JP2001351884A - Chemical mechanical polishing apparatus for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing apparatus having a long life of polishing pads and short throughput time which can provide a CMP- processed substrate having a good flatness and less dishing and erosion. SOLUTION: The chemical mechanical polishing apparatus is used for removing at least part of a metal film or insulation film on the surface of a substrate by swinging the abrasive pads back and forth like a pendulum around a rotary shaft 6 in the horizontal direction on a substrate, while vacuum chucks 12a, 12b, 12c, 13d holding the substrate and the abrasive pads are caused to slide on each other. The diameter of the abrasive pads is smaller than that of the substrate. Each of the vacuum chucks for holding the substrate comprises a suction board disposed at the center to hold the substrate and an annular guide board 18 surrounding the periphery of the substrate. The annular guide board has nearly the same thickness as that of the substrate to be chucked, and the surfaces of the annular guide board and substrate become flushed with each other when the substrate is chucked. In the surface of the annular guide board to be flushed with that of the substrate, a plurality of recesses 19 communicating from the inner to outer edges are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad having a diameter smaller than the diameter of a substrate.
When performing chemical mechanical polishing by polishing, the polishing pad comes to the outer peripheral edge of the substrate and tilts, and the edge (edge) of the obtained polishing substrate is excessively polished and becomes thinner than the center,
Conversely, it is possible to provide a substrate having excellent uniformity of the thickness distribution, which can prevent the edge polishing from being insufficient and becoming too thick from the central portion to prevent the thickness distribution of the polished substrate from becoming uneven. The present invention relates to a chemical mechanical polishing apparatus that can be used. The chemical mechanical polishing apparatus according to the present invention includes the steps of: removing a metal film formed on an insulating layer of a substrate; removing an insulating layer film on a substrate surface provided with an insulating layer film on a pattern pattern of the metal film; STI (Shallow T
This is useful for removing a P-TEOS layer of a trench insulator (rench insulator).

[0002]

2. Description of the Related Art A plurality of polishing pads axially symmetrically mounted on a single spindle shaft are used. A polishing slurry is supplied from the center of the polishing pad to press a substrate held by a chuck into contact with the pad. Chemical mechanical polishing (CMP polishing) of a substrate by rotating and sliding the substrate in the same direction or in the opposite direction, and linearly reciprocating a spindle shaft supporting a plurality of polishing pads on the substrate. The device is known (JP-A-8-277160, USP 593).
1722, US Pat. No. 5,934,799).

As shown in FIG. 5, US Pat. No. 5,931,722.
The chemical mechanical polishing apparatus 100 disclosed in Japanese Patent Application Laid-Open Publication No. H10-207702 linearly reciprocates a plurality of polishing pads 102, 102 having a small diameter of 1/5 to 1/10 of the diameter of the substrate on a substrate w held by a chuck 101. When chemical mechanical polishing is performed by moving the polishing pad, the polishing pad comes to the outer peripheral edge of the substrate and tilts, and the edge (edge) of the obtained polishing substrate is excessively polished and becomes thinner than the center. An annular dummy plate surrounding the outer edge of the substrate w held by the vacuum chuck 101 is used as a means for preventing the thickness of the substrate from becoming insufficient and becoming excessively thicker than the central portion so that the thickness distribution of the polished substrate becomes uneven. The height 103 is such that the surface of the dummy plate and the chuck surface are flush with each other, and a gap 104 of 1 to 3 mm is provided between the inner edge of the dummy plate and the outer peripheral wall of the substrate. A radial groove 105 is provided between the back surface of the dummy plate and the chuck surface to facilitate discharge of the abrasive slurry 107 supplied from the hollow portion of the spindle shaft 106 and used for CMP polishing of the substrate.

In the chemical mechanical polishing apparatus 100, a plurality of rotatable polishing pads 102, 102 are arranged symmetrically with respect to a single hollow spindle shaft 108 which can reciprocate in a linear manner. There is an advantage that the surface of the substrate polished by the CMP using a plurality of polishing pads reciprocating in the horizontal direction and the front-rear direction becomes a mirror surface with no streaks.

[0005]

However, since a plurality of polishing pads are arranged symmetrically with one hollow spindle shaft 108 as a symmetric axis, the rotational vibrations of the polishing pads affect each other during CMP polishing. , Obtained CM
The flatness (Non-Uniformity), dishing, and erosion of the P-processed substrate are not satisfactory values. Further, since the diameter of the polishing pad is smaller than the diameter of the substrate, there is a disadvantage that wear is fast. SUMMARY OF THE INVENTION The present invention provides a chemical mechanical polishing apparatus that provides a CMP-processed substrate that is excellent in flatness (Non-Uniformity), dishing, and erosion with little wear of a polishing pad.

[0006]

According to one aspect of the present invention, there is provided a vacuum cleaner.
Holding the substrate with the metal film surface or the insulating film surface of the substrate facing upward on the chuck, and polishing the surface of the polishing pad attached to a mounting plate supported on a spindle shaft having a vertical axis with respect to the substrate by an abrasive. The polishing pad is pressed against the substrate through the liquid, and the polishing pad and the vacuum chuck holding the substrate are slid, and the polishing pad is reciprocally swinged in a horizontal direction on the substrate about the rotation axis. A chemical mechanical polishing apparatus used to remove at least a part of the metal film or the insulating film on the substrate surface, wherein the polishing pad diameter is smaller than the diameter of the substrate, and the chuck holding the substrate is located at the center. A suction plate for holding the substrate; and an annular guide plate surrounding the periphery of the substrate. The thickness of the annular guide plate is substantially the same as the thickness of the substrate to be chucked, and both surfaces are flush with each other in a state where the substrate is chucked. At a height The annular guide plate is provided on the vacuum chuck so as to rotate in the same direction and direction as the rotation of the suction plate, and the surface of the annular guide plate, which is flush with the surface of the substrate, extends from the inner edge. An object of the present invention is to provide a chemical mechanical polishing apparatus, wherein a plurality of grooves leading to an outer edge are provided.

Since a plurality of grooves are provided on the surface of the annular guide plate which is flush with the surface of the substrate, the area of contact between the polishing pad and the guide plate is reduced, so that the amount of wear is small, and Long life. Further, the abrasive slurry is easily discharged out of the chuck along the groove. Further, no streaks are generated on the substrate surface due to the reciprocating oscillation (Oscillation) of the polishing pad. In addition, by making the polishing pad diameter smaller than the substrate diameter, the polishing state of the metal layer and the insulating layer of the substrate can be visually observed during the CMP polishing, and the thickness of the substrate can be measured with a laser sensor, or the color identification sensor can be used. The polishing state can be observed with a color identification camera, and the end point of polishing can be easily detected.

According to a second aspect of the present invention, in the chemical mechanical polishing apparatus, the outer diameter of the polishing pad is 1/2 to the diameter of the substrate.
The reciprocating swing trajectory of the polishing pad is 3/4, and is characterized by an arc shape passing through the center of the substrate and exceeding the outer periphery of the substrate.

The outer diameter of the polishing pad is 1/2 to the diameter of the substrate.
Since the polishing pad diameter is 3/4 times larger than the diameter of the polishing pad of 1/5 to 1/10 times described in the above-mentioned patent publication, the area in contact with the substrate is increased, and the polishing time can be reduced.

According to a third aspect of the present invention, in the chemical mechanical polishing apparatus, the vacuum chuck provided with the annular guide plate is provided on the index table at equal intervals around the rotation axis of the index table. There are provided six or six polishing pads, and two or three polishing pads capable of reciprocating pendulum movement are provided.

By using a chemical mechanical polishing apparatus having an index type structure using a plurality of polishing pads and a chuck mechanism, the throughput time can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 shows a vacuum table in the index table.
FIG. 2 is a perspective view of a chemical mechanical polishing apparatus provided with four vacuum chucks, FIG. 2 is a plan view of an index table provided with four vacuum chucks with an annular guide in FIG. 1, and FIG.
Is a partial sectional view showing a positional relationship among a polishing head, a vacuum chuck, and a pad conditioning mechanism of the chemical mechanical polishing apparatus shown in FIG. 4, and FIG. 4 is a partial sectional view of the polishing head.

In the index type chemical mechanical polishing apparatus 1 shown in FIGS. 1 and 3, 2 is a polishing head, 2a is a polishing head for coarse polishing, 2b is a head for finish polishing, 3, 3 is a spindle shaft, and 3a is a motor. Gear, 3b gears, 3c gears
Re, 3d is a gear, 4 is a polishing pad, 5, 5 is a pad conditioning mechanism, 5a is a dressing disc,
5b is a protective cover, 5c is a cleaning brush, 6 and 6 are a pendulum rotation drive mechanism of the polishing head, 6a is a rotary table, 6b is an arm, 6c is a rotating shaft, and 7 is a polishing head protection housing. Reference numeral 8 denotes an air cylinder as a head elevating mechanism. Reference numeral 9 denotes a wafer storage cassette. Reference numeral 10 denotes a loading / transporting robot. Reference numeral 11 denotes a temporary wafer placement table. Reference numeral 12 denotes a shaft 12e having an axis of 90 on the same circumference c1. Four rotatable wafer chuck mechanisms 12a, 12 provided at equal intervals by degrees
an index table comprising b, 12c, 12d,
As shown in FIG. 2, the index table 12 is divided into a wafer loading zone s1, a rough polishing zone s2, a finishing polishing zone s3, and a wafer unloading zone s4.

13 is a transfer robot for unloading,
14a is a chuck dresser, 14b is a chuck cleaning mechanism, 15 is a temporary wafer placement table, 16 is a belt conveyor, 17
Denotes a wafer cleaning mechanism. As shown in FIG. 3, a drive shaft of a motor 12f installed below the table is connected to the rotation shaft 12e of the index table 12, and the motor 12f is driven to rotate the rotation shaft. Index table 12 is centered on each vacuum chuck table 12e.
a, 12b, 12c, and 12d are integrally rotated with each other by 90 degrees in the forward and reverse directions. When the index table is rotated, the nucleus chuck table moves along a circle c1 shown in FIG. To rotate.

In each vacuum chuck table, a hollow rotary shaft 12g is disposed in an index table, and a suction plate 12h holding a wafer w is integrally fixed to an upper end thereof, and a lower end of the rotary shaft 12g. Part is index table 1
2 is provided rotatably in connection with the drive shaft of a motor 12l installed at the lower part. The suction plate 12h is formed by forming a large number of small holes 12i on the upper surface thereof, or is formed of a porous ceramic plate. The small hole 12i of the suction plate 12h is formed inside the hollow of the rotating shaft 12g. Two utility pipes 12j and 12k that communicate with each other are inserted, and these utility pipes are connected to a vacuum pump, pure water or a battlefield station supply pump (not shown) via rotary joints 12m and 12n. It is connected.

On the upper surface of each vacuum table,
An annular guide plate 18, 18, 18, 18 is provided.
The annular guide plate surrounds the periphery of the substrate held by the suction plate, and the thickness of the annular guide plate is substantially the same as the thickness of the substrate to be chucked, and the surfaces of the annular guide plate are flush with each other when the substrate is chucked. And the annular guide plate is provided on the vacuum chuck table so as to rotate in the same direction and in the same direction as the rotation of the suction plate. A plurality of grooves 19 extending from the inner edge to the outer edge are provided on the surface of the annular guide plate 18 which is flush with the surface of the substrate.

The shape of the groove 19 is such that a width of 0.5 from the central axis 12e of the suction plate toward the outer periphery of the guide plate 19 is provided.
It may be a groove of up to 3 mm (see FIG. 2), an embossed hemispherical pattern, or a lattice-like groove. Examples of the guide plate material include an aluminum plate, a polyvinylidene fluoride plate, an ultrahigh molecular weight polyethylene plate, an epoxy resin plate, and a polytetrafluoroethylene plate. The thickness of the annular guide plate is preferably a thickness substantially flush with the surface of the substrate, and is generally preferably a thickness obtained by subtracting the thickness of the guide plate flush with the surface of the substrate by an amount to be polished.

In the polishing head 2 shown in FIG. 4, the overhanging edge 21a of the substrate 21 is
The polishing pad (polishing cloth) 4 is supported by a substrate 21 via a polishing cloth mounting plate 22. A diaphragm 23 is stretched in a pressurizing chamber 20b in the pressurizing cylinder 20, and compressed air is press-fitted into the pressurizing chamber 20b through the spindle shaft 3, and the substrate 21 is three-dimensionally (X, Y) by the pressure. , Z), and the pad 4 is held parallel to the wafer surface.

A polishing liquid or cleaning liquid supply pipe 24 is provided at the center of the polishing head 2, and the tip of the pipe faces the back surface of the polishing pad avoiding the center hollow portion 4 a of the polishing pad, and the metal of the substrate passes through the polishing pad. A polishing liquid or an etching liquid is supplied to the layer surface.

The step of polishing a wafer (substrate) having a metal film on an insulating layer using the chemical mechanical polishing apparatus 1 is performed as follows. 1) The wafer w1 is taken out of the cassette 9 by the arm of the transfer robot 10, placed on the temporary mounting table 11 with the metal film surface facing upward, the back surface thereof is cleaned, and then the index table 12 is transferred by the transfer robot. Uehara-
It is transferred to the ding zone s1 and is sucked by the chuck mechanism 12a.

2) The index table 12 is rotated clockwise by 90 degrees to rotate the wafer w1 in the first polishing zone s.
2, the spindle shaft 3 is lowered, the polishing pad 4 attached to the head 2a is pressed against the wafer w1, and the wafer is chemically and mechanically polished by rotating the spindle shaft 3 and the chuck mechanism. During this time, a new wafer w
2 is placed on the temporary table, transferred to the wafer loading zone s1, and sucked by the chuck mechanism 12b. At the time of CMP processing of the wafer, one abrasive liquid is applied to the back surface of the polishing pad 4 through a supply pipe 24 provided in the hollow portion of the spindle shaft 3.
It is supplied at a rate of 0 to 100 ml / min. Chuck Tees
The rotation speed of the wafer sucked by the bull is 200 to 800 r.
pm, preferably 200 to 600 rpm, and the rotation speed of the polishing pad is 400 to 3000 rpm, preferably 400 to 3000 rpm.
1000 rpm, pressure applied to the substrate is 1.2 to 3 psi
It is.

During the CMP process, the arm 6b fixed to the shaft 6c reciprocates by rotating the shaft 6c of the polishing pad 4 by the pendulum rotating mechanism 6. The reciprocating swing trajectory of the polishing pad 4 is an arc passing through the center of the substrate and exceeding the outer periphery of the substrate.

When the chemical mechanical polishing in the first polishing zone s2 has been performed for a desired time, the spindle shaft 3 is raised and the arc is removed.
Conditioning cleaning mechanism 5 by rotating the pad
Guide the high pressure jet water to the nozzle (not shown)
While spraying, the rotating brush 5c removes abrasive particles and metal polishing debris adhered to the surface of the front pad, and then lowers the polishing pad to contact the disk 5b, conditions the polishing pad, raises the polishing pad, and re-axes. 6c
Is rotated to transfer the polishing pad and wait on the polishing zone s2.

3) Rotate the index table 90 degrees clockwise, guide the polished wafer w1 to the second polishing zone s3, lower the spindle 3
The polishing pad 4 attached to the wafer b is pressed against the roughly polished wafer w1, and the spindle mechanical shaft and the chuck mechanism are rotated to perform the chemical mechanical finish polishing of the wafer.
After finishing polishing, the spindle shaft 3 is raised and retracted rightward, the polishing pad attached to the head 2b is cleaned by the conditioning cleaning mechanism 5, and the polishing pad is rotated again to transfer the polishing pad, and the second polishing zone is moved. -Wait on s3. During this time, a new wafer w3 is placed on the temporary mounting table, transferred to the wafer loading zone s1, and sucked by the chuck mechanism 12c. In the first polishing zone s2, the chemical mechanical rough polishing of the wafer w2 is performed.

4) The index table 12 is rotated 90 degrees clockwise to guide the polished wafer w1 to the unloading zone s4. Next, the wafer polished and finished by the unloading transfer robot 13 is placed on the temporary table 1.
5 and after cleaning the back surface, further transfer robot 13
The cleaning liquid is sprayed onto the polished wafer pattern surface from the nozzle 17 to clean the wafer, and the wafer is guided to the next step. During this time,
A new wafer w4 is placed on the temporary table, and the wafer
It is transferred to the ding zone s1 and is sucked by the chuck mechanism 12d. In the first polishing zone s2, the chemical mechanical rough polishing of the wafer w3 is performed, and in the second polishing zone s3, the chemical mechanical finish polishing of the wafer w2 is performed.

5) The index table 12 is rotated clockwise by 90 degrees, and the same operations as in the above steps 2) to 4) are repeated to perform chemical mechanical polishing of the wafer.

In the above example, the chemical mechanical polishing is divided into the first rough polishing and the second finish polishing in order to reduce the throughput time. However, the CMP may be performed in one step. Alternatively, rough polishing, medium finish polishing, and finish polishing are divided into three stages to further reduce the throughput time. When a three-step CMP process is performed, s1 is used as a wafer loading and unloading zone.
S2 is the first polishing zone, and s3 is the second polishing zone.
And s4 is a third polishing zone. It is preferable that a maximum of six chucks are provided in the index table.

The material of the polishing pad may be different from that of the first polishing pad and the second polishing pad. The abrasive slurry may also vary.

The substrate is held on a chuck table with the surface of the metal film or the surface of the insulating layer (including the surface where both are mixed) facing upward, and is mounted on a spindle shaft having a vertical axis with respect to the substrate. The surface of the polishing pad attached to the attached mounting plate is pressed via loose polishing abrasive grains (abrasive)), and the substrate and the polishing pad are slid, and the polishing pad having a smaller diameter than the substrate diameter is reciprocated on a pendulum. When chemical mechanical polishing is performed by swinging to remove at least a part of the metal film or the insulating film on the substrate surface, when the center point of the polishing pad protrudes outside the outer peripheral edge of the substrate, the polishing pad tilts. Since it is supported by an annular guide plate and keeps the polishing pad surface parallel to the substrate surface, C
The thickness distribution of the substrate polished by MP becomes uniform.

Examples of the polishing pad material include hard foamed urethane sheet, polyfluoroethylene sheet, polyester fiber non-woven fabric, felt, polyvinyl alcohol fiber non-woven fabric, nylon fiber non-woven fabric, and foamable urethane resin solution on these non-woven fabrics. What is cast, then foamed and cured is used. As the pad shape, a disk shape, a donut shape, or an elliptical shape is used, and the thickness is 3 to 7 mm.
Is used by being attached to a mounting plate such as an aluminum plate or a stainless steel plate. The outer diameter of the polishing pad is preferably か ら to ／ of the diameter of the substrate. The pendulum reciprocating speed of the polishing pad is preferably 0.5 to 3 m / min.

The abrasive liquid varies depending on the type of the substrate.
In the case of a device substrate having a metal layer and an insulating layer, (a) 0.01 to 20% by weight of solid abrasive grains such as colloidal alumina, fumed silica, cerium oxide, and titania; (b) copper nitrate and iron citrate , Manganese peroxide, ethylenediaminetetraacetic acid, hexacyanoiron, hydrofluoric acid, fluorotitanic acid, dipersulfate, ammonium fluoride,
Oxidizing agents such as ammonium hydrogen difluoride, ammonium persulfate, hydrogen peroxide, etc. 1 to 15% by weight, (c) surfactant 0.3 to 3% by weight, (d) pH adjuster, (e) preservative,
Is used (Japanese Patent Laid-Open No. 6-31).
No. 3164, JP-A-8-197414, JP-T-8-8-5
10437, JP-A-10-67986, JP-A-10-67986
226784). Abrasive slurries suitable for polishing metals such as copper, copper-titanium, copper-tungsten, and titanium-aluminum are available from Fujimi Incorporated,
Roder Nitta Co., Ltd., Cabot Corporation of the United States, Rodell Corporation of the United States, Olin Arc of the United States (Olin Arc)
h) Available from companies.

EXAMPLES Example 1 A silicon substrate having a copper film provided on a silicon oxide insulating film having a diameter of 200 mm as a substrate was used as a polishing agent, and a polishing slurry for a first step copper film of Fujimi Incorporated was used as a polishing agent (prototype product). ) At a volume of 75 ml / min.
Made of Le Polyurethane resin (Product name: IC1000)
As shown in FIG. 1, a polishing apparatus has an annular pad having an outer diameter of 110 mm, an index table, a vacuum chuck, and 72 radial grooves having a width of 2 mm (one groove at intervals of 5 degrees) on the surface. Using an automatic chemical mechanical polishing apparatus equipped with an annular guide plate (outer diameter 220 mm, inner diameter 201 mm) and a two-head polishing pad, the rotation speed of the substrate chuck table is 200 rpm in a counterclockwise direction, and the rotation speed of the polishing pad is 400 rpm in a clockwise direction. The pressure of the polishing pad applied to the substrate was set to 2.8 psi (200 g / cm ² ), the reciprocating speed of the pendulum was set to 1 m / min, and the pendulum movement width was set to an arc shape in which the pad protruded 15 mm outside the outer periphery of the substrate, and was subjected to chemical mechanical polishing for 70 seconds. Was performed.

The copper removal rate is 7230 angstroms /
Min, the non-uniformity was 2.8%. Further, the polishing pad was in a state where it was not necessary to replace the polishing pad even after chemically mechanically polishing 150 substrates.

[0033]

According to the chemical mechanical polishing apparatus of the present invention, at the time of surface chemical mechanical polishing of the substrate, the polishing pad portion deviated from the outer periphery of the substrate is supported by the annular guide plate. (Non-Uniform
(i.e., a processed substrate having an excellent substrate quality). Also,
The presence of the groove in the guide plate reduces the area of the polishing pad in contact with the guide plate, so that the wear time of the polishing pad is delayed and the service period of the polishing pad is lengthened.

[Brief description of the drawings]

FIG. 1 is a perspective view of a CMP apparatus of the present invention.

FIG. 2 is a plan view showing a positional relationship among an index table, a vacuum chuck, and a guide plate in FIG. 1;

FIG. 3 is a partial cross-sectional view showing a positional relationship among an index table, a polishing head, and a polishing pad conditioning mechanism in FIG. 1;

FIG. 4 is a partial sectional view of the polishing head in FIG. 1;

FIG. 5 is a front view of a known CMP apparatus.

[Explanation of symbols]

Reference Signs List 1 chemical mechanical polishing device w substrate 2 polishing head 3 spindle shaft 4 polishing pad 12 index table 12a, 12b, 12c, 12d vacuum chuck 18 guide member 19 groove

Claims (3)

[Claims] A vacuum chuck holds a substrate with its metal film surface or insulating film surface facing upward, and is attached to a mounting plate which is mounted on a spindle shaft having a vertical axis with respect to the substrate. The polishing pad surface is pressed against the substrate via the polishing agent liquid, and the vacuum pad holding the substrate and the polishing pad are slid, and the polishing pad is horizontally moved on the substrate about the rotation axis. A chemical mechanical polishing apparatus used to remove at least a part of a metal film or an insulating film on a substrate surface by swinging a reciprocating pendulum in a direction, wherein the polishing pad diameter is smaller than the diameter of the substrate; The vacuum chuck for holding the substrate includes a suction plate for holding the substrate at the center and an annular guide plate surrounding the periphery of the substrate. The thickness of the annular guide plate is substantially the same as the thickness of the substrate to be chucked, and the substrate is chucked. Was The annular guide plate is provided on a vacuum chuck so as to rotate in the same direction and direction as the suction plate, and is flush with the surface of the substrate. A chemical mechanical polishing apparatus, characterized in that a plurality of grooves extending from the inner edge to the outer edge are provided on the surface of the annular guide plate. 2. An outer diameter of a polishing pad is １ ／ of a diameter of a substrate.
2. The chemical mechanical polishing apparatus for a substrate according to claim 1, wherein the reciprocating swing trajectory of the polishing pad is an arc shape passing through the center of the substrate and exceeding the outer periphery of the substrate. 3. 3. A vacuum chuck having an annular guide plate is provided at three or six index tables at equal intervals on a circumference around a rotation axis of the index table, and is capable of reciprocating a pendulum. 2 or 3 polishing pads
3. The method according to claim 1, wherein the base is provided.
3. The chemical mechanical polishing apparatus for a substrate according to claim 1.