JP3011156B2 - CMP polishing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of manufacturing semiconductor devices, and more particularly, to a silicon oxide material layer and a metal layer (AI, AlSi, AISiCu,
The present invention relates to a CMP polishing apparatus that performs CMP polishing of AICu, Cu, W, etc.).

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become more highly integrated, the number of layers of semiconductor circuit boards has increased. 2. Description of the Related Art With the increase in the number of layers of a semiconductor circuit board, a planarization technique centering on an interlayer insulating film becomes important. Various methods are known as a technique for planarizing an interlayer insulating film. As the degree of integration of a semiconductor device increases, a planarization technique using CMP has been attracting attention.

FIG. 4A is a plan view showing a conventional CMP polishing apparatus, and FIG. 4B is a front view thereof. As shown in FIG. 4, the polishing table, a disk-shaped polishing plate 11 to match its center on the vertical axis of rotation 12 is fixed, by the rotation of the rotary shaft 12, the polishing plate 11
Rotates about the rotation shaft 12 as a center of rotation. A polishing pad 3 formed of a porous material having continuous holes is mounted on the polishing plate 11.

The wafer 13 to be polished is held on the lower surface of the wafer carrier 4, and the wafer carrier 4 is rotatably supported by a rotating shaft 5. Polished wafer 13
Is the polishing pad 3 on the polishing plate 11 via the rotating shaft 5
Pressed to. A slurry 10 as an abrasive is supplied from a slurry supply device 1 to a peripheral portion of a polishing target wafer 13 on a polishing plate 11 through a slurry supply port 2.

The conditioning disk 6 has abrasive grains such as diamond embedded in the surface thereof. By polishing the surface of the polishing pad 3,
Is to play. The conditioning disk 6 is rotatably supported at the tip of a rotary arm 7 connected to a driving device 8. The driving device 8 swings the arm 7 so that the conditioning disk 6 is rotated.
Can be moved on the polishing pad 3.

FIG. 5 shows a conditioning disk pool 9 for holding the conditioning disk 6 in a standby state. A pure water introduction pipe 16 and a pure water drain pipe 17 are connected to the conditioning disc pool tank 9, and pure water is conditioned from the pure water introduction pipe 16.
The pure water is supplied into the pooling tank 9 for the
After filling the inside of the conditioning disk pool tank 9, the water is discharged from the pure water drainage pipe 17. Conditioning disc 6 is removed from the polishing apparatus by separating the rotating arm 7 from the driving device 8, times
Conditioning condition while supported by the transfer arm 7
It is configured to be held in the pool pool 9 for a bowl.

In the polishing apparatus configured as described above,
The polished wafer 13 on which the interlayer insulating film and the like are formed is pressed against the polishing pad 3 having fine holes, and the slurry 10 is supplied between the two to polish the polished wafer 13. During the polishing, the slurry 10 is trapped in the fine holes present in the polishing pad 3, and the holes are brought into contact with the polished wafer 13 and pressed. For this reason, a fine hole is crushed or a polishing layer generated by polishing is clogged in the hole. As a result, the amount of the slurry 10 trapped in the fine holes of the polishing pad 3 decreases, and the polishing rate decreases.

Therefore, in order to reproduce or maintain fine holes in the polishing pad 3, after polishing is completed or before polishing is started,
Alternatively, the polishing pad 3 is dressed (conditioned) by the conditioning disk 6 during polishing. By this conditioning, the crushed holes in the surface layer of the polishing pad 3 are removed, the fine holes are restored, and a stable polishing rate is obtained. The conditioning disc 6 used for conditioning is immersed in pure water in the conditioning disc pool tank 9 and waits for the next conditioning.

[0009]

However, simply immersing the conditioning disc 6 in pure water in the conditioning disc pool tank 9 causes polishing debris generated by polishing on the surface of the conditioning disc 6 and the conditioning dust. There is a disadvantage that polishing pad debris is accumulated. For this reason, the protrusion amount of the diamond abrasive grains embedded in the conditioning disk 6 is reduced and the polishing rate is reduced, and the adhesion layer of the polishing debris and the polishing pad debris is peeled off from the surface of the conditioning disk 6 during dressing. Chips fall onto the polishing pad 3 and scratch the wafer 13 to be polished.
Is a problem.

[0010] As described above, in the conventional CMP polishing apparatus, firstly, the polishing dust and the polishing pad dust after polishing adhere to and accumulate on the conditioning disk 6, so that the sharpening reproducibility of the polishing pad 3 by the conditioning is improved. Has a disadvantage that the polishing rate is not stable.

Secondly, by performing conditioning while polishing dust and polishing pad dust adhered to the conditioning disk 6, the polishing dust and the polishing dust adhering to the conditioning disk 6 on the surface of the polishing pad 3 are reduced. since the polishing pad debris fall peeling, polished weather
C has a disadvantage that scratches (scratches) occur in the c .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is directed to a method of forming a material layer formed on a semiconductor substrate by CMP.
An object of the present invention is to provide a CMP polishing apparatus in which the polishing rate does not fluctuate during polishing and scratches (scratches) do not occur on a wafer to be polished during polishing, thereby improving reliability and productivity. .

[0013]

According to the present invention, there is provided a CMP polishing apparatus comprising: a polishing table on which a polishing pad is attached; a rotating device for rotating the polishing table; and a wafer on the surface of the polishing pad on the rotating polishing table. Polishing means for applying and polishing, a conditioning means for applying a conditioning disk to the surface of the polishing pad on a rotating polishing table, and a cleaning device for forcibly cleaning the surface of the conditioning disk with a brush And storing pure water
And the conditioning disk in the tank
Means for immersing the brush in pure water.
Characterized in that the brush is arranged at the bottom of the brush so as to face upward .

In this CMP polishing apparatus, the cleaning device cleans the conditioning disk with a brush.
Wash.

In this case , there is provided a tank for storing pure water, and means for immersing the conditioning disk in the pure water in the tank, and the brush is directed upward at the bottom of the tank in the tank. Are located . Further, a drive device for rotating the brush may be provided. Furthermore, an arm for rotatably supporting the conditioning disc, and a driving device for driving the conditioning disc to rotate relative to the arm are provided, and the conditioning disc is purely held in a tank via the arm. It can be immersed in water. Furthermore, means for applying ultrasonic vibration to the pure water in the tank may be provided.

In the present invention, instead of simply immersing the conditioning disc in pure water, the surface of the conditioning disc is forcibly cleaned with a brush . As described above, since the surface of the conditioning disk is actively cleaned, polishing debris and polishing pad debris adhered to the conditioning disk are reliably removed, and the protrusion amount of diamond abrasive grains embedded in the conditioning disk is reduced. Conditioning can be performed stably without polishing, and the stability of the polishing rate is improved. Further, since the polishing disc and the polishing pad debris do not adhere to the conditioning disk after the reproduction, there is no possibility that the polishing disc and the polishing disc are peeled off and foreign substances (polishing debris and polishing pad debris) adhere to the polishing pad surface. , Scratch on wafer to be polished by foreign matter
Can be prevented from occurring. For this reason, the reliability and productivity of the CMP polishing apparatus are improved.

[0017]

Next, an embodiment of the present invention will be described.
This will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a conditioning disk cleaning apparatus of a CMP polishing apparatus according to a first embodiment of the present invention. 1, the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, a driving unit (not shown) for rotating the conditioning disk 6 is provided on the conditioning disk support portion of the rotating arm 7 so as to rotate the disk 6 during cleaning. Pool tank 9 for conditioning disc
Inside, a brush 14 is installed with its brush facing upward. The brush 14 is driven to rotate about a vertical center axis by a suitable driving means. The brush 14 preferably has a brush area larger than the conditioning disk 6. Also,
At the bottom of the conditioning disk pool tank 9,
Dry air introduction pipe 15 is installed, conditionality
Dry air is blown into the pure water in the pooling tank 9 for generating bubbles to generate air bubbles.

[0018] In this embodiment apparatus constructed as above, in the polishing apparatus shown in FIG. 4, the conditioning disc 6 after conditioning the polishing pad 3 is supported on the rotating arm 7 conditionality
It is installed in the pooling tank 9 for the cooling disk . Then, the pure water is conditioned from the pure water introduction pipe 16 by conditioning.
Is supplied to the disk pool tank 9, by discharging the pure water drain pipe 17, satisfies the conditioning disk for up <br/> Lumpur tank 9 with pure water, dipping the conditioning disc 6 in pure water . Then, the conditioning disk 6 is brought into contact with the brush 14, and the conditioning disk 6 is driven to rotate by a driving unit provided on the support of the rotary arm 7.
Is rotated to print the surface of the conditioning disk 6 in a sliding manner, thereby forcibly removing polishing debris and polishing pad debris adhering to the surface. Further, when the dust removal by the brush 14, co dry air from the drying air introduction pipe 15
By blowing a pure water down di partitioning the disk pool tank 9, to generate bubbles in pure water, this bubble, rolled up debris detached from the conditioning disc 6, Jun discharged from the pure water drain pipe 17 Discharge with water.

As described above, since the conditioning disk 6 is mechanically cleaned, the polishing debris and the polishing pad debris can be reliably removed, and the diamond abrasive grains embedded in the conditioning disk 6 can be removed. Can be prevented from decreasing. As a result, the polishing pad 3 can always be stably conditioned, and the stability of the polishing rate is improved. Further, since the polishing debris and the polishing pad debris attached to the conditioning disk 6 can be reliably removed, the polishing debris and the polishing pad debris from the conditioning disk 6 are prevented from coming off on the polishing pad 3 of the polishing apparatus. Is done. As a result, there is no foreign matter (polishing debris or polishing pad debris) on the surface of the polishing pad 3 and scratches (flaws) due to the foreign substance on the wafer 13 to be polished are prevented.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be specifically described with reference to FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
This embodiment with respect to the first embodiment, that is provided with the ultrasonic generator 18 is different for applying ultrasonic vibration to the pure water in the conditioning disk pool bath 9. This ultrasonic emission
The ultrasonic wave transmitted from the creature 18 is introduced into the pure water in the conditioning disk pool tank 9 through the ultrasonic introducing pipe 19, and the pure water ultrasonically vibrates.

As described above, the cleaning effect of the conditioning disk 6 by the brush 14 is improved by vibrating the pure water with ultrasonic waves.

FIG. 3 is a schematic view showing a reference example of the present invention. In this reference example, the conditioning disc
A cleaning chamber 9a is provided instead of the pool pool 9 for use . A pure water drainage pipe 17a is provided at the lower part of the side wall of the chamber 9a.
Are connected to each other, and a plurality of pure
The water jet nozzle 21 is arranged with its jetting direction facing upward. The pure water injection nozzle 21 is connected to the pure water supply pipe 20.
The pure water is supplied to the pure water jet nozzle 21 through the pure water supply pipe 20, and the pure water is jetted upward into the chamber.

[0023] In the present embodiment, rotating the conditioning disc 6 which was subjected to the conditioning arm 7
Is inserted into the chamber 9a while being supported by
Pure water is sprayed from the pure water spray nozzle 21 toward the conditioning disk 6 above. As a result, the conditioning disk 6 is forcibly cleaned by receiving the jet of pure water, and the polishing debris and polishing pad debris adhering to its surface are reliably removed. Therefore, also in this embodiment,
The same effects as those of the embodiment shown in FIGS. 1 and 2 are obtained.

[0024]

Next, the result of actually cleaning the conditioning disk by the apparatus according to the embodiment of the present invention will be described.

Example 1 A conditioning disk was cleaned by the apparatus according to the first example of the present invention shown in FIG. Polishing conditions and cleaning conditions are as follows. The object to be polished is a P-SiO ₂ film formed on the wafer by the CVD method. <Polishing condition> Polishing plate rotation speed: 20 rpm Wafer carrier rotation speed: 20 rpm Polishing pressure: 7 psi Slurry flow rate: 100 cc / min Pure water shower flow rate: 400 L / min Polishing pad temperature: 25 ° C. <Conditioning disk cleaning condition> Conditioning disk rotation Number: 60 rpm Pure water flow rate: 2 L / min Dry air flow rate: 7 L / min As a result, the polishing rate of the P-SiO ₂ film was stabilized and the polishing uniformity was improved. In addition, scratches on the P-SiO ₂ film were also significantly reduced.

[0026] The second embodiment device of the present invention shown in Example 2. Figure 2, to be polished c
The P-SiO ₂ film formed on the wafer was polished by the CVD method under the same conditions as in Example 1, and the conditioning disk was washed under the following conditions. <Conditioner disk washing conditions> Conditioning disc rotation speed: 60 rpm pure water flow rate: 2 L / min Drying air flow: 7 L / min ultrasonic generator: 1 MHz, 100W result, a stable Similarly polishing rate as in Example 1 In addition, polishing uniformity was improved, and scratches on the wafer were significantly reduced.

[0027] Using the reference example device of the present invention as in Reference Example Figure 3, C on the wafer
The P-SiO ₂ film formed by the VD method was polished under the same conditions as in Example 1, and the conditioning disk was washed under the following conditions. <Conditioning Disk Cleaning Conditions> Conditioning disk rotation speed: 60 rpm Pure water shower flow rate: 5 l / min. As a result, as in Example 1, the polishing rate is stabilized, polishing uniformity is improved, and wafer scratches are reduced. Good results were obtained with significant reduction.

[0028]

As described above, according to the present invention,
Remove the conditioning disc after conditioning.
Since the cleaning device is provided which is immersed in pure water and forcibly cleaned with a brush , the conditioning disk can be cleaned during standby to remove polishing debris and polishing pad debris adhering to its surface. As a result, a reduction in the amount of protrusion of the diamond abrasive grains embedded in the conditioning disk is prevented, the reproducibility of dressing of the polishing pad is improved, and the polishing rate can be stabilized.

Further, always cleanliness of the surface of the conditioning disk is maintained, since the polishing debris and polishing pad debris from the conditioning disk to the polishing pad surface during the conditioning is prevented from falling peeling, scratches on the polished wafer ( Scratches) can be prevented from occurring.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conditioning disk cleaning unit of a CMP polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a conditioning disk cleaning unit of a CMP polishing apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a conditioning disk cleaning unit of the CMP polishing apparatus according to the reference example of the present invention.

FIG. 4 is a schematic view showing an example of a conventional CMP polishing apparatus, wherein (a) is a plan view and (b) is a front view.

FIG. 5 is a diagram illustrating an example of a conditioning disk cleaning unit of a conventional CMP polishing apparatus.

[Explanation of symbols]

1: Slurry supply device 2: Slurry supply port 3: Polishing pad 4: Wafer carrier 5: Rotating shaft 6: Conditioning disk 7: Rotating arm 8: Driving device 9: Pool tank for conditioning disk 9a: Cleaning chamber 10: Slurry (polishing) 11) Polishing plate 12: Rotating shaft 13: Wafer to be polished 14: Brush 15: Dry air introduction pipe 16: Pure water introduction pipe 17, 17a: Pure water drain pipe 18: Ultrasonic generator 19: Ultrasonic introduction pipe 20: pure water supply pipe 21: pure water injection nozzle

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B24B 37/00-37/04 H01L 21/304 622

Claims (4)

(57) [Claims] A polishing table to which a polishing pad is attached;
A rotating device for rotating the polishing table, polishing means for applying a wafer to the surface of the polishing pad on the rotating polishing table for polishing, and a polishing disk for applying a conditioning disk to the surface of the polishing pad on the rotating polishing table. Conditioning means for conditioning, a cleaning device for forcibly cleaning the surface of the conditioning disk with a brush , and pure water.
The storage disc and the conditioning disc
Means for dipping in pure water in a storage tank, wherein the brush is
A CMP polishing apparatus characterized in that the brush is arranged on the bottom of the storage tank with the brush facing upward . 2. The CMP polishing apparatus according to claim 1 , further comprising a driving device that rotationally drives the brush. 3. An arm for rotatably supporting the conditioning disc, and a driving device for driving the conditioning disc to rotate relative to the arm, wherein the conditioning disc is placed in a tank via the arm. The CMP polishing apparatus according to claim 1 , wherein the apparatus is immersed in pure water. 4. A CMP polishing apparatus according to any one of claims 1 to 3, characterized in that it comprises means for applying ultrasonic vibration to the pure water in the tank.