JP2005264321A - Film-forming method and film-forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film-forming method which reduces defect density in a formed film, by inhibiting an organic foreign matter from contaminating a film-forming chamber during film formation. <P>SOLUTION: This film-forming apparatus comprises: a load lock 12 for placing a cassette 11 which holds a wafer 10; the film-forming chamber 17 for forming the thin film on the wafer 10; and an arm 15 for transporting the wafer 10 to the film-forming chamber 17 from the load lock 12. The load lock 12 has a mass spectrometer 14 for measuring a partial pressure of the organic matter in an atmosphere in the load lock arranged therein. The film-forming method comprises the steps of: at first, discharging an atmospheric gas existing in the load lock 12 having the cassette 11 of holding the wafer 10 arranged therein, till the partial pressure of the organic matter in the atmosphere in the load lock 12 becomes 7.5×10<SP>-5</SP>mTorr or lower; transporting the wafer 10 to the film-forming chamber 17; and forming the thin film on the wafer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film used as a metal film of a semiconductor device and a film forming method and a film forming apparatus for a thin film used as an insulating film.

  In recent years, along with higher integration, higher functionality, and higher speed of semiconductor integrated circuit devices, wiring in semiconductors has become increasingly finer and thinner. For this reason, there are cases where reduction of wiring resistance, stress migration, improvement of electromigration, and the like are raised (see, for example, Patent Document 1). On the other hand, the thin film formation technique has a problem that a thin film formation defect occurs due to organic contamination, and reduction of the organic contamination is an urgent need.

  Hereinafter, an example of a conventional film forming method and film forming apparatus will be described with reference to the drawings.

  FIG. 5 is a diagram showing an outline of a conventional film forming method and film forming chamber. FIG. 6 is a diagram showing an outline of the entire film forming apparatus.

  In FIG. 5, an aluminum alloy target 52 is attached to the upper part inside the magnetron sputtering chamber 51. In order to form a metal thin film for wiring, a wafer 54 which is a semiconductor substrate is placed inside the magnetron sputtering chamber 51 so as to face the aluminum alloy target 52.

  The flange 55 connects the magnetron sputtering chamber 51 and the RGA device 53 that is a residual gas analyzer. The RGA device 53 is for evaluating impurities and impurity gas pressure inside the magnetron sputtering chamber 51.

  Next, in FIG. 6, a PEEK cassette 61 formed of a PEEK material holds wafers 54 before and after the sputtering process. A vacuum pump 64 is used to evacuate the load lock 62 in order to transport the wafer 54 from the atmosphere to the magnetron sputtering chamber 51 maintained at a high vacuum. PEEK (polyetheretherketone) is a high-strength resin in addition to excellent chemical resistance and heat resistance. Originally, a Teflon (registered trademark) cassette was used, but there was a problem of charging property, and a PP (polypropylene) cassette was used. However, PP has a problem in heat resistance and currently uses a PEEK cassette.

  The film forming method and film forming apparatus configured as described above will be described.

First, the PEEK cassette 61 is carried into the load lock 62 and evacuated to a high vacuum by the vacuum pump 64, and the wafer 54 is carried into the magnetron sputtering chamber 51. Next, when a film made of an aluminum alloy is formed on the wafer 54 by a sputtering method, the partial pressure ratio of nitrogen and oxygen contained in the argon gas in the sputtering film formation to the entire sputtering gas is about 51 ppm or less and about 11 ppm, respectively. A film made of an aluminum alloy is formed by controlling using the RGA device 53 as follows. Alternatively, the nitrogen, oxygen, and hydrogen contained in the aluminum alloy film on the wafer 54 are about 0.003 atomic% or less, about 0.01 atomic% or less, and about 0.006 atomic% or less, respectively, with respect to the entire film. It is formed so as to be controlled.
JP 2000-77359 A

  In the conventional film forming method and film forming apparatus, when an organic component is brought into the load lock, organic foreign matters adhere to the wafer before film formation or the thin film formed after the film forming process in the film forming process. The thin film and the organic foreign matter react to change the thin film into a material different from the desired film. As a result, the desired thin film cannot be removed in the etching process or cleaning process performed after the film forming process, and when the thin film is a metal thin film, a wiring defect or a gate formation defect occurs, and the thin film is an insulating film. In such a case, there is a problem in that an insulation failure between wirings is caused and a defect density is increased.

  Accordingly, an object of the present invention is to provide a film forming method and a film forming apparatus capable of reducing contamination due to the introduction of organic foreign substances from outside the film forming chamber and further reducing organic foreign substances generated from the semiconductor substrate transport cassette. It is to be.

  In order to solve the above problems, a film forming method according to claim 1 of the present invention includes a step (a) of exhausting an atmosphere in a load lock in which a cassette holding a wafer is installed, and the step (a). A step (b) of transferring the wafer to a film forming chamber later, and a step (c) of forming a thin film on the wafer after the step (b). Exhaust is performed until the partial pressure of the organic matter in the atmosphere becomes the partial pressure of the organic matter when exhausted without the cassette in the load lock.

The film forming method according to claim 2 is the film forming method according to claim 1, wherein the partial pressure of the organic substance when exhausted without the cassette is 7.5 × 10 ⁻⁵ mTorr or less.

  The film forming method according to claim 3 is the film forming method according to claim 1 or 2, wherein the organic component is cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1- At least one of hexanol, isopropenyl acetophene, glycol ester, and di-n-butyl phthalate (DBP) is included.

  5. The film forming apparatus according to claim 4, wherein a load lock for installing a cassette holding a wafer, a film forming chamber for forming a thin film on the wafer, and the wafer from the load lock to the film forming chamber. And a mass analyzer for measuring a partial pressure of an organic substance in the atmosphere in the load lock.

The film forming apparatus according to claim 5 is the film forming apparatus according to claim 4, wherein the load lock is applied until the partial pressure of the organic substance measured by the mass analyzer is 7.5 × 10 ⁻⁵ mTorr or less. Vacuum can be drawn.

  The film forming apparatus according to claim 6 is the film forming apparatus according to claim 4 or 5, wherein the material of the cassette is metal.

  The film forming apparatus according to claim 7 is the film forming apparatus according to claim 4, wherein the organic component is cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl- At least one of 1-hexanol, isopropenyl acetophene, glycol ester and di-n-butyl phthalate (DBP).

  According to the film forming method of the first aspect of the present invention, in the step (a), the partial pressure of the organic matter in the atmosphere in the load lock is the fraction of the organic matter when exhausted without the cassette in the load lock. Since the exhaust is performed until the pressure is reached, the organic foreign matter can be removed with a load lock, and the organic foreign matter can be prevented from being brought into the film formation chamber. Thereby, since the wafer surface is always kept in a state where it is not exposed to the organic foreign matter, a desired thin film can be formed and the defect density can be reduced.

According to claim 2, in the film forming method according to claim 1, the partial pressure of the organic substance when exhausted without the cassette is 7.5 × 10 ⁻⁵ mTorr or less. It is preferable.

  In Claim 3, In the film-forming method of Claim 1 or 2, the organic component is cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1-hexanol, isopropenyl acetophene. It is effective to contain at least one of glycol ester and di-n-butyl phthalate (DBP).

  According to the film forming apparatus of claim 4 of the present invention, since the mass spectrometer for measuring the partial pressure of the organic substance in the atmosphere in the load lock is installed in the load lock, the organic substance in the load lock is provided. When the partial pressure is less than or equal to a predetermined pressure, the wafer can be transferred to the deposition chamber. Thereby, it is possible to prevent organic foreign substances from being brought into the film forming chamber, and the same effect as in the first aspect can be obtained.

According to a fifth aspect of the present invention, in the film forming apparatus according to the fourth aspect, the load lock can be evacuated until the partial pressure of the organic substance measured by the mass analyzer is 7.5 × 10 ⁻⁵ mTorr or less. preferable.

  According to a sixth aspect of the present invention, in the film forming apparatus according to the fourth or fifth aspect, since the material of the cassette is a metal, the generation of organic foreign matters can be suppressed.

  According to claim 7, in the film forming apparatus according to claim 4, 5 or 6, the organic component is cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1-hexanol, isopropenyl. It is advantageous to include at least one of acetophene, glycol ester and di-n-butyl phthalate (DBP).

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of a cobalt sputtering apparatus for performing film deposition by sputtering in the presence of various impurity gases, which is a film forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, a load lock 12 for installing a cassette 11 holding a wafer 10, a film forming chamber 17 for forming a thin film on the wafer 10, and a wafer from the load lock 12 to the film forming chamber 17. And an arm 15 for transporting 10. The load lock 12 is provided with a Q-MASS (mass analyzer) 14 for measuring the partial pressure of organic matter in the atmosphere in the load lock 12.

  The wafer 10 used in this embodiment is a disk-shaped silicon substrate having a diameter of 8 inches. The metal cassette 11 can store about 25 wafers 10. The load lock 12 accommodates the metal cassette 11 transferred from the transport pod, and enables vacuuming to a desired pressure. The vacuum pump 13 evacuates the load lock 12, the transfer chamber 16 and the wafer film forming chamber 17. The Q-MASS 14 is connected to the load lock 12 and analyzes the organic components of the gas in the load lock 12 to perform wafer transfer control. The robot arm 15 is in the transfer chamber 16 and holds the wafer 10 and transfers it to a desired unit. The transfer chamber 16 uses the robot arm 15 between the load lock 12 and the film forming chamber 17 to transfer the wafer 10. The film forming chamber 17 deposits a desired thin film on the wafer 10. The load lock 12 can be opened to the atmosphere, and the wafer cassette 11 can be loaded from outside the apparatus. Further, the load lock 12, the transfer chamber 16, and the film forming chamber 17 are vacuum-separated by an openable / closable shutter.

  In addition, this figure shows the outline of an apparatus, The vacuum pump number, the number of chambers, a piping path | route, etc. are simplified and described.

  As a result of various experiments, the present inventors have found that defects due to poor formation of cobalt or an alloy film thereof depend on organic foreign matters generated in the load lock. The present invention has been obtained based on this finding.

As a first experiment, the organic foreign matter generated from the PEEK cassette as a generally used resin cassette was measured using the semiconductor manufacturing apparatus of FIG. First, a conventionally used PEEK cassette is carried into the load lock 12, evacuated by the vacuum pump 13, and the partial pressure of organic matter (AMU 50 to 150) for 5 minutes with the vacuum pump 13 stopped. It measured using Q-MASS14. Next, the cassette is not put in the load lock 12 but evacuated by the vacuum pump 13, and the partial pressure of the organic matter (AMU 50 to 150) for 5 minutes is stopped using the Q-MASS 14 while the evacuation by the vacuum pump 13 is stopped. It was measured. These results are shown in FIG. As shown in FIG. 2, in the state where the PEEK cassette is in the load lock 12, the partial pressure of the organic matter is higher than that in the state where the PEEK cassette is not in the load lock 12. That is, it can be seen that degassing of organic substances of at least 7.5 × 10 ⁻⁵ mTorr or more occurs from the PEEK cassette.

From the above results, according to the embodiment of the present invention, the wafer can be transferred when the partial pressure of the organic matter generated from the cassette is 7.5 × 10 ⁻⁵ mTorr or less when the load lock of the apparatus is evacuated. It is a form to do.

  As a second experiment, the amount of organic matter generated from the PEEK cassette and the metal cassette 11 was measured using the semiconductor manufacturing apparatus of FIG. The PEEK cassette into which the first wafer 10 is inserted is loaded into the load lock 12 and evacuated by the vacuum pump 13. After that, the load lock 12 is returned to the atmospheric pressure, and then the amount of surface organic matter on the first wafer 10. Was measured using an IN-SITU mass spectrometer. Next, the metal cassette 11 into which the second wafer 10 is inserted is loaded into the load lock 12 and evacuated by the vacuum pump 13. After that, the load lock 12 is returned to atmospheric pressure, The amount of surface organic matter attached was measured using an IN-SITU mass spectrometer. The measurement results of the first wafer 10 and the second wafer 10 measured using the IN-SITU mass spectrometer are shown in FIG.

From FIG. 3, from the surface of the PEEK cassette, cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1-hexanol, isopropenylacetophene, glycol ester, di-n-butyl phthalate ( It can be seen that organic substances such as DBP) are degassed and adhere to the surface of the first wafer 10. On the other hand, adhesion from the metal cassette 11 to the second wafer 10 is 0.04 ng / cm ² or less for cyclic siloxane (D3) and 2-ethyl-1-hexanol, respectively, and cyclic siloxane (D7, D8, D9, D11, D12). ), Isopropenyl acetophene, glycol ester, and di-n-butyl phthalate (DBP) are each suppressed to 0.01 ng / cm ² or less.

Comparing the total amount of organic matter, the amount of organic matter is about 1.30 ng / cm ² when using the PEEK cassette, while it is about 0.07 ng / cm ² when using the metal cassette 11, compared to when using the PEEK cassette. It can be seen that the amount of organic substances adhering to the second wafer 10 using the metal cassette 11 is greatly reduced.

  A comparison was made between transistor defect densities when the PEEK cassette was used under the same conditions as in the second experiment and when the metal cassette 11 was used.

  First, the third wafer 10 on which a transistor gate having a gate length of about 100 nm is formed is inserted into a PEEK cassette, loaded into a load lock 12, and then evacuated by a vacuum pump 13. Thereafter, the third wafer 10 is transferred into the film forming chamber 17 through the transfer chamber 16. In the film forming chamber 17, the third wafer 10 has a cobalt film deposited on the wafer surface by sputtering in an argon gas atmosphere. Thereafter, the third wafer 10 is returned to the PEEK cassette in the load lock 12 via the transfer chamber 16. Thereafter, the third wafer 10 is subjected to transistor formation and wiring formation, and the defect density of the transistor is measured by an inspection apparatus.

  Next, the fourth wafer 10 on which a transistor gate having a gate length of about 100 nm, which is the same as that of the third wafer 10, is inserted into the metal cassette 11, loaded into the load lock 12, and then evacuated by the vacuum pump 13. Thereafter, the fourth wafer 10 is transferred into the film forming chamber 17 through the transfer chamber 16. In the film forming chamber 17, the fourth wafer 10 has a cobalt film deposited on the wafer surface by sputtering in an argon gas atmosphere under the same conditions as the third wafer 10. Thereafter, the fourth wafer 10 is returned to the metal cassette 11 in the load lock 12 via the transfer chamber 16. Thereafter, the fourth wafer 10 is subjected to transistor formation and wiring formation under the same conditions as the third wafer 10, and the defect density of the transistor is measured by an inspection apparatus.

The defect density measurement results of the third wafer 10 and the fourth wafer 10 are shown in FIG. As can be seen from this figure, the defect density of the PEEK cassette is 0.26 cm ⁻² , whereas the defect density of the metal cassette 11 is 0.12 cm ⁻² , which is reduced by about 53.8%. This result shows that organic foreign substances react with the cobalt film on the wafer surface and cause film formation defects, resulting in transistor defects. If a desired thin film is formed by reducing organic particles, the defects are It shows that the density is reduced.

As described above, when a metal cassette is used and the load lock is brought into a vacuum state, organic contamination is reduced to 0.07 ng / cm ² or less, and thus a semiconductor device with a low defect density can be manufactured. From the above, the best mode for carrying out the present invention is that the amount of organic foreign matter adhering to the wafer surface is 0.07 ng / cm ² or less.

From the above experimental results, in the best mode of the film forming method and film forming apparatus used in the embodiment of the present invention, a pump 13 that can be evacuated is installed in the load lock 12 of the apparatus, and the wafer in the load lock 12 In this embodiment, a metal cassette 11 is used as a cassette for loading 10. Further, the wafer 10 is controlled not to be transferred to the film forming chamber 17 until the partial pressure of the organic substance when the load lock 12 is evacuated becomes 7.5 × 10 ⁻⁵ mTorr or less, and adheres to the wafer surface. The amount of the organic foreign matter is 0.07 ng / cm ² or less.

  The film forming method according to the embodiment of the present invention will be specifically described below. In FIG. 1, a metal cassette 11 containing a wafer 10 is carried into a load lock 12, and the inside of the load lock 12 is brought into a high vacuum state by a vacuum pump 13. When the load lock 12 is in a high vacuum state, the partial pressure of the gas in the load lock 12 is measured by the Q-MASS 14. The wafer 10 is transferred to the transfer chamber 16 by the robot arm 15 according to the measurement result of the Q-MASS 14. The wafer 10 transferred to the transfer chamber 16 by the robot arm 15 is transferred to the film forming chamber 17 to deposit a desired thin film.

In this embodiment, after the inside of the load lock 12 of the apparatus is evacuated, the partial pressure in the load lock 12 is measured by the Q-MASS 14, and the partial pressure of AMU corresponding to organic contamination is 7.5 × 10. The atmosphere in the load lock 12 is evacuated until ⁻⁵ mTorr or less, and the wafer 10 is controlled not to be transferred to the film forming chamber 17.

In order to prevent degassing, which is an organic contamination generated from the wafer transport cassette when the internal pressure of the load lock of the device is evacuated, a metal cassette is used, but organic contamination that adheres to the wafer surface If it is made of a material having an amount of 0.07 ng / cm ² or less, the material is not particular.

  A film forming method and a film forming apparatus according to the present invention have effects of reducing organic foreign matters in a load lock and reducing the defect density of a thin film formed in a semiconductor device, and are used for semiconductor manufacturing. It is useful as a method and a film forming apparatus.

It is a figure which shows the outline of the sputtering device in embodiment of this invention. It is a figure which shows the time change of the partial pressure of the organic component in a load lock. It is a figure which shows the amount of organic particles in each cassette. It is a figure which shows the defect density in each cassette. It is a figure which shows the cross section of the conventional film-forming chamber. It is a figure which shows the outline of the conventional film-forming apparatus.

Explanation of symbols

10 Wafer 11 Metal cassette 12 Load lock 13 Vacuum pump 14 Q-MASS
DESCRIPTION OF SYMBOLS 15 Robot arm 16 Transfer chamber 17 Deposition chamber 51 Magnetron sputter chamber 52 Aluminum alloy target 53 RGA apparatus 54 Wafer 55 Flange 61 PEEK cassette 62 Load lock 64 Vacuum pump

Claims (7)

Evacuating the atmosphere in the load lock where the cassette holding the wafer is installed;
A step (b) of transferring the wafer to a film forming chamber after the step (a);
And (c) forming a thin film on the wafer after the step (b)
In the step (a), exhaust is performed until the partial pressure of the organic matter in the atmosphere in the load lock becomes the partial pressure of the organic matter when exhausted without the cassette in the load lock. Film forming method. 2. The film forming method according to claim 1, wherein a partial pressure of the organic substance when exhausted in a state where the cassette is not contained is 7.5 × 10 ⁻⁵ mTorr or less.   The organic component is a cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1-hexanol, isopropenylacetophene, glycol ester, and di-n-butyl phthalate (DBP). The film-forming method of Claim 1 or 2 containing at least one. A load lock for installing the cassette holding the wafer;
A film forming chamber for forming a thin film on the wafer;
An arm for transferring the wafer from the load lock to the film formation chamber;
The film forming apparatus, wherein the load lock is provided with a mass analyzer for measuring a partial pressure of an organic substance in an atmosphere in the load lock. 5. The film forming apparatus according to claim 4, wherein the load lock can be evacuated until a partial pressure of the organic substance measured by the mass analyzer becomes 7.5 × 10 ⁻⁵ mTorr or less.   6. The film forming apparatus according to claim 4, wherein the cassette is made of metal.   The organic component is a cyclic siloxane (D3, D7, D8, D9, D11, D12), 2-ethyl-1-hexanol, isopropenylacetophene, glycol ester, and di-n-butyl phthalate (DBP). 6. The film forming apparatus according to claim 3, 4 or 5, comprising at least one.

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