KR20090055414A - Wafer pressing apparatus of a polisher - Google Patents

Abstract

A wafer pressing apparatus of a polishing device is provided to apply a polishing process amount to a whole surface of a wafer by uniformly delivering pressure delivered to the wafer to a central part and an edge part of the wafer. A pressure applying unit supplies air pressure to a chamber(140). A pressing unit applies pressure to a wafer by using the air pressure. The pressing unit includes an expanding unit(110) capable of being selectively expanded by the air pressure. A template assembly(150) is adjacent to the expanding unit, and pressurizes the wafer by receiving an expanding force of the expanding unit. A fixing unit(160) fixes an edge part of the expanding unit.

Description

Wafer Pressing Machine of Polishing Machine {Wafer Pressing Apparatus of a Polisher}

The present invention relates to a wafer compaction apparatus of a polishing apparatus. In particular, the present invention relates to a wafer compaction apparatus of a polishing apparatus for improving the flatness of a wafer in a final polishing process of silicon wafer processing for semiconductors.

In recent years, as semiconductor devices have been highly integrated, wiring structures have been multilayered to increase the surface level between unit cells stacked on a semiconductor substrate, or between cell array regions and peripheral circuit regions. Various wafer planarization methods have been proposed to reduce the aforementioned surface steps.

In order to planarize the wafer, polishing is performed by applying pressure to the wafer in the final polishing process, which is the final process of wafer processing. When using a rubber head to pressurize the wafer using pneumatic pressure, the pressure transferred to the workpiece There is an advantage over direct pressure delivery in terms of keeping the constant constant.

1 is a partial cross-sectional view showing a wafer compaction apparatus 10 of a general polishing apparatus.

As shown in FIG. 1, a typical wafer compaction apparatus 10 includes a pneumatic line 12, a chamber 14, an expansion element 11, and a template assembly 15. The chamber 14 is formed into a space enclosed by the expansion element 11 and the back plate 13, and the expansion element 11 is made of rubber, which is generally a flexible material, from the pneumatic line 12. It deforms as the pressure in the chamber 14 increases due to the supplied pressure. In other words, when the pressure in the chamber 14 is increased, the expansion element 11 expands to transmit the pressure P to the template assembly 15. In this case, the template assembly 15 is in close contact with the wafer 1 and the wafer 1. The pressure P is transmitted to (1). The wafer 1, which has received the pressure P, is pressed onto the pad 2, and then the polishing process is performed.

However, in the conventional general wafer pressing device 10, it is difficult to expand at the same pressure because one side of the edge of the expansion element 11 and the template assembly 15 is attached to the fixing element 16 in its structure. This phenomenon can also be confirmed from the distribution of the pressure P applied to the wafer in FIG. 1, which shows that the pressure P of the edge portion is smaller than that of the center portion. This may be a phenomenon due to the constant thickness of the expansion element (11).

Since the pressure of the structural edges of the expansion element 11 and the template assembly 15 is lower than that of the central portion and the other portions, this causes a difference in positional polishing during processing. That is, since the processing amount of the edge portion is smaller than that of other portions, the flatness of the wafer 1 is deteriorated and the quality of the edge portion is deteriorated.

In addition, in order to apply uniform pressure to the wafer 1 to improve flatness, the wafer compaction apparatus 10 should be made larger and the wafer 1 should be placed only at a portion where the pressure P is uniform. In addition to the problem of cost increase, there are many difficulties in that the wafer 1 must be located at the center of the expansion element 11.

The present invention is to provide a wafer compaction apparatus in which the pressure delivered to the wafer during the wafer polishing process is uniformly transmitted without a large difference between the center portion and the edge portion of the wafer so that the amount of polishing processing is constant on the entire surface of the wafer.

An object of the present invention is to provide a wafer compaction apparatus of a polishing apparatus capable of miniaturizing the whole unit by maintaining a constant pressure on the front surface of the wafer so as not to provide an area larger than necessary than the wafer compaction area.

The wafer compaction apparatus of the polishing apparatus according to the present invention includes a chamber, a pressure providing unit for providing air pressure to the chamber, and a pressurizing unit for applying pressure to the wafer using pneumatic pressure, the pressurizing unit including an expansion element. In this case, the expansion element is variable in thickness and selectively expanded by pneumatic pressure.

The wafer compaction apparatus of the polishing apparatus according to the present invention further includes a template assembly and a fixing element for fixing the edge portion of the expansion element, the template assembly receiving the expansion force of the expansion element to press the wafer.

Preferably, the expansion element is made of a flexible material, which is preferably made of rubber.

The shape of the inflation element is thicker at the center than the edge, and the inflation element may be one-time thickened from the edge to the center, or may be multi-stage thickened from the edge to the center, and also from the edge to the center. It may have a shape that gradually thickens toward.

Preferably, the thickness of the central portion of the expansion element is at least 0.9 mm and at most 1.1 mm, and the thickness of the edge portion is at least 0.7 mm and less than 0.9 mm.

The present invention also provides a polishing apparatus including a polishing machine and a wafer compaction apparatus disposed at a position opposite the polishing machine. The wafer compaction apparatus serves to press the wafer into the polishing machine and includes a chamber, a pressure providing unit for providing pneumatic pressure to the chamber, a pressurizing unit for pressurizing the wafer using pneumatic pressure, a template assembly, and a fixing element. The pressurization unit also includes an expansion element, the expansion element having a variable thickness and sensibly expanded by pneumatic pressure. The template assembly is in contact with this inflation element to transfer inflation force from the inflation element to the wafer, and the fixing element secures the edge portion of the inflation element. Preferably, the expansion element is made of rubber and the central portion has a shape thicker than the edge portion.

Preferably, the expansion element of the polishing apparatus may be shaped to be thickened in a single step from the edge portion to the center portion, or may be shaped to be multi-stage thickened from the edge portion to the center portion, and may also be formed from the edge portion to the center portion. It may be a shape that gradually thickening continuously.

When the wafer is pressed using the wafer pressing device of the polishing apparatus according to the present invention, the pressure applied to the wafer is uniformly transmitted without a large difference between the center portion and the edge portion of the wafer, so that the amount of polishing processing over the entire surface of the wafer is increased. Can be constant. Therefore, there is an effect that can improve the flatness of the processed wafer and prevent the degradation of the wafer edge portion.

The wafer compaction apparatus of the polishing apparatus according to the present invention has the advantage that the pressure applied to the front surface of the wafer is kept constant so that the wafer compaction area does not have to be made larger than necessary. Therefore, it is advantageous for miniaturization of the wafer compaction apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. For reference, in the present description, the same numbers refer to substantially the same elements, and may be described by quoting the contents described in other drawings under the above rules, and the contents repeated or deemed apparent to those skilled in the art may be omitted.

2 is a partial cross-sectional view of the wafer compaction apparatus 100 of the polishing apparatus according to the present invention. The wafer compaction apparatus 100 of the present invention largely includes a chamber 140, a pressure providing unit, a pressurizing unit, a template assembly 150, and a fixing element 160. The pressurization unit includes an expansion element 110, which is of variable thickness and is selectively inflated under pressure. Hereinafter, each component will be described in detail.

The chamber 140 is surrounded by the back plate 130, the expansion element 110, and the fixing element 160 to form a closed space. Pneumatic pressure provided from the pressure supply unit is supplied to the chamber 140, the volume of the chamber 140 is changed by the pressure supplied. That is, it expands.

The pressure providing unit is formed of an air pressure line 120 and a back plate 130. The backplate 130 is generally of round cylindrical shape corresponding to the wafer. Pneumatic line 120 is formed through the center of the back plate 130, which is connected to the chamber 140 to transfer the pneumatic pressure to the chamber 140.

The pressurization unit serves to pressurize the wafer 1 by using the pneumatic pressure supplied to the chamber 140, and is composed of an expansion element 110. The expansion element 110 is made of a flexible material, it is expanded by the pressure supplied to the chamber 140 through the pneumatic line 120. In general, the expansion element 110 is made of rubber. The edge portion of the expansion element 110 has a structure attached to the fixing element 160, so that the edge portion is generally disadvantageous to expansion compared to the center portion. In order to overcome this point, the structure of the expansion element 110 has an edge portion that is thinner than the center portion.

Template assembly 150 is in contact with expansion element 110. In addition, the template assembly 150 is in contact with the wafer opposite the surface in contact with the expansion element 110. The template assembly 150 receives the expansion force of the expansion element 110 to apply a pressure (P) to the wafer.

The fixing element 160 is disposed around the back plate 130. The holding element 160 holds the edge of the inflation element 110, so that the inflation element 110 does not escape from the wafer compaction apparatus 100 even when the inflation element 110 is inflated. ) It keeps the pneumatic pressure constant.

Hereinafter, a process of transferring pressure from the pressure providing unit to the wafer via the pressing unit will be described.

Pneumatic is supplied via pneumatic line 120. Since the pneumatic line 120 passes through the back plate 130 to the chamber 140 as described above, the pneumatic pressure supplied from the pneumatic line 120 is injected into the chamber 140. Before the pneumatic pressure is supplied to the chamber 140, the back plate 130 and the expansion element 110 are in close contact with each other by the elasticity of the expansion element 110. As pneumatic pressure begins to be supplied into the chamber 140, the pressure in the chamber 140 rises, which inflates the expansion element 110 away from the backplate 130. The expanded expansion element 110 pressurizes the adjacent template assembly 150 to transmit the pressure P to the template assembly 150. The template assembly 150 receiving the pressure P again pressurizes the wafer 1 positioned opposite to the expansion element 110 to transfer the pressure P to the wafer 1. The pressure P transmitted to the wafer 1 adheres the wafer 1 to the pad 2 so that polishing is performed. The polishing process improves the flatness of the wafer 1 and improves the surface mirroring.

However, the wafer pressing device 100 according to the present invention may transmit a uniform pressure P across the entire surface of the wafer 1 due to the shape of the expansion element 110, unlike the conventional wafer pressing device 10. That is, as can be seen in FIG. 2, when the pressure is transmitted by the conventional general wafer pressing device 10, the pressure P applied to the edge of the wafer 1 and the pressure P applied to the center of the wafer 1 are used. While the difference is relatively large, when using the wafer compaction apparatus 100 according to the present invention, there is a large difference between the pressure P applied to the edge of the wafer 1 and the pressure P applied to the center. You can see that none. This is made possible by making the shape of the expansion element 110 relatively thinner at the edge than at the center.

In more detail with respect to the shape of the expansion element 110, it is appropriate to make the edge portion of the expansion element 110 by about 15% to 25% smaller than the central portion. In other words, the conventional expansion element 11 has the same thickness of the center portion and the edge portion, but the expansion element 110 according to the present invention is thinner the edge portion than the center portion, so that the expansion of the edge portion is the center portion It can be smoother than the expansion of. The edge portion of the expansion element 110, which can be inflated even more at the same pressure, is mutually opposed to the holding force of the fixing element 160 by the pressure at which it expands further, so that these two forces cancel each other out. Due to this shape of the expansion element 110, the pressure P applied to the entire surface of the wafer 1 becomes relatively uniform, thereby improving the flatness of the wafer 1 which has been polished.

The thickness of the expansion element 110 is at least 0.7 mm and less than 0.9 mm in the edge portion 111 and at least 0.9 mm and less than 1.1 mm in the central portion 112. The thickness of the expansion element 110 is not necessarily limited thereto, and any thickness distribution may be used as long as it is a thickness shape capable of transmitting a uniform pressure P to the wafer 1.

3 to 5 are cross-sectional views showing various modifications of the expansion element 110, and only a portion of the edge portion 111 to the center portion 112 of the expansion element 110 is shown.

As shown in FIG. 3, the expansion element 110 may be formed in a single stage. If the thickness is increased only once in the middle region from the edge portion 111 of the expansion element 110 to the center portion 112, the manufacturing of the expansion element 110 may be facilitated.

Referring to FIG. 4, the expansion element 110 may be formed to increase in thickness in multiple stages from the edge portion 111 to the central portion 112. 4 is formed to form four stages, but is not necessarily limited thereto, and any one of three or five stages or more may be formed as long as the pressure P may be uniformly applied to the wafer 1. Can be. This multistage shape has advantages in that the fabrication is somewhat more complicated than single stage, but the pressure P delivered to the wafer 1 can be more uniformly maintained than single stage.

FIG. 5 shows a variant in which the thickness varies continuously from the edge portion 111 to the central portion 112 of the expansion element 110. Forming the expansion element 110 such that the thickness varies continuously from the edge portion 111 to the center portion 112, although the production is somewhat complicated, it can deliver a more uniform pressure (P) than the multi-stage Can be. In addition, there is no advantage that a large load is not concentrated in a certain portion during expansion of the expansion element 110 because there is no part that the thickness is dramatically changed throughout the expansion element 110 than single-stage or multi-stage. Therefore, it is advantageous in that the service life of the expansion element 110 is increased.

The wafer compaction apparatus 100 according to the present invention may constitute a polishing apparatus together with a polishing machine. The polishing apparatus including the wafer compaction apparatus 100 of the present invention can further improve the flatness of the wafer 1 as well as the surface mirroring, as compared with the conventional polishing apparatus. In addition, in the conventional wafer crimping device 10, since only a certain portion of the pressure must be used in order to deliver a uniform pressure to the entire surface of the wafer 1, the device should be made larger than necessary, but the wafer crimping device 100 of the present invention Since the pressure P is uniformly transmitted to the entire surface of the wafer 1, the size can be relatively reduced. Accordingly, the polishing apparatus with the wafer compaction apparatus 100 of the present invention can also be manufactured relatively small.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Included in this specification.

1 schematically illustrates a cross-sectional view and pressure transfer distribution of a conventional wafer compaction apparatus;

2 schematically shows a cross-sectional view and a pressure transfer distribution of a wafer compaction apparatus according to the present invention;

3 is a variant of the expansion element according to the invention;

4 is another variant of an expansion element according to the invention;

5 is another variant of the expansion element according to the invention.

<Description of the symbols for the main parts of the drawings>

1: wafer 2: pad

10: wafer compaction apparatus 11: expansion element

12 pneumatic line 13 back plate

14 chamber 15 template assembly

16: fixed element 100: wafer pressing machine

110: expansion element 111: edge portion

112: central portion 120: pneumatic line

130: back plate 140: chamber

150: template assembly 160: fixed element

P: pressure

Claims (13)

chamber; A pressure providing unit for providing air pressure to the chamber; And A pressurizing unit pressurizing a wafer using the pneumatic pressure; Including, The pressurizing unit, An expansion element having a variable thickness and selectively expanded by the pneumatic pressure; Wafer pressing device of the polishing apparatus comprising a. The method of claim 1, A template assembly in contact with the expansion element to receive the expansion force of the expansion element to pressurize the wafer; And And a holding element for holding an edge of the expansion element. The method of claim 1, Wafer pressing device of the polishing device, characterized in that the material of the expansion element is made of rubber. The method according to any one of claims 1 to 3, And said expansion element has an edge portion thinner than a central portion. The method of claim 4, wherein The thickness of the edge portion of the expansion element is 15% to 25% thinner than the central portion. The method of claim 4, wherein The expansion element is a wafer pressing device of the polishing apparatus, characterized in that formed in a single-ended type becomes thicker toward the center. The method of claim 4, wherein The expansion element is a wafer compaction apparatus of the polishing apparatus, characterized in that formed in a multi-stage, the thickness becomes thicker toward the center. The method of claim 4, wherein And said expansion element is continuously thickened toward the center thereof. The method of claim 4, wherein And the thickness of the center portion of the expansion element is at least 0.9 mm and at most 1.1 mm, and the thickness of the edge portion of the expansion element is at least 0.7 mm and less than 0.9 mm. A grinding machine; And A wafer crimping device, disposed at a position opposite the grinder, for crimping a wafer to the grinder; Including, The wafer crimping apparatus, chamber; A pressure providing unit for providing pneumatic pressure to the chamber; A pressurizing unit for applying pressure to the wafer using the pneumatic pressure and including an expansion element; A template assembly in contact with the expansion element for transmitting expansion force from the expansion element to the wafer; And A fixing element for fixing an edge portion of the expansion element; Wherein the expansion element is a polishing device, characterized in that the thickness is variable, selectively expanded by the pneumatic, made of rubber, the thickness of the edge portion is thinner than the central portion. The method of claim 10, Polishing apparatus, characterized in that the thickness thickened once from the edge portion of the expansion element toward the center portion. The method of claim 10, Polishing apparatus, characterized in that the thickness becomes thicker from the edge portion of the expansion element toward the center portion in multiple stages. The method of claim 10, Polishing apparatus, characterized in that the thickness is continuously thickened from the edge portion of the expansion element toward the center portion.

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