Polishing control system and final polishing equipment comprising polishing control system

Abstract

The present invention relates to a polishing control system capable of actively controlling a change in edge flatness (ESFQD) by way of lapse of the service life of a polishing pad, and more particularly, to a polishing control system comprising: a plurality of slurry storage sections for storing slurry; a plurality of slurry solutions having different alkaline solution composition ratios are stored in the plurality of slurry storage parts according to the composition ratios of the alkaline solutions; a memory in which first data on the wafer edge polishing amount according to the lapse of the service life of the polishing pad and second data on the wafer edge polishing amount according to the composition ratio of the alkaline solution contained in the slurry solution stored in the slurry storage part are stored; and a slurry supply part for supplying the slurry solution stored in the slurry storage part to a polishing table of the final polishing equipment based on the first data and the second data stored in the memory.

Description

Technical Field

[0001] The present disclosure relates to a polishing control system, and more particularly, to a polishing control system configured to actively control changes in edge flatness (ESFQD) during the life time of a polishing pad. Background Art

[0002] Figure 1A is a graph showing the quality change of "ESFQD difference (Delta ESFQD)" during the service life of the pad, and Figure 1B is a graph showing the change in thickness of a polishing pad during the useful life of the pad.

[0003] Generally, as the pad life of the polishing pad increases, the thickness of the polishing pad decreases. However, the head down position of the polishing head remains constant.

[0004] Therefore, when polishing a polishing pad in a relatively thin state, compared with polishing a polishing pad in a relatively thick state, the value of the negative ESFQD difference increases due to the exposure of the edge area of ​​the polished wafer, resulting in deterioration of ESFQD (edge ​​flatness).

[0005] In this case, the ESFQD difference is a value obtained by subtracting the edge flatness before polishing from the edge flatness (ESFQD) after single-side polishing of the wafer. A larger negative (-) value indicates a larger edge rolloff. Summary of the Invention Technical issues

[0006] One aspect of the present disclosure is to provide a polishing control system configured to actively control edge flatness (ESFQD) during the service life of a polishing pad by supplying a slurry solution having different concentrations of an alkaline solution.

[0007] Aspects to be achieved by the present disclosure are not limited to the above-mentioned aspects, and other aspects not mentioned herein will be clearly understood by those skilled in the art from the following description. Technical Solution

[0008] The present disclosure discloses a polishing control system for achieving the above-mentioned aspects, which is applicable to final polishing equipment and includes: a plurality of slurry storage sections, which are configured to store a plurality of slurry solutions having different concentrations of alkaline solutions according to the concentration of the alkaline solutions; a memory, which is configured to store first data on the polishing amount at the edge area of ​​the wafer during the life time of the polishing pad and second data on the polishing amount at the edge area of ​​the wafer, depending on the concentration of the alkaline solution contained in the slurry solutions stored in the slurry storage sections; and a slurry supply section, which is configured to supply the slurry solution stored in the slurry storage sections to the polishing table of the final polishing equipment based on the first data and the second data stored in the memory.

[0009] Additionally, the slurry solution may include silica, ammonium hydroxide, water, and a polymer.

[0010] Furthermore, the edge region may be divided into segments in length units in the diameter direction of the wafer.

[0011] In addition, the second data may further include data about the polishing amount at the edge area of ​​the wafer based on at least one of thickness information of the guide ring relative to the wafer, thickness information of the non-woven fabric, thickness information of the nap layer, polishing pressure information, or polishing time information.

[0012] The polishing table may include first to third polishing tables, the slurry storage portion may include first to third slurry storage portions, the first to third slurry storage portions being configured to store slurries of first to third samples having different compositions, and each of the first to third samples may include silicon dioxide (SiO2), ammonium hydroxide (NH4OH), water (H2O), and a water-soluble polymer. The first to third samples may have the same weight percentage of silicon dioxide and the water-soluble polymer and different weight percentages of ammonium hydroxide and water.

[0013] Among the first to third samples, the third sample may have the highest weight percentage of ammonium hydroxide, and the first sample may have the highest weight percentage of water.

[0014] In terms of the ESFQD difference after polishing the edge region of the wafer using the first to third samples, the first sample may have a negative value, and the second and third samples may have positive values, with the third sample having the highest value. The ESFQD difference may be a value obtained by subtracting the edge flatness (ESFQD) before polishing from the edge flatness after single-side polishing of the wafer.

[0015] When single-side polishing is performed on an edge using the slurries of the first to third samples, the first sample may exhibit the largest edge rolloff.

[0016] A wafer having an ESFQD difference value=0 may be obtained by polishing the wafer using the slurry of the first sample for the first 50% of the polishing time and using the slurry of the third sample for the remaining 50% of the polishing time.

[0017] A wafer having an ESFQD difference of 5 may be obtained by polishing the wafer using the slurry of the first sample for the first 26% of the polishing time and using the slurry of the third sample for the remaining 74% of the polishing time.

[0018] A wafer having an ESFQD difference value = -5 may be obtained by polishing the wafer using the slurry of the first sample for the first 70% of the polishing time and using the slurry of the third sample for the remaining 30% of the polishing time.

[0019] Furthermore, a final polishing equipment including the above-mentioned polishing control system is provided.

[0020] Aspects of the present disclosure are only some of the exemplary embodiments of the present disclosure, and those skilled in the art can derive and understand various embodiments reflecting the technical features of the present disclosure based on the detailed description of the present disclosure described below. Beneficial effects

[0021] The polishing control system of the present disclosure described above has the following effects.

[0022] First, the change in edge flatness (ESFQD) can be actively controlled during the life of the polishing pad, thereby making it possible to provide products that meet customer requirements.

[0023] Furthermore, the ESFQDs of the wafer can be controlled by adjusting the concentration of the alkaline solution contained in the slurry solution. Therefore, when using multiple slurry solutions with different alkaline solution concentrations, the same polishing equipment can be used to produce products with different edge flatness.

[0024] In addition, active control of ESFQD can be achieved more accurately using data about the polishing amount at the edge area of ​​the wafer based on at least one of thickness information of the guide ring relative to the wafer, thickness information of the non-woven fabric, thickness information of the nap layer, polishing pressure information, or polishing time information.

[0025] Effects achievable through the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned herein will be clearly understood by those skilled in the art from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A and Figure 1Bis a graph showing the quality change of "ESFQD difference" and the thickness change of the polishing pad during the service life of the pad,

[0027] Figure 2 is a conceptual diagram showing a polishing control system according to the present disclosure and a final polishing equipment including the polishing control system,

[0028] Figure 3A and Figure 3B is a diagram conceptually illustrating a change in wafer polishing position according to a change in the thickness of the polishing pad, and

[0029] Figure 4 is a graph showing a polishing profile at a wafer edge region according to the present disclosure, the polishing profile indicating an edge roll off control state according to the concentration of an alkaline solution contained in a slurry solution. DETAILED DESCRIPTION

[0030] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown.

[0031] In the accompanying drawings, for clarity and convenience of description, elements are enlarged, omitted or schematically shown. In addition, the size of an element does not indicate the actual size of the element. When possible, the same reference numerals will be used throughout the drawings to indicate the same parts.

[0032] Figure 2 is a conceptual diagram illustrating a polishing control system according to the present disclosure and final polishing equipment including the polishing control system. Figure 3A and Figure 3B is a view showing a polishing profile at a wafer edge region according to the present disclosure, the polishing profile indicating an edge roll off control state according to the concentration of an alkaline solution contained in a slurry solution. Figure 4 This is a graph conceptually showing changes in the wafer polishing position according to changes in the thickness of the polishing pad.

[0033] First refer to Figure 2 The polishing control system 10 according to the present disclosure is applied to a final polishing (FP) equipment 20 and may include a slurry storage part 11 , a memory 12 , and a slurry supply part 13 .

[0034] Polishing slurry supplied during wafer polishing may be stored in the slurry storage portion 11. The slurry storage portion 11 according to the present disclosure may include a plurality of tanks in which a plurality of slurries are stored. In each slurry tank, a plurality of slurry solutions having different alkaline solution concentrations may be stored.

[0035] As an example, the slurry solution may include silicon dioxide (SiO2), ammonium hydroxide (NH4OH), water (H2O), and a polymer. The weight percentages of silicon dioxide and the polymer may be fixed, and the weight percentages of ammonium hydroxide and water as the alkaline solution may be varied, thereby making it possible to prepare slurry solutions with different alkali concentrations. The prepared slurry solutions with different alkali concentrations may be stored in respective slurry tanks (hereinafter collectively referred to as "slurry storage units").

[0036] The reason for configuring the system in this way is as follows. In single-sided polishing, slurry is supplied from the peripheral area of ​​the head and delivered to the inner area of ​​the head (the inner area of ​​the wafer) by the rotation of the pressure plate. As the alkali concentration (the amount of ammonium hydroxide) in the slurry increases, the dispersibility between silica and polymer increases, thereby reducing the number of silica-polymer aggregates (coarse particles) and allowing the slurry to effectively penetrate into the center area of ​​the wafer during polishing. Conversely, as the alkali concentration decreases, the number of coarse particles increases, preventing the slurry from evenly penetrating the center area of ​​the wafer and causing the slurry to accumulate on the edge area of ​​the wafer, thereby increasing the polishing rate at the peripheral portion of the wafer.

[0037] That is, in the case of high alkalinity slurry, dispersibility increases, thereby reducing the aggregation between the polymer in the slurry and the polishing particles, which leads to a decrease in the number of coarse particles. In the case of low alkalinity slurry, the opposite effect occurs, resulting in an increase in the number of coarse particles.

[0038] The memory 12 may store first data on a polishing amount at an edge region of a wafer during a life time of the polishing pad and second data on a polishing amount at an edge region of the wafer depending on a concentration of an alkaline solution contained in the slurry solution stored in the slurry storage part 11.

[0039] The background section has already introduced the polishing amount at the edge region of the wafer, i.e., edge flatness (ESFQD), over the service life of the polishing pad. The edge polishing flatness achieved by the polishing pad degrades over time. Therefore, using the above-mentioned slurry solution with an adjusted alkali concentration can minimize the degradation of polishing flatness.

[0040] The slurry supply unit 13 may be connected to the memory 12 and the slurry storage unit 11 to supply the slurry solution stored in the slurry storage unit 11 to the polishing table of the final polishing equipment 20 based on the first data and the second data. To this end, the slurry supply unit 13 and the memory 12 may be communicatively connected to each other, or the slurry supply unit 13 and the memory 12 may be configured as a single module.

[0041] A pipe 13-1 may be installed between a polishing table (not marked) provided on the left side of the final polishing equipment 20 and the slurry storage unit 11. In addition, although not shown, a delivery pump and an on-off valve may be connected to the pipe 13-1. Figure 2 , the piping 13-1 can be connected to the slurry storage unit 11 and the first and second polishing tables of the final polishing equipment 20. Therefore, the slurry supply unit 13 can process the first and second data received from the memory 12 and can control the delivery pump and the switching valve to supply the slurry stored in the slurry storage unit 11 to the polishing tables. Furthermore, the slurry supply unit 13 can be configured to control the supply amount, supply time, and supply amount of the slurry over time.

[0042] At the same time, in order to more accurately control the edge flatness, the second data may further include factors that may affect the edge flatness of the wafer during wafer polishing. The second data may further include data on the polishing amount at the edge region of the wafer based on at least one of, for example, thickness information of the guide ring relative to the wafer, thickness information of the nonwoven fabric of the polishing pad, thickness information of the nap layer of the polishing pad, polishing pressure information, or polishing time information.

[0043] Figure 3A The polishing state in the early stage of the service life of the polishing pad is conceptually shown, and Figure 3B The polishing state at the latter stage of the polishing pad's service life is conceptually shown.

[0044] As shown in the figure, the polishing pad for final polishing may include a lower nonwoven fabric layer 2 and an upper nap (NAP) layer 3. A wafer 4 may be placed on the nap layer 3, and a guide ring 1 may prevent the wafer 4 from escaping.

[0045] In this case, as the final polishing process progresses, the reduction in the thickness of the polishing pad can be detected based on the state of compression between the guide ring 1 and the fleece layer 3. Specifically, the thickness of the fleece layer 3 of the polishing pad decreases in the later stages compared to the earlier stages, resulting in a decrease in the contact force between the polishing pad and the polishing head 5. Consequently, the polishing amount at the edge of the wafer 4 may decrease in the later stages compared to the earlier stages. Therefore, by adjusting the slurry supply amount and supply timing while supplying slurries with different alkali concentrations, the edge flatness of the wafer 4 can be actively controlled.

[0046] At the same time, the edge region of the wafer 4 may be divided into segments in length units in the diameter direction of the wafer, which may follow standards known in the art.

[0047] Hereinafter, embodiments of the present disclosure will be described.

[0048] First, the first data may vary depending on the specifications of the final polishing equipment, and thus may be generated based on results obtained by operating the corresponding type of final polishing equipment.

[0049] Next, to generate the second data, slurry samples may be prepared by varying the weight percentages of ammonium hydroxide and water as follows:

[0050] Sample #1) SiO2 9%, NH4OH 3%, H2O 87%, polymer 1%;

[0051] Sample #2) SiO2 9%, NH4OH 4.5%, H2O 85.5%, polymer 1%;

[0052] Sample #3) SiO2 9%, NH4OH 6%, H2O 84%, polymer 1%.

[0053] The sample is a slurry solution using ammonium hydroxide (NH4OH) at pH 10.6 as an alkaline base, a silica primary size of 35 nm, and a water-soluble polymer having a molecular weight of 1,000,000. These are shown in Table 1 below.

[0054] [Table 1]

[0055] Table 1 above shows the wafer edge roll-off values ​​measured at each alkali concentration.

[0056] Figure 4 The polishing profile of the wafer outer peripheral portion according to the wafer position (mm) in the first step, the second step, and the third step were obtained by applying a pressure of 12 kPa for a polishing time of 150 seconds in the early stage of a Swede type polishing pad having a nap hardness of 20. These results are shown in Table 2 below. Figure 4 , the polishing amount (removal amount) represented by the vertical axis can be understood as increasing in the upward direction.

[0057] [Table 2]

[0058] Table 2 above shows the results obtained in the early stages of the polishing pad's life. It can be understood that the alkali concentration of sample #2 is 50% higher than that of sample #1, and the alkali concentration of sample #3 is 100% higher than that of sample #1.

[0059] Therefore, when it is desired to obtain "ESFQD difference = 0" to maintain the level of "input ESFQD",

[0060] Polishing can be performed using sample #1 for 50% of the total polishing time and using sample #3 for the remaining 50% of the total polishing time. When it is desired to obtain an "ESFQD difference = 5", polishing can be performed using sample #1 for 26% of the total polishing time and using sample #3 for the remaining 74% of the total polishing time. When it is desired to obtain an "ESFQD difference = -5", polishing can be performed using sample #1 for 70% of the total polishing time and using sample #3 for the remaining 30% of the total polishing time. On the other hand, when it is desired to obtain an "ESFQD difference = 5" at the end of the life of the polishing pad, polishing can be performed using only sample #3 for 2.1 times the duration.

[0061] As a result, it can be seen that edge roll-off control can be achieved by adjusting the concentration of the alkali (NH 4 OH) contained in the slurry.

[0062] like Figure 2 As shown, the polishing control system 10 can be applied to and constitute a final polishing equipment 20 .

[0063] That is, the final polishing equipment 20 performs polishing using three polishing stations (step 1, step 2, and step 3) in the polishing apparatus. In step 3, which corresponds to the final step of polishing, a mild slurry with a low polishing rate focused on defect control can be used for polishing, and thus, flatness may not be affected. Flatness can be controlled in the first and second polishing stations by using a slurry with a relatively high polishing rate.

[0064] Therefore, when it is desired to produce a wafer with a "target ESFQD" in the negative (-) direction in the early stage of the polishing pad's life,

[0065] The polishing recipe may be set so that the usage time of sample #3 is shorter than that of sample #1.

[0066] Furthermore, when it is desired to produce wafers with a "target ESFQD" of "0" or in the positive (+) direction at a later stage of the polishing pad's life,

[0067] The recipe may be set up so that sample #3 lasts longer than sample #1.

[0068] Furthermore, when it is desired to achieve a uniform "ESFQD difference" value throughout the early, middle and late stages of the polishing pad's life,

[0069] The "ESFQD Difference" value can be calculated based on the "ESFQD Difference" correlation and the use of Sample #1 and Sample #3 over the life of the polishing pad, and can be controlled in real time based on the calculated value. Therefore, it is possible to actively control the "ESFQD Difference" value at each stage of the polishing pad's life.

[0070] The features, structures, and effects described in connection with the above embodiments are incorporated into at least one embodiment of the present disclosure, but are not limited to one embodiment. In addition, the features, structures, and effects illustrated in connection with each embodiment can be implemented in other embodiments by combining or modifying them by those skilled in the art. Therefore, the content related to such combinations and modifications should be interpreted as falling within the scope of the present disclosure. Industrial Applicability

[0071] The polishing control system and the final polishing equipment including the polishing control system can be used to improve the edge flatness of wafers.

Claims

1. A polishing control system suitable for final polishing equipment, the polishing control system comprising: a plurality of slurry storage parts configured to store a plurality of slurry solutions having different concentrations of the alkaline solution, respectively, according to the concentration of the alkaline solution; a memory configured to store first data on a polishing amount at an edge region of a wafer during a life time of a polishing pad and second data on a polishing amount at the edge region of the wafer, depending on a concentration of the alkaline solution contained in the slurry solution stored in the slurry storage portion; as well as A slurry supply portion is configured to supply the slurry solution stored in the slurry storage portion to the polishing table of the final polishing equipment based on the first data and the second data stored in the memory.

2. The polishing control system according to claim 1, wherein: The slurry solution includes silica, ammonium hydroxide, water and a polymer.

3. The polishing control system according to claim 1, wherein: The second data further includes data on a polishing amount at the edge region of the wafer based on at least one of thickness information of a guide ring relative to a thickness of the wafer, thickness information of a nonwoven fabric, thickness information of a nap layer, polishing pressure information, or polishing time information.

4. The polishing control system according to claim 1, wherein: The polishing stage includes first to third polishing stages, the slurry storage portion includes first to third slurry storage portions configured to store slurries of first to third samples having different compositions, and Each of the first to third samples includes silicon dioxide (SiO2), ammonium hydroxide (NH4OH), water (H2O) and a water-soluble polymer, and the first to third samples have the same weight percentage of silicon dioxide and the water-soluble polymer and different weight percentages of ammonium hydroxide and water.

5. The polishing control system according to claim 4, wherein: Among the first to third samples, the third sample had the highest weight percentage of ammonium hydroxide, and the first sample had the highest weight percentage of water.

6. The polishing control system according to claim 5, wherein: In terms of the ESFQD difference after polishing the edge area of ​​the wafer using the first to third samples, the first sample has a negative value, and the second sample and the third sample have positive values, wherein the third sample has the highest value, and the ESFQD difference is a value obtained by subtracting the edge flatness before polishing from the edge flatness (ESFQD) after single-side polishing of the wafer.

7. The polishing control system according to claim 6, wherein: When single-side polishing was performed on the edge using the slurries of the first to third samples, the first sample showed the largest edge roll off.

8. The polishing control system according to claim 6, wherein: The wafer having an ESFQD difference=0 was obtained by polishing the wafer using the slurry of the first sample for the first 50% of the polishing time and using the slurry of the third sample for the remaining 50% of the polishing time.

9. The polishing control system according to claim 6, wherein: The wafer having an ESFQD difference of 5 was obtained by polishing the wafer using the slurry of the first sample for the first 26% of the polishing time and using the slurry of the third sample for the remaining 74% of the polishing time.

10. The polishing control system according to claim 6, wherein: The wafer having an ESFQD difference value = -5 was obtained by polishing the wafer using the slurry of the first sample for the first 70% of the polishing time and using the slurry of the third sample for the remaining 30% of the polishing time.

11. A final polishing equipment comprising the polishing control system according to any one of claims 1 to 10.

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