., the pressure is usually not 0, the high-frequency radio frequency power is less than 2500 W and not 0, for example, it can be 500 W, 1000 W, 1200 W, 1500 W, 1800 W, 2000 W, 2300 W, etc., the low-frequency radio frequency power is less than 1500 W and not 0, for example, it can be 500 W, 1000 W, 1200 W, etc., and other conditions for forming the first water-absorbing layer and the second water-absorbing layer are conventional in the art; the conditions for forming the first water-absorbing layer and the second water-absorbing layer can be the same or different.

[0052] According to an embodiment of the present disclosure, the raw materials used in chemical vapor deposition include ammonia and a silicon source, and the silicon source includes silane or tetramethylsilane.

[0053] According to a specific embodiment of the present disclosure, the raw materials include ammonia and silane, the flow rate of ammonia is 500-2500 sccm, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 1700 sccm, 2000 sccm, 2500 sccm, etc., and the flow rate of silane is less than 2000 sccm and not 0, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 1700 sccm, etc.

[0054] According to a specific embodiment of the present disclosure, the raw materials include ammonia and tetramethylsilane, the flow rate of ammonia is 1000-20000 sccm, for example, it can be 1000 sccm, 1500 sccm, 1700 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 5000 sccm, 10000 sccm, 13000 sccm, 18000 sccm, 20000 sccm, etc., and the flow rate of tetramethylsilane is less than 2000 sccm and not 0, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 1700 sccm, etc.

[0055] In order to obtain a better moisture absorption effect, according to an embodiment of the present disclosure, in step S1, the thicknesses of the first water-absorbing layer and the second water-absorbing layer are respectively The thicknesses of the first water-absorbing layer and the second water-absorbing layer can be the same or different, and the thicknesses of the first water-absorbing layer and the second water-absorbing layer are controlled by the deposition time.

[0056] According to an embodiment of the present disclosure, in step S2, the first insulating layer and the second insulating layer contain silicon oxide compounds. Specifically, both the first insulating layer and the second insulating layer are composed of silicon oxide compounds, for example, composed of silicon dioxide.

[0057] According to an embodiment of the present disclosure, in step S2, the method for forming the first insulating layer and the second insulating layer includes chemical vapor deposition. The conditions include: the temperature is 350 - 400 °C, for example, it can be 350 °C, 370 °C, 300 °C, etc.; the reaction pressure is below 10 Torr, for example, it can be 1 Torr, 2 Torr, 5 Torr, 7 Torr, 10 Torr, etc. The pressure is usually not 0. The high-frequency radio frequency power is less than 2500 W and not 0, for example, it can be 500 W, 1000 W, 1200 W, 1500 W, 1800 W, 2000 W, etc. The low-frequency radio frequency power is less than 1500 W and not 0, for example, it can be 500 W, 1000 W, 1200 W, etc. The raw materials include tetraethyl orthosilicate and oxygen. The flow rate of tetraethyl orthosilicate is 1000 - 40000 sccm, for example, it can be 1000 sccm, 1500 sccm, 1700 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 5000 sccm, 10000 sccm, 13000 sccm, 18000 sccm, 20000 sccm, 30000 sccm, 40000 sccm, etc. The flow rate of oxygen is 500 - 10000 sccm, for example, it can be 500 sccm, 800 sccm, 1000 sccm, 1500 sccm, 1700 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, 9000 sccm, 10000 sccm, etc. Other conditions for forming the first insulating layer and the second insulating layer are conventional in the art; the thicknesses of the first insulating layer and the second insulating layer are set according to the requirements of subsequent processes, and the present disclosure does not make specific limitations. The thicknesses of the first insulating layer and the second insulating layer can be controlled by the deposition time.

[0058] In the present disclosure, in step S3, the method and conditions for bonding the first insulating layer and the second insulating layer are conventional in the art, and the present disclosure does not make specific limitations.

[0059] According to a specific embodiment of the present disclosure, the method for bonding wafers may include the following steps:

[0060] S1. Adopt chemical vapor deposition (CVD) to form a first water-absorbing layer on the surface of the first wafer and a second water-absorbing layer on the surface of the second wafer;

[0061] The thicknesses of the first water-absorbing layer and the second water-absorbing layer are respectively

[0062] The conditions include: the temperature is 350 - 400 °C, the reaction pressure is below 10 Torr, the high-frequency RF power is less than 2500 W and not zero, and the low-frequency RF power is less than 1500 W and not zero;

[0063] The first water-absorbing layer and the second water-absorbing layer include a water-absorbing material. Under the conditions of 25 °C and 101.325 kPa, the water-absorbing material is placed in air for 12 hours. Compared with the water-absorbing material before placement, the stress of the water-absorbing material after placement increases by 500 MPa or less; The water-absorbing material may specifically include nitrogen-doped silicon carbide or silicon nitride;

[0064] When the water-absorbing layer is composed of silicon nitride, the raw materials used for chemical vapor deposition include ammonia gas and silane. The flow rate of the ammonia gas is 500 - 2500 sccm, and the flow rate of the silane is less than 2000 sccm and not zero;

[0065] When the water-absorbing layer is composed of nitrogen-doped silicon carbide (NDC), the raw materials used for chemical vapor deposition include ammonia gas and tetramethylsilane. The flow rate of the ammonia gas is 1000 - 20000 sccm, and the flow rate of the tetramethylsilane is less than 2000 sccm and not zero;

[0066] S2. Adopt the method of chemical vapor deposition (CVD) to form a first insulating layer on the surface of the first water-absorbing layer and a second insulating layer on the surface of the second water-absorbing layer;

[0067] The conditions include: the temperature is 350 - 400 °C, the reaction pressure is below 10 Torr, the high-frequency RF power is less than 1500 W and not zero, and the low-frequency RF power is less than 1500 W and not zero;

[0068] The raw materials include tetraethyl orthosilicate and oxygen. The flow rate of the tetraethyl orthosilicate is 1000 - 40000 sccm, and the flow rate of the oxygen is 500 - 10000 sccm;

[0069] The formed first insulating layer and second insulating layer are both composed of silicon oxide compounds;

[0070] S3. Bond the first insulating layer and the second insulating layer together.

[0071] Adopt the above specific implementation manner to form a water-absorbing layer between the wafer and the insulating layer. The H 2 O generated during the bonding process can be adsorbed by the water-absorbing layer, avoiding the formation of voids in the insulating layer and further improving the device performance.

[0072] The second aspect of the present disclosure provides a semiconductor element prepared by using the method described in the first aspect of the present disclosure.

[0073] As Figure 2 shown, a third aspect of the present disclosure provides a semiconductor component, which includes a first wafer and a second wafer;

[0074] A first water-absorbing layer, a first insulating layer, a second insulating layer, and a second water-absorbing layer are sequentially stacked between the first wafer and the second wafer;

[0075] The first water-absorbing layer and the second water-absorbing layer include water-absorbing materials.

[0076] The semiconductor component provided by the third aspect of the present disclosure has the same features as the semiconductor component provided by the second aspect of the present disclosure, and will not be elaborated herein.

[0077] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0078] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0079] Furthermore, any combination can be made between various different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. Method for bonding wafers, characterized in that, the method comprises the following steps: S1. Form a first water-absorbing layer on the surface of the first wafer and a second water-absorbing layer on the surface of the second wafer; S2. Form a first insulating layer on the surface of the first water-absorbing layer and a second insulating layer on the surface of the second water-absorbing layer; S3. Bond the first insulating layer and the second insulating layer; the first water-absorbing layer and the second water-absorbing layer contain water-absorbing materials.

2. The method according to claim 1, wherein, under the conditions of 25 °C and 101.325 kPa, the water-absorbing material is placed in air for 12 hours, and the stress of the water-absorbing material after placement increases by 500 MPa or less compared with the water-absorbing material before placement.

3. The method according to claim 2, wherein, the water-absorbing material comprises nitrogen-doped silicon carbide or silicon nitride.

4. The method according to claim 3, wherein, in step S1, the method for forming the first water-absorbing layer and the second water-absorbing layer includes chemical vapor deposition; the conditions include: the temperature is 350 - 400 °C, the reaction pressure is 10 Torr or less, the high-frequency radio frequency power is less than 2500 W, and the low-frequency radio frequency power is less than 1500 W; the raw materials include ammonia gas and a silicon source, and the silicon source includes silane or tetramethylsilane.

5. The method according to claim 4, wherein, the raw materials include ammonia gas and silane, the flow rate of the ammonia gas is 500 - 2500 sccm, and the flow rate of the silane is less than 2000 sccm; or, the raw materials include ammonia gas and tetramethylsilane, the flow rate of the ammonia gas is 1000 - 20000 sccm, and the flow rate of the tetramethylsilane is less than 2000 sccm.

6. The method according to claim 1, wherein, In step S1, the thicknesses of the first water-absorbing layer and the second water-absorbing layer are respectively 7. The method according to claim 1, wherein, in step S2, the first insulating layer and the second insulating layer contain silicon oxide compounds.

8. The method according to claim 7, wherein, in step S2, the method for forming the first insulating layer and the second insulating layer includes chemical vapor deposition; the conditions include: the temperature is 350 - 400 °C, the reaction pressure is 10 Torr or less, the high-frequency radio frequency power is less than 2500 W, and the low-frequency radio frequency power is less than 1500 W; the raw materials include tetraethyl orthosilicate and oxygen, the flow rate of the tetraethyl orthosilicate is 1000 - 40000 sccm, and the flow rate of the oxygen is 500 - 10000 sccm.

9. A semiconductor device prepared by using the method according to any one of claims 1 - 8.

10. A semiconductor device, characterized in that, the semiconductor device comprises a first wafer and a second wafer; a first water-absorbing layer, a first insulating layer, a second insulating layer and a second water-absorbing layer are sequentially stacked between the first wafer and the second wafer; the first water-absorbing layer and the second water-absorbing layer comprise water-absorbing materials.

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