CN102009385A - Chemical mechanical polishing method for semiconductor wafer - Google Patents
Chemical mechanical polishing method for semiconductor wafer Download PDFInfo
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- CN102009385A CN102009385A CN 201010531953 CN201010531953A CN102009385A CN 102009385 A CN102009385 A CN 102009385A CN 201010531953 CN201010531953 CN 201010531953 CN 201010531953 A CN201010531953 A CN 201010531953A CN 102009385 A CN102009385 A CN 102009385A
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Abstract
The invention provides a chemical mechanical polishing method for a semiconductor wafer. In the method, chemical mechanical polishing is performed on the wafer by using polishing solution and a polishing pad in chemical mechanical equipment, wherein the polishing pad has the hardness of 40 to 55 degrees, the compressibility of 10 to 25 percent and the compression elasticity of 83 to 94 percent; the polishing solution is solution with the concentration of 2.5 to 4.5 weight percent based on the total weight of the polishing solution; and based on the total weight of the polishing solution, besides water, the polishing solution comprises the following components in part by weight: 10 to 25 parts of sodium salt of dichloroisocyanuric acid, 15 to 30 parts of tripolyphosphate, 2 to 8 parts of bicarbonate and 15 to 30 parts of anhydrous sulphate.
Description
Technical field
The present invention relates to a kind of cmp method of semiconductor wafer.
Background technology
At present, polishing technology is widely used in the manufacturing of various semi-conducting materials, particularly semiconductor wafer.Particularly, cmp method (CMP) has been widely used to satisfy the technical indicator of high requests such as surface roughness, surface planarity better as a kind of polishing technology that can generate the high degree of planarity surface.
In CMP, polishing fluid is a key factor that influences properties of product.The polishing fluid that uses mainly is divided into acid polishing slurry and alkalescence polishing liquid at present.The reaction speed of acid polishing slurry and semi-conducting material is slower, so use acid polishing slurry processing can access more stable surface before polishing finishes.In order to obtain the wafer that surface property is enough to meet the demands, in the prior art, what mainly adopt is to use the alkalescence polishing liquid rough polishing earlier by Twp-sided polishing machine, and then uses the method for acid polishing slurry fine polishing.But, use the shortcoming of acid polishing slurry maximum to be, wherein have a large amount of metal ions, thereby in wafer manufacturing process, can bring metallic pollution, particularly Cu ionic soil inevitably, make the chip surface after polishing metal ion residual more.As everyone knows, how many meetings of the metal ion that chip surface after polishing is entrained directly influence the serviceability of device, for example, the wafer surface metal ion is residual too much can to cause wafer epitaxial loayer and substrate interface electric conductivity after making device strong excessively, thereby reduces the serviceability of device.Particularly, in semi-insulated GaAs (GaAs) material polishing process, the wafer surface metal ion too much can cause the leakage current of integrated circuit to increase, thereby breakdown device causes device to scrap.In addition, in present employed acid polishing slurry, good and the selectivity of polishing performance is preferably the silica acid polishing slurry, yet, this polishing fluid also has problems in storage and use: the Ludox of silica acid polishing slurry is reunited easily, thereby make the particle diameter of silica dioxide granule increase several times, unsuitable long term storage; In addition, this polishing fluid is very easily crystallization in use, thereby makes the wafer surface in the polishing process produce the machinery scuffing; And the particle size of Ludox is also influential to the thickness degree of wafer polishing rear surface.
In addition, existing alkalescence polishing liquid also has problems, the fast and lack of homogeneity of itself and wafer, particularly gallium arsenide wafer reaction speed, and chip surface after polishing is easy to generate uneven defective.
Summary of the invention
The invention provides a kind of cmp method of semiconductor wafer, be included in the chemical-mechanical polisher, use a kind of polishing fluid and a polishing pad that wafer is implemented chemically mechanical polishing, the hardness of described polishing pad is 40-55 ° of (Shore hardness, down together), compression ratio is 10-25%, elasticity of compression rate is 83%-94%, described polishing fluid is that a kind of concentration is that (with the polishing fluid gross weight is benchmark to 2.5-4.5 weight %, solution down together), the weight portion of composition consists of outside dewatering in the polishing fluid: dichlorisocyanurate 10-25, tripolyphosphate 15-30, bicarbonate 2-8 and anhydrous sulfate 15-30.
Adopt finishing method of the present invention, can significantly reduce the metal ion content of wafer surface, can also obtain to be enough to simultaneously gratifying stable, uniform wafer surface.
Description of drawings
Fig. 1 is an example of equipment that is used for the cmp method of semiconductor wafer of the present invention.
The specific embodiment
The cmp method of semiconductor wafer of the present invention is included in the chemical-mechanical polisher, use a kind of polishing fluid and a polishing pad that wafer is implemented chemically mechanical polishing, the hardness of described polishing pad is 40-55 °, compression ratio is 10-25%, elasticity of compression rate is 83%-94%, described polishing fluid is that a kind of concentration is that (with the polishing fluid gross weight is benchmark to 2.5-4.5 weight %, the aqueous solution down together), the weight portion of composition consists of outside dewatering in the polishing fluid: dichlorisocyanurate 10-25, tripolyphosphate 15-30, bicarbonate 2-8 and anhydrous sulfate 15-30.
In the methods of the invention, described polishing fluid concentration is 2.5-4.5 weight %, is preferably 3.0-4.0%, more preferably 2.6-3.8%.Preferably, the pH of described polishing fluid is 6.0-9.0, is preferably 7.5-9.0, more preferably 8.0-9.0.
The present invention is used for the polishing fluid of wafer chemically mechanical polishing, and beyond dewatering, it is dichlorisocyanurate 10-25 that its weight portion is formed, tripolyphosphate 15-30, bicarbonate 2-8 and anhydrous sulfate 15-30.In a preferred embodiment of the invention, outside polishing fluid dewatered, it was dichlorisocyanurate 15-20 that its weight portion is formed, tripolyphosphate 18-25, bicarbonate 3-5 and anhydrous sulfate 18-25.
In polishing fluid of the present invention, dichlorisocyanurate, tripolyphosphate, bicarbonate and anhydrous sulfate can adopt one of their water soluble salts separately.Preferably, dichlorisocyanurate, tripolyphosphate, bicarbonate and anhydrous sulfate are one of water miscible alkali metal salt separately or are ammonium salt, be preferably separately sodium salt or ammonium salt especially.
When preparing polishing fluid of the present invention, each component directly can be put into deionized water, dissolve, mix; Also can earlier each component be mixed, put into deionized water then, dissolve, mix; Also can respectively each component successively be put into deionized water, dissolve, mix.
Detect and find, polishing fluid of the present invention is compared with the chloride polishing fluid of prior art preparing airtight the depositing under the situation in back, can reduce the aerial concentration of chlorine, alleviates the influence for environment.
Further detect and find, polishing fluid of the present invention after preparation, can deposit reach 24 hours after again with and do not influence result of use.Therefore, polishing fluid of the present invention needn't be now with the current, thereby can reduce the number of operations of solution preparation.
Polishing fluid of the present invention can be realized the excellent polishing of wafer with the cooperation of its chemical substance (being dichlorisocyanurate, tripolyphosphate, bicarbonate and anhydrous sulfate) when low concentration.For example, be benchmark with the polishing fluid gross weight, the total percentage by weight of chemical substance is not higher than 4.5% in the polishing fluid.Like this, can reduce the chemical substance consumption, and reduce separating out of crystal in the solution, and then reduce the defective proportion of damaging (Damage) and cut (Scratch) in the wafer product, improve yield rate.
Polishing pad of the present invention is that a kind of hardness is 40-55 °, and compression ratio is 10-25%, and elasticity of compression rate is the polishing pad of 83%-94%, is made by nonwoven (being non-weaving cloth).As long as can reach described index request, any pad that is used for wafer polishing all can use.
In an embodiment preferred of the inventive method, the hardness of described polishing pad is preferably 42-53 °, more preferably 45-50 °.The compression ratio of described polishing pad is preferably 10-20%, more preferably 10-15%.The elasticity of compression rate of described polishing pad is preferably 85-90%.
The size of polishing pad with wait to grind the big or small identical of wafer, maybe can be slightly larger than the size of waiting to grind wafer.Perhaps, polishing pad is identical with the plane sizes of polishing machine bearing wafer, and wafer is by suitable isolated part or align member and spaced-apart.
In an embodiment preferred of the inventive method, described wafer is an IIIA-VA compounds of group wafer, preferred GaAs wafer.
Cmp method of the present invention can carry out in two-sided chemical-mechanical polisher or single face chemical-mechanical polisher.In an embodiment preferred of the inventive method, described chemical-mechanical polisher is a single side polishing machine; In this case, the polished one side of wafer contacts with polishing pad.
Unexpectedly, finishing method of the present invention not only can significantly reduce the metal ion content of wafer surface, Cu ion concentration particularly, thereby electric conductivity is strong excessively after avoiding wafer to make device, influence the serviceability of device, and can also obtain stability and the strong wafer surface of uniformity, thereby reach the technical indicator of high requests such as surface roughness, surface planarity better.TXRF (reflection x-ray fluorescence analyzer) tests discovery, adopts polishing fluid of the present invention, and chip surface after polishing Cu content is lower than 2.0 * 10
11Atom/cm
2, and the polishing fluid of employing prior art, chip surface after polishing Cu too high levels is a problem that is difficult to solve.
In addition, the present invention has avoided using acid higher polishing fluid, thereby has avoided acid polishing slurry, particularly silica acid polishing slurry to be difficult for problems such as storage and easy crystallization.In addition, method of the present invention need not to re-use acid polishing slurry and polishes after using polishing fluid to polish, can save operating cost, enhances productivity.
With Fig. 1 is example, and finishing method of the present invention is implemented in the following manner: polished wafer 3 is placed single-sided polishing equipment.Polissoir comprises two parts up and down: the surface lining of polishing lower wall 1 and rubbing head 4,1 is with polishing pad 2.Wafer 3 places between rubbing head 4 and the polishing pad 2.Two parts 1,4 respectively drive rotation with driving shaft R1 and R2 up and down.Lower wall 1 and rubbing head 4 adopt spinning solution in the same way, lower wall 1 rotating speed 20-50r/min, more preferably 25-40r/min, further preferred 30r/min.Rubbing head 4 rotating speed 20-50r/min, more preferably 25-40r/min, further preferred 30r/min.Polishing fluid is instilled on the polishing pad 2 by medicine liquid droplet hole 6 through liquor piping 5 and uses for polishing process, wherein, and the sealing of the horizontal pipe part end of liquor piping 5, and the downside of horizontal pipe part is evenly distributed with several medicine liquid droplet holes 6.Polished 3-30 minute, preferred after 5-15 minute, take out wafer, clean (in case of necessity, with water flushing again after the aqueous solution flushing of one of the following material of being selected from of 4-10 weight %: thiosulfate, sulphite, bisulfites, disulfate, iodate, bromate and chloritic one or more mixture, their sodium salt particularly, sylvite and ammonium salt), drying.
Preferably, the temperature with described polishing fluid is controlled to be 15-35 ℃, more preferably 18-30 ℃.Preferably, the flow velocity of described polishing fluid is 0.57-3.11ml/cm
2Wafer/min, more preferably 0.7-1.5ml/cm
2Wafer/min.
Unexpectedly, find to use single side polishing machine can effectively reduce the mechanical damage of wafer surface in the method for the invention.
In an embodiment preferred of the inventive method, also further comprise the wafer compressive load per unit area in the polishing process is controlled at 0.09-0.20kg/cm
2, more preferably 0.10-0.16kg/cm
2
Below with the present invention of non-limiting example exemplary illustration.
Embodiment
Prepare the various components of polishing fluid (calculating) according to the weight portion ratio in the table 1, prepare polishing fluid of the present invention (concentration is calculated with total solution weight) with deionized water by chemical substance weight.
The polishing fluid for preparing is used for polissoir SPM-19A single side polishing machine shown in Figure 1 (the only company more of Japan produces), and conditions such as polishing medicinal liquid flow are according to the rules implemented chemically mechanical polishing to the GaAs wafer of diameter 150.0mm, thickness 700 μ m.By placement wafer shown in Figure 1, once place 4 wafer, be placed on average, symmetrically on the plane of polishing machine bearing wafer, nonwoven polishing pad of the corresponding placement of each wafer, the polished one side of wafer contacts with polishing pad.Lower wall and rubbing head adopt spinning solution in the same way, polishing time 5 minutes.
Take out the most close experimenter's a wafer then from polishing machine, immediately with after the washed with de-ionized water, drying detects.
Test item:
1, with TXRF (reflection x-ray fluorescence analyzer; The TREX610 type, OSAKAJanpan Technos company) the testing wafer surface-element, wafer surface Cu ion is not higher than 2.0 * 10
11Atom/cm
2Be qualified (with " √ " expression).
2, with AFM (AFM) test chip surface after polishing roughness Ra, not to be higher than 1 dust be qualified (with " √ " expression) to reach.
3, flatness: the test and appraisal data are with TTV (general thickness variations)＜7 μ m, WARP (angularity)＜10 μ m, and that BOW (flexibility)＜5 μ m represents is qualified (representing with " √ ").
4, the amount of using up (being the thickness difference before and after the wafer polishing) is divided by the polishing time amount of calculating speed.
The results are summarized in table 1.
The composition of table 1 polishing fluid and experiment effect
Claims (10)
1. the cmp method of a semiconductor wafer, be included in the chemical-mechanical polisher, use a kind of polishing fluid and a polishing pad that wafer is implemented chemically mechanical polishing, the hardness of described polishing pad is 40-55 °, compression ratio is 10-25%, elasticity of compression rate is 83%-94%, described polishing fluid is that a kind of concentration is the aqueous solution of 2.5-4.5 weight %, the weight portion of composition consists of outside dewatering in the polishing fluid: dichlorisocyanurate 10-25, tripolyphosphate 15-30, bicarbonate 2-8 and anhydrous sulfate 15-30.
2. according to the cmp method of the semiconductor wafer of claim 1, wherein said polishing fluid concentration is 3.0-4.0 weight %.
3. according to the cmp method of the semiconductor wafer of claim 1 or 2, the pH of wherein said polishing fluid is 6.0-9.0.
4. according to the cmp method of the semiconductor wafer of claim 1 or 2, wherein said polishing fluid, beyond dewatering, it is dichlorisocyanurate 15-20 that its weight portion is formed, tripolyphosphate 18-25, bicarbonate 3-5 and anhydrous sulfate 18-25.
5. according to the cmp method of the semiconductor wafer of claim 1 or 2, wherein, dichlorisocyanurate, tripolyphosphate, bicarbonate and anhydrous sulfate are one of their water soluble salts separately.
6. according to the cmp method of the semiconductor wafer of claim 5, wherein dichlorisocyanurate, tripolyphosphate, bicarbonate and anhydrous sulfate are separately sodium salt or ammonium salt.
7. according to the cmp method of the semiconductor wafer of claim 1 or 2, the hardness of wherein said polishing pad is 42-53 °, and compression ratio is 10-20%, and elasticity of compression rate is 85-90%.
8. according to the cmp method of the semiconductor wafer of claim 1 or 2, wherein said wafer is an IIIA-VA compounds of group wafer.
9. the cmp method of semiconductor wafer according to Claim 8, wherein said wafer is the GaAs wafer.
10. according to the cmp method of the semiconductor wafer of claim 1 or 2, wherein said finishing method is implemented in single side polishing machine.
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| CN201010531953A CN102009385B (en) | 2010-11-02 | 2010-11-02 | Chemical mechanical polishing method for semiconductor wafer |
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|---|---|---|---|
| CN201010531953A CN102009385B (en) | 2010-11-02 | 2010-11-02 | Chemical mechanical polishing method for semiconductor wafer |
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| CN102009385A true CN102009385A (en) | 2011-04-13 |
| CN102009385B CN102009385B (en) | 2012-08-29 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108381378A (en) * | 2018-02-01 | 2018-08-10 | 北京派克贸易有限责任公司 | A kind of atomization ultrasound polishing method based on GaAs wafers |
| CN109370444A (en) * | 2018-12-12 | 2019-02-22 | 中国电子科技集团公司第四十六研究所 | A kind of polishing medical fluid suitable for gallium arsenide wafer polishing |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03121185A (en) * | 1989-10-03 | 1991-05-23 | Nippon Shirika Kogyo Kk | Agent for polishing surface of hard and brittle material |
| CN1316939A (en) * | 1998-07-10 | 2001-10-10 | 卡伯特微电子公司 | Polishing pad for semiconductor substrate |
| CN101781526A (en) * | 2009-01-15 | 2010-07-21 | Axt公司 | Chemical polishing solution used for GaAs chip and chemical polishing method |
-
2010
- 2010-11-02 CN CN201010531953A patent/CN102009385B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03121185A (en) * | 1989-10-03 | 1991-05-23 | Nippon Shirika Kogyo Kk | Agent for polishing surface of hard and brittle material |
| CN1316939A (en) * | 1998-07-10 | 2001-10-10 | 卡伯特微电子公司 | Polishing pad for semiconductor substrate |
| CN101781526A (en) * | 2009-01-15 | 2010-07-21 | Axt公司 | Chemical polishing solution used for GaAs chip and chemical polishing method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108381378A (en) * | 2018-02-01 | 2018-08-10 | 北京派克贸易有限责任公司 | A kind of atomization ultrasound polishing method based on GaAs wafers |
| CN109370444A (en) * | 2018-12-12 | 2019-02-22 | 中国电子科技集团公司第四十六研究所 | A kind of polishing medical fluid suitable for gallium arsenide wafer polishing |
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| Publication number | Publication date |
|---|---|
| CN102009385B (en) | 2012-08-29 |
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Address after: 101113 No.4, East 2nd Street, Tongzhou Industrial Development Zone, Beijing Patentee after: Beijing Tongmei Crystal Technology Co.,Ltd. Address before: 101113 No.4, East 2nd Street, Tongzhou Industrial Development Zone, Beijing Patentee before: BEIJING TONGMEI XTAL TECHNOLOGY Co.,Ltd. |