JP2000354958A - Work polishing device, work polishing method and manufacture for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the wafer polishing accuracy by providing a deformation correcting means for applying an external force to a work holding jig to correct deformation of a work, and continuously compensating the deformation of the work holding jig by during polishing the work, operating the work correcting means according to the detection of a work deformation detecting means. SOLUTION: Compressed air is introduced into an air chamber 14 of a toppling 10, and keeping the lower surface of a toppling base plate 10a substantially flat, a wafer 2 stuck to the lower surface of the base plate 10a is disposed opposite to the surface of a polishing pad 4, and the main surface of the wafer 2 is brought into contact with the motor-rotated polishing pad 4 to polish the wafer 2. During machining, the outputs of thermocouples 20, 21 are sampled in a fixed cycle to monitor the temperature distribution of the toppling 10. The monitoring result is collated with a control table 23 to obtain the air pressure for recovering the flatness of the lower surface of the base plate 20a, and a toppling air pressure control part 18 is controlled by a central control part 19 to press the wafer 2 to the polishing pad 4 vertically and uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for uniformly flattening one main surface of a work.
The present invention relates to a polishing apparatus for flattening a surface of an interlayer insulating film formed on a main surface of a semiconductor wafer by chemical mechanical polishing.

[0002]

2. Description of the Related Art For example, in a semiconductor device manufacturing process, the main surface of a wafer is polished with a polishing material in order to uniformly polish and flatten the surface of a wiring layer film or an interlayer insulating film deposited on a semiconductor wafer. A polishing device that performs sliding contact and polishing is used.

In a polishing apparatus applied to a semiconductor manufacturing process, it is required to polish a main surface of a wafer with high accuracy and uniformity. In particular, the interlayer insulating film deposited on the wafer is required to be polished with a film thickness distribution accuracy of 0.1 μm or less. As a polishing apparatus meeting such a demand, a polishing apparatus disclosed in Japanese Patent Application Laid-Open No. 9-7984 is known.

In the apparatus disclosed in this publication, air (air pressure) is applied directly and substantially uniformly to the back surface of a wafer so that the surface of the wafer is pressed against the rotating abrasive surface. As a result, the amount of polishing on the wafer is made substantially uniform over the entire surface.

[0005]

However, in the above-described apparatus, since the voltage is applied directly to the back surface of the wafer, the wafer may not be stably held. Vibration (dancing) can be considered.

If the air pressure is excessively applied, the holding state of the wafer becomes more unstable, and there is a limit to the pressure that can be applied.

[0007] The present invention has been made in view of such circumstances, and can stably hold a wafer.
It is an object of the present invention to provide a polishing apparatus capable of polishing a wafer with high accuracy and uniformity.

[0008]

According to a main aspect of the present invention, a work holding jig (10) for holding a work (2) and a deformation of the work (2) are provided. Deformation state detection means (20, 21, 2) for detecting the state
2), a deformation correcting means (18) for applying an external force to the work holding jig (10) to correct the deformation of the work (2), and a work (10) held by the work holding jig (10). A polishing tool (4) for polishing the workpiece (2), and the deformation detecting means (20, 21, 2, 2) while the workpiece (2) is being polished.
There is provided a workpiece polishing apparatus having a control section (19) for operating the deformation correction means (18) based on the detection of 2) and compensating for the deformation of the workpiece holding jig (10) during polishing.

According to such a configuration, the work can be performed while correcting, for example, thermal deformation of the work holding jig (top ring) generated during the polishing of the work.

According to one embodiment, the deformation state detecting means (20, 21, 22) includes the work holding jig (1).
And a temperature detector (20, 21) for detecting the temperature distribution of (0). In this case, the storage unit stores the relationship between the temperature of the work holding jig by the temperature detector and the external force applied by the deformation correction unit, and the temperature distribution detected by the temperature detection unit and stored in the storage unit. It is preferable to have a control unit that determines the external force applied by the deformation correction unit from the relationship.

According to one embodiment, the work holding jig has a hollow portion therein, and is deformed in accordance with the pressure applied in the hollow portion. Is a pressure control means for controlling the pressure to be applied in accordance with the pressure.

According to another aspect of the present invention, a work holding jig for holding a work, a deformation state detecting means for detecting a deformation state of the work, and an external force acting on the work holding jig, A workpiece polishing method for polishing a workpiece using a workpiece polishing apparatus having a deformation correction means for correcting the deformation of the workpiece and a polishing tool for polishing the workpiece held by the workpiece holding jig, A polishing step for operating the deformation correcting means based on the detection of the deformation detecting means during the polishing, thereby compensating for the deformation of the work holding jig during the polishing. .

According to still another aspect of the present invention, a step of holding a wafer on a wafer holding jig, and a step of pressing a surface of the wafer held by the wafer holding jig against a polishing tool to grind the workpiece. Detecting the temperature of the wafer holding jig during the polishing of the wafer; and compensating for the thermal deformation of the wafer holding jig based on the temperature detection of the holding jig during the polishing of the wafer. And a method for manufacturing a semiconductor device, comprising:

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a wafer polishing apparatus 1 used in a method of manufacturing a semiconductor device according to an embodiment of the present invention.
Of the main part of FIG.

The polishing apparatus according to the present embodiment performs chemical mechanical polishing (Chemical mechanical polishing) on the surface of an insulating film or a metal film formed on the main surface (lower surface) of a semiconductor wafer (shown in FIG. 2) as a work.
By mechanical polishing (hereinafter referred to as “CMP”), the surface irregularities are flattened.
Although not shown, an orientation flat is formed on a part of the outer periphery of the semiconductor wafer 2 to be polished, and a semiconductor element (for example, a memory or the like) is formed in a front region thereof. On the front surface of this memory, a wiring formed from a wiring layer film (metal film) and an interlayer insulating film (insulating film) are provided.

Here, since the wiring is formed by a line segment having a thickness, an uneven portion is formed on the surface of the interlayer insulating film adhered thereon so as to follow the unevenness of the underlying wiring. ing. Therefore, in the present embodiment, the surface of the interlayer insulating film is planarized by polishing and removing a part of the convex portion of the interlayer insulating film by the wafer polishing apparatus 1.

As shown in FIG. 1, the polishing apparatus 1 has a tool holding portion 5 for holding a polishing pad 4 (polishing cloth) on an upper surface thereof, and a state in which a main surface of a wafer 2 faces the polishing pad 4. And a head 7 to be held.

First, the tool holder 5 has a base plate 8 (surface plate) formed in a disk shape having a radius sufficiently larger than the diameter of the wafer 2. The base plate 8 is rotatably supported around a vertical axis L in a horizontal plane. The polishing pad 4 is adhered on the upper surface of the base plate 8 with a uniform thickness. The polishing pad 4 is, for example, a polishing material in which fine abrasive grains such as colloidal silica are held in a cloth (cloth) of a synthetic resin having a surface having a pore structure.

In the polishing operation using the polishing pad 4, an etching solution (a polishing solution called slurry).
Hereinafter, it is referred to as “slurry”. ) Is used, and in addition to mechanical polishing (polishing), mechanochemical polishing (mechanochemical polishing) that enhances the polishing effect
polishing) is performed. Therefore, a slurry supply nozzle (not shown) for supplying a slurry is provided directly above the center of the polishing pad 4.

On the other hand, the head 7 has a top ring 1 to which the wafer 2 is attached with the interlayer insulating film side facing down.
0, a top ring holding section 11 for holding the top ring 10 via an airbag 15, and a head shaft 12 for holding the top ring holding section 11.

The top ring 10 includes a bottom plate 10a having a diameter slightly larger than the diameter of the wafer 2, a top plate 10b formed to have substantially the same diameter as the bottom plate 10a, and a bottom plate 1a.
0a and a peripheral wall 10c connecting the peripheral portions of the top plate 10b and defining an air chamber 14 therebetween. The top ring 10 is vertically and elastically held by the top ring holding portion 11 via a diaphragm 16 that partitions the air bag 15. The top ring 10 has a central portion on the top plate 10b.
Air introduction pipe 17 for introducing air into the air chamber 14
Is connected.

This air introduction pipe 17 is connected to a top ring air pressure control unit 18. The top ring air pressure controller 18 is, for example, a pump driven by a stepping motor and a regulator for controlling air pressure. The top ring air pressure controller 18 continuously and variably controls the air pressure in the top ring 10 in accordance with a command from the central controller shown in FIG. 19, thereby forming the curvature of the lower surface of the bottom plate 10a of the top ring 10. Can be controlled.

That is, for example, when thermal expansion occurs in the bottom plate 10a due to frictional heat during polishing, the bottom plate 10a
Attempts to deform in a direction that reduces the curvature of the bottom surface. In such a case, by controlling the air pressure in the air chamber 14, a pressure is applied to the bottom plate 10a to compensate for the deformation, and the curvature of the bottom plate 10a is almost infinite, that is, The lower surface of the bottom plate 10a is always kept at a high flatness.

The top plate 10b of the top ring 10
And a bottom plate 10a, a thermocouple 2 for measuring a temperature distribution.
0 and 21 are provided. The outputs from the thermocouples 20 and 21 are input to a top ring temperature detecting unit 22, converted into a temperature signal, and input to a central control unit 19. The central control unit 19 has a control table 23 storing the relationship between the temperature distribution measured by the thermocouples 20 and 21 and the air pressure to be applied to maintain the flatness of the bottom plate 10a of the top ring 10. The central control unit 19 determines the air pressure to be applied to the top ring 10 based on the temperature distribution received from the top ring temperature detection unit 22.

That is, the bottom plate 10a of the top ring 10
Of the top ring 10 itself, which is mainly caused by frictional heat during polishing, and the top plate 10b and the bottom plate 10a
This is due to the difference in thermal expansion of Therefore, for example, an air pressure required to maintain the flatness of the bottom plate 10a of the top ring 10 at a predetermined temperature is obtained in advance by an experiment, for example, and stored in the control table 23.

Thus, the central control unit 19 controls the top ring 1 by frictional heat generated during polishing of the wafer 2.
Thus, the air pressure in the top ring 10 can be controlled so as to compensate for the thermal deformation of the bottom plate 10a and to keep the lower surface of the bottom plate 10a always flat.

The top ring 10 is preferably assembled by fixing a top plate 10b to an integrally formed product of the bottom plate 10a and the peripheral wall 10c. Also, at least the bottom plate 10 of the top ring 10
The preferred material for a is an aluminum material,
The top plate 10b may be formed of the same material as the bottom plate 10a, or may be formed of a material having a smaller coefficient of thermal expansion than the bottom plate 10a.

It is preferable that the direction of deformation of the bottom plate 10a due to thermal expansion is restricted to either the convex direction or the concave direction. For example, when the inside of the air chamber 14 is at atmospheric pressure, as shown in FIG. 2A, the bottom plate 10a is formed in a concavely curved shape, and in the initial state, as shown in FIG. As shown in (1), compressed air is introduced into the air chamber 14 to deform the lower surface of the bottom plate 10a in a convex direction so as to be formed substantially flat. In this case, when the bottom plate 10a thermally expands, the bottom plate 10a is always deformed in the concave direction.

By doing so, the rigidity of the top ring 10 during polishing can be improved, and the center of the amplitude due to the deformation can be set so that the bottom plate 10a is flat. Even when thermal deformation occurs, the flatness of the lower surface can be stably maintained with high accuracy.

As shown in FIG. 1, an air inlet 25 for controlling the air pressure in the air bag 15 is connected to the top ring holding portion 11 for holding the top ring 10. The hole 25 is connected to an airbag air pressure control unit 26. The airbag air pressure control unit 26 includes, for example, a pump and a regulator.

FIG. 3 is an overall configuration diagram of a polishing apparatus including the essential parts of the present invention described above. The head 7 is held by a Z drive mechanism 29 that drives the head 7 in the Z direction and a linear drive table 30 that drives the head 7 in the X direction.
It is driven in the XZ direction by a command from the central control unit 19.

The base plate 8 is held by a rotation drive unit 32. The rotation drive unit 32 includes a rotation shaft 33 rotatably held via a bearing (not shown).
And a drive motor 36 for driving the rotation shaft 33 via a speed reduction mechanism including a pulley 34 and a belt 35.

The head 7 is provided at a position offset from the center axis of the rotating shaft 33. By rotating the rotating shaft 33, the polishing pad 4 can be brought into sliding contact with the lower surface of the wafer 2. .

A dresser 38 for dressing the surface of the polishing pad 4 and restoring the polishing force of the polishing pad 4 is provided at a position shifted from the head 7 by 180 degrees around the central axis L. Have been. The dresser 38 includes the linear drive table 30 and the Z drive mechanism 3.
The polishing pad 4 is dressed by being activated by a predetermined time.

Next, the operation of this device will be described.

First, the central control unit 19 introduces compressed air into the air chamber 14 of the top ring 10, and holds the lower surface of the bottom plate 10a of the top ring 10 substantially flat (see FIG. 2B). ). In this state, the linear drive table 30 and the Z drive mechanism 29 operate, and the head 7
Is moved to a loading station (not shown) for discharging the wafers 2 one by one, and the wafers 2 are adhered to the lower surface of the bottom plate 10a.

Then, the wafer 2 is placed on the polishing pad 4
Face the surface of Then, with the polishing pad 4 being rotated by the motor 36 via the rotating shaft 33, the head 7 is driven downward to bring the main surface of the wafer 2 into contact with the polishing pad 4. As a result, the wafer 2
Polishing is started.

The pressing force of the wafer 2 on the polishing tool during the polishing process is performed by the central control unit 19 controlling the air pressure in the airbag 15. In addition, by supplying the slurry from the above-described slurry supply nozzle (not shown) to the polishing surface, mechanochemical polishing that enhances the polishing effect is performed in addition to mechanical polishing (polishing).

During such polishing, frictional heat is generated, and this heat is transmitted to the top ring 10 on the head 7 side via the wafer 2. By this, this top ring 10
Undergoes thermal expansion, the amount of thermal expansion and the top plate 10b and the bottom plate 10
a holding the wafer 2 due to a difference in thermal expansion from the bottom plate 1
0a is about to be deformed. The central control unit 19 includes:
Through the thermocouples 20 and 21, the thermocouples 2 are arranged at a constant cycle.
The temperature distribution of the top ring 10 is monitored by sampling the outputs 0 and 21.

Then, the central control unit 19 obtains the air pressure for restoring the flatness of the lower surface of the bottom plate 20a by comparing the temperature distribution information with the control table 23. The top ring air pressure controller 18 is controlled.

As a result, the main surface of the wafer 2 is vertically and uniformly pressed against the polishing pad 4, so that the polishing amount is uniform over the entire surface. As a result, wafer 2
Since the surface portion of the interlayer insulating film is uniformly polished over the entire surface, the uneven portion is removed over the entire surface, and the interlayer insulating film having a uniform thickness over the entire surface is formed. It is possible to realize smooth flattening.

That is, according to the present invention, since the flatness of the lower surface of the top ring can be controlled in real time during polishing, there is an effect that higher precision polishing can be performed.

The present invention is not limited to the above-described embodiment, but can be variously modified without changing the gist of the invention.

For example, the head 7 is placed on the polishing pad 4
The head 7 may be arranged on the lower side, and the polishing pad 4 may be arranged on the upper side. The configuration is not limited to lowering the head 7 side, but may be configured to raise the polishing pad 4 side. Further, the head 7 and the polishing pad 4 may be immovable in the vertical direction, and the surface to be polished of the wafer and the abrasive material surface of the polishing pad 4 may be relatively horizontally moved and simply rubbed. .

The work of the polishing apparatus is not limited to the wafer 2 having a surface coated with a metal film and an insulating film, but may be a wafer 2 before processing. That is, the wafer polishing apparatus can be used as a wafer grinding apparatus, a polishing apparatus, or the like.

On the other hand, in the above-described embodiment, a thermocouple is used as the deformed state detecting means of the top ring 10, but the present invention is not limited to this, and a direct displacement measuring device may be used. In addition, air pressure is used to correct the deformation of the top ring. However, the present invention is not limited to this. For example, a fluid such as water is sealed in the space portion 14, and The top ring 10 may be deformed by the applied pressure.

Further, in the above description, the case where the polishing apparatus is applied to the polishing of a wafer has been described. However, the present invention is not limited to this. It can be applied to polishing for polishing the surface of an object.

Further, according to such a configuration, the lower surface of the top ring can be deformed into an arbitrary convex or concave shape, so that not only planar polishing but also concave spherical and convex spherical polishing can be performed with a single top ring. Can also be performed.

[0049]

According to the above-described structure, it is possible to provide a polishing apparatus which can stably hold a wafer and can polish a wafer with high accuracy and uniformity.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a deformed state of a top ring.

FIG. 3 is a schematic configuration diagram showing an entire polishing apparatus according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wafer polishing apparatus 2 ... Semiconductor wafer (work) 4 ... Polishing pad (polishing tool) 5 ... Tool holding part 7 ... Head 8 ... Base plate 10 ... Top ring (Work holding jig) 10a ... Bottom plate (Work holding jig 10b ... Top plate 10c ... Peripheral wall 11 ... Top ring holding part 12 ... Head shaft 14 ... Air chamber (hollow part, deformation correction means) 15 ... Air bag 16 ... Diaphragm 17 ... Air introduction pipe 18 ... Top ring air pressure control part (Deformation correction means) 19 Central control unit 20a Bottom plate 20.21 Thermocouple (deformation detection means) 22 Top ring temperature detection unit (deformation detection means) 23 Control table (storage unit) 25 Air inlet 26 ... air bag air pressure control unit 29 ... Z drive mechanism 30 ... linear drive table 31 ... surface plate 32 ... rotation drive unit 33 ... rotation shaft 34 ... pulley 5 ... belt 36 ... drive motor 38 ... dresser 39 ... Z drive mechanism

Continued on the front page F term (reference) 3C058 AA07 AA09 AB04 AB09 AC02 BA01 BA05 BA07 BA08 BB02 BB04 BB08 BB09 BC02 CB01 DA17 5F033 QQ48 XX01

Claims (6)

[Claims] 1. A work holding jig for holding a work, a deformation state detecting means for detecting a deformation state of the work, and a deformation correcting means for correcting the deformation of the work by applying an external force to the work holding jig. A polishing tool for polishing the work held by the work holding jig; and during the polishing of the work, the deformation correction means is operated based on the detection of the deformation detection means, and the work holding jig being polished. And a controller for continuously compensating for deformation of the workpiece. 2. The polishing apparatus according to claim 1, wherein said deformation state detecting means includes a temperature detector for detecting a temperature of said work holding jig. 3. The polishing apparatus according to claim 2, wherein the storage unit stores a relationship between a temperature distribution of the work holding jig by the temperature detector and an external force applied by the deformation correction unit. A workpiece polishing apparatus, comprising: a control unit that determines an external force to be applied by the deformation correction unit from a detected temperature distribution and a relationship stored in the storage unit. 4. The polishing apparatus according to claim 1, wherein the work holding jig has a hollow portion therein, and is deformed according to a pressure applied in the hollow portion. Is a hollow chamber pressure control means for controlling a pressure applied according to deformation. 5. A work holding jig for holding a work, a deformation state detecting means for detecting a deformation state of the work, and a deformation correcting means for correcting the deformation of the work by applying an external force to the work holding jig. And a work polishing method for polishing a work using a work polishing apparatus having a polishing tool for polishing a work held by the work holding jig, wherein during the polishing of the work, the deformation detection means A method of polishing a work, comprising: activating the deformation correction means based on the detection to compensate for deformation of the work holding jig during polishing. 6. A step of holding a wafer on a wafer holding jig; a step of pressing a surface of the wafer held by the wafer holding jig against a polishing tool to polish the workpiece; A semiconductor comprising: a step of detecting a temperature of the wafer holding jig; and a step of compensating for thermal deformation of the wafer holding jig based on the temperature detection of the holding jig during polishing of the wafer. Device manufacturing method.