JP5384165B2 - Substrate processing method - Google Patents

Description

  The present invention relates to a substrate processing method, and more particularly to a substrate processing method using an organic compound gas.

  In a semiconductor device having a low dielectric constant insulating film (Low-k film) as an interlayer insulating film and a copper (Cu) wiring layer or a copper alloy wiring layer as an internal wiring layer, removing Cu-containing residue after etching In addition, residue removal using an organic compound gas, for example, organic acid dry cleaning has attracted attention (for example, Non-Patent Document 1).

  In organic acid dry cleaning, it has been confirmed that Cu-containing residues can be removed in a single wafer type apparatus. Further, in order to reduce the thermal load on the Cu wiring and the low-k film, it is desirable that the organic acid dry cleaning be performed by a low temperature process.

H. Kudo, et al. Proceeding of IITC 2008, p93-95, “EnhancingYield and Reliability by Applying Dry Organic Acid Vapor Cleaning to CopperContact Via-Bottom for 32-nm Nodes and Beyond”, (2008)

  It takes time to completely remove the Cu-containing residue using a single wafer type apparatus and a low temperature process. For this reason, the throughput decreases.

  On the other hand, when organic acid dry cleaning is performed using a batch type apparatus, a high throughput can be achieved even in a low temperature process as compared with a single wafer type apparatus.

  However, there is a situation that the volatilized Cu-containing residue easily adheres to an adjacent substrate, for example, the back surface of the wafer. The wafer is generally silicon (Si), but Cu is known to be very easy to diffuse in Si. If the Cu-containing residue adheres to the back surface of the wafer and diffuses inside the wafer, the operation performance of the transistor may be deteriorated.

  The present invention has been made in view of the above circumstances, and enables substrate processing using an organic compound gas at a low temperature process and at a high throughput while reducing the possibility of causing deterioration in the operation performance of the transistor. It aims to provide a method.

In order to solve the above-described problem, a substrate processing method according to a first aspect of the present invention is a substrate processing method for a substrate to be processed having a thin film containing copper or a copper alloy. A dummy substrate and a substrate boat having a plurality of substrates to be processed holding units alternately held, and the substrate substrate boat in which the substrate to be processed and the dummy substrate are alternately held. Using the organic compound gas with respect to the plurality of substrates to be processed held in the substrate boat to be processed in the processing vessel. Performing a chemical dry treatment on the thin film containing copper or copper alloy, and the steps are performed in the order described above .

A substrate processing method according to a second aspect of the present invention is a substrate processing method for a substrate to be processed having a thin film containing copper or a copper alloy, and a plurality of substrates to be processed are arranged in a plurality of stages. A step of holding the substrate to be processed alternately in front and back, and a step of carrying the substrate to be processed in which the substrate to be processed is alternately held into a processing container for performing a dry process using an organic compound gas. In the processing container, the organic compound gas is used for the plurality of substrates to be processed held by the substrate substrate boat, and a chemical dry process is performed on the thin film containing copper or copper alloy. And performing the steps, and the steps are performed in the order described above .

  According to the present invention, it is possible to provide a substrate processing method capable of performing substrate processing using an organic compound gas at a low temperature process and at a high throughput while reducing the possibility of causing deterioration in the operation performance of the transistor.

Sectional drawing which showed roughly an example of the substrate processing apparatus which can perform the substrate processing method which concerns on one Embodiment of this invention Sectional drawing which shows the state which removed the wafer boat from the processing container Diagram showing an example of organic compound gas supply mechanism The figure which shows typically an example of arrangement | positioning of the wafer to the wafer boat employ | adopted in the substrate processing method which concerns on one Embodiment. The figure which shows typically arrangement | positioning of the wafer to the wafer boat which concerns on a reference example. Sectional drawing which shows one cross-sectional example of element formation surface Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment Sectional drawing which shows an example of the manufacturing method of the semiconductor device which can utilize the substrate processing method which concerns on one Embodiment The figure which shows typically an example of arrangement | positioning of the wafer to the wafer boat employ | adopted in the substrate processing method which concerns on one Embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In this description, the same parts are denoted by the same reference symbols throughout the drawings to be referred to.

(Device configuration)
FIG. 1 is a cross-sectional view schematically showing an example of a substrate processing apparatus capable of executing a substrate processing method according to an embodiment of the present invention. This example is a substrate processing apparatus used for manufacturing a semiconductor device, for example, a dry cleaning apparatus that removes copper oxide from the surface of a thin film containing copper or a copper alloy formed on a semiconductor wafer (hereinafter referred to as a wafer). Illustrate. However, this invention can be applied not only to dry cleaning but also to etching of copper oxide. The present invention is not limited to the manufacture of semiconductor devices.

  The dry cleaning apparatus 100 includes a cylindrical processing container 1 having a ceiling with a lower end opened. The entire processing container 1 is made of, for example, quartz, and a ceiling plate 2 made of quartz is provided on the ceiling in the processing container 1 and sealed. For example, a manifold 3 formed in a cylindrical shape using stainless steel is connected to a lower end opening of the processing container 1 via a seal member 4 such as an O-ring.

  The manifold 3 supports the lower end of the processing container 1, and a quartz wafer boat 5 capable of holding a plurality of, for example, 50 to 100 wafers W as multi-stages from below the manifold 3 is processed. It can be inserted into the container 1. A state where the wafer boat 5 is detached from the processing container 1 is shown in FIG. The wafer boat 5 has a plurality of pillars 6 in which a plurality of grooves are formed. The plurality of wafers W are held on the support 6 by inserting the edges of the wafers W into the grooves.

  The wafer boat 5 is placed on a table 8 via a quartz heat insulating cylinder 7. The table 8 is supported on a rotating shaft 10 that opens and closes a lower end opening of the manifold 3 and penetrates a lid portion 9 made of, for example, stainless steel.

  For example, a magnetic fluid seal 11 is provided at the penetrating portion of the rotating shaft 10 and supports the rotating shaft 10 so as to be rotatable while hermetically sealing. A seal member 12 made of, for example, an O-ring is interposed between the peripheral portion of the lid portion 9 and the lower end portion of the manifold 3, thereby maintaining the sealing performance in the processing container 1.

  The dry cleaning apparatus 100 includes an organic compound gas supply mechanism 13 that supplies an organic compound gas, for example, formic acid (HCOOH) gas, into the processing container 1 as a processing gas used for dry cleaning, that is, removal of copper oxide. doing. The organic compound gas supply mechanism 13 is connected to the gas pipe 14. FIG. 3 shows an example of the organic compound gas supply mechanism 13.

  As shown in FIG. 3, the organic compound gas supply mechanism 13 supplies an organic compound that serves as a gas source of the organic compound gas, in this example, a gas source storage unit 131 that stores formic acid, and a vaporized organic compound gas. A supply line 132 that leads from the source reservoir 131 to the gas pipe 14, a mass flow controller (MFC) 133 that adjusts the flow rate of the organic compound gas that flows through the supply line 132, and a valve 134 are provided. The gas source storage unit 131, the supply line 132, the MFC 133, and the valve 134 are provided with a heater 135 that heats and vaporizes the organic compound gas to a predetermined temperature. The heater 135 may also be provided in the gas pipe 14 as shown in FIG. The gas pipe 14 penetrates the side wall of the manifold 3 and is connected to a dispersion nozzle 15 made of a quartz tube that is bent upward and extends vertically inside the manifold 3. A plurality of gas discharge holes 15 a are formed at predetermined intervals in the vertical portion of the dispersion nozzle 15, and the horizontal direction is directed from the gas discharge holes 15 a toward the wafers W placed on the wafer boat 5. In addition, an organic compound gas such as formic acid gas can be discharged.

  A cylindrical heating device 16 is provided on the outer periphery of the processing container 1. The heating device 16 is provided so as to surround the processing container 1 and heats the wafer W accommodated in the processing container 1.

  Although not shown in FIGS. 1 and 2, an exhaust port for evacuating the inside of the processing container 1 is provided in a portion of the processing container 1 opposite to the dispersion nozzle 15. .

(Substrate processing)
Next, an example of a substrate processing method according to an embodiment of the present invention will be described.

  FIG. 4 is a diagram schematically showing an example of the arrangement of the wafers W on the wafer boat 5 employed in the substrate processing method according to one embodiment of the present invention.

  As shown in FIG. 4, in one example, a wafer boat 5 having a plurality of wafers W and a plurality of dummy wafers DW, a plurality of stages of substrate holding units, in this example, a column 6 having a plurality of grooves 6 a. And hold them alternately.

  Incidentally, normally, as in the reference example shown in FIG. 5, the plurality of wafers W are held one by one in the groove 6 a of the support column 6. In such an arrangement of the wafer W, the front surface of the wafer W, that is, the element formation surface 200 on which the semiconductor elements are formed faces the back surface of another wafer W having the element formation surface 200. For example, as shown in FIG. 6, the element formation surface 200 includes a semiconductor element, for example, a transistor 201, an internal wiring 203 containing copper or a copper alloy that is electrically connected to the source and drain 202 of the transistor 201, and the like. It is formed. For this reason, when the Cu-containing residue (for example, copper oxide 207 or 207a) generated from the internal wiring 203 containing, for example, copper or a copper alloy in the element formation surface 200 is removed, the scattered copper is separated from another wafer W. There is a possibility that the attached copper adheres to the back surface and diffuses into the inside of another wafer W. If copper diffuses into the inside of the wafer W, there is a possibility that the operation performance of the transistor is deteriorated.

  In this regard, as shown in FIG. 4, when the wafers W and the dummy wafers DW are alternately held, the surface of the wafer W, that is, the element formation surface 200 on which the semiconductor elements are formed faces the back surface of the dummy wafer DW. To do. No semiconductor element is formed on the dummy wafer DW. For this reason, even if scattered copper adheres to the back surface of the dummy wafer DW, there is no influence.

  As described above, in the substrate processing method according to the example, the plurality of wafers W and the plurality of dummy wafers DW are alternately held on the wafer boat 5 having the support 6 having the plurality of grooves 6a. Then, the wafer boat 5 in which the wafers W and the dummy wafers DW are alternately held is carried into the processing container 1 that performs a dry process using an organic compound gas, and a plurality of the wafer boats 5 held in the wafer boat 5 are stored in the processing container 1. For the wafer W, an organic compound gas is used, and a dry process is performed on a thin film containing copper or a copper alloy.

  With such a structure, the possibility of causing deterioration in the operation performance of the transistor can be reduced. In addition, since a plurality of wafers W are processed at a time, even if it is a low-temperature process, it is possible to perform dry processing using an organic compound gas with high throughput.

(Example of semiconductor device manufacture)
Next, an example of a semiconductor device manufacturing method using the substrate processing method according to an example will be described.

  7A to 7F are cross-sectional views showing an example of a semiconductor device manufacturing method that can use the substrate processing method according to the embodiment of the present invention.

  FIG. 7A shows a point in time at which the transistor 201 and the internal wiring 203 containing copper or a copper alloy electrically connected to the source and drain 202 of the transistor 201 are formed on the element formation surface 200 of the wafer W. ing. An example of forming the upper layer internal wiring from this point will be described below as an example of the manufacturing method.

  First, as shown in FIG. 7B, an upper interlayer insulating film 205 is formed on the internal wiring 203 and the interlayer insulating film 204. In this example, since dry cleaning using an organic compound gas that hardly applies thermal stress to the interlayer insulating film is performed at a low temperature, the upper interlayer insulating film 205 can be made of a material that is weak against heat. Therefore, a low-k film having a lower dielectric constant than that of the inorganic silicon oxide film is preferably used for the upper interlayer insulating film 205. For example, the dielectric constant k of the inorganic silicon oxide film deposited using the CVD method with the source gas being TEOS is about 4.2. Therefore, in this specification, the Low-k film is defined as an insulating film having a dielectric constant k of less than 4.2.

As an example of a Low-k film,
1) Siloxane materials 2) Organic materials 3) Porous materials and the like can be mentioned.

As an example of the siloxane-based material,
1) Material containing Si, O, H, for example, HSQ (Hydrogen-Silsesquioxane)
2) Materials containing Si, C, O, and H, for example, MSQ (Methyl-Silsequioxane)
And so on.

As an example of the organic material,
1) Polyarylene ether material 2) Polyarylene hydrocarbon material 3) Parylene material 4) Benzocyclobutene (BCB) material 5) Polytetrafluoroethylene (PTFE) material 6) Fluorinated polyimide material 7) A CF-based material formed using a fluorocarbon gas as a raw material.

As an example of the porous material,
1) Porous MSQ
2) Porous polyarylene hydrocarbon 3) Porous silica and the like.

  Next, as shown in FIG. 7C, a recess 206 having a via hole 206a reaching the internal wiring 203 and a groove 206b having an upper internal wiring pattern is formed in the upper interlayer insulating film 205 by using the dual damascene method. . When the recess 206 is formed, the surface of the internal wiring 203 is exposed at the bottom of the via hole 206a. However, since the internal wiring 203 contains copper or a copper alloy, copper oxide 207 is formed on the surface thereof. In addition, etching residue copper oxide 207a may adhere to the surfaces of the via hole 206a and the groove 206b. The copper oxide 207 or 207a is removed using the dry cleaning apparatus 100 shown in FIG. Further, as shown in FIG. 4, the plurality of wafers W are held in the wafer boat 5 alternately with the dummy wafers DW, and then the plurality of wafers W are loaded into the processing container 1 of the dry cleaning apparatus 100.

  Next, as shown in FIG. 7D, an organic compound gas, for example, formic acid gas, is supplied into the processing container 1, and the temperature of the wafer W is set to, for example, 80 ° C. or more and 200 ° C. or less to the internal wiring 203. Perform dry treatment. By this dry treatment, the copper oxide 207 or 207a is removed.

  When formic acid gas is used, the reaction formula when the copper oxide 207 or 207a is removed is as follows.

Cu ₂ O + 2HCOOH → 2Cu (HCOO) + H ₂ O
Cu (HCOO) is volatile However, since the volatilized Cu (HCOO) is unstable and easily decomposes into Cu, Cu tends to adhere particularly to the back surface of the dummy wafer DW.

2Cu (HCOO) → 2Cu + H 2 + 2CO 2
The organic compound gas is not limited to formic acid gas, and organic compound gas other than formic acid gas can be used.

For example, organic compound gas
An alcohol having a hydroxyl group (—OH) An aldehyde having an aldehyde group (—CHO) A carboxylic acid having a carboxyl group (—COOH) may be selected.

When the organic compound gas is alcohol, this alcohol is
Primary alcohol secondary alcohol polyhydroxy alcohol cyclic alcohol having a plurality of carbon atoms in a part of the ring,
It may be selected from any of aromatic alcohols.

Also, when the organic compound gas is an aldehyde, this aldehyde is
(1) Aldehyde described by the formula R ¹ —CHO (1)
(R ¹ is hydrogen, or a linear or branched C _{1 to} C ₂₀ alkyl group or alkenyl group)
Or alkanediol compound represented by formula (2) OHC-R ² —CHO (2)
(Saturated or unsaturated hydrocarbon ^{R 2} is _C 1 _{-C 20} linear or branched)
Or (2) R ² is not present in the alkane diol compounds described by the formula, it is sufficient chosen from any of those two aldehyde groups are bonded to each other.

When the organic compound gas is a carboxylic acid, the carboxylic acid is
(3) Carboxylic acid R ³ —COOH described by the formula (3)
(R ³ is hydrogen, or a linear or branched C ₁ -C ₂₀ alkyl group or alkenyl group)
You may choose from.

  Next, the wafer W is transferred to a film forming apparatus for forming a barrier film, and as shown in FIG. 7E, a conductive barrier film 208 is formed on the upper interlayer insulating film 205 in which the recesses 206 are formed. An example of the barrier film is a titanium nitride film.

  Next, as shown in FIG. 7F, copper or a copper alloy is embedded in the recess 206 to form an upper layer wiring 209.

  The substrate processing method according to the present invention can be applied to such a semiconductor device manufacturing process.

(Other examples of wafer arrangement)
FIG. 8 is a diagram schematically showing another example of the arrangement of the wafers W on the wafer boat 5 employed in the substrate processing method according to one embodiment of the present invention.

  As shown in FIG. 8, a plurality of wafers W may be held alternately on the front and back by a wafer boat 5 having a plurality of target substrate holders, in this example, a column 6 having a plurality of grooves 6a. good.

  The front and back alternate wafer holding shown in FIG. 8 includes, for example, the substrate processing apparatus shown in FIG. 1 or a transfer mechanism that transfers the wafer W to the wafer boat 5 with a reversing mechanism that reverses the wafer W. Can be realized.

  With such an arrangement of the wafers W, the element formation surfaces 200 of the wafers W face each other. On the element formation surface 200, for example, when removing the copper oxide 207 as shown in FIG. 7D, the removal of the copper oxide proceeds. For this reason, compared with the back surface of the wafer W, copper hardly adheres. In addition, the element formation surface 200 is well cleaned in the cleaning performed before each manufacturing process as compared with the back surface of the wafer W, and the cleanliness is always high. For this reason as well, copper does not adhere to the element forming surface 200 as compared with the back surface of the wafer W, and even if it adheres, it does not easily remain.

  Therefore, even if a plurality of wafers W are held alternately on the front and back of the wafer boat 5, the organic compound gas is used at a low temperature process and with a high throughput while reducing the possibility of causing deterioration in the operation performance of the transistor. A substrate processing method that enables substrate processing can be obtained.

  Moreover, in the other example, compared to the example shown in FIG. 4, since the dummy wafer DW is not used, the throughput can be further increased.

  The present invention has been described according to the embodiment. However, the present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit of the invention. In the embodiment of the present invention, the above-described embodiment is not the only embodiment.

  For example, in the above-described embodiment, the removal of copper oxide from the surface of the internal wiring containing copper or a copper alloy has been described as an example of application to a semiconductor device manufacturing process. However, the present invention is not limited to this manufacturing process. For example, the present invention can also be applied to a case where a copper-containing oxide is removed from a surface of an electrode containing copper or a copper alloy by sublimation into a gas phase. Alternatively, it can also be used when patterning is performed by etching copper or a copper alloy. That is, the present invention can be applied to all dry treatments for thin films containing copper or copper alloys.

  Moreover, although the semiconductor wafer was illustrated as a to-be-processed substrate, the to-be-processed object may be the glass substrate used for manufacture of FPD or a solar cell, and the to-be-processed by which the thin film containing copper or a copper alloy is formed The present invention can be applied to any substrate as long as it is a substrate.

  DESCRIPTION OF SYMBOLS 1 ... Processing container, 2 ... Ceiling board, 3 ... Manifold, 4 ... Sealing member, 5 ... Wafer boat, 6 ... Support | pillar, 6a ... Groove, 7 ... Thermal insulation cylinder, 8 ... Table, 9 ... Cover part, 10 ... Rotating shaft , 11 ... Magnetic fluid seal, 12 ... Seal member, 13 ... Organic compound gas supply mechanism, 14 ... Gas piping, 15 ... Dispersion nozzle, 16 ... Heater, 200 ... Element formation surface, 201 ... Transistor, 202 ... Source, drain, 203 ... Internal wiring, 204 ... Interlayer insulating film, 205 ... Upper interlayer insulating film, 206 ... Recess, 207, 207a ... Copper oxide, 208 ... Barrier film, 209 ... Upper wiring.

Claims (8)

A substrate processing method for a substrate to be processed having a thin film containing copper or a copper alloy,
A step of alternately holding a plurality of substrates to be processed and a plurality of dummy substrates on a substrate substrate to be processed having a plurality of substrate substrates to be processed;
Carrying the substrate substrate boat alternately holding the substrate to be processed and the dummy substrate into a processing container for performing a dry process using an organic compound gas;
A step of performing a chemical dry process on the thin film containing copper or copper alloy, using the organic compound gas, with respect to the plurality of substrates to be processed held in the substrate boat to be processed in the processing container. When,
Equipped with,
The said process is performed in said order, The substrate processing method characterized by the above-mentioned . A substrate processing method for a substrate to be processed having a thin film containing copper or a copper alloy,
A step of holding a plurality of substrates to be processed alternately on a front and back sides of a substrate substrate boat having a plurality of substrate substrates to be processed.
Carrying the substrate boat, which holds the substrate to be processed alternately, into a processing container that performs a dry process using an organic compound gas; and
A step of performing a chemical dry process on the thin film containing copper or copper alloy, using the organic compound gas, with respect to the plurality of substrates to be processed held in the substrate boat to be processed in the processing container. When,
Equipped with,
The said process is performed in said order, The substrate processing method characterized by the above-mentioned . 3. The substrate processing method according to claim 1, wherein the chemical dry process is a process of removing copper oxide from the surface of the thin film containing copper or a copper alloy.   The substrate processing method according to claim 1, wherein the substrate to be processed includes a Low-k film. The organic compound gas is
The substrate processing method according to claim 4, wherein the substrate treatment method is selected from any of an alcohol having a hydroxyl group (—OH), an aldehyde having a aldehyde group (—CHO), and a carboxylic acid having a carboxyl group (—COOH). When the organic compound gas is an alcohol, the alcohol
Primary alcohol secondary alcohol polyhydroxy alcohol cyclic alcohol having a plurality of carbon atoms in a part of the ring,
The substrate processing method according to claim 5, wherein the substrate processing method is selected from any one of aromatic alcohols. When the organic compound gas is an aldehyde, the aldehyde
(1) Aldehyde described by the formula R ¹ —CHO (1)
(R ¹ is hydrogen, or a linear or branched C _{1 to} C ₂₀ alkyl group or alkenyl group)
Or alkanediol compound represented by formula (2) OHC-R ² —CHO (2)
(Saturated or unsaturated hydrocarbon ^{R 2} is _C 1 _{-C 20} linear or branched)
Or (2) R ² is not present in the alkane diol compounds described by the formula, the substrate processing method according to claim 5, characterized in that both the aldehyde groups are selected from any of those bound to each other. When the organic compound gas is a carboxylic acid, the carboxylic acid is
(3) Carboxylic acid R ³ —COOH described by the formula (3)
(R ³ is hydrogen, or a linear or branched C ₁ -C ₂₀ alkyl group or alkenyl group)
The substrate processing method according to claim 5, wherein the substrate processing method is selected from the following.

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