A wafer slip risk assessment method and chemical mechanical polishing device

Abstract

The present invention provides a wafer slip risk assessment method and a chemical mechanical polishing device, including: S100, collecting the friction torques of the air film and the retaining ring, which are recorded as torqueA and torqueB respectively; the average friction force f of the retaining ring RR Assign a value so that the total friction torque is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s ; Average friction force on air film f w Assign values ​​so that the total friction torque is equal to torqueA, according to f w Calculate the lateral friction force F on the wafer W and friction coefficient μ k ; Define boundary conditions a and b, let a=μ s ‑μ k , b=F RR ‑F W If a<‑0.5 and / or b<‑1500, the wafer is at risk of slipping. The slip evaluation method provided by the present invention can determine the difference between the current working condition and other working conditions according to the size of the lateral friction force and the friction coefficient, and can reproduce the on-site working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer production, and in particular, relates to a wafer slip risk assessment method and a chemical mechanical polishing device. Background Art

[0002] The integrated circuit industry is the core of the information technology industry and plays a key role in promoting the transformation and upgrading of the manufacturing industry towards digitalization and intelligence. Chips are the carriers of integrated circuits. Chip manufacturing involves chip design, wafer manufacturing, wafer processing, electrical measurement, cutting packaging and testing. Among them, chemical mechanical polishing belongs to the wafer manufacturing process. Chemical mechanical polishing (CMP) is an ultra-precision surface processing technology for global flattening.

[0003] The chemical mechanical polishing process includes: sucking the wafer onto the bottom surface of the polishing head, pressing the side of the wafer with the deposition layer against the upper surface of the polishing pad, and the polishing head rotates in the same direction as the polishing pad driven by the driving component and applies a downward load to the wafer; at the same time, the polishing liquid is supplied to the upper surface of the polishing pad and distributed between the wafer and the polishing pad, so that the wafer completes the chemical mechanical polishing of the wafer under the combined action of chemistry and mechanics.

[0004] During the chemical mechanical polishing process, the chemical mechanical polishing equipment may malfunction and the wafer may often separate from the polishing head, i.e., wafer slipout. Under the action of centrifugal force, the wafer after the slip often collides with the machine and breaks, which to a certain extent affects the normal operation of the machine and increases the cost of wafer manufacturing. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a wafer slip risk assessment method and a chemical mechanical polishing device.

[0006] In a first aspect, an embodiment of the present invention provides a method for assessing wafer slip risk, comprising:

[0007] S100, collecting the friction torque of the air film and the retaining ring, which are recorded as torqueA and torqueB respectively;

[0008] S200, average friction force on retaining ring f RR Assign a value so that the total friction torque is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s ;

[0009] S300, average friction force on air film f w Assign values ​​so that the total friction torque is equal to torqueA, according to fw Calculate the lateral friction force F on the wafer W and friction coefficient μ k ;

[0010] S400, define boundary conditions a and b, let a=μ s -μ k , b=F RR -F W If a<-0.5 and / or b<-1500, there is a risk of wafer slippage.

[0011] In some embodiments, step S200 includes:

[0012] S210, the average friction force on the retaining ring is recorded as f RR , derive the combined friction force component and total friction torque Sum on the retaining ring all (M RR );

[0013] S220, f RR Assign a value so that Sum all (M RR ) is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s .

[0014] In some embodiments, step S210 includes:

[0015] S211, with the center of the polishing head as the center, draw circles with r=1, 2, 3..., n-1, n as the radius, and obtain n concentric rings; take a point of angle θ1 on any ring as the origin O' to construct the X1O'Y coordinate system, then the coordinates of a point on the ring can be expressed as (x h ,y h ), x h and h The following formulas are used for calculation:

[0016]

[0017]

[0018] S212, construct an XOY coordinate system with the center of the polishing pad as the origin O, and the straight-line distance and angle of the polishing head on the polishing pad are R h and θ h , R h and θ h The following formulas are used for calculation:

[0019]

[0020] If y h <0, then If y h ≥0, then

[0021] S213, the speed of the polishing head is recorded as m, and the speed of the polishing head (x h ,y h The linear velocity components of the points are v hx and v hy , v hx and v hy The following formulas are used for calculation:

[0022]

[0023]

[0024] The speed of the polishing pad is denoted as q, and the speed of the polishing pad (x p ,y p The linear velocity components of the points are v px and v py , v px and v py The following formulas are used for calculation:

[0025]

[0026]

[0027] S214, polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p The linear velocity components of the points are v gx and v ry , v rx and v ry The following formulas are used for calculation:

[0028] v rx =v hx -v px ;

[0029] v ry =v hx -v px ;

[0030] Polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p ) is v g , v gThe calculation is done using the following formula:

[0031]

[0032] Polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p ) is θ hg , if v gy <0, then If v gy ≥0, then

[0033] S215, the average friction force on the retaining ring is recorded as f RR , then the polishing head (x h ,y h The frictional force components at point ) are f R ' Rx and f R ' Ry , f R ' Rx and f R ' Ry The following formulas are used for calculation:

[0034]

[0035]

[0036] The average friction force on the polishing head is and and The following formulas are used for calculation:

[0037]

[0038]

[0039] The frictional forces acting on the polishing head are Sum(f RRx ) and Sum(f RRy ), Sum(f RRx ) and Sum(f RRy ) are calculated using the following formula:

[0040]

[0041]

[0042] S216, the eccentricity between the polishing head and the polishing pad is constant e, and the (x h ,y hThe friction torque at point ) is denoted as M RR , M RR The calculation is done using the following formula:

[0043]

[0044] The average friction torque on the polishing head is recorded as The calculation is done using the following formula:

[0045]

[0046] The total friction torque on the polishing head is recorded as Sum all (M RR ), Sum all (M RR ) is calculated using the following formula:

[0047]

[0048] In some embodiments, step S220 includes:

[0049] S221, average friction force on retaining ring f RR Assign a value so that the total friction torque Sum all (M RR ) is equal to torqueB;

[0050] S222, according to f RR The value of Sum(f RRx ) and Sum(f RRy ), where Sum(f RRy )≈0, the lateral force F acting on the retaining ring RR ≈Sum(f RRx );

[0051] S223, the friction coefficient between the retaining ring and the polishing pad is denoted as μ s , μ s The calculation is done using the following formula:

[0052]

[0053] Where m is the diameter of the retaining ring and n is the wafer diameter;

[0054] F RR ack =F rr ×S RR ×k;

[0055] Among them, F rr is the pressure of the retaining ring set when collecting torqueB, S RR To maintain the actual area of ​​the ring, k is a constant and is taken as 6895.

[0056] In some embodiments, step S300 includes:

[0057] S310, the average friction force on the wafer is recorded as f w , derive the combined friction force component and total friction torque Sum on the wafer all (M w );

[0058] S320, f w Assign a value so that Sum all (M w ) is equal to torqueA, according to f w Calculate the lateral friction force F on the wafer W and friction coefficient μ k .

[0059] In some embodiments, step S310 includes:

[0060] S311, the average friction force on the wafer is recorded as f w The frictional forces acting on the wafer are f w ' x and f w ' y , f w ' x and f w ' y The following formulas are used for calculation:

[0061]

[0062]

[0063] S312, the average friction force components on the wafer are and and The following formulas are used for calculation:

[0064]

[0065]

[0066] S313, the total friction force components on the wafer are Sum(f wx ) and Sum(f wy ), Sum(f wx ) and Sum(f wy ) are calculated using the following formula:

[0067]

[0068]

[0069] S314, the average friction torque on the wafer is The calculation is done using the following formula:

[0070]

[0071] S315, the total friction torque on the wafer is Sum all (M w ), Sum all (M w ) is calculated using the following formula:

[0072]

[0073] In some embodiments, step S320 includes:

[0074] S321, average friction force on air film f w Assign a value so that the total friction torque Sum all (M w ) is equal to torqueA;

[0075] S322, according to f w The value of Sum(f wx ) and Sum(f wy ), where Sum(f wy )≈0, the lateral force F acting on the wafer W ≈Sum(f wx );

[0076] S323, the friction coefficient between the wafer and the polishing pad is μ k , μ k The calculation is done using the following formula:

[0077]

[0078]

[0079] Among them, F w is the pressure of the air film set when collecting torqueA, c is the diameter of the air film, and k is a constant, which is 6895.

[0080] In a second aspect, another embodiment of the present invention provides a chemical mechanical polishing device, comprising:

[0081] a polishing pad, the surface of which is covered with a polishing pad for polishing a wafer;

[0082] A polishing head is provided with an air film and a retaining ring; wherein the air film is used to press the wafer onto the polishing pad; and the retaining ring is arranged around the periphery of the wafer to limit the position of the wafer;

[0083] A collection module, used to obtain the friction torque of the air film and the retaining ring;

[0084] A control device is used to implement the evaluation method as provided in an embodiment.

[0085] In the third aspect, another embodiment of the present invention provides a device for controlling wafer slip risk, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the evaluation method provided in one embodiment when executing the computer program.

[0086] In a fourth aspect, another embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the evaluation method provided in one embodiment are implemented.

[0087] The beneficial effects of the embodiments of the present invention include:

[0088] The slide evaluation method provided by the present invention can judge the difference between the current working condition and other working conditions according to the size of the lateral friction force and the friction coefficient, can reproduce the on-site working conditions, and evaluate the level of wafer slide risk according to the difference between the two lateral friction forces and the difference in the friction coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The advantages of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings, which are only schematic and do not limit the scope of protection of the present invention, wherein:

[0090] Figure 1 is a flow chart of a method for estimating slide risk provided by an embodiment of the present invention;

[0091] Figure 2 is a coordinate system construction diagram of a chemical mechanical polishing process provided by an embodiment of the present invention;

[0092] Figure 3 It is a schematic structural diagram of a chemical mechanical polishing device provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0093] The technical scheme of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments recorded herein.

[0094] The drawings of this specification are schematic diagrams, which assist in explaining the concept of the present invention and schematically show the shapes of the various parts and their mutual relationships. It should be understood that in order to clearly show the structures of the various components of the embodiments of the present invention, the drawings are not drawn according to the same scale, and the same reference numerals are used to represent the same parts in the drawings. The technical solution of the present invention is further described below through specific implementation methods.

[0095] In the present invention, wafer (Wafer, W) is also called substrate (Substrate), and its meaning and actual function are equivalent.

[0096] Figure 1 The illustrated embodiment provides a method for assessing the risk of wafer W slippage, comprising:

[0097] S100, collecting the friction torque of the air film and the retaining ring, which are recorded as torqueA and torqueB respectively;

[0098] S200, average friction force on retaining ring f RR Assign a value so that the total friction torque is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s ;

[0099] S300, average friction force on air film f w Assign values ​​so that the total friction torque is equal to torqueA, according to f w Calculate the lateral friction force F on wafer w W and friction coefficient μ k ;

[0100] S400, define boundary conditions a and b, let a=μ s -μ k , b=F RR -F W If a<-0.5 and / or b<-1500, there is a risk of wafer w slipping.

[0101] Specifically, the wafer W slip risk assessment method provided in this embodiment includes the following steps:

[0102] (1) Under the same set pressure, the friction torques of the air film and the retaining ring are collected and recorded as torqueA and torqueB respectively;

[0103] like Figure 2 As shown, with the center of the polishing head 100 as the center, circles are drawn with r=1, 2, 3..., n-1, n as radii, respectively, to obtain n concentric rings; a point of angle θ1 on any ring is taken as the origin O' to construct an X1O'Y coordinate system, then the coordinates of a point on the ring can be expressed as (x h ,y h ), x h and h The following formulas are used for calculation:

[0104]

[0105]

[0106] (2) An XOY coordinate system is constructed with the center of the polishing pad 200 as the origin O. The linear distance and angle of the polishing head 100 on the polishing pad 200 are R h and θ h , R h and θ h The following formulas are used for calculation:

[0107]

[0108] If y h <0, then

[0109] If y h ≥0, then

[0110] (3) The speed of the polishing head 100 is denoted as m, and the speed of the polishing head 100 (x h ,y h The linear velocity components of the points are v hx and v hy , v hx and v hy The following formulas are used for calculation:

[0111]

[0112]

[0113] The rotation speed of the polishing pad 200 is denoted as q. p ,yp The linear velocity components of the points are v px and v py , v px and v py The following formulas are used for calculation:

[0114]

[0115]

[0116] (4) (x) on the polishing head 100 h ,y h ) point relative to the (x p ,y p The linear velocity components of the points are v gx and v gy , v gx and v gy The following formulas are used for calculation:

[0117] v gx =v hx -v px Formula (4.1);

[0118] v ry =v hx -v px Formula (4.2);

[0119] Polishing head 100 (x h ,y h ) point relative to the (x p ,y p ) is v g , v g The calculation is done using the following formula:

[0120]

[0121] Polishing head 100 (x h ,y h ) point relative to the (x p ,y p ) is θ hg , if v gy <0, then If v gy <0, then

[0122] (5) The average friction force on the retaining ring is denoted as f RR , then the polishing head 100 (x h ,y hThe frictional force components at point ) are f R ' Rx and f R ' Ry , f R ' Rx and f R ' Ry The following formulas are used for calculation:

[0123]

[0124]

[0125] The average friction force component of the polishing head 100 is and and The following formulas are used for calculation:

[0126]

[0127]

[0128] The frictional forces acting on the polishing head 100 are Sum(f RRx ) and Sum(f RRy ), Sum(f RRx ) and Sum(f RRy ) are calculated using the following formula:

[0129]

[0130]

[0131] (6) The eccentricity between the polishing head 100 and the polishing pad 200 is constant e, and the (x h ,y h The friction torque at point ) is denoted as M RR , m RR The calculation is done using the following formula:

[0132]

[0133] The average friction torque of the polishing head 100 is recorded as The calculation is done using the following formula:

[0134]

[0135] The total friction torque on the polishing head 100 is denoted as Sum all (M RR ), Sum all (M RR ) is calculated using the following formula:

[0136]

[0137] (7) Based on equations (5.1)-(6.3), we can deduce f RR With Sum all (M RR ) between the average friction force f on the retaining ring RR Assign values ​​so that the total friction torque Sum all (M RR ) is equal to torqueB;

[0138] f RR Substitute the assigned values ​​into equation (5.1) and equation (5.2) to obtain f′ RRx and f′ RRy The specific value of

[0139] f′ RRx and f′ RRy Substituting the specific values ​​of into equation (5.3) and equation (5.4) respectively, we can obtain and The specific value of

[0140] Will and Substitute the specific values ​​of into equation (5.5) and equation (5.6) to obtain Sum(f RRx ) and Sum(f RRy )’s specific value;

[0141] Among them, Sum(f RRy )=0; lateral force F on the retaining ring RR ≈Sum(f RRx ) Formula (7.1);

[0142] (8) The friction coefficient between the retaining ring and the polishing pad 200 is denoted by μ s , μ s The calculation is done using the following formula:

[0143]

[0144] Where m is the diameter of the retaining ring and n is the diameter of the wafer W;

[0145] F RR ack =F rg ×S RR ×k Formula (8.2);

[0146] Among them, F rr is the pressure of the retaining ring set when collecting torqueB, S RR To maintain the actual area of ​​the ring, k is a constant and is taken as 6895;

[0147] (9) The average friction force on wafer W is denoted as f w The frictional forces acting on wafer W are f w ' x and f w ' y , f w ' x and f w ' y The following formulas are used for calculation:

[0148]

[0149]

[0150] The average friction force components on wafer W are and and The following formulas are used for calculation:

[0151]

[0152]

[0153] The total friction force components on wafer W are Sum(f wx ) and Sum(f wy ), Sum(f wx ) and Sum(f wy ) are calculated using the following formula:

[0154]

[0155]

[0156] (10) The average friction torque on wafer W is The calculation is done using the following formula:

[0157]

[0158] The total friction torque on wafer W is Sum all (M w ), Sum all (M w ) is calculated using the following formula:

[0159]

[0160] (11) Based on equations (9.1)-(10.2), we can deduce that w With Sum all (M w) between the average friction force on the air film f w Assign values ​​so that the total friction torque Sum all (M w ) is equal to torqueA;

[0161] f w Substituting the assigned value into equation (9.1) and equation (9.2) we get f′ wx and f′ wy The specific value of

[0162] f′ wx and f′ wy Substituting the specific values ​​of into equation (9.3) and equation (9.4) we can obtain and The specific value of

[0163] Will and Substituting the specific values ​​of into equation (9.5) and equation (9.6) respectively, we can get Sum(f wx ) and Sum(f wy )’s specific value;

[0164] Among them, Sum(f wy )=0; the lateral force F acting on the wafer W W ≈Sum(f wx ) Formula (11.1);

[0165] (12) The friction coefficient between the wafer W and the polishing pad 200 is μ k , μ k The calculation is done using the following formula:

[0166]

[0167]

[0168] Among them, F w is the pressure of the air film set when collecting torqueA, c is the diameter of the air film, and k is a constant, which is 6895.

[0169] (13) According to equation (8.1) and equation (12.1), calculate a = μ s -μ k , according to formula (7.1) and formula (11.1) calculate b = F RR -F W If a<-0.5 and / or b<-1500, it indicates that there is a slip risk for wafer W, and the greater the degree of negative a and b, the higher the slip risk; otherwise, there is no slip risk.

[0170] Figure 3The illustrated embodiment provides a chemical mechanical polishing apparatus, comprising:

[0171] a polishing pad 200 , the surface of which is covered with a polishing pad 200 for polishing a wafer W;

[0172] The polishing head 100 is provided with an air film and a retaining ring; wherein the air film is used to press the wafer W onto the polishing pad 200; the retaining ring is arranged around the periphery of the wafer W to limit the position of the wafer W;

[0173] A collection module, used to obtain the friction torque of the air film and the retaining ring;

[0174] A control device is used to implement the evaluation method provided in the above embodiment.

[0175] like Figure 3 As shown, the main components of the chemical mechanical polishing equipment used in the embodiment of the present invention include: a polishing head 100 for holding a wafer W and driving the wafer W to rotate, a polishing disk covered with a polishing pad 200, a dresser 400 for dressing the polishing pad 200, a liquid supply part 300 for providing a polishing liquid, and a control device.

[0176] During the chemical mechanical polishing process, the polishing head 100 presses the wafer W onto the polishing pad 200 covered by the surface of the polishing disk, and the polishing head 100 performs a rotational motion and a radial reciprocating motion along the polishing disk so that the surface of the wafer W in contact with the polishing pad 200 is gradually polished, while the polishing disk rotates, and the liquid supply unit 300 sprays the polishing liquid onto the surface of the polishing pad 200. Under the chemical action of the polishing liquid, the relative movement of the polishing head 100 and the polishing disk causes the wafer W to rub against the polishing pad 200 for polishing. During polishing, the dresser 400 is used to dress and activate the surface morphology of the polishing pad 200. The dresser 400 can be used to remove foreign particles remaining on the surface of the polishing pad 200, such as abrasive particles in the polishing liquid and waste materials falling off the surface of the wafer W, and can also flatten the surface deformation of the polishing pad 200 caused by grinding.

[0177] The polishing head 100 includes a base, an elastic membrane and a retaining ring, both of which are fixed on the lower surface of the base, and the annular retaining ring is located at the periphery of the elastic membrane and is arranged around the elastic membrane. The elastic membrane is used to absorb the wafer W and apply downward pressure to the wafer W, and the retaining ring is used to keep the wafer W under the elastic membrane to prevent the wafer W from slipping out.

[0178] The embodiment of the present invention also provides a control device for the risk of wafer W sliding, which includes: a processor, a memory, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the following is implemented: Figure 1 The evaluation method steps are shown.

[0179] The control device refers to a terminal with data processing capabilities, including but not limited to computers, workstations, servers, and even some high-performance smart phones, PDAs, tablet computers, personal digital assistants (PDAs), smart TVs, etc. The control device is generally installed with an operating system, including but not limited to: Windows operating system, LINUX operating system, Android operating system, Symbian operating system, Windows mobile operating system, and iOS operating system, etc. The above lists specific examples of the control device in detail, and those skilled in the art can realize that the control device is not limited to the above listed examples.

[0180] The embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following is implemented: Figure 1 The evaluation method steps are shown.

[0181] Among them, the computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, the steps of each of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. Computer-readable media may include: any entity or device capable of carrying computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0182] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0183] Example

[0184] This embodiment provides a method for assessing the risk of wafer W slipping, which specifically includes the following steps:

[0185] (1) Under the same set pressure, the friction torques of the air film and the retaining ring are collected and recorded as torqueA and torqueB respectively;

[0186] A point (x h ,y h ) is used as an example to derive the following points. The derivation process of other points on the ring is the same and will not be repeated here.

[0187] x h and h The following formulas are used for calculation:

[0188]

[0189]

[0190] (2) An XOY coordinate system is constructed with the center of the polishing pad 200 as the origin O. The linear distance and angle of the polishing head 100 on the polishing pad 200 are R h and θ h , R h and θ h The following formulas are used for calculation:

[0191]

[0192]

[0193] (3) The speed of the polishing head 100 is m=90, (x h ,y h The linear velocity components of the points are v hx and v hy , v hx and v hy The following formulas are used for calculation:

[0194]

[0195]

[0196] The rotation speed of the polishing pad 200 is q=93, and the linear velocity components of any point on the polishing pad 200 are v px and v py , v px and v -y The following formulas are used for calculation:

[0197]

[0198]

[0199] (4) (x) on the polishing head 100 h ,y h ) point relative to the (x p ,y pThe linear velocity components of the points are v rx and v ry , v rx and v ry The following formulas are used for calculation:

[0200] v rx =v hx -v -x =-801.106-1119.978=-1921.084(mm / min) Formula (4.1);

[0201] v ry =v hx -v px =1387.557-1433.808=-46.252(mm / min) Formula (4.2);

[0202] Polishing head 100 (x h ,y h ) point relative to the (x p ,y p ) is v r , v r The calculation is done using the following formula:

[0203]

[0204] Polishing head 100 (x h ,y h ) relative to the polishing pad 200 is θ hr ,θ hr The calculation is done using the following formula:

[0205]

[0206] (5) The average friction force on the retaining ring is denoted as f RR , then the polishing head 100 (x h ,y h The frictional force components at point ) are f′ RRx and f′ RRy , f′ RRx and f′ RRy The following formulas are used for calculation:

[0207]

[0208]

[0209] The average friction force component of the polishing head 100 is and and The following formulas are used for calculation:

[0210]

[0211]

[0212] The frictional forces acting on the polishing head 100 are Sum(f RRx ) and Sum(f RRy ), Sum(f RRx ) and Sum(f RRy ) are calculated using the following formula:

[0213]

[0214]

[0215] (6) The eccentric distance between the polishing head 100 and the polishing pad 200 is constant e=200, and the (x h ,y h The friction torque at point ) is denoted as M RR , M RR The calculation is done using the following formula:

[0216]

[0217] The average friction torque of the polishing head 100 is recorded as The calculation is done using the following formula:

[0218]

[0219] The total friction torque on the polishing head 100 is denoted as Sum all (M RR ), Sum all (M RR ) is calculated using the following formula:

[0220]

[0221] (7) Based on equations (5.1)-(6.3), we can deduce f rR With Sum all (M RR ) between the average friction force f of the ring RR The value is assigned as 0.23, and the total friction torque Sum is obtained by stepwise calculation through formulas (5.1)-(6.3) all (M RR ) is 32.015. At this time, Sum all (M RR )≈torqueB=32.04(Nm);

[0222] f RR =0.23 is substituted into equation (5.1) and equation (5.2), and we get:

[0223]

[0224]

[0225] f R ' Rx = 0.230N and f R ' Ry =0.006N Substituting into equation (5.3) and equation (5.4) respectively, we can get:

[0226]

[0227] Will and Substituting into equation (5.5) and equation (5.6) respectively, we can get:

[0228] Sum(f RRx )=896.845(N), Sum(f RRy )=0.005(N);

[0229] Lateral force F on retaining ring RR ≈Sum(f RRx )=896.845(N)Formula (7.1);

[0230] (8) The friction coefficient between the retaining ring and the polishing pad 200 is denoted by μ s , μ s The calculation is done using the following formula:

[0231]

[0232] (9) The average friction force on wafer W is denoted as f w The friction force components on wafer W are f′ wx and f′ wy , f′ wx and f′ wy The following formulas are used for calculation:

[0233]

[0234]

[0235] The average friction force components on wafer W are and and The following formulas are used for calculation:

[0236]

[0237]

[0238] The total friction force components on wafer W are Sum(f wx ) and Sum(f wy ), Sum(f wx ) and Sum(f wy ) are calculated using the following formula:

[0239]

[0240]

[0241] (10) The average friction torque on wafer W is The calculation is done using the following formula:

[0242]

[0243] The total friction torque on wafer W is Sum all (M w ), Sum all (M w ) is calculated using the following formula:

[0244]

[0245] (11) Based on equations (9.1)-(10.2), we can deduce that w With Sum all (M w ) between the average friction force of the air film f w The value is assigned as 0.568N. After step-by-step calculation through equations (9.1)-(10.2), the total friction torque Sum is obtained. all (M w ) is 87.206Nm, Sum all (M w )≈torqueA=87.18Nm;

[0246] f w =0.568N Substituting into equation (9.1) and equation (9.2), we can get:

[0247]

[0248]

[0249] f′ wx = 0.007N and f′ wy=0.001N Substituting into equation (9.3) and equation (9.4) respectively, we can get:

[0250]

[0251] Will and Substituting into equation (9.5) and equation (9.6) respectively, we can obtain:

[0252] Sum(f wx )=6207.189(N), Sum(f wy )=0(N);

[0253] The lateral force F on wafer W W ≈Sum(f wx ) = 6207.189 (N) Formula (11.1);

[0254] (12) The friction coefficient between the wafer W and the polishing pad 200 is μ k , μ k The calculation is done using the following formula:

[0255]

[0256] (13) According to equation (8.1) and equation (12.1), calculate a = μ s -μ k =0.103-0.904=-0.801, according to formula (7.1) and formula (11.1), b=F RR -F W =896.845-6207.189=-5310.345, satisfying a<-0.5, b<-1500, indicating that wafer W has a slip risk.

[0257] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for assessing wafer slip risk, characterized in that: include: S100, collecting the friction torque of the air film and the retaining ring, which are recorded as torqueA and torqueB respectively; S200, average friction force on retaining ring f RR Assign a value so that the total friction torque is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s ; S300, average friction force on air film f w Assign values ​​so that the total friction torque is equal to torqueA, according to f w Calculate the lateral friction force F on the wafer w and friction coefficient μ k ; S400, define boundary conditions a and b, let a=μ s -μ k , b=F RR -F W If a<-0.5 and / or b<-1500, there is a risk of wafer slippage.

2. The evaluation method according to claim 1, characterized in that: Step S200 includes: S210, the average friction force on the retaining ring is recorded as f RR , derive the combined friction force component and total friction torque Sum on the retaining ring all (M RR ); S220, f RR Assign so that Sum all (M RR ) is equal to torqueB, according to f RR Calculate the lateral force F acting on the retaining ring RR and friction coefficient μ s .

3. The evaluation method according to claim 2, characterized in that: Step S210 includes: S211, with the center of the polishing head as the center, draw circles with r=1, 2, 3..., n-1, n as the radius, and obtain n concentric rings; take a point of angle θ1 on any ring as the origin O' to construct the X1O'Y coordinate system, then the coordinates of a point on the ring can be expressed as (x h ,y h ), x h and h The following formulas are used for calculation: S212, construct an XOY coordinate system with the center of the polishing pad as the origin O, and the straight-line distance and angle of the polishing head on the polishing pad are R h and θ h , R h and θ h The following formulas are used for calculation: If y h <0, then If y h ≥0, then S213, the speed of the polishing head is recorded as m, and the speed of the polishing head (x h ,y h The linear velocity components of the points are v hx and v hy , v hx and v hy The following formulas are used for calculation: The speed of the polishing pad is denoted as q, and the speed of the polishing pad (x p ,y p The linear velocity components of the points are v px and v py , v px and v py The following formulas are used for calculation: S214, polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p The linear velocity components of the points are v rx and v ry , v rx and v ry The following formulas are used for calculation: v rx =v hx -v px ; v ry =v hx -v px ; Polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p ) is v r , v r The calculation is done using the following formula: Polishing head (x h ,y h ) point relative to the polishing pad (x p ,y p ) is θ hr , if v ry <0, then If v ry ≥0, then S215, the average friction force on the retaining ring is recorded as f RR , then the polishing head (x h ,y h The frictional force components at point ) are f′ RRx and f′ RRy , f′ RRx and f′ RRy The following formulas are used for calculation: The average friction force on the polishing head is and and The following formulas are used for calculation: The frictional forces acting on the polishing head are Sum(f RRx ) and Sum(f RRy ), Sum(f RRx ) and Sum(f RRy ) are calculated using the following formula: S216, the eccentricity between the polishing head and the polishing pad is constant e, and the (x h ,y h The friction torque at point ) is denoted as M RR , M RR The calculation is done using the following formula: The average friction torque on the polishing head is recorded as The calculation is done using the following formula: The total friction torque on the polishing head is recorded as Sum all (M RR ), Sum all (M RR ) is calculated using the following formula:

4. The evaluation method according to claim 2, characterized in that: Step S220 includes: S221, average friction force on retaining ring f RR Assign a value so that the total friction torque Sum all (M RR ) is equal to torqueB; S222, according to f RR The value of Sum(f RRx ) and Sum(f RRy ), where Sum(f RRy )≈0, the lateral force F acting on the retaining ring RR ≈Sum(f RRx ); S223, the friction coefficient between the retaining ring and the polishing pad is denoted as μ s , μ s The calculation is done using the following formula: Where m is the diameter of the retaining ring and n is the wafer diameter; F RR act =F rr ×S RR ×k; Among them, F rr is the pressure of the retaining ring set when collecting torqueB, S RR To maintain the actual area of ​​the ring, k is a constant and is taken as 6895.

5. The evaluation method according to claim 1, characterized in that: Step S300 includes: S310, the average friction force on the wafer is recorded as f w , derive the combined friction force component and total friction torque Sum on the wafer all (M w ); S320, f w Assign so that Sum all (M w ) is equal to torqueA, according to f w Calculate the lateral friction force F on the wafer W and friction coefficient μ k .

6. The evaluation method according to claim 5, characterized in that: Step S310 includes: S311, the average friction force on the wafer is recorded as f w The friction force components on the wafer are f′ wx and f′ wy , f′ wx and f′ wy The following formulas are used for calculation: S312, the average friction force components on the wafer are and and The following formulas are used for calculation: S313, the total friction force components on the wafer are Sum(f wx ) and Sum(f wy ), Sum(f wx ) and Sum(f wy ) are calculated using the following formula: S314, the average friction torque on the wafer is The calculation is done using the following formula: S315, the total friction torque on the wafer is Sum all (M w ), Sum all (M w ) is calculated using the following formula:

7. The evaluation method according to claim 5, characterized in that: Step S320 includes: S321, average friction force on air film f w Assign a value so that the total friction torque Sum all (M w ) is equal to torqueA; S322, according to f w The value of Sum(f wx ) and Sum(f wy ), where Sum(f wy )≈0, the lateral force F acting on the wafer W ≈Sum(f wx ); S323, the friction coefficient between the wafer and the polishing pad is μ k , μ k The calculation is done using the following formula: Among them, F w is the pressure of the air film set when collecting torqueA, c is the diameter of the air film, and k is a constant, which is 6895.

8. A chemical mechanical polishing device, characterized in that: include: a polishing pad, the surface of which is covered with a polishing pad for polishing a wafer; A polishing head is provided with an air film and a retaining ring; wherein the air film is used to press the wafer onto the polishing pad; and the retaining ring is arranged around the periphery of the wafer to limit the position of the wafer; A collection module, used to obtain the friction torque of the air film and the retaining ring; A control device, used to implement the evaluation method as described in any one of claims 1 to 7.

9. A wafer slip risk control device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the evaluation method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the evaluation method according to any one of claims 1 to 7 are implemented.

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