CN115454158A - Device and method for adjusting and controlling grinding pressure - Google Patents
Device and method for adjusting and controlling grinding pressure Download PDFInfo
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- CN115454158A CN115454158A CN202211157603.3A CN202211157603A CN115454158A CN 115454158 A CN115454158 A CN 115454158A CN 202211157603 A CN202211157603 A CN 202211157603A CN 115454158 A CN115454158 A CN 115454158A
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Abstract
The invention discloses a device and a method for adjusting and controlling grinding pressure, wherein a pressure sensing sheet is attached to a grinding head to obtain first output pressure and second output pressure of a plurality of pressure partitions of the grinding head, wherein the first output pressure corresponds to initial input pressure of the pressure partitions, and the second output pressure corresponds to input pressure after the pressure partitions are adjusted; the control module is used for determining the adjustment ratio of the output pressure of the pressure zones according to the ground thickness measurement value of the process zones corresponding to the pressure zones on the ground object, adjusting the initial input pressure of the pressure zones to the target input pressure, enabling the pressure change rate of the second output pressure relative to the first output pressure to be consistent with the adjustment ratio, and then carrying out mass production grinding on the target input pressure, so that the pressure of each zone can be adjusted more accurately, the optimal flattening effect is achieved, the pressure adjustment efficiency is improved, and the risk of misadjustment is reduced.
Description
Technical Field
The present invention relates to the field of semiconductor integrated circuit technology, and more particularly, to a device and method for adjusting and controlling polishing pressure.
Background
In the chemical mechanical polishing in the chip manufacturing process, the appearance of the surface of a wafer is controlled based on the pressure applied to the wafer by a polishing head in the wafer polishing process.
The chemical mechanical polishing has the characteristics of large polishing removal amount and high requirement on thickness and appearance. The grinding head is directly contacted with the wafer in the grinding process, and pressure is applied to the back of the wafer through the grinding head, so that the surface appearance of the crystal face film quality is controlled, and a better planarization effect is achieved. Therefore, the pressure control of the polishing head plays an important role in maintaining the film thickness and planarization of the wafer during the polishing process.
With the continuous upgrading of the process, the requirements of the chemical mechanical polishing on the surface topography are higher and higher, and the number of the air chambers arranged on the polishing head for performing pressure zone control is also upgraded from the initial 3 air chambers and 5 air chambers to the current 7 air chambers. Furthermore, 1 air chamber for overall pressure control of the retaining ring is provided. Due to the increasing number of pressure zones, the pressure control area of each process zone in the process is smaller and smaller, and therefore the mutual influence of the pressures between the adjacent pressure zones is larger and larger.
At present, aiming at the detection of the pressure of a grinding head, only the input pressure at the air inlet of each air chamber can be detected, namely the actual output pressure acted on the corresponding area of a wafer by each air chamber cannot be accurately expressed. This makes the pressure adjustment for each process section on the polishing process recipe relatively uncontrollable, often relying on experience and multiple attempts to achieve polishing planarization control. Therefore, the conventional polishing pressure adjustment requires a lot of time and consumes a lot of wafers and consumables for performing the pressure adjustment experiment, and the efficiency is low.
Disclosure of Invention
The present invention is directed to overcoming the above-mentioned deficiencies of the prior art and providing an apparatus and method for polishing pressure adjustment control.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention provides a device for adjusting and controlling grinding pressure, which comprises:
the pressure sensing sheet is attached to the lower surface of the grinding head and used for acquiring first output pressure and second output pressure of a plurality of pressure zones of the grinding head, the first output pressure corresponds to initial input pressure of the pressure zones, and the second output pressure corresponds to input pressure after the pressure zones are adjusted;
the control module is used for determining the adjustment ratio of the output pressure of the pressure subareas according to the grinded thickness measured values of the process subareas corresponding to the pressure subareas on the grinding object; and adjusting the initial input pressure to a target input pressure for the plurality of pressure zones such that a rate of change in pressure of the second output pressure relative to the first output pressure corresponds to the adjustment rate.
Furthermore, the pressure sensing piece comprises a substrate and a pressure sensing module arranged on the back surface of the substrate, the pressure sensing module is provided with a plurality of pressure sensing units, and the vertical projection area of each pressure subarea comprises at least one pressure sensing unit.
Further, the pressure sensing units are arranged on the back surface of the substrate to form a pressure sensing unit array; or the pressure sensing units are arranged on the back surface of the substrate to form a plurality of pressure sensing unit coils which are sequentially expanded from the center of the substrate to the outside.
Further, the pressure sensing unit is coupled with the control module; the control module is used for calculating a group of thickness difference rate data between the ground thickness measurement values and a reference thickness, and taking each thickness difference rate as an adjustment rate of the output pressure of the plurality of pressure zones.
Further, the reference thickness is a measured thickness value after grinding of one process zone in the plurality of process zones; or the reference thickness is the average value of the thickness measurement values after grinding of the plurality of process partitions.
The invention also provides a method for adjusting and controlling the grinding pressure, which comprises the following steps:
determining the adjustment ratio of the output pressure of a plurality of pressure subareas according to the thickness measurement values after grinding of a plurality of process subareas corresponding to the plurality of pressure subareas of the grinding head on the grinding object;
obtaining a first output pressure of the plurality of pressure partitions, the first output pressure corresponding to an initial input pressure of the plurality of pressure partitions;
and adjusting the initial input pressure of the plurality of pressure zones and acquiring a second output pressure of the plurality of pressure zones during pressure adjustment until the pressure change rate of the second output pressure relative to the first output pressure is consistent with the adjustment rate.
Further, the determining, according to the post-polishing thickness measurement values of a plurality of process partitions corresponding to a plurality of pressure partitions of the polishing head on the polishing object, an adjustment ratio of output pressures of the plurality of pressure partitions specifically includes:
obtaining the thickness measured values of the ground process subareas on the ground object through grinding;
calculating a group of thickness difference rate data between the ground thickness measurement values and a reference thickness;
determining each of the thickness difference rates as an adjustment ratio of the output pressures of the plurality of pressure zones.
Further, the reference thickness is a post-grinding thickness measurement of one of the plurality of process zones; or, the reference thickness is a mean value of the thickness measurement values after grinding of the plurality of process partitions.
Further, the acquiring the first output pressures of the plurality of pressure partitions and the acquiring the second output pressures of the plurality of pressure partitions during pressure adjustment specifically include:
attaching a pressure sensing sheet to the lower surface of the grinding head, and obtaining the first output pressure and the second output pressure of each pressure partition through simulated grinding;
the adjusting the initial input pressure of the plurality of pressure partitions specifically includes:
adjusting the initial input pressures of the plurality of pressure zones in accordance with the adjustment direction indicated by the adjustment ratio until the change rate of the second output pressure relative to the first output pressure is in accordance with the adjustment ratio, and terminating the adjustment;
and grinding the product by adopting the input pressure of the pressure subareas obtained when the adjustment is finished as the target input pressure.
Furthermore, the pressure sensing piece comprises a substrate and a pressure sensing module arranged on the back surface of the substrate, the pressure sensing module is provided with a plurality of pressure sensing units, and the vertical projection area of each pressure subarea comprises at least one pressure sensing unit.
According to the technical scheme, the pressure sensing sheet is attached to the lower surface of the grinding head, the output pressure from each pressure subarea on the grinding head is obtained through simulated grinding, the actual output pressure from each pressure subarea when the product is ground is represented, and therefore the actual pressure state of the product when the product is pressed by the grinding head can be more accurately represented. Furthermore, according to the thickness measurement value after grinding of each process subarea of the grinding object, the adjusting ratio of the output pressure of each pressure subarea is determined, and the target input pressure of each pressure subarea is obtained through the relation between the output pressure change rate of each pressure subarea and the adjusting ratio obtained after and before the input pressure is adjusted by the pressure sensing piece, so that subsequent products are ground, and the pressure of each area is adjusted more accurately. Compared with the traditional mode of experience adjustment and continuous overpressure trial, the method disclosed by the invention is more ideal for controlling the surface appearance in the product grinding process, can realize the optimal flattening effect, and can adjust the required optimal pressure more quickly and accurately, so that the pressure adjustment efficiency is improved, and the risk of error adjustment is reduced.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for polishing pressure adjustment control according to a preferred embodiment of the present invention;
fig. 2-3 are schematic structural views of a pressure-sensitive sheet according to a preferred embodiment of the invention;
FIG. 4 is a flow chart illustrating a method for polishing pressure adjustment control according to a preferred embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and similar words are intended to mean that the element or item preceding the word comprises the element or item listed after the word and its equivalent, but not the exclusion of other elements or items.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an apparatus for adjusting and controlling a polishing pressure according to a preferred embodiment of the invention. As shown in fig. 1, an apparatus for adjusting and controlling a polishing pressure according to the present invention may include a pressure sensing plate 20 and a control module 30 disposed on a polishing head 10 of a polishing apparatus.
The polishing head 10 is provided with a plurality of air chambers 103 for performing pressure zone control, for example, seven air chambers Z1 to Z7, at positions inside the bottom surface thereof, but the present invention is not limited thereto. Each air chamber Z1-Z7 is distributed from the center to the outside along the bottom surface of the grinding head 10 in sequence to form a closed ring-shaped arrangement, including a first air chamber Z1 located at the center of the bottom surface of the grinding head 10, and a second air chamber Z2, a third air chamber Z3, a fourth air chamber Z4, a fifth air chamber Z5, a sixth air chamber Z6 and a seventh air chamber Z7 located outside the first air chamber Z1 in sequence, so that seven pressure partitions distributed from the center to the outside in sequence are correspondingly formed on the bottom surface of the grinding head 10, namely: a first pressure zone corresponding to the first air chamber Z1, a second pressure zone corresponding to the second air chamber Z2, a third pressure zone corresponding to the third air chamber Z3, a fourth pressure zone corresponding to the fourth air chamber Z4, a fifth pressure zone corresponding to the fifth air chamber Z5, a sixth pressure zone corresponding to the sixth air chamber Z6, and a seventh pressure zone corresponding to the seventh air chamber Z7.
Thus, seven process sections Y1 to Y7 corresponding to the pressure sections (gas chambers 103) can be defined on the polishing target: a first process zone Y1 corresponding to the first pressure zone (first air chamber Z1), a second process zone Y2 corresponding to the second pressure zone (second air chamber Z2), a third process zone Y3 corresponding to the third pressure zone (third air chamber Z3), a fourth process zone Y4 corresponding to the fourth pressure zone (fourth air chamber Z4), a fifth process zone Y5 corresponding to the fifth pressure zone (fifth air chamber Z5), a sixth process zone Y6 corresponding to the sixth pressure zone (sixth air chamber Z6), and a seventh process zone Y7 corresponding to the seventh pressure zone (seventh air chamber Z7).
The polishing head 10 is also provided with an eighth air chamber 101 for performing overall pressure control of the retainer ring 102.
The indirect control of the actual pressure applied to the corresponding process division is realized by adjusting the input pressure (inlet pressure) of each pressure division (each air chamber 103) on the grinding head 10.
The knowledge about the polishing head and the polishing apparatus can be understood by referring to the prior art.
The grinding object can be a circular sheet product, such as a wafer product. Alternatively, the object to be ground may be a sheet-like product having another shape. The present invention will be described below by taking the adjustment and control of the polishing pressure for a wafer product as an example.
Please refer to fig. 1. The pressure-sensitive sheet 20 may have a sheet structure with the same dimension as the actual wafer product (including the wafer test sheet), so as to more accurately simulate the actual polishing state of the wafer product. Accordingly, the pressure sensitive sheet 20 is also divided into the seven process sections Y1 to Y7 corresponding to the positions on the wafer product. Taking the wafer product size as 300mm as an example, the pressure-sensitive sheet 20 can also be made with a diameter of 300mm and a thickness similar to the wafer product.
When the polishing pressure needs to be adjusted and controlled, the actual pressure applied to the corresponding area of the wafer product by the polishing head 10 cannot be accurately represented by detecting the pressure at the air inlet of each air chamber 103, so that the output pressure data of each pressure zone on the polishing head 10 can be obtained by using the pressure sensing sheet 20.
In a specific manner, when in use, the pressure-sensitive sheet 20 may be used to replace a wafer product, and the back surface of the pressure-sensitive sheet 20 is attached to the lower surface of the polishing head 10 to simulate the actual polishing state of the wafer product, and by simulating the polishing, the actual pressure (i.e., the output pressure of each pressure zone) formed by the pressure action of each pressure zone on the polishing head 10 is sensed by using the pressure state of the pressure-sensitive sheet 20 in contact with the polishing pad, and pressure data is acquired.
Further, the pressure-sensitive sheet 20 may be used to obtain a first output pressure from each pressure zone of the polishing head 10, where the first output pressure is the output pressure of each pressure zone obtained by the pressure-sensitive sheet 20 when the input pressure of each pressure zone is the initial input pressure.
In an alternative embodiment, before the pressure-sensitive sheet 20 is used, the wafer test sheet may be used to perform a debugging stage of polishing to obtain the post-polishing thickness measurement values of the process zones Y1 to Y7 corresponding to the pressure zones on the wafer test sheet. The control module 30 may further determine an adjustment ratio of the output pressure of each pressure zone according to the thickness measurement values after polishing of each process zone Y1 to Y7.
After the pressure-sensitive sheets 20 are used to obtain the first output pressure of each pressure zone of the polishing head 10, and the control module 30 determines the adjustment ratio of the output pressure of each pressure zone, the control module 30 performs pressure adjustment on the initial input pressure of each pressure zone, and then may continue to obtain the second output pressure from each pressure zone through the pressure-sensitive sheets 20. The second output pressure is the output pressure of each pressure sub-area obtained by the pressure-sensitive sheet 20 after the input pressure of each pressure sub-area is adjusted. The control module 30 can continuously adjust the input pressure of each air chamber 103 of the polishing head 10 until the pressure change rate of the second output pressure relative to the first output pressure is consistent with the adjustment ratio.
In a preferred embodiment, the pressure sensor 20 is coupled to the control module 30 to provide a feedback of the sensed pressure signal to the control module 30. The control module 30 is connected to a pressure adjusting device of the polishing head 10. The control module 30 may be provided on the polishing apparatus. The control module 30 is configured to calculate a set of thickness difference rate data between the ground thickness measurement value of each process zone Y1 to Y7 and a reference thickness according to the ground thickness measurement value of each process zone Y1 to Y7, which is obtained by actual measurement after grinding the wafer test piece. The control module 30 adjusts the input pressure of each pressure zone by the pressure adjusting device of the polishing head 10 using each thickness difference rate as an adjustment rate of the output pressure for each pressure zone until the change rate of the second output pressure with respect to the first output pressure matches the adjustment rate.
When the change rate of the second output pressure relative to the first output pressure is consistent with the adjustment rate, the control module 30 uses the input pressure of each pressure partition as the menu pressure input value for actual polishing of the wafer product.
In an alternative embodiment, the reference thickness may be the post-polishing thickness measurement of one of the seven process zones Y1 to Y7 on the wafer test piece, for example, the reference thickness may be the post-polishing thickness measurement of the first process zone Y1.
In an alternative embodiment, the reference thickness may be the average of the post-polishing thickness measurements for the seven process zones Y1-Y7 on the test piece.
Please refer to fig. 2. In a preferred embodiment, the pressure-sensitive sheet 20 may include a substrate 201 and a pressure-sensitive module disposed on a back surface of the substrate 201. The pressure sensing module may have a plurality of pressure sensing units 202. When the pressure sensitive sheet 20 is attached to the polishing head 10, at least one pressure sensitive cell 202 is provided in the vertical projection area of each pressure zone, that is, the pressure sensitive cells 202 are provided at positions corresponding to the process zones Y1 to Y7 on the pressure sensitive sheet 20, and vertically correspond to the positions of the pressure zones on the polishing head 10, so that the output pressure from each pressure zone can be detected.
In an alternative embodiment, the number of corresponding pressure-sensing cells 202 on the pressure-sensing strip 20 located below each pressure zone may be the same. For example, one or more pressure sensing units 202 may be equally disposed on each process partition of the pressure sensing sheet 20.
In an alternative embodiment, the number of corresponding pressure-sensing cells 202 on the pressure-sensing strip 20 located below each pressure zone may also be different. For example, as illustrated in fig. 2, one pressure sensing unit 202 (for example, the left side of the center of the pressure sensing sheet 20) is disposed on each of the first process partition Y1, the second process partition Y2, and the fifth to seventh process partitions Y5 to Y7, three pressure sensing units 202 are disposed on the third process partition Y3, and two pressure sensing units 202 are disposed on the fourth process partition Y4. But is not limited thereto.
It should be noted that, since the pressure zones and the process zones form a ring, the pressure sensing units 202 on each process zone can be distributed in an expanded manner on the ring-shaped process zone for more precise acquisition of the output pressure data. Fig. 2 is only a reference state for explaining the arrangement of the pressure sensing unit 202.
In other alternative embodiments, the corresponding pressure-sensitive cells 202 on the pressure-sensitive sheet 20 located below each pressure zone are the same size.
Further, the size of the corresponding pressure sensing unit 202 on the pressure sensing sheet 20 located under each pressure zone may also be different. For example, as illustrated in fig. 2, since the horizontal regions of the first and second process partitions Y1 and Y2 are relatively wide, the pressure sensing units 202 having a larger size may be respectively disposed on the first and second process partitions Y1 and Y2, and the pressure sensing units 202 having a smaller size may be respectively disposed on the other process partitions, but not limited thereto.
In an example, taking a wafer size of 300mm as an example, the horizontal width of the smallest region of the seventh process zone Y7 may be as small as, for example, less than 5mm, and the pressure sensing unit 202 correspondingly disposed in the seventh process zone Y7 of the pressure sensing sheet 20 may have a size of, for example, 2 × 2mm, so as to achieve pressure detection on a smaller area.
Please refer to fig. 3. In a preferred embodiment, the pressure sensing units 202 are arranged on the back surface of the substrate 201 to form an array of pressure sensing units, so that the output pressure data of each pressure zone can be obtained more accurately. With this arrangement, the averaged calculation result can be used as the output pressure data of each pressure zone for the output pressure signals fed back from each pressure sensing unit 202 on each process zone. The calculation can also be performed by a common statistical means such as a weighted average or an average of several maxima. The mapping state of each pressure zone corresponding to each process zone Y1 to Y7 on the pressure-sensitive sheet 20 is shown in a dotted circle in fig. 3.
The array form of the pressure sensing cells 202 shown in fig. 3 is only for convenience of understanding when describing the embodiment of the present invention, and should not be understood as an actual configuration form of the pressure sensing cell array.
In a preferred embodiment, the pressure sensing elements 202 may be arranged on the back side of the substrate 201 to form a plurality of concentric circles of pressure sensing elements that extend sequentially from the center of the substrate 201 outward. That is, each pressure sensing unit loop is formed by surrounding a plurality of pressure sensing units 202 into a loop shape. Wherein a center pressure sensing unit 202 may be disposed at a center of the substrate 201.
In a preferred embodiment, the pressure sensing unit 202 may be a piezoelectric sensor. The pressure can be sensitively sensed by using a sensor in a piezoelectric form, and the received pressure can be fed back to a voltage value and transmitted to the control module 30 for recording data.
In an alternative embodiment, the pressure sensing unit 202 may be embedded on the back surface of the substrate 201.
In an alternative embodiment, the pressure sensing unit 202 can also be directly formed on the back surface of the substrate 201 by using a semiconductor process.
In an alternative embodiment, a protective film layer may be further disposed on the pressure sensing unit 202 on the back surface of the substrate 201.
A method for adjusting and controlling a grinding pressure according to the present invention will be described in detail with reference to the accompanying drawings and embodiments.
Please refer to fig. 4 in conjunction with fig. 1. The method for adjusting and controlling the grinding pressure can be realized by the device for adjusting and controlling the grinding pressure, and comprises the following steps:
step S1: and determining the adjustment ratio of the output pressure of each pressure subarea according to the polished thickness measurement values of the process subareas Y1-Y7 corresponding to the pressure subareas on the polishing head 10 on the wafer experiment sheet.
In a preferred embodiment, a wafer lab wafer may be used and the conditioning stage polishing is performed according to the menu pressure initial settings. After polishing, the wafer test piece can be taken out from the polishing device for thickness measurement, and the polished thickness measurement values of the process zones Y1 to Y7 on the wafer test piece corresponding to the pressure zones on the polishing head 10 are obtained. Wherein, the thickness after grinding of each process subarea Y1-Y7 can be measured in multiple points, and the calculation result of taking the average value can be used as the data of the thickness after grinding of each process subarea Y1-Y7.
The ground thickness measurement values of the process partitions Y1 to Y7 can also be calculated by taking a weighted average mode or a mode of taking the average value of a plurality of ground thickness measurement maximum values.
The control module 30 calculates the difference between each grinded thickness measurement value and the selected reference thickness to obtain the thickness difference rate data (unit is percentage) between each grinded thickness measurement value and the reference thickness. When the ground thickness measurement value of a certain process subarea is greater than the reference thickness, the calculated thickness difference rate of the process subarea is a positive value; and conversely, when the thickness measured value of a certain process subarea after grinding is smaller than the reference thickness, the calculated thickness difference rate of the process subarea is a negative value.
At this time, the control module 30 determines the calculated thickness difference rate of each process zone Y1 to Y7 as an adjustment rate (in percentage) of the output pressure from each pressure zone to which the product is subjected during grinding.
According to the linear and proportional corresponding relation between the grinding speed and the grinding pressure, the linear and proportional corresponding relation between the thickness difference rate and the adjustment ratio of the grinding pressure can be deduced. Therefore, the thickness difference ratio of each process division Y1 to Y7 calculated as described above can be applied to actual adjustment control of the grinding pressure as an adjustment ratio of the output pressure of each pressure division.
Note that both the adjustment ratio and the thickness difference ratio have signs. For example, when the thickness difference rate is negative, it indicates that the polishing rate of a process partition is greater than the polishing rate corresponding to the reference thickness, so the polishing rate of the process partition needs to be adjusted to be consistent with the polishing rate corresponding to the reference thickness. At this time, the actual input pressure of the corresponding pressure zone should be reduced by the value of the thickness variation rate. That is, the adjustment ratio is also a negative value of the same magnitude as the thickness variation ratio.
Step S2: and acquiring the first output pressure of each pressure subarea through the pressure sensing piece.
In a preferred embodiment, the pressure-sensitive sheet 20 can be used to attach the back surface of the pressure-sensitive sheet 20 having the pressure-sensitive units 202 to the lower surface of the polishing head 10.
Then, according to the same menu pressure initial setting value as the wafer test piece, the pressure sensing piece 20 is pressed on the polishing pad by using the initial input pressure of each pressure partition for simulation polishing.
In the simulated grinding process, the first output pressure signals of the pressure zones are collected by the pressure sensing piece 20 and transmitted to the control module 30. The control module 30 uses the obtained first output pressure as an initial actual output pressure for polishing, and can be used as an initial pressure input value when performing PID control on the polishing pressure.
And step S3: and adjusting the input pressure of each pressure subarea and acquiring the second output pressure of each pressure subarea during pressure adjustment until the pressure change rate of the second output pressure relative to the first output pressure is consistent with the adjustment rate.
The control module 30 adjusts the input pressure of each pressure section by the pressure adjusting device of the polishing head 10.
When the polishing pressure adjustment control is performed, the input pressure of each pressure section is adjusted in magnitude in accordance with the adjustment direction indicated by the adjustment ratio. For example, when the adjustment ratio is a negative value, it indicates that the adjustment in the decreasing direction should be made to the input pressure of the corresponding pressure section. And vice versa.
For example, if the thicknesses of the regions Y4 to Y6 of the fourth to sixth process zones on the wafer test piece are all 10% thinner than the thickness of the first process zone Y1 serving as the reference thickness, that is, the thickness difference rates of the fourth process zone Y4 to the sixth process zone Y6 are all-10%, the adjustment rates are all-10%. When the pressure is adjusted, the input pressures of the fourth to sixth air chambers Z4 to Z6 located in the fourth to sixth pressure divisions are adjusted in the decreasing direction until the rate of change of the first output pressure and the second output pressure of the fourth to sixth air chambers Z4 to Z6 fed back by the pressure sensing piece 20 is also decreased by 10%.
When the input pressure of the corresponding pressure partition is adjusted, the pressure sensing piece 20 continuously collects the varied second output pressure signals from the pressure partitions, and feeds the varied second output pressure signals back to the control module 30 in real time.
The control module 30 continuously compares the second output pressure of each pressure zone with the first output pressure, and calculates the change rate of the second output pressure relative to the first output pressure. When the rate of change of the second output pressure relative to the first output pressure is consistent with the determined adjustment rate through pressure adjustment, the control module 30 will issue an adjustment stop command to terminate the adjustment.
Based on the correspondence relationship between the second output pressure and the input pressure of the pressure section, when the control module 30 acquires the second output pressure when the adjustment ratio is satisfied, the target input pressure of the corresponding pressure section is obtained. At this time, the control module 30 performs mass production polishing by using the target input pressure of each pressure zone obtained at the end of adjustment as a menu pressure input value (target value) for subsequently performing actual polishing on the wafer product, by the pressure adjusting device of the polishing head 10.
In summary, the pressure-sensitive sheet 20 is attached to the lower surface of the polishing head 10, and the output pressure from each pressure zone of the polishing head 10 is obtained by simulated polishing to represent the actual output pressure from each pressure zone when the product is polished, so as to more accurately represent the actual pressure state when the product is pressed by the polishing head 10. Further, according to the thickness measurement values of the process partitions Y1-Y7 of the experimental sheet after grinding and the calculated thickness difference rate, the adjusting rate of the output pressure of each pressure partition is determined, and the target input pressure of each pressure partition is obtained through the relation between the adjusting rate and the output pressure change rate of each pressure partition acquired by the pressure sensing sheet 20 after and before the input pressure is adjusted, so that subsequent products are ground, and the pressure of each area is adjusted more accurately. Compared with the traditional mode of adjusting by experience and trying without continuous overpressure, the invention has more ideal control on the surface appearance in the product grinding process, can realize the optimal flattening effect, and can adjust the required optimal pressure more quickly and accurately, thereby improving the pressure adjustment efficiency and reducing the risk of misadjustment.
Although the embodiments of the present invention have been described in detail hereinabove, it is apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention as described herein is capable of other embodiments and of being practiced or of being carried out in various ways.
Claims (10)
1. An apparatus for grinding pressure adjustment control, comprising:
the pressure sensing sheet is attached to the lower surface of the grinding head and used for acquiring first output pressure and second output pressure of a plurality of pressure zones of the grinding head, the first output pressure corresponds to initial input pressure of the pressure zones, and the second output pressure corresponds to input pressure after adjustment of the pressure zones;
the control module is used for determining the adjustment ratio of the output pressure of the pressure subareas according to the grinded thickness measured values of the process subareas corresponding to the pressure subareas on the grinding object; and adjusting the initial input pressure to a target input pressure for the plurality of pressure zones such that a rate of change of pressure of the second output pressure relative to the first output pressure coincides with the adjustment ratio.
2. The apparatus of claim 1, wherein the pressure-sensitive strip comprises a substrate and a pressure-sensitive module disposed on a back surface of the substrate, the pressure-sensitive module is provided with a plurality of pressure-sensitive cells, and a vertical projection area of each of the pressure zones contains at least one of the pressure-sensitive cells.
3. The apparatus of claim 2, wherein the pressure sensing units are arranged on the back surface of the substrate to form an array of pressure sensing units; or the pressure sensing units are arranged on the back surface of the substrate to form a plurality of pressure sensing unit coils which are sequentially expanded from the center of the substrate to the outside.
4. The apparatus as claimed in claim 2, wherein the pressure sensing unit is coupled to the control module; the control module is used for calculating a group of thickness difference rate data between the ground thickness measurement values and a reference thickness, and taking each thickness difference rate as an adjustment rate of the output pressure of the plurality of pressure zones.
5. The apparatus of claim 4, wherein the reference thickness is a post-mill thickness measurement of one of the plurality of process zones; or, the reference thickness is a mean value of the thickness measurement values after grinding of the plurality of process partitions.
6. A method for adjusting control of polishing pressure, comprising:
determining the adjustment ratio of the output pressure of a plurality of pressure subareas according to the thickness measurement values after grinding of a plurality of process subareas corresponding to the plurality of pressure subareas of the grinding head on the grinding object;
obtaining a first output pressure of the plurality of pressure partitions, the first output pressure corresponding to an initial input pressure of the plurality of pressure partitions;
and adjusting the initial input pressure of the plurality of pressure zones and acquiring second output pressure of the plurality of pressure zones during pressure adjustment until the pressure change rate of the second output pressure relative to the first output pressure is consistent with the adjustment rate.
7. The apparatus according to claim 6, wherein the determining the adjustment ratio of the output pressures of the plurality of pressure zones according to the measured values of the post-polishing thicknesses of the plurality of process zones corresponding to the plurality of pressure zones of the polishing head on the polishing object specifically comprises:
obtaining the thickness measured values of the ground process subareas on the ground object through grinding;
calculating a group of thickness difference rate data between the ground thickness measurement values and a reference thickness;
determining each of the thickness difference rates as an adjustment ratio of the output pressures of the plurality of pressure zones.
8. The apparatus of claim 7, wherein the reference thickness is a post-mill thickness measurement of one of the plurality of process zones; or the reference thickness is the average value of the thickness measurement values after grinding of the plurality of process partitions.
9. The apparatus of claim 6, wherein the obtaining a first output pressure of the plurality of pressure zones and obtaining a second output pressure of the plurality of pressure zones during pressure adjustment comprises:
attaching a pressure sensing sheet to the lower surface of the grinding head, and obtaining the first output pressure and the second output pressure of each pressure partition through simulated grinding;
the adjusting the initial input pressure of the plurality of pressure partitions specifically includes:
adjusting the initial input pressures of the plurality of pressure zones in accordance with the adjustment direction indicated by the adjustment ratio until the change rate of the second output pressure relative to the first output pressure is in accordance with the adjustment ratio, and terminating the adjustment;
and grinding the product by adopting the input pressure of the pressure subareas obtained when the adjustment is finished as the target input pressure.
10. The apparatus as claimed in claim 9, wherein the pressure-sensitive sheet comprises a substrate and a pressure-sensitive module disposed on a back surface of the substrate, the pressure-sensitive module is provided with a plurality of pressure-sensitive cells, and each pressure zone has at least one pressure-sensitive cell in a vertical projection area.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211157603.3A CN115454158A (en) | 2022-09-22 | 2022-09-22 | Device and method for adjusting and controlling grinding pressure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115890475A (en) * | 2023-02-14 | 2023-04-04 | 广州粤芯半导体技术有限公司 | Pressure calibration method, equipment, device and medium |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115890475A (en) * | 2023-02-14 | 2023-04-04 | 广州粤芯半导体技术有限公司 | Pressure calibration method, equipment, device and medium |
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