Real-time monitoring method and real-time monitoring apparatus for wafer warpage

Abstract

The present invention relates to the technology of semiconductor chip manufacturing, and more specifically, to a real-time monitoring method and real-time monitoring apparatus for wafer warpage. In the process of depositing a thin film on a wafer, the rate of change of heating power in each heating region of a heating tray is monitored in real time, where the heating tray includes at least two heating regions, each heating region is in a set constant temperature control state, a wafer is placed in the at least two heating regions, and the wafer has wafer regions corresponding to each of the heating regions, and it is determined whether the corresponding wafer region has moved out of the heating tray based on the rate of change of heating power. In the thin film deposition process, by monitoring the change in heating power, the amount of change in wafer warpage can be monitored in real time without using additional measuring equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor chip manufacturing, and more specifically, to a method and apparatus for real-time monitoring of wafer warpage.

Background Art

[0002] In the manufacturing process of semiconductor chips, various dielectric layers, metal layers, etc. are often deposited using the plasma-enhanced chemical vapor deposition (PECVD) method. The manipulator places the wafer on the heating tray in the chamber, and the reaction gas enters the chamber through the shower head directly above the heating tray. Under the action of radio frequency, plasma is formed, and the reaction ions move to the wafer surface to react, forming a thin film such as silicide on the wafer surface.

[0003] In the thin film deposition process, since the thermal expansion coefficients of the newly formed thin film and the wafer substrate are different, stress is generated between the two, resulting in warping deformation of the wafer.

[0004] If the thin film stress is large, especially when the thin film thickness is thick, the warpage of the wafer will be large and a part of it will detach from the heating tray, resulting in a decrease in heating efficiency, poor film quality uniformity, and in some cases, the risk of arc generation.

[0005] Currently, in the industry, the thin film stress is mainly monitored by measuring instruments before and after film formation and controlled within a certain range, but the deformation situation of the wafer during the film formation process cannot be monitored in real time.

Summary of the Invention

[0006] In view of the above problems, the present invention aims to provide a method and apparatus for real-time monitoring of wafer warpage to monitor the warpage situation of the wafer in real time during the film formation process.

[0007] To achieve the above object, the present invention provides the following technical solutions.

[0008] Depending on the circumstances, the gas may be continuously supplied to the etching solution during the aforementioned gas supply period.

[0009] A real-time monitoring method for wafer warpage, comprising: monitoring in real time the rate of change ΔP / P0 of the heating power of each heating region in a heating tray during the process of depositing a thin film on a wafer, where ΔP is the amount of change in the heating power of the heating region and P0 is the heating power of the heating region in its initial state; the heating tray includes at least two heating regions, each heating region is in a set constant temperature control state, a wafer is placed in the at least two heating regions, the wafer has wafer regions corresponding to each of the heating regions, and determining whether the corresponding wafer region has detached from the heating tray based on the rate of change ΔP / P0 of the heating power.

[0010] The present invention provides a real-time monitoring method for wafer warpage, which involves monitoring the change in wafer warpage ΔBOW in real time during the process of depositing a thin film on a wafer. When the change in wafer warpage ΔBOW exceeds a preset threshold, the process conditions to be changed are determined based on the mapping relationship between the change in wafer warpage ΔBOW and the process conditions, and the wafer is processed using the changed process conditions so that the wafer warpage is controlled to stay within the target warpage range.

[0011] The present invention provides a real-time monitoring device for wafer warpage, comprising: a memory configured to store at least one mapping relationship which is a mapping relationship between the amount of change in wafer warpage ΔBOW and process conditions; a monitor configured to monitor the amount of change in wafer warpage ΔBOW in real time; a controller configured to receive the amount of change in wafer warpage ΔBOW and, when the amount of change in wafer warpage ΔBOW exceeds a preset threshold, to determine the process conditions to be changed based on the mapping relationship between the amount of change in wafer warpage ΔBOW and process conditions; and an operator configured to receive the changed process conditions and process the wafer using the changed process conditions.

[0012] The present invention has the following beneficial effects compared to the prior art.

[0013] By applying this invention, the wafer's warping condition, i.e., the change in wafer warping ΔBOW, can be monitored in real time during the thin film deposition process, eliminating the need for additional measuring equipment. [Brief explanation of the drawing]

[0014] To more clearly explain embodiments of the present invention or the technical considerations in the prior art, the following is a brief introduction of the drawings necessary for describing the embodiments or the prior art. However, the drawings in the following description represent only a few embodiments of the present invention, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without paying any inventive labor. Figure 1 is a flowchart of a method for monitoring wafer warpage in real time according to Embodiment 1 of the present invention. Figure 2 is a schematic diagram 1 of the heating state of a wafer by a heating tray according to Embodiment 1 of the present invention. Figure 3 is a schematic diagram 2 of the heating state of a wafer by a heating tray according to Embodiment 1 of the present invention. Figure 4 is a schematic diagram 3 of the heating state of a wafer by a heating tray according to Embodiment 1 of the present invention. Figure 5 is a fitting curve diagram showing the relationship between the change in heating power and warping of the internal heating coil and external heating coil according to Embodiment 1 of the present invention. Figure 6 is a flowchart of a method for monitoring wafer warpage in real time according to Embodiment 2 of the present invention. Figure 7 is a schematic diagram of a thin-film deposition apparatus according to Embodiment 2 of the present invention. Figures 8 to 13 show the relationship between thin film stress and process conditions according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0015] To provide a clearer explanation of the technical considerations of the embodiments of this application, the drawings necessary for describing the embodiments are briefly introduced below. Clearly, the drawings in the following description are merely illustrative or embodiments of the application, and those skilled in the art may apply the application to other similar scenarios based on these drawings, without paying any inventive labor. Unless otherwise stated or as is evident from the locale, identical reference numerals in the drawings represent identical structures or functions.

[0016] As set forth in this application and claims, unless the context explicitly indicates an exception, terms such as “one,” “one,” “one kind,” and / or “the said” do not refer to a singular number but may include multiple numbers. Generally speaking, the terms “equipment” and “includes” merely indicate that explicitly identified steps or elements are included, and these steps or elements do not constitute an exclusive list, and the method or equipment may include other steps or elements.

[0017] The relative arrangements, numerical expressions, and numerical values ​​of the parts and steps described in these embodiments do not limit the scope of this application unless otherwise specified. It should be understood that, for ease of explanation, the dimensions of the parts shown in the drawings are not based on actual proportional relationships. Known art, methods, and equipment to those skilled in the art may not be discussed in detail, but where appropriate, such art, methods, and equipment should be considered part of the patented specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely illustrative and not limiting. Therefore, other examples of exemplary embodiments may have different values. Similar reference numerals and letters represent similar terms in subsequent drawings; therefore, once a term is defined in a drawing, it is not necessary to discuss it further in subsequent drawings.

[0018] In the description of this application, the directional terms such as "front, back, up, down, left, right," "side, up, vertical, horizontal," and "top, bottom" refer to directions or positional relationships that are usually based on the directions or positional relationships shown in the drawings. These terms are used solely to facilitate and simplify the description of this application, and unless otherwise stated, they do not indicate or imply that a particular device or element has a particular direction or must be configured and operate in a particular direction. Therefore, they cannot be understood as limitations on the scope of protection of this application, and the directional terms "inside" and "outside" refer to the inside and outside of the contour of each part itself.

[0019] For the sake of clarity, we may use spatially relative terms such as "above," "above," "on the top surface," or "on the top surface" to describe the spatial relationship between one part or feature and another part or feature, as shown in the diagram. It should be understood that spatially relative terms are intended to include different orientations in use or operation of the part other than the orientation described in the drawing. For example, if the parts in the drawing are inverted, a part described as "above another part or component" or "on top of another part or component" is defined as "below another part or component" or "below another part or component." Thus, the exemplary term "above" can include two orientations: "above" and "below." This part may also be positioned in other different ways (90-degree rotation or other orientations), and the spatially relative descriptions used here can be appropriately explained.

[0020] In addition, the use of terms such as "first" and "second" to limit components is only for the purpose of facilitating the distinction of corresponding components. Without a separate statement, the above terms have no special meaning, and it is necessary to explain that they cannot be understood as limitations to the protection scope of the present application. Also, the terms used in the present application are selected from well-known terms, but some terms described in the specification of the present application are selected by the applicant at his own discretion, and their specific meanings are described in the relevant parts of the description of this specification. Moreover, it is required to understand the present application not only through the actually used terms but also through the meanings included in each term.

[0021] Hereinafter, the technical concept of the present invention will be further described in connection with the drawings using specific embodiments.

[0022] Embodiment 1 Referring to FIG. 1, this embodiment provides a method for real-time monitoring of the warp of a wafer. The method of this embodiment includes the following steps.

[0023] Step S110: In the process of depositing a thin film on the wafer, the change rate ΔP / P0 of the heating power of each heating region in the heating tray is monitored in real time, where ΔP is the change amount of the heating power of the heating region, P0 is the heating power of the heating region in the initial state, the heating tray includes at least two heating regions, each heating region is in a set constant temperature control state, the wafer is arranged in at least two heating regions, and the wafer has a wafer region corresponding to each heating region.

[0024] Step S120: Based on the change rate ΔP / P0 of the heating power, it is determined whether the corresponding wafer region has detached from the heating tray.

[0025] Steps S110 and S120 described above will now be explained with reference to Figures 2 to 5. Referring again to Figure 2, in the thin film deposition process, the wafer 2 is positioned on the heating tray 1, and the heating tray 1 heats the wafer 2. The heating tray 1 comprises a central heating region 11 and an edge heating region 12 located on the outer periphery of the central heating region 11. The heating tray 1 heats the wafer 2 in a dual-zone manner. The edge heating region 12 is equipped with an outer heating coil for heating the portion of the wafer located on the edge heating region 12, and the central heating region 11 is equipped with an inner heating coil for heating the portion of the wafer located on the central heating region 11. Together, the edge heating region 12 and the central heating region 11 heat the entire wafer 2. The inner heating coil and the outer heating coil dynamically adjust the heating power to maintain each heating region in the heating tray 1 in a set constant temperature control state.

[0026] For example, if the temperature of the heating area is lower than the set temperature, the heating power is increased or decreased by a relay.

[0027] In the thin-film deposition process, if no warping occurs in the wafer 2, that is, as shown in Figure 2, the wafer 2 is flat overall, the central part of the wafer 2 is in contact with the central heating region 11, and the edge of the wafer 2 is in contact with the edge heating region 12.

[0028] However, if the wafer 2 warps, a portion of the wafer will detach from the heating tray 1, i.e., it will no longer be in contact with the heating tray 1. In the real-time monitoring method for wafer warping of this embodiment, the warping state of the wafer is determined from the rate of change of heating power ΔP(C) / P0(C) of the central heating region 11 and the rate of change of heating power ΔP(E) / P0(E) of the edge heating region 12. Here, ΔP(C) is the amount of change of heating power corresponding to the central heating region, ΔP(E) is the amount of change of heating power corresponding to the edge heating region, P0(C) is the heating power corresponding to the central heating region in the initial state, and P0(E) is the heating power corresponding to the edge heating region in the initial state.

[0029] Referring to Figure 3, when the contact between the edge of the wafer 2 and the edge heating region 12 of the heating tray 1 decreases, the load on the outer heating coil decreases in order to maintain the set temperature, the heating power of the edge heating region 12 decreases, the heating power of the central heating region 11 remains unchanged, and |ΔP(C) / P0(C)|<|ΔP(E) / P0(E)| occurs, causing the wafer 2 to warp upward in a bowl shape.

[0030] Referring to Figure 4, when the contact between the center of the wafer 2 and the central heating region 11 of the heating tray 1 decreases, the load on the inner heating coil decreases, the heating power of the central heating region 11 decreases, and |ΔP(C) / P0(C)|>|ΔP(E) / P0(E)| occurs, causing the wafer 2 to warp downwards in a bowl shape. Note that the range of change in the heating power of the heating coil will also differ depending on the degree of warping of the wafer 2.

[0031] In this application, the warp of wafer 2 is expressed by the BOW value. The warp state of wafer 2 can be distinguished by the positive and negative BOW values ​​of the wafer's warp. Referring to Figures 3 and 4, if the top surface of wafer 2 is the front surface and the bottom surface is the back surface, the warp state of wafer 2 is as follows: As shown in Figure 4, the edges of wafer 2 are curved toward the back surface and the central part is protruding, that is, wafer 2 is warped downwards, and the BOW value of the wafer's warp is defined as a negative value. Alternatively, as shown in Figure 3, the edges of wafer 2 are curved toward the front surface and the central part is concave, that is, wafer 2 is warped upwards, and the BOW value of the wafer's warp is defined as a positive value.

[0032] For example, the heating tray 1 is not limited to having two heating regions, but may have multiple heating regions, each of which is used to heat the wafer 2.

[0033] According to steps S110 and S120, the method disclosed herein monitors the rate of change ΔP / P0 of the heating power in each heating region in real time and determines whether a portion of the wafer 2 corresponding to that heating region has detached from the heating tray 1 based on the rate of change ΔP / P0 of the heating power. For example, the determination is made from the magnitude of the rate of change ΔP / P0 of the heating power, and if the rate of change ΔP / P0 of the heating power is less than a certain value, it indicates that the portion of the wafer 2 has detached from the heating tray 1.

[0034] In some embodiments, if ΔP / P0 < 0 in a certain heating region, it indicates that the heating power in that region has changed, and means that the portion of the wafer corresponding to the heating region has detached from the heating tray 1.

[0035] In the embodiments disclosed herein, the warpage state of the wafer 2 is not limited to the two states described above. For example, the warpage state of the entire wafer 2 is determined from the rate of change ΔP / P0 of the heating power across all heating regions. The warpage state of the wafer 2 may be saddle-shaped or other special shapes.

[0036] Further investigation revealed a correspondence between the rate of change of heating power in the heating region ΔP / P0 and the change in wafer warp ΔBOW. The change in wafer warp ΔBOW is calculated from the correspondences ΔP(C) / P0(C)=f1'(ΔBOW) and ΔP(E) / P0(E)=f2'(ΔBOW), where f1' represents the relationship between ΔP(C) / P0(C) and ΔBOW, and f2' represents the relationship between ΔP(E) / P0(E) and ΔBOW. f1' and f2' may be functions such as linear or quadratic functions, and this application is not limited to them. When ΔBOW exceeds a preset threshold, a reminder signal is triggered and sent to the controller. After receiving the reminder signal, the controller can adjust the wafer warp.

[0037] For example, the change in wafer warpage ΔBOW is the difference between the current wafer warpage and the initial warpage of wafer 2. The change in heating power ΔP is the difference between the current heating power of the heating region and the heating power of the heating region in the initial state.

[0038] The above correspondences are established based on experiments. The experiments may include the following steps:

[0039] As an example, a heating tray 1 having a central heating region 11 and an edge heating region 12 is placed in a chamber, and a wafer 2 without a thin film deposition is placed on the heating tray 1. After the temperature of the wafer 2 stabilizes at the target process temperature and the chamber stabilizes at the target process temperature, target pressure, target gas flow rate, etc., the average heating power P0'(C) and P0'(E) of the inner heating coil and outer heating coil of the heating tray 1 over a certain period of time are collected. At this time, the wafer 2 is in a flat state and the wafer warp BOW0 value is 0. Here, P0'(C) may be the heating power corresponding to the central heating region in the initial state, and P0'(E) may be the heating power corresponding to the edge heating region in the initial state.

[0040] A first layer of silicon nitride thin film of known thickness is deposited on wafer 2. At this time, wafer 2 is bent upward (or downward), the wafer warp BOW1 is known, and after wafer 2 has stabilized under conditions such as process temperature, target pressure, and target airflow, the average heating power P1(C) and P1(E) of the inner heating coil and outer heating coil of heating tray 1 over a certain period of time are collected.

[0041] Furthermore, a second layer of the same silicon nitride thin film is deposited on wafer 2. At this time, the BOW2 of the wafer warp is known, and the average heating power P2(C) and P2(E) of the inner heating coil and outer heating coil of heating tray 1 over a certain period of time are collected.

[0042] By analogy, after depositing n known film layers on wafer 2, BOW n The average heating power P of the inner heating coil and outer heating coil of the heating tray 1 over a certain period of time is known to be the same as the average heating power P of the inner heating coil and outer heating coil of the heating tray 1 over a certain period of time. n(C), P n Collect (E).

[0043] Referring to Figure 5, the relationship between the heating power of the inner and outer heating coils of the heating tray 1 and the change in the BOW value of the wafer's warp can be obtained by fitting, i.e., P(C)=f1(BOW) and P(E)=f2(BOW). Here, f1 represents the relationship between P(C) and BOW, and f2 represents the relationship between P(E) and BOW. f1 and f2 may be functions such as linear or quadratic functions, but this application is not limited to these. Note that f1' is different from f1, and f2' is different from f2.

[0044] In the thin film deposition process, the heating power of the heating tray 1 is affected not only by changes in heat transfer due to the warping of the wafer 2, but also by the thermal effects of the plasma field, chemical reactions, flow field, and heat field acting on the wafer 2 during the PECVD deposition process. After the thermal effects stabilize, the thermal effects of the plasma field, chemical reactions, flow field, and heat field tend to become constant, and at this time, the change in the heating power of the heating tray 1 is mainly influenced by the change in the BOW value of the wafer warp. When considering thermal effects, the relationship between the heating power of the inner and outer heating coils of the heating tray 1 and the change in the BOW value of the wafer warp can be expressed as follows.

[0045] P(C) = f1(BOW) + C1 and P(E) = f2(BOW) + C2, where C1 and C2 are heating power constants representing the influence of the plasma field, chemical reaction, flow field, and heat field on the central heating region 11 and the edge heating region 12, respectively.

[0046] In this method, the process of depositing a thin film on a wafer includes a PECVD deposition process. In this process, each time a thin film is deposited, the plasma field, chemical reaction, flow field, and heat field act on the wafer 2, causing a thermal effect. The heat release in the thin film deposition process is divided into three stages: first, the first deposition fluctuation stage; second, the deposited thin film stabilization stage; and finally, the second deposition fluctuation stage. Here, a stable thermal effect means that the deposited thin film is in a stable state. Based on these embodiments, step S110 is executed only when it is determined that the thin film deposition reaction is in the deposited thin film stabilization stage, in which the rate of change ΔP / P0 of the heating power of each heating region in the heating tray 1 is monitored in real time.

[0047] In some embodiments, the method includes a CVD deposition process for depositing a thin film on a wafer, in which each time a thin film is deposited, chemical reactions, flow fields, and heat fields act on the wafer 2, causing thermal effects. After the thin film deposition reaction stabilizes, the thermal effects due to chemical reactions, flow fields, and heat fields tend to become constant, and at this time, changes in the heating power of the heating tray 1 are mainly influenced by changes in the BOW value of the wafer's warp. Based on these embodiments, the step of monitoring the rate of change ΔP / P0 of the heating power in each heating region of the heating tray 1 in real time is performed only when it is determined that the thin film deposition reaction has reached the deposited thin film stabilization stage. P(C)=f1(BOW)+C3 and P(E)=f2(BOW)+C4, where C3 and C4 are heating power constants representing the effects of chemical reactions, flow fields, and heat fields on the central heating region 11 and the edge heating region 12, respectively.

[0048] In the CVD deposition process, heat release during the thin film deposition process can be divided into three stages: first, the primary deposition fluctuation stage; second, the deposited thin film stabilization stage; and finally, the secondary deposition fluctuation stage. Here, a stable thermal effect means that the deposited thin film is stable.

[0049] To determine the change in heating power, the initial heating power P0 is subtracted from the current heating power P, thereby removing the constant terms C1 to C4 in the above equation. This eliminates the thermal influences of the plasma field, chemical reactions, flow field, heat field, etc.

[0050] For example, ΔP(C) = (f1(BOW) + C1) - (f1(BOW0) + C1) = f1(BOW) - f1(BOW0), where BOW0 is the initial warp of wafer 2.

[0051] Since ΔP(C) / P0(C)=f1'(ΔBOW), The equation f1'(ΔBOW)=(f1(BOW)-f1(BOW0)) / P0(C) is used as an example to represent the relationship between f1 and f1'.

[0052] In the deposition thin film process, from the deposition thin film stabilization stage, the heating power P(E) of the central heating region and the heating power P(C) of the edge heating region are read every x seconds during that time, thereby monitoring ΔP(C) / P0(C) and ΔP(E) / P0(E) in real time. The correspondence between ΔP(C) / P0(C)=f1'(ΔBOW) and ΔP(E) / P0(E)=f2'(ΔBOW) is determined, and the change in wafer warp ΔBOW is calculated from ΔP(C) and ΔP(E). When ΔBOW exceeds a preset threshold, a reminder signal is triggered and sent to the controller. Here, f1' represents the relationship between ΔP(C) / P0(C) and ΔBOW, and f2' represents the relationship between ΔP(E) / P0(E) and ΔBOW.

[0053] Based on the above, the method for monitoring the warpage of the wafer does not require additional measuring equipment and directly utilizes the changes in heating power of the inner and outer heating coils of the heating tray 1 itself to calculate the amount of change in wafer warpage ΔBOW in real time.

[0054] In some embodiments, when the change in wafer warp ΔBOW exceeds a preset threshold, a reminder signal is triggered and sent to the controller. The method then further determines the process conditions to be changed based on the mapping relationship between the change in wafer warp ΔBOW and the process conditions, and processes the wafer based on the changed process conditions so that the wafer warp is controlled to stay within a target warp range.

[0055] Embodiment 2 As shown in Figure 6, this embodiment provides a method for monitoring the warpage of wafer 2 in real time, and comprises the following steps.

[0056] Step S210: In the process of depositing a thin film on a wafer, the change in wafer warpage ΔBOW is monitored in real time.

[0057] Step S220: When the change in wafer warpage ΔBOW exceeds a preset threshold, the process conditions to be changed are determined based on the mapping relationship between the change in wafer warpage ΔBOW and the process conditions, and the wafer is processed using the changed process conditions so that the wafer warpage is controlled to stay within the target warpage range.

[0058] When the warpage of wafer 2 is within the target warpage range, the stress distribution across wafer 2 is relatively uniform, and wafer 2 is relatively flat, thus ensuring that subsequent semiconductor manufacturing processes proceed smoothly. The warpage of wafer 2 is expressed in terms of the BOW value.

[0059] The following describes, in general terms, a method for adjusting the warpage of wafer 2 provided in this application, using a thin-film deposition apparatus as an example.

[0060] Referring to Figure 7, the thin-film deposition apparatus comprises a chamber for thin-film deposition, a gas supply assembly 3 for supplying process gas into the chamber, a heating tray 1 positioned below the gas supply assembly 3 for heating a wafer 2, and a radio frequency source that supplies radio frequency power to excite the process gas inside the chamber, dissociate it into plasma, and form a plasma field 4. The plasma deposits a thin film on the wafer 2. This application does not limit the installation position of the gas supply assembly 3, and in some embodiments, the gas supply assembly 3 may be provided on the top wall inside the chamber.

[0061] In step S220, the mapping relationship between the change in wafer warpage ΔBOW and the process conditions includes a first correspondence and a second correspondence. Here, the first correspondence is the relationship between the change in wafer warpage ΔBOW and the thin-film stress.

[0062] For example, the change in wafer warpage ΔBOW is positively correlated with the absolute value of the thin-film stress. That is, ΔBOW increases as the thin-film stress increases.

[0063] The second correspondence is the relationship between thin film stress and process conditions.

[0064] For example, a thin film is deposited on wafer 2, and the thin film stress may be divided into tensile stress and compressive stress. When wafer 2 warps upward, the corresponding thin film stress is tensile stress, and when wafer 2 warps downward, the corresponding thin film stress is compressive stress.

[0065] For example, if wafer 2 warps downwards, the wafer warp BOW is defined as a negative value, and if wafer 2 warps upwards, the wafer warp BOW value is defined as a positive value.

[0066] The process conditions in step S220 include, but are not limited to, one or more combinations of the following: gas flow rate, radio frequency power (RF power), chamber pressure (Pressure), gas distribution ratio, thin film deposition time, terminal matching parameters, and distance (Spacing) between the gas supply assembly 3 and the wafer 2.

[0067] Exemplary examples of terminal matching parameters include, but are not limited to, adjustable capacitance (C) and frequency matchers. By changing the potential of the heating tray 1 using the adjustable capacitance (C), the potential difference between the gas supply assembly 3 and the heating tray 1 is adjusted, and further, the distribution and energy magnitude of the plasma field 4 in the chamber are adjusted, thereby changing the impact force that the plasma exerts on the wafer 2, and changing the thin-film stress when the plasma deposits a thin film on the wafer 2.

[0068] The frequency matcher is mounted at the rear end of the radio frequency source and is adjusted to match the frequency of the radio frequency source's transmission power supply with the frequency of the chamber. The inside of the chamber is a vacuum environment.

[0069] For example, thin-film stress is positively correlated with thin-film deposition time. That is, the longer the thin-film deposition time, the thicker the film layer becomes, and the corresponding thin-film stress increases.

[0070] Different film materials (silicon nitride / silicon oxide / a-Si / carbon, etc.), different processes, and different composition ratios (recipe) result in different response directions and sensitivities to process conditions.

[0071] For example, in the second correspondence, the thin-film stress may change in response to changes in process conditions. The relationship between thin-film stress and process conditions may be linear. Of course, the relationship between thin-film stress and process conditions may also be nonlinear, specifically related to the influence that process conditions have on the thin-film stress.

[0072] Taking silicon nitride film layers as an example, the silicon nitride film layer is deposited by filling a chamber with silane (SiH4), ammonia gas (NH3), and nitrogen gas (N2) in constant proportions and flow rates, maintaining a set pressure and temperature, and forming a plasma using radio frequency (RF). Experiments are conducted by adjusting the process conditions, and the stress and refractive index (RI) of the film layer are monitored in real time. Both stress and refractive index (RI) are attributes of the film layer. When depositing a certain type of film layer, the purpose of adjusting the process conditions is to change the stress, but the refractive index (RI), which is an attribute of the film layer, remains unchanged. For details, please refer to Figures 8 to 13. Note that the unit of stress is MPa.

[0073] As shown in Figure 8, there is a positive correlation between thin-film stress and SiH4 flow rate; that is, thin-film stress increases with increasing SiH4 flow rate. There is also a positive correlation between refractive index (RI) and SiH4 flow rate; that is, refractive index (RI) increases with increasing SiH4 flow rate. Here, the unit of flow rate is sccm, and the flow rate units for the following different gases are all the same.

[0074] As shown in Figure 9, there is a positive correlation between thin-film stress and NH3 flow rate; that is, thin-film stress increases with increasing NH3 flow rate. There is a negative correlation between refractive index (RI) and NH3 flow rate.

[0075] As shown in Figure 10, there is a negative correlation between thin-film stress and N2 flow rate; that is, thin-film stress decreases as the N2 flow rate increases. There is a positive correlation between refractive index (RI) and N2 flow rate.

[0076] As shown in Figure 11, there is a negative correlation between thin-film stress and radio frequency power; that is, thin-film stress decreases as radio frequency power increases. There is a positive correlation between refractive index (RI) and radio frequency power. Here, the unit of RF power is watts (W).

[0077] As shown in Figure 12, there is a positive correlation between thin-film stress and chamber pressure; that is, thin-film stress increases with increasing chamber pressure. There is a negative correlation between refractive index (RI) and chamber pressure. Here, the unit of chamber pressure is Torr.

[0078] As shown in Figure 13, there is a positive correlation between thin-film stress and the distance (spacing) between the gas supply assembly 3 and the wafer 2; that is, thin-film stress increases with increasing distance (spacing). There is a negative correlation between refractive index (RI) and distance (spacing). Here, the unit of distance is mil.

[0079] The change in wafer warpage ΔBOW is adjusted by adjusting the thin film stress according to the relationship between the thin film stress and the process conditions described above. For example, if the change in wafer warpage ΔBOW exceeds a preset threshold, the thin film stress value can be reduced by decreasing the SiH4 flow rate and reducing the distance (spacing). This changes the thin film stress from tensile stress to compressive stress, thereby reducing the change in wafer warpage ΔBOW or making ΔBOW = 0 while keeping the RI constant.

[0080] Thin film attributes include thin film stress (Stress), refractive index (RI), etching rate (ER), extinction coefficient (EC), and dielectric constant (k). By examining the relationship between these attributes and process conditions using experiments, if it is necessary to adjust the thin film stress without changing other attributes, the process conditions that need to be adjusted can be calculated from the above relationship.

[0081] Some embodiments include a step of obtaining the BOW value of the wafer warp in real time and obtaining the change in wafer warp ΔBOW based on the BOW value of the wafer warp, prior to step S210 of monitoring the change in wafer warp ΔBOW in real time.

[0082] In the process of depositing a thin film on a wafer, one first film layer and one second film layer are deposited alternately to form a laminated structure. The first film layer has tensile stress, and the second film layer has compressive stress. The BOW value of the wafer's warp is acquired in real time, and the warp state of the laminated structure is adjusted by changing the thickness of one of the film layers by adjusting the thin film deposition time.

[0083] For example, if the first film layer is a SiN film layer and the second film layer is an SiO2 film layer, and the wafer warpage is controlled to stay within the target warpage range, then if the BOW value of the wafer warpage is positive, the average thickness of the subsequent SiO2 film layer is increased or the average thickness of the subsequent SiN film layer is decreased; if the BOW value of the wafer warpage is negative, then the average thickness of the subsequent SiN film layer is increased or the average thickness of the subsequent SiO2 film layer is decreased.

[0084] The first film layer is a single film layer that exhibits tensile stress, and the second film layer is a single film layer that exhibits compressive stress. The first and second film layers may contain multiple film layers or a single film layer, but there is no limitation on the number of film layers.

[0085] Selectively, the heating tray 1 has at least two heating regions, and in step S210, the change in wafer warpage ΔBOW is monitored according to the rate of change ΔP / P0 of the heating power of the heating regions.

[0086] For example, the heating tray 1 comprises a central heating region 11 and an edge heating region 12 provided on the outer periphery of the central heating region 11. Specifically, step S210 monitors the rate of change ΔP(C) / P0(C) of the heating power of the central heating region 11 and the rate of change ΔP(E) / P0(E) of the heating power of the edge heating region 12 in real time, and determines the warping state of the wafer 2 from ΔP(C) / P0(C) and ΔP(E) / P0(E). If |ΔP(C) / P0(C)|>|ΔP(E) / P0(E)|, it is determined that the edges of the wafer 2 are bent toward the back surface, with the central part protruding, i.e., bent downwards. If |ΔP(C) / P0(C)|<ΔP(E) / P0(E)|, it is determined that the edges of the wafer 2 are bent toward the front surface, with the central part concave, i.e., bent upwards.

[0087] The change in wafer warp, ΔBOW, is calculated from the correspondences ΔP(C) / P0(C)=f1'(ΔBOW) and ΔP(E) / P0(E)=f2'(ΔBOW). When ΔBOW exceeds a preset threshold, a reminder signal is triggered and sent to the controller.

[0088] In some embodiments, after receiving a reminder signal, the controller activates a film deposition process condition adjustment program. When executing the film deposition process condition adjustment program, it acquires a mapping relationship between the change in wafer warpage ΔBOW and the process conditions. Based on this mapping relationship, it determines the process conditions to be changed and processes the wafer 2 using the changed process conditions, thereby controlling the warpage of the wafer 2 to within the target warpage range.

[0089] Alternatively, the heating tray 1 is equipped with an electrostatic chuck, and the process conditions in step S220 include the voltage of the electrostatic chuck. Furthermore, this method further includes a step of improving the warpage of the wafer by changing the voltage of the electrostatic chuck according to the amount of warpage change ΔBOW of the wafer.

[0090] For example, by increasing the voltage of the electrostatic chuck, the suction force of the heating tray 1 to the wafer 2 can be increased, thereby improving the warping state of the wafer 2 on the heating tray 1.

[0091] Based on the above, the warping state of wafer 2 in the chamber is monitored in real time during the thin film deposition process. When the change in wafer warping ΔBOW exceeds a preset threshold, the film deposition process condition adjustment program is automatically activated to change the warping state of wafer 2, thereby avoiding deterioration of film quality and arcing problems due to wafer warping. Since warping is more likely to occur with increasing film thickness, employing a method to monitor the warping of wafer 2 in real time is particularly significant for films with high thin-film stress and high thickness. Compared to Embodiment 1, the technical considerations of Embodiment 2 not only obtain the wafer warping and its change, but also improve the wafer warping by adjusting the process conditions based on these results.

[0092] Embodiment 3 This embodiment provides a device for monitoring the warpage of a wafer 2 in real time, corresponding to the method for monitoring the warpage of a wafer 2 in real time according to Embodiment 2. The device for monitoring the warpage of a wafer 2 comprises a memory, a monitor, a controller, and an operator.

[0093] The memory is configured to store at least one mapping relationship, which is a mapping relationship between the amount of change in wafer warpage ΔBOW and process conditions.

[0094] For example, a device for monitoring the warpage of wafer 2 in real time is used in a thin-film deposition process, and the process conditions include one or more combinations of the following: gas flow rate, radio frequency power (RF power), chamber pressure (Pressure), gas distribution ratio, terminal matching parameters, and distance (Spacing) between the gas supply assembly 3 and wafer 2.

[0095] The thin film deposition process is carried out by a thin film deposition apparatus. The thin film deposition apparatus comprises a chamber for depositing the thin film, a gas supply assembly 3 for supplying process gas into the chamber, a heating tray 1 positioned below the gas supply assembly 3 for heating the wafer 2, and a radio frequency source that supplies radio frequency power to excite the process gas inside the chamber and dissociate it into plasma gas. The plasma gas then deposits a thin film on the wafer 2.

[0096] For example, the mapping relationship includes a first correspondence and a second correspondence, and the memory is configured to further store the first correspondence and the second correspondence.

[0097] The first correspondence is the relationship between the change in wafer warpage ΔBOW and the thin-film stress, and the second correspondence is the relationship between the thin-film stress and the process conditions.

[0098] The monitor is configured to monitor the change in wafer warp, ΔBOW.

[0099] Exemplary, the monitor is configured to monitor the rate of change ΔP / P0 of the heating power in each heating region of the heating tray, and to determine the corresponding change in wafer warpage ΔBOW based on the rate of change ΔP / P0 of the heating power in each region, where ΔP is the change in the heating power of the heating region, and P0 is the heating power of the heating region in the initial state. The heating tray has at least two heating regions, each heating region is in a set constant temperature control state, wafers are placed in at least two heating regions, and the wafers have wafer regions corresponding to each heating region.

[0100] The controller is configured to receive information from the monitor, which includes the change in wafer warpage ΔBOW. Subsequently, the film deposition process condition adjustment program is activated, and the process conditions to be changed are determined based on the corresponding mapping relationships.

[0101] For example, the monitor is connected to the controller via electrical signals. Multiple mapping relationships are involved, and the controller determines which mapping relationship to use from among the multiple mapping relationships, thereby determining the process conditions that should be changed according to the mapping relationship.

[0102] The operator is configured to receive modified process conditions from the controller and process wafer 2 using those modified conditions.

[0103] For example, the operator is connected to the controller via electrical signals. Upon receiving the changed process conditions, the operator inputs the corresponding process conditions into the thin-film deposition apparatus. By adjusting the process conditions, the thin-film stress is changed, and consequently, the warping of wafer 2 is changed.

[0104] From the above, in the thin film deposition process, the warping status of wafer 2 is monitored in real time. When the change in wafer warping amount ΔBOW exceeds a preset threshold, a pre-set film deposition process condition adjustment program is activated, the corresponding mapping relationship is called, and the film deposition process conditions are calculated and changed. This changes the subsequent thin film stress, controls the warping of wafer 2, and can even be used to restore the warped wafer 2 to a flat state by utilizing the opposite thin film stress.

[0105] While the basic concepts have been explained above, it is clear that for those skilled in the art, the above disclosure of the invention is merely an example and does not constitute a limitation of this application. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and alterations to this application. Since such modifications, improvements, and alterations are proposed in this application, such modifications, improvements, and alterations still fall within the spirit and scope of the exemplary embodiments of this application.

[0106] At the same time, the present application uses specific terminology to describe embodiments of the present application. For example, “one embodiment,” “one embodiment,” and / or “several embodiments” mean features, structures, or characteristics relating to at least one embodiment of the present application. Therefore, it should be emphasized and noted that “one embodiment,” “one embodiment,” “alternative embodiment,” or “exemplary embodiment,” when mentioned more than once in different places in this specification, do not necessarily mean the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the present application may be combined as appropriate.

[0107] Similarly, it should be noted that, in order to simplify the expression of the disclosure and thereby aid in understanding one or more embodiments of the invention, multiple features may be combined into a single embodiment, drawing, or description in the descriptions of the embodiments of the application described herein. However, this method of disclosure does not mean that there are more features required for the subject matter of the application than the features described in the claims. In fact, the features of an embodiment are fewer than the features of each individual embodiment disclosed above combined.

Claims

1. A real-time monitoring method for wafer warpage, In the process of depositing a thin film on a wafer, the rate of change of heating power ΔP / P in each heating region of the heating tray ０ This is monitored in real time, where ΔP is the change in heating power of the heating region, and P ０ This is the heating power of the heating region in its initial state, wherein the heating tray includes at least two heating regions, each heating region is in a set constant temperature control state, a wafer is placed in the at least two heating regions, and the wafer has a wafer region corresponding to each of the heating regions. The rate of change of the heating power ΔP / P ０ A real-time monitoring method for wafer warping, characterized by determining whether a corresponding wafer region has detached from the heating tray based on the above.

2. A real-time monitoring method for wafer warpage according to claim 1, The rate of change of the heating power ΔP / P ０ In the step of determining whether the corresponding wafer region has detached from the heating tray based on the rate of change of the heating power ΔP / P ０ A real-time monitoring method for wafer warpage, characterized in that when the value is < 0, the wafer region corresponding to the corresponding heating region is separated from the heating tray.

3. A real-time monitoring method for wafer warpage according to claim 1, At least two of the heating regions comprise a central heating region and an edge heating region, the edge heating region being located on the outer periphery of the central heating region. The rate of change of the heating power ΔP / P ０ In the step of determining whether the corresponding wafer region has detached from the heating tray based on the above, |ΔP(C) / P ０ (C)|>|ΔP(E) / P ０ (E)|, if so, it is determined that the edge of the wafer bends toward its back surface and the central portion protrudes, |ΔP(C) / P ０ (C)|<|ΔP(E) / P ０ (E)|, if so, it is determined that the edge of the wafer bends toward its front surface and the central portion is recessed. Here, ΔP(C) is the change amount of the heating power corresponding to the central heating region, ΔP(E) is the change amount of the heating power corresponding to the edge heating region, and P ０ (C) is the heating power corresponding to the central heating region in the initial state, and P ０ (E) is the heating power corresponding to the edge heating region in the initial state. A method for real-time monitoring of wafer warpage, characterized by this.

4. A real-time monitoring method for wafer warpage according to claim 3, Furthermore, the rate of change of the heating power ΔP / P ０ The correspondence between the change in wafer warpage ΔBOW is obtained, and based on the correspondence, the current rate of change of heating power ΔP / P ０ A real-time wafer warpage monitoring method characterized by acquiring the amount of change ΔBOW of wafer warpage corresponding to the wafer warpage, and when the amount of change ΔBOW of wafer warpage exceeds a preset threshold, a reminder signal is triggered and sent to a controller.

5. A real-time monitoring method for wafer warpage according to claim 4, The aforementioned correspondence is ΔP(C) / P ０ (C) = f1'(ΔBOW), and ΔP(E) / P ０ (E) = f2'(ΔBOW), where f1' is ΔP(C) / P ０ This shows the relationship between (C) and ΔBOW, where f2' is ΔP(E) / P ０ A real-time monitoring method for wafer warpage, characterized by representing the relationship between (E) and ΔBOW.

6. A real-time monitoring method for wafer warpage according to claim 1, The process of depositing a thin film on the wafer includes a deposition process by PECVD, and the rate of change of heating power ΔP / P for each heating region in the heating tray ０ A real-time monitoring method for wafer warpage, further comprising determining that the thermal effects of the plasma field, chemical reaction, flow field, and heat field on the heating tray are stable, prior to the step of monitoring the warpage in real time.

7. A real-time monitoring method for wafer warpage according to claim 1, The process of depositing a thin film on the wafer includes a CVD deposition process, and the rate of change of heating power ΔP / P for each heating region in the heating tray ０ A real-time monitoring method for wafer warpage, further comprising determining that the chemical reaction, flow field, and thermal effects of the heat field on the heating tray are in a stable state, prior to the step of monitoring the warpage in real time.

8. A real-time monitoring method for wafer warpage according to claim 4, A real-time wafer warpage monitoring method characterized in that, after the controller receives the reminder signal, it determines the process conditions to be changed based on the mapping relationship between the amount of change in wafer warpage ΔBOW and the process conditions, and processes the wafer based on the changed process conditions so that the wafer warpage is controlled to stay within the target warpage range.

9. A real-time monitoring method for wafer warpage, In the process of depositing a thin film on a wafer, the change in wafer warpage ΔBOW is monitored in real time. A real-time wafer warpage monitoring method characterized in that, when the amount of change in wafer warpage ΔBOW exceeds a preset threshold, the process conditions to be changed are determined based on the mapping relationship between the amount of change in wafer warpage ΔBOW and the process conditions, and the wafer is processed using the changed process conditions so that the wafer warpage is controlled to stay within a target warpage range.

10. A real-time monitoring method for wafer warpage according to claim 9, The mapping relationship comprises a first correspondence relationship and a second correspondence relationship, A real-time monitoring method for wafer warpage, characterized in that the first correspondence includes the relationship between the amount of change in wafer warpage ΔBOW and the thin-film stress, and the second correspondence includes the relationship between the thin-film stress and the process conditions.

11. A real-time monitoring method for wafer warpage according to claim 9, In the step of monitoring the change in wafer warpage ΔBOW in real time, the rate of change in heating power ΔP / P for each heating region in the heating tray is used. ０ The rate of change ΔP / P of the heating power is monitored in real time. ０ The change in wafer warpage ΔBOW is monitored in real time accordingly, where the heating tray includes at least two heating regions, each heating region is in a set constant temperature control state, a wafer is placed in the at least two heating regions, the wafer has wafer regions corresponding to each heating region, ΔP is the change in heating power of the heating region, and P ０ A real-time monitoring method for wafer warpage, characterized in that is the heating power of the heating region in its initial state.

12. A real-time monitoring method for wafer warpage according to claim 11, The at least two heating regions comprise a central heating region and an edge heating region, the edge heating region being provided on the outer periphery of the central heating region. In the step of monitoring the change in wafer warpage ΔBOW in real time, |ΔP(C) / P ０ (C) |>|ΔP(E) / P ０ (E) If this is the case, it is determined that the edge of the wafer is curved toward its back surface and the central part is protruding, and |ΔP(C) / P ０ (C) |<|ΔP(E) / P ０ (E)| If this is the case, it is determined that the edge of the wafer is curved toward its front and the central part is concave, and here ΔP(C) / P ０ (C) is the rate of change of heating power corresponding to the central heating region, and ΔP(E) / P ０ (E) is the rate of change of heating power corresponding to the edge heating region, and P ０ (C) is the heating power corresponding to the central heating region in the initial state, and P ０ A real-time monitoring method for wafer warpage, characterized in that (E) is the heating power corresponding to the edge heating region in the initial state.

13. A real-time monitoring method for wafer warpage according to claim 12, Furthermore, the rate of change of the heating power ΔP / P ０ The correspondence between the change in wafer warpage ΔBOW is obtained, and based on the correspondence, the current rate of change of heating power ΔP / P ０ A real-time wafer warpage monitoring method characterized by acquiring the amount of change ΔBOW of wafer warpage corresponding to the wafer warpage, and when the amount of change ΔBOW of wafer warpage exceeds a preset threshold, a reminder signal is triggered and sent to a controller.

14. A real-time monitoring method for wafer warpage according to claim 13, The aforementioned correspondence is ΔP(C) / P ０ (C) = f1'(ΔBOW), and ΔP(E) / P ０ (E) = f2' (ΔBOW), where f1' is ΔP(C) / P ０ This shows the relationship between (C) and ΔBOW, where f2' is ΔP(E) / P ０ A real-time monitoring method for wafer warpage, characterized by representing the relationship between (E) and ΔBOW.

15. A real-time monitoring method for wafer warpage according to claim 9, A real-time monitoring method for wafer warpage, characterized in that the process conditions include one or a combination of gas flow rate, radio frequency power, chamber pressure, gas composition ratio, terminal matching parameters, and deposition thin film time.

16. A real-time monitoring method for wafer warpage according to claim 11, A real-time monitoring method for wafer warpage, characterized in that the heating tray is positioned below the gas supply assembly, the gas supply assembly is for supplying process gas deposited on the wafer surface, and the process conditions include the distance between the gas supply assembly and the wafer.

17. A real-time monitoring method for wafer warpage according to claim 9, A real-time monitoring method for wafer warpage, further comprising the steps of acquiring the wafer warpage BOW value in real time and acquiring the wafer warpage ΔBOW based on the wafer warpage BOW value, prior to the step of monitoring the change in wafer warpage ΔBOW in real time.

18. A real-time monitoring method for wafer warpage according to claim 17, A real-time monitoring method for wafer warpage, characterized in that, in the process of depositing a thin film on a wafer, a first film layer and a second film layer are deposited alternately to form a laminated structure, the first film layer has tensile stress, and the second film layer has compressive stress, and further, in order to control the wafer warpage within a target warpage range, the average thickness of the subsequent second film layer is increased or the average thickness of the subsequent first film layer is decreased when the wafer warpage BOW value is positive, and the average thickness of the subsequent first film layer is increased or the average thickness of the subsequent second film layer is decreased when the wafer warpage BOW value is negative.

19. A real-time monitoring method for wafer warpage according to claim 18, The first film layer is a SiN film layer, and the second film layer is SiO ２ A real-time monitoring method for wafer warpage, characterized by being a thin film layer.

20. A real-time monitoring method for wafer warpage according to claim 10, A real-time method for monitoring wafer warpage, characterized in that the amount of change in wafer warpage ΔBOW is positively correlated with the absolute value of the thin-film stress.

21. A real-time monitoring method for wafer warpage according to claim 10, A real-time monitoring method for wafer warpage, characterized in that the process conditions include the deposition thin film time, and the thin film stress is positively correlated with the deposition thin film time.

22. A real-time monitoring method for wafer warpage according to claim 11, A real-time monitoring method for wafer warpage, characterized in that the heating tray is equipped with an electrostatic chuck, the process conditions include the voltage of the electrostatic chuck, and further, the voltage of the electrostatic chuck is adjusted according to the amount of change ΔBOW of the wafer warpage.

23. A real-time monitoring device for wafer warpage, A memory configured to store at least one mapping relationship, which is a mapping relationship between the amount of change in wafer warpage ΔBOW and process conditions, A monitor configured to monitor the amount of change in the warpage ΔBOW of the wafer in real time, A controller is configured to receive the change in wafer warpage ΔBOW, and when the change in wafer warpage ΔBOW exceeds a preset threshold, to determine the process conditions to be changed based on the mapping relationship between the change in wafer warpage ΔBOW and the process conditions. A real-time wafer warpage monitoring device comprising: an operator configured to receive modified process conditions and process the wafer under the modified process conditions.

24. A real-time monitoring device for wafer warpage according to claim 23, The mapping relationship comprises a first correspondence relationship and a second correspondence relationship, A real-time monitoring device for wafer warpage, characterized in that the first correspondence includes the relationship between the change in wafer warpage ΔBOW and the thin-film stress, and the second correspondence includes the relationship between the thin-film stress and the process conditions.

25. A real-time monitoring device for wafer warpage according to claim 23, The monitor displays the rate of change ΔP / P of the heating power in each heating region of the heating tray. ０ The rate of change ΔP / P of the heating power in each region is monitored. ０ Based on this, the system is configured to determine the corresponding change in the warpage of the wafer, ΔBOW, where ΔP is the change in the heating power of the heating region, and P ０ A real-time monitoring device for wafer warpage, wherein is the heating power of the heating region in the initial state, the heating tray has at least two heating regions, each heating region is in a set constant temperature control state, a wafer is placed in the at least two heating regions, and the wafer has wafer regions corresponding to each of the heating regions.

Images