Wafer curvature adjustment method

Abstract

This disclosure provides a wafer curvature adjustment method, comprising: providing a first wafer; and forming a first material layer having a first fixed thickness and a first curvature adjustment capability on the first wafer by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, such that the absolute value of the first curvature of the first wafer is less than or equal to a first preset value to obtain a first wafer with the first curvature.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and more specifically, to a method for adjusting wafer curvature. Background Technology

[0002] In semiconductor manufacturing, multilayer thin-film deposition and etching are performed on wafers. These processes cause wafer bending, and excessive wafer bending can lead to a series of problems, such as wafer surface layer detachment, wafer breakage, unstable layout alignment, and failure of subsequent process chucks to hold the wafer, ultimately preventing the completion of subsequent processes. All of these issues result in unstable semiconductor product performance and may even reduce yield and output. Therefore, controlling wafer bending within a reasonable range has significant economic benefits and research value. Summary of the Invention

[0003] In view of this, embodiments of this disclosure propose a wafer curvature adjustment method, comprising:

[0004] Provide the first wafer;

[0005] By adjusting the process parameters in the plasma-enhanced chemical vapor deposition (PECVD) process, a first material layer with a first fixed thickness and a first curvature adjustment capability is formed on the first wafer, such that the absolute value of the first curvature of the first wafer is less than or equal to a first preset value.

[0006] The method in the above scheme further includes:

[0007] Multiple test wafers are provided before the first wafer is provided;

[0008] Obtain the second curvature of multiple test wafers;

[0009] On each of the test wafers, a first material layer with a second fixed thickness and adjustable curvature is formed by adjusting the process parameters during plasma-enhanced chemical vapor deposition.

[0010] Obtain the third curvature of the plurality of test wafers after the formation of the first material layer;

[0011] The correspondence between process parameters and bending adjustment capability is obtained based on the second curvature, the second fixed thickness, and the third curvature.

[0012] The method in the above scheme further includes:

[0013] After providing the first wafer, the fourth curvature of the first wafer is obtained;

[0014] The first curvature of the first wafer to be obtained is determined based on the first preset value;

[0015] The value of the first curvature adjustment capability is obtained based on the first fixed thickness, the first curvature, and the fourth curvature.

[0016] Based on the correspondence between process parameters and curvature adjustment capability, and the value of the first curvature adjustment capability, the values ​​of the process parameters required to form the first material layer on the first wafer are obtained.

[0017] In the above scheme, the step of forming a first material layer with a first fixed thickness and a first curvature adjustment capability on the first wafer by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process includes:

[0018] After obtaining the values ​​of the process parameters required to form the first material layer on the first wafer, the process parameters in the plasma-enhanced chemical vapor deposition process are adjusted to the required values ​​to form a first material layer with a first fixed thickness and a first curvature adjustment capability on the first wafer, thereby making the absolute value of the first curvature of the first wafer less than or equal to a first preset value.

[0019] In the above scheme, the first preset value is 200μm.

[0020] In the above scheme, the process parameter is the deposition temperature;

[0021] When the material of the first material layer is silicon nitride, the deposition temperature is greater than 300°C and less than 450°C;

[0022] When the material of the first material layer is silicon oxide, the deposition temperature is greater than 280°C and less than 450°C.

[0023] In the above scheme, the process parameter is radio frequency power;

[0024] When the material of the first material layer is silicon nitride, the radio frequency power is greater than 500W and less than 2000W;

[0025] When the material of the first material layer is silicon oxide, the radio frequency power is greater than 500W and less than 2000W.

[0026] In the above scheme, the first wafer includes a first substrate and a first device layer located on the first substrate, and the first material layer is formed on one side of the first device layer that is away from the first substrate along the thickness direction of the first substrate.

[0027] The method in the above scheme further includes:

[0028] A second wafer is provided, the second wafer including a second substrate and a first dielectric layer located on the second substrate;

[0029] By adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, a second material layer with a third fixed thickness and a second curvature adjustment capability is formed on the first dielectric layer, such that the absolute value of the fifth curvature of the second wafer is less than or equal to the second preset value.

[0030] The method in the above scheme further includes:

[0031] After forming a first material layer on the first wafer, a first contact structure is formed in the first material layer;

[0032] After forming a second material layer on the first dielectric layer, a second contact structure is formed in the second material layer.

[0033] The method in the above scheme further includes:

[0034] After forming the first contact structure and the second contact structure, the first material layer on the first wafer and the second material layer on the second wafer are bonded together to obtain a stacked wafer structure.

[0035] The method in the above scheme further includes:

[0036] On the side of the second substrate away from the second material layer on opposite sides along the thickness direction of the second substrate, a third material layer with a fourth fixed thickness and a third curvature adjustment capability is formed by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, so that the absolute value of the seventh curvature of the stacked wafer structure is less than or equal to the third preset value.

[0037] The method in the above scheme further includes:

[0038] After obtaining the stacked wafer structure, the sixth curvature of the stacked wafer structure is measured; based on the seventh curvature, the sixth curvature, and the fourth fixed thickness, the value of the third curvature adjustment capability is obtained;

[0039] Based on the correspondence between the curvature adjustment capability and the process parameters, and the value of the third curvature adjustment capability, the values ​​of the process parameters required to form the third material layer are obtained.

[0040] In the above scheme, forming the third material layer includes:

[0041] A third material layer is formed, comprising multiple sub-material layers, each with its own fixed thickness and its own curvature adjustment capability;

[0042] Based on the seventh curvature, the sixth curvature, and the fixed thickness of each sub-material layer, the curvature adjustment capability of each sub-material layer can be freely selected.

[0043] The method in the above scheme further includes:

[0044] After obtaining the stacked wafer structure, a third contact structure is formed from the side of the second substrate away from the second material layer on both sides opposite to each other along the thickness direction of the second substrate.

[0045] In this embodiment, by adjusting the process parameters during plasma-enhanced chemical vapor deposition, a first material layer with a first fixed thickness and a first curvature adjustment capability is formed. That is, in this embodiment, with the thickness of the first material layer fixed, the curvature adjustment capability of the first material layer is adjusted by adjusting the process parameters during the deposition process, thereby controlling the first curvature of the first wafer within the required range, so that the first wafer can enter the machine for subsequent process manufacturing. Furthermore, in this embodiment, the thickness of the first material layer is not adjusted. The thickness of the first material layer can be safely set according to product needs, without having to consider the peeling defects caused by depositing a thicker first material layer when adjusting the curvature, thereby improving product performance. Attached Figure Description

[0046] Figure 1 This is a schematic flowchart illustrating a wafer curvature adjustment method provided in an embodiment of the present disclosure.

[0047] Figures 2-9 This is a schematic diagram of a wafer curvature adjustment process provided in an embodiment of the present disclosure. Detailed Implementation

[0048] To make the technical solutions and advantages of the embodiments of this disclosure clearer, the technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. Although exemplary implementation methods of this disclosure are shown in the accompanying drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the implementation methods set forth herein. Rather, these implementation methods are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0049] The present disclosure is described in more detail below by way of example with reference to the accompanying drawings. The advantages and features of the present disclosure will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present disclosure.

[0050] It is understood that the meanings of “on”, “above” and “above” in this disclosure should be interpreted in the broadest sense, such that “on” means not only that it is “on” something without any intervening feature or layer (i.e., directly on something), but also that it is “on” something with an intervening feature or layer.

[0051] Furthermore, for ease of description, spatial relative terms such as “on,” “above,” “above,” “upper,” “above,” “upper,” etc., may be used herein to describe the relationship between one element or feature and another element or feature as shown in the figures. In addition to the orientations depicted in the figures, the spatial relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations) and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0052] In embodiments of this disclosure, the term "substrate" refers to the material on which subsequent material layers are added. The substrate itself may be patterned. The material added on top of the substrate may be patterned or may remain unpatterned. Furthermore, the substrate may include various semiconductor materials, such as silicon, silicon germanium, germanium, gallium arsenide, indium phosphide, etc.

[0053] In embodiments of this disclosure, the term "layer" refers to a portion of material including a region having thickness. A layer may extend over the entirety of a lower or upper structure, or may have a range smaller than that of the lower or upper structure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure with a thickness less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of a continuous structure, or a layer may be located between any horizontal faces at the top and bottom surfaces of a continuous structure. A layer may extend horizontally, vertically, and / or along an inclined surface. A layer may include multiple sublayers. For example, an interconnect layer may include one or more conductor and contact sublayers (where interconnect lines and / or via contacts are formed), and one or more dielectric sublayers.

[0054] In the embodiments of this disclosure, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0055] Most wafer fabrication machines in current factories have strict requirements on the curvature of wafers that can be fabricated on the machine. For example, they can only support wafers with a curvature within + / -200μm. However, for 3D integrated wafers, the curvature of incoming wafers varies greatly, sometimes around +200μm and sometimes around -200μm. This can prevent wafers from entering the machine, thus preventing further processing. Furthermore, in multi-wafer stacking, severely curved chips can affect chip bonding and electrical connections after stacking, thus requiring very strict control over wafer curvature. Currently, for two stacked wafers, if the incoming wafer has an extreme curvature, the common approach is to grow silicon nitride or silicon oxide on the back side of the wafer to maintain the curvature at an acceptable level, allowing subsequent processes to proceed normally.

[0056] For multi-layer stacked wafers, silicon nitride or silicon oxide films cannot be grown indefinitely. Excessive or thick films can lead to peeling defects, affecting device performance. Therefore, effectively controlling wafer curvature and avoiding defects caused by excessive or thick films has become a pressing issue.

[0057] Therefore, to solve the above problems, this disclosure provides a wafer curvature adjustment method, such as... Figure 1 As shown, it includes:

[0058] S1100: Provides the first wafer;

[0059] S1200: By adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, a first material layer with a first fixed thickness and a first curvature adjustment capability is formed on the first wafer, such that the absolute value of the first curvature of the first wafer is less than or equal to a first preset value.

[0060] It is understood that in this embodiment of the present disclosure, by adjusting the process parameters during plasma-enhanced chemical vapor deposition, a first material layer with a first fixed thickness and a first curvature adjustment capability is formed. That is, in this embodiment of the present disclosure, with the thickness of the first material layer fixed, the curvature adjustment capability of the first material layer is adjusted by adjusting the process parameters during the deposition process, thereby controlling the first curvature of the first wafer within the required range, so that the first wafer can enter the machine for subsequent process manufacturing. Furthermore, in this embodiment of the present disclosure, the thickness of the first material layer is not adjusted. The thickness of the first material layer can be safely set according to product needs, without having to consider the peeling defects caused by depositing a thicker first material layer when adjusting the curvature, thereby improving product performance.

[0061] In some specific examples, the size of the first wafer may be different. In practical applications, the diameter of the first wafer may include 150mm, 200mm, 300mm and 450mm, etc., but is not limited to this.

[0062] In some embodiments, such as Figure 2 As shown, the first wafer 101 includes a first substrate 103 and a first device layer 104 located on the first substrate 103.

[0063] In some specific examples, the first substrate 103 may include a single-element semiconductor material substrate (e.g., a silicon (Si) substrate, a germanium (Ge) substrate, etc.), a composite semiconductor material substrate (e.g., a germanium-silicon (SiGe) substrate, etc.), a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GeOI) substrate, etc. Preferably, the first substrate 103 is a silicon substrate.

[0064] In some specific examples, the material of the first device layer 104 includes a dielectric material, specifically silicon nitride or silicon oxide, and a semiconductor device is formed in the first device layer 104.

[0065] In some embodiments, such as Figure 3 As shown, the first material layer 102 is formed on the side of the first device layer 104 that is away from the first substrate 103, opposite to each other on both sides along the thickness direction of the first substrate 103.

[0066] In some specific examples, the material of the first material layer 102 includes silicon nitride and silicon oxide.

[0067] In some embodiments, such as Figure 4 As shown, the method further includes:

[0068] After forming a first material layer 102 on the first wafer 101, a first contact structure 110 is formed in the first material layer 102.

[0069] In some specific examples, the first contact structure 110 is connected to a semiconductor device in the first device layer 104. The method for forming the first contact structure 110 specifically includes: forming a first photoresist layer with a first pattern on the first material layer 102; forming a first via in the first material layer 102 using photolithography and etching processes; depositing a conductive material layer in the first via and on the first material layer 102 using a deposition process; and planarizing the conductive material layer using a chemical mechanical polishing process, so that the surface of the conductive material layer is flush with the surface of the first material layer 102, thereby forming the first contact structure 110.

[0070] In some embodiments, the method further includes:

[0071] Prior to providing the first wafer 101, multiple test wafers are provided;

[0072] Obtain the second curvature of multiple test wafers;

[0073] On each of the test wafers, a first material layer 102 with a second fixed thickness and adjustable curvature is formed by adjusting the process parameters during plasma-enhanced chemical vapor deposition.

[0074] Obtain the third curvature of the plurality of test wafers after the formation of the first material layer 102;

[0075] The correspondence between process parameters and bending adjustment capability is obtained based on the second curvature, the second fixed thickness, and the third curvature.

[0076] In some specific examples, the test wafer needs to be a wafer with the same structure as the first wafer 101.

[0077] Here, the second fixed thickness is the same as the first fixed thickness.

[0078] In some specific examples, when the second fixed thickness is a1, the second curvature is b1, the third curvature is c1, and the curvature adjustment capability of the first material layer 102 is d1, the following formula (1) is satisfied:

[0079] c1=b1+a1*d1 (1)

[0080] Understandably, given that the second curvature, second fixed thickness, and third curvature are measured using measuring tools, the curvature adjustment capability can be calculated using a formula. This allows us to derive the correspondence between process parameters and curvature adjustment capability, meaning we can obtain the specific values ​​of the required process parameters for different curvature adjustment capabilities.

[0081] In some specific examples, the material of the first material layer 102 includes silicon nitride and silicon oxide.

[0082] In some specific examples, when the material of the first material layer is silicon oxide, the range of the curvature adjustment capability of the first material layer is: to When the material of the first material layer is silicon nitride, the range of the bending adjustment capability of the first material layer is: to

[0083] In some embodiments, the method further includes:

[0084] After providing the first wafer 101, the fourth curvature of the first wafer 101 is obtained;

[0085] The first curvature of the first wafer 101 to be obtained is determined according to the first preset value;

[0086] The value of the first curvature adjustment capability is obtained based on the first fixed thickness, the first curvature, and the fourth curvature.

[0087] Based on the correspondence between process parameters and curvature adjustment capability, and the value of the first curvature adjustment capability, the values ​​of the process parameters required to form the first material layer 102 on the first wafer 101 are obtained.

[0088] The fourth curvature here refers to the curvature of the first wafer 101 before the first material layer 102 is formed on the first wafer 101.

[0089] In some embodiments, the first preset value is 200 μm.

[0090] It should be noted that the specific values ​​of the first preset value given in the above embodiments are merely exemplary and are not intended to limit the specific values ​​of the first preset value in the embodiments of this disclosure. In actual applications, the value can be set according to process requirements.

[0091] In some specific examples, the value of the first curvature of the first wafer 101 to be obtained can be determined based on the first preset value, thereby obtaining the value of the process parameters during the deposition process. For example, when the first preset value is 200 μm, a specific value c2 is set to control the first curvature to be less than or equal to 200 μm. Given the first fixed thickness a2 to be deposited in the first material layer 102, the fourth curvature b2 is obtained by measuring tools. The value d2 of the first curvature adjustment capability can be obtained according to the following formula (2). Then, the specific value of the required process parameters can be obtained by the correspondence between the curvature adjustment capability and the process parameters obtained from the experiment.

[0092] c² = b² + a² * d² (2)

[0093] In some embodiments, forming a first material layer 102 with a first fixed thickness and a first curvature adjustment capability on the first wafer 101 by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process includes:

[0094] After obtaining the values ​​of the process parameters required to form the first material layer 102 on the first wafer 101, the process parameters in the plasma-enhanced chemical vapor deposition process are adjusted to the required values ​​to form the first material layer 102 with a first fixed thickness and a first curvature adjustment capability on the first wafer 101, thereby making the absolute value of the first curvature of the first wafer 101 less than or equal to a first preset value.

[0095] In some specific examples, the process parameters include at least one of the following: deposition temperature and radio frequency power.

[0096] In some embodiments, the process parameter is the deposition temperature;

[0097] When the material of the first material layer 102 is silicon nitride, the deposition temperature is greater than 300°C and less than 450°C;

[0098] When the material of the first material layer 102 is silicon oxide, the deposition temperature is greater than 280°C and less than 450°C.

[0099] In some embodiments, the process parameter is radio frequency power;

[0100] When the material of the first material layer 102 is silicon nitride, the radio frequency power is greater than 500W and less than 2000W;

[0101] When the material of the first material layer 102 is silicon oxide, the radio frequency power is greater than 500W and less than 2000W.

[0102] In some specific examples, the first wafer 101 includes a first surface and a second surface along the thickness direction of the first wafer 101. When the first wafer 101 bends toward the first surface, the first material layer 102 is formed on the second surface. Adjusting the absolute value of the first curvature of the first wafer to be less than or equal to a first preset value can include the following two schemes: Scheme 1, the material of the deposited first material layer 102 is silicon oxide, the deposition temperature is adjusted to be greater than 280°C and less than 450°C, and the radio frequency power is adjusted to be greater than 500W and less than 2000W; Scheme 2, the material of the deposited first material layer 102 is silicon nitride, and the radio frequency power is adjusted to be greater than 500W and less than 2000W.

[0103] In some specific examples, the deposition gas source in Scheme 1 includes silane and nitrous oxide, and the flow ratio of silane to nitrous oxide is controlled at 1:10, and the gas pressure is controlled at 10 Torr.

[0104] In some specific examples, the deposition gas source in Scheme 2 includes silane and ammonia, with the flow ratio of silane to ammonia controlled at 1:1, the gas pressure controlled at 10 Torr, and the deposition temperature controlled at 300℃.

[0105] It is understandable that when the first wafer 101 bends toward the first surface and the first material layer 102 is deposited on the second surface, the first material layer 102 needs to have a certain compressive stress so that the first wafer 101 bends toward the second surface under the action of compressive stress, thereby reducing the curvature of the first wafer 101.

[0106] On the one hand, regarding silicon nitride, the higher the radio frequency power, the higher the energy carried by the particles in the plasma, and the easier it is to cause the ion bombardment effect. At the same time, the higher the thin film deposition rate and the more saturated it becomes, the ion bombardment effect and the thin film deposition rate work together to increase the compressive stress of the thin film. Therefore, the higher the radio frequency power, the greater the value of the bending adjustment capability of silicon nitride.

[0107] Regarding silicon oxide, increasing the RF power significantly intensifies the gas-phase reactions between active gaseous particles, accelerating the deposition rate. Particles reaching the substrate surface don't have enough time to align properly before being covered by subsequent particles, increasing the compressive stress of the film. Therefore, higher RF power results in greater flexibility in silicon oxide. When the deposition temperature of silicon oxide is above 280℃ but below 450℃, the activation of disordered substances within the film becomes dominant. These disordered substances gradually decrease as they are promptly rearranged, transforming the film stress into tensile stress. Excessive RF power leads to excessive compressive stress in the film. Therefore, adjusting the deposition temperature can reduce the compressive stress of the silicon oxide film accordingly.

[0108] On the other hand, regarding the deposition temperature of silicon nitride, when the deposition temperature of silicon nitride is greater than 300°C and less than 450°C, the silicon nitride produced has compressive stress. Furthermore, as the deposition temperature increases, the stress of the thin film increases due to the influence of grain growth and thermal stress in the thin film.

[0109] In some specific examples, the first wafer 101 includes a first surface and a second surface along the thickness direction of the first wafer 101. When the first wafer 101 is bent toward the second surface, the first material layer 102 is formed on the second surface. The material of the first material layer 102 is silicon oxide, and the deposition temperature is greater than 280°C and less than 450°C. The deposition gas source includes silane and nitrous oxide, and the flow ratio of silane to nitrous oxide is controlled at 1:10, the gas pressure is controlled at 10 Torr, and the radio frequency power is controlled at 500W.

[0110] Understandably, when the first wafer 101 bends towards the second surface, and the first material layer 102 is deposited on the second surface, the first material layer 102 needs to have a certain tensile stress to allow the first wafer 101 to bend towards the first surface under the action of tensile stress, thereby reducing the curvature of the first wafer 101. When the deposition temperature of silicon oxide is greater than 280℃ and less than 450℃, the activation of disordered substances in the film is dominant. The disordered substances in the film are gradually reduced due to timely rearrangement, and the film stress is transformed into tensile stress. When the RF power is controlled at a low value, such as 500W, the thin film has tensile stress, thus playing a role in adjusting the curvature of the first wafer 101 when it bends towards the second surface.

[0111] In some specific examples, the first material layer 102 may include multiple sub-material layers, each of which adjusts the process parameters during plasma-enhanced chemical vapor deposition during its formation, so that each sub-material layer has its own curvature adjustment capability, and the curvature of the first wafer after deposition of each sub-material layer can be controlled within the required preset value.

[0112] In some embodiments, such as Figure 5 As shown, the method further includes:

[0113] A second wafer 105 is provided, the second wafer 105 including a second substrate 107 and a first dielectric layer 108 located on the second substrate 107;

[0114] By adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, a second material layer 106 with a third fixed thickness and a second curvature adjustment capability is formed on the first dielectric layer 108, such that the absolute value of the fifth curvature of the second wafer 105 is less than or equal to the second preset value.

[0115] In some specific examples, the material of the first dielectric layer 108 includes silicon oxide.

[0116] In some specific examples, the second preset value is 200 μm.

[0117] In some specific examples, the material of the second material layer 106 includes silicon nitride and silicon oxide.

[0118] In some specific examples, the second material layer 106 may include multiple sub-material layers, each of which adjusts the process parameters during plasma-enhanced chemical vapor deposition during its formation, so that each sub-material layer has its own curvature adjustment capability, and the curvature of the second wafer after deposition of each sub-material layer can be controlled within the required preset value.

[0119] In some specific examples, the curvature of the second wafer 105 can be measured first to obtain the eighth curvature b3, and the value of the fifth curvature c3 to be obtained can be set according to the second preset value. The absolute value of c3 is less than or equal to the second preset value. Based on the known third fixed thickness a3, the value of the second curvature adjustment capability of the second material layer d3 to be obtained can be calculated using the following formula (3).

[0120] c3=b3+a3*d3 (3)

[0121] When the material of the second material layer is the same as that of the first material layer, the values ​​of the process parameters required for deposition are obtained based on the correspondence between process parameters and curvature adjustment capability obtained from multiple test wafers, as described above. Therefore, the process parameters are adjusted to the corresponding values ​​during the deposition of the second material layer, resulting in a second wafer with an absolute value of the fifth curvature less than or equal to the second preset value. When the material of the second material layer is different from that of the first material layer, multiple test wafers can be provided again to obtain the ninth curvature of each test wafer. On each test wafer, the process parameters during plasma-enhanced chemical vapor deposition are adjusted to form a second material layer with a third fixed thickness and different curvature adjustment capabilities. The tenth curvature of the multiple test wafers after the formation of the second material layer is obtained. Based on the ninth curvature, the third fixed thickness, and the tenth curvature, the correspondence between the deposition process parameters and curvature adjustment capability during the deposition of the second material layer is obtained.

[0122] In some embodiments, such as Figure 5 As shown, the method further includes:

[0123] After forming a second material layer 106 on the first dielectric layer 108, a second contact structure 111 is formed in the second material layer 106.

[0124] In some specific examples, a metal connection structure is formed in the first dielectric layer 108, and the second contact structure 111 is connected to the metal connection structure in the first dielectric layer 108.

[0125] In some embodiments, the method further includes:

[0126] After forming the first contact structure 110 and the second contact structure 111, the first material layer 102 on the first wafer 101 and the second material layer 106 on the second wafer 105 are bonded to obtain a stacked wafer structure.

[0127] In some specific examples, after the first material layer 102 on the first wafer 101 is bonded to the second material layer 106 on the second wafer 105, the first contact structure 110 is connected to the second contact structure 111.

[0128] In some embodiments, such as Figure 6 As shown, the method further includes:

[0129] After obtaining the stacked wafer structure, a third contact structure 112 is formed from the side of the second substrate 105 away from the second material layer 106 on both sides opposite to each other along the thickness direction of the second substrate 105.

[0130] In some specific examples, the material of the third contact structure 112 includes a conductive material, and the third contact structure 112 can be connected to the metal connection structure in the first dielectric layer 108.

[0131] In some embodiments, such as Figures 7 to 9 As shown, the method further includes:

[0132] On the side of the second substrate 107 opposite to the second material layer 106 along the thickness direction of the second substrate 107, a third material layer 109 with a fourth fixed thickness and a third curvature adjustment capability is formed by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, so that the absolute value of the seventh curvature of the stacked wafer structure is less than or equal to the third preset value.

[0133] In some specific examples, the third preset value can be 0.

[0134] In some specific examples, the material of the third material layer 109 includes silicon nitride and silicon oxide.

[0135] In some embodiments, the method further includes:

[0136] After obtaining the stacked wafer structure, the sixth curvature of the stacked wafer structure was measured;

[0137] The value of the third curvature adjustment capability is obtained based on the seventh curvature, the sixth curvature, and the fourth fixed thickness;

[0138] Based on the correspondence between the curvature adjustment capability and the process parameters, and the value of the third curvature adjustment capability, the values ​​of the process parameters required to form the third material layer 109 are obtained.

[0139] In some embodiments, forming the third material layer 109 includes:

[0140] A third material layer 109 is formed, comprising multiple sub-material layers, each sub-material layer having its own fixed thickness and its own curvature adjustment capability;

[0141] Based on the seventh curvature, the sixth curvature, and the fixed thickness of each sub-material layer, the curvature adjustment capability of each sub-material layer can be freely selected.

[0142] In some specific examples, each sub-material layer in the multilayer submaterial layer is made of silicon nitride and silicon oxide. The materials of the multilayer submaterial layers can be the same or different.

[0143] In some specific examples, such as Figures 7 to 8As shown, forming the third material layer 109 includes forming a first sub-material layer 109-1, a second sub-material layer 109-2, a third sub-material layer 109-3, and a fourth sub-material layer.

[0144] In some specific examples, a semiconductor device connected to the third contact structure 112 may be formed in the first sub-material layer 109-1. A fourth contact structure 113 connected to the semiconductor device in the first sub-material layer 109-1 may be formed in the second sub-material layer 109-2, the third sub-material layer 109-3, and the fourth sub-material layer.

[0145] It is understandable that when the sixth curvature is c4, the fixed thicknesses of the first sub-material layer 109-1, the second sub-material layer 109-2, the third sub-material layer 109-3, and the fourth sub-material layer 109-4 are A1, A2, A3, and A4, respectively. The curvature adjustment capabilities of the first sub-material layer 109-1, the second sub-material layer 109-2, the third sub-material layer 109-3, and the fourth sub-material layer are ΔX1, ΔX2, ΔX3, and ΔX4, respectively. When the seventh curvature needs to be 0, then c4 + A1*ΔX1 + A2*ΔX2 + A3*ΔX3 + A4*ΔX4 ≈ 0 must be satisfied. The curvature adjustment capability of each sub-material layer can be freely selected as needed. Based on the correspondence between the curvature adjustment capability and the process parameters during deposition, the process parameters during deposition are controlled to the required values, so that the seventh curvature of the stacked wafer structure with the third material layer 109 is close to 0. Since the thicknesses of the first, second, and third material layers can be set according to requirements, it is possible to maximize the adjustment of the curvature of the final stacked wafer structure while ensuring that the product does not have peeling defects due to excessive thickness of the first, second, and third material layers, so that the seventh curvature of the stacked wafer structure with the third material layer 109 is controlled within a reasonable range.

[0146] In the several embodiments provided in this disclosure, it should be understood that the disclosed devices and methods can be implemented in a non-target manner. The device embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components may be combined, or integrated into another system, or some features may be ignored or not executed. Furthermore, the various components shown or discussed may be coupled or directly coupled to each other.

[0147] The features disclosed in the several method or device embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new method or device embodiments.

[0148] This disclosure provides specific embodiments, but its scope of protection is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for adjusting wafer curvature, characterized in that, include: Provide the first wafer; By adjusting the process parameters during plasma-enhanced chemical vapor deposition (PECVD), a first material layer with a first fixed thickness and a first curvature adjustment capability is formed on the first wafer, such that the absolute value of the first curvature of the first wafer is less than or equal to a first preset value; the thickness of the first material layer formed on the first wafer is the same under different curvatures; the first curvature adjustment capability of the first material layer with the first fixed thickness is adjusted by adjusting the process parameters during the PECVD process; the first material layer includes multiple sub-material layers, each sub-material layer having its own fixed thickness, and the process parameters during the PECVD process are adjusted for each sub-material layer during formation, so that each sub-material layer has its own curvature adjustment capability, such that the absolute value of the curvature of the first wafer after deposition is less than or equal to the required preset value.

2. The method according to claim 1, characterized in that, The method further includes: Multiple test wafers are provided before the first wafer is provided; Obtain the second curvature of multiple test wafers; On each of the test wafers, a first material layer with a second fixed thickness and adjustable curvature is formed by adjusting the process parameters during plasma-enhanced chemical vapor deposition. Obtain the third curvature of the plurality of test wafers after the formation of the first material layer; The correspondence between process parameters and bending adjustment capability is obtained based on the second curvature, the second fixed thickness, and the third curvature.

3. The method according to claim 2, characterized in that, The method further includes: After providing the first wafer, the fourth curvature of the first wafer is obtained; The first curvature of the first wafer to be obtained is determined based on the first preset value; The value of the first curvature adjustment capability is obtained based on the first fixed thickness, the first curvature, and the fourth curvature. Based on the correspondence between process parameters and curvature adjustment capability, and the value of the first curvature adjustment capability, the values ​​of the process parameters required to form the first material layer on the first wafer are obtained.

4. The method according to claim 3, characterized in that, The method of forming a first material layer with a first fixed thickness and a first curvature adjustment capability on the first wafer by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process includes: After obtaining the values ​​of the process parameters required to form the first material layer on the first wafer, the process parameters in the plasma-enhanced chemical vapor deposition process are adjusted to the required values ​​to form the first material layer with the first fixed thickness and the first curvature adjustment capability on the first wafer, so that the absolute value of the first curvature of the first wafer is less than or equal to the first preset value.

5. The method according to claim 1, characterized in that, The first preset value is 200μm.

6. The method according to claim 1, characterized in that, The process parameter is the deposition temperature; When the material of the first material layer is silicon nitride, the deposition temperature is greater than 300°C and less than 450°C; When the material of the first material layer is silicon oxide, the deposition temperature is greater than 280°C and less than 450°C.

7. The method according to claim 1, characterized in that, The process parameter is radio frequency power; When the material of the first material layer is silicon nitride, the radio frequency power is greater than 500W and less than 2000W; When the material of the first material layer is silicon oxide, the radio frequency power is greater than 500W and less than 2000W.

8. The method according to claim 1, characterized in that, The first wafer includes a first substrate and a first device layer located on the first substrate, wherein the first material layer is formed on one side of the first device layer opposite to the first substrate along the thickness direction of the first substrate, away from the first substrate.

9. The method according to claim 8, characterized in that, The method further includes: A second wafer is provided, the second wafer including a second substrate and a first dielectric layer located on the second substrate; By adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, a second material layer with a third fixed thickness and a second curvature adjustment capability is formed on the first dielectric layer, such that the absolute value of the fifth curvature of the second wafer is less than or equal to the second preset value.

10. The method according to claim 9, characterized in that, The method further includes: After forming the first material layer on the first wafer, a first contact structure is formed in the first material layer; After forming the second material layer on the first dielectric layer, a second contact structure is formed in the second material layer.

11. The method according to claim 10, characterized in that, The method further includes: After forming the first contact structure and the second contact structure, the first material layer on the first wafer and the second material layer on the second wafer are bonded together to obtain a stacked wafer structure.

12. The method according to claim 11, characterized in that, The method further includes: On the side of the second substrate away from the second material layer on opposite sides along the thickness direction of the second substrate, a third material layer with a fourth fixed thickness and a third curvature adjustment capability is formed by adjusting the process parameters in the plasma-enhanced chemical vapor deposition process, so that the absolute value of the seventh curvature of the stacked wafer structure is less than or equal to the third preset value.

13. The method according to claim 12, characterized in that, The method further includes: After obtaining the stacked wafer structure, the sixth curvature of the stacked wafer structure was measured; The value of the third curvature adjustment capability is obtained based on the seventh curvature, the sixth curvature, and the fourth fixed thickness; Based on the correspondence between the curvature adjustment capability and the process parameters, and the value of the third curvature adjustment capability, the values ​​of the process parameters required to form the third material layer are obtained.

14. The method according to claim 13, characterized in that, The formation of the third material layer includes: The third material layer is formed, comprising multiple sub-material layers, each sub-material layer having its own fixed thickness and its own curvature adjustment capability; Based on the seventh curvature, the sixth curvature, and the fixed thickness of each of the sub-material layers, the curvature adjustment capability of each of the sub-material layers can be freely selected.

15. The method according to claim 11, characterized in that, The method further includes: After obtaining the stacked wafer structure, a third contact structure is formed from the side of the second substrate away from the second material layer on both sides opposite to each other along the thickness direction of the second substrate.

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