CN112476227A

CN112476227A - Chemical mechanical polishing device

Info

Publication number: CN112476227A
Application number: CN202011355285.2A
Authority: CN
Inventors: 陈慧新; 李松; 宋振伟; 张守龙
Original assignee: Hua Hong Semiconductor Wuxi Co Ltd
Current assignee: Hua Hong Semiconductor Wuxi Co Ltd
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2021-03-12

Abstract

The invention relates to a chemical mechanical polishing device, which comprises a polishing pad, a polishing head and a polishing head, wherein the polishing pad is stuck on a polishing disk; a polishing head for holding a wafer to be polished and applying a downward pressure to the wafer to be polished to attach the surface of the wafer to be polished downward to the polishing pad; and the cleaning device is arranged on the grinding pad and used for scraping the surface of the grinding pad and removing byproducts on the grinding pad in the grinding operation process, wherein the cleaning device comprises a diamond grinding disc, the surface of the diamond grinding disc comprises a plurality of diamonds, the pressure applied to the grinding pad by the diamond grinding disc is gradually increased from the beginning to the end of the life cycle of the grinding pad, the grinding rate stability can be ensured, and meanwhile, the service life can be properly prolonged.

Description

Chemical mechanical polishing device

Technical Field

The invention relates to a chemical mechanical polishing device, in particular to a device with high chemical mechanical polishing rate stability.

Background

Chemical Mechanical Polishing (CMP) is a common process used in semiconductor integrated circuit manufacturing. Chemical Mechanical Polishing (CMP) is a complex process that planarizes the surface of a wafer by relative motion between the wafer and a polishing pad using equipment commonly referred to as a grinder or polisher. When the grinding head rotates under the drive of the motor, the grinding head rotates relatively. Meanwhile, the grinding fluid is conveyed to the grinding pad through a grinding fluid supply pipe (tube) and is uniformly distributed on the grinding pad through centrifugal force, chemical components in the grinding fluid and the ground wafer are subjected to chemical reaction, insoluble substances are converted into soluble substances (chemical reaction process), and then the soluble substances are removed from the surface of the polished wafer through mechanical friction, so that the surface material of the wafer is removed through the combination of mechanical action and chemical reaction, and the global planarization effect is achieved.

By-products such as grinding particles and the like generated in the wafer grinding process are remained on the surface of the grinding pad and in the groove, if the by-products are not cleaned in time, the wafer can be scratched, and products can be scrapped when the by-products are serious.

Disclosure of Invention

The present invention provides a chemical mechanical polishing apparatus, comprising: a polishing pad adhered to the polishing plate; a polishing head for holding a wafer to be polished and applying a downward pressure to the wafer to be polished to attach the surface of the wafer to be polished downward to the polishing pad; and a cleaning device arranged on the grinding pad and used for scraping off the surface of the grinding pad and removing byproducts on the grinding pad in the grinding operation process, wherein the cleaning device comprises a diamond grinding disc, the surface of the diamond grinding disc comprises a plurality of diamonds, and the pressure applied to the grinding pad by the diamond grinding disc is gradually increased from the beginning to the end of the life cycle of the grinding pad.

Further, if m wafers can be polished by the polishing pad throughout the life cycle, the m wafers are divided into n segments from the beginning to the end of the life cycle of the polishing pad, wherein the pressure applied to the polishing pad from the first segment to the nth segment of the diamond polishing disk is gradually increased.

Further, the diamond polishing disk applies the same pressure to the polishing pad for each wafer in each segment.

Furthermore, the pressure applied by the diamond polishing disc to the polishing pad is taken as the reference and is marked as 0 in the middle of the life cycle of the polishing pad; at the beginning of the life cycle of the polishing pad, the pressure applied to the polishing pad by the diamond polishing disk is reduced by 6% relative to the pressure applied at the middle stage of the life cycle of the polishing pad, the pressure applied to the polishing pad by the diamond polishing disk is gradually reduced by 5%, 4%, 3%, 2%, 1% relative to the pressure applied at the middle stage of the life cycle of the polishing pad along with the increase of the life cycle of the polishing pad, then the pressure applied to the polishing pad by the diamond polishing disk is gradually increased by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% relative to the pressure applied at the middle stage of the life cycle of the polishing pad along with the increase of the life cycle of the polishing pad, and a database of the pressure correction ratio of the diamond polishing disk, which is changed along with the increase of the life cycle of the polishing pad, is obtained.

Furthermore, the cleaning device comprises a grinding rod, a diamond grinding disc is arranged on the grinding rod, and the diamond grinding disc applies different pressures to the grinding pad through the grinding rod.

Furthermore, the diamond polishing device also comprises a control device, wherein the control device controls the polishing rod, so that the pressure applied to the polishing pad by the diamond polishing disk is gradually increased from the beginning to the end of the life cycle of the polishing pad.

Further, the diamond polishing disk and the polishing pad rotate in opposite directions.

Furthermore, the diamond grinding disc and the second cleaning disc rotate in opposite directions.

Further, the diamond polishing disk has a range of motion greater than the diameter of the wafer and not exceeding the radius of the polishing pad.

Furthermore, the polishing device also comprises a control device, the control device controls the polishing rod, a database of the pressure correction proportion of the diamond polishing disk changing along with the increase of the life time of the polishing pad is led into the control device, and the control device controls the polishing rod to enable the pressure applied to the polishing pad by the diamond polishing disk to gradually increase from the beginning to the end of the life cycle of the polishing pad.

Drawings

FIG. 1 is a schematic view of a chemical mechanical polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph illustrating the change in polishing rate with increasing lifetime of a polishing pad according to the prior art.

FIG. 3 is a schematic view of a diamond abrasive disk after use for a period of time.

FIG. 4 is a graph illustrating the polishing rate as the life time of the polishing pad increases according to one embodiment of the present invention.

FIG. 5 is a schematic diagram of the diamond polishing disc pressure correction ratio varying with increasing polishing pad lifetime according to one embodiment of the present invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and the same reference numerals denote the same elements throughout. It will be understood that when an element or layer is referred to as being "on" …, "adjacent to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial relationship terms such as "under …", "under …", "below", "under …", "above …", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

Referring to the schematic view of the chemical mechanical polishing apparatus shown in fig. 1, as shown in fig. 1, the chemical mechanical polishing apparatus includes: a polishing pad 11 attached to the polishing platen 10; a polishing head 20 holding a wafer 30 to be polished and applying a downward pressure to the wafer 30 to be polished to attach the surface to be polished of the wafer 30 downward onto the polishing pad 11; and a cleaning device 40 disposed on the polishing pad 11 for scraping off the surface of the polishing pad 11 and removing by-products from the polishing pad 11 during the polishing operation, wherein the cleaning device 40 includes a diamond polishing disk 41, the surface of the diamond polishing disk 41 includes a plurality of diamonds, and the diamonds are pressed against the polishing pad 11 by a downward pressure applied to the diamond polishing disk 41 to remove by-products from the polishing pad 11.

The polishing pad 11 and the diamond polishing disk 41 are consumables and have a certain life cycle (life). In the production process of a semiconductor device, the grinding rate of materials is reduced along with the increase of consumable life, the grinding rate is in periodicity related to PM, and due to the fact that the stability of the grinding rate is poor, the influence of life on RR can be compensated by a large-volume product through APC (automatic control program) adjustment time; and the small-amount product needs Pilot Run at different Life time, grinding time is adjusted, and the product thickness stability is ensured, but the Pilot Run Lot often has abnormal buffer thickness and needs to be reworked, so that more working pressure is caused. Specifically, referring to fig. 2, fig. 2 is a schematic diagram illustrating the polishing rate varying with the life time of the polishing pad, and as shown in fig. 2, the polishing rate decreases with the number of wafers polished by the polishing pad. After long-term research, the inventor finds that the reason is mainly that: firstly, the polishing pad is made of polymer, as the Life time increases, the Grove depth becomes shallow, the groove polishing liquid accumulation becomes less, the removal capability of the attachments of the diamond polishing disc becomes poor, the surface of the polishing pad becomes smooth, the accumulation of foaming holes is less, and the polishing rate is reduced; further, as the service life of the diamond polishing disk increases, the surface diamond is passivated, the protruding height of the diamond becomes lower, the repairing capability to the polishing pad is reduced, and the surface of the polishing pad in the last stage becomes smooth, which leads to the reduction of the polishing rate, specifically, refer to the schematic diagram of the diamond polishing disk in fig. 3 after being used for a period of time, and as shown in fig. 3, the protruding height of the diamond becomes lower.

In view of the above, an embodiment of the present invention provides a chemical mechanical polishing apparatus, which can improve the stability of the polishing rate of the chemical mechanical polishing apparatus, and is characterized in that the pressure applied by the diamond polishing disk 41 to the polishing pad 11 is gradually increased from the beginning to the end of the life cycle of the polishing pad 11, as compared with the chemical mechanical polishing apparatus shown in fig. 1.

Therefore, at the initial stage of the life cycle of the grinding pad, diamonds of the diamond grinding disc are protruded, the repairing capability is strong, but the excessive consumption of the grinding pad is easily caused, the grinding rate at the later stage is insufficient, the consumption of the grinding pad can be reduced by applying smaller pressure to the grinding disc, and the grinding rate is slightly reduced; the diamond grinding disc diamond grinding pad finishing capacity is reduced along with the increase of the life cycle of the grinding pad to the end of the life cycle of the grinding pad, the micro-environment of the surface of the grinding pad is smooth, the grinding pad is finished by increasing the pressure, the rough surface of the grinding pad is ensured, and the grinding rate is increased. Specifically, referring to fig. 4, fig. 4 is a schematic diagram illustrating the polishing rate of the polishing pad of the present invention varying with the lifetime of the polishing pad, as shown in fig. 4, the polishing rate of the polishing pad is substantially constant with the number of wafers polished by the polishing pad.

Specifically, referring to fig. 5, fig. 5 is a schematic diagram illustrating the pressure correction ratio of the diamond polishing pad according to an embodiment of the present invention changing with the increase of the lifetime of the polishing pad. From the beginning to the end of the life cycle of the polishing pad 11, the diamond polishing disk 41 applies a gradually increasing pressure to the polishing pad 11, more specifically: if m wafers can be polished throughout the life cycle of the polishing pad, the m wafers are divided into n segments from the beginning to the end of the life cycle of the polishing pad, wherein the pressure applied to the polishing pad 11 from the first segment to the nth segment of diamond polishing disk 41 is gradually increased. Further, in one embodiment, the diamond polishing disk 41 applies the same pressure to the polishing pad 11 for each wafer in each segment. As shown in fig. 5, the pressure applied by the diamond polishing disk 41 to the polishing pad 11 is marked as 0 with reference to the middle stage of the life cycle of the polishing pad 11; at the beginning of the life cycle of the polishing pad 11, the pressure applied by the diamond polishing disk 41 to the polishing pad 11 is reduced by 6% relative to the pressure applied at the middle of the life cycle of the polishing pad 11, and as the life cycle of the polishing pad 11 increases, the pressure applied by the diamond polishing disk 41 to the polishing pad 11 is reduced by 5%, 4%, 3%, 2%, 1% in stages relative to the pressure applied at the middle of the life cycle of the polishing pad 11, and then to the middle of the life cycle of the polishing pad 11, and then as the life cycle of the polishing pad 11 increases, the pressure applied by the diamond polishing disk 41 to the polishing pad 11 increases by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% in stages relative to the pressure applied at the middle of the life cycle of the polishing pad 11, so as to obtain a database in which the pressure correction ratio of the diamond polishing disk varies with the increase of the life time.

In one embodiment, the cleaning device 40 includes a polishing rod 43, a diamond polishing disk 41 is disposed on the polishing rod 43, and the diamond polishing disk 41 applies different pressures to the polishing pad through the polishing rod 43. More specifically, in one embodiment of the present invention, the chemical mechanical polishing apparatus further comprises a control device, the control device controls the polishing rod 43 such that the pressure applied by the diamond polishing disk 41 to the polishing pad 11 gradually increases from the beginning to the end of the life cycle of the polishing pad 11. Furthermore, a database showing the diamond polishing disk pressure correction ratio shown in FIG. 5, which varies with the increase of the life time of the polishing pad, is introduced into the control device, and the polishing rod 43 is controlled by the control device so that the pressure applied to the polishing pad 11 by the diamond polishing disk 41 gradually increases from the start to the end of the life cycle of the polishing pad 11,

in one embodiment, the diamond polishing disk 41 rotates in the opposite direction to the polishing pad 11. In one embodiment, the diamond abrasive disk 41 and the second conditioning disk 42 rotate in opposite directions.

In one embodiment, the range of motion of the diamond polishing disk 41 is greater than the diameter of the wafer and does not exceed the radius of the polishing pad 11, ensuring that the wafer is within the range of the diamond polishing disk 41 cleaning the polishing pad 11.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chemical mechanical polishing apparatus, comprising:

a polishing pad adhered to the polishing plate;

a polishing head for holding a wafer to be polished and applying a downward pressure to the wafer to be polished to attach the surface of the wafer to be polished downward to the polishing pad; and

and the cleaning device is arranged on the grinding pad and is used for scraping the surface of the grinding pad and removing byproducts from the grinding pad in the grinding operation process, wherein the cleaning device comprises a diamond grinding disc, the surface of the diamond grinding disc comprises a plurality of diamonds, and the pressure applied to the grinding pad by the diamond grinding disc is gradually increased from the beginning to the end of the life cycle of the grinding pad.

2. The chemical mechanical polishing apparatus of claim 1, wherein if the polishing pad can polish m wafers throughout the life cycle, the m wafers are divided into n segments from beginning to end of the life cycle of the polishing pad, wherein the pressure applied to the polishing pad from the first segment to the nth segment of the diamond polishing disk is gradually increased.

3. The chemical mechanical polishing apparatus of claim 2, wherein the diamond polishing disk applies the same pressure to the polishing pad for each wafer in each segment.

4. The chemical mechanical polishing apparatus of claim 3, wherein the pressure applied by the diamond polishing disk to the polishing pad is referenced to 0 at the middle of the life cycle of the polishing pad; at the beginning of the life cycle of the polishing pad, the pressure applied to the polishing pad by the diamond polishing disk is reduced by 6% relative to the pressure applied at the middle stage of the life cycle of the polishing pad, the pressure applied to the polishing pad by the diamond polishing disk is gradually reduced by 5%, 4%, 3%, 2%, 1% relative to the pressure applied at the middle stage of the life cycle of the polishing pad along with the increase of the life cycle of the polishing pad, then the pressure applied to the polishing pad by the diamond polishing disk is gradually increased by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% relative to the pressure applied at the middle stage of the life cycle of the polishing pad along with the increase of the life cycle of the polishing pad, and a database of the pressure correction ratio of the diamond polishing disk, which is changed along with the increase of the life cycle of the polishing pad, is obtained.

5. The chemical mechanical polishing apparatus of claim 1, wherein the cleaning device comprises a polishing rod, and the diamond polishing disk is disposed on the polishing rod, and the diamond polishing disk applies different pressures to the polishing pad through the polishing rod.

6. The chemical mechanical polishing apparatus of claim 5, further comprising a control device, wherein the control device controls the polishing rod such that the pressure applied by the diamond polishing disk to the polishing pad is gradually increased from the beginning to the end of the life cycle of the polishing pad.

7. The chemical mechanical polishing apparatus of claim 1, wherein the diamond polishing disk and the polishing pad rotate in opposite directions.

8. The chemical mechanical polishing apparatus of claim 1, wherein the diamond polishing disk and the second cleaning disk rotate in opposite directions.

9. The chemical mechanical polishing apparatus of claim 1, wherein the diamond polishing disk has a range of motion greater than the diameter of the wafer and not exceeding the radius of the polishing pad.

10. The chemical mechanical polishing apparatus of claim 4, further comprising a control device for controlling the polishing rod to introduce a database of diamond polishing disk pressure correction ratios that vary with increasing polishing pad life time into the control device, and the control device controls the polishing rod such that the diamond polishing disk applies increasing pressure to the polishing pad from the beginning to the end of the polishing pad life cycle.