KR20040108489A - Polishing Head - Google Patents

Abstract

PURPOSE: A polishing head is provided to prevent a wafer from being damaged due to a large difference of pressure between a retainer ring and a membrane by generating properly an interlock signal using a controller. CONSTITUTION: A polishing head(300) includes a support plate(371), a membrane, a retainer ring, a measuring part, and a controller. The membrane(372) is fixed to the support plate to adsorb/pressurize a wafer. The retainer ring for preventing the deviation of the wafer is arranged to surround a periphery of the membrane. The measuring part(362) is used for measuring a first pressure value applied to the retainer ring and a second pressure value applied to the membrane. The controller(390) generates an interlock signal when the difference between the first and second pressure values deviates from a set reference range.

Description

Polishing Head

The present invention relates to a polishing apparatus for manufacturing a semiconductor wafer, and more particularly to a polishing head used in a chemical mechanical polishing apparatus.

In recent years, the structure of semiconductor devices has been multilayered with high integration. Accordingly, a polishing process for planarizing each layer of the semiconductor wafer is essentially included in the manufacturing process of the semiconductor device. Various polishing methods for performing such a polishing process have been proposed, and among them, a chemical mechanical polishing (CMP) device for chemically and mechanically polishing a wafer is widely used.

Mechanical polishing is the polishing of the wafer surface by friction between the polishing pad and the wafer surface by rotating the wafer while applying the predetermined load to the wafer while the wafer is placed on the rotating polishing pad. The surface of the wafer is polished by a slurry, which is a chemical abrasive supplied between the wafers.

As shown in FIG. 1, in a typical chemical mechanical polishing apparatus, the wafer W is mounted on the polishing head 100 so that the polishing surface faces the polishing pad, and the polishing surface of the wafer W is placed on the rotating polishing pad. The polishing head 100 provides an adjustable pressure to the backside of the wafer W and presses it onto the polishing pad.

The polishing head 100 includes a membrane 120 for pressing the wafer W and a retainer ring 140 installed around the membrane 120 to prevent the wafer from being separated from the polishing head 100 during the process. Have

The retaining ring 360 also distributes the vertical pressing force, which acts as a central portion of the membrane 120, to the peripheral portion of the polishing head 100.

Compressed air is supplied and discharged from the pressurizing means to the inner space of the polishing head 100 so that the membrane 120 moves up and down according to the pressure of the compressed air in the space.

The retainer ring 140 and the membrane 120 are moved up and down by pressure due to the injection of air, and the reference ring is set individually by measuring the pressure of the injected air.

However, only the pressure values measured at the retainer ring 140 and the membrane 120 were monitored separately, and the pressure of the retainer ring and the membrane 120 was not compared to control the progress of the polishing process when the pressure was out of the reference range. . In addition, if the wafer is broken during the polishing process, the process may be stopped to prevent the wafer from being further broken.

The present invention has been made to solve such a conventional problem, and an object thereof is to prevent cracking of a wafer when it is out of a reference range by comparing the pressure values of the membrane and the retaining ring.

1 is a schematic cross-sectional view of a conventional polishing head;

2 is a schematic diagram of a chemical mechanical polishing apparatus for explaining the present invention;

3 is a cross-sectional view showing the polishing head of the present invention.

Explanation of symbols on the main parts of the drawings

100: polishing station 110: lower post

120: table 130: delivery stage

132: base 134: head cup

140: polishing station 142: platen

144: polishing pad 146: pad adjusting device

148 slurry supply pipe 200 polishing head assembly

210: upper post 220: head support plate

222: slot 230: body

232 cover 240 drive shaft

242: driving unit 300: polishing head

310: housing 312: bushing

314: air inflow passage 316, 326: fixing device

320: pedestal 322: passage

330: gimbal mechanism 332: bend ring

334: gimbal rod 340: loading chamber

350: rolling diaphragm 352: internal clamp

354: external clamp 360: retainer ring

362: measuring unit 370: support plate assembly

371 support plate 372 membrane

373: bending diaphragm 374: upper clamp

375: lower clamp 376: support plate

380: pressure chamber 390: control unit

In order to achieve the above object, the polishing head of the present invention includes a support plate disposed below, a membrane fixed to the support plate to adsorb / press the wafer, and the membrane adsorbed to the membrane to prevent the separation of the wafer. A retaining ring disposed surrounding the outer circumferential surface thereof, a measuring unit for measuring the pressure applied to the retaining ring and the membrane, and a difference value between the pressure applied to the retaining ring and the pressure applied to the membrane is outside the set reference range. A control unit for generating a surface interlock is included.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 2 is a schematic diagram of a chemical mechanical polishing apparatus for explaining the present invention, Figure 3 is a cross-sectional view of the polishing head of the present invention.

Referring to FIG. 2, the CMP apparatus is roughly divided into a polishing station 100 and a polishing head assembly 200.

First, the polishing station 100 includes a table 120 having a lower post 110 installed at a central portion thereof, a transfer stage 130 coupled to one side of the table 120, and each polishing station 140. .

The transfer stage 130 is disposed on the base 132 and the base 132 to move the wafer W, and to load / unload the head cup loading / unloading to / from the polishing head 300 ( 134) (HCLU; Head Cup Loading Unloading).

Each polishing station 140 has a rotatable platen 142, with a polishing pad 144 disposed thereon. The platen 142 may be connected to a driving motor (not shown) located inside the table 120. In addition, the pad adjusting device 146 may be further provided to maintain the polishing conditions of the polishing pad 144, and the slurry supply pipe 148 may be provided to supply the slurry to the surface of the polishing pad 144.

On the other hand, the polishing head assembly 200 is positioned above the polishing station 100, the upper post 210 is disposed in the center is supported by the lower poster (110).

The upper post 210 is coupled to the head support plate 220, the head support plate 220 is also coupled to the body 230.

The head support plate 220 is formed with four slots 222, the slots 222 have the same separation distance from the center of the head support plate 220, are arranged at a uniform angle, the slot 222 The longitudinal direction of the) is formed in the radial direction at the center of the head support plate 220.

The drive shaft 240 connected to the polishing head 300 pressurizing the wafer W in the body 230, and the polishing head 300 rotates with respect to the drive shaft 240 in the direction of rotation of the polishing pad 144. The drive motor 242 is rotated in the same direction or in the opposite direction. In addition, the body 230 may have four covers 232 independently of each other, as shown in the figure, and may have a cover 232 for opening and closing the upper opening of one body 230.

3, the polishing head assembly 300 includes a housing 310, a pedestal 320, a gimbal mechanism 330, a loading chamber 340, a rolling diaphragm 350, and a retaining ring 360. ), And a substrate support assembly 370.

In general, the housing 310 has a circular shape so as to correspond to a circular structure of a substrate to be polished, and is fixed by a cylindrical bushing 312 coupled to the center of the housing 310, and two air inlet passages 314. The upper surface and the lower surface of the housing 310 is formed through.

In addition, the housing 310 is connected to the drive shaft 240 to rotate about the axis of the rotary table disposed perpendicular to the surface of the polishing pad 144 during the polishing process.

The pedestal 320 is a ring-shaped body positioned below the housing 310, and is preferably made of a rigid material such as aluminum, stainless steel, or reinforced plastic, and also includes a passage 322 in the pedestal 320. And a fixing device 316 or 326 is coupled to the inlet of the passage 322 and the outlet of the air inlet passage 314 of the housing 310. The fixing devices 316 and 326 are for fluidly connecting the passages by connecting a tube between the housing 310 and the pedestal 320.

The gimbal mechanism 330 is for coupling the housing 310 and the pedestal 320 such that the pedestal 320 is parallel to the surface of the polishing pad 144. The gimbal mechanism 330 is pedestal. It is provided with a gimbal rod 334 inserted through the cylindrical bushing 312 and the bent ring 332 fixed to (320). The gimbal bar 334 slides vertically along the interior of the bushing 312 to provide vertical movement of the pedestal 320, and the pedestal 320 with respect to the housing 310 prevents lateral movement.

An inner edge of the rolling diaphragm 350 is fixed to the housing 310 by an inner clamp 352, and an outer edge of the rolling diaphragm 350 is fixed to the pedestal 320 by an outer clamp 354.

In addition, the loading chamber 340 is formed between the housing 310 and the pedestal 320, the rolling diaphragm 350, and the gimbal mechanism 330 to apply downward pressure, and the polishing pad 144. The vertical position of the pedestal 320 relative to) is controlled by the loading chamber 340.

The support plate assembly 370 is largely composed of a support plate 371, a membrane 372, a curved diaphragm 373, and the like.

The support plate 371 is positioned below the pedestal 320, and includes an upper clamp 374, a lower clamp 375, and a support plate 376.

The curved diaphragm 373 has a planar annular annular shape, and an inner edge of the curved diaphragm 373 is fixed between the pedestal 320 and the retainer ring 360 described below, and an outer edge of the curved diaphragm 373. Is fixed between the upper clamp 374 and the lower clamp 375. The material is a flexible elastomer such as rubber.

The membrane 372 is a circular sheet of elastic material such as rubber, a part of which is fixed between the support plate 371 and the lower clamp 375.

A pressure chamber 380 is formed between the membrane 372, the support plate 371, the curved diaphragm 373, the pedestal 320, and the gimbal mechanism 330.

The retaining ring 360 is to prevent the wafer W adsorbed on the membrane 372 from being separated from the polishing head 300 during the process, and is disposed while surrounding the membrane 372. .

On the other hand, the membrane 372 and the retaining ring 360 is provided with a respective measuring unit 362 for measuring the pressure value.

The measuring unit 362 installed in the retaining ring 360 is for measuring the pressure applied to the polishing pad, and the measuring unit installed at the membrane 372 measures the pressure of air for vacuum adsorption of the wafer W. Measure

However, the measuring unit 362 installed in the membrane 372 is for measuring the air pressure in the loading chamber 340 and the pressure chamber 380, and the pressure chamber 380 and the loading chamber 340 inside the measuring chamber 362. It may be installed in.

The controller 390 when the pressure values measured at the membrane 372 or the loading chamber 340, the pressure chamber 380, and the retaining ring 360 deviate from a reference range set for the process. A signal is applied to generate an interlock and stop the process.

Hereinafter, the operation and effects of the polishing head which is an embodiment of the present invention configured as described above will be described.

The wafer W is vacuum-adsorbed through the loading chamber 340 and the pressure chamber 380 in communication with the air inflow passage 314 to polish the wafer W after the polishing head 300 finishes the previous process. At this time, the wafer W is accommodated in a circular space provided by the membrane 372 and the retaining ring 360.

Thereafter, the retaining ring 360 is in close contact with the upper surface of the polishing pad 144 by the driving unit of the polishing head 300 and a predetermined pressure is applied thereto. The wafer W accommodated in the polishing head 300 is in contact with the polishing pad 144 at a predetermined pressure, and at the same time, the slurry supply pipe 148 is slurry at a portion where the polishing pad 144 is in contact with the wafer W. It is then mechanically and chemically polished.

Here, when air is supplied to the pressure chamber 380 to adsorb the wafer W, the measurement chamber 362 connected to the pressure chamber 380 or the membrane 372 measures the pressure value. In addition, even when the retaining ring 360 contacts the upper surface of the polishing pad 144 and a predetermined pressure is applied, a reference pressure preferable for the measurement unit 362 connected to the retaining ring 360 to measure the pressure value and proceed with the process. If the value is out of the allowable range, an interlock is generated by the signal from the controller, and all polishing processes are stopped.

Therefore, the cracking of the wafer W due to the pressure difference caused by the interaction between the retainer ring 360 and the membrane 372 can be prevented, and it is more precise than the conventional method of monitoring each pressure individually. The polishing process can be carried out effectively.

The polishing head of the present invention as described above has the following effects.

Each measuring unit for measuring the pressure applied to the retaining ring and the membrane is provided, so that an interlock can be generated when the difference value is out of the set reference range, thereby preventing the wafer from breaking.

Claims (1)

A polishing head for use in a chemical mechanical polishing device, A support plate disposed below; A membrane fixed to the support plate to adsorb / press the wafer; A retainer ring disposed surrounding the outer circumferential surface of the membrane to prevent the wafer adsorbed on the membrane from being separated; A measuring unit measuring pressure applied to the retaining ring and the membrane; And, And a control unit for generating an interlock when a difference between the pressure applied to the retaining ring and the pressure applied to the membrane is out of a set reference range.