CN115890472A - Wafer polishing pressure control method, pressure applying device, control device and polishing equipment - Google Patents
Wafer polishing pressure control method, pressure applying device, control device and polishing equipment Download PDFInfo
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Abstract
The invention provides a wafer polishing pressure device, which comprises a shell, N pressing blocks and pressing block fixing elements, wherein the N pressing blocks and the pressing block fixing elements are arranged in the shell and are made of different materials, the shell is a cylindrical groove with an open top end, and a wafer to be processed can be adhered to the bottom end of the cylindrical groove; the N pressing blocks are arranged concentrically and have equal volume; the pressing block fixing element is arranged at the top ends of the pressing block and the shell and is matched with the shell to fixedly install the N pressing blocks in the shell, and N is a natural number larger than or equal to 3. The pressing device realizes gravity stable loading by adopting pressing blocks made of different materials, ensures the stability of polishing pressure in the wafer polishing process, is favorable for improving the surface shape precision of wafer processing, reduces the rejection rate, and has the advantages of simple structure, convenient operation and low cost. The invention also provides a pressure control device and polishing equipment comprising the wafer polishing and pressing device. In addition, the invention also provides a wafer polishing pressure control method.
Description
Technical Field
The invention relates to the technical field of polishing, in particular to a wafer polishing pressure control method, a polishing pressure applying device, a polishing pressure control device and polishing equipment.
Background
With the rise and prosperity of integrated circuits, the semiconductor industry is increasingly strong, the development trend is high, wafers are the foundation stones of semiconductor chips, the processing precision directly determines the service performance and the service life of the chips, therefore, the ultra-precision processing of the wafers is an industry development trend for improving the processing precision. Therefore, the ultra-smooth, ultra-flat and low-damage processing requirements are provided for ultra-precise processing of the wafer, and chemical mechanical polishing is the only method capable of meeting the requirement of wafer processing at present.
According to Preston equation, the removal efficiency of the material is related to the relative velocity v, the polishing pressure P and the Preston coefficient k of the point, and in order to obtain an ultra-flat processed surface, the material removal rate of any point on the surface of the wafer is ensured to be consistent, and under the condition that v and k are constant, the polishing pressure P is the only factor influencing the material removal uniformity. Through extensive research, it has been found that although a uniform load is applied to the wafer upper surface, the stress distribution on the wafer processing surface and the contact surface of the polishing pad is not uniform, and edge effects are generated, resulting in an "over-polishing" phenomenon at the wafer edge, which is caused by an increase in the wafer edge contact stress.
The edge effect that the wafer appears makes the control to wafer angularity and bow doubly show the difficulty, and the leading reason has: 1) The size of the wafer is getting bigger, the diameter of the commercial wafer is 8 inches, and the commercial wafer is gradually moved to 12 inches, but the thickness of the wafer is only about 0.4mm, the wafer is easy to warp and bend due to the overlarge diameter-thickness ratio (the ratio of the diameter to the thickness), even if a uniform load is applied on the surface of the wafer, the wafer is affected by the soft polishing pad, the edge effect is generated due to the uneven distribution of the contact stress of the polished surface of the wafer, and the surface shape precision is deteriorated; 2) In order to control the polishing pressure, mechanical and pneumatic methods are currently used for controlling the polishing pressure. The mechanical method mainly comprises a counterweight method, a spring method and a transmission method, wherein the counterweight method is to add a heavy object block on a wafer and realize pressure loading by gravity; the spring method refers to controlling the magnitude of pressure by means of elastic deformation of a spring; the transmission method mainly determines the magnitude of the applied load by controlling the distance between the wafer and the polishing pad through mechanical transmission, such as lead screw transmission, gear transmission and the like. The pneumatic type mainly controls the polishing pressure by changing the air pressure in the air bag on the surface of the wafer. Among the above control methods, the counterweight method is the simplest and convenient to operate, but partition control cannot be realized; the spring method and the transmission method can not ensure the stability of the applied pressure in the polishing process; although the pneumatic type can realize the regional pressure control by adjusting the distribution of polishing pressure by controlling the pressure of the air bag above different regions, the structure is complex, the air source needs to be added, the cost is high, and the gas dynamics shows that the pressure at the gas inlet is high, so that the stress on the surface of the wafer is not uniform.
Therefore, there is a need in the art for a wafer polishing pressure control device with simple structure, convenient operation and low cost to meet the current processing requirements.
Disclosure of Invention
In view of the above, the present invention is to provide a wafer polishing pressure control method, a polishing pressure applying device, a polishing pressure control device and a polishing apparatus, which have the advantages of being convenient to operate, simple in structure, low in cost, etc. while realizing the zone control of the wafer polishing pressure.
Therefore, the invention designs a wafer polishing pressure applying device, a polishing pressure control method and polishing equipment based on the following principles, and the specific design principle is as follows: when the volumes are the same, the mass is in direct proportion to the density; by utilizing the determinacy of the gravity direction and the gravity size, the pressure load of different polishing areas can be changed by controlling the volume and the density in a weight loading mode, so that the determinacy control of the pressure can be realized.
The specific principle implementation method is as follows: as shown in FIG. 1, the pressing device comprises n pressing blocks, wherein the first pressing block, the second pressing block, the third pressing block, \ 8230, the (n-1) th pressing block and the (n) th pressing block are marked in sequence, and the surface Z of the wafer can be controlled 1 、Z 2 、Z 3 、…、Z n The height of each pressing block is h, and the radius is sequentially recorded as R from inside to outside 1 、R 2 、R 3 、…、R n-1 、R n Density is rho 1 、ρ 1 、ρ 1 、…、ρ n-1 、ρ n 。
Knowing that the volumes of the n compacts are equal, the radii satisfy the following relationship:
r can be obtained by calculation 1 And R n The relationship between them is as follows:
as can be seen from formula (2), when R is n And R 1 When the above relations are satisfied, the volume of each pressing block is the same, and the size of the volume is only the height h and the height R 1 It is relevant. When R is 1 After determination, the volume is changed by adjusting the thickness h.
The mass of the pressing block n is as follows:
when the volume of the compact is equal, the mass and density of the compact are proportional, and the load applied to the wafer is also proportional to the density of the compact.
Accordingly, the present invention provides a pressure applying apparatus for wafer polishing, comprising: the wafer processing device comprises a shell, N pressing blocks made of different materials and a pressing block fixing element, wherein the N pressing blocks and the pressing block fixing element are arranged in the shell, the shell is a cylindrical groove with an open top end, and a wafer to be processed can be stuck to the bottom end of the cylindrical groove; the N pressing blocks are arranged concentrically and have equal volume; the pressing block fixing element is arranged at the top ends of the pressing block and the shell and is matched with the shell to fixedly install the N pressing blocks in the shell, and N is a natural number larger than or equal to 3.
Based on the above, as shown in fig. 1, the N pressing blocks are composed of a columnar pressing block located at the center and N-1 pressing block rings concentrically arranged with the columnar pressing block, and the heights of the columnar pressing block and the pressing block rings are equal; wherein the radius of the columnar pressing block is R 1 Outer ring radius of said pressure block ring
N represents the nth briquetting, and N is more than or equal to 2 and less than or equal to N.
Based on the above, the pressing block fixing element is a fixing plate, and the center of the fixing plate is fixed at the center of the columnar pressing block; therefore, the pressing block is prevented from rotating automatically and floating up and down in the working process of the pressing device.
Based on the above, each pressing block is provided with the blind hole, and the blind holes can be provided with screws so as to facilitate carrying and mounting of the pressing blocks.
Based on the above, be provided with the transport rings on N briquetting to conveniently carry pressure device.
The present invention also provides a wafer polishing pressure control apparatus, comprising: the workpiece shaft component is connected with the clamp through a coupler, the pressing device is clamped in the clamp, the workpiece shaft component carries the pressing device to rotate through the coupler and the clamp, and the polishing shaft component can polish the wafer to be processed in a rotating mode.
Based on the above, the clamp comprises a clamp body, an adjusting plate, a connecting plate and a clamping block, wherein the center of the clamp body is connected with one end of the coupler; the adjusting plate is arranged on the clamp body; the upper end of the connecting plate is arranged on the adjusting plate, and the lower end of the connecting plate is connected with the clamping block; the clamping block carries the connecting plate through the adjusting plate to clamp and fix the pressure applying device, so that the pressure applying device rotates along with the coupler.
Based on the above, an adjusting groove is formed in the middle of the adjusting plate, and the position of the adjusting plate is adjusted through the adjusting groove, so that the clamping block clamps and fixes the pressure applying device.
Based on the above, the clamping blocks are matched with the shell to fix the pressing device in the clamp. Preferably, the contact surface of the clamping block and the shell is a plane or an arc surface.
Based on the above, a plurality of lightening holes are uniformly formed in the fixture body.
The invention provides a wafer polishing pressure control method, which comprises the following steps: 1) Determining wafer size and pressure control sub-zone Z n The radius R of the pressing blocks with equal volumes is obtained by analysis and calculation n Values, wherein N represents the nth compact and N is greater than or equal to 2 and less than or equal to N; 2) Selecting a plurality of materials as materials for preparing a pressing block, setting polishing pressure, and calculating roundness under the condition that the pressure of each subarea is equal to obtain a height value h of the pressing block; 3) Finite element software Ansys is used for simulating and analyzing the influence of different applied loads on the contact stress, the uniform distribution of the contact stress is met as far as possible as standard, and the sub-area Z is determined n Applying a load; 4) According to a determined sub-zone Z n Determining the proper sub-region Z n Density value rho of the pressing block; 5) And manufacturing corresponding pressing blocks according to the determined material and size of the pressing blocks, assembling the pressing devices, and assembling the pressing devices into the workpiece shaft component for controlling the wafer polishing pressure.
The invention provides polishing equipment comprising the wafer polishing pressure control device.
The pressing device provided by the invention is designed into annular or cylindrical entities with equal height and equal volume in different areas, and materials with different densities are selected to obtain the pressing devices with different qualities in different areas; the pressure conditions of different areas of the surface of the wafer are changed according to the gravity of the sub-area pressing block, the contact stress distribution between the wafer and the polishing pad is controlled, on one hand, the influence of the edge effect is reduced, on the other hand, the polishing pressure can be adjusted according to the initial surface shape precision of the wafer, so that the purpose of improving the surface shape precision of the polished wafer is achieved, and the processing requirements of the ultra-smooth and high-flatness of the wafer are met. Therefore, the invention mainly adopts a weight loading mode, utilizes the determinacy of the gravity direction and the gravity size, and changes the pressing loads of different areas by controlling the volume and the density so as to achieve the purpose of controlling the pressure determinacy. Therefore, no matter how the contact state of the wafer and the polishing pad interface changes in the polishing process, the applied load is the gravity of the pressure applying device, the pressure is constant, the deterministic polishing of the wafer is facilitated, and the processing quality is improved. The pressing block used in the pressing device is an annular or cylindrical body, and is simple in structure and convenient to manufacture. The pressing blocks in the pressing device are all made of common metal or alloy materials, the price is low, and compared with a gas pressure device, the pressing device is low in cost.
The wafer polishing pressure control method provided by the invention mainly adopts equal-height and equal-volume pressing blocks, and realizes pressure control by changing the density of the pressing blocks.
The control method provided by the invention is suitable for batch production of wafers, and the applicable pressure device can be obtained by only once calculation and analysis for the wafers with the same size.
The control method provided by the invention is different from a gas pressure device, and the pressure applying device adopted by the invention does not need a gas source, a pipeline and a control system, only needs to be placed on the polishing disk and driven to rotate by the workpiece shaft, and is convenient to operate.
Therefore, the pressing device, the control device and the polishing equipment provided by the invention realize stable gravity loading by adopting pressing blocks made of different materials as regional pressing carriers, ensure the stability of polishing pressure in the wafer polishing process, are beneficial to improving the surface shape precision of wafer processing and reducing the rejection rate, and have the advantages of simple structure, convenience in operation and low cost.
Drawings
FIG. 1 is a layout diagram of a pressing block of the wafer polishing and pressing device provided by the invention.
Fig. 2 is a top view of a wafer polishing and pressing device according to an embodiment of the present invention.
Fig. 3 isbase:Sub>A cross-sectional view ofbase:Sub>A wafer polishing and pressing apparatus according to an embodiment of the present invention, taken along the linebase:Sub>A-base:Sub>A in fig. 2.
Fig. 4 is a schematic structural diagram of a wafer polishing control apparatus according to a second embodiment of the present invention.
Fig. 5 is a front view of a jig used in the second embodiment of the present invention.
Fig. 6 is a top view of the fixture shown in fig. 5.
Fig. 7 is a graph showing the distribution of wafer stress when the pressures of the zones are all 36N by using the control device provided by the third embodiment of the present invention.
FIG. 8 is a graph showing the influence of the pressure F on the contact stress of compacts of different densities by using the control device provided by the third embodiment of the present invention, wherein the pressure F is from the first compact to the fourth compact 1 -F 2 -F 3 -F 4 Respectively 35.6-36-35.6 in figure (a), 33-36-36-33 in figure (b), 36-33-21.9-12.5 in figure (c), 36-36-36-29 in figure (d), 36-35.6-33-29 in figure (e) and 36-35.6-33-21.9 in figure (f).
FIG. 9 is a surface profile of a wafer polished under a mode condition for a verification experiment of polishing experiments according to the present invention.
FIG. 10 is a graph of the polished surface of a wafer under the two conditions of the inventive polishing experiment verification experiment.
Wherein reference symbols in the various figures represent: 1 polishing a shaft; 2, polishing a disc; 3 polishing the pad; 4, a wafer to be processed; 5 a pressing device; 51 a housing; 52, carrying the lifting ring; 53 fixing the plate; 54 a first briquette; 55 second pressing block; 56 a third briquetting; 57 a fourth briquette; 58 blind holes; 6, clamping; 61, a clamp body; 62 an adjustment plate; 63 connecting plates; 64 clamp blocks; 65 an adjustment groove; 66 lightening holes; 7, a coupler; 8 workpiece axle boxes; 9 workpiece axis.
Detailed Description
The technical solution of the present invention is further described in detail by the following embodiments.
Example one
Referring to fig. 2 and 3, a pressure applying device 5 for wafer polishing according to an embodiment of the present invention mainly includes a housing 51, two carrying rings 52, a fixing plate 53, and four pressing blocks concentrically arranged in the housing 51.
The shell 51 is a cylindrical groove with an open top end, and the bottom end of the cylindrical groove can be adhered with the wafer 4 to be processed and can move along with the pressure applying device 5. The carrying slings 52 are screwed to the housing 51 to facilitate carrying of the press. The top ends of the four pressing blocks are provided with grooves matched with the fixing plate 53, so that the fixing plate 53 is just installed in the grooves of the four pressing blocks, and the center of the fixing plate 53 is fixed on the center of the four pressing blocks, thus, the four pressing blocks are fixedly installed in the shell 51 under the action of the fixing plate 53, and the four pressing blocks are prevented from rotating automatically or floating up and down in the working process of the pressing device 5.
The four pressing blocks are respectively a first pressing block 54, a second pressing block 55, a third pressing block 56 and a fourth pressing block 57 which are equal in volume and height, and the four pressing blocks are different in material and density. The first pressing block 54, the second pressing block 55, the third pressing block 56 and the fourth pressing block 57 are provided with grooves matched with the fixing plate 53, so that the fixing plate 53 is convenient to mount, the height of the whole pressing device can be ensured to be consistent, and the whole pressing device is attractive. The first pressing block 54 is a columnar pressing block and is located at the positive center of the four pressing blocks, and the center of the fixing plate 53 is connected to the center of the first pressing block 54 through threads. Second briquetting 55, third briquetting 56 and fourth briquetting 57 are the briquetting ring, are cyclic annular, and the external diameter radius increases in proper order, and the outer loop radius that corresponds satisfies:
n represents the nth briquetting and is respectively 2, 3 and 4. Each pressing block is respectively provided withA blind hole 58, wherein a nut can be arranged in the blind hole 58 so as to be convenient for carrying and installing a corresponding pressing block. In the embodiment, under the equal-volume and equal-height conditions, the pressing blocks are made of different materials, so that the corresponding densities are different, the gravity of the pressing blocks is changed by changing the densities of the pressing blocks, and the pressure can be controlled in different regions.
Each briquetting in the pressing device 5 provided by this embodiment controls the pressure of one sub-area, and the volumes of the four briquettes are all equal, and the weight is controlled by changing the density of the briquettes, so as to realize the pressure control of different areas. The wafer 4 to be processed is adhered below the pressure device 5 and placed on the polishing pad, the wafer 4 to be processed is driven to rotate by the workpiece shaft, and the polishing pad is adhered on the polishing disc and driven to rotate by the polishing shaft. The wafer 4 to be processed removes materials by means of the pressure applied by the pressure applying device 5, the relative movement of the workpiece shaft and the polishing shaft, and the chemical mechanical action of the polishing solution, and due to the difference of the pressure applied on the surface of the wafer 4 to be processed, the material removal rates of different areas can be effectively controlled, so that the deterministic control of the polishing process is met.
Example two
Referring to fig. 4, the present embodiment provides a wafer polishing pressure control apparatus, including: the polishing shaft member, the workpiece shaft member, the pressing device 5 provided in the first embodiment, and the jig 6 for holding and fixing the pressing device 5.
The polishing shaft component comprises a polishing shaft 1, a polishing disc 2 and a polishing pad 3, wherein the polishing disc 2 and the polishing shaft 1 are concentrically fixed together, the polishing pad 3 is adhered to the polishing disc 2, and the polishing disc 2 and the polishing pad 3 rotate along with the polishing shaft 1.
The workpiece shaft members include a workpiece axle box 8 and a workpiece axle 9, and the workpiece axle 9 is mounted in the workpiece axle box 8. The clamp 6 is connected with the workpiece shaft 9 through a coupler 7. The clamp 6 drives the pressing device 5 to realize a rotating function. The wafer 4 to be processed is adhered below the pressing device 5 and is driven to rotate by the workpiece shaft 9 along with the pressing device 5.
Referring to fig. 5 and 6, the body 6 mainly includes a clamp body 61, four adjusting plates 62, four connecting plates 63, and four clamping blocks 64. The fixture body 61 is mainly used for connecting the coupler 7 and the adjusting plate 62, and a plurality of weight-reducing holes 66 are uniformly distributed in the fixture body. The clamp body 61 and the coupler 7 are fastened through screws. The adjusting plates 62 are fixed on the clamp body 61 by screws, and an adjusting groove 65 is formed in the middle of each adjusting plate 62, and the position of the adjusting plate 62 can be adjusted according to the size of the pressing device 5 through the adjusting groove 65. The upper end of the connecting plate 63 is fixed with the adjusting plate 62 through screws, and the lower end of the connecting plate is fixed with the clamping block 64 through screws. Thus, one end of the clamping block 64 is connected with the connecting plate 63, the other end of the clamping block 64 is in contact with the pressing device 5, and the clamping block 64 carries the connecting plate 62 through the adjusting plate 62 to clamp and fix the pressing device 5, so that the pressing device 5 rotates along with the workpiece shaft 9. Wherein the clamping block 64 cooperates with the housing 51 to fix the pressing device 5 in the fixture 6. The contact surface of the clamping block 64 and the shell 51 is a plane, that is, the surface of the clamping block 64 for contacting the shell 51 is a plane, the surface of the shell 51 for contacting the clamping block 64 is also a plane, and four plane cutting surfaces are arranged on the outer side surface of the shell 51 for contacting the clamping block 64, so that the pressing device 5 is firmly fixed in the fixture 6; and transmits the torque of the workpiece shaft 9 through the clamp block 64 to rotate the pressing device 5 following the workpiece shaft 9. In other embodiments, the contact surface of the clamping block 64 and the shell 51 is a cambered surface.
EXAMPLE III
This example provides a wafer polishing pressure control method for polishing 8 inch, 0.4mm thick single crystal silicon. The control method adopts the wafer polishing pressure control device provided by the second embodiment and mainly comprises the following steps:
1) The diameter of the single crystal silicon wafer was determined to be 200mm and divided into 4 divisional regions, and R was found to be 4 =100mm, calculated by the formula (2), R 1 ＝50mm，R 2 ＝70.7mm，R 3 ＝86.6mm。
2) Selecting a common density of 7800kg/m 3 Cast carbon steel of 7700kg/m density 3 Cast stainless steel of (2), density 7200kg/m 3 Gray cast iron of 6300kg/m density 3 Zinc aluminum complex ofGold, density 4730kg/m 3 Titanium alloy of (2) having a density of 2700kg/m 3 Aluminum material, etc. as a briquette material; in this example, the polishing pressure was set to 5kPa, and the height h of each compact was determined by calculation and rounding to be 60mm in combination with the equations (3) and (4).
3) Simulation analysis is performed by adopting Ansys software, the material of each of the four compacts is selected primarily as cast carbon steel, the mass of each compact is calculated to be 3.676kg, the pressure of each of the four regions of the wafer is 36N, and the distribution condition of the contact stress between the wafer and the polishing pad is obtained through simulation analysis, as shown in fig. 7. As is evident from fig. 7: the stress is increased sharply at the edge of the wafer, and the difference between the maximum stress and the minimum stress is 2159.2Pa, so that when the uniform load is applied, the edge effect occurs after the wafer is polished, and the edge effect and the simulation result are in accordance with the actual situation.
The Ansys software is used for simulation, and the distribution of the contact stress of the pressing blocks with different densities is analyzed, and the result is shown in fig. 8. When the density of the briquette is cast carbon steel, cast stainless steel, gray cast iron, zinc-aluminum alloy, titanium alloy and aluminum, the pressure to the wafer is calculated to be 36N, 35.6N, 33N, 29N, 21.9N and 12.5N respectively. It can be seen from fig. 8 that the stress distributions obtained by combining different density blocks are also different.
FIG. 8 (e) shows: the pressures applied to the wafer from the first pressure block to the fourth pressure block are 36N, 35.6N, 33N and 29N respectively, the obtained maximum contact stress is 5003.7Pa, the obtained minimum contact stress is 3419.5Pa, the difference between the maximum contact stress and the minimum contact stress is 1584.2Pa, and the difference is smaller than the extreme difference 2159.2Pa in the figure 7.
It can also be seen from fig. 8 (c): when the density of the first pressing block to the fourth pressing block is sequentially reduced and the reduction amplitude is increased, the edge effect of the wafer is greatly improved, but the difference between the maximum contact stress and the minimum contact stress is large, and the middle of the wafer becomes concave after being processed. Therefore, the proper sub-area applied load can be selected according to the surface shape precision of the wafer before polishing so as to eliminate the influence of the initial surface shape error of the wafer.
4) And determining the material of the pressing block. As can be seen from the analysis results of fig. 8: when the surface shape error before wafer polishing is not considered, the contact stress distribution is more uniform when the applied loads from the first to fourth compacts are 36N, 35.6N, 33N, and 29N in this order, so that the materials of the first to fourth compacts can be selected to be cast carbon steel, cast stainless steel, gray cast iron, and zinc-aluminum alloy in this order when the divisional pressure is set to 4 regions for 8-inch single crystal silicon. The size of the briquetting is: radius R of first press piece 54 1 =50mm; outer diameter R of second press block 55 2 =70.7mm, inner diameter R 1 =50mm; outer diameter R of third press block 56 3 =86.6mm, internal diameter R 2 =70.7mm; outer diameter R of fourth press block 57 4 =100mm, inner diameter R 3 =86.6mm; the height h of each briquette is 60mm.
5) And manufacturing a pressing device. According to the determined material and size of the pressing block, a first pressing block 54, a second pressing block 55, a third pressing block 56 and a fourth pressing block 57 are processed in sequence. The pressing blocks are sequentially arranged in the shell 51 and arranged according to the radius, the fixing plate 53 is fastened by using screws, no relative movement between the pressing blocks is ensured, and the pressing device 5 is assembled.
6) The pressure control device is assembled. A wafer 4 to be processed, which is to be polished, is stuck below the housing 51 of the pressing device 5 using paraffin, and then the pressing device 5 is moved onto the polishing pad 3. The workpiece shaft 9 is moved to bring the jig 6 close to the pressing device 5, and the clamp blocks 64 are brought into contact with the bottom side surface of the housing 51 of the pressing device 5 by manually adjusting the adjustment plate 62, so that the torque can be transmitted to the pressing device 5 when the workpiece shaft 9 is rotated, thereby achieving the rotation of the wafer 4 to be processed. The rotation of the polishing disc 2 is controlled by the polishing spindle 1. The polishing pressure of the wafer 4 to be processed is provided by the pressing device 5, and the rotation speed is controlled by the workpiece shaft 9. During polishing, the workpiece shaft 9 and the polishing shaft 1 are set to rotate in the same direction and at the same speed, and polishing liquid is supplied to set the polishing time for polishing.
Verification experiment of polishing experiment
Using two 8-inch silicon wafers, the initial areal precision PV value (Peak-to-Valley value) was 1 λ (1 λ =632.8 nm), and the applied pressure used two modes: in the first mode, loads are uniformly distributed in 36N; mode two, different zones control the load, with the pressures for zones 1 through 4 being 36N, 35.6N, 33N, 29N, respectively.
Setting polishing parameters: the rotating speed is 40r/min, the flow rate of the polishing solution is 100ml/min, the polishing solution is 80nm silica sol, and the polishing time is 1h. The surface shape precision detection instrument is a U.S. ZYGO laser interferometer. The results of the experiment are shown in fig. 9 and 10.
FIG. 9 shows the figure-of-area accuracy PV value of 0.48 λ after the mode one machining, and FIG. 10 shows the figure-of-area accuracy PV value of 0.26 λ after the mode two machining. Therefore, as can be seen from fig. 9 and 10: under the same experiment condition, the polishing effect with better precision can be obtained by controlling the regional pressure, and the practicability and the effectiveness of the wafer polishing pressure applying device, the control device and the control method provided by the embodiment of the invention are verified.
Example four
The present embodiment provides a polishing apparatus which is different from the prior art in that: the wafer polishing pressure control device of the polishing apparatus provided in this embodiment is the wafer polishing pressure control device provided in the second embodiment of the present invention.
Therefore, the simple pressing device and the pressure control device for applying pressure in different areas for wafer polishing provided by the embodiment of the invention realize stable gravity loading by adopting pressing blocks made of different materials as area-by-area pressing carriers, ensure the stability of polishing pressure in the wafer polishing process, contribute to improving the surface shape precision of wafer processing and reduce the rejection rate.
The core of the wafer polishing pressure control method provided by the embodiment of the invention is that the equal-volume pressing block is adopted, and the pressure control is realized by changing the density of the pressing block.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (12)
1. A wafer polishing and pressing device is characterized in that: the wafer processing device comprises a shell, N pressing blocks made of different materials and a pressing block fixing element, wherein the pressing blocks and the pressing block fixing element are arranged in the shell, the shell is a cylindrical groove with an open top end, and a wafer to be processed can be stuck to the bottom end of the cylindrical groove; the N pressing blocks are arranged concentrically and have equal volume; the pressing block fixing element is arranged at the top ends of the pressing block and the shell and is matched with the shell to fixedly install the N pressing blocks in the shell, and N is a natural number larger than or equal to 3.
2. The pressure applicator of claim 1, wherein: the N pressing blocks consist of a columnar pressing block positioned in the center and N-1 pressing block rings concentrically arranged with the columnar pressing block, and the heights of the columnar pressing block and the pressing block rings are equal; wherein the radius of the columnar pressing block isR 1 Outer ring radius of said pressure block ring
N represents the nth briquetting, and N is more than or equal to 2 and less than or equal to N.
3. The pressing device according to claim 2, wherein: the pressing block fixing element is a fixing plate, and the center of the fixing plate is fixed at the center of the columnar pressing block.
4. The pressing device according to claim 1, 2 or 3, wherein: each pressing block is provided with a blind hole, and a screw can be installed in the blind hole.
5. The pressing device according to claim 1, 2 or 3, wherein: and the N pressing blocks are provided with carrying lifting rings.
6. A wafer polishing pressure control device is characterized in that: the polishing device comprises a polishing shaft component, a workpiece shaft component, a clamp and the pressing device according to any one of claims 1-5, wherein the polishing shaft component rotates to polish the wafer to be processed, the workpiece shaft component is connected with the clamp through a coupler, the pressing device is clamped in the clamp, and the workpiece shaft component carries the pressing device to rotate through the coupler and the clamp.
7. The pressure control device according to claim 6, characterized in that: the clamp comprises a clamp body, an adjusting plate, a connecting plate and a clamping block, and the center of the clamp body is connected with one end of the coupler; the adjusting plate is arranged on the clamp body; the upper end of the connecting plate is arranged on the adjusting plate, and the lower end of the connecting plate is connected with the clamping block; the clamping block carries the connecting plate through the adjusting plate to clamp and fix the pressure applying device, so that the pressure applying device rotates along with the coupler.
8. The pressure control device according to claim 7, characterized in that: an adjusting groove is formed in the middle of the adjusting plate, and the position of the adjusting plate is adjusted through the adjusting groove, so that the clamping block clamps and fixes the pressure applying device.
9. The pressure control device according to claim 8, characterized in that: the clamping blocks are matched with the shell to fix the pressure applying device in the clamp.
10. The pressure control device according to claim 7, characterized in that: a plurality of lightening holes are uniformly formed in the fixture body.
11. A wafer polishing pressure control method, comprising:
1) Determining wafer size and pressure control zone Z n The number of the (c) component(s),the radius of the pressing blocks with equal volumes is obtained by analytical calculationR n Values, wherein N represents the nth compact and N is greater than or equal to 2 and less than or equal to N;
2) Selecting a plurality of materials as materials for preparing a pressing block, setting polishing pressure, and calculating roundness under the condition that the pressure of each subarea is equal to obtain a height value h of the pressing block;
3) Finite element software Ansys is used for simulating and analyzing the influence of different applied loads on the contact stress, the uniform distribution of the contact stress is met as far as possible as a standard, and the sub-region Z is determined n Applying a load;
4) According to a determined sub-zone Z n Determining the proper sub-region Z n Density value rho of the pressing block;
5) Manufacturing corresponding compacts according to the determined material and size of the compacts, assembling the compacts into the pressing device according to any one of claims 1 to 5, and assembling the pressing device, the workpiece shaft member, the polishing shaft member and the jig into the pressure control device according to any one of claims 6 to 10 for controlling the wafer polishing pressure.
12. A polishing apparatus characterized by: comprising a pressure control device according to any one of claims 6 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211242769.5A CN115890472A (en) | 2022-10-11 | 2022-10-11 | Wafer polishing pressure control method, pressure applying device, control device and polishing equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211242769.5A CN115890472A (en) | 2022-10-11 | 2022-10-11 | Wafer polishing pressure control method, pressure applying device, control device and polishing equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115890472A true CN115890472A (en) | 2023-04-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211242769.5A Pending CN115890472A (en) | 2022-10-11 | 2022-10-11 | Wafer polishing pressure control method, pressure applying device, control device and polishing equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115890472A (en) |
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2022
- 2022-10-11 CN CN202211242769.5A patent/CN115890472A/en active Pending
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