JP5921977B2 - Barrier insulating film formation method - Google Patents

Description

The present invention, the barrier insulating film, in particular, through silicon via (Through Silicon Via: TSV) about the formation how the barrier insulating film for being formed around insulate the TSV and the silicon substrate.

  Conventionally, silicon-based semiconductor devices include various insulating materials such as silicon oxide, which is a constituent material of an interlayer insulating film, and transition metal oxide, which is a constituent material of a capacitor as described in Patent Document 1, for example. Is used.

  In recent years, as one of the technologies for improving the performance of such semiconductor devices, as described in Patent Document 2, for example, a through electrode (Through Silicon Via (TSV)) formed on a silicon substrate is used. Attention has been focused on a three-dimensional mounting technique in which a plurality of semiconductor chips are stacked via a via. FIG. 9 shows a partial cross-sectional structure of a semiconductor device having a TSV.

  The semiconductor device 10 includes a silicon substrate 11 on which elements such as transistors are formed, and various wirings connected to the elements of the silicon substrate 11 on a low dielectric constant insulating film, for example, while being stacked on the upper surface of the silicon substrate 11. The wiring layer 12 is formed. An insulating layer 13 such as silicon oxide is formed so as to cover the upper surface of the wiring layer 12, and an adhesive layer 14 is formed so as to cover the lower surface of the silicon substrate 11.

  Further, the semiconductor device 10 is formed with a through hole H that penetrates the adhesive layer 14, the silicon substrate 11, the wiring layer 12, and the insulating layer 13. In the through hole H, for example, a silicon through electrode 15 formed of a metal such as copper is formed through a barrier insulating film 16. The barrier insulating film 16 suppresses the connection between the silicon through electrode 15 and the wiring of the wiring layer 12 and the movement of the metal element constituting the silicon through electrode 15 to the outside of the through hole H.

  Such a semiconductor device 10 is three-dimensionally mounted with another semiconductor device via the adhesive layer 14. At this time, the silicon through electrode 15 is connected to a semiconductor device on the upper surface side of the semiconductor device 10, a wiring or the like included in the semiconductor device on the lower surface side of the semiconductor device 10.

JP 2008-311663 A JP 2010-87233 A

  Incidentally, a barrier insulating film 16 for insulating the silicon through electrode 15 and the silicon substrate 11 is required around the silicon through electrode 15. The silicon oxide, transition metal oxide, and the like as described above can be used as a material for forming the barrier insulating film 16 for the silicon through electrode 15.

Here, the following characteristics (a) and (b) are required for the barrier insulating film 16 for the through silicon via 15.
(A) Dielectric constant for suppressing signal delay in the silicon through electrode 15 (b) Insulation between the silicon through electrode 15 and the silicon substrate 11 According to the silicon oxide film used for the interlayer insulating film described above, Although the above (a) can be satisfied, since the film density is lower than that of a silicon oxide film formed by a thermal CVD method and contains many impurities, it is extremely difficult to satisfy the above (b). It is. On the other hand, according to the transition metal oxide film used for a capacitor, although the above (b) can be satisfied, it is extremely difficult to satisfy the above (a).

Therefore, there is a demand for a film having more appropriate properties as the barrier insulating film 16 for the through silicon via 15.
The present invention has been made in view of the above circumstances, and its object is a barrier insulating film formed how capable of enhancing the insulation between the through silicon via a silicon substrate while suppressing the signal delay in the through silicon via Is to provide.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a barrier insulating film forming method for forming a barrier insulating film on an inner surface of a through-electrode hole of a silicon substrate, and comprises activated nitrogen and Zr (BH ₄ ) ₄ . Supplying the silicon substrate and nitriding the Zr (BH ₄ ) ₄ with nitrogen to cover the inner surface of the hole with a ZrBN film, supplying oxygen radicals as activated oxygen to the ZrBN film The present invention includes an oxidation step of forming a ZrBON film on the inner surface of the hole by oxidizing the ZrBN film.

A ZrBN film obtained by nitriding Zr (BH ₄ ) ₄ has been intensively studied as a barrier film for metal wiring such as copper. The inventors of the present application have found that the ZrBON film obtained by oxidation of the ZrBN film has the following characteristics in the course of studying the barrier property and step coverage of the ZrBN film.
The ZrBON film exhibits an insulating property substantially equal to that of a silicon oxide film formed by a thermal CVD method while maintaining the barrier property.
The ZrBON film has the same dielectric constant as that of a silicon-based oxide although it is an oxide of Zr, which is a transition metal.

  According to the first aspect of the present invention, after the inner side surface of the through electrode hole is covered with the ZrBN film, the inner side surface of the hole is covered with the ZrBON film by oxidation of the ZrBN film. . Therefore, while providing the barrier insulating film with the same step coverage as the ZrBN film, the barrier insulation has the same dielectric constant as the silicon-based insulating film and the same insulating property as the silicon oxide film formed by thermal CVD. It can be applied to a ZrBON film as a film.

Further, the oxidation of the ZrBN film itself can be performed by supplying oxygen ions, which are one of activated oxygen, to the ZrBN film. However, when oxygen ions are used as the activated oxygen, the ZrBN film is easily damaged by the energy when the oxygen ions are incident on the ZrBN film.

In this regard, according to the first aspect of the present invention, since oxygen radicals are used as the activated oxygen, it is possible to oxidize the ZrBN film with sufficient insulation while suppressing damage as described above. it can.

The gist of the invention described in claim 2 is that the set of the coating step and the oxidation step is repeated a plurality of times.
According to the above method, when forming a ZrBON film having the same film thickness, the entire film is more reliably oxidized than forming the ZrBON film by performing the coating step and the oxidation step only once. A ZrBON film thus formed can be formed.

According to a third aspect of the invention, in the coating step, the gist Rukoto forming forms said ZrBN film by supplying nitrogen radicals, hydrogen radicals, and Zr (BH _{4) 4} in the substrate.

When the hydrogen radical is supplied together with the nitrogen radical and Zr (BH ₄ ) ₄ in forming the ZrBN film, the terminal portion of the ZrBN particle nitrided by the nitrogen radical is terminated (terminated) by the hydrogen radical.

Therefore, as in the invention described in claim 3 above, by supplying hydrogen radicals to the substrate in addition to nitrogen radicals and Zr (BH ₄ ) ₄ in the coating step, a terminator effect due to hydrogen radicals is exhibited. , The size of the ZrBN particles can be reduced. As a result, the step coverage of the ZrBON film can be further enhanced, and the generation of particles in the barrier insulating film forming process can be suppressed.

According to a fourth aspect of the invention, in the coating step, to generate a nitrogen radical to excite the N ₂ gas to generate hydrogen radicals by exciting a H ₂ gas, with N ₂ gas and H ₂ gas The gist is that the partial pressure ratio (P _N2 / P _H2 ) is 3 <P _N2 / P _H2 <5.

  When the ZrBN film is formed while adding hydrogen radicals in the coating step, the step coverage of the ZrBN film is improved, but the deposition rate is lower than when the ZrBN film is formed without adding hydrogen radicals.

In this regard, if the partial pressure ratio between the nitrogen gas and the hydrogen gas is within the above range as in the invention described in claim 4 , the step coverage of the ZrBN film can be improved while suppressing a decrease in the film formation rate. it can.

Sectional view showing the sectional structure of barrier-insulating film forming apparatus. The figure which shows schematic structure of the film-forming chamber which the barrier insulation film forming apparatus has. The flowchart which shows the process sequence of the barrier insulating film formation method. 5 is a timing chart showing how power is supplied from (a) Zr (BH ₄ ) ₄ gas, (b) N ₂ gas, (c) H ₂ gas, (d) O ₂ gas, and (e) a microwave power source. The graph which shows the relationship between the electric field applied to the ZrBON film | membrane, and the current density at that time. (A) (b) (c ) (d) H 2 SEM images of cross-sectional structure is captured between the through-hole ZrBN membrane and the ZrBN film formed without adding gas is formed. (A) (b) (c ) (d) H 2 SEM images of cross-sectional structure is captured between the through-hole gas ZrBN membrane and the ZrBN film formed by adding is formed. Graph showing the _P N2 _{/ P H2} at ZrBN film, the relationship between the coverage of ZrBN film in each part of the through hole. The fragmentary sectional view which shows the partial cross section structure of the semiconductor device which has a silicon penetration electrode.

An embodiment of the barrier insulating film formed how the present invention will be described with reference to FIGS. First, a barrier insulating film forming apparatus will be described with reference to FIGS. In addition, the substrate which is the processing target of the barrier insulating film forming method and the barrier insulating film forming apparatus of the present embodiment is a structure in which the barrier insulating film 16 and the through silicon via 15 are not formed in the semiconductor device 10. It is.

  FIG. 1 shows a schematic configuration of a barrier insulating film forming apparatus embodied as a film forming apparatus. The film deposition apparatus 20 includes a load lock chamber 21, a core chamber 22 coupled to the load lock chamber 21, two deposition chambers 23 coupled to the core chamber 22, and two coupled to the core chamber 22. And an oxidation chamber 24. The chambers 23 and 24 connected to the core chamber 22 and the load lock chamber 21 form one vacuum system by opening the gate valve provided between the core chamber 22 and these chambers. Can do. Hereinafter, the function of each chamber will be described on the assumption that the oxidation process in the oxidation chamber 24 is performed after the film formation process in the film formation chamber 23.

  The load lock chamber 21 is a vacuum chamber that accommodates a plurality of substrates S. When the film forming process for the substrate S is started, the substrate S is carried into the film forming apparatus 20 through the load lock chamber 21. When the oxidation process for the substrate S is completed, the substrate S is carried outside the film forming apparatus 20 via the load lock chamber 21.

  The core chamber 22 is a vacuum chamber in which a transfer robot 22a that transfers the substrate S is mounted. When the film forming process for the substrate S is started, the substrate S in the load lock chamber 21 is carried to the film forming chamber 23 via the core chamber 22 by the transfer robot 22a. When the oxidation process for the substrate S is completed, the substrate S in the oxidation chamber 24 is carried to the load lock chamber 21 via the core chamber 22 by the transfer robot 22a.

  The film formation chamber 23 is a vacuum chamber for forming a zirconium boronitride (ZrBN) film on the substrate S using a CVD method. FIG. 2 shows a schematic configuration of the film forming chamber 23. The film forming chamber 23 includes a chamber main body 31 having an opening in the upper portion, and a chamber lid 32 disposed on the upper portion of the chamber main body 31 so as to close the opening.

  A substrate stage 33 on which the substrate S is placed is disposed in a film forming chamber 31S, which is an internal space formed by the chamber body 31 and the chamber lid 32. The resistance heater 33 </ b> H provided in the substrate stage 33 raises the temperature of the substrate S to a predetermined temperature of, for example, 150 ° C. to 240 ° C. when the substrate S is placed on the substrate stage 33. By placing the substrate S on the substrate stage 33, the position in the film forming chamber 31S is determined, and the temperature is maintained at a predetermined temperature during the film forming process. Below the substrate stage 33 is connected an elevating mechanism 34 that moves the substrate stage 33 in the vertical direction when the substrate S is carried in and out.

  An exhaust pump 35 that exhausts the inside of the film forming chamber 31 </ b> S is connected to a side portion of the chamber body 31 through an exhaust port P <b> 1. The exhaust pump 35 is configured by various pumps such as a turbo molecular pump and a dry pump. When performing the film forming process in the film forming chamber 23, the pressure in the film forming chamber 31S is set to 1 Pa to 1000 Pa, for example. The pressure is reduced to a predetermined pressure.

A shower plate 36 having a plurality of first supply holes H1 and a plurality of second supply holes H2 is attached to the chamber body 32 on the chamber body 31 side.
The first supply holes H1 supply zirconium tetraborohydride (Zr (BH ₄ ) ₄ ), which is a material for forming the ZrBN film, to the film formation chamber 31S. More specifically, Zr (BH ₄ ) ₄ entered the first supply hole H1 through a gas passage GP1 formed inside the chamber lid 32 and a source gas port P2 penetrating the chamber lid 32. A raw material tank TK is connected. A mass flow controller MFC1 for supplying argon (Ar) as a carrier gas to the raw material tank TK is connected to the raw material tank TK. The raw material tank TK derives Zr (BH ₄ ) ₄ and the carrier gas from the first through the raw material gas port P2 together with the carrier gas by bubbling Zr (BH ₄ ) ₄ bubbled by the carrier gas from the mass flow controller MFC1. The film is supplied from the supply hole H1 to the film forming chamber 31S.

On the other hand, the second supply hole H2 supplies excited nitrogen and excited hydrogen to the film forming chamber 31S. More specifically, nitrogen (N ₂ ) gas is supplied to the second supply hole H 2 via a gas passage GP 2 formed inside the chamber lid 32 and an excitation gas port P 3 penetrating the chamber lid 32. A mass flow controller MFC2, a mass flow controller MFC3 that supplies hydrogen (H ₂ ) gas, and a mass flow controller MFC4 that supplies Ar gas are connected. These mass flow controllers MFC2, MFC3, and MFC4 lead each gas to the excitation gas port P3 while metering each gas to a predetermined flow rate.

  Inside the gas passage GP2, and between the excitation gas port P3 and the second supply hole H2, an irradiation tube 37 having heat resistance formed of quartz or alumina is disposed. A microwave source 38 driven by a microwave power source FG is disposed outside the irradiation tube 37 and the chamber lid 32. Further, a waveguide 39 having a gap is provided between the microwave source 38 and the irradiation tube 37 while being connected to the microwave source 38. The microwave source 38 is a magnetron that oscillates a microwave of 2.45 GHz, for example, and outputs a microwave in a predetermined output range, for example, a range of 0.01 kW to 3.0 kW by driving power from the microwave power source FG. . The waveguide 39 guides the inside of the irradiation tube 37 by propagating the microwave oscillated by the microwave source 38 to the inside. The waveguide 39 excites the gas by irradiating the gas passing through the irradiation tube 37 with the microwave when the microwave source 38 oscillates the microwave. The film forming chamber 23 is configured such that radicals generated by excitation of various gases occupy most of the particles supplied into the film forming chamber 31S.

  In the film forming chamber 23, the mass flow controller MFC2, the microwave power source FG, the irradiation tube 37, the microwave source 38, the waveguide 39, the chamber lid 32, and the shower plate 36 constitute a nitrogen supply unit. In addition, the mass flow controller MFC1, the raw material tank TK, the chamber lid 32, and the shower plate 36 constitute a raw material supply unit.

  The oxidation chamber 24 is a vacuum chamber that oxidizes the substrate S on which the ZrBN film is formed. The oxidation chamber 24 has a configuration in which the source gas port P2, the gas passage GP1, and the first supply hole H1 are omitted from the film formation chamber 23 shown in FIG. 2, and a mass flow controller for supplying oxygen gas is provided. The configuration is connected to the excitation gas port P3. More specifically, the oxidation chamber 24 forms a ZrBON film from the ZrBN film by supplying oxygen excited by microwaves from the oxygen supply unit to the surface of the substrate S. In the film forming apparatus 20 of this embodiment, the film forming chamber 23 and the oxidation chamber 24 are provided separately. However, as a single vacuum chamber capable of forming a ZrBN film on the substrate S and oxidizing the ZrBN film by connecting a mass flow controller for supplying oxygen gas to the excitation gas port P3 of the film forming chamber 23. Also good.

  Next, a barrier insulating film forming method will be described with reference to FIGS. FIG. 3 is a flowchart showing a processing procedure of the barrier insulating film forming method. When forming the barrier insulating film, a coating process is performed in the film forming chamber 23 to cover the surface of the substrate S by forming a ZrBN film on the substrate S (step S1).

At this time, N ₂ gas from the mass flow controller MFC2 is supplied into the film forming chamber 31S while being excited in the irradiation tube 37. In addition, in the present embodiment, H ₂ gas from the mass flow controller MFC3 is also supplied into the film forming chamber 31S while being excited in the irradiation tube 37. Also, Zr (BH ₄ ) ₄ gas, which is a mixture of Ar gas from the mass flow controller MFC1 and Zr (BH ₄ ) ₄ in the raw material tank TK, is supplied to the film forming chamber 31S.

As described above, in the coating step, nitrogen radicals are used as excited nitrogen that nitrides Zr (BH ₄ ) ₄ . Therefore, compared to the case of using nitrogen ions that are one of the excited nitrogens, the damage to the already formed ZrBN film by the excited nitrogen reaching the surface of the substrate S can be reduced.

When a ZrBN film is formed by reacting Zr (BH ₄ ) ₄ with excited nitrogen (nitrogen radical), if excited hydrogen (hydrogen radical) is present in the atmosphere in which the formation reaction takes place, At least a part of the unbonded hand is terminated with hydrogen. Therefore, since the ZrBN particle size is difficult to increase, the ZrBN film is easily formed on the entire inner surface of the through hole H of the substrate S. In other words, the step coverage of the formed ZrBN film is improved. In addition, since ZrBN is unlikely to deposit on the inner wall of the chamber body 31, the opening surface of the shower plate 36, etc., particles are less likely to be generated in the film forming chamber 31S. Then, Zr (BH ₄ ) ₄ gas reacts with nitrogen radicals and hydrogen radicals, whereby a ZrBN film is formed on the upper surface of the substrate S and the inner surface of the through hole H formed in the substrate S. In the covering step, the pressure in the film forming chamber 31S may be adjusted by supplying Ar gas from the mass flow controller MFC4 in addition to the N ₂ gas and H ₂ gas.

  Next, after the substrate S on which the ZrBN film is formed is transferred from the film formation chamber 23 to the oxidation chamber 24, an oxidation process is performed in which the surface of the substrate S is oxidized to form a ZrBON film from the ZrBN film ( Step S2).

  At this time, oxygen (oxygen radicals) excited in the irradiation tube is supplied into the film forming chamber, whereby the ZrBN film covering the substrate S is oxidized from the surface. In the present embodiment, the ZrBN film is oxidized entirely in the surface direction and the thickness direction of the ZrBN film formed on the surface of the substrate S and the inner side surface of the through hole H.

Such oxidation of the ZrBN film itself is also possible by supplying oxygen ions to the surface of the ZrBN film. However, when oxygen ions are used, the ZrBN film is easily damaged by energy when the oxygen ions are incident on the ZrBN film. In this regard, according to the present embodiment, since the ZrBN film is oxidized using oxygen radicals having energy lower than that of oxygen ions, the ZrBON film can be oxidized while suppressing damage to the ZrBN film. it can. In addition, when the ZrBON film is formed, the entire surface direction and thickness direction of the ZrBN film are oxidized. For this reason, since insulation is expressed over the entire barrier insulating film 16 formed on the inner surface of the through hole H, the silicon through electrode 15 and conductive materials other than wiring connected to the silicon through electrode 15 and Is more reliably insulated. Note that also in the oxidation step, the pressure in the deposition chamber may be adjusted by supplying Ar gas in addition to O ₂ gas.

  Then, the ZrBN film is formed and oxidized repeatedly until the ZrBON film having a predetermined film thickness is formed by performing the combination of the coating process and the oxidation process n times, for example, 5 times (step). S3). Thus, in the present embodiment, the ZrBON film is formed by repeating the combination of the coating process and the oxidation process a plurality of times. Therefore, when forming a ZrBON film having the same film thickness, a ZrBON film in which the entire film is oxidized more reliably than forming the ZrBON film by performing the coating step and the oxidation step only once. Can be formed.

Next, the covering step and the oxidizing step will be described in detail with reference to FIG. FIG. 4 shows the on state of the mass flow controller that supplies (a) Zr (BN ₄ ) ₄ gas, (b) N ₂ gas, (c) H ₂ gas, and (d) O ₂ gas when the barrier insulating film is formed. By showing the mode of (ON) and off (OFF), the mode of supplying various gases to each port is shown. In addition, (e) the mode of supplying microwaves from the microwave source to the irradiation tube is shown by showing the mode of turning on (ON) and turning off (OFF) the microwave power source.

First, supply of Zr (BH ₄ ) ₄ gas, N ₂ gas, and H ₂ gas is started in a state where the substrate S is loaded into the film forming chamber 23 (timing t1). The supply flow rates of Ar gas, N ₂ gas, and H ₂ gas, which are carrier gases of Zr (BH ₄ ) ₄ , are, for example, 100 sccm, 400 sccm, and 100 sccm, respectively. Note that the supply flow rate of Ar gas as a carrier gas is set in a range in which the supply amount of Zr (BH ₄ ) ₄ increases linearly as the supply flow rate of Ar gas is increased.

As described above, the step coverage of the ZrBN film is enhanced by forming the ZrBN film while adding hydrogen radicals in the coating step. However, since the ZrBN particle size is not easily increased by hydrogen radicals, the deposition rate is lower than when a ZrBN film is formed without adding hydrogen radicals. Therefore, as in the present embodiment, P _N2 / P _H2 , which is the partial pressure ratio between N ₂ gas and H ₂ gas, is “4”, that is, H ₂ gas among the mixed gas of N ₂ gas and H ₂ gas. If the proportion occupied by 20% is 20%, the step coverage of the ZrBN film can be improved while suppressing a decrease in the deposition rate. In addition, the inventor of the present application can suppress the rapid decrease in the film formation rate and obtain the above-described effect if the partial pressure ratio between the N ₂ gas and the H ₂ gas is in the range of 3 <P _N2 / P _H2 <5. It is confirmed that

Thereafter, the microwave power source FG is turned on, whereby the microwave is supplied from the microwave power source FG to the irradiation tube 37 (timing t2). The amount of microwave power is set to 40 W, for example. Thus, when supply of Zr (BH ₄ ) ₄ , nitrogen radicals, and hydrogen radicals to the surface of the substrate S is started, the Zr (BH ₄ ) ₄ is nitrided by the nitrogen radicals, so that the ZrBN film becomes the substrate S And the inner surface of the through hole H of the substrate S. Note that the supply of microwaves is started after a predetermined period from the start of the supply of the various gases. Therefore, it is possible to stably excite N ₂ gas and H ₂ gas rather than simultaneously starting supply of various gases and supply of microwaves. Incidentally, the period from the timing t1 to the timing t2 is a time until the flow rate of the gas supplied to each port becomes constant, for example, a time until the gas from the mass flow controller reaches the port. .

  When the microwave supply is performed for a predetermined period, for example, 1 minute, the supply of the various gases and the supply of the microwave are stopped (timing t3). In this embodiment, the period during which the microwave is supplied is used as the coating process. Therefore, the period from the timing t2 to the timing t3 corresponds to the coating process.

When the coating process is completed, the substrate S is transferred from the film formation chamber 23 to the oxidation chamber 24, and then the supply of O ₂ gas is started (timing t4). The supply flow rate of the O ₂ gas is, for example, 100 sccm. Note that the time from the timing t3 to the timing t4 is set to a time until the loading of the substrate S into the oxidation chamber 24 is completed, for example.

Thereafter, the microwave power source is turned on, whereby the microwave is supplied from the microwave source to the irradiation tube (timing t5). The amount of microwave power is set to 100 W, for example. Thereby, the supply of oxygen radicals to the surface of the substrate S is started, and thus the oxidation of the ZrBN film is started. Note that the microwave supply is started after a predetermined period from the start of the O ₂ gas supply. Therefore, the O ₂ gas can be excited stably as at the start of the coating step. Incidentally, the period from the timing t4 to the timing t5 is set to the time until the O ₂ gas from the mass flow controller reaches the port, similarly to the period from the timing t1 to the timing t2.

Then, when the supply of microwaves is performed for a predetermined period, for example, 1 minute, the supply of O ₂ gas and the supply of microwaves are stopped (timing t6). In this embodiment, the period during which microwaves are supplied is used as the oxidation process. Therefore, the period from the timing t5 to the timing t6 corresponds to the oxidation process.

When the oxidation process is completed, the substrate S is transferred from the oxidation chamber 24 to the film forming chamber 23, and then the coating process is performed. When the combination of the covering step and the oxidizing step is repeated a predetermined number of times, for example, five times, the substrate S is unloaded from the film forming apparatus 20 and the formation of the barrier insulating film 16 with respect to the through hole H of the substrate S is completed. Note that timing t7 in FIG. 4 is the supply start timing of O ₂ gas in the fifth oxidation step, and timing t8 is the supply start timing of microwave. Timing t9 is the supply stop timing of O ₂ gas and microwave.

[Example]
[Dielectric constant and leakage current value of ZrBON film]
A ZrBON film having a thickness of 100 nm was formed by performing a coating process for forming a ZrBN film and an oxidation process for oxidizing the ZrBN film on a silicon substrate having a diameter of 200 mm under the following conditions.

[Example 1]
<Coating process>
・ Carrier gas (Ar gas) flow rate 100sccm
・ N ₂ gas flow rate 400sccm
・ H ₂ gas flow rate 100sccm
・ Pressure inside the deposition chamber 410Pa
・ Microwave power 100W
・ Substrate temperature 210 ℃
<Oxidation process>
・ O ₂ gas flow rate 100sccm
・ The pressure in the deposition chamber is 70 Pa.
・ Microwave power 100W
・ Substrate temperature 210 ℃
First, the dielectric constant of the ZrBON film was calculated by the following method. That is, a CV characteristic was measured by superimposing a 1 MHz high frequency on a DC bias using a mercury probe, and then the dielectric constant was calculated from the measurement result of the CV characteristic.

Along with the measurement result of the dielectric constant of the ZrBON film, silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), zirconium oxide (ZrO ₂ ), which is an oxide of a transition metal, hafnium oxide ( The dielectric constants of HfO ₂ ) and tantalum oxide (Ta ₂ O ₅ ) are shown in Table 1. In addition, as the value of ZrBON, the minimum value and the maximum value among the results of measuring the dielectric constant of five samples are described.

As shown in Table 1, it was confirmed that the dielectric constant of the ZrBON film formed by oxidizing the ZrBN film was extremely lower than the oxides of other transition metals including the oxide of Zr. In addition, it was confirmed that the dielectric constant was the same as that of the SiO ₂ film, which is a low dielectric constant film in which signal delay hardly occurs. Therefore, a ZrBON film formed through a coating process for forming a ZrBN film and an oxidation process for oxidizing the ZrBN film formed in the coating process was used as a barrier insulating film for a through silicon via (TSV). In this case, the signal delay in the TSV can be suppressed as compared with the oxide film of other transition metals.

Next, the current density J (A / cm ² ) as a leakage current of the test ZrBON film was measured by the following method. That is, the silicon substrate on which the ZrBON film was formed was grounded and a positive voltage was applied to the mercury probe on the ZrBON film to measure the current density with respect to the electric field E (MV / cm) applied to the ZrBON film. . The value of the leakage current measured by such a method is shown in FIG.

As shown in FIG. 5, the ZrBON film has a current density value that does not exceed 1 × 10 ⁻⁸ A / cm ² , which is considered to be practically preferable, even when an electric field of 3 MV / cm is applied. It was recognized that there was. In the case of these silicon-based insulating films such as a silicon oxide film and a silicon nitride film formed by the plasma CVD method, when an electric field of 1 MV / cm is applied in the measurement method, 1 × 10 ⁻⁸ A / It was a value exceeding cm ² . Therefore, by using the ZrBON film formed by the above-described method as the barrier insulating film for the TSV, it is possible to insulate the silicon substrate from the TSV rather than using the silicon-based insulating film formed by the plasma CVD method. It can be said that it can improve the nature.

[Barrier properties of ZrBON film]
A test wafer (No. 1) was obtained by laminating a ZrBON film by 20 nm under the above conditions on a silicon substrate having a copper film having a thickness of 100 nm. Then, the test wafer (No. 1) was annealed in an atmosphere at 500 ° C. for 1 hour, and then elemental analysis in the film thickness direction by SIMS measurement was performed on the ZrBON film.

  A test wafer (NO. 2) was obtained by laminating a ZrBON film by 20 nm on a silicon substrate having an aluminum film having a thickness of 100 nm under the above conditions. And after performing the annealing process similar to the said test wafer (No. 1) with respect to the test wafer (No. 2), the elemental analysis of the film thickness direction by SIMS measurement was performed with respect to the ZrBON film | membrane.

  As a result of SIMS measurement, the presence of copper was not observed in the ZrBON film of the test wafer (No. 1). In addition, the presence of aluminum was not observed in the ZrBON film of the test wafer (No. 2). Therefore, it can be said that the ZrBON film formed by the above film formation method has a function of suppressing diffusion of copper and aluminum, that is, a barrier property.

[Step coverage of ZrBN film]
In order to evaluate the effect of H ₂ gas on the burying property of the ZrBN film formed in the coating step with respect to the through hole, in other words, the step coverage, the diameter was changed under the conditions of Example 2 and Example 3 below. A ZrBN film was formed on a silicon substrate having a diameter of 200 mm in which a plurality of through holes having a diameter of 20 μm and a depth of 100 μm were formed. In the Example 2 and Example 3, since only the supply flow rate of N ₂ gas and H ₂ gas are different, for example 3 describes only the supply flow rate of N ₂ gas and H ₂ gas.

[Example 2]
・ Carrier gas (Ar gas) flow rate 100sccm
・ N ₂ gas flow rate 500sccm
・ H ₂ gas flow rate 0sccm
・ Pressure inside the deposition chamber 410Pa
・ Microwave power 100W
・ Substrate temperature 210 ℃
-Film formation time 300 seconds [Example 3]
・ N ₂ gas supply flow rate 400sccm
・ H ₂ gas supply flow rate 100 sccm
As described above, in Example 2, whereas the addition ratio of the H ₂ gas occupying the mixed gas of N ₂ gas and H ₂ gas was set to 0%, in Example 3, the addition ratio of the H ₂ gas 20 %. 6A to 6D show SEM images of the cross section of the ZrBN film formed in Example 2, and FIG. 7A shows the SEM image of the cross section of the ZrBN film formed in Example 3. Shown in (d). In each figure, (a) is an SEM image showing the entire through-hole and the ZrBN film formed on the inner surface thereof, and (b) is a through-hole on the surface side of the silicon substrate and ZrBN formed on the inner surface thereof. The SEM image of the film, (c) is the SEM image of the ZrBN film near the center in the depth direction of the through hole, and (d) is the SEM image of the ZrBN film on the bottom side of the through hole.

  In Example 2, as shown in FIG. 6B, when the thickness of the ZrBN film formed on the surface of the silicon substrate is the surface thickness T1, the surface thickness T1 is 30.3 nm. Further, as shown in FIG. 6C, when the thickness of the ZrBN film formed on the side surface of the through hole is the side surface thickness T2 near the center in the depth direction of the through hole, the side surface thickness T2 was 11.9 nm. As shown in FIG. 6D, when the thickness of the ZrBN film formed on the bottom surface of the through hole is defined as the bottom surface thickness T3, the bottom surface thickness T3 is 11.9 nm.

  On the other hand, in Example 3, as shown in FIG. 7B, the surface thickness T1 of the ZrBN film was 44.3 nm. Further, as shown in FIG. 7C, the side surface thickness T2 of the ZrBN film was 44.3 nm. As shown in FIG. 7D, the bottom thickness T3 of the ZrBN film was 52.3 nm.

FIG. 8 shows the ratio of the side surface thickness T2 to the surface thickness T1 when the ratio between the N ₂ gas flow rate and the H ₂ gas flow rate is changed and the other conditions are the same as those in the second and third embodiments. It is a graph which shows a certain side coverage and the bottom face coverage which is ratio of bottom face thickness T3 with respect to surface thickness T1. In FIG. 8, the side surface coverage is indicated by a solid line and the bottom surface coverage is indicated by a broken line. The side coverage in Example 2 was 46.5%, and the bottom coverage was 37.6%. On the other hand, the side coverage in Example 3 was 100% and the bottom coverage was 118%. FIG. 8 is a graph showing the deposition rate when the ratio between the N ₂ gas flow rate and the H ₂ gas flow rate is changed and the other conditions are the same as those in the second and third embodiments.

As shown in FIG. 8, it was confirmed that the coverage of the ZrBN film on the side surface and the bottom surface of the through hole can be increased by increasing the H ₂ gas addition ratio in the coating step. Therefore, it can be said that the step coverage of the ZrBN film can be enhanced by increasing the H ₂ gas addition ratio in the coating step. In the oxidation process following the coating process, even if the entire surface direction and thickness direction of the ZrBN film are oxidized to form a ZrBON film, the coverage of the film in the through hole H when the ZrBN film is formed is generally maintained. Be drunk. Therefore, even if the coating step and the oxidation step are repeated a plurality of times, if the conditions during the coating step are the same, the coverage rate when the coating step is performed only once is generally maintained. That is, it can be said that the step coverage of the ZrBON film can be enhanced by increasing the H ₂ gas addition ratio in the coating step. In addition, it was confirmed that when the partial pressure ratio between the N ₂ gas and the H ₂ gas is in the range of 3 <P _N2 / P _H2 <5, a rapid decrease in the film formation rate can be suppressed.

According to the embodiment, the effects listed below can be obtained.
(1) After covering the inner surface of the through-hole H for the silicon through-electrode 15 of the substrate S with a ZrBN film, the inner surface of the through-hole H was covered with the ZrBON film by oxidation of the ZrBN film. Therefore, the ZrBN film as the barrier insulating film 16 has the same dielectric constant as the plasma oxide film and the same insulating property as the thermal oxide film while providing the same step coverage to the barrier insulating film 16 as the ZrBN film. Can be given.

  (2) An oxygen radical is used as the activated oxygen that oxidizes the ZrBN film. Therefore, it is possible to oxidize the ZrBN film with sufficient insulation while suppressing damage to the ZrBN film, rather than supplying oxygen ions, which are one of activated oxygen, to the ZrBN film and oxidizing it. .

  (3) The ZrBON film as the barrier insulating film 16 is formed by repeating the combination of the coating process and the oxidation process a plurality of times. Therefore, if the ZrBON film having the same film thickness is formed, the entire film is more reliably oxidized than the ZrBON film formed by performing the coating process and the oxidation process only once. A ZrBON film can be formed.

(4) In the coating step, hydrogen radicals are supplied to the substrate S in addition to nitrogen radicals and Zr (BH ₄ ) ₄ . Therefore, the size of the ZrBN particles can be reduced by the amount that the termination effect of the ZrBN particles by the hydrogen radicals is expressed. As a result, the step coverage of the ZrBON film can be further improved, and the generation of particles in the step of forming the barrier insulating film 16 can be suppressed.

(5) In the coating step, P _N2 / P _H2 , which is a partial pressure ratio between nitrogen gas and hydrogen gas, was set to 3 <P _N2 / P _H2 <5. Therefore, the step coverage of the ZrBN film can be enhanced while suppressing a decrease in the deposition rate when forming the ZrBN film.

In addition, the said embodiment can also be suitably changed and implemented as follows.
The substrate S to be processed by the film forming apparatus 20 is configured to include the silicon substrate 11, the wiring layer 12, the insulating layer 13, and the adhesive layer 14. However, the present invention is not limited to this, and any configuration that includes at least the silicon substrate 11 in which the through holes H are formed may be used.

The carrier gas for Zr (BH ₄ ) ₄ is not limited to Ar gas, and other inert gases such as He, Ne, Kr, Xe gas, etc. may be used.
In the coating step, N ₂ gas was used as a source of activated nitrogen, and H ₂ gas was used as a source of activated hydrogen. For example, ammonia (NH ₃ ) gas which is a generation source of activated nitrogen and activated hydrogen may be used. Further, the combined use of N ₂ gas and NH ₃ gas or the combined use of H ₂ gas and NH ₃ gas is also possible.

In the oxidation process, O ₂ gas was used as a source of activated oxygen. In addition to this, in the oxidation step, in addition to O ₂ gas, H ₂ gas may be used, or H ₂ gas and dinitrogen monoxide (N ₂ O) gas may be used. Accordingly, the composition of the ZrBON film can be adjusted by hydrogen or nitrogen contained in the oxidizing atmosphere while forming the ZrBON film by oxidizing the ZrBN film. Therefore, the composition of the ZrBON film can be optimized in order to develop the characteristics as the barrier insulating film 16.

· Zr _{(BH 4)} 4 gas, and be started simultaneously with _{H 2} gas, and the timing t1 the supply of _{N 2} gas. The timing for starting the supply of these gases is not limited to this, and can be arbitrarily changed, such as for each.

・ Supplying microwaves after supplying various gases. Not limited to this, the supply of various gases and the supply of microwaves may be performed simultaneously.
-In the coating process and the oxidation process, the supply of various gases and the supply of microwaves were stopped simultaneously. Not limited to this, the supply of various gases may be stopped after the supply of microwaves is stopped.

As described above, the film forming apparatus 20 may be embodied as an apparatus capable of performing the coating process and the oxidation process in a single chamber. In this case, Zr (BH ₄ ) ₄ gas and N ₂ gas used in the coating process are provided between timing t3, which is the timing of ending the coating process, and timing t4, which is the supply timing of the oxygen gas used in the oxidation process. And the time until the H ₂ gas is exhausted from the chamber. Further, the O ₂ gas used in the oxidation process is also in the chamber between the timing t6 that is the end timing of the oxidation process and the supply start timing of Zr (BH ₄ ) ₄ gas or the like that is performed following the oxidation process. The time from exhaust to exhaust is sufficient.

Process conditions such as the substrate temperature, the pressure in the deposition chamber, and the microwave power in the coating process and the oxidation process can be arbitrarily changed within a range in which the ZrBN film can be formed and oxidized.
· The P _{N2 /} P _H2 is the partial pressure ratio of nitrogen gas and hydrogen gas in the coating process, may not in the above range 3-5, may be a partial pressure ratio which can form a ZrBN film.

In the coating step, the ZrBN film may be formed while supplying hydrogen ions instead of hydrogen radicals.
In the coating step, the ZrBN film is formed while supplying hydrogen radicals, but the ZrBN film may be formed without supplying hydrogen radicals.

In the coating step, nitrogen radicals were used as activated nitrogen for nitriding Zr (BH ₄ ) ₄ . Not limited to this, if the impact of ions in the coating process does not affect the electrical characteristics of the elements formed on the silicon substrate or the ZrBON film, nitrogen ions may be used as the activated nitrogen. .

As described above, if Zr (BH ₄ ) ₄ is nitrided by nitrogen ions in the coating process, the film forming chamber 23 includes a microwave power source FG, an irradiation tube 37, a microwave source 38, and a waveguide. Instead of 39, a high-frequency power source may be provided.

-The number of times of repeating the combination of the coating process and the oxidation process was set to 5 times. Not limited to this, the number of times of repeating the combination of the coating step and the oxidation step can be any number of one or more. That is, the number of times to repeat the above set may be determined according to the target film thickness of the barrier insulating film 16 formed in the through hole H, the thickness of the ZrBN film that can be formed per coating process, and the like.
In the above oxidation step, the ZrBN film is oxidized in the entire surface direction and thickness direction of the ZrBN film formed on the surface of the substrate S and the inner surface of the through hole H. You may carry out on the conditions on which at least one part of the surface direction of a film | membrane and at least one part of the thickness direction are oxidized. Even if the ZrBN film is oxidized under such conditions, since the ZrBN film is oxidized, a film having an insulating property can be obtained.

  In the method for forming the barrier insulating film, the barrier insulating film is formed by performing the covering process in the film forming chamber 23 of the film forming apparatus 20 and then performing the oxidizing process in the oxidation chamber 24 of the film forming apparatus 20. A ZrBON film was formed as follows. However, the present invention is not limited to this, and the ZrBON film may be formed by carrying out the coating process and the oxidation process with different apparatuses.

  DESCRIPTION OF SYMBOLS 10 ... Semiconductor device, 11 ... Silicon substrate, 12 ... Wiring layer, 13 ... Insulating layer, 14 ... Adhesive layer, 15 ... Silicon penetration electrode (TSV), 16 ... Barrier insulating film, 20 ... Film-forming apparatus, 21 ... Load lock Chamber 22 22 Core chamber 22 a Transfer robot 23 Deposition chamber 24 Oxidation chamber 31 Chamber body 31 S Deposition chamber 32 Chamber lid 33 Substrate stage 34 Elevating mechanism 35 DESCRIPTION OF SYMBOLS ... Exhaust pump, 36 ... Shower plate, 37 ... Irradiation tube, 38 ... Microwave source, 39 ... Waveguide, FG ... Microwave power source, GP1, GP2 ... Gas passage, H ... Through hole, MFC1, MFC2, MFC3, MFC4 ... mass flow controller, P1 ... exhaust port, P2 ... source gas port, P3 ... excitation gas port, S ... substrate, TK ... source tank.

Claims (4)

A barrier insulating film forming method for forming a barrier insulating film on an inner surface of a hole for a through electrode included in a silicon substrate,
A coating step of covering the inner surface of the hole with a ZrBN film by supplying activated nitrogen and Zr (BH ₄ ) ₄ to the silicon substrate and nitriding the Zr (BH ₄ ) ₄ with nitrogen;
An oxidation step of supplying an oxygen radical as activated oxygen to the ZrBN film to oxidize the ZrBN film to form a ZrBON film on the inner surface of the hole. The barrier insulating film forming method according to claim 1, wherein the set of the covering step and the oxidizing step is repeated a plurality of times. In the coating step,
Nitrogen radicals, a barrier insulating film forming method according to claim 1 or 2 that forms the shape of the ZrBN film by supplying hydrogen radicals, and Zr _{(BH 4) 4} in the substrate. In the coating step,
N ₂ gas is excited to generate nitrogen radicals,
Exciting H ₂ gas to generate hydrogen radicals,
The barrier insulating film forming method according to claim 3 , wherein a partial pressure ratio (P _N2 / P _H2 ) between N ₂ gas and H ₂ gas is 3 <P _N2 / P _H2 <5.