Semiconductor device manufacturing method, semiconductor device manufacturing apparatus, control program and computer storage medium

Photoresist film is used as a mask, plasma etching of a SiO2 film is selectively performed to a photoresist film, and a hole is formed. An etching gas comprising unsaturated fluorocarbon gas containing oxygen expressed with CxFyO (y/x is 1-1.5 at an integer in x, as for 4 or 5, and y) is used for the plasma etching. C4F4O gas and C4F6O gas are used for the unsaturated fluorocarbon gas containing oxygen, for example.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device manufacturing method, a semiconductor device manufacturing apparatus, a control program, and a computer storage medium, which has an etching process which etches a dielectric film containing Si by using a photoresist as a mask.

2. Description of the Related Art

In a manufacturing process of a semiconductor device, it is known to form a contact hole or the like according to an etching process which etches a dielectric film containing Si (for example, a SiO2film, a SiOC film, or the like) by using a photoresist as a mask. And, for example, in such an etching process, it is proposed to use fluorocarbon gas containing oxygen as an etching gas.

As related art which uses a gas which contains fluorocarbon gas containing oxygen as the etching gas, it is known the art of etching by use of a gas containing C5F8O2for example, so that the selectivity of the dielectric film containing Si to the photoresist (etching rate of the dielectric film containing Si/etching rate of the photoresist) become around 5.55 (see to Japanese Patent Application Laid-open No. 2005-39277 for example.).

It is also known that a mixed gas of fluorocarbon gas such as C5F8, C4F6, and C4F4O, inert gas (Ar), and oxygen, carbon monoxide is available to the etching gas for etching a dielectric film containing Si (see to Japanese Patent Application Laid-Open No. 2002-231596 for example).

SUMMARY

Conventionally, it is proposed fluorocarbon gas containing oxygen as above-mentioned. However, in the conventional art which uses such fluorocarbon gas containing oxygen in the etching process etching the dielectric film containing Si by use of the photoresist as the mask, the obtained selectivity is around 5.55.

On the other hand, in the etching process which etches the dielectric film containing Si by use of the photoresist as the mask, it is desired to develop the semiconductor device manufacturing method which enables to improve the selectivity of the dielectric film containing Si to the photoresist further for forming thinner film of the photoresist and for increasing the productivity.

The present invention is coped made in consideration of above-mentioned conventional situations. An object of the present invention is to provide a semiconductor device manufacturing method, a semiconductor device manufacturing apparatus, a control program, and a computer storage medium, which enables to improve the selectivity of the dielectric film containing Si to the photoresist in the etching process compared with the prior art.

One aspect of the present invention is a manufacturing method of a semiconductor device comprising a plasma etching step for performing plasma etching of a dielectric film containing Si formed on a substrate to be processed by use of a photoresist as a mask, wherein the plasma etching step performs the plasma etching by use of an etching gas comprising unsaturated fluorocarbon gas containing oxygen expressed with CxFyO (x is 4 or 5, y is an integer, y/x is from not less than 1 to not more than 1.5) so as to etch the dielectric film containing Si selectively to the photoresist.

Another aspect of the present invention is a manufacturing method of a semiconductor device comprising a plasma etching step for performing plasma etching of a dielectric film containing Si formed on a substrate to be processed by use of a photoresist as a mask, wherein the plasma etching step performs the plasma etching by use of an etching gas comprising C4F4O gas so as to etch the dielectric film containing Si selectively to the photoresist.

Another aspect of the present invention is a manufacturing method of a semiconductor device comprising a plasma etching step for performing plasma etching of a dielectric film containing Si formed on a substrate to be processed by use of a photoresist as a mask, wherein the plasma etching step performs the plasma etching by use of an etching gas comprising C4F6O gas so as to etch the dielectric film containing Si selectively to the photoresist.

For the etching gas, for example, mixed gas comprising C4F4O gas, at least one rare gas selected from the group consisting of Ne, Ar, Kr, and Xe, and at least one deposition removal gas selected from the group consisting of O2, N2, and CO can be used suitably.

Also, as the etching gas, mixed gas comprising C4F6O gas, C4F6gas, at least one rare gas selected from the group consisting of Ne, Ar, Kr, and Xe, and at least one deposition removal gas selected from the group consisting of O2, N2, and CO can be used suitably.

An O2gas can be used suitably for the deposition removal gas. An Ar gas can be used suitably for the rare gas. When C4F4O gas and O2gas are used, among the etching gas, it is preferred to make the ratio of the flow rate of O2gas to the flow rate of C4F4O gas (flow rate of O2gas/flow rate of C4F4O gas) into the range from not less than 1 to not more than 1.35.

In one aspect of the present invention, in the plasma etching step of the above-mentioned manufacturing method of the semiconductor device is performed by applying high-frequency power between an upper electrode and a lower electrode in a process chamber, the lower electrode in which the substrate to be processed is laid thereon and the upper electrode facing the lower electrode being arranged in the process chamber.

In this case as the high-frequency power, the first high-frequency power applied to the upper electrode and the second high-frequency power whose frequency is lower than that of the first high-frequency power applied to the lower electrode can be suitably used. Also as the high-frequency power, the first high-frequency power applied to the lower electrode, and second high-frequency power whose frequency is lower than that of the first high-frequency power applied to the lower electrode can be suitably used.

One aspect of the present invention is manufacturing apparatus of a semiconductor device comprising, a process chamber for accommodating a substrate to be processed, an etching gas supply unit for supplying an etching gas into the process chamber, a plasma generating unit for generating plasma of the etching gas supplied from the etching gas supply unit to perform plasma etching of the substrate to be processed,a control unit for controlling the plasma etching in the process chamber such that the above-mentioned manufacturing method of the semiconductor device is performed.

One aspect of the present invention is a control program to be executed by a computer, for controlling a manufacturing apparatus of a semiconductor device such that the above-mentioned manufacturing method of the semiconductor device is performed when execution.

One aspect of the present invention is a computer storage medium storing a control program to be executed by a computer, wherein the control program controls a manufacturing apparatus of semiconductor device such that the above-mentioned manufacturing method of semiconductor device is performed when execution.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.FIG. 1AandFIG. 1Benlarge and illustrate a sectional structures of a semiconductor wafer W as a substrate to be processed in a semiconductor device manufacturing method according to this embodiment.FIG. 2illustrates a sectional schematic structure of the plasma processing apparatus as a semiconductor manufacturing apparatus according to this embodiment. First, the composition of the plasma processing apparatus will be described with reference to theFIG. 2.

A plasma processing apparatus1is constituted as a capacitive-coupling parallel plates type plasma etching apparatus, in which upper and lower electrode plates are facing each other in parallel and the power supply for plasma formation is connected.

The plasma processing apparatus1has a process chamber (a processing vessel)2formed in a circular cylindrical shape made of, for example, aluminum or the like with anodized on its surface. The process chamber2is grounded. A substantially circular cylindrical susceptor supporting table4is provided at a bottom in the chamber2with an insulating plate3intervening therebetween, for mounting an object to be processed, for example, a semiconductor wafer W thereon. Further, on the susceptor supporting table4, a susceptor5is provided which constitutes a lower electrode. To the susceptor5, a high pass filter (HPF)6is connected.

Inside of the susceptor supporting table4, a refrigerant room7is provided. A refrigerant is introduced into there refrigerant room7via a refrigerant introducing pipe8, and circulates in the refrigerant room7. That cold heat is transferred to the semiconductor wafer W via the susceptor5. Thereby, the semiconductor wafer W is controlled in the desired temperature.

The susceptor5is formed such that its upper central portion is formed in a projecting circular disc shape on which an electrostatic chick11having almost the same shape as that of the semiconductor wafer W is provided. The electrostatic chuck11is configured to dispose an electrode12within an insulating material. A direct-current voltage of, for example, 1.5 kV is then applied from a direct-current power supply13connected to the electrode12to electrostatically attract the semiconductor wafer W, for example, by Coulomb force.

At on the insulating plate3, the susceptor supporting table4, the susceptor5, and the electrostatic chuck11, a gas passage14is formed for supplying a heat-transfer medium (for example, He gas or the like) to the rear surface of the semiconductor wafer W. Via the heat-transfer medium, the cold heat of the susceptor5is transferred to the semiconductor wafer W to keep the semiconductor wafer W at a predetermined temperature.

At the peripheral portion of the upper end of the susceptor5, an annular focus ring15is disposed to surround the semiconductor wafer W mounted on the electrostatic chuck11. The focus ring15is made, for example, of a conductive material such as silicon, and has a function to improve the uniformity of etching.

Above the susceptor5, an upper electrode21is provided opposed to and in parallel with the susceptor5. The upper electrode21is supported by an upper portion of the chamber2via an insulating material22The upper electrode21is composed of an electrode plate24which is made of aluminum with its surface being subjected to anodic oxidization treatment (alumite treatment) and is provided with a quartz cover and which constitutes an opposed surface to the susceptor5and has a number of discharge holes23, and an electrode supporter25made of a conductive material which supports the electrode24. The susceptor5and the upper electrode21are configured such that a distance therebetween is changeable.

A gas introducing port26is provided at the center of the electrode supporter25in the upper electrode21, and a gas supply pipe27is connected to the gas introducing port26. Further to the gas supply pipe27, a processing gas supply source30is coupled via a valve28and a mass-flow controller29. From the processing gas supply source30, an etching gas as processing gas is supplied.

To the bottom of the process chamber2, an exhaust pipe31is connected, and to the exhaust pipe31, an exhaust equipment35is connected. The exhaust equipment35comprises a vacuum pump such as a turbo-molecule pump and can evacuate the chamber2to a predetermined reduced pressure atmosphere, for example, a predetermined pressure equal to or lower than 1 Pa. Further, a gate valve32is provided on a side wall of the chamber2so that the semiconductor wafer W is carried to/from an adjacent load lock chamber (not shown) with the gate valve32opened.

A first high-frequency power supply40is coupled to the upper electrode21, and a matching device41is interposed in its power supply line. Further, a low pass filter (LPF)42is connected to the upper electrode21. The first high-frequency power supply40has frequencies within a range from 50 MHz to 150 MHz. Application of such a high frequency allows high-density plasma to be formed in a preferable dissociation state in the chamber2.

A second high-frequency power supply50is coupled to the susceptor5as the lower electrode, and a matching device51is interposed in its power supply line. The second high-frequency power supply50has frequencies within a range lower than that of the first high-frequency power supply40, so that application of a frequency in such range allows an appropriate ion action to be provided to the semiconductor wafer W that is the object to be processed without damage thereto. It is preferable that the frequencies of the second high-frequency power supply50range from 1 MHz to 20 MHz.

The action of the plasma processing apparatus1configured as described above is comprehensively controlled by a control unit60. The control unit60has a process controller61which includes a CPU and controls each part of the plasma processing apparatus1, a user interface62, and a memory unit63.

The user interface62is constituted of a key board of which a process manager executes an input operation of command to manage the plasma processing apparatus1, a display for displaying the state of operation to be visible, and the like.

In the memory unit63, control programs (software) for realizing various kind of processes which are executed in the plasma processing apparatus1by controlling of the process controller61and recipes in which processing conditions and the like are memorized are stored. And as need arises, by accessing any recipe in the memory unit63according to the instruction and the like from the user interface62and by operating the process controller61, required processes in the plasma processing apparatus1are executed under the control of the process controller61. And, as the processing program and recipes of data of processing conditions and the like, it is possible to use those stored in the computer storage medium (for example, hard disk, CD, flexible disk, semiconductor memory and the like), which can be read with a computer, or to use with on-line system those obtained by transmitting from other apparatus at any time through a private line for example.

When the dielectric film containing Si (for example, a SiO2film, a SiOC film, or the like) formed on a semiconductor wafer W is etched selectively to photoresist as a mask, using the plasma processing apparatus1having the structure described above, first, after the gate valve32is opened, the semiconductor wafer W is carried into the process chamber2from the load-lock-room which is not shown, and mounted on the electrostatic chuck11. Next, by applying DC voltage to the electrode12from the direct current power supply13, the semiconductor wafer W is electrostatic-absorbed on the electrostatic chuck11. Next, the gate valve32is closed, and then the inside of the chamber2is evacuated to the predetermined vacuum using the exhaust equipment35.

Thereafter, the valve28is opened, a predetermined etching gas is introduced from the processing gas supply source30into a hollow portion of the upper electrode21through a processing gas supply pipe27and the gas feed port26while controlling the flow rate by the mass-flow controller29, and then the etching gas is uniformly discharged to the semiconductor wafer W through discharge holes23of the electrode plate24, as shown by the arrow inFIG. 2.

Then, a pressure in the inside of the chamber2is maintained to a predetermined pressure. Thereafter, a high-frequency power having a predetermined frequency is applied to the upper electrode21from the first high-frequency power supply40. Thereby, a high frequency electric field is generated between the upper electrode21and the susceptor5as the lower electrode and then the etching gas is dissociated and plasmatized.

On the other hand, from the second high-frequency power supply50, a high-frequency power having a frequency lower than that of the first high-frequency power supply40is applied to the susceptor5which is a lower electrode. Thereby, ions in the plasma are drawn into the susceptor5side, an anisotropy of etching is enhanced by ion-assist.

Then, when the predetermined etching processing is finished, the supply of the high-frequency power and the etching gas is stopped, the semiconductor wafer W is carried out from the process chamber2, with a process opposite to the process described above.

Next, with reference toFIG. 1, a semiconductor device manufacturing method according to this embodiment will be described. As shown inFIG. 1A, a dielectric film containing Si101(for example, a SiO2film, a SiOC film, or the like) of the predetermined thickness (for example, 2000 nm) is formed on the surface of the semiconductor wafer W as a substrate to be processed. A photoresist film102of the predetermined thickness (for example, 660 nm) is formed on the surface of the dielectric film containing Si101. A predetermined pattern is transferred by exposure, the development process or the like so that the photoresist film102becomes a mask which has an opening103of a prescribed pattern. The semiconductor wafer W is carried into the process chamber2of the plasma processing apparatus1in this state.

Within the process chamber2, the photoresist film102is used as a mask, plasma etching of the dielectric film containing Si101is carried out selectively to the photoresist film102, as shown inFIG. 1B, holes104, such as a contact hole, are formed. The etching gas containing an unsaturated fluorocarbon gas containing oxygen expressed with CxFyO (x is 4 or 5, y is an integer, y/x is from 1 to 1.5, inclusive) is used for this plasma etching. For this unsaturated fluorocarbon gas containing oxygen, C4F4O gas and C4F6O gas can be used, for example.

When using C4F4O gas, as etching gas, for example, the mixed gas containing C4F4O gas, at least one rare gas selected from the group consisting of Ne, Ar, Kr, and Xe, and at least one depo-removal-gas (deposition removal gas) selected from the group consisting of O2, N2, and CO can be used suitably. In one example, the mixed gas containing C4F4O gas, Ar gas, and O2gas can be used suitably. Other gas, for instance, rare gas or the like can be added to such mixed gas if needed. When using the above-mentioned mixed gas, the ratio of the flow rate of O2gas to the flow rate of C4F4O gas (flow rate of O2gas/flow rate of C4F4O gas) preferably is in the range from 1 to 1.35, inclusive. This reason is mentioned later. As C4F4O, the structure as shown below can be used, for example.

When using C4F6O gas, as etching gas, for example, the mixed gas containing C4F6O gas, C4F6gas, at least one rare gas selected from the group consisting of Ne, Ar, Kr, and Xe, and at least one depo-removal-gas (deposition removal gas) selected from the group consisting of O2, N2, and CO can be used suitably. In one example, the mixed gas containing C4F6O gas, C4F6gas, Ar gas, and O2gas can be used suitably. As C4F6O, the structure as shown below can be used, for example.

As example 1, the plasma processing apparatus1shown inFIG. 2was used, and the above-mentioned plasma etching step was performed to the semiconductor wafer W (the photoresist film (P. R.)=660 nm, the dielectric film containing Si (SiO2film)=2000 nm) of the structure shown inFIG. 1AandFIG. 1Bwith the recipe such as shown below, and the hole104whose diameter is 0.15 μm was formed.

The processing recipe of each example shown below is read from the memory unit63of the control unit60, and is incorporated into the process controller61. When the process controller61controls each part of the plasma processing apparatus1based on the control program, the etching process as the read processing recipe is performed.Etching gas: C4F4O/Ar/O2=20/300/24 sccmPressure: 2.0 Pa (15 mTorr)Power (upper part/lower part): 2200 W (60 MHz)/1800 W (2 MHz)Interval between electrodes: 25 mmTemperature (upper part/side wall part/lower part):60/50/-10° C.Etching time: 180 seconds

The etching rate of the SiO2film in the hole part in the above-mentioned plasma etching step was 532 nm/min. The selectivity of SiO2film to the photoresist (etching rate of the SiO2film/etching rate of the photoresist) was 13.7 in the flat part, 7.2 in the facet part. The etching rate of the above-mentioned SiO2film indicates, as shown inFIG. 3, the value which is given by dividing the etching depth ‘c’ of the hole produced by etching, by the etching time. Also, the etching rate of the photoresist indicates the value which is given by dividing thickness ‘a’ etched at the flat part of the photoresist by the etching time. The selectivity of the flat part indicates, as shown inFIG. 3, the ratio of above ‘c’ to the thickness ‘a’ etched at the flat part of the photoresist for “initial photoresist film thickness” (c/a). The facet part etched aslant formed in a part of the inlet section of the opening of the photoresist, as shown inFIG. 3. The selectivity of the facet part indicates the ratio of above ‘c’ to the thickness ‘b’ etched at this facet part for “initial photoresist film thickness” (c/b) since.

As a comparative example, the plasma etching step was performed on the same conditions as above except that the etching gas was changed into C4F6/Ar/O2=20/300/17 sccm. As the result, the etching rate of SiO2film in the hole part was 539 nm/min, the selectivity of the SiO2film to the photoresist was 10.6 in the flat part and was 6.1 in the facet part.

In the above-mentioned example 1, the almost same etching rate as the case of the comparative example was obtained, and the selectivity of the SiO2film to the photoresist was improved approximately 30% in the flat part, approximately 20% in the facet part, compared with the case of the comparative example. The capability of forming deep hole (capability of forming deep hole without etch-stop) about hole-diameter of 0.15 μm was almost the same.

The graphs ofFIG. 4andFIG. 5show the changes of the etching rate (‘A’ for the example, ‘B’ for the comparative example) and the selectivity of the SiO2film to the photoresist (‘a’ for the example, ‘b’ for the comparative example) when the flow rate of O2of the etching gas is changed, in the above-mentioned example and the above-mentioned comparative example.FIG. 4shows the case of the facet part, andFIG. 5shows the case of the flat part. As shown inFIG. 4andFIG. 5, when the flow rate of C4F4O was 20 sccm, by making O2flow rate within the range from not less than 20 sccm to not more than 27 sccm and making the flow rate ratio of them (O2flow rate/C4F4O flow rate) within the range from not less than 1 to not more than 1.35, the selectivity of SiO2film to the photoresist was enlarged, compared with the case of the comparative example. When C4F4O flow rate was increased more than O2flow rate and the above-mentioned flow rate ratio was made into less than 1, the etching rate of SiO2film was decreased sharply. For this reason, the above-mentioned flow rate ratio is preferred to be at least 1 or more.

Next, as example 2, the plasma processing apparatus1shown inFIG. 2was used, and the above-mentioned plasma etching step was performed to the semiconductor wafer W (the photoresist film=660 nm, the SiO2film=2000 nm) having the structure shown inFIG. 1with the recipe as shown below, and the hole104whose diameter was 0.15 μm was formed.

The processing recipe of the example 2 shown below is read from the memory unit63of the control unit60, and is incorporated into the process controller61, and when the process controller61controls each part of plasma processing apparatus1based on the control program, the etching process as the read processing recipe is performed.Etching gas: C4F6O/C4F6/Ar/O2=10/20/300/25 sccmPressure: 2.0 Pa (15 mTorr)Power (upper part/lower part): 2200 W (60 MHz)/1800 W (2 MHz)Interval between electrodes: 25 mmTemperature (upper part/side wall part/lower part): 60/50/−10° C.Etching time: 3 minutes

The etching rate of the SiO2film in the hole part in the above-mentioned plasma etching step was 606 nm/min. The selectivity of the SiO2film to the photoresist (etching rate of the SiO2film/etching rate of the photoresist) was 8.6 in the flat part and was 6.0 in the facet part.

As the comparative example, the plasma etching step was performed on the same conditions as the above except that the etching gas was changed into C4F6/Ar/O2=20/300/20 sccm. As the result, the etching rate of SiO2film in the hole part was 533 nm/min, the selectivity of SiO2film to the photoresist was 6.0 in the flat part and was 5.0 in the facet part.

In the above-mentioned example, a higer etching rate than the comparative example was obtained, and the selectivity of the SiO2film to the photoresist was improved approximately 40% in the flat part, approximately 20% in the facet part, compared with the case of the comparative example. The capability of forming deep hole about hole-diameter of 0.15 μm was almost the same as the example 1.

According to the present embodiment, in the plasma etching step in the manufacturing method of the semiconductor manufacturing device, the selectivity of the dielectric film containing Si to the photoresist can be improved compared with the former one as described above. The present inventions are not limited to the above-mentioned embodiments, and various kinds of modification may be applied to them. For example, plasma processing apparatuses are not limited to the type of applying high frequency power to upper and lower parts with flat panel in parallel as shown inFIG. 2. The type of applying the power with two frequencies to lower electrode or other of the plasma processing apparatuses can be used.

As mentioned above, although the embodiments of the invention and the examples have are described in full detail with the drawings, the present invention is not limited to the embodiment or the examples described above. The various design variation can be made within the scope which does not deviate from the gist of the present invention.