JP2002043259A - Composition for polishing metal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal polishing composition for polishing a metal film at a high speed, which is superior in polishing selectivity of the metal film and an insulation film and can suppress defects such as scratches, dishing, etc., on the polished surface in a process of planarizing the metal film on the semiconductor substrate, a method of planarizing the metal film on the substrate using the composition, and a method of manufacturing a semiconductor substrate. SOLUTION: The metal polishing composition contains at least one kind of abrasive as a main component, a polishing assistant of at least one kind selected from ammonia or ammonium salts, water and low-crystalline fine cellulose as required. The abrasive is selected from a group of iron oxide (III) and composite materials of iron oxide (III) with at least one kind selected from alumina, ceria, germania, silica, titania and zirconia.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polishing a metal film formed on a semiconductor substrate at a high speed without causing defects.
In addition, a polishing composition having excellent polishing selectivity for a metal film / insulating film and obtaining a polished surface with extremely high flatness, a method for planarizing a metal film on a semiconductor substrate using the same, and a method for manufacturing a semiconductor substrate About.

[0002]

2. Description of the Related Art With the rapid development of LSI technology, integrated circuits have been increasingly miniaturized and multilayered. Multi-layer wiring in integrated circuits greatly increases the unevenness of the semiconductor surface, which, in conjunction with the miniaturization of integrated circuits, results in disconnection, lowering of electric capacity, occurrence of electromigration, etc., resulting in lower yield and lower reliability. Causing problems. For this reason, various processing techniques for planarizing metal wirings and interlayer insulating films in a multilayer wiring board have been developed so far, and one of them is CMP (Chemical Mechanical Engineering).
There is chanicalPolishing (chemical mechanical polishing) technology. C
MP technology is used in semiconductor manufacturing to flatten interlayer insulating films,
This technology is necessary for forming embedded wiring and plugs.

[0003] CMP is generally performed by mounting a flat wafer made of a semiconductor material on a polishing platen and rotating each of the polishing platen and the polishing pad while pressing the polishing platen against a wet polishing pad with a constant pressure. At this time, the projections of the wiring and the insulating film are polished and flattened by the polishing composition introduced between the wafer and the polishing pad.

Conventionally, various polishing compositions and polishing methods have been proposed for polishing a metal film on a semiconductor substrate.
For example, as a polishing composition for a metal film such as aluminum formed on a semiconductor substrate, a polishing composition obtained by dispersing aluminum oxide in a nitric acid aqueous solution having a pH of 3 or less (US Pat. No. 4,702,792); There is a polishing composition (US Pat. No. 4,944,836) in which aluminum oxide or silicon oxide is mixed with an acidic aqueous solution of sulfuric acid, nitric acid, acetic acid or the like. Also, a polishing composition in which aluminum oxide is dispersed in an aqueous solution of hydrogen peroxide and phosphoric acid (US Pat. No. 5,209,8)
No. 16), a polishing composition comprising an abrasive such as aluminum oxide or silicon oxide and an oxidizing agent such as hydrogen peroxide is generally used. However, when aluminum oxide is used for flattening a metal film on a semiconductor substrate, swelling ^
Although high polishing rates were obtained, defects such as micro scratches and orange peel sometimes occurred on the surfaces of metal films and insulating films. On the other hand, when a polishing material such as satin, amorphous alumina or silicon oxide is used, it is possible to suppress the occurrence of defects such as micro scratches and orange peel on the surface of the metal film or the insulating film. There was a problem that a sufficient polishing rate could not be obtained. Further, in the case of silicon oxide, the surface charge becomes unstable in an acidic region, so that agglomeration of particles occurs, and there is a problem that surface defects such as micro scratches are easily generated. In addition, when hydrogen peroxide as a liquid oxidizing agent is used as described above, or when a metal etchant such as ammonium persulfate is used (Japanese Patent Application Laid-Open No. 6-313164), the wet etching is excessively advanced. Dishing and pits,
There was a problem in practical use such as generation of defects such as voids.

In Japanese Patent Application Laid-Open No. 10-163141,
Polishing compositions containing an iron (III) compound together with water and a polishing agent selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, silicon nitride, and zirconium oxide have been proposed. It is said that the polishing rate of copper is higher and the occurrence of scratches and etching is smaller than that of copper. However, in order to increase the polishing rate and increase the productivity, a large amount of a polishing accelerator such as an iron (III) compound is used, and the polishing conditions, for example, the load are increased. The occurrence cannot be prevented.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a metal film on a semiconductor substrate is polished at a high speed, the flatness of a step portion and the uniformity on a wafer surface are excellent, and the dispersion stability of polishing fine particles is extremely high. A polishing composition for a metal film, which suppresses the occurrence of defects on the surface to be polished because it is good and can suppress etching performance, and has excellent polishing selectivity for a metal film / insulating film, and planarization using the same. It is an object to provide a method and a method for manufacturing a semiconductor substrate.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that (A) iron oxide (I)
II) and an abrasive comprising at least one selected from the group consisting of a composite material of iron (III) oxide and at least one selected from alumina, ceria, germania, silica, titania, and zirconia; The present invention has been found that a polishing composition comprising at least one polishing aid selected from ammonia or ammonium salt and (C) water is effective for polishing a metal film on a substrate. Was reached.

That is, the present invention firstly comprises (A) a composite material of iron (III) oxide and iron (III) oxide and at least one selected from alumina, ceria, germania, silica, titania and zirconia. A polishing composition comprising: at least one abrasive selected from the group consisting of: (B) at least one abrasive selected from ammonia or ammonium salts; and (C) water. Secondly, selected from the group consisting of (A) iron (III) oxide and a composite material of iron (III) and at least one selected from alumina, ceria, germania, silica, titania, and zirconia. (B) a polishing aid consisting of at least one kind selected from ammonia or ammonium salt, and And (C) a method for planarizing a metal film on a semiconductor substrate, characterized by using a polishing composition comprising water. Thirdly, (A) iron (III) oxide and iron oxide. An abrasive comprising at least one selected from the group consisting of a composite material of (III) and at least one selected from alumina, ceria, germania, silica, titania, and zirconia; (B) an ammonia or ammonium salt The present invention also provides a method for producing a semiconductor substrate, characterized by using a polishing composition comprising at least one polishing aid and water (C).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The metal film polishing composition of the present invention comprises (A) a composite material of iron (III) oxide and iron (III) oxide and at least one selected from alumina, ceria, germania, silica, titania, and zirconia. A polishing agent comprising at least one abrasive selected from the group consisting of: (B) at least one abrasive selected from ammonia or ammonium salts; and (C) water.

The abrasive used in the present invention is iron oxide (II).
And particles composed of a composite material of iron (III) oxide and at least one selected from the group consisting of alumina, ceria, germania, silica, titania and zirconia. Iron oxide (II
Examples of I) include ferrite such as triiron tetroxide, lithium iron oxide, and zinc iron oxide, in addition to iron sesquioxide. In the case of using particles of iron oxide (III) alone as the abrasive, a generally known method can be used for the production method. For example, in the case of iron sesquioxide, a method of baking iron sulfate at a high temperature, a method of heating iron hydroxide, a method of baking iron nitrate, and the like can be mentioned.

On the other hand, when a composite material of iron (III) oxide and at least one selected from the group consisting of alumina, ceria, germania, silica, titania and zirconia is used as an abrasive, solid phase reaction, coprecipitation, A known method such as a method, an impregnation method, and a gas phase method can be applied. For example, in the case of a composite material with silica, a method in which silica particles such as fumed silica and colloidal silica are added to iron nitrate in an appropriate dispersion medium and then calcined to form a composite, or an aqueous solution of ammonium iron sulfate in silica powder Impregnated and then calcined, and a coordination chemical sol-gel method in which the rate of hydrolysis of both raw material alkoxides is controlled to prepare a homogeneous composite oxide.

Generally, the abrasive used in the polishing composition of the present invention preferably has an average particle diameter of about 15 μm or less as measured by a light scattering method. The present invention provides a composition for polishing a metal film according to the present invention, comprising: iron (III) oxide;
(III) and at least one abrasive selected from the group consisting of a composite material of at least one selected from alumina, ceria, germania, silica, titania, and zirconia, together with an abrasive selected from ammonia or ammonium salts At least one polishing aid is used by being dispersed / dissolved in water. Examples of the above ammonium salts include ammonium carbonate, ammonium bicarbonate, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium perchlorate, ammonium borate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium nitrate, and ammonium sulfate. Ammonium sulfate, ammonium persulfate, ammonium thiosulfate, ammonium chromate, ammonium nitrate such as cerium nitrate, ammonium sulfate such as ammonium chromium sulfate, ammonium manganese sulfate, ammonium molybdate, ammonium tungstate, ammonium tungstophosphate, ammonium vanadate, heteropoly Ammonium salts of acids, inorganic ammonium compounds such as ammonium hexachloroplatinate, and benzoic acid Ammonium, ammonium citrate, ammonium salts of organic acids such as ammonium tartrate can be exemplified. The concentration of these ammonia or ammonium salts is not particularly limited,
It may be completely dissolved or partially insoluble.

[0013] Among them, ammonium carbonate and the like are one example that is preferably used. However, it is not clear what mechanism the polishing material containing iron oxide and the polishing aid use to polish a metal film such as copper. Is estimated as follows. Ammonium carbonate itself does not have the property of dissolving metallic copper, but when the surface of copper comes into contact with iron oxide, the contact surface becomes copper oxide, and a polishing aid such as ammonium carbonate acts on this, We believe that the melting will cause polishing.

In other words, unlike the polishing composition of the present invention, which is different from the conventional method in which an oxidizing agent such as hydrogen peroxide is allowed to act on copper and the copper is scraped off with polishing particles, the polishing particles are formed in contact with the polishing particles. Since it is a method of dissolving and removing a portion presumed to be copper oxide with a polishing aid, dishing is considered to be difficult to place, and it can be said that this is an extremely effective method of polishing a metal film.

The metal film polishing composition of the present invention includes:
Low crystalline fine cellulose can be contained. As a result, the dispersion stability of the abrasive particles is improved, scratches on the polished surface due to particle aggregation are suppressed, and the polishing selectivity of the metal film / insulating film is also improved. In addition, the moderate thickening effect improves the retention of the slurry particles on the polished surface, thereby reducing the amount of slurry consumption, and further improving the dispersibility, so that the used slurry can be reused after being recovered, thereby reducing costs. The feature that is also exhibited. The cellulose used in the present invention has an average degree of polymerization (DP) of 100 or less, a fraction of cellulose I-type crystal component of 0.1 or less, and a fraction of cellulose II-type crystal component of 0.4 or less. It is characterized by a low degree of polymerization and a low crystallinity, in which the average particle size of the cellulose particles is 5 μm or less. Here, the average degree of polymerization (DP) is determined by measuring the specific viscosity of a diluted cellulose solution obtained by dissolving a dried cellulose sample in cadoxene using an Ubbelohde viscometer (25 ° C.), and calculating from the intrinsic viscosity number [η] the following viscosity formula (1). And the value calculated by the conversion formula (2). [η] = 3.85 × 10 ⁻² × MW ^0.76 (1) DP = MW / 162 (2)

Further, the fraction of the cellulose I-type crystal component (χ
_T ) means that a wide-angle X obtained by drying a cellulose dispersion, pulverizing a sample into a powder, forming a tablet, and using a reflection method with a radiation source CuKα is used.
In the line diffraction diagram, the following (3) is obtained from the absolute peak intensity h ₀ at 2θ = 15.0 ° attributed to the (110) plane peak of the cellulose type I crystal and the peak intensity h ₁ from the baseline at this plane interval. Means the value obtained by the formula. Also, the fraction of cellulose II type crystal component (χ
_II ) Similarly, a dried cellulose sample is pulverized into a powder, formed into a tablet, and assigned to the (110) plane peak of the cellulose II crystal in a wide-angle X-ray diffraction pattern obtained by a reflection method using a radiation source CuKα. The value obtained from the absolute peak intensity h ₀ * at 2θ = 12.6 ° and the peak intensity h ₁ * from the baseline at this plane interval is determined by the following equation (4). _{Ｉ I} = h ₁ / h ₀ (3) _{ＩＩ II} = h ₁ * / h ₀ * (4)

The above average particle diameter of cellulose is a value measured by a light scattering method such as a laser diffraction method in a state where the association between particles in water is cut as much as possible. Was diluted with water so as to be about 0.5% by weight, and then mixed for 10 minutes with a blender having a capacity of 15,000 rpm or more to obtain a uniform dispersion, which was then subjected to ultrasonic treatment for 30 minutes. Measured. The content of the above-mentioned cellulose varies depending on the conditions of the pad or the like to be used, but is generally used in the range of 0.1 to 5% by weight based on the total weight of the composition. If the amount is less than 0.1% by weight, the effect of the addition cannot be sufficiently obtained. If the amount exceeds 5% by weight, the viscosity of the obtained composition becomes too high, and handling problems occur.

The polishing composition of the present invention may contain a known oxidizing agent. The use of an oxidizing agent is expected to improve the polishing rate of the metal film within a range that does not cause over-etching, and to prevent uneven elution of the polished metal film. Examples of the oxidizing agent to be contained include known oxidizing agents such as peroxide, perchloric acid, perchlorate, iodic acid, iodate, persulfate, persulfate, and nitrate. The metal film polishing composition of the present invention is used in the form of a slurry dispersed in water. Examples of the dispersion method for forming a slurry include a dispersion method using a homogenizer, ultrasonic waves, a wet medium mill, or the like. The slurry concentration (the content of the abrasive in the metal film polishing composition) is usually about 1 to 30% by weight. If necessary, known dispersants such as ammonium polycarboxylate and ethanol, n-propanol, iso-propanol, ethylene glycol,
Water-soluble alcohols such as glycerin, surfactants such as alkylbenzenesulfonates, and chelating agents such as ethylenediaminetetraacetate and gluconate can also be added.

The polishing composition for polishing a metal film of the present invention thus prepared is applied to polishing and flattening of a metal film formed on a semiconductor substrate. The metal film on the semiconductor substrate to be polished is a known metal film for wiring, plug, contact metal layer, and barrier metal layer, for example, aluminum, copper, tungsten, titanium, tantalum, aluminum alloy, copper alloy. And a metal film selected from the group consisting of titanium nitride, tantalum nitride and the like. In particular, application to a metal film made of copper and a copper alloy having a low surface hardness and easily causing defects such as scratches and dishing is recommended.

The method for planarizing a metal film on a semiconductor substrate according to the present invention comprises irradiating a polishing composition comprising the above-mentioned abrasive having photocatalytic performance and water as essential components with actinic rays upon use. The upper metal film is polished and flattened. Hereinafter, a method of flattening the metal film will be described. As shown in FIG. 1C, a semiconductor substrate obtained by embedding a metal film 5 for wiring is shown in FIG.
As shown in (D), an excess metal film other than the groove or the opening is polished by using a metal film polishing composition containing an abrasive having photocatalytic performance and water, thereby removing the metal film and flattening. I do.

According to the method of manufacturing a semiconductor substrate of the present invention, a metal film on a semiconductor substrate such as a silicon substrate is polished using a polishing material having photocatalytic performance and a metal film polishing composition containing water as essential components. It is characterized by. Hereinafter, a method for manufacturing a semiconductor substrate will be described. First, as shown in FIG. 1A, after an insulating film 2 is formed on a semiconductor substrate 1 such as a silicon substrate, a groove for metal wiring or a wiring for connection wiring is formed in the insulating film 2 by photolithography and etching. An opening is formed. Next, as shown in FIG. 1B, a barrier metal layer 3 made of titanium nitride (TiN), tantalum nitride (TaN), or the like is formed in the groove or opening formed in the insulating film 2 by a method such as sputtering or CVD. I do.
Next, as shown in FIG. 1C, the metal film 4 for wiring is buried so that the thickness is equal to or larger than the height of the groove or opening formed in the insulating film 2. Next, as shown in FIG. 1 (D), excess metal film other than the grooves or openings is removed by a polishing method using a polishing material having photocatalytic performance and a metal film polishing composition containing water as an essential component. . Furthermore, a semiconductor substrate having a multilayer wiring structure as an electronic component can be obtained by repeating the above method a required number of times. Note that the metal film on the semiconductor substrate can be polished by the above-described metal film polishing composition or the method for planarizing a metal film when the semiconductor substrate is manufactured.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[0023]

[Production Example 1] <Preparation of abrasive> Abrasive A: fumed silica powder (AEROSI)
L50 / Nippon Aerosil Co., Ltd .: Average particle size 20 nm
(Catalog value)) 30 g of a 30% aqueous solution of iron nitrate was added in small portions while shaking the container, and the container was impregnated. The obtained powder was calcined in an electric furnace at 450 ° C. for 5 hours in the presence of air to obtain iron oxide (I).
II) A composite silica powder was obtained.

[0024]

[Production Example 2] <Preparation of Abrasive> Abrasive B: 300 parts of silica sol having a solid content of 10 wt% (trade name: Snowtex 30, manufactured by Nissan Chemical Co., Ltd.)
A powder obtained by spray-drying a liquid in which 16 parts of iron (III) nitrate nonahydrate was dissolved by a spray drier was calcined in an electric furnace at 700 ° C. for 5 hours in the presence of air to obtain iron (III) oxide. ) A composite silica powder was obtained.

[0025]

[Production Example 3] <Preparation of low crystalline fine cellulose> Wood pulp was dissolved in 65% by weight sulfuric acid at -5 ° C so that the pulp content was 4% by weight, and this cellulose / sulfuric acid solution was 2.7 times. The cellulose was poured into a volume of water under vigorous stirring to precipitate the cellulose. After hydrolyzing the obtained flaky cellulose dispersion at 80 ° C. for 40 minutes, it was filtered and washed with water to obtain an aqueous dispersion of paste-like cellulose fine particles. Next, ion-exchanged water was added to the gel to make the cellulose concentration 4.0% by weight, and then 15,000 using a blender.
The mixture was treated four times at rpm at a processing pressure of 1,750 kg / cm ² using an ultra-high pressure homogenizer for 5 minutes to obtain a highly transparent gelled cellulose dispersion. The cellulose thus obtained has an average particle diameter of 0.24 μm, the cellulose I-type crystal component of the cellulose particles and the cellulose II.
The mold component fractions were 0.03 and 0.16, respectively.

[0026]

Example 1 Ferric oxide (manufactured by Wako Pure Chemical Industries, Ltd.) was used as an abrasive, mixed with water so that the abrasive concentration was 10% by weight, ammonium carbonate was 5% by weight, and the cellulose concentration was the total amount of the slurry. The low-crystalline fine cellulose prepared above was added so as to be 1.5% by weight of the mixture, and dispersed using a stirrer and an ultra-high pressure homogenizer to prepare a slurry for polishing a metal film. Using this slurry, each of the copper film and the silicon oxide film was polished, and a series of polishing performance evaluations shown below were performed. Polishing, processing pressure 3
00 g / cm ² , platen rotation speed 200 rpm, I
C1400 (trade name, manufactured by Rodel Nitta) was performed under the conditions. Table 1 shows the evaluation results.

[0027]

Example 2 The abrasive A (average particle diameter 0.8 μm) obtained in Production Example 1 was mixed with water so that its concentration became 15% by weight, and then finely dispersed using an ultra-high pressure homogenizer. went. Next, ammonium chloride was dissolved therein so as to be 7% by weight to prepare a metal polishing slurry. Using this slurry, the polishing performance was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0028]

Example 3 Abrasive A (average particle size 0.8 μm) obtained in Production Example 1 was mixed with water so that the concentration was 10% by weight, and then the cellulose concentration was adjusted to 1.50 with respect to the total amount of the slurry. The low-crystalline fine cellulose prepared in Production Example 3 was added so as to have a concentration of 5 wt%, and a fine dispersion treatment was performed using an ultrahigh-pressure homogenizer. Then, ammonium chloride was added to this and added to 10 wt% to dissolve it, thereby preparing a metal polishing slurry. Using this slurry, the polishing performance was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0029]

Example 4 A polishing slurry was prepared in the same manner as in Example 1 except that abrasive B (average particle diameter 0.5 μm) was used.
The polishing performance was evaluated using this. Table 1 shows the results.

[0030]

Comparative Example 1 Fumed silica powder (AEROSIL5)
0 / Nippon Aerosil Co., Ltd .: average particle diameter of 20 nm) was mixed with water so as to have a concentration of 10% by weight, and then dispersed using a stirrer and an ultra-high pressure homogenizer to remove ammonium chloride. It melt | dissolved so that it might become weight%, and the slurry for metal polishing was adjusted. Using this slurry, the polishing performance was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0031]

Comparative Example 2 The polishing performance was evaluated in the same manner as in Example 1 except that alumina (aluminum oxide C, manufactured by Nippon Aerosil Co., Ltd.) was used as the abrasive. Table 1 shows the results. <Evaluation of polishing performance> Measurement of polishing rate: Calculated by dividing the change in each film thickness before and after polishing by the polishing time.・ Evaluation of step smoothness: First, 0.2 on silicon wafer
A copper film having a thickness of μm is formed, and a 0.3 μm thick
A copper film substrate having a step was formed by forming a μm copper film. From each polishing rate obtained above, 0.3 μ
After polishing for the time required to polish the m-th copper film, the level difference on the substrate was measured to evaluate the level difference smoothness.・ Surface defect (scratch) evaluation: After polishing, the wafer was washed and dried, spot light was applied in a dark room, and the presence or absence of scratch was visually determined.

Dishing evaluation: Wet etching property, which is the cause of dishing, was evaluated as a substitute for dishing characteristics. That is, the wafer with the copper film was immersed in the slurry for a certain period of time, the change in film thickness before and after immersion was measured, and the change in the film thickness was divided by the immersion time to determine the etching rate, which was evaluated according to the following criteria. ：: etching rate of less than 0.5 nm / min ○: etching rate of 0.5 to 1 nm / min ：: etching rate of 1 to 10 nm / min ×: etching rate of more than 10 nm / min

Dispersion stability of slurry particles: After leaving at room temperature for one month, the dispersibility of abrasive particles in the slurry was visually evaluated. ：: good dispersibility without sedimentation of particles △: slight sedimentation or uneven concentration of particles ×: Sedimentation of particles or uneven concentration

From the results shown in Table 1, it can be seen that the polishing composition of the present invention has a higher polishing rate of a copper film than an oxide film and is excellent in step flattening property. Further, it can be seen that there is no occurrence of defects such as scratching and dishing, and the dispersion stability of the abrasive particles in the slurry is excellent.

[0035]

[Table 1]

[0036]

The composition for polishing a metal film of the present invention is a composite of iron (III) oxide and iron (III) oxide with at least one selected from alumina, ceria, germania, silica, titania, and zirconia. It contains at least one abrasive selected from the group consisting of materials, a polishing aid selected from ammonia or an ammonium salt, water, and, if necessary, contains low-crystalline fine cellulose, thereby enabling high-speed Cu The film can be polished and the metal / insulating film has excellent polishing selectivity. Furthermore, since the abrasive itself has a chemical polishing action, it has excellent step flattening performance, and can polish a metal film on a semiconductor substrate that can suppress the occurrence of defects such as scratching and dishing due to good particle dispersibility. The present invention has found a material having extremely useful performance in performing the method, and its industrial use value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of forming a metal wiring using a CMP technique.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 insulating film 3 barrier metal layer 4 metal film

Claims (6)

[Claims] (A) Iron (III) oxide, and iron oxide
An abrasive comprising at least one selected from the group consisting of a composite material of (III) and at least one selected from alumina, ceria, germania, silica, titania, and zirconia; (B) an ammonia or ammonium salt A polishing composition for a metal film, comprising: a polishing aid comprising at least one selected from the group consisting of: and (C) water. 2. The polishing composition for a metal film according to claim 1, further comprising (D) cellulose particles. 3. The cellulose particles having an average degree of polymerization (D)
P): 100 or less, the fraction of cellulose type I crystal component is 0.1 or less, and the fraction of cellulose type II crystal component is 0.4
3. The polishing composition for a metal film according to claim 2, wherein the average particle diameter of the constituent cellulose particles is 5 μm or less. 4. The method according to claim 1, wherein the metal film is aluminum on a semiconductor substrate,
4. The composition for polishing a metal film on a semiconductor substrate according to claim 1, wherein the composition is a metal film selected from copper, tungsten, titanium, tantalum, an aluminum alloy, a copper alloy, titanium nitride, and tantalum nitride. 5. A method for planarizing a metal film on a semiconductor substrate, comprising using the polishing composition for a metal film according to claim 1. 6. A method for producing a semiconductor substrate, comprising using the polishing composition for a metal film according to claim 1.