CN101007396A - Polishing head applied to chemical mechanical polishing process and chemical mechanical polishing method - Google Patents

Abstract

A polishing head for use in a Chemical Mechanical Polishing (CMP) process, comprising: a housing; a wafer edge pressing cover ring locked at a lower position of the shell; a support backplate having a plurality of non-concentric pressure zones (pressure zones) arranged therein, the support backplate having a wafer contact surface and an amorphous wafer contact surface, wherein the wafer contact surface of the support backplate abuts against a backside of a wafer during a CMP polishing process; and a pneumatic device for independently controlling the down pressure applied to the back surface of the wafer in each of the plurality of pressure zones arranged in a non-concentric circle during the CMP polishing.

Description

Be applied to the rubbing head and the cmp method of CMP process

Technical field

The present invention relates to chemically mechanical polishing (the chemical mechanicalpolishing in the semiconductor technology, be designated hereinafter simply as CMP) field, relate in particular to a kind of rubbing head (carrier head) design of novelty, can in polishing process, obtain the preferable polishing uniformity (uniformity).

Background technology

In making the process of integrated circuit, inevitably need be on a wafer stacked structure of precipitation number layer unlike material, thus, cause the concave plane of wafer surface.Irregular wafer surface will cause some photoetching process problems, for example the depth of focus (depth of focus, DOF) deficiency and image transfer deviation.Therefore, in making the integrated circuit process, just often need be with planarization, CMP technology for example, the in addition irregular surface of planarization wafer.

The CMP technology is that a polished wafer face is pressed on the polishing pad (polishing pad) down, this polished wafer is fixed by a discoid mechanism that is called rubbing head (carrier head), in the polishing stage, rubbing head drives this polished wafer and rotates with a fixed rotating shaft, polishing pad is then with another rotating shaft rotation, then by chemistry or mechanical system is able to the dielectric layer that wafer surface is to be removed or metal level polishes.More general rubbing head is a kind of design that is called unsteady (floating) rubbing head at present, it is to utilize an elastic membrane (flexible membrane) that a wafer support dish or backboard (backing plate) are fixed in pedestal below, in the polishing stage, can utilize gas pressurized on the wafer support dish, impose on the downforce (downforce) of the brilliant back of the body of wafer with average dispersion.

The problem that existing C MP technology is often met is that formation polished lip-deep pattern distribution of wafer and high low head are often also unequal, thus, cause when carrying out the CMP polishing, inhomogeneous on polishing speed on the wafer surface distributes, for example, polishing speed at the pattern density higher position is slower, and then polishing is very fast to dredge the place at pattern density.In addition, the polished material layer on the wafer surface also may present high low uneven thickness phenomenon on one side on one side, and at this moment, existing C MP technology and traditional rubbing head design promptly can't provide the effect that makes wafer surface that preferable planarization be arranged.

Summary of the invention

Main purpose of the present invention provides a kind of rubbing head (carrier head) design and cmp method of improvement, can obtain the preferable polishing uniformity in the CMP polishing process.

According to a preferred embodiment of the invention, the invention provides a kind of rubbing head that is applied to chemically mechanical polishing (CMP) technology, comprising: a housing; One Waffer edge covers ring, is locked in a lower position of this housing; One supporting back board, it has a plurality of pressure areas (pressure zone) that non-concentric circles (non-concentric) is arranged that are, and this supporting back board has a wafer contact-making surface and an amorphous sheet contact-making surface, when wherein carrying out CMP polishing, this wafer contact-making surface of this supporting back board is against living a chip back surface; And a pneumatic means, be used for when carrying out this CMP polishing independently control these a plurality of pressure that are applied to this chip back surface in the non-concentric circles line pressure district that are individually.

According to another preferred embodiment of the invention, the invention provides a kind of cmp method, comprise the steps: at least

(a) wafer is fixed on the rubbing head, wherein this rubbing head includes a pressure apparatus, and it is controlled by a control module, be used for when carrying out CMP polishing, control is applied on the back side of this wafer independently, and each is in the pressure area of non-concentric circles arrangement, individual other pressure;

(b) this rubbing head and a polishing pad are rotated, wherein this rubbing head is to be placed on this polishing pad;

(c) provide a downforce to this wafer; And

(d) material layer on this wafer is polished removal equably.

Major advantage of the present invention is can be when polishing, and rubbing head can provide an instant adjustable downforce by the design of air bag and backboard bottom, therefore can improve the polishing uniformity of wafer surface.

In order to allow above-mentioned and other purpose, feature and the advantage of the present invention can be clearer and more definite understandable, a preferred embodiment cited below particularly, conjunction with figs. elaborates.

Description of drawings

What Fig. 1 illustrated is the generalized section of chemical-mechanical polishing mathing platform of the present invention;

What Fig. 2 illustrated is the cross-sectional view of the rubbing head of the preferred embodiment of the present invention;

Fig. 3 illustrates be the preferred embodiment of the present invention supporting back board on look schematic diagram;

Look schematic diagram on another preferred embodiment supporting back board of the present invention that Fig. 4 illustrates;

What Fig. 5 illustrated is another preferred embodiment rubbing head cross-sectional view of the present invention.

The main element symbol description

50 chemical-mechanical polishing mathing platforms, 52 rubbing heads

54 wafers, 56 polishing pads

60 rotating shafts of 58 polished land

62 rotating shafts, 150 housings

152 Waffer edges coverring 154 supporting back board

156 brilliant back of thebody cushion pad 158 barrier films

Opening around 162middle openings 164

182 air bag devices, 184 air bag devices

192 pressure responsive element, 194 pressure responsive element

The specific embodiment

See also Fig. 1, what it illustrated is the generalized section of chemical-mechanical polishing mathing platform of the present invention.As shown in Figure 1, chemical-mechanical polishing mathing platform 50 of the present invention includes a rubbinghead 52, is used for fixing a wafer 54.Rubbinghead 52 is connected to a power transmission shaft and a mechanical switch arm (not shown) usually, and wherein the mechanical switch arm can transmit wafer between different polishing pads.In addition, chemical-mechanical polishing mathing platform 50 also includes apolishing pad 56, and it is to be fixedly installed on the polished land 58.

When carrying out CMP when polishing, rubbinghead 52 is to apply a downforce to givewafer 54, and polished ofwafer 54 contacted with polishing pad 56.Polishing pad 56 can be the polyurethanes (foamed polyurethane) of foaming or design the irrigation canals and ditches structure that different pattern is arranged that on the material membrane that polyurethanes constituted in addition, polishingpad 56 also may comprise other material.On polishingpad 56, then be distributed with deployed in advance polishing slurries (slurry), provide polishing required polishing agent (abrasive) and other active chemical components, rubbinghead 52 then is rotated itsrotating shaft 62 and 60 respectively simultaneously with polished land 58, and mode provides needed chemical force of polished wafer surface material layer and mechanical force by this.

See also Fig. 2, what it illustrated is the cross-sectional view of the rubbing head of the preferred embodiment of the present invention.As shown in Figure 2, rubbinghead 52 of the present invention includes ahousing 150 haply, a Waffer edge covers ring (retaining ring) 152, one discoid supporting back board (disk-shaped backingplate) 154 and one brilliant back of the body cushion pad (backing film) 156.

Housing 150 can be connected with a power transmission shaft (drive shaft), and rotates towards a fixed-direction with turningcylinder drive wafer 54countershafts 62 in the polishing stage.Turning cylinder basically the polishing stage approximately with polishingpad 56 invertical state.Housing 150 can be withwafer 56 big or small similar, rounded hood-like, in addition, have gas supply pipeline to passhousing 150, be used for vapour-pressure typecontrol rubbing head 52 to give the downforce of wafer 54.Utilize O type ring (O-ring) then can between gas supply pipeline, form airtight conditions.

Wafer 54 is to coverring 152 by Waffer edge to limit and be fixed in the rubbing head 52.Waffer edge coversring 152 and is generally the ring-type moulding, can be locked inhousing 150 lower position on every side by screw.Waffer edge coversring 152 and define a pocket zone (pocket area) underhousing 150, and its size is used for holdingwafer 54 just.In addition, Waffer edge covers a ring inner surface of 152 can interlockwafer 54, skids off from rubbinghead 52 bottoms during polishing to avoidwafer 54.

Brilliant back of thebody cushion pad 156 is plate-like moulding films, can be constituted by macromolecular material, and its position can be pasted on supportingback board 154 by pressure sensitive glue (pressure sensitiveadhesive) between supporting backboard 154 and wafer 54.Brilliant back of thebody cushion pad 156 is comparatively responsive for pressure, can cushion the downforce that puts onwafer 54 back sides, and can compensate the small out-of-flatness surface ofbackboard 154 or chip back surface.

In addition, rubbinghead 52 of the present invention also can comprise abarrier film 158, be generally an endless flexible material film (annular ring of a flexible material), the one end is to cover 152 on ring byhousing 150 and Waffer edge to clamp, and the other end then can utilize a strangulation ring (clamp ring) to lock above supportingback board 154 with screw.The composition ofbarrier film 158 can be rubber or artificial rubber (elastomeric-coatedfibric), for example NYLON^TMOr NOMEX^TM, perhaps glass fibre or the like.

Supporting backboard 154 can be by harder not easily broken made flat disc of material such as stainless steels, and its size can be bigger a little than wafer 54.When carrying out the CMP polishing, the downforce of rubbinghead 52 is the back side that puts onwafer 54 by supporting backboard 154, makes downforce and polishing power can be dispersed to wafer surface uniformly, reaches the purpose of uniform polish by this.Supporting backboard 154 has a wafer contact-making surface and an amorphous sheet contact-making surface, and when wherein carrying out the CMP polishing, the wafer contact-making surface of supportingback board 154 is against the back side of livingwafer 54.

According to a preferred embodiment of the invention, supporting backboard 154 has a plurality of pressure areas (pressure zone) that non-concentric circles (non-concentric) is arranged that are, and is defined out bymiddle opening 162 independently and theopening 164 that is centered around around the middle opening respectively.The a plurality of numbers that are the pressure area that non-concentric circles arranges that had on the supporting backboard 154 if greater than 5 then for preferable.

See also Fig. 3 and Fig. 4, wherein look schematic diagram on the supporting back board according to the preferred embodiment of theinvention 154 that Fig. 3 illustrates, Fig. 4 illustrates be another preferred embodiment according to the present invention supportingback board 154 on look schematic diagram.As shown in Figure 3, form the pressure area of 6 non-concentric circles altogether in supporting backboard 154, whereinmiddle opening 162 by around opening 164 surrounded.Middle opening 162 is a circular open, andopening 164 then is fan-shaped opening on every side.

As shown in Figure 4, according to another preferred embodiment of the invention, form the pressure area of 9 non-concentric circles altogether in supporting backboard 154, whereinmiddle opening 162 is surrounded by opening 164 on every side equally, andmiddle opening 162 is pros or rectangular aperture, andopening 164 then is irregular opening on every side.In addition, be formed on the opening design on the supporting backboard 154, its number can surpass more than 9, it will be understood by those skilled in the art that the patterns of openings in Fig. 3 and Fig. 4 and distribute only to be illustration.

As shown in Figure 2, according to a preferred embodiment of the invention, rubbinghead 52 of the present invention also can include a plurality of air bag devices (pneumatic bladder) 182 and 184, it is placed on the supporting backboard 154 correspondingmiddle opening 162 respectively and on every side in theopening 164, is used for controlling independently the downforce that is applied towafer 54 back sides in indivedual pressure areas.Above-mentioned a plurality ofair bag device 182 and 184 inflation and bleed and to finish by the individual gases supply line that is connected to gas source or pumping.

See also Fig. 5, what it illustrated is the rubbing head cross-sectional view of another preferred embodiment of the present invention.As shown in Figure 5, the rubbinghead 52 of another preferred embodiment of the present invention is with rubbing head difference shown in Figure 2, in each non-concentric circles pressure area, be respectively arranged with pressureresponsive element 192 and 194 in addition, wherein pressureresponsive element 192 is arranged in themiddle opening 162, and pressureresponsive element 194 is arranged on every side in theopening 164.

According to a preferred embodiment of the invention, pressureresponsive element 192 and 194 can be piezoelectric, piezoelectric crystalline, piezoelectric inductor or piezoelectric ceramics inductor etc., for example, and barium titanate (BaTiO₃), AlN, ZnO, lead zirconate titanate (PZT), zirconia, tantalum oxide (Ta₂O₅), tantalates, quartz, tourmaline, Luo De salt, niobates etc.

Another principal character of the present invention is that pressureresponsive element 192 and 194 can be detected wafer surface in the CMP polishing process because the pressure that height rises and falls to be produced changes, and signal can be sent back the control module of CMP board, computer for example, control module is immediately controlled the pressure of the above-mentioned a plurality ofair bag devices 182 of exporting to of pumping or gas source and 184 again according to the signal of pressureresponsive element 192 and 194 feedbacks, change the downforce in the non-concentric circles pressure area by this, so make the polishing of wafer to be controlled accurately, and improve the polishing uniformity, and can adapt to different wafer surface profiles and all can obtain preferable flatness.

The above only is the preferred embodiments of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.

Claims (14)

1. rubbing head that is applied to CMP process comprises:

One housing;

One Waffer edge covers ring, is locked in a lower position of this housing;

One supporting back board, it has a plurality of pressure areas that non-concentric circles is arranged that are, and this supporting back board has a wafer contact-making surface and an amorphous sheet contact-making surface, and when wherein carrying out a chemically mechanical polishing, this wafer contact-making surface of this supporting back board is against living a chip back surface; And

One pressure apparatus is used for when carrying out this chemically mechanical polishing, and independent control is these a plurality of being in the non-concentric circles line pressure district individually, are applied to the pressure of this chip back surface.

2. the rubbing head that is applied to CMP process as claimed in claim 1, wherein this rubbing head also comprises a brilliant back of the body cushion pad, is located between this chip back surface and this supporting back board.

3. the rubbing head that is applied to CMP process as claimed in claim 1, wherein this a plurality of to be pressure areas that non-concentric circles arranges be that a plurality of separate openings by this supporting back board is defined out, this a plurality of separate openings opening on every side of comprising a middle opening and centering on this middle opening wherein.

4. the rubbing head that is applied to CMP process as claimed in claim 1, wherein this rubbing head also comprises a barrier film.

5. the rubbing head that is applied to CMP process as claimed in claim 4, wherein this barrier film is an endless flexible material film.

6. the rubbing head that is applied to CMP process as claimed in claim 1, wherein this rubbing head also comprises a pressure responsive element, is located at respectively this a plurality of being in the pressure area that non-concentric circles arranges.

7. the rubbing head that is applied to CMP process as claimed in claim 6, wherein this pressure responsive element comprises piezoelectric, piezoelectric crystalline, piezoelectric inductor or piezoelectric ceramics inductor.

8. the rubbing head that is applied to CMP process as claimed in claim 6, wherein this pressure responsive element comprises barium titanate, AlN, ZnO, lead zirconate titanate, zirconia, tantalum oxide, tantalates, quartz, tourmaline, Luo De salt or niobates.

9. the rubbing head that is applied to CMP process as claimed in claim 6, wherein this pressure responsive element is detected the surface of this wafer because the pressure that is produced that just rises and falls changes in this chemically mechanical polishing, and a feedback signal can be sent back a control module.

10. cmp method comprises:

One wafer is fixed on the rubbing head, and wherein this rubbing head comprises a pressure apparatus, and it is controlled by a control module, be used for when carrying out a chemically mechanical polishing, control is applied on the back side of this wafer independently, and each is in the pressure area of non-concentric circles arrangement, individual other pressure;

This rubbing head and a polishing pad are rotated, and wherein this rubbing head is to be placed on this polishing pad;

Provide a downforce to this wafer; And

Material layer on this wafer is polished removal equably.

11. cmp method as claimed in claim 10, wherein this method also comprises provides at least one pressure responsive element, is located in respectively this pressure area that is non-concentric circles arrangement on this wafer.

12. cmp method as claimed in claim 11, wherein this pressure responsive element comprises piezoelectric, piezoelectric crystalline, piezoelectric inductor or piezoelectric ceramics inductor.

13. cmp method as claimed in claim 11, wherein this pressure responsive element comprises barium titanate, AlN, ZnO, lead zirconate titanate, zirconia, tantalum oxide, tantalates, quartz, tourmaline, Luo De salt or niobates.

14. cmp method as claimed in claim 11, wherein this pressure responsive element is detected the surface of this wafer because the pressure that is produced that just rises and falls changes in this chemically mechanical polishing, and a feedback signal can be sent back a control module.

Images