CN101327575A - grinding head - Google Patents

Abstract

The invention discloses a grinding head which is suitable for a chemical mechanical grinding process. The polishing head includes an inner collar portion and an outer collar portion. The outer ring part is of a ring structure and is connected with the inner ring part. The inner ring part and the outer ring part are of an integrally formed structure. Further, the surface of the outer ring portion and the surface of the inner ring portion have a level difference such that the surface of the outer ring portion is higher than the surface of the inner ring portion. The invention can improve the grinding rate of the edge of the grinding head without using consumables so as to improve the uniformity of the grinding rate, and can obtain better grinding uniformity by applying a grinding head to fix back pressure.

Description

Translated fromChinese

研磨头grinding head

技术领域technical field

本发明有关于一种集成电路装置，特别是有关于一种研磨头。The present invention relates to an integrated circuit device, in particular to a grinding head.

背景技术Background technique

在半导体工艺技术中，化学机械研磨的原理是利用类似磨刀的机械式原理，配合适当的化学助剂(reagent)，将研磨垫(polishing pad)上的晶片表面高低起伏不一的轮廓加以磨平。一般来说，化学机械研磨装置大多使用研磨头抓住晶片，然后把晶片的正面压在供有研浆(slurry)的研磨垫上进行研磨。在化学机械研磨的过程中，由于机械结构上的限制，而使研磨头上的压力无法全面一致，造成部分区域的研磨率会过高或过低。In semiconductor process technology, the principle of chemical mechanical polishing is to use the mechanical principle similar to sharpening a knife, with appropriate chemical additives (reagent), to grind the uneven contour of the wafer surface on the polishing pad. flat. Generally speaking, most chemical mechanical polishing devices use a polishing head to grasp the wafer, and then press the front side of the wafer on a polishing pad provided with slurry for polishing. During the chemical mechanical polishing process, due to the limitation of the mechanical structure, the pressure on the polishing head cannot be fully consistent, resulting in the polishing rate of some areas being too high or too low.

公知技术利用施以不同的背压于研磨头，也就是使用类似气囊(air bag)以浮动式背压的方式来调整压力，改善研磨率不一致的问题。但是，以浮动式背压的方式加压于研磨头容易因为气压的控制不稳定，而导致加压效果不佳。此外，在公知技术中，也有通过于表面平整的研磨头上覆盖载膜(carrierfilm)，并在研磨率较低的位置，例如是研磨头的边缘，于载膜上加垫一块带(tape)来加大压力。然而，加垫于研磨头上的带的厚度必须非常薄，通常为30μm，使得在制造的过程中，带的品质不易控制。因此，上述两种公知技术会因为气压控制不稳定或是由于耗材制造品质的差异，使研磨率均匀性改善的效果有限，无法达到预期的目的。The known technology utilizes applying different back pressures to the grinding head, that is, using a floating back pressure similar to an air bag to adjust the pressure, so as to improve the problem of inconsistency in the grinding rate. However, applying pressure to the grinding head in the form of floating back pressure is likely to result in poor pressurization effect due to unstable control of the air pressure. In addition, in the known technology, there is also a carrier film (carrier film) covered on the grinding head with a flat surface, and a piece of tape (tape) is placed on the carrier film at a position where the grinding rate is low, such as the edge of the grinding head. Come up the pressure. However, the thickness of the belt on the grinding head must be very thin, usually 30 μm, making it difficult to control the quality of the belt during the manufacturing process. Therefore, the above two known techniques have limited effect on improving the uniformity of the grinding rate due to unstable air pressure control or differences in the manufacturing quality of the consumables, and cannot achieve the desired purpose.

发明内容Contents of the invention

本发明所要解决的技术问题提供一种研磨头，不需使用耗材就能提升研磨头边缘的研磨率，以改善研磨率的均匀性。The technical problem to be solved by the present invention is to provide a grinding head, which can increase the grinding rate of the edge of the grinding head without using consumables, so as to improve the uniformity of the grinding rate.

本发明提出一种研磨头，适用于化学机械研磨工艺(chemicalmechanical polishing，CMP)。研磨头包括内圈部与外圈部。外圈部为环状结构，且连接于内圈部。内圈部与外圈部为一体成型的结构。此外，外圈部的表面与内圈部的表面具有段差，使得外圈部的表面高于内圈部的表面。The invention provides a polishing head suitable for chemical mechanical polishing (CMP). The grinding head includes an inner ring part and an outer ring part. The outer ring part is a ring structure and is connected to the inner ring part. The inner ring part and the outer ring part are integrally formed. In addition, the surface of the outer ring portion has a level difference from the surface of the inner ring portion such that the surface of the outer ring portion is higher than the surface of the inner ring portion.

在本发明的一实施例中，上述的段差介于5μm至35μm之间。In an embodiment of the present invention, the aforementioned step difference is between 5 μm and 35 μm.

在本发明的一实施例中，上述的段差为10μm。In an embodiment of the present invention, the aforementioned step difference is 10 μm.

在本发明的一实施例中，上述的内圈部为圆，而外圈部为圆形环。In an embodiment of the present invention, the above-mentioned inner ring part is a circle, and the outer ring part is a circular ring.

在本发明的一实施例中，上述的圆的半径与圆形环的宽度的比介于2∶1至5∶1之间。In an embodiment of the present invention, the ratio of the radius of the circle to the width of the circular ring is between 2:1 and 5:1.

在本发明的一实施例中，上述的圆的半径与圆形环的宽度的比为3∶1。In an embodiment of the present invention, the ratio of the radius of the above-mentioned circle to the width of the circular ring is 3:1.

在本发明的一实施例中，上述的外圈部邻接于内圈部的外缘，且内圈部与外圈部的接面为垂直接面。In an embodiment of the present invention, the above-mentioned outer ring portion is adjacent to the outer edge of the inner ring portion, and a joint surface between the inner ring portion and the outer ring portion is a vertical joint surface.

在本发明的一实施例中，于内圈部与外圈部之间更包括连接环，使内圈部与外圈部相连接。In an embodiment of the present invention, a connecting ring is further included between the inner ring part and the outer ring part to connect the inner ring part and the outer ring part.

在本发明的一实施例中，上述的连接环的表面为斜面。In an embodiment of the present invention, the surface of the above-mentioned connecting ring is a slope.

根据上述方案，本发明相对于现有技术的效果是显著的：According to above-mentioned scheme, the effect of the present invention relative to prior art is remarkable:

本发明的研磨头利用其表面轮廓形成有段差，来调整边缘区域研磨率较低的现象。由于研磨头的外圈部的表面高于内圈部的表面，使得原本研磨率较低的边缘区域的研磨率能够获得提升，以改善研磨率的均匀性。The grinding head of the present invention utilizes the level difference formed in its surface profile to adjust the phenomenon of lower grinding rate in the edge area. Since the surface of the outer ring portion of the grinding head is higher than the surface of the inner ring portion, the grinding rate of the edge region where the grinding rate is originally low can be increased to improve the uniformity of the grinding rate.

此外，本发明的研磨头不需额外使用耗材，如载膜或带，因此可以避免研磨率受到耗材制造品质不一的影响。并可以通过减少耗材的使用，降低研磨头的制作成本。In addition, the grinding head of the present invention does not need to use additional consumables, such as carrier film or belt, so the grinding rate can be avoided from being affected by the manufacturing quality of consumables. And can reduce the production cost of the grinding head by reducing the use of consumables.

再者，利用本发明具有凹凸构形的研磨头来进行晶片的研磨，当施以相同背压于此研磨头时，会在研磨头的外圈部形成较大的压力。因此，能够调整整体的研磨率，而使晶片表面的均匀度可以提升。Furthermore, when using the grinding head with concave-convex configuration of the present invention to grind the wafer, when the same back pressure is applied to the grinding head, a larger pressure will be formed on the outer ring of the grinding head. Therefore, the overall grinding rate can be adjusted, so that the uniformity of the wafer surface can be improved.

附图说明Description of drawings

图1A为依照本发明一实施例所绘示的研磨头的俯视图及沿I-I’线段剖面图的投影关系对照示意图。Fig. 1A is a schematic diagram showing a comparison between a top view of a grinding head and a cross-sectional view along line I-I' according to an embodiment of the present invention.

图1B为依照本发明另一实施例所绘示的研磨头的俯视图及沿I-I’线段剖面图的投影关系对照示意图。Fig. 1B is a schematic diagram showing a top view of a grinding head according to another embodiment of the present invention and a cross-sectional view along the I-I' line segment.

图2为以本发明的研磨头进行化学机械研磨工艺的移除率分布图。FIG. 2 is a distribution diagram of the removal rate of the chemical mechanical polishing process using the polishing head of the present invention.

图3为以公知的覆盖载膜的研磨头进行化学机械研磨工艺的移除率分布图。FIG. 3 is a distribution diagram of the removal rate of a chemical mechanical polishing process using a known polishing head covered with a carrier film.

主要元件符号说明Description of main component symbols

100、200……研磨头  102……内圈部100, 200...Grindinghead 102...Inner ring

104…………外圈部   106……连接环104………Outer ring part 106…Connecting ring

106a………表面      108……接面106a……Surface 108… Junction

D……………段差     W1……半径D…………Segment difference W1……Radius

W2……………宽度W2……………Width

具体实施方式Detailed ways

为让本发明的上述特征和优点能更明显易懂，下文特举较佳实施例，并配合所附图式，作详细说明如下。In order to make the above-mentioned features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

图1A为依照本发明一实施例所绘示的研磨头的俯视图及沿I-I’线段剖面图的投影关系对照示意图。Fig. 1A is a schematic diagram showing a comparison between a top view of a grinding head and a cross-sectional view along line I-I' according to an embodiment of the present invention.

请参照图1A，适用于化学机械研磨工艺的研磨头100例如是一个圆形的结构。研磨头100包括内圈部102以及外圈部104。Referring to FIG. 1A , thepolishing head 100 suitable for the chemical mechanical polishing process is, for example, a circular structure. Thegrinding head 100 includes aninner ring part 102 and anouter ring part 104 .

在本实施例中，内圈部102为实心圆形结构，而外圈部104为圆形环状结构。外圈部104环绕于内圈部102的周围，且外圈部104的内缘与内圈部102的外缘相邻接，使二者之间的接面108为垂直接面。内圈部102与外圈部104为一体成型的结构。也就是说，从俯视的角度来看研磨头100，内圈部102与环状的外圈部104例如是共同构成一个同心圆的结构。In this embodiment, theinner ring part 102 is a solid circular structure, and theouter ring part 104 is a circular ring structure. Theouter ring portion 104 surrounds theinner ring portion 102 , and the inner edge of theouter ring portion 104 is adjacent to the outer edge of theinner ring portion 102 , so that thejoint surface 108 between them is a vertical joint plane. Theinner ring portion 102 and theouter ring portion 104 are integrally formed. That is to say, looking at the polishinghead 100 from a plan view, theinner ring portion 102 and the ring-shapedouter ring portion 104 form a concentric circle, for example.

请参照图1A，在研磨头100的半径截面上，内圈部102的半径W1与外圈部104所占的宽度W2的比例如是介于2∶1至5∶1之间。另一方面，外圈部104的厚度例如是大于内圈部102的厚度，且外圈部104的表面会高于内圈部102的表面，而二者之间的段差D例如是介于5μm至35μm之间。在一实施例中，研磨头100的半径为100mm，内圈部102的半径W1为75mm，外圈部104环状结构的宽度W2则为25mm；而外圈部104表面与内圈部102表面之间的段差D为10μm。Referring to FIG. 1A , on the radius section of thegrinding head 100 , the ratio of the radius W1 of theinner ring portion 102 to the width W2 of theouter ring portion 104 is, for example, between 2:1 and 5:1. On the other hand, the thickness of theouter ring portion 104 is, for example, greater than the thickness of theinner ring portion 102, and the surface of theouter ring portion 104 is higher than the surface of theinner ring portion 102, and the step D between the two is, for example, 5 μm. to 35μm. In one embodiment, the radius of the grindinghead 100 is 100 mm, the radius W1 of theinner ring part 102 is 75 mm, and the width W2 of the annular structure of theouter ring part 104 is 25 mm; The step difference D between them is 10 μm.

图1B为依照本发明另一实施例所绘示的研磨头的俯视图及沿I-I’线段剖面图的投影关系对照示意图。于图1B中，与图1A相同的构件则使用相同的标号并省略其说明。Fig. 1B is a schematic diagram showing a top view of a grinding head according to another embodiment of the present invention and a cross-sectional view along the I-I' line segment. In FIG. 1B , the same components as those in FIG. 1A use the same reference numerals and their descriptions are omitted.

请参照图1B，本发明还提出另一种适用于化学机械研磨工艺的研磨头200。组成研磨头200的基本构件与组成研磨头100的基本构件大致相同，其中主要的差异在于：在研磨头200中，于内圈部102与外圈部104之间更包括连接环106，连接内圈部102与外圈部104之间。连接环106为圆形环状结构，且其内缘与内圈部102邻接，其外缘则与外圈部104邻接。连接环106的表面106a例如是斜面，可以将内圈部102的表面与外圈部104的表面连接起来。值得一提的是，连接环106的数量以及表面构造并不局限于图1B所绘示，只要能够使内圈部102与外圈部104相连接并构成一体成形的结构即可，本发明于此不作特别的限定。Please refer to FIG. 1B , the present invention also proposes another polishinghead 200 suitable for a chemical mechanical polishing process. The basic components that make up the grindinghead 200 are roughly the same as those that make up the grindinghead 100, and the main difference is that in the grindinghead 200, a connectingring 106 is further included between theinner ring part 102 and theouter ring part 104 to connect the inner between thering portion 102 and theouter ring portion 104 . The connectingring 106 is a circular ring structure, and its inner edge is adjacent to theinner ring part 102 , and its outer edge is adjacent to theouter ring part 104 . Thesurface 106 a of theconnection ring 106 is, for example, an inclined surface, which can connect the surface of theinner ring part 102 and the surface of theouter ring part 104 . It is worth mentioning that the number and surface structure of the connectingrings 106 are not limited to those shown in FIG. This is not particularly limited.

请同时参照图1A与图1B，换言之，研磨头100与研磨头200具有凹凸构形，上述的内圈部102即为凹部，外圈部104为凸部。当然，在其它实施例中，研磨头100与研磨头200的凹部与凸部的配置并不局限于上述的内圈部102与外圈部104，于此领域具有通常知识者可视其需求进行调整。Please refer to FIG. 1A and FIG. 1B at the same time. In other words, the grindinghead 100 and the grindinghead 200 have concave-convex configurations, the above-mentionedinner ring portion 102 is a concave portion, and theouter ring portion 104 is a convex portion. Of course, in other embodiments, the configuration of the concave and convex portions of the grindinghead 100 and the grindinghead 200 is not limited to the above-mentionedinner ring portion 102 andouter ring portion 104, and those who have ordinary knowledge in this field can make according to their needs. Adjustment.

承上述，内圈部102与外圈部104的结构为一体成型的构造。因此，研磨头100与研磨头200的形成方法是在具有平整表面的刚体材料(未绘示)上，例如是平面研磨头本体，保留研磨率表现较低的边缘位置，在研磨率较高的内圈位置移除部份刚体材料作为内圈部102。移除刚体材料的方法例如是通过切削或是研磨的方式向下切削研磨，使刚体材料上形成具有段差D的内圈部102与外圈部104。而段差D则是利用控制向下切削或研磨的深度来进行调整。当然，内圈部102的半径W1以及段差D可以经由使用研磨头100与研磨头200进行后续的化学机械研磨工艺，所研磨出来的材料层表面轮廓进行修正，以取得最佳化的条件。此外，移除部份刚体材料的位置并不局限于本实施例中所绘示的内圈部102的形成位置，移除部份刚体材料的区域可以为任何研磨率较高而需调整的区域，于此领域具有通常知识者当可视其需求进行调整。Based on the above, the structures of theinner ring part 102 and theouter ring part 104 are integrally formed. Therefore, the forming method of the grindinghead 100 and the grindinghead 200 is on a rigid body material (not shown) with a flat surface, such as a flat grinding head body, to reserve the edge position where the grinding rate is low, and to keep the edge position where the grinding rate is relatively high. Part of the rigid body material is removed from the position of the inner ring as theinner ring part 102 . The method of removing the rigid body material is, for example, cutting or grinding down to form theinner ring portion 102 and theouter ring portion 104 with a step difference D on the rigid body material. The step difference D is adjusted by controlling the depth of downward cutting or grinding. Certainly, the radius W1 and the level difference D of theinner ring portion 102 can be corrected by using the polishinghead 100 and the polishinghead 200 to perform the subsequent chemical mechanical polishing process, and the surface profile of the ground material layer can be corrected to obtain optimal conditions. In addition, the location where part of the rigid body material is removed is not limited to the formation location of theinner ring portion 102 shown in this embodiment, and the area where part of the rigid body material is removed can be any area where the grinding rate is relatively high and needs to be adjusted , those with ordinary knowledge in this field can adjust it according to their needs.

特别说明的是，在研磨头100与研磨头200中，具有较高表面的外圈部104是配置于公知平面研磨头中研磨率较低的区域。而使用上述的研磨头100或研磨头200进行化学机械研磨工艺，是先以研磨头100或研磨头200将晶片(未绘示)固定于研磨垫(未绘示)上，其中研磨垫上例如是布满研浆。之后，施以固定背压于研磨头100或研磨头200，再利用研磨垫与晶片的相对移动进行研磨步骤。由于研磨头100与研磨头200具有凹凸构形，即使在施加固定背压的情况下，还是可以通过研磨头100与研磨头200表面轮廓的差异来提供晶片不同的压力。进一步而言，构成凸部的外圈部104会提供较大压力于晶片。因此，在进行研磨步骤时，可以使研磨头100与研磨头200边缘的研磨率获得提升，而改善研磨均匀性。In particular, in the grindinghead 100 and the grindinghead 200 , theouter ring portion 104 with a higher surface is disposed in a region with a lower grinding rate in the conventional flat grinding head. And use above-mentionedpolishing head 100 or polishinghead 200 to carry out chemical mechanical polishing process, be to fix wafer (not shown) on the polishing pad (not shown) with polishinghead 100 or polishinghead 200 first, wherein on the polishing pad such as Covered with slurry. After that, a fixed back pressure is applied to the polishinghead 100 or the polishinghead 200 , and then the polishing step is performed by using the relative movement of the polishing pad and the wafer. Since the grindinghead 100 and the grindinghead 200 have concave-convex configurations, even under the condition of applying a fixed back pressure, different pressures on the wafer can be provided by the difference in the surface contours of the grindinghead 100 and the grindinghead 200 . Furthermore, theouter ring portion 104 constituting the convex portion will provide greater pressure on the wafer. Therefore, during the grinding step, the grinding rate of the edges of the grindinghead 100 and the grindinghead 200 can be increased, thereby improving grinding uniformity.

为证实本发明的研磨头确有其功效，以下特举一个实验例来说明本发明的研磨头应用于化学机械研磨工艺时所达到的效果。In order to prove that the grinding head of the present invention is effective, an experimental example is given below to illustrate the effect achieved when the grinding head of the present invention is applied to a chemical mechanical polishing process.

实验例Experimental example

图2是以本发明的研磨头(如图1A所示的研磨头100)进行化学机械研磨工艺的移除率分布图。FIG. 2 is a distribution diagram of the removal rate of the chemical mechanical polishing process performed by the polishing head of the present invention (the polishinghead 100 shown in FIG. 1A ).

请参照图2，当使用本发明的研磨头进行化学机械研磨工艺时，是将晶片固定于本发明的研磨头上，再施加固定的背压于研磨头，使晶片压至研磨垫上以进行研磨步骤。从图2的结果中显示，远离圆心的边缘部份的移除率确实可以有效地提升，且整体研磨率的均匀性也获得改善(研磨均匀度为500A/min)。再者，图2中分别绘示的四次数据分布十分一致，显示本发明的研磨头还可以使研磨率有持续稳定的表现。Please refer to Fig. 2, when using the grinding head of the present invention to carry out chemical mechanical polishing process, be that wafer is fixed on the grinding head of the present invention, apply fixed back pressure to grinding head again, make wafer be pressed on the grinding pad to grind step. The results in Figure 2 show that the removal rate of the edge part away from the center of the circle can be effectively improved, and the uniformity of the overall grinding rate is also improved (the grinding uniformity is 500A/min). Furthermore, the four data distributions shown in FIG. 2 are very consistent, which shows that the grinding head of the present invention can also make the grinding rate have a continuous and stable performance.

比较例comparative example

图3是以公知的覆盖载膜的研磨头进行化学机械研磨工艺的移除率分布图。FIG. 3 is a distribution diagram of the removal rate of a chemical mechanical polishing process performed by a known polishing head covered with a carrier film.

比较例与实验例进行化学机械研磨的方法相似，唯一的差别仅在所使用的研磨头不同。请参照图3，在使用仅覆盖载膜的研磨头进行化学机械研磨时，表面为平面的研磨头会造成部分区域的移除率过高或过低，尤其是远离圆心的边缘部份会发生移除率明显降低的问题，而导致均匀性不佳。The chemical mechanical polishing method of the comparative example is similar to that of the experimental example, and the only difference is the used polishing head. Please refer to Figure 3. When using a polishing head that only covers the carrier film for chemical mechanical polishing, the polishing head with a flat surface will cause the removal rate to be too high or too low in some areas, especially at the edge far away from the center of the circle. The removal rate is significantly reduced, resulting in poor uniformity.

由以上实际测试的结果显示：本发明的研磨头不仅可以提升边缘的研磨率，还可以改善研磨率的均匀性并使研磨率稳定表现。The above actual test results show that the grinding head of the present invention can not only increase the grinding rate of the edge, but also improve the uniformity of the grinding rate and stabilize the grinding rate.

综上所述，本发明于研磨头的内圈部形成凹部，使位于研磨头外圈部作为凸部，再施予研磨头固定背压进行化学机械研磨工艺，可以使原本研磨率较低的边缘通过研磨头的凹凸构形造成压力的改变，而使外圈部研磨率增加，因而可以获得较佳的均匀性。In summary, the present invention forms a concave portion on the inner ring of the grinding head, makes the outer ring of the grinding head a convex portion, and then applies a fixed back pressure to the grinding head to perform a chemical mechanical grinding process, which can make the original grinding rate lower The edge changes the pressure through the concave-convex configuration of the grinding head, which increases the grinding rate of the outer ring, so that better uniformity can be obtained.

另一方面，由于本发明的研磨头采用固定式的刚体结构，而不需额外使用载膜或带等耗材，可以避免耗材的制造品质造成研磨率不稳定。此外，此种一体成型的结构在于工艺参数的最佳化及维护上都较为容易，并能获得较大的工艺裕度(process window)。On the other hand, since the grinding head of the present invention adopts a fixed rigid body structure, it does not need additional consumables such as carrier film or belt, which can avoid the unstable grinding rate caused by the manufacturing quality of consumables. In addition, the integral molding structure is easier to optimize and maintain process parameters, and can obtain a larger process window.

再者，本发明通过改变研磨头表面轮廓的简单手段，即可调整部分区域研磨率，达成较佳均匀性的目的，且不需额外使用耗材，可有助于节省工艺成本。Furthermore, the present invention can adjust the grinding rate in some areas by simply changing the surface profile of the grinding head to achieve better uniformity without using additional consumables, which can help save process costs.

虽然本发明已以较佳实施例揭露如上，然而其并非用以限定本发明，任何所属技术领域中具有通常知识者，在不脱离本发明的精神和范围内，当可作些许的更动与润饰，因此本发明的保护范围当视权利要求书所界定的范围为准。Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and changes without departing from the spirit and scope of the present invention. Modification, therefore, the protection scope of the present invention should be determined by the scope defined in the claims.

Claims (9)

Translated fromChinese

1.一种研磨头，适用于一化学机械研磨工艺，其特征在于，包括：1. A grinding head, suitable for a chemical mechanical grinding process, is characterized in that, comprising:一内圈部；以及an inner ring portion; and一外圈部，该外圈部为环状结构，连接于该内圈部，该内圈部与该外圈部为一体成型，其中该外圈部的表面与该内圈部的表面具有一段差，使该外圈部的表面高于该内圈部的表面。An outer ring part, the outer ring part is a ring structure, connected to the inner ring part, the inner ring part and the outer ring part are integrally formed, wherein the surface of the outer ring part and the surface of the inner ring part have a The level difference makes the surface of the outer ring part higher than the surface of the inner ring part.2.如权利要求1所述的研磨头，其特征在于，该段差介于5μm至35μm之间。2. The grinding head according to claim 1, wherein the step difference is between 5 μm and 35 μm.3.如权利要求2所述的研磨头，其特征在于，该段差为10μm。3. The grinding head according to claim 2, wherein the step difference is 10 μm.4.如权利要求1所述的研磨头，其特征在于，该内圈部为一圆，该外圈部为一圆形环。4. The grinding head as claimed in claim 1, wherein the inner ring portion is a circle, and the outer ring portion is a circular ring.5.如权利要求4所述的研磨头，其特征在于，该圆的半径与该圆形环的宽度的比介于2∶1至5∶1之间。5. The grinding head of claim 4, wherein the ratio of the radius of the circle to the width of the circular ring is between 2:1 and 5:1.6.如权利要求5所述的研磨头，其特征在于，该圆的半径与该圆形环的宽度的比为3∶1。6. The grinding head according to claim 5, wherein the ratio of the radius of the circle to the width of the circular ring is 3:1.7.如权利要求1所述的研磨头，其特征在于，该外圈部邻接于该内圈部的外缘，且该内圈部与该外圈部的接面为垂直接面。7 . The grinding head according to claim 1 , wherein the outer ring portion is adjacent to an outer edge of the inner ring portion, and a joint surface between the inner ring portion and the outer ring portion is a vertical joint surface.8.如权利要求1所述的研磨头，其特征在于，于该内圈部与该外圈部之间更包括一连接环，使该内圈部与该外圈部相连接。8 . The grinding head according to claim 1 , further comprising a connecting ring between the inner ring part and the outer ring part to connect the inner ring part to the outer ring part.9.如权利要求8所述的研磨头，其特征在于，该连接环的表面为斜面。9. The grinding head as claimed in claim 8, wherein the surface of the connecting ring is an inclined plane.

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