CN102909646B - Chemical mechanical grinding method - Google Patents

Chemical mechanical grinding method Download PDF

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Publication number
CN102909646B
CN102909646B CN201110218623.2A CN201110218623A CN102909646B CN 102909646 B CN102909646 B CN 102909646B CN 201110218623 A CN201110218623 A CN 201110218623A CN 102909646 B CN102909646 B CN 102909646B
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grinding
layer
described
ground
wafer
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CN201110218623.2A
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Chinese (zh)
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CN102909646A (en
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邵群
王庆玲
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中芯国际集成电路制造(上海)有限公司
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Abstract

The invention provides a chemical mechanical grinding method. The chemical mechanical grinding method comprises the following steps of grinding and removing a first to-be-ground layer on a wafer by utilizing a fixed particle grinding pad; selecting the wafer with grinding residue; covering a second to-be-ground layer, wherein the material of the second to-be-ground layer is the same as that of the first to-be-ground layer; and grinding and removing the second to-be-ground layer on the wafer. According to the chemical mechanical grinding method provided by the invention, the second to-be-ground layer is covered on the wafer with the grinding residue, the second to-be-ground layer is ground by utilizing the fixed particle grinding pad, the material of the second to-be-ground layer is the same as that of the first to-be-ground layer, and thus the first to-be-ground layer is ground through the same grinding method; and during the process of grinding the second to-be-ground layer, the grinding rate of the fixed particle grinding pad is gradually increased and is up to a stable value, the grinding residue is completely removed by utilizing the grinding rate while the second to-be-ground layer is removed, thus the grinding effect is increased, and the grinding residue is completely removed.

Description

Chemical and mechanical grinding method

Technical field

The present invention relates to a kind of method for manufacturing integrated circuit, particularly relating to a kind of chemical and mechanical grinding method for improving immobilized particles grinding pad grinding effect.

Background technology

Electronic system and the progress of circuit to modern society have significant contribution, and for multiple application to obtain best result.The electronic system of this optimum can be provided to generally include integrated circuit (IC) in chip die.For the manufacture of IC wafer, performing polishing step in effective and sufficient mode is a key.Complicated IC has multiple different superimposed layer usually, every one deck counterpoise be stacked in front one deck above and include multiple assembly by multiple mutual contact mode.When being superposed in said layer by IC assembly, the final surface topography of IC of these complexity is scraggly (such as, they are similar to the convex-concave land " mountain range " in multiple riser portions or " hills " or falling portion or " mountain valley " usually).

In prior art, polishing is the best approach obtaining crystal column surface complanation.The most frequently used polishing technology is cmp (CMP, Chemical Mechanical Planarization, also chemically mechanical polishing is claimed), described CMP uses the lapping liquid of spraying on polishing pad, to contribute to making wafer smoothing and with predictable mode complanation.The complanation attribute of lapping liquid is generally made up of abrasion friction component and chemical reaction component.Abrasion friction component comes from the abrasive grains be suspended in lapping liquid.Described abrasive grains can increase the abrasive characteristic of polishing pad when making CONTACT WITH FRICTION with crystal column surface.The material generation chemical reaction of chemical reaction component and described crystal column surface, by with will the in addition crystal column surface generation chemical reaction of polishing and softening or decompose.Abrasion friction component and chemical reaction component contribute to grinding pad planarizing surface of wafer.

Mode lapping liquid being distributed to polishing pad can affect the grinding of lapping liquid when helping polishing and the effect of chemical characteristic significantly, affects clearance simultaneously.Traditional lapping liquid is sent to crystal column surface.The irregular surface of the usual tool of polishing material, comprises and is multiplely formed in very little pit in pad interface and groove.Pit on described convex-concave surface and groove are used as reservoir, can collect lapping liquid, to be sent to just polished crystal column surface.Although the lapping liquid usually used in chemical mechanical planarization process can provide some benefit, also disadvantageous side effect can be caused.

Traditional lapping liquid compartment system does not generally provide lapping liquid being uniformly distributed on a surface of a wafer; such as new lapping liquid is supplied to the edge of wafer by most of lapping liquid compartment system; then be transported to the center of wafer through the rotation of grinding pad and wafer, the solid abrasive particle in part lapping liquid can precipitate or assemble in lapping liquid solution.When then lapping liquid is transported to crystal circle center, the abrasive characteristic of lapping liquid can weaken.If a part for wafer exposes and excessive lapping liquid joint, then this part can be got rid of at faster speed.Thus, lapping liquid can make more abrasion friction masterpiece for the edge of wafer, thus can get rid of material quickly, and the slurry being positioned at crystal circle center's partial failure then more slowly can remove material, causes the crystal column surface forming uneven polishing.In addition, in polishing process, along with the consumption of lapping liquid can produce useless particle, these useless particles comprise the material that the grinding particle of inefficacy and wafer are removed.The grinding particle lost efficacy is not easy to decompose because of chemical reaction, then can be deposited on crystal column surface with the formation of useless particle, enter in groove in polishing pad and pit, affect grinding effect and efficiency.

Therefore, industry proposes a kind of effective removal crystal column surface and the chemical-mechanical grinding device preventing groove and pit phenomenon from occurring, and namely adopts immobilized particles grinding pad (Fixed Abrasive Pad).The set of described immobilized particles grinding pad fixing abrasive grains and grinding pad, do not need the fixing abrasive grains of free floating, can reach preferably grinding effect, and this is more and more important to the technology that 45nm level is even following.The patent No. be US2002/0049027A1 U.S. patents disclose a kind of immobilized particles grinding pad on chemical-mechanical grinding device, described in this patent, immobilized particles grinding pad solves above-mentioned technical problem.In addition, publication number is fixing abrasive chemical-mechanical grinding device and its implementation that the Chinese patent of CN1438931A discloses a kind of swing, chemical-mechanical grinding device described in this patent comprises grinding pad, feeding roller and the withdrawal cylinder with fixing abrasive grains, and utilize the configuration of reel operation to control the motion of described grinding pad, thus in extremely short time and few labour, used for grinding pad part is replaced by new grinding pad, continue to carry out cmp to wafer.

Newer technique owing to utilizing the grinding technics of immobilized particles grinding pad, technology controlling and process is not very ripe, the problems such as the pressure inequality in process of lapping or hardware failure all can cause crystal column surface grinding rate uneven, cause the wearing and tearing of fixing abrasive grains or come off, reduce grinding rate, the grinding even causing crystal column surface to be left over is residual causes scuffing (Scratch) to wafer, affects grinding effect, affects productive rate and the reliability of wafer.

Therefore, in process of lapping, chemical liquids can be flowed between immobilized particles grinding pad and wafer layer to be ground, containing polymeric additive in this chemical liquids, to reduce the scuffing of fixing abrasive grains to wafer.Simultaneously, polymeric additive is also easy to be adsorbed in polish stop layer, and when immobilized particles grinding pad is ground to polish stop layer, a large amount of polymeric additives will be adsorbed onto this polish stop layer surface, stop the further grinding to crystal column surface, thus reach self-braking function.Fig. 1 is the chemical and mechanical grinding method utilizing immobilized particles grinding pad in prior art.As shown in Figure 1, the substrate 10 of wafer comprises polish stop layer 14 and layer to be ground (not indicating in figure).In process of lapping, fixing abrasive grains 21 and the layer to be ground of immobilized particles grinding pad 20 produce mechanical friction, remove layer to be ground, simultaneously, chemical liquids 30 is flowed into, containing polymeric additive 31 in this chemical liquids 30 between the layer to be ground and fixing abrasive grains 21 of wafer; When cmp proceeds to end stage, crystal column surface can expose most polish stop layer 14, then polymeric additive 31 can be adsorbed on polish stop layer 14 surface, the grinding of the immobilized particles that slows down grinding pad 20 pairs of etching stop layers, thus the scuffing reducing fixing abrasive grains 21 pairs of wafers.

But, because a large amount of polymeric additives 31 is adsorbed on the surface of polish stop layer 14, less grinding residual 12 can wrap up by polymeric additive 31, this part grinding residual 12 cannot be efficiently removed, thus reduce grinding effect.

Summary of the invention

The object of the present invention is to provide a kind of chemical and mechanical grinding method, to improve the grinding effect of immobilized particles grinding pad.

For solving the problem, the invention provides a kind of chemical and mechanical grinding method, to improve the grinding effect of immobilized particles grinding pad, comprising: utilize immobilized particles grinding pad to grind the first layer to be ground removed on wafer; Detect the grinding effect of described wafer, select and there is the residual wafer of grinding; Have covering the second layer to be ground on the residual wafer of grinding described, the material of described second layer to be ground is identical with the material of the first layer to be ground; Described immobilized particles grinding pad grinding described second layer to be ground of removal and described grinding is utilized to remain.

Further, in the step that the second layer to be ground utilized on described immobilized particles grinding pad grinding removal wafer and described grinding remain, the grinding rate of described immobilized particles grinding pad improves gradually, finally reaches a stationary value.

Preferably, in the step that the second layer to be ground utilized on described immobilized particles grinding pad grinding removal wafer and described grinding remain, the grinding rate of described immobilized particles grinding pad finally reaches a stationary value, and described stationary value is 300 ~ 1500 A/min of clocks.

Further, the thickness of described second layer to be ground is less than the thickness of described first layer to be ground.

Further, thickness 50 ~ 1000 dust of described second layer to be ground.

Further, described first layer to be ground is shallow trench isolating oxide layer, layers of copper, tungsten layer, Ge-Sb-Te layer or metal gates dielectric layer.

Further, utilizing described immobilized particles grinding pad to grind in the step of the first layer to be ground removed on wafer, also comprising and flowing into chemical liquids between described fixing abrasive grains and described first layer to be ground.

Further, in the step utilizing described immobilized particles grinding pad grinding described second layer to be ground of removal and described grinding to remain, also comprise and flow into chemical liquids between described fixing abrasive grains and described second layer to be ground.

Further, polymeric additive is contained in described chemical liquids.

In sum, chemical and mechanical grinding method of the present invention, after described first layer to be ground is removed in grinding, select and there is the residual wafer of grinding, there is covering the second layer to be ground on the residual wafer of grinding, and utilize immobilized particles grinding pad to grind the second layer to be ground, grind in the process of the second layer to be ground utilizing immobilized particles grinding pad, grinding rate improves gradually and reaches a stationary value, while removal second layer to be ground, utilize the effect of inertia of stable grinding rate thoroughly to remove the second layer to be ground and grind residual.

Further, because the material of the second layer to be ground is identical with first to be ground layer of material, therefore identical lapping mode can be adopted to grind.The thickness of the second layer to be ground selects 50 ~ 1000 dusts, ensure that grinding rate has time enough to bring up to stationary value on the one hand, utilize the effect of inertia of stable grinding rate thoroughly to remove the second layer to be ground and grind residual, the thickness of the second layer to be ground is moderate on the other hand ensure that shorter milling time, and then while raising immobilized particles grinding pad grinding effect, improve the grinding efficiency of immobilized particles grinding pad.

Accompanying drawing explanation

Fig. 1 is the chemical and mechanical grinding method utilizing immobilized particles grinding pad in prior art.

Fig. 2 is the schematic flow sheet of chemical and mechanical grinding method in one embodiment of the invention.

Fig. 3 is the brief configuration schematic diagram of wafer before cmp in one embodiment of the invention.

Fig. 4 ~ Fig. 7 is the brief configuration schematic diagram in one embodiment of the invention in chemical and mechanical grinding method process of lapping.

Detailed description of the invention

For making content of the present invention clearly understandable, below in conjunction with Figure of description, content of the present invention is described further.Certain the present invention is not limited to this specific embodiment, and the general replacement known by those skilled in the art is also encompassed in protection scope of the present invention.

Secondly, the present invention's detailed statement that utilized schematic diagram to carry out, when describing example of the present invention in detail, for convenience of explanation, schematic diagram, should in this, as limitation of the invention not according to general ratio partial enlargement.

The to be ground layer of chemical and mechanical grinding method of the present invention on grinding crystal wafer, Fig. 3 is the brief configuration schematic diagram of wafer before cmp in one embodiment of the invention, as shown in Figure 3, the substrate 100 of described wafer to be ground is formed with successively polish stop layer 104 and the first layer 101 to be ground, utilize immobilized particles grinding pad to grind and remove described first layer 101 to be ground, and stop at described polish stop layer 104.Chemical and mechanical grinding method of the present invention can be used for fleet plough groove isolation structure, copper interconnection layer, tungsten contact hole layer, Ge-Sb-Te layer and the isostructural grinding technics of HiK dielectric layer, therefore described first layer 101 to be ground can be shallow trench isolation from oxide layer, layers of copper, tungsten layer, Ge-Sb-Te layer or metal gates dielectric layer etc., the present invention will not limit this.

Fig. 2 is the schematic flow sheet of chemical and mechanical grinding method in one embodiment of the invention, and Fig. 4 ~ Fig. 7 is the brief configuration schematic diagram in one embodiment of the invention in chemical and mechanical grinding method process of lapping.Incorporated by reference to Fig. 2 ~ Fig. 7, the chemical and mechanical grinding method that one embodiment of the invention provides, comprises the following steps:

Step S01: utilize immobilized particles grinding pad 200 to grind the first layer 101 to be ground removed on wafer, specifically as shown in Figure 4;

Particularly, carry out cmp step, utilize the first layer 101 to be ground on the substrate 100 of immobilized particles grinding pad 200 grinding removal wafer, and stop in polish stop layer 104; In process of lapping, chemical liquids 300 is added between the fixing abrasive grains 201 and the first layer 101 to be ground of immobilized particles grinding pad 200, containing polymeric additive 301 in described chemical liquids 300, polymeric additive 301 plays lubrication between fixing abrasive grains 201 and the first layer 101 to be ground, the scuffing that the fixing abrasive grains 201 pairs of crystal column surfaces being conducive to reducing cause.Simultaneously; polymeric additive 301 also can be easy to be adsorbed in polish stop layer 104; when being ground to polish stop layer 104; a large amount of polymeric additives 301 will be adsorbed onto described etching stop layer 104 surface; stop grinding further, thus the not polished damage of the structure of protection etching stop layer 104 and etching stop layer less than 104.

Step S02: the grinding effect detecting described wafer, selects the wafer with grinding residual 102.

After step S01, and the first layer 101 to be ground on the wafer of not all thoroughly can be ground removal, and as shown in Figure 5, part wafer has the grinding residual 102 of the first layer 101 to be ground at its substrate 100 surface residual.Polymeric additive 301 can remain residual impurity 102 surface by wrapping portion, immobilized particles grinding pad 200 cannot be ground and remove remaining residue impurity 102, thus forms grinding residual 102 as shown in Figure 5.The grinding whether had as shown in Figure 5 by the crystal column surface after defect detector (Defect Scan) or microscopic examination grinding remains 102, if having grinding residual 102, wafer will carry out subsequent step.

Step S03: cover the second layer 103 to be ground at the crystal column surface with grinding residual 102, the material of described second layer 103 to be ground is identical with the material of the first layer 101 to be ground, specifically as shown in Figure 6;

Wherein, the thickness of described second layer 103 to be ground is less than the thickness of the first layer 101 to be ground, and the thickness of described second layer 103 to be ground is preferably 50 ~ 1000 dusts.In the present embodiment, the material of described second layer 103 to be ground is identical with the material of the first layer 101 to be ground, therefore identical grinding technics can be adopted to grind, and reduces grinding cost; And the thickness of the second layer 103 to be ground is 50 ~ 1000 dusts, thinner thickness, milling time is short, less on the grinding efficiency impact of fixing abrasive grains pad 200.

Step S04: utilize described immobilized particles grinding pad 200 to grind the second layer 103 to be ground and the described grinding residual 102 of removal crystal column surface, and stop in polish stop layer 104, form structure shown in Fig. 7.

Preferably, grind at described immobilized particles grinding pad 200 in the process of the second layer 103 to be ground, grinding rate improves gradually and reaches a stationary value.While eliminating the second layer 103 to be ground, the effect of inertia of grinding rate is utilized thoroughly to remove grinding residual 102 and second layer 103 to be ground of the first layer 101 to be ground.Wherein, described stationary value (stable grinding rate) is 300 ~ 1500 A/min of clocks.

In sum, chemical and mechanical grinding method of the present invention, after described first layer 101 to be ground is removed in grinding, select the wafer with grinding residual 102, the second layer 103 to be ground is covered at the wafer upper surface with grinding residual 102, and utilize immobilized particles grinding pad 200 to grind the second layer 103 to be ground, grind in the process of the second layer to be ground utilizing immobilized particles grinding pad 200, grinding rate improves gradually and reaches a stationary value, while removal second layer to be ground, the effect of inertia of stable grinding rate is utilized thoroughly to remove the second layer 103 to be ground and grinding residual 102.

Further, because the material of the second layer 103 to be ground is identical with the first layer 101 material to be ground, therefore can grind with identical lapping mode.The thickness of the second layer 103 to be ground selects 50 ~ 1000 dusts, ensure that grinding rate has time enough to bring up to stationary value on the one hand, the second layer 103 to be ground and grinding residual 102 is thoroughly removed to utilize the effect of inertia of stable grinding rate, the thickness of the second layer 103 to be ground is moderate on the other hand ensure that shorter milling time, and then while raising immobilized particles grinding pad 200 grinding effect, improve the grinding efficiency of immobilized particles grinding pad 200.

Although the present invention discloses as above with preferred embodiment; so itself and be not used to limit the present invention; have in any art and usually know the knowledgeable; without departing from the spirit and scope of the present invention; when doing a little change and retouching, therefore protection scope of the present invention is when being as the criterion depending on those as defined in claim.

Claims (7)

1. a chemical and mechanical grinding method, for improving the grinding effect of immobilized particles grinding pad, comprising:
Immobilized particles grinding pad is utilized to grind the first layer to be ground removed on wafer;
Detect the grinding effect of described wafer, select and there is the residual wafer of grinding;
Have covering the second layer to be ground on the residual wafer of grinding described, the material of described second layer to be ground is identical with the material of described first layer to be ground;
Described immobilized particles grinding pad grinding described second layer to be ground of removal and described grinding is utilized to remain;
It is characterized in that, utilizing described immobilized particles grinding pad to grind in the step of the first layer to be ground removed on wafer, to the chemical liquids flowed between described immobilized particles grinding pad and described first layer to be ground containing polymeric additive; In the step that the second layer to be ground utilized on described immobilized particles grinding pad grinding removal wafer and described grinding remain, the grinding rate of described immobilized particles grinding pad improves gradually, finally reaches a stationary value.
2. chemical and mechanical grinding method as claimed in claim 1, it is characterized in that, described stationary value is 300 ~ 1500 A/min of clocks.
3. chemical and mechanical grinding method as claimed in claim 1, it is characterized in that, the thickness of described second layer to be ground is less than the thickness of described first layer to be ground.
4. chemical and mechanical grinding method as claimed in claim 3, is characterized in that, thickness 50 ~ 1000 dust of described second layer to be ground.
5. chemical and mechanical grinding method as claimed in claim 1, it is characterized in that, described first layer to be ground is shallow trench isolating oxide layer, layers of copper, tungsten layer, Ge-Sb-Te layer or metal gates dielectric layer.
6. chemical and mechanical grinding method as claimed in claim 1, it is characterized in that, in the step utilizing described immobilized particles grinding pad grinding described second layer to be ground of removal and described grinding to remain, also comprise and flow into chemical liquids between described immobilized particles grinding pad and described second layer to be ground.
7. chemical and mechanical grinding method as claimed in claim 6, is characterized in that, containing polymeric additive in described chemical liquids.
CN201110218623.2A 2011-08-01 2011-08-01 Chemical mechanical grinding method CN102909646B (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6135856A (en) * 1996-01-19 2000-10-24 Micron Technology, Inc. Apparatus and method for semiconductor planarization
CN101783292A (en) * 2009-01-20 2010-07-21 中芯国际集成电路制造(上海)有限公司 Method for reworking metal layer
CN101982303A (en) * 2010-10-11 2011-03-02 南京航空航天大学 Grooved frozen solidified grinding material polishing pad and preparation method thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5919082A (en) * 1997-08-22 1999-07-06 Micron Technology, Inc. Fixed abrasive polishing pad
US6520833B1 (en) * 2000-06-30 2003-02-18 Lam Research Corporation Oscillating fixed abrasive CMP system and methods for implementing the same
US6964880B2 (en) * 2003-06-27 2005-11-15 Intel Corporation Methods for the control of flatness and electron mobility of diamond coated silicon and structures formed thereby
US7064069B2 (en) * 2003-10-21 2006-06-20 Micron Technology, Inc. Substrate thinning including planarization
JP4237152B2 (en) * 2005-03-04 2009-03-11 エルピーダメモリ株式会社 Manufacturing method of semiconductor device
DE102009030292B4 (en) * 2009-06-24 2011-12-01 Siltronic Ag Method for polishing both sides of a semiconductor wafer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6135856A (en) * 1996-01-19 2000-10-24 Micron Technology, Inc. Apparatus and method for semiconductor planarization
CN101783292A (en) * 2009-01-20 2010-07-21 中芯国际集成电路制造(上海)有限公司 Method for reworking metal layer
CN101982303A (en) * 2010-10-11 2011-03-02 南京航空航天大学 Grooved frozen solidified grinding material polishing pad and preparation method thereof

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