NL1010252C2 - Retaining ring for use in a chemical mechanical polishing machine and manufacturing process using it. - Google Patents

Description

LOCKWASHER FOR USE IN A CHEMICAL MECHANICAL POLISHER AND MANUFACTURING PROCESS USING 5

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to semiconductor fabrication technologies, and to an improved retaining ring structure used on the polishing head of a chemical mechanical polishing (CMP) machine to secure a semiconductor wafer in position. CMP process is running. More particularly, the present invention relates to a retaining ring for use in a chemical mechanical polishing machine, comprising a plurality of slurry passages extending from an inner surface to an outer surface of the retaining ring.

2. Description of the Prior Art Such a retaining ring is known from US patents US-A-5,695,392 and US-A-5,749,771.

In semiconductor fabrication, the chemical mechanical polishing (CMP) technique is widely used for the global planarization of semiconductor wafers used for integrated circuit fabrication with VLSI (very-large-scale integration) and ULSI (ultra-large scale integration).

Figures 1A and 1B are diagrams showing a conventional CMP machine. The CMP machine includes a polishing table 10 on which a polishing contact pad 12 is layered, a polishing head 14 to hold a semiconductor wafer 16 in position, and a nozzle 18 for feeding a mass of slurry to the semiconductor wafer 16 during the CMP -process.

Figure 1C shows a respective view of the structure within the polishing head 14. As shown, the polishing head 14 includes an air pressure means 20 which supplies air pressure to a wafer loading device 22 used to hold the wafer 16. In addition, a retaining ring 24 is mounted around the loading device 22 and the wafer, which can lock the wafer 16 in a fixed position during the CMP process. In addition, a pad surface (not shown) is placed between the wafer 16 and the loading device 22.

Figures 2A-2B show a conventional structure for the retaining ring 24. Due to the retaining ring structure of Figures 2A-2B, the polishing slurry is fed under the polishing head 14, that is, over the surface of a wafer to be polished. However, without a suitable conduit or passage of the locking head, the slurry is not uniformly distributed over the surface of the wafer. It has been found that the slurry cannot circulate smoothly over the wafer surface. Therefore, disadvantages such as a large wafer edge exclusion area, a low waste removal rate, an inefficient use of the slurry, and a reduced life of the pad surface are caused. The resulting surface flatness of the wafer after undergoing a CMP process using the retaining ring of Figures 2A-2B is shown in Figure 3. The graph of Figure 3 shows the thickness of the wafer relative to the various points 15 of a straight line passing through the center of rotation of the wafer. The graphical representation shown in Figure 3 shows that the flatness is not entirely satisfactory. The standard deviation of the thickness data is approximately 5.06%.

SUMMARY OF THE INVENTION

20

It is therefore an object of the present invention to provide a new circlip for use on the polishing head of a CMP machine.

This object is achieved with a retaining ring of the type defined in the preamble, the retaining ring further comprising at least one circular path crossing the slurry passages between an inner perimeter and an outer perimeter of the retaining ring.

The new circlip in the CMP machine allows the supplied slurry to be distributed more uniformly across the surface of a wafer. Therefore, the above-mentioned problems arising from using the conventional CMP machine, such as a large wafer edge exclusion area, a low waste removal rate, an inefficient use of the slurry, and a reduced life of the pad surface, are solved.

In accordance with the above and other objects of the present invention, a retaining ring for use on the polishing head of a CMP machine is provided. The retaining ring includes a plurality of slurry passages formed at the bottom edge of the retaining ring. The slurry passages are substantially equidistant from each other, and each of the slurry passages is disposed radially so as to form a sharp angle of incidence to the slurry exterior of the lock ring when the lock ring rotates rapidly.

In accordance with a further embodiment of the invention, a retaining ring is formed with a plurality of straight grooves equally spaced around the bottom of the retaining ring. Each of the straight grooves is inclined radially in such a way that it forms a sharp angle of incidence to the slurry on the outside of the snap ring when the snap ring rotates rapidly.

The location of the straight grooves equidistant from each other causes the slurry to be drawn into the interior of the retaining ring from all radial directions, whereby the slurry can be uniformly distributed over the wafer retained on the inside of the retaining ring. Furthermore, the provision of the round path allows the slurry to be buffered and circulated herein, allowing those wafer edge portions located close to the inner ends of the straight grooves to receive a buffered stream of slurry.

In yet a further embodiment, the slurry passages are designed with a gradually widening slurry path from an inlet to an outlet thereof, a diffusion angle between 0 ° to 10 °, and an incidence angle φι calculated from the equation : x sin ©, = - 1 1 25 where x is the minimum distance between a tangent of an inlet point and a tangent of an outlet point, and 1 is a path length of each of the slurry passages. It is another object of the invention to provide a wafer manufacturing process. The wafer is planarized by a CMP method using the CMP machine with a new retaining ring to obtain much better flatness.

A manufacturing process is also provided to achieve the objects of the invention. To planarize a wafer having a deposition layer thereon, the 1010252 4 wafer is placed within a polishing head with the deposition layer facing down to the polishing table. The wafer is secured within the polishing head by a retaining ring, and the retaining ring includes a plurality of slurry passages. A slurry is fed from a slurry feeder through the retaining ring to be evenly distributed over the deposition layer. The polishing sludge rotates and the polishing head rotates rapidly, and a manufacturing process is also provided to achieve the object of the invention.

In another embodiment, a chemical mechanical process is provided. A deposition layer is formed on a wafer. A chemical mechanical process is performed on the deposition layer using a chemical mechanical polishing machine with a retaining ring that has a plurality of slurry passages at the bottom thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood by reading the following detailed description of the preferred embodiments, with reference to the accompanying drawings.

Figure 1A is a schematic top view of a CMP machine for performing a CMP process on a semiconductor wafer; Figure 1B is a schematic cross section of the CMP machine of Figure 1A;

Figure 1C is a cross-sectional view showing a detailed inner structure of the polishing head used on the CMP machine of Figures 1A and 1B;

Figure 2A is a schematic top plan view of a conventional retaining ring used on the polishing head of Figure 1C;

Figure 2B is a schematic bottom view of the conventional retaining ring of Figure 2A;

Figure 3 is a graph showing the resulting flatness of the semiconductor wafer after undergoing a CMP process using the conventional retaining ring of Figures 2A-2B;

Figure 4A is a schematic top view of a first embodiment of the locking ring according to the invention;

Figure 4B is a schematic bottom view of the retaining ring of Figure 4A: 1010252 5

Figure 5A is a schematic top view of a second embodiment of the locking ring according to the invention;

Figure 5B is a schematic top plan view of the retaining ring of Figure 5A;

Figure 6 is a graph showing the resulting flatness of the semiconductor wafer after undergoing a CMP process using the lock washer of Figures 4A-4B;

Figure 7 is a graph showing the resulting flatness of the semiconductor wafer after undergoing a CMP process using the lock washer of Figures 4A-4B; Figures 8A and 8B are a top view and a side view of a retaining ring in a third embodiment of the invention;

Figure 8C is a schematic cross section of the slurry passageway;

Figures 9A through 9D show the mechanism of the slurry flow;

Figure 10 is a schematic top view of a fourth embodiment of the locking ring according to the invention;

Figures 11A through 11B show cross sections of the process for planarizing a deposition layer on a wafer;

Figures 12A through 12B are cross sections showing a reset etching process; and Figures 13A through 13D are cross-sectional views showing a method of fabricating a shallow trench insulation using the chemical mechanical machine provided in the invention.

DETAILED DESCRIPTION OF

25 PREFERRED EMBODIMENTS

In accordance with the invention, an improved structure of a retaining ring is provided. The improved structure of the retaining ring allows the slurry supplied for polishing the wafer to be evenly distributed over the wafer.

A first embodiment of the invention is described below with reference to Figures 4A-4B.

First embodiment

Figure 4A is a schematic top view of the retaining ring 40 in the first 1010252 embodiment of the invention, and Figure 4B is a schematic bottom view of the retaining ring 40 shown in Figure 4A. The inner diameter of the circlip 40 ranges from 4 inches to 12 inches, or even larger than 12 inches. However, since the retaining ring 40 serves to secure a semiconductor wafer during the CMP process, the actual inner diameter of the retaining ring 40 depends on the size of the wafer to be polished. As shown in Figure 4B, the retaining ring 40 is formed with a plurality of slurry paths, passages or conduits 42. The slurry passages 42 may be formed as grooves under the retaining ring, channels or tubes through the retaining rings, or recesses in another shape. In this embodiment straight grooves are used which are spaced at least approximately equal angular intervals around the retaining ring 40. Each of these slurry passages 42 is angled with respect to the radius such that its outer end brings its inner end to angular position with respect to the rotation direction of the retaining ring 40. While a polishing process is being performed, the retaining ring 40 rotates rapidly with a speed as required, and these slurry passages 42 are oriented with a sharp angle of incidence to the slurry fed from outside the retaining ring 40. Thus, the slurry flows smoothly over the surface of the wafer within the retaining ring 40 through the feed. via the retaining ring 40 using the slurry passages 42. For example, in the case of Figure 4B, the orientation of the straight grooves 42 shows that the retaining ring 40 rotates rapidly in a counterclockwise direction. It will be appreciated that those skilled in the art could arrange the slurry passages 42 in a different manner so that the retaining ring 40 would rotate clockwise during polishing. In this embodiment, each of the slurry passages 42 has a width of 0.05-0.3mm (millimeter) and a depth of 2 ~ 4mm. The actual width and depth of these slurry passages could be different, according to the specific requirements for the polishing process. The manner of equidistantly spacing the sluny passages 42 allows the slurry to be drawn into the retaining ring 40 by an substantially equal amount from all radial directions, whereby the slurry is uniformly distributed over the surface of the wafer can be distributed.

The resulting flatness of a wafer after undergoing a CMP process using the retaining ring of Figures 4A-4B is shown in Figures 6 and 7. The flatness is measured in terms of the thickness values along a straight line 101025a 7 passes through the center of the wafer. The graphs of Figures 6 and 7 show that the flatness of the wafer samples is significantly better than the flatness of the wafer shown in Figure 3 using the prior art retaining ring of Figures 2A-2B . The standard deviation of the thickness is 0.92% in the case of Figure 6 and 1.38% in the case of Figure 7, both of which are significantly better than the standard deviation of 5.06% in the case of Figure 3. Since however, as shown in Figure 7, the edge portions of the wafer near the inner ends of the slurry passages 42 would receive the greatest amount of slurry compared to other parts of the wafer, the polishing effect is much more significant than other parts. As a result, the thickness of the edge portions near the slurry passages is significantly less than that of other parts of the wafer.

Second embodiment

Figure 5A is a schematic top view of the second embodiment of the locking ring 50 according to the invention, and Figure 5B is a schematic bottom view of the locking ring 50 shown in Figure 5A.

As shown in Figure 5B, the design of the slurry passages 52 of the retaining ring 50 in this embodiment is identical to the previous embodiment. That is, these slurry passages 52 have a shape of substantially equally spaced straight grooves. Each of these slurry passages 52 is oriented in a similar manner to the previous embodiment and similarly formed with a width of 0.1 mm and a depth of 2 ~ 4 mm. Again, the width and depth of the slurry passages 52 depend on the specific requirements of the polishing process. In the present embodiment, at least one round recessed ring 54, for example a round groove, is formed on the bottom surface of the retaining ring 50 between the outer perimeter and inner perimeter of the retaining ring 50, which intersects all straight grooves 52. The round recessed ring 54 functions as a buffer ring. The slurry drawn in through the sluny passages 52 is partially buffered and circulates in the round recessed ring 54, making those edge portions of the wafer located near the inner ends of the slurry passages 52 only part of the slurry. Therefore, the polishing effect obtained from the previous embodiment, i.e. an even and uniformly planarized surface of the wafer, is obtained without forming thinner edge portions. The round recessed ring 54 has a similar size to the slurry passages 52, that is to say 1010252 8, a width of about 0.05-0.3 mm and a depth of about 2 ~ 4 mm.

The above two embodiments assume a qualitative viewpoint. With the formation of the slurry passages or even with the round buffer groove crossing the slurry passages, a much better planarized effect is achieved. However, in the above embodiments, the parameters such as the detailed shape of the slurry passages, the angle of incidence, that is, the angle between the centerline of the slurry passageway and the tangent, and the diffusion angle have never been discussed. In the following embodiments, a quantitative viewpoint is taken. The parameters that determine the slurry flow are considered.

10 Third embodiment

A schematic top view of a lock washer is shown as Figure 8A. In this embodiment, twelve slurry passages 82 are formed at the bottom of the retaining ring 80. It will be appreciated that those skilled in the art can select a different number of slurry passages according to the specific requirements during certain polishing processes. Consider a circlip 80 with an outer diameter of 25.40 cm and an inner diameter of 22.86 cm, the width of the circlip 80 therefore being 25.40 cm - 22.86 cm = 2.54 cm. The formation of the slurry passages 82 allows the slurry to flow into the retaining ring and be distributed over the surface of the wafer to be polished. As mentioned above, the slurry passages 82 can be in the form of tubes, grooves, channels or pilot holes penetrating the entire width of the retaining ring 80. The central angle between two consecutive (two adjacent) slurry passages 82 is designated θι, and the angle of incidence of each slurry passage 82 is designated φι. The diameter of the inner end of the slurry passageway 82 is assumed to be d2, while the diameter of the outer end is 25d2. Figure 8B shows a schematic side view of the retaining ring 80 with the slurry passages 82 in a form of guide holes.

When drawing a centerline through the midpoints of one slurry passageway 82, a diffusion angle <p2 is defined as the angle between the centerline and one perimeter of the slurry passageway 82.

Figures 9A through 9D illustrate the mechanism of the polishing process using the locking ring 80 shown in Figures 8A through 8C. The polishing table 90 is assumed to rotate at an angular speed ω \ and the distance between the center of the polishing table 90 and the center of the polishing head is 94 7t. In this case, the polishing head 94 rotates rapidly at an angular speed ωι with a radius r2. As shown in Figure 9A, if the angle between Ti and the j-axis is Θ3 and the angle between 72 and the j-axis is θ4, any point on the perimeter of the polishing head 90 rotates at a speed Vh. The speed can therefore be calculated as: 5

Vh = ωλ x (rx + F2) +672 xF2 = (r, <y, cos <93 + r2 <y, cos <94 + r2 ω2 cos ΘΑ) i - (rx ωχ sin θ3 + r2 ωχ sin θ4 + r2 sin2 sin θ4) j = Ai + Bj (1)

Figure 9B shows the movement of the retaining ring 80. It will be understood that the movement of the retaining ring 80 is synchronous with the polishing head 94 shown in Figure 9A.

When it is considered that the slurry passages are formed with their centerline along the direction of the lock washer speed 80, then, based on the above equation, the direction of the speed Vh, i.e. the angle of incidence of the slurry passageway is: 15 ^ = tan "'¥ (2)

For a circlip 80 which has a minimum distance of 1.25 cm between the tangent of the inlet point and the tangent of the outlet point, and a length of the slurry passage 20 of 1, applies: 1.25 sinp, = - (3)

The slurry passageway can therefore be designed according to the parameters derived from the above ratios.

Figure 9C shows a slurry passage with a narrow inlet and a wider outlet. That is, the slurry passage has a larger cross-sectional area of the inner end than of the outer end. With this design, the path of the 1010252 10 slun flow is gradually widened, and the positive pressure gradient and the slump of the slun flow are moderated. The slurry supplied through the slurry passage is therefore larger. As shown in the figure, Pi, Ai and Vj represent the inlet pressure area and cross-sectional area, respectively, the flow rate of the inlet stream flow. In contrast, P2, A2 and V2 represent the inlet pressure area and cross-sectional area, respectively, the flow rate of the slurry stream at the outlet. It is considered that the friction between the slurry and the slurry passage and the gravity of the slurry is negligible and the slurry is incompressible. If the diffusion angle is φ2 and 1 is the passage length 10, the Bemoulli equation can be used by ignoring the vortex of the inlet slant flow, the outlet bar and any vibration present: P + ^ pV2 - P0 = const . (4) 15 where P is the pressure, p is the density and V is the velocity of the flow, and Po is the thrust. By introducing the equation (4), the spring force coefficient of pressure Cp is:

P -P P -P fv V

20 CV = -2-- = 1—2-— = 1 - (5)

Ρο-t p0-p> UJ

From the continuity equation: 25 A1V1 = A2V2 (6)

The spring force coefficient of pressure can be obtained if:

(A V

Cp = \ f (7) \ Λ2) 30 1010252 11

Therefore, the higher Cp is, the greater A1 / A2 is. In addition, the larger the value of A1 / A2, the wider the diffusion angle φ2, and the slurry flow is expected to be smoother. However, if the diffusion angle 92 is increased above 10 °, an effect of flow deflection 91 or a standstill flow rate 93 is induced. In addition, an inverse flow 95 can be caused so that the transverse area is reduced.

From the above explanations, to design the slurry passageway one should consider the following factors: (1) tan φ2, (2) tan φ2 <10 °, and (3) A2 / A1. With a retaining ring 80 having an outer diameter of 25.40 cm and an inner diameter 10 of 22.86 cm, with reference to Figure 8A, the diameter di of the outer cross-sectional area of slurry passage is approximately 1 cm. While the diameter d2 of the inner cross-sectional area of the slurry passageway 82 is about 1.8 cm. The central angle tussen between two adjacent slurry passages 82 is about 30 °, and the diffusion angle van 2 of each slurry pass is about 30 °.

Fourth embodiment

Figure 5A is a schematic top plan view of the fourth embodiment of the retaining ring 100 according to the invention. The design of the slurry passages 102 of the retaining ring 100 in this embodiment is identical to the third embodiment. These slurry passages 102 are in the form of substantially equidistant grooves with a larger cross section in the inner end and a smaller cross section in the outer end, i.e., a larger outlet and a smaller inlet. Each of these slurry passages 102 is oriented and shaped in a similar manner to the previous embodiment. Again, the width and depth of the slurry passages 102 depend on the specific requirements for the polishing process. That is, the dimensions of the slurry passages 102 should be determined by the factors: (1) tan (p2, (2) tanq> 2 <10 °, and (3) A2 / A introduced in the third embodiment. In this embodiment, at least one circular pad 104, for example, a circular groove, tube, channel, or pilot hole is formed on the bottom surface of the retaining ring 100 between the outer perimeter and inner 30 perimeter of the retaining ring 100, which intersect all straight grooves 102. The circular pad 104 functions as a buffer ring The slurry drawn in through the slurry passages 102 is partially buffered and circulates in the circular path 104, making these wafer edge portions adjacent to the inner ends of the 1010252 12 slurry passages 102 only part of the slurry, therefore, the polished effect obtained from the previous embodiment, i.e. an even and uniformly planarized surface of the wafer, is obtained under thinner edge sections. The circular path 104 has a similar dimension to the 5 slurry passages 102.

Fifth embodiment

In semiconductor technology, chemical-mechanical polishing is the only technique that has so far been able to achieve global planarization in the manufacturing process of a very large-scale or ultra-large-scale integrated circuit. The CMP process 10 can be used in many manufacturing processes, for example, to planarize an uneven surface on a semiconductor substrate to promote the subsequent process, for example, to obtain precise alignment in the next photolithographic etching process. Examples for fabricating a semiconductor device using CMP are drawn and described in the next paragraph.

In Figure 11A, a semiconductor substrate 100 having an uneven surface 110 is provided. A deposition layer 120 is formed on the semiconductor substrate 100. The deposition layer 120 is therefore formed with uneven surface due to the uneven surface 110 underlying it. In the present invention, a CMP machine is used which includes the retaining ring with slurry passages. The CMP machine includes a polishing table, a polishing head facing the polishing table, and a slurry feeding device that supplies slurry to the polishing table for polishing. The circlip is mounted on the bottom edge of the polishing head. While the surface of the deposition layer 120 is facing the polishing table, the semiconductor substrate 100 is disposed within the polishing head and is secured by the locking ring. The deposition layer 120 is therefore planarized. It will be understood that with the conventional CMP machine, due to the unevenly distributed slurry, the deposition layer 120 cannot be planarized with a smooth surface as expected. By passing the sluny through the slurry passages of the retaining ring, or even through the round path, the slurry is evenly distributed over the wafer surface, ie, the surface of the deposition layer 120, and a uniformly planarized surface can be obtained as shown in figure 11B.

The CMP process can also be used for back-etching, for example, for forming a contact pin. In Figure 12A is a substrate 200 that has provided an opening 210. A deposition layer 220 is formed on the substrate 200 and fills the opening 210. To form a contact pin within the opening, the deposition layer 220 is then etched back. Very often a CMP process is performed for the etch-back process. Using a CMP machine with the retaining ring introduced in the invention, a contact pin 220A of very high uniformity is formed as shown in Figure 12B.

Another specific and widely used application for the CMP process is the fabrication of a shallow trench insulation. A method of forming a shallow trench insulation is shown in Figures 13A through 13D. In Figure 13A, a contacting surface oxide layer 302 having a thickness of about 100 Å to 150 Å is formed on a substrate 300, preferably a silicon wafer. A mask layer 304, for example, a silicon nitride layer having a thickness of about 1000 Å to 3000 Å, is formed to cover the contacting surface oxide layer 302. After etching through the mask layer 304, the contact patch oxide layer 302, and the substrate 300, a trench 306 is formed with a depth of about 0.5 µm.

In Figure 13B, along side walls of the etched trench 306, a liner oxide layer 308 is formed with a thickness ranging from about 150 Å to 200 Å. An insulating layer 310 is formed to cover the mask layer 304 and fill the trench 306. Preferably, the insulating layer 310 is formed with a thickness of about 9000 A to 11000 A. Typically, compaction usually follows to obtain an improved quality of the structure.

In Figure 13C, using the mask layer 304 as a stop layer, the insulating layer 310 shown in Figure 13B is polished by a CMP process to form an insulating contact pin 310a. Using a conventional CMP machine, since the slurry cannot be fed evenly distributed over the surface of the insulating layer 310, the particles contained in the slurry cause micro-scratches or other defects. With the formation of these micro-scratches and defects, it is likely that a bridging or electrical short-circuit effect will occur in the following process. The yield of products is deteriorating.

According to the invention, a CMP machine is provided which has a locking ring with slurry passages. The substrate 300 is secured within the retaining ring with 1010252 14 slurry passages. During polishing, the insulating layer 310 (Figure 13B) faces down to a polishing contact pad on a polishing table of the CMP machine to form an insulating contact pin 310a as shown in Figure 13C. Since the polishing slurry is supplied evenly and uniformly distributed over the insulating layer 310, the insulating contact pin 310a is formed with a uniform structure without micro-scratches or defects. Using a conventional method, the mask layer 304 is removed to form the shallow trench insulation.

The invention has been described using exemplary preferred embodiments. It will be understood, however, that the scope of the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and similar devices. The scope of the claims should therefore be given the broadest interpretation to cover all modifications and similar devices.

, -. ^ -. 'Ί. Γ * 't ~,' \ ü; u-a

Claims (14)

Retaining ring for use in a chemical mechanical polishing machine, comprising: a plurality of sluny passages extending from an inner surface to an outer surface of the retaining ring, characterized in that the retaining ring (40) further comprises at least one circular pad (54) includes crossing the slurry passages (42) between an inner perimeter and an outer perimeter of the retaining ring. Retaining ring according to claim 1, wherein the slurry passages (42) are at least 10 equidistant from each other. Retaining ring according to claim 1, wherein the sluny passages (42) are inclined radially such that they form an acute angle of incidence with respect to the slurry flow outside the retaining ring (40). Retaining ring as claimed in claim 1, wherein the retaining ring (40) has an inner diameter of about 15 inches. Retaining ring according to claim 1, wherein the retaining ring (40) comprises ten slurry passages (42). Retaining ring according to claim 1, wherein the slurry passages (45) are each formed with a width of 0.05-0.3 mm and a depth of 2-4 mm. Retaining ring according to claim 2, wherein the slurry has a direct path through the slurry passages (42). Retaining ring according to claim 1, wherein the round pad (54) is formed with a width of 0.05-0.3 mm and a depth of 2-4 mm. The circlip of claim 1, wherein each of the slurry passages (42) has a progressively widening slurry path from an inlet to an outlet thereof. Retaining ring according to claim 9, wherein the slurry passages (42) are designed with diffusion angle between 0 ° to 10 °, and an incidence angle φι calculated from the equation: 30 j. X sin ώ, = - 1 1 - ·. v 'r · f) ·· ^ ï 1 * · .- -J ai, where x is the minimum distance between a tangent of an inlet point and a tangent of an outlet point, and 1 is a path length of each of the slurry passages (42) is. Retaining ring according to claim 9, wherein the slurry passages (42) each have a larger cross-sectional area of an inner end than a cross-sectional area of an outer end. A chemical mechanical polishing machine, comprising: a polishing table; a polishing contact pad on the polishing table; a slurry feeder, for feeding slurry to the polishing table for polishing a wafer; a polishing head to place the wafer therein; and a retaining ring according to any one of claims 1 to 11, on the bottom edge of the polishing head to secure the wafer; the wafer being secured by the retaining ring, the surface of which to be polished facing the polishing contact pad. A chemical mechanical polishing process, for planarizing a surface of a wafer, comprising: arranging the wafer within a polishing head, the surface facing down to the polishing table; securing the wafer within the polishing head by a retaining ring according to any one of claims 1 to 11; feeding slurry from a slurry feeder, the slurry being evenly distributed over the deposition layer through the slurry passages of the retaining ring; and rotating the polishing table and quickly rotating the polishing head. A method of fabricating a shallow trench insulation in a substrate, comprising: forming a mask layer on the substrate, the mask layer having an opening exposing part of the substrate; removing a portion of the exposed substrate to form a trench using the mask layer as a mask; forming an insulating layer over the substrate and filling the trench; and using a chemical mechanical polishing machine according to claim 12. 1010252