JP3660448B2 - Semiconductor device manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for planarizing an interlayer insulating film and a metal film of a multilayer wiring.
[0002]
[Prior art]
Interlayer insulation film (SiO2), which is a major issue in multilayer wiring technology₂As a processing method that realizes improvement in flatness, CMP (Chemical Mechanical Polishing) is known in which the surface of the interlayer insulating film is polished using a polishing liquid that is rich in solid phase reactivity with the interlayer insulating film.
[0003]
In the CMP process, there is a problem that the actual polishing amount becomes smaller than the set polishing amount due to deterioration of the work surface of the polishing pad as the polishing process proceeds. Thus, in order to solve such problems, many attempts have been made to improve the dressing technology of the polishing pad. As one of them, a “planarization method and planarization apparatus for semiconductor device” described in Japanese Patent Laid-Open No. 7-297195 shown below is known.
[0004]
In Japanese Patent Application Laid-Open No. 7-297195, in the conventional CMP process, a region in which abrasive grains cannot be locally retained on the work surface of the polishing pad is generated due to deterioration of the work surface of the polishing pad as the polishing process proceeds. Therefore, there has been a problem that a stable polishing efficiency cannot be maintained. Furthermore, it is stated that it is necessary not only to ensure the flatness of the surface of the interlayer insulating film but also to ensure the uniformity of the film thickness of the interlayer insulating film.
[0005]
Therefore, in JP-A-7-297195, the polishing pad is continuously dressed with a diamond dresser or the like during the polishing process, and the fuzzy state on the work surface of the polishing pad is maintained uniformly. We are trying to solve the problem. Furthermore, the work surface of the polishing pad is shaped into a curved surface shape with a curvature equal to the curvature of the wafer, and the curved surface shape is transferred to the surface of the interlayer insulating film, thereby ensuring the uniformity of the film thickness of the interlayer insulating film. .
[0006]
[Problems to be solved by the invention]
In CMP processing, the life of the polishing pad and the surface roughness of the polished surface may be greatly affected by the difference in the distribution of cutting edges (particularly the distribution of cutting edges in the depth direction) on the work surface of the polishing pad. Are known. However, Japanese Patent Application Laid-Open No. 7-297195 focuses only on maintaining the work surface of the polishing pad in a uniform state by dressing, and a stable and dense cutting edge array on the work surface of the polishing pad by dressing. The need to form is not taken into account at all. Therefore, it is not always possible to create a good polished surface. Moreover, there is a possibility that the deterioration of the polishing pad progresses unexpectedly.
[0007]
Accordingly, a first object of the present invention is to form a fine cutting edge array that is hard to deteriorate and has a good sharpness on the work surface of the polishing tool. A second object is to stabilize the polishing efficiency by maintaining such a cutting edge arrangement during the polishing process.
[0008]
By the way, in the dress-driven polishing process, if the optimum point of the dress condition can be grasped, it is generally possible to perform a more economical polishing process while exhibiting excellent polishing performance for the polishing tool. Are known. Therefore, in dress-driven polishing, grasping the optimum point of dress conditions is an important issue.
[0009]
Accordingly, a third object of the present invention is to make it possible to grasp the optimum point of the dress condition during the polishing process.
[0010]
[Means for Solving the Problems]
  The present invention
  A polishing method for polishing a workpiece by sliding a polishing pad and a workpiece,
Comparing the shape data of the polishing pad with the target shape data, and when the difference between the two data is equal to or less than a predetermined threshold due to polishing of the workpiece, the polishing pad is moved using the first dressing tool. After the dressing, there is provided a polishing method characterized in that the polishing pad is dressed by using a second dressing tool whose cutting edge arrangement is smaller than the first dressing tool.
The present invention also provides:
A polishing apparatus for polishing a surface of the workpiece with a work surface of the polishing pad by applying a relative motion between the workpiece and the polishing pad,
A first dressing tool;
A second dressing tool having a smaller cutting edge arrangement than the first dressing tool;
First pressing means for pressing the first dressing tool against the work surface of the polishing pad;
A second pressurizing means for pressing the second dressing tool against the work surface of the polishing pad;
Moving means for providing a relative motion between the first or second dressing tool pressed against the work surface of the polishing pad and the polishing pad;
Detecting means for detecting shape data of a work surface of the polishing pad;
The shape data detected by the detection means and the target shape data are compared, and when the difference between the two data is equal to or less than a predetermined threshold value, the first pressure means is used for the first dress. Control means for pressing the second dressing tool against the polishing pad after the tool is pressed against the polishing pad;
A polishing apparatus is provided.
[0011]
According to the manufacturing method of the semiconductor device, the work surface of the polishing tool can be dressed with the dressing tools having different roughness of the cutting edge arrangement. Therefore, for example, as shown in FIG. 3 (b), first, the dressing tool having a large cutting edge array is used to roughly dress the work surface of the polishing tool, and then, as shown in FIG. 3 (c). In addition, if the cutting edge distribution in the depth direction is corrected using a dressing tool having a small cutting edge arrangement, a substantial polishing action is exerted on the surface of the workpiece A on the work surface of the polishing tool 14. It is possible to regenerate the cutting edge 39 having the fine cutting edge 39a to be provided and having the groove 9b that holds the polishing liquid 16 stably. Further, since the cutting edge 39a that gives a substantial polishing action to the surface of the workpiece A is very dense and the effective contact width between the workpiece A and the cutting edge 39 is large, the cutting edge is not easily worn.
[0012]
In addition, if the dressing with these two types of dressing tools is periodically or continuously applied to the work surface of the polishing tool during the polishing process, the above-described dense and stable cutting edge array can be obtained. Can be maintained.
[0013]
Furthermore, if the surface shape of the work surface of the polishing tool is measured in-process with a sensor during polishing, the state of the work surface of the polishing performance of the polishing tool can be grasped in real time based on the output of the sensor. Therefore, the optimum point of the dress condition can be detected during the polishing process. If the dressing is performed on the work surface of the polishing tool with the above-mentioned two kinds of dressing tools under this dressing condition, the polishing efficiency of the polishing tool can be maintained while maintaining the excellent polishing performance of the polishing tool. Can be improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment according to the present invention will be described with reference to the accompanying drawings.
[0015]
In accordance with the control of the CNC apparatus, the polishing apparatus supplies the polishing liquid onto the work surface of the polishing pad, presses the work against the work surface of the polishing pad, and slides between the work surface of the polishing pad and the surface of the work. CMP that finally performs mirror finish on the surface of the work piece by performing dynamic motion and removing fine irregularities on the surface of the work piece by the synergistic effect of mechanical polishing action and chemical polishing action by the polishing liquid Has a polishing function. Furthermore, it has a dressing function for performing dressing on the work surface of the polishing pad periodically or continuously during the polishing process.
[0016]
Hereinafter, the basic configuration of the polishing apparatus will be described separately for each function with reference to FIG.
[0017]
First, a basic configuration for realizing the CMP polishing function will be described.
[0018]
The polishing apparatus includes a polishing surface plate 13 to which a polishing pad 14 is attached, a grindstone shaft rotating mechanism that rotates a tool shaft 100 to which the polishing surface plate 13 is attached, a chuck 4 that holds a workpiece A, and a chuck 4. A spindle rotating mechanism that rotates the attached spindle 21, a feed mechanism that moves the polishing head containing the spindle 21 in the x direction, a cutting mechanism that moves the spindle 21 in and out of the spindle head, and a work surface 14 a of the polishing pad 14. A pressurizing mechanism (see FIG. 2) for pressing the workpiece A, a polishing liquid supply mechanism for supplying the polishing liquid 16a onto the work surface 14a of the polishing pad 14, and a CNC device 35 for controlling each mechanism are provided. However, it is necessary to use a slurry rich in solid phase reactivity with the workpiece A as the polishing liquid 16. For example, when polishing an interlayer insulating film formed on a Si wafer, SiO having a particle size of about 30 nm is used in an alkaline solution.₂It is desirable to use a slurry mixed with about 20% abrasive grains or a slurry mixed with about 20% cerium oxide abrasive grains. When polishing a metal film formed on a Si wafer, it is desirable to use a slurry in which about 20% of cerium oxide abrasive grains or alumina abrasive grains are mixed in an acidic solution. And it is necessary to use for the polishing pad 14 the polishing pad formed with the synthetic resin excellent in abrasion resistance and organic-solvent resistance. For example, when polishing an interlayer insulating film formed on a Si wafer, it is desirable to use a polishing pad formed of a hard foam polyurethane synthetic resin.
[0019]
The polishing liquid supply mechanism drives the pump (not shown) with a dedicated motor (not shown), thereby allowing the polishing liquid 16 filled in a tank (not shown) provided in the base 25 of the polishing apparatus to It is discharged from the polishing liquid supply pipe 15 toward the work surface 14 a of the polishing pad 14. A valve (not shown) for adjusting the flow rate of the polishing liquid 16 is attached to the polishing liquid supply pipe 15 so that an appropriate amount of the polishing liquid 16 is supplied onto the work surface 14a of the polishing pad 14. The opening degree of the valve is controlled by the CNC device 35.
[0020]
In addition, the tool rotation mechanism rotates the tool shaft 100 by transmitting the output of the servo motor 28 to the tool shaft 100 via a speed reducer (not shown). The servo motor 28 is speed-controlled by a speed controller (not shown) so that fluctuations in the rotation speed of the tool shaft 100 are suppressed.
[0021]
The main shaft rotating mechanism rotates the main shaft 21 by transmitting the output of the servo motor 22 to the main shaft 21 via a speed reducer (not shown). The servo motor 22 is speed-controlled by a speed controller so that fluctuations in the rotation speed of the main shaft 21 are suppressed.
[0022]
The feed mechanism transmits the output of a servo motor (not shown) to a spline formed on the polishing head feed ball screw 30 via a speed reducer (not shown), thereby moving the polishing head 29 in the x direction. Move. The rotation angle of the servo motor is numerically controlled by the CNC device 35.
[0023]
In addition, the cutting mechanism moves the spindle 21 in and out of the polishing head 29 by transmitting the output of the air cylinder 24 to the spindle entrance / exit adjustment quill 23. Stoppers provided at a plurality of locations (usually three or five) on the inner periphery of the polishing head 29 in order to maintain the axial center position of the main shaft 21 and to maintain the cutting amount given to the workpiece A by the cutting mechanism. 26 is configured to completely restrain the movement of the spindle entry / exit adjustment quill 23 by the output of each air cylinder 27.
[0024]
Note that the chuck 4 that holds the workpiece A and the pressurizing mechanism that presses the workpiece A against the work surface 14a of the polishing pad 14 respectively function as a holding tool for the dressing tool and the dressing tool as the polishing pad. 14 also functions as a pressurizing mechanism that presses against the 14 work surface 14a, and the structure thereof will be described later.
[0025]
Next, a basic configuration for realizing the dressing function will be described with reference to FIGS. 1 and 2.
[0026]
As shown in FIG. 2, the polishing apparatus includes a stylus type surface roughness meter 57 that measures the surface shape of the work surface 14 a of the polishing pad 14 in-process, and a stylus type surface roughness on the work surface 14 a of the polishing pad 14. A slider (not shown) for reciprocally moving the total 57 in the x direction, two or more types of dressing grindstones (in this embodiment, two types of dressing grindstones 11a and 11b), and a polishing pad 14 A pressurizing mechanism (not shown) for pressing the dressing grindstones 11a and 11b against the work surface 14a is provided.
[0027]
The stylus surface roughness meter 57 moves while relatively rotating on the work surface 14a of the polishing pad 14 by the rotation of the polishing pad 14 and the reciprocation in the x direction that the slider gives to the stylus surface roughness meter 57. To do. Accordingly, since the stylus 57b of the stylus surface roughness meter 57 scans the work surface 14a of the polishing pad 14, the surface roughness of the work surface 14a of the polishing pad 14 is measured over the entire surface. The output signal K from the stylus type surface roughness meter 57₁Is an AD converter and digital shape data K₁After being converted to, it is input to the CNC device 35. A sliding surface with a small friction coefficient is formed on the lower surface 57a of the stylus surface roughness meter 57 so that the stylus surface roughness meter 57 smoothly moves relative to the work surface 14a of the polishing pad 14. .
[0028]
Further, as shown in FIG. 1, cavities 5b and 5c are formed on the end face of the chuck 4 along the outer periphery, and air bags 6b and 6c are packed in the inside thereof. One or more small dressing grindstones 11a are attached to the surface of one airbag 6b, and one or more large dressing grindstones 11b are attached to the surface of the other airbag 6c. Yes. On the contrary, a dress grindstone 11b having a large particle size is attached to the surface of one airbag 6b, and a dress grindstone 11a having a small particle size is attached to the surface of the other airbag 6c. It doesn't matter if you do. Further, a cavity 5a is formed in the end surface of the chuck 4 also in the central region, and the airbag 6a is also packed therein. And the rigid member 3 which stuck the support body 2 which adsorb | sucks the workpiece A is attached to the surface of this airbag 6a. The air supply holes of the airbags 6a, 6b, and 6c are respectively formed in the flow paths 17a, 17b, and 17c that connect between the cavity portions 5a, 5b, and 5c into which the air bags 6a, 6b, and 6c are packed and the gas splitting slip ring 20. It is connected to the channel end.
[0029]
Further, when the flow path connecting the external compressor and the flow paths 17a, 17b, and 17c is opened by the opening degree control of the gas diversion slip ring valve of the CNC device 35, the pressurizing mechanism is externally connected. Gas supplied from a compressor (for example, N₂, Air, etc.) are filled in the airbags 6a, 6b, 6c, respectively. When the airbag 6a is inflated by the CNC device 35, the polishing pressure acting between the workpiece A and the polishing pad 14 increases, and when the airbag 6b is inflated, the dressing grindstone 11a and the polishing pad are increased. If the polishing pressure working between 14 and the airbag 6c is inflated, the polishing pressure working between the dressing grindstone 11b and the polishing pad 14 increases. Further, when the exhaust passage connecting the outside and each of the passages 17a, 17b, and 17c is opened by the opening degree control of the gas diversion slip ring valve of the CNC device 35, the pressurizing mechanism The gas filled in the bags 6a, 6b, 6c is discharged to the outside. Thereby, if the airbag 6a is deflated, the polishing pressure working between the workpiece A and the polishing pad 14 is reduced, and if the airbag 6b is deflated, it is between the dressing grindstone 11a and the polishing pad 14. When the working polishing pressure is reduced and the airbag 6c is deflated, the polishing pressure working between the dressing grindstone 11b and the polishing pad 14 is reduced.
[0030]
Hereinafter, the processing executed by the CNC device 35 during polishing will be described with reference to FIG.
[0031]
The CNC device 35 controls the polishing liquid supply mechanism so that the processed polishing liquid 16 starts to be supplied to the work surface 14a of the polishing pad 14, and a predetermined cut is given to the workpiece A. So as to control the cutting mechanism. Furthermore, after controlling the pressurizing mechanism so that a polishing pressure is generated between the polishing pad 14 and the workpiece A, sliding between the surface of the workpiece A and the work surface 14a of the polishing pad 14 is started. Thus, the tool rotation mechanism, the spindle rotation mechanism, and the feed mechanism are controlled. In the present embodiment, considering the difference between the peripheral speed near the outer periphery on the work surface 14 a of the polishing pad 14 and the peripheral speed near the rotation center, the workpiece A approaches the rotation center of the polishing pad 14. The feed speed v of the polishing head 29 is decelerated.
[0032]
In the meantime, the CNC device 35 further receives digital shape data K inputted in real time from the stylus type surface roughness meter 57 side.₁And the difference ΔK from the predetermined target work surface shape data K is sequentially calculated. Note that the target work surface shape data K here is shape data representing an ideal surface shape of the work surface of the polishing pad. Then, the transition of the polishing performance of the polishing pad during polishing is determined by comparing the calculated difference ΔK with the threshold value. That is, when the difference ΔK is equal to or greater than the first threshold, it is determined that the polishing performance of the polishing pad has deteriorated, and the following dressing process is executed.
[0033]
First, the CNC device 35 calculates the flow rate of the gas to be supplied to the airbag 6b of the pressurizing mechanism, and based on the result, controls the opening degree of the gas ring slip ring valve of the pressurizing mechanism. The flow path connecting the external compressor and the flow path 17b is opened. As a result, the airbag 6b is expanded by the gas supplied from the external compressor, and a polishing pressure is generated between the dressing grindstone 11a having a large particle size and the work surface 14a of the polishing pad 14. As a result, the work surface 14a of the polishing pad 14 is dressed by the dressing grindstone 11a having a large particle size. Then, the CNC device 35 performs threshold processing on the difference ΔK at an appropriate addition ratio (about 9%), and calculates the flow rate of the gas to be supplied to the airbag 6c when it becomes the second threshold value or less. Based on the result, the opening degree of the gas diversion slip ring valve of the pressurizing mechanism is controlled to open the exhaust flow path connecting the outside and the flow path 17b, and the compressor and the flow path 17c. The flow path connecting the two is opened. As a result, the gas inside the airbag 6b is discharged to the outside, the airbag 6b is deflated, and the dressing by the dressing grindstone 11b having a large particle size is completed. On the other hand, the air bag 6 c is inflated by the gas supplied from the compressor, and a polishing pressure is generated between the dressing grindstone 11 b having a small particle size and the work surface 14 a of the polishing pad 14. As a result, the work surface 14a of the polishing pad 14 is further dressed with the dressing grindstone 11a having a small particle size. Then, the CNC device 35 connects the outside and the flow path 17c by controlling the opening degree of the gas diversion slip ring valve of the pressurizing mechanism when the difference ΔK becomes equal to or smaller than the third threshold value. Open the exhaust passage. As a result, the gas inside the airbag 6c is discharged to the outside, the airbag 6c is deflated, and the dressing by the dressing grindstone 11b having a small particle size is also completed.
[0034]
By executing such a series of processes, dressing can be appropriately applied to the work surface 14a of the polishing pad 14 in accordance with the degree of deterioration of the polishing performance of the polishing pad 14 as the polishing process proceeds. That is, it is possible to perform dressing on the work surface 14a of the polishing pad 14 at the optimum dress point. Therefore, it is possible to improve the economical efficiency of the polishing process while maintaining the excellent polishing performance of the polishing pad 14.
[0035]
In the present embodiment, the CNC device 35 controls the valve attached to the gas diversion slip ring 20 based on the output data from the stylus surface roughness meter. do not have to. For example, the optimum dressing interval between the two types of dressing stones 11a and 11b may be determined in advance from experimental data or the like. In this case, it is more effective to gradually extend the dressing time per time as the polishing process proceeds. Further, instead of the stylus type surface roughness meter, other types of surface roughness meters such as a non-contact type laser surface roughness meter may be used.
[0036]
Here, the transition of the surface state of the work surface 14a of the polishing pad 14 is briefly summarized in order to help understanding of the cutting edge regeneration effect by such dressing processing.
[0037]
During the polishing process, when the cutting edge 37 of the work surface 14a of the polishing pad 14 is significantly worn as shown in FIG. 3A, the CNC device 35 determines that the polishing performance of the polishing pad 14 has deteriorated. The opening degree of the gas diversion slip ring valve of the pressurizing mechanism is controlled. Therefore, the work surface 14a of the polishing pad 14 is subjected to dressing with a dressing stone 11a having a large particle size. As a result, as shown in FIG. 3B, cutting edges 38 having a relatively rough cutting edge arrangement are formed on the work surface 14 a of the polishing pad 14. At this time, the CNC device 35 controls the opening degree of the gas diversion slip ring valve of the pressurizing mechanism. Therefore, the work surface 14a of the polishing pad 14 is further dressed with a grindstone 11b having a small particle size. As a result, as shown in FIG. 3C, the cutting edge distribution in the depth direction s is corrected, and finally, the work surface 14a of the polishing pad 14 is substantially polished onto the surface of the workpiece A. The cutting edge 39 having the dense cutting edge 39a that acts and the groove portion 9b that holds the polishing liquid 16 stably is regenerated.
[0038]
Incidentally, the polishing pad 14 having such a cutting edge arrangement is far superior to the polishing performance of a polishing pad dressed by using one type of dressing grindstone generally performed in conventional CMP processing. It is clear if these two polishing pads are actually used and compared.
[0039]
Therefore, in order to prove this, a comparative experiment was performed under the following conditions, with a 6-inch Si wafer having an interlayer insulating film formed on the surface as a polishing target. In order to calculate the polishing amount, the thickness T of the interlayer insulating film is measured at a plurality of measurement points (31 in the radial direction of the wafer and 18 in other locations) using an optical interference film thickness meter at the start of polishing.₀,. . . . , T₄₁Is measured in advance.
[0040]
Polishing conditions:
Rotational angular velocity of tool axis about 20rpm
Spindle angular velocity about 20rpm
Workpiece feed rate 2-5mm / sec
Polishing time 10 minutes
Polishing load 60kg
Polishing pad dress conditions:
Dressing tools (A) Two types of dressing stones (particle size 125μm, particle size 60μm)
(B) Only one type of dressing stone (particle size 125μm)
Dress timing At the start of polishing
After the polishing process is completed, the film thickness T of the interlayer insulating film is again obtained.₀',. . . . , T₄₁′ Was measured, and the polishing amount V was calculated using Equation (1), and then the variation ΔV of the polishing amount V was calculated using Equation (2).
[0041]
V_k= T_k-T_k′… (1)
ΔV = ± 100 (V_max-V_min) / (2V_ave(2)
Here, k is a natural number of 49 or less, and V_maxIs the maximum polishing amount, V_minIs the minimum polishing amount, V_aveIs the average polishing amount (ΣV / 49).
[0042]
As a result, as shown in FIG. 4, when only one type of dressing stone (B) is used, the variation ΔV of the polishing amount V is ± 19%. When the grinding wheel (A) was used in combination, the variation V in the polishing amount V was suppressed to ± 2.8% or less. Comparing both results, it is clear that stabilization of the polishing amount of the workpiece was achieved by using two types of dressing stones (A) in combination. In this way, when only one type of dressing stone (B) is used and when two types of dressing stones (A) are used in combination, a significant difference is caused by one type of dressing stone ( If only dressing is performed in B), the variation of the cutting edge distribution in the depth direction s on the work surface 14a of the polishing pad 14 is too large, so that the number of cutting edges that substantially exert a polishing action on the workpiece A is very large. This is because there are few (see FIG. 5).
[0043]
Further, as shown in FIG. 6, when only one type of dressing grindstone (B) is used, the polishing efficiency of the polishing pad at the initial stage of polishing was 0.1 μm / min. When the type of dressing stone (A) was used in combination, the polishing efficiency of the polishing pad at the initial stage of the polishing process was improved to about 0.14 μm / min. Comparing both results, it is clear that the polishing efficiency of the polishing pad was improved by using two types of dressing stones (A) in combination. Further, when only one type of dressing grindstone (B) was used, the polishing efficiency of the polishing pad was reduced by about 20% from the initial stage of the polishing process to the final stage of the polishing process. When the type of dressing grindstone (A) was used in combination, the polishing efficiency of the polishing pad from the beginning of polishing to the end of polishing was suppressed to about 7%. Comparing the two results, it is clear that the use of the two types of dressing stones (A) has achieved the stabilization of the polishing efficiency and the extension of the life of the polishing pad. As described above, when only one type of dressing grindstone (B) is used and when two types of dressing grindstones (A) are used in combination, there is a significant difference between one type of dressing grindstone ( This is because the cutting edge arrangement on the work surface 14a of the polishing pad 14 is too rough if only dressing is performed in B), so that the effective contact width between the workpiece A and the cutting edge is very small.
[0044]
Further, as shown in FIG. 7, the polishing apparatus was actually introduced into the multilayer wiring process, and performance evaluation of the polishing apparatus was performed.
[0045]
First, in the first wiring formation process 50, a first Al wiring layer having a width of 0.25 μm is formed on the surface of a 6-inch wafer by sputtering or the like, and then in the film formation process 51 by ECR plasma CVD or the like. An interlayer insulating film having a thickness of 1.5 μm is deposited. Thereafter, in the first planarization process 52, the surface of the interlayer insulating film is mirror-finished using this polishing apparatus. At this time, the target film thickness of the interlayer insulating film is 0.5 μm.
[0046]
At this time, as a result of measuring the film thickness of the interlayer insulating film with the optical interference type film thickness meter, it was confirmed that the film thickness variation V was suppressed to ± 2.8% or less. Moreover, as a result of measuring the surface roughness of the interlayer insulating film with a contact-type surface roughness meter and an atomic force microscope, the surface roughness R of the interlayer insulating film was_MaxWas suppressed to 0.3 nm or less. Furthermore, as a result of measuring the height of the irregularities on the surface of the interlayer insulating film in the stepped portion with a stylus type step gauge and an atomic force microscope, the height of the irregularities, which was initially 1 μm, was reduced to 0.1 μm or less. It was confirmed that the surface was flattened. The above measured values are values that can satisfy the conditions normally required for the interlayer insulating film of the ultrafine wiring with a width of 0.25 μm without difficulty.
[0047]
Then, in the contact hole forming process 53, the interlayer insulating film finished in such a good state is etched to form a contact hole for forming an electrical connection with the first Al wiring layer. Further, in the contact stud formation process 54, a contact stud is formed by embedding a conductor (for example, tungsten) in the contact hole by a selective CVD method or the like.
[0048]
Thereafter, in the second planarization process 55, the surface of the contact stud formed by the selective CVD method, which is generally considered to be uneven, is mirror-finished using this polishing apparatus.
[0049]
At this time, as a result of measuring the surface roughness of the contact stud with a contact surface roughness meter and an atomic force microscope, the surface roughness R of the contact stud_MaxIt was confirmed that was suppressed to 0.3 nm or less. This is a value indicating that the surface of the contact stud is finished in a good state suitable for an ultrafine wiring having a width of 0.25 μm. Further, when the surface of the interlayer insulating film was observed with an atomic force microscope, no unnecessary conductor film was found on the interlayer insulating film. Therefore, a minute defect on the interlayer insulating film was formed in the contact hole forming process 53. It is presumed that an unnecessary conductor film grown with nuclei as a nucleus was removed in the second planarization process.
[0050]
Thereafter, in the second wiring formation process 56, a second Al wiring having a width of 0.25 μm is formed by sputtering or the like.
[0051]
As a result of measuring the contact via resistance and wiring resistance at this point, it was found that no contact resistance defect and wiring defect that were conventionally found at this point were found. It can be easily estimated that there was no defective formation of the contact hole due to the introduction to.
[0052]
Based on the above results, it is clear that the introduction of this polishing apparatus into the multilayer wiring process makes it possible to manufacture a more reliable semiconductor device. The application of the polishing apparatus to the multilayer wiring process is only an example shown for evaluating apparatus performance. Therefore, it goes without saying that even if the present polishing apparatus is introduced into the polishing process of other parts (for example, optical elements) requiring high shape accuracy, the same beneficial effect can be achieved.
[0053]
As described above, the case where the workpiece A and the dressing grindstones 11a and 11b are integrally moved relative to the polishing pad 14 has been described as an example, but this is not necessarily required. For example, as shown in FIG. 8, a dressing grindstone dedicated driving device 50 having the same configuration as the driving device composed of the spindle feeding mechanism and other mechanisms is separately prepared, and the dressing grindstones 11a and 11b and the workpiece are processed. A may be driven independently. Even in this case, the CNC device 35 is connected to the output signal K of the stylus type surface roughness meter 35.₁It goes without saying that it is necessary to control the servo motor that drives each mechanism of the dressing grindstone dedicated driving device 50 according to the above.
[0054]
In the present embodiment, the polishing pressure applied to two types of dressing grindstones having different particle sizes is individually controlled, but this is not necessarily required. For example, as shown in FIG. 9, if the segment-shaped dressing stones 11 a and 11 b are fixed to the end face of the chuck 4 via the elastic bodies 41, both the dressing stones 11 a and 11 a are deformed by the deformation of the elastic bodies 41. An appropriate polishing pressure is applied between 11b and the polishing pad 14 in accordance with the curvature of the work surface 14a of the polishing pad 14. However, in this case, during the polishing process, the work surface 14a of the polishing pad 14 is always dressed by both the dressing grindstones 11a and 11b. Further, when the elastic body 41 is used in this way, it is not necessary to facilitate the supply of gas to the airbags 6 b and 6 c, so the layout of the both-dressing grindstones 11 a and 11 b on the end face of the chuck 4 is flexible. Can be determined. Therefore, for example, as shown in FIG. 10, a circumference 14 b virtually drawn on the work surface 14 a of the polishing pad 14.₁On top, segmented dressing stones 11a and 11b may be alternately arranged.
[0055]
Further, in the present embodiment, an apparatus configuration for polishing only one workpiece A is used, but such an apparatus configuration is not necessarily required. For example, a plurality of driving devices composed of the main spindle rotating mechanism and other mechanisms may be provided to polish a plurality of workpieces A simultaneously. However, in such a case, it is necessary to appropriately determine the arrangement of the driving devices and the like so that a plurality of workpieces do not collide on the work of the polishing pad 14 during the CMP process.
[0056]
Further, in this embodiment, a dressing grindstone is used as a dressing tool, but the same cutting edge arrangement as the work surface of the dressing grindstone is formed on the surface of a material (ceramic material, etc.) having an appropriate hardness. It is also possible to substitute the dressing grindstone with a cutting edge array having a degree of roughness.
[0057]
In the present embodiment, the airbag is used as a power source for pressing the dressing grindstone against the work surface of the polishing pad. However, the airbag is not necessarily used. For example, a piezoelectric element or the like that can convert electrical energy into mechanical energy may be used instead of the airbag. In this case, a current diverting slip ring may be used instead of the gas diverting slip ring.
[0058]
【The invention's effect】
According to the polishing apparatus and the polishing method of the present invention, it is possible to form a cutting edge array that has good sharpness and does not easily deteriorate on the work surface of the polishing tool. In addition, such a cutting edge arrangement can be maintained during the polishing process.
[0059]
Further, the optimum point of the dress condition can be grasped during the polishing process. Accordingly, it is possible to obtain an economic effect of reducing dress cost spent for polishing while exhibiting excellent polishing performance for the polishing tool.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a basic configuration of a polishing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a basic configuration of a polishing apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram showing a transition of a work surface state of a polishing pad.
FIG. 4A is a diagram showing the result of measuring the amount of polishing with a polishing pad dressed with only one type of dressing stone, and FIG. 4B is the result of dressing with only two types of dressing stones. It is the figure which showed the result of having measured the polishing amount by a polishing pad.
FIG. 5 is a view showing a working surface state of a polishing pad dressed with only one type of dressing stone.
FIG. 6 is a diagram for comparing a transition efficiency A of a polishing pad dressed with only two types of dressing stones and a transition efficiency B of a polishing pad dressed with only one type of dressing stone. is there.
FIG. 7 is a diagram for explaining a multilayer wiring process;
FIG. 8 is a diagram showing a basic configuration of a polishing apparatus according to an embodiment of the present invention.
FIG. 9 is a cross-sectional view of the chuck according to the embodiment of the present invention, and the lower view is a bottom view of the chuck according to the embodiment of the present invention.
FIG. 10 is a view showing an example of a layout of a dressing tool on an end face of a chuck.
[Explanation of symbols]
2 ... Support
3 ... Rigid member
4 ... Chuck
5a, 5b, 5c ... cavity
6a, 6b, 6c ... Airbag
11a, 11b ... Whetstone for dress
13 ... Polishing surface plate
14 ... Polishing pad
15 ... polishing liquid supply pipe
16 ... polishing liquid
17a, 17b, 17c ... flow path
20 ... Slip ring for gas diversion
21 ... Spindle
22 ... Servo motor
23 ... Spindle access adjustment quill
24 ... Air cylinder
25 ... Base
26 ... Stopper
27 ... Air cylinder
28 ... Servo motor
29 ... Polishing head
30 ... Ball screw for feeding polishing head
35 ... CNC equipment
57 ... Stylus type surface roughness tester
100 ... Tool axis

Claims (4)

A method for manufacturing a semiconductor device, comprising a planarization step of planarizing a wafer surface by CMP,
In the planarization process, compares the shape data of the polishing pad for polishing the surface of the pre-Symbol wafer and the target shape data, when the difference of the both data, and the following pre-determined threshold, the first dress after dressing the polishing pad using use tool, characterized in that as the roughness of the first blade arrangement cutting than dress tool is a dressing the polishing pad using a small second dress tool A method for manufacturing a semiconductor device. A polishing method for polishing the workpiece by sliding a polishing pad and the workpiece,
Comparing the shape data of the polishing pad with the target shape data, and when the difference between the two data is equal to or less than a predetermined threshold due to polishing of the workpiece, the polishing pad is moved using the first dressing tool. A polishing method, characterized in that after dressing, the polishing pad is dressed with a second dressing tool having a cutting edge arrangement smaller in roughness than the first dressing tool . A polishing apparatus for polishing a surface of the workpiece with a work surface of the polishing pad by applying a relative motion between the workpiece and the polishing pad,
A first dressing tool;
A second dressing tool having a smaller cutting edge arrangement than the first dressing tool ;
First pressing means for pressing the first dressing tool against the work surface of the polishing pad;
A second pressurizing means for pressing the second dressing tool against the work surface of the polishing pad;
Wherein the polishing pad of the first or second address for tool pressed against the working surface of a moving means for providing relative movement between said polishing pad,
Detecting means for detecting shape data of a work surface of the polishing pad;
The shape data detected by the detection means and the target shape data are compared, and when the difference between the two data is equal to or less than a predetermined threshold , the first pressurizing means is used for the first dress. Control means for pressing the second dressing tool against the polishing pad after the tool is pressed against the polishing pad ;
A polishing apparatus comprising: The polishing apparatus according to claim 3, wherein
Further comprising a holder for holding the first and second address tool together with the workpiece,
It said moving means further said workpiece and the polishing apparatus characterized by Ru gives a relative movement between the polishing pad.

Images