JP2002064074A - Substrate polishing apparatus and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing apparatus for polishing two sheets of substrates simultaneously with use of a single polishing platen by nearly the same polished amount for the two substrates. SOLUTION: In the apparatus for polishing two sheets of substrates at their surfaces simultaneously, the two substrates w1 and w2 held on respective heads 25 and 25 are pushed against an identical polishing platen 11, and substrates and platen are slid with intervention of polishing solution 51, and the platen or heads are rocked horizontally in a reciprocative manner. A straight line connected between central point of the two substrates lies on a vertical plane including a central point of the platen, a polishing device 30 capable of moving the heads or platen in a horizontal direction vertical to the vertical plane is used to measure polished amounts t1 and t2 for the substrates w1 and w2 for test polishing. In actual polishing, the platen or heads are moved in their rocking center so that one of the substrates held to one of the heads holding the substrate with a smaller polishing amount comes closer to an outer peripheral side of the platen, and then polishing is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method for obtaining polished substrates having substantially the same amount of polishing when two substrates are simultaneously polished with the same polishing platen, and a polishing apparatus used therefor. As the substrate, a silicon substrate, a liquid crystal substrate,
An AlTiC substrate, a resin substrate, a glass substrate, or the like can be used.

[0002]

2. Description of the Related Art It is known that a plurality of substrates are simultaneously polished with the same polishing platen in order to improve productivity (Japanese Patent Laid-Open Nos. 2000-52237 and 2000-94).
No. 317). Japanese Patent Application Laid-Open No. 2000-94317 discloses a base 1 in which three polishing platens 2a, 2b, 2c are arranged on the same circumference C as shown in FIGS.
And a separate spindle 24,
Four chuck mechanism 6a for holding a substrate two w _1, w ₂ to the head 25 which is journalled in the 24, 6b, 6c, the index head 5 formed by supporting 6d rotatably, cassette 7a, from 7b A substrate receiving table on which a transferred substrate w before polishing and a polished substrate transferred from the chuck mechanism are placed, and a pedestal cleaning mechanism 13; To the polishing platen, while interposing the polishing liquid between the substrate and the platen,
A polishing apparatus that polishes a substrate surface by sliding a substrate and a polishing platen is disclosed.

In this polishing apparatus, two substrates w ₁ and w ₂
Are located in the vertical plane including the center point of the polishing platen, and the spindles 24, 24 for bearing the heads.
Are rotated by the drive of the same motor M.

The polishing apparatus shown in FIG. 6 divides the polishing into three stages of rough polishing, medium polishing and finish polishing, and uses polishing stages 2a, 2b and 2c, respectively.
The substrates are polished simultaneously. Depending on the polishing equipment,
There may be a combination of one polishing platen and a pair of heads. Thus, polishing two substrates with one polishing platen has the advantage of improving productivity.

[0005]

Conventionally, the flatness (SFQR) of a polished substrate is determined from the management surface of the substrate in a subsequent process (backside grinding, etching, dicing, sputtering, etc.) from the flatness of the wiring width or less. Thickness is required,
The flatness (SFQR) of a conventional substrate is 0.25 μm or less, but recently, the flatness (SFQR) is 0.18 μm or less or 0.13 μm as the substrate becomes larger in diameter and highly integrated.
m or less, and a plurality of processing substrates are required to have substantially the same polishing amount satisfying these criteria.

When two substrates are polished by a single polishing platen, two substrates are caused by a slight difference in assembling accuracy of two chuck mechanisms of a polishing apparatus, a slight difference in supply of an abrasive slurry, and thermal deformation. Variations in the amount of polishing occur on the substrate held by the chuck mechanism, resulting in processed substrates having different flatnesses. If the standard required for the conventional substrate was the flatness of the substrate of 0.25 μm or less, the standard could be satisfied by changing the pressure applied to the substrate during polishing. However, when the flatness (SFQR) is 0.13 μm or less and 0.10 μm or less, it is found that the adjustment of the pressure applied to the substrate cannot be used.

An object of the present invention is to provide a polishing apparatus which provides a substrate having a polished substrate having a flatness (SFQR) of 0.18 μm or less, and a method of polishing the substrate.

[0008]

According to one aspect of the present invention, two substrates w ₁ and w ₂ held by heads each supported by a separate spindle are pressed against the same polishing platen to form a substrate and a polishing platen. A polishing apparatus for simultaneously polishing the surfaces of two substrates by reciprocatingly swinging a polishing platen or a head in a horizontal direction while sliding a substrate and a polishing platen while interposing a polishing liquid therebetween. , The two substrates w ₁ ,
a straight line connecting the center points of w ₂ is in a vertical plane including the center point of the polishing platen, there is provided a reciprocating available polishing apparatus perpendicular horizontal directions relative該鉛facing the head or polishing platen .

Since the head or the polishing platen can be moved in the horizontal direction, the polishing position is slow and the head position for holding the substrate, which tends to be thick, is swung toward the outer peripheral side of the polishing platen in accordance with the difference in the polishing amount of the substrate. Starting point of movement is 1 to 55 mm
By moving the substrate or the polishing platen while reciprocatingly oscillating, the polishing amounts of the standards W ₁ and W ₂ can be made uniform, and a polished substrate satisfying the standard of flatness of 0.18 μm or less can be obtained. can get.

[0010] Claim 2 of the present invention is directed to two substrates w ₁ , w ₁ , held on heads which are respectively supported on separate spindles.
The w _2, pressed against the same polishing platen, while the polishing liquid is interposed between the substrate and the polishing platen while sliding the substrate and the polishing platen, and, 1～55Mm width horizontally polishing platen or head A polishing apparatus for simultaneously polishing the surfaces of two substrates by reciprocating swinging, wherein a straight line connecting the center points of the _two substrates w ₁ and w ₂ is in a vertical plane including the center point of the polishing platen. In a method of manufacturing two polished substrates having substantially the same polishing amount by using a polishing apparatus capable of moving a head or a polishing platen in a horizontal plane direction perpendicular to the vertical plane, two polished substrates are experimentally polished in advance. Substrates w ₁ , w ₂
The polishing amounts t ₁ and t ₂ of the polishing platen are measured, and in the actual polishing, the substrate held by the head holding the substrate having the smaller polishing amount is brought closer to the outer peripheral side of the polishing platen. A polishing method for a substrate, characterized in that polishing is started after moving a swing center.

When the polishing platen or the head is moved so that the starting point of the substrate whose polishing amount is small is closer to the outer peripheral side of the polishing platen, the rotational speed of the outer peripheral side of the polishing platen is faster than the inner peripheral side. Is improved. The moving distance varies depending on the diameter of the substrate, the number of rotations of the head, and the number of rotations of the polishing platen, but is usually 1 to 55 mm. Determined by the number of experiments.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view of a polishing apparatus according to the present invention, and FIG.
FIG. 3 is a plan view for explaining a swing mechanism of the head of the polishing apparatus in FIG. 1, FIG. 3 is a side view of the swing mechanism, FIG. 4 is a front view of the polishing apparatus showing another embodiment, and FIG. It is a top view.

FIG. 1 shows a polishing apparatus 3 newly provided with a swinging mechanism capable of reciprocating the heads 25, 25 supported on spindles 24, 24 of the polishing apparatus shown in FIG.
0. In the figure, 1 designates a base, 2 Te - polishing platen a polishing pad 11 on the surface of the table is attached, the spindle journalled rotatably polishing platen 10, M ₄ is mode - horizontal polishing platen motor To provide a rotating driving force.

[0014] Head 25 and 25 respectively journalled in separate spindle 24, 24, adsorption or adhesion two substrates affixed by material w _1, w ₂ is maintained. Spindle 2
The rotation of the motors 4 and 24 makes the driving force of the motors M ₁ and M ₂ pulley 3
1, 31 and receive this through belts 32, 32.
This is done by notifying the users 33, 33. Numerals 34, 34 are air cylinders for raising and lowering the spindles 24, 24. 2
One of the spindles 24 and 24, swing frame - are connected by arm 35, Sa - Vomo - the drive of the motor M _3-flop - Li 36 receives, up through the belt 37 - transmitted to Li 38, ball - The screw 39 is rotated clockwise or counterclockwise (see FIGS. 2 and 3). The reversal of the spindle or the polishing platen at the time of swinging is performed by receiving a command from the control device and receiving the servo motor M _3.
Do.

The swing frame 3 is attached to the ball screw 39.
A box 40 for locking the frame 5 is screwed, and guides 41, 41 attached to the upper and lower sides of the frame 35 are rails 42.
By traveling above, the spindles 24, 24 move simultaneously in the same direction and horizontally. Limit switch LS _1, LS ₂ is provided divided into left and right a box body, illustrated dog does not comes into contact with any of the limit switch LS _1, LS ₂ when stroke - command-end is transmitted.

Reference numeral 50 denotes a polishing liquid supply nozzle. A straight line L connecting the center points of the _two substrates w ₁ and w ₂ is in the vertical plane including the center point o of the polishing platen. In FIG. 1, the center point of each of the _two substrates w ₁ and w ₂ is shown. Is drawn at a position equidistant from the center point o of the polishing platen. Spindle 2
The heads 25, 25 bearing the bearings 4, 24 are reciprocally movable in a horizontal plane direction (direction of an arrow) perpendicular to the vertical plane.

Using the polishing apparatus 30, two substrates w ₁ and w ₂ held by heads 25 and 25 respectively supported on separate spindles 24 and 24 are pressed against the same polishing platen 2 to While the polishing liquid 51 is interposed between the substrate and the polishing platen, the substrate and the polishing platen are slid to simultaneously
To polish the surfaces of two substrates, two substrates w ₁ and w ₂
The polishing conditions for actual polishing (for example, when the rotation speed of the spindles 24, 24 is 30 to 10), with each of the center points of the above being set at positions equidistant from the center point o of the polishing platen.
0 rpm, the rotation speed of the polishing platen 30 to 100 rpm,
Pressing of substrate against polishing platen 50-400 g / cm
^2, tentatively polished by polishing selected condition time 2-10 minutes), to measure the amount of polishing t _1, t ₂ test polished two substrates w _1, w _2, a polishing of the production Is such that the substrate held by the head holding the substrate with the smaller polishing amount is closer to the outer peripheral side of the polishing platen (away from the center point o of the polishing platen), and the substrates w ₁ and w ₂ Distance at which the difference between the polishing amounts t ₁ and t ₂ is eliminated, for example, 1 to 1
After the 55 mm width swing frame is moved, actual polishing (sliding the substrate and the polishing platen and reciprocating the polishing platen or the head in the horizontal direction) is started.

The moving distance for moving the oscillating frame depends on the diameter of the substrate, the number of rotations of the head, and the number of rotations of the polishing platen, but is usually 1 to 55 mm, preferably 1 to 55 mm.
A moving distance which is 20 mm and which is as small as possible as far as the difference in the amount of polishing between the two substrates w ₁ and w ₂ is obtained is determined by an experiment.

During polishing, reciprocating the head or the polishing platen in the horizontal direction reciprocally satisfies good flatness and
It is useful for obtaining a mirror-polished substrate. The distance of the reciprocating swing of the swing frame in the left-right direction during polishing is 1 to 55 mm width, preferably 25 to 50 mm. The reciprocating movement of the oscillating frame in the left-right horizontal direction causes the spindles 24, 24 holding the substrates provided in the oscillating frame to reciprocate in the left-right horizontal direction. The substrate held by the moved head also reciprocates in the horizontal direction. The position at which the substrate is reciprocally oscillated is corrected such that the oscillating frame is moved based on the difference in the polishing amount of the polished substrate obtained by polishing the substrate in the test polishing with the reciprocating oscillating condition. The starting position is the swing starting point.

In the polishing apparatus 30 shown in FIG.
4 and 24 are moved and reciprocally oscillated, but the polishing platen may be moved and reciprocally oscillated as in the polishing apparatus 30 shown in FIGS. Alternatively, the rotation of the two spindles 24, 24 may be performed by _one motor M1. Further, the heads 24, 24 and the polishing platen 1
Both of them may be designed to be able to move horizontally and swing back and forth.

Examples of the polishing cloth for the polishing platen include hard foamed urethane sheet, polyfluoroethylene sheet, polyester fiber nonwoven fabric, felt, polyvinyl alcohol fiber nonwoven fabric, nylon fiber nonwoven fabric, and foamable urethane resin on these nonwoven fabrics. A solution obtained by casting a solution, followed by foaming and curing is used. The polishing cloth may contain 1 to 35% by weight of fixed abrasive grains. As abrasive grains, the particle size is 0.0
Abrasive grains selected from silica, alumina, calcium carbonate, diamond, silicon nitride, silicon carbide, boron nitride, manganese dioxide, colloidal silica, boehmite, cerium oxide and glass powder having a size of 03 to 0.5 μm, or Two or more kinds are used in combination.

Examples of the polishing liquid vary depending on the type of the substrate, but (a) colloidal alumina, fumed silica,
0.01-20% by weight of abrasive grains such as cerium oxide, titania, colloidal silica, etc., (b) copper nitrate, iron citrate, manganese peroxide, ethylenediaminetetraacetic acid, hexacyanoiron, hydrofluoric acid, fluorotitanic acid, Oxidizing agents 1 such as dipersulfate, ammonium fluoride, ammonium hydrogen difluoride, ammonium persulfate, hydrogen peroxide, etc.
-15% by weight, (c) 0.3-3% by weight of surfactant,
A slurry containing (d) a pH adjuster, (e) a preservative, and (f) a dispersion solvent residue is used (Japanese Patent Laid-Open No. 6-3).
No. 13164, JP-A-8-197414, JP-A-8-197414
No. 510437, JP-A-10-67986, JP-A-1
No. 0-226784).

[0023]

EXAMPLE 1 26 silicon wafers having a diameter of 200 mm and a thickness of about 700 μm were polished using the simultaneous two-substrate polishing apparatus shown in FIG. Test polishing: Two substrates w ₁ and w ₂ are adsorbed to heads 25 and 25, and a colloidal silica-based abrasive slurry is applied at 50 rpm.
100r while dropping on the polishing platen rotating at m
The spindles 24, 24 rotating at pm are lowered to press the substrate against the polishing platen at a pressure of 200 g / cm ² , and the spindles 24, 24 are reciprocally oscillated at a speed of 1 cm / min in a width of 25 mm in the left-right direction. Polishing was carried out for 5 minutes. After polishing, the spindle was raised to release the suction of the head, and the polished substrate was washed with a brush, rinsed, and dried to obtain a mirror-finished substrate.

The polishing amount t ₁ of the substrate w ₁ is 2.00 .mu.m, the polishing amount t ₂ of the substrate w ₂ is 1.91Myuemu, it is towards the substrate w ₂ held by the head 25 which is journalled on the right side of the spindle it has been found polishing rate than that of the substrate w ₁ is slow.

Production polishing 1: The swing frame is moved rightward by 5 m.
m, and the head 2 is supported by the right spindle 24.
The substrate w2 held by 5 was closer to the outer peripheral side of the polishing platen than the substrate w1 held by the head 25 supported by the left spindle 24. Newly, two substrates w ₁ and w ₂ were adsorbed to the heads 25 and 25, and then polished while swinging the substrate in the left-right direction under the same polishing conditions as the test polishing described above. The resulting polishing amount t ₁ of the substrate w ₁ of the mirror-finishing is 1.95Myuemu, polishing amount t ₂ of the substrate w ₂ 1.94
μm.

Production polishing 2 to 12: For the remaining 22 substrates, except that the new spindles 24, 24 are not moved to the right by 5 mm in width, the same as in the above-mentioned production polishing 1, two by two at the same time. Polishing of the silicon wafer was performed.
The polishing amount of the obtained 22 substrates was 1.90 μm to 1.9.
It was 9 μm.

Of the 26 polished substrates, 25 having a polishing amount of 1.90 μm to 1.99 μm have a flatness of 0.
13 μm was satisfied.

[0028]

According to the method for simultaneously polishing two substrates of the present invention, a mirror-polished substrate having a small difference in polishing amount between the two substrates is provided.

[Brief description of the drawings]

FIG. 1 is a front view of a polishing apparatus according to the present invention.

FIG. 2 is a plan view illustrating a swing mechanism of a head of the polishing apparatus in FIG. 1;

FIG. 3 is a side view of the swing mechanism.

FIG. 4 is a front view of a polishing apparatus showing another embodiment.

FIG. 5 is a partial plan view of the polishing apparatus of FIG. 4;

FIG. 6 is a plan view of a known polishing apparatus.

FIG. 7 is a schematic sectional view of the polishing apparatus of FIG. 5;

FIG. 8 is a partial cross-sectional view illustrating a configuration of a head mechanism that holds a substrate.

[Explanation of symbols]

1 base plate w board M ₃ Sa - Vomo - motor 2 polishing platen 10 spindle 11 polishing cloth 24 spindle 25 head 35 swings frame - arm 39 ball - ball screw 40 box body 41 guide 42 Les - le 50 polishing liquid supply pipe 51 polished liquid

Claims (2)

[Claims] 1. A method in which two substrates w ₁ and w ₂ held by heads supported by separate spindles are pressed against the same polishing platen, and a polishing liquid is interposed between the substrate and the polishing platen. While sliding the substrate and polishing platen,
In addition, the polishing apparatus is a polishing apparatus that reciprocates and oscillates a polishing platen or a head in the horizontal direction to simultaneously polish the surfaces of two substrates, wherein a straight line connecting the center points of the _two substrates w ₁ and w ₂ is A polishing apparatus which is located in a vertical plane including a center point and is capable of reciprocating a head or a polishing platen in a horizontal plane direction perpendicular to the vertical plane. 2. A method two substrates held in each head, which is journalled in a separate spindle w _1, w _2, pressed against the same polishing platen, while the polishing liquid is interposed between the substrate and the polishing platen While sliding the substrate and polishing platen,
In addition, the polishing apparatus is a polishing apparatus for simultaneously polishing two substrate surfaces by reciprocatingly swinging a polishing platen or a head in a width direction of 1 to 55 mm, and a straight line connecting the center points of the _two substrates w ₁ and w ₂ is: Using a polishing apparatus that is located in a vertical plane including the center point of the polishing platen and that can move the head or the polishing platen in a horizontal plane direction perpendicular to the vertical plane, two polishing substrates having substantially the same polishing amount are manufactured. in the method, head in advance, the amount of polishing t _1, t ₂ pilot polished two substrates w ₁ was, w ₂ was measured, in the polishing of the production is that held the substrate towards the polishing amount is small The polishing center is started after the swing center of the polishing platen or the head is moved so that the substrate held by the polishing plate comes closer to the outer peripheral side of the polishing platen.