JP2010226136A - Method of manufacturing semiconductor thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a semiconductor single-crystal thin film formed of a high quality group-IV element, and a semiconductor polycrystalline thin film, using the advantage of a sputtering method having high material utilization efficiency, large area responsiveness, and high safety. <P>SOLUTION: It is important to use a mixed sputtering gas of a noble gas and hydrogen, lower the achieved lowest pressure of a vacuum vessel to an ultra-high vacuum region that is lower than 1×10<SP>-7</SP>Torr, carry out sputtering using a magnetron system, maintain the pressure of a sputtering gun including a sputtering target lower than 1×10<SP>-7</SP>Torr when a sputtering gas is not run between sputtering film formation processes, and always maintain the purity of the sputtering target at high purity. Only through the combination of them, they function complementarily, the purity of the sputtering target is always maintained at high purity, the amount of mixture of oxygen into a deposited thin film is set equal to or lower than the limit of detection, damages and etching effect on the deposited thin film are prevented, and a high-quality and high-purity group-IV semiconductor crystal at practical level can be formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a single-crystal or polycrystalline semiconductor thin film manufacturing apparatus and method. Furthermore, the present invention relates to a new Group 4 single crystal or polycrystalline semiconductor thin film manufacturing apparatus and method using a method of sputtering a raw material solid material sputtering target.

The Group 4 based semiconductor, Si, Ge, crystals of C, and _{Si 1-x Ge x, Si} 1-y C y, consists of 4 group elements such as Si _1-xy Ge _x C _y mixed crystal (mixed crystal ) Here, x and y are ratios of elements to be mixed, which are called composition ratios and mean 100x and 100y%, respectively. When these semiconductor thin films are formed on a single crystal substrate, the substrate is amorphous when formed on one large single crystal (single crystal) thin film over the entire substrate or on a glass substrate. Therefore, it becomes a polycrystalline thin film in which small crystals (grains) are gathered.

Si single crystal is a central semiconductor material constituting the present LSI (Large Scale Integrated Circuit). However, became semiconductor is a carrier responsible for conduction electrons and speed of the holes faster _{Si 1-x Ge x, Si} 1-xy Ge x C y as used many single crystals of mixed crystal, such as. Polycrystalline Si or amorphous Si is used for a transistor for driving a flat panel display (FPD) formed on glass and a transistor for a peripheral circuit. It is expected that a mixed crystal of a polycrystalline body having a high carrier speed is used for the FPD transistor.

The first method usually used for forming these semiconductor thin films is to use a gas containing these elements as a raw material, thermally decompose this gas on the substrate to be deposited, and form a semiconductor thin film containing these elements. It is a method of forming. For example, the Si thin film can be obtained by thermally decomposing SiH ₄ on the substrate, and the Si _1-x Ge _x thin film can be obtained by simultaneously pyrolyzing SiH ₄ and GeH ₄ gases on the substrate. At this time, unnecessary H ₄ = 2H ₂ is desorbed from the substrate. Methods using this principle include chemical vapor deposition (CVD) and gas source molecular beam epitaxy (GSMBE).

The second method is a method of forming a thin film by melting a solid material and depositing the vapor on a deposition target substrate. For example, in the Si _1-x Ge _x thin film, solid Si and solid Ge are melted in a small crucible, and vapor emitted from the crucible is simultaneously deposited on a deposition target substrate to form a thin film. As a method using this principle, there is a solid source molecular beam epitaxy (SSMBE) method.

  As a third method, there is a sputtering method. In this method, a solid material that is a raw material is accelerated and irradiated with ions of a rare gas so that the solid material is physically sputtered by the ions, and the raw material atoms sputtered out of the solid material are opposed to each other. This is a method of forming a semiconductor thin film by depositing on an installed substrate. A gas used for sputtering is called a sputtering gas, and a solid material to be sputtered is called a sputtering target.

In the first method using a gas as a raw material, the ratio of the gas deposited on the substrate in the gas passing through the reaction vessel is low, and the utilization efficiency of the raw material is usually as low as several percent or less. In the second method for melting a solid material, the melting range is usually narrow and the vapor generation source is narrow, so that it is difficult to form a thin film uniformly on a large-area substrate.
The sputtering method, which is the third method, can increase the sputtering target, and can form a film with a large area. Further, since the sputtered atoms are attached to the opposing substrate, the raw material atoms are transferred from the sputter target to the substrate, and the utilization efficiency of the raw material is very high. In addition, although the source gas is toxic, the sputtering method has high advantages such as high safety, and no toxic gas processing device or safety device is required and handling is easy.
Sputtering is mainly used to produce polycrystalline thin films such as insulators and metals, and amorphous thin films.

  As a method of ionizing the sputtering gas for sputtering the sputtering target, a DC method in which a direct current (DC) voltage is applied between the sputtering target and the substrate to discharge the sputtering gas, and a high frequency between the sputtering target and the substrate is used. An RF method that discharges sputtering gas by applying (RF) AC voltage, a magnet is provided on the back side of the sputtering target, and a magnetic field is applied in the vicinity of the sputtering target so that at least a part thereof is parallel to the sputtering target. The magnetron system is divided into a DC magnetron system in which a DC voltage is applied between the sputtering target and the substrate, and an RF magnetron system in which a high-frequency AC voltage is applied to the magnetron system.

Sputtering is performed in a vacuum reaction vessel (chamber). There is a technique in which a single crystal of Si can be obtained by setting the minimum pressure in the reaction vessel to about 1 × 10 ⁻⁸ Torr or less, using Ar as a sputtering gas, and performing sputtering at a deposition substrate temperature of around 550 ° C. Yes (see Patent Document 1).

However, if unnecessary gases such as oxygen and H ₂ O at the lowest possible pressure remain, a high-purity crystal thin film cannot be obtained. For example, in order to suppress mixing of impurities, the ultimate pressure is lowered to an ultra-high vacuum (UHV) region of less than 1 × 10 ⁻⁸ Torr, and furthermore, high-purity Ar is flowed as a sputtering gas introduced during sputtering film formation. However, a high oxygen concentration of about 10 ⁻¹⁹ / cm ² to 10 ⁻²⁰ / cm ² remains at the crystal interface or the crystal surface, and high quality crystals cannot be obtained (see Non-Patent Document 1). For these reasons, the method of Patent Document 1 cannot avoid mixing impurities, and has not been put to practical use as a practical Group 4 single crystal semiconductor thin film manufacturing method.

Therefore, as a method for removing oxygen, which is a factor that lowers the purity of crystals, it has been studied to add hydrogen as a sputtering gas to Ar gas.
It was reported that when 53% of hydrogen was added to Ar as a sputtering gas using a vacuum vessel having a minimum ultimate pressure of 1 × 10 ⁻⁷ Torr (see Non-Patent Document 2).

  In addition, there is an example in which hydrogen is added to the sputtering gas using an electron cyclotron resonance (ECR) plasma apparatus. In this case, the etching effect of the substrate by hydrogen is seen, and the crystal quality of the formed thin film is deteriorated. Has been reported (see Non-Patent Document 3). Therefore, in general, a method of using an electron cyclotron resonance (ECR) plasma apparatus and mixing hydrogen into a sputtering gas is not considered as a method of improving the crystal quality of a semiconductor thin film.

Also disclosed is a technique in which a silicon target and a substrate are arranged in a magnetron sputtering apparatus, and a silicon thin film is formed on the substrate using a mixed gas of hydrogen gas and Ar gas (however, the hydrogen gas content is 90% or more) as a sputtering gas. (See Patent Document 2). With the technique described in Patent Document 2, it is possible to form a polycrystalline silicon thin film on glass, but the mixing ratio of hydrogen gas is 90% or more as in the above example in which 53% of H ₂ is added to Ar. Since it is high, etching with hydrogen gas and amorphization become problems, and it is not suitable for forming a single crystal thin film.

A method of mixing hydrogen as a sputtering gas has been used to form an amorphous semiconductor thin film. When sputtering is performed by lowering the deposition substrate temperature to 400 ° C. or lower, the thermal energy for crystallization is insufficient, the crystallization driving force of the deposited film is lowered, and the deposited film is likely to be amorphous. When it is made amorphous, bonds between atoms are broken and dangling bonds are generated in the atoms, which deteriorates the electrical characteristics of the amorphous film. When hydrogen is bonded to the dangling bonds, the dangling bonds disappear as a result, so that the electrical characteristics of the amorphous film are improved. For example, amorphous Si in which hydrogen is bonded to dangling hands is called hydrogenated amorphous Si.
Therefore, hydrogen mixed as a sputtering gas is used for film formation of hydrogenated amorphous Si. There is also a technology in which hydrogenated amorphous Si in which hydrogen is mixed in a deposited film can be obtained by lowering the deposition substrate temperature to 400 ° C. or lower and sputtering using a sputtering gas mixed with hydrogen (patent) Reference 3).

  On the other hand, when a single crystal or polycrystal group 4 semiconductor thin film is formed by sputtering, generally, when hydrogen is mixed into the sputtering gas, the deposited film is etched or amorphized, and the crystal quality of the semiconductor thin film is reduced. It is not considered a way to increase.

Further, when a mixed crystal such as Si _1-x Ge _x is formed on Si _1-y Ge _y having a composition ratio y different from the value of x (y includes a value of 0, and when y = 0, Si If the composition ratio is different, the atomic spacing (lattice constant) is different, so that defects occur between the two layers (interface) or between the Si substrate and the deposited film, and the crystallinity of the deposited film Gets worse. Such a phenomenon is seen at 680 ° C. or higher.

  In addition, when depositing on a substrate by sputtering, it is necessary to clean the surface of the substrate to be deposited before deposition. Cleaning is performed by a reverse sputtering method in which impurities on the surface are physically removed by irradiating the surface of the substrate to be deposited (the target to be sputtered is opposite to the sputtering during film formation in which the sputtering target is irradiated with ions, that is, sputtering). Is generally performed.

There is also a method of cleaning the surface of the substrate to be deposited by thermal annealing. When thermal annealing is performed at a high temperature of 900 ° C. or higher, impurities are effectively detached from the surface, and the surface of the substrate becomes flat by migration of surface Si atoms by heat.
However, this requires accurate removal of residual oxygen and residual H ₂ O in a vessel that undergoes thermal annealing. If there is a residual gas, it reacts with the substrate surface and the surface cannot be cleaned.
For this reason, it has been common for conventional sputtering apparatuses not to have an annealing mechanism at 900 ° C. or higher.

Further, in order to keep the pressure in the reaction vessel below 1 × 10 ⁻⁷ Torr, it is necessary to continuously exhaust the reaction vessel. The sputtering gas is exhausted with a system that is suitable for exhausting the sputtering gas and is exhausted by an exhaust device using a rotation mechanism based on the exhaust principle. An example of the exhaust device is a turbo molecular pump.
However, if the sputtering gas is continuously exhausted, the gas adheres to the exhaust device using the rotation mechanism, and there is a problem that the ultimate pressure when the sputtering gas is not flowing increases. In particular, since the material on the surface of the sputter target is transferred to the deposition target substrate, if the cleanliness of the surface of the sputter target cannot be maintained, the quality of the deposited crystal is directly affected.

Japanese Patent Publication No. 2758948 JP-A-3-162565 Japanese Patent Laid-Open No. 6-053137

T. T. et al. Ohmi, K .; Hashimoto, M .; Morita, T .; Shibata, “Journal of Applied Phisics”, 1991, 69, p. 2062-2071 G. F. Feng, M .; Katiyar, N .; Maley, J .; R. Abelson, “Physics Letter”, 1991, 59, p. 330-332 Masafumi Minamori, Kimihiro Sasaki, Yasunobu Hata, “Low-temperature epitaxial growth of Si by ECR-assisted RF sputtering”, Proceedings of the 62nd JSAP Scientific Lecture, Proceedings of the 62nd JSAP Scientific Lecture, Japan Society of Applied Physics, September 11, 2001, No. 2, p. 682

  As described above, there are few reports on the formation of single crystal semiconductor thin films that require precise atomic arrangement, especially group 4 semiconductor single crystal thin films (also called epitaxy growth) by sputtering, and sufficient practical quality is obtained. It has not reached.

  The present invention makes use of the advantages of a sputtering method having high raw material utilization efficiency, large area correspondence, and high safety, and manufactures a semiconductor single crystal thin film composed of a high-quality group 4 element and a semiconductor thin film forming a semiconductor polycrystalline thin film An object is to provide an apparatus and method.

In order to achieve the above object, a semiconductor thin film manufacturing apparatus according to claim 1 is a semiconductor thin film manufacturing apparatus for forming a single crystal or polycrystalline thin film, and the reaction container and the pressure in the reaction container are always set to 1 × 10. ^-7 with the first pressure setting means set to less than ^-7 Torr and the substrate placed in the reaction vessel maintained at a pressure in the reaction vessel set by the pressure setting means greater than 400 degrees and 680 degrees Heating means for heating to a temperature up to, introduction means for introducing a mixed gas containing a rare gas and hydrogen gas into the reaction vessel, and the heating means using the mixed gas introduced by the introduction means as a sputtering gas And a sputtering means for sputtering a sputtering target containing a Group 4 element by a magnetron method on the substrate heated in step (1).

  According to a second aspect of the present invention, in the semiconductor thin film manufacturing apparatus according to the first aspect, the hydrogen gas content of the mixed gas introduced by the introducing means is 30% or less.

  According to a third aspect of the present invention, in the semiconductor thin film manufacturing apparatus according to the first aspect, the apparatus includes at least one other container connected via a blocker capable of blocking communication with the reaction container. And a transfer means for transferring the substrate from the separate container to the reaction container or transferring the substrate from the reaction container to the separate container.

  According to a fourth aspect of the present invention, in the semiconductor thin film manufacturing apparatus according to the first to third aspects, the first pressure setting means does not have a first exhaust means for exhausting using a rotation mechanism and a rotation mechanism. When the sputtering gas is introduced into the reaction vessel, the sputtering gas is exhausted by the first exhausting means, the pressure is set, and the sputtering gas is introduced. If not, the pressure is set by exhausting with the second exhaust means.

  According to a fifth aspect of the present invention, in the semiconductor thin film manufacturing apparatus according to the first to fourth aspects, the sputtering means includes a container on which the sputtering target is placed, and a second pressure setting means for setting the pressure of the container. It is characterized by having.

The semiconductor thin film manufacturing method according to claim 6 is a semiconductor thin film manufacturing method in which a single crystal or polycrystalline thin film is formed by sputtering, and the step of setting the pressure in the reaction vessel to always less than 1 × 10 ⁻⁷ Torr; A step of placing the substrate in the reaction vessel while maintaining the pressure in the reaction vessel, heating the substrate to a temperature greater than 400 degrees and up to 680 degrees, and including a rare gas and a hydrogen gas. A step of introducing a mixed gas into the reaction vessel; and a step of sputtering a sputter target containing a group 4 element on a heated substrate by using a magnetron method with the introduced mixed gas as a sputtering gas. To do.

The method of manufacturing a semiconductor thin film according to claim 7 includes a step of placing a Si single crystal substrate in a reaction vessel, a pressure in the reaction vessel of 5 × 10 ⁻⁹ Torr or less and a vacuum state of 900 to 1100. The step of thermally annealing at a temperature of between 850 degrees, or introducing a gas containing hydrogen into the reaction vessel and thermally annealing at a temperature of between 750 and 1100 degrees, and the pressure in the reaction vessel is always 1 × The step of setting the pressure to less than 10 ⁻⁷ Torr and placing the substrate in the reaction vessel while maintaining the set pressure in the reaction vessel, and setting the substrate to a temperature between 400 ° C. and 680 ° C. A step of heating, a step of introducing a mixed gas containing a rare gas and hydrogen gas into the reaction vessel, and a sputter containing a Group 4 element on the heated substrate using the introduced mixed gas as a sputtering gas. Characterized by a step of sputtering by magnetron system Target.

  According to the first aspect of the present invention, in the production of a semiconductor thin film for forming a single crystal or polycrystalline thin film, the sputtering is performed by the magnetron method by the sputtering means, so that the plasma is concentrated on the sputter target side. Less effective and less damage to the deposited film. In addition, since there is no external plasma generating device unlike the ECR plasma device, the etching effect of the deposited thin film by active hydrogen generated in the ECR plasma device can be suppressed.

In addition, the pressure of the reaction vessel is always set to an ultra-high vacuum region of less than 1 × 10 ⁻⁷ Torr by the first pressure setting means, and the pressure is extremely high even when the substrate is placed on the reaction vessel. Since the vacuum is maintained, it is possible to sufficiently reduce the amount of residual oxygen and residual H ₂ O in the reaction vessel, which cannot be achieved by the magnetron method alone.

In addition, hydrogen is introduced as a sputtering gas by the introducing means, so that hydrogen is combined with oxygen to remove oxygen, effectively reducing residual oxygen and residual H ₂ O in the container. There is an effect that oxygen and H ₂ O can be sufficiently reduced in the semiconductor thin film. Further, not only the residual oxygen in the container but also a small amount of residual oxygen can be removed when it adheres to the surface during film formation. At the same time, in order to prevent the deposited atoms from aggregating due to hydrogen adsorbing as needed, an atomically flat, uniform and flat group 4 semiconductor thin film, which was not possible with the magnetron method and ultrahigh vacuum pressure, can be obtained.
In particular, a mixed crystal composed of a plurality of elements such as a Si _1-x Ge _x mixed crystal semiconductor thin film has a strong property that one element, for example, Ge aggregates in this case, but this phenomenon is suppressed. This makes it possible to form an atomically flat and homogeneous mixed crystal thin film.

  In addition, when the heating temperature of the substrate is set to a temperature between 400 ° C. and 680 ° C. by the heating means, when the hydrogen is mixed as the sputtering gas, amorphization or crystallinity due to a temperature drop is caused. Deterioration can also be prevented. In addition, when the substrate temperature is 420 ° C. or higher, hydrogen mixed as a sputtering gas is easily easily desorbed from the deposition curtain, and unnecessary hydrogen does not remain in the crystal, so that a thin film with high crystallinity is formed. .

  Therefore, by using a magnetron type sputtering method, the pressure is always set to ultrahigh vacuum, hydrogen is introduced as a sputtering gas, and the substrate is heated to a temperature between 400 ° C. and 680 ° C. It functions in a complementary manner and can suppress oxygen contamination into the thin film, damage to the thin film, etching effect, amorphization, etc. For the first time, extremely high quality and high purity that could not be achieved by individual means alone A practical semiconductor thin film can be formed.

  According to the second aspect of the present invention, since the hydrogen gas content of the mixed gas is 30% or less, etching and amorphization that occur when the mixing ratio of hydrogen is high do not easily occur.

According to the invention described in claim 3, by connecting the reaction vessel and the separate vessel via the blocker, 1 × 10 ⁻⁷ Torr without returning the pressure of the reaction vessel to the atmospheric pressure even when transferring the substrate. Since the inside of the reaction vessel can be kept clean, the sputter target can also be kept at a high purity. Further, the effect of eliminating residual oxygen and residual H ₂ O in the reaction vessel can be maintained to the maximum.

  According to the invention of claim 4, the first pressure setting means has a first exhaust means for exhausting using a rotating mechanism, and a second exhaust means for exhausting without having a rotating mechanism, When the sputtering gas is introduced into the reaction vessel, the pressure is set by exhausting the sputtering gas by the first exhaust means, and when the sputtering gas is not introduced, it is exhausted by the second exhaust means. Since the pressure is set, the inside of the reaction vessel can always be maintained in an ultrahigh vacuum state, and the sputter target can be maintained with high purity. Further, oxygen mixed in the deposited film is not detected, and an extremely high quality and high purity group 4 semiconductor crystal can be formed.

According to the invention of claim 5, since the sputtering means has the container on which the sputtering target is placed and the second pressure setting means for setting the pressure of the container, the degree of vacuum is 1 when the substrate is transferred. Even when the pressure drops to 10 ⁻⁷ Torr or less, the container on which the sputtering target is placed can always be maintained in an ultrahigh vacuum. For this reason, the pressure inside the container on which the sputter target is placed can always be maintained in an ultra-high vacuum state, and the sputter target can be kept at a high purity, thereby forming an extremely high quality and high purity semiconductor thin film. it can.

  According to the invention of claim 6, magnetron sputtering is used, the pressure is set to an ultrahigh vacuum, hydrogen is introduced as a sputtering gas, and the substrate is heated to a temperature between 400 ° C. and 680 ° C. As a result, it is possible to suppress oxygen contamination to the thin film, damage to the thin film, etching effect, amorphization, etc., which are practically possible with extremely high quality and high purity that could not be achieved by individual means alone. A semiconductor thin film can be formed.

According to the seventh aspect of the present invention, the Si single crystal substrate is placed in a reaction vessel, the pressure in the reaction vessel is set to a vacuum state of 5 × 10 ⁻⁹ Torr or less, and between 900 and 1100 ° C. Since the thermal annealing is performed at the temperature of, the separation of the impurities from the surface by effectively making a high vacuum is effectively performed, and the surface Si atoms are migrated by the heat to obtain a clean surface that is atomically flat. The quality of the crystals deposited on the substrate increases.
Alternatively, since thermal annealing is performed at a temperature between 750 and 1100 ° C. in the reaction vessel in a gas atmosphere containing hydrogen, residual oxygen and residual H ₂ O are effectively removed by hydrogen, and 5 × 10 ⁻⁹ Torr. The following pressures can be achieved. Also, by introducing hydrogen, even if the Si single crystal substrate is annealed at a temperature as low as 750 ° C., there is no surface contamination, cleaning proceeds, and an atomically flat Si surface optimal for crystal growth can be obtained. .

It is the schematic of the semiconductor thin film manufacturing apparatus which is one Embodiment of this invention. It is an X diffraction spectrum for evaluating the crystal quality of the superlattice layer of Si _1-x Ge _x and Si was deposited by the method of the present invention using Ar and hydrogen as a sputtering gas. Is an X diffraction spectrum for using only Ar as a sputtering gas to evaluate the crystal quality of the superlattice laminate film of the formed Si _1-x Ge _x and Si for comparison.

By reducing the ultimate pressure of the reaction vessel to an ultra-high vacuum region of less than 1 × 10 ⁻⁷ Torr, the amount of residual oxygen is sufficiently reduced, and at the same time, there is an effect of removing oxygen by combining with oxygen. By introducing hydrogen, the residual oxygen and residual H ₂ O in the container are effectively reduced, and oxygen contamination into the semiconductor thin film is sufficiently reduced, and the amount of residual oxygen in the crystal is the detection limit. Thus, a high-quality, high-purity group 4 semiconductor crystal of a practical level can be formed.

At the same time, it is indispensable that the reaction vessel and the sputtering target are not contaminated with oxygen or H ₂ O impurities. If a factor that causes contamination of the reaction vessel and the sputtering target with oxygen or H ₂ O impurities occurs between the sputter deposition and the sputter deposition, the minimum pressure reached in the reaction vessel is less than 1 × 10 ⁻⁷ Torr. Thus, the effect of removing impurities by hydrogen is reduced. By connecting the reaction vessel and another vessel as a sputtering device via a vacuum blocker, the pressure of the reaction vessel can be maintained at less than 1 × 10 ⁻⁷ Torr even when the substrate to be deposited is put in and out, and in the reaction vessel, Impurity contamination of the sputter target does not occur.

In addition, this apparatus is equipped with a turbo molecular pump using a rotating mechanism based on the exhaust principle, suitable for exhausting the sputter gas, to the reaction container or another container, or both containers via a vacuum blocker. Installing. The sputtering gas is exhausted using a turbo molecular pump.
The reaction vessel is equipped with a sputter ion pump that can easily obtain a high degree of vacuum of less than 1 × 10 ⁻⁸ Torr without using a rotating mechanism for the evacuation principle via a vacuum blocker. The turbo molecular pump exhausts the sputter gas to increase the minimum pressure that can be obtained, but the sputter ion pump can exhaust from the reaction vessel when the sputter gas is not flowing. It can be easily obtained, and the inside of the reaction vessel can always be kept below 1 × 10 ⁻⁸ Torr.

A sputter gun including a sputter target is attached to the reaction vessel through a vacuum blocker. The sputter gun is further equipped with a sputter ion pump that can easily obtain a high degree of vacuum of less than 1 × 10 ⁻⁸ Torr through another vacuum blocker.
When film formation by the sputtering method is continued, a sputtered film is deposited in a reaction vessel other than the substrate to be deposited. Therefore, the reaction vessel is exposed to the atmosphere and cleaned appropriately. However, if the vacuum blocker connected to the reaction vessel is closed, the vessel on which the sputter gun is placed is always evacuated by a dedicated sputter ion pump, so it can always be kept below 1 × 10 ⁻⁸ Torr. it can.
The reaction vessel is evacuated with a turbo molecular pump while baking, and after a minimum pressure of less than 1 × 10 ^-7 Torr is obtained, the sputter gun vacuum blocker is opened, and the reaction vessel is sputter ion pump dedicated to the reaction vessel If evacuated, the reaction vessel and the sputter gun are both maintained at a high vacuum of less than 1 × 10 ⁻⁸ Torr, the sputter target is kept at a high purity, and a high-quality, high-purity Group 4 semiconductor crystal is formed. it can.

  Sputter deposition is a magnetron system that concentrates plasma on the side of the sputtering target, suppresses the sputtering effect of the substrate to be deposited, and suppresses damage to the deposited film.

Use a mixed sputtering gas of rare gas and hydrogen, lower the ultimate pressure of the vacuum vessel to an ultra-high vacuum region of less than 1 × 10 ⁻⁷ Torr, sputtering by magnetron method, sputtering deposition and sputtering deposition It is important to keep the pressure of the sputter gun including the sputter target below 1 × 10 ⁻⁷ Torr and keep the purity of the sputter target always high when the sputtering gas is not flowing in between. For the first time, they function in a complementary manner, the purity of the sputter target is always maintained at a high purity, the amount of oxygen mixed into the deposited thin film is below the detection limit, and damage and etching effects on the deposited thin film are suppressed. A high-quality, high-purity group 4 semiconductor crystal can be formed at a practical level.

  In particular, when the amount of hydrogen mixed in the sputtering gas is 30% or less of the rare gas, a significant improvement in non-crystallization can be obtained. Furthermore, when the content is 9% or less, etching and amorphization are not observed, residual oxygen is suppressed, an atomic homogeneous film formation effect by hydrogen is effectively exhibited, and a crystal thin film made of a high-quality single element Alternatively, a mixed crystal thin film composed of a plurality of elements can be formed.

  In the case of Si with high purity, the crystal quality of the deposited thin film is enhanced by using the RF magnetron method rather than the DC magnetron method.

As a sputtering target, the sputtering target comprising single element of Si or Ge and C, Si _1-x Ge _x and Si _1-y C _y sputtering target made of a mixed crystal semiconductor is used. A plurality of these may be combined. For example, in order to form a mixed crystal thin film of Si _0.8 Ge _0.2 , a Si target and a target made of Si _0.5 Ge _0.5 may be combined.
In order to dope a semiconductor thin film, these targets may contain B, Al, Ga, In, N, P, Sb, etc. as doping elements of the semiconductor. A single target of B or Al may be used. For example, when forming a Si thin film, two targets of a pure-frame Si target and a Si target containing a doping element may be sputtered simultaneously in order to adjust the doping amount.

  A single crystal or polycrystalline material is used as the sputter target, but the crystallinity such as the crystal structure of the thin film becomes higher when the single crystal sputter target is used. In addition, when a Si single crystal substrate is used as the substrate, a high quality single crystal thin film can be formed. For this reason, when glass having an amorphous structure is used as the substrate, it becomes polycrystalline, but a high quality A crystalline thin film can be formed.

  When a polycrystalline thin film is formed using the present invention, the quality of the crystal grains is improved as described above. On the other hand, since the mixing ratio of hydrogen gas is small, defects between Glenbanderies are likely to occur. The possibility cannot be denied. However, this problem can be satisfactorily technically handled by forming a thin film by the method of the present invention and then performing hydrogen gas treatment.

The Si deposition substrate must be cleaned before sputter deposition. When cleaned, the quality, such as crystallinity, of the formed thin film increases. The atomic cleaning of the substrate is not performed by the reverse sputtering method usually used in sputtering, but is finally performed by high-temperature thermal annealing. According to the present invention, by mounting a two-chamber container structure, introduction of hydrogen, a reaction container and a sputter gun dedicated to an exhaust device that can easily obtain a high degree of vacuum without using a rotation mechanism on the exhaust principle, It is possible to obtain a vacuum degree of 5 × 10 ⁻⁹ Torr or less. By annealing the deposited Si substrate at 900 to 1100 ° C. under such a vacuum, cleaning progresses and an atomically flat and high-purity clean Si surface is obtained. In this annealing, hydrogen or a gas in which an inert gas and hydrogen are combined may be introduced to use the oxygen extraction effect by hydrogen. When annealing in a high purity gas containing hydrogen, the deposited Si substrate can be cleaned at a temperature between 750 and 1100 ° C.

FIG. 1 is a schematic view of a semiconductor thin film manufacturing apparatus 500 according to one embodiment of the present invention. A vacuum reaction vessel 1 for performing sputtering is connected to another vessel 2 via a vacuum blocker 3. The separate container 2 is connected to a turbo molecular pump 5 and a rotary pump 6 (first pressure setting means, first exhaust means) via a vacuum blocker 4. The turbo molecular pump 5 and the rotary pump 6 are exhaust devices that evacuate the separate container 2 and use a rotating mechanism for the exhaust principle. The vacuum reaction vessel 1 is further connected to a sputter ion pump 8 (first pressure setting means, second exhaust means) via a vacuum blocker 7. The sputter ion pump 8 is an exhaust device that evacuates the vacuum reaction vessel 1, and does not use a rotating mechanism for the exhaust principle.
The vacuum reaction vessel 1 is evacuated by a turbo molecular pump 5 and a rotary pump 6 using a rotation mechanism when a sputtering gas is introduced, and sputter ions not using the rotation mechanism when a sputtering gas is not introduced. Exhaust with the pump 8.
The vacuum reaction vessel 1 and the separate vessel 2 are evacuated to a pressure of 1 × 10 ⁻⁹ Torr or less by a turbo molecular pump 5 or a sputter ion pump 8.

The gas introduction tube 9 (introduction means) is a tube for introducing a sputtering gas into the vacuum reaction vessel 1.
Two magnetron-type sputtering guns 100 and 101 (sputtering means) are contained in the sputtering gun containers 102 and 103, respectively, and are connected to the vacuum reaction container 1 through the vacuum blocker 11. The connection portion with the vacuum reaction vessel 1 has shutters 180 and 181 so as to cover the sputter targets 13 and 14. Inside the sputter guns 100 and 101, there are magnets (not shown), and a magnetic field is applied so as to be parallel to the sputter targets 13 and 14. The applied magnetic field is shown at 15.

A Si single crystal sputter target 13 is installed on the sputter gun 100, and a Ge single crystal sputter target 14 is installed on the sputter gun 101. The inside of the sputter gun is cooled by water cooling. A high frequency power source 17 is connected to each of the sputter guns 100 and 101 via a matching box 16 for load matching. A high frequency power of 13.56 MHz is applied from the high frequency power source 17 to the sputter guns 100 and 101, respectively. Is done. Thus, an RF magnetron method can be performed in which high-frequency voltage is applied to the substrate and the sputtering target to perform sputtering.
Alternatively, according to the material of the sputter target, the DC magnetron method is performed in which the matching box 16 is removed, a direct current (DC) power source is connected to the sputter gun 100 or 101, and a direct current voltage is applied to the substrate and the sputter target. be able to.

Sputter ion pumps 12 (second pressure setting means) are connected to the sputter gun containers 102 and 103, respectively. The sputter ion pump 12 is an exhaust device that evacuates the sputter gun containers 102 and 103 and does not use a rotating mechanism for the exhaust principle.
The sputtering containers 102 and 103 containing the sputter guns 100 and 101 can be individually evacuated to 1 × 10 ⁻⁹ Torr or less using the sputter ion pump 12 by closing the vacuum blocker 11.

  Reference numeral 19 denotes a substrate to be deposited, and 20 denotes a placement position for placing the substrate to be deposited 19 on the vacuum reaction vessel 1. Reference numeral 21 denotes a heater (heating means) for heating the substrate to be deposited in the vacuum reaction vessel 1.

Next, the operation of manufacturing a semiconductor thin film using the above apparatus will be described below. First, the vacuum blocker 3 is closed, and the vacuum reaction vessel 1 and the sputter gun vessels 102 and 103 are evacuated to 1 × 10 ⁻⁹ Torr or less using the sputter ion pump 8.
The vacuum blocker 3 is closed, and the deposition substrate 19 is placed in the separate container 2. Next, the separate container 2 is evacuated by the turbo molecular pump 5 and the rotary pump 6 to make a vacuum of 1 × 10 ⁻⁷ Torr or less.

Next, with the degree of vacuum maintained, the vacuum blocker 3 is opened and placed at a predetermined position 20 of the vacuum reaction vessel 1. At that time, the vacuum blocker 11 is closed, and the vacuum degree of the sputtering gun containers 102 and 103 is maintained at 1 × 10 ⁻⁹ Torr or less to prevent the vacuum degree from being lowered.
Next, the vacuum blocker 3 is closed, the vacuum blocker 7 is opened, and the vacuum reaction vessel 1 is evacuated by the sputter ion pump 8 so that the pressure in the ultra-high vacuum region is 1 × 10 ⁻⁹ Torr or less.

In the vacuum reaction vessel 1 having a pressure of 1 × 10 ⁻⁹ Torr or less, the deposition target substrate 19 placed at a predetermined position 20 is heated by a heater 21 and thermally annealed at a temperature up to 1100 ° C. to be cleaned. Is done.
Next, a mixed gas of Ar and 5% hydrogen is introduced from the gas introduction pipe 9. Next, the vacuum blocker 7 is closed, the vacuum blockers 3 and 4 are opened, and the turbo molecular pump 5 is evacuated. Further, the gas introduction tube 9 sets the sputtering gas pressure in the vacuum reaction vessel 1 to a desired value between 0.5 and 10 mTorr in order to adjust the flow rate of the sputtering gas. In this embodiment, the sputtering gas pressure is set to 2 mTorr.

  Next, the temperature of the substrate 19 is adjusted to 500 ° C. by the heater 21. Next, the sputtering targets 13 and 14 are covered with shutters 180 and 181, high frequency power from the high frequency power supply 17 is applied to the sputtering guns 100 and 101, and sputtering is started. At this stage, Si and Ge scattered from the sputter targets 13 and 14 adhere to the back surfaces of the shutters 180 and 181 and do not reach the surface of the substrate 19 to be deposited.

Next, the shutters 180 and 181 are opened while the sputtering is being performed so that the sputtering target can be seen from the surface of the deposition target substrate 19. The sputtered Si and Ge atoms reach the deposition target substrate 19 to start film formation. The sputtering rate of Si and Ge is adjusted with high frequency power in advance.
The shutter 181 on the Ge single crystal sputter target 14 side is intermittently closed, and a superlattice film in which Si _1-x Ge _x and Si are alternately laminated is formed on the surface of the substrate 19 to be deposited.

After the film formation is completed, the heater 21 stops heating, the gas introduction tube 9 stops the introduction of the sputtering gas, and the high frequency power source 17 stops the power supply to the sputtering guns 100 and 101.
The deposition target substrate 19 after film formation is taken out to the side of the separate container 2 in the reverse procedure at the time of introduction into the vacuum reaction container 1. That is, the pressure of the sputtering gun containers 102 and 103 is kept at 1 × 10 ⁻⁹ Torr or lower, and the pressure of the vacuum reaction container 1 is kept at 1 × 10 ⁻⁷ Torr or lower, and the substrate 19 to be deposited is transferred to another container 2. Then, the vacuum circuit breaker 3 is closed.
After the substrate to be deposited 19 is taken out and the vacuum blocker 3 is closed, the sputter ion pump 8 is used to evacuate the vacuum vessel and the sputter gun to 1 × 10 ⁻⁹ Torr or less.

In order to evaluate the crystal quality, FIG. 2 shows Si _1-x Ge _{x formed} by using a mixed gas of Ar and 5% hydrogen as a sputtering gas and setting the substrate temperature to 400 ° C. and 500 ° C. The X-ray diffraction spectrum which measured Si about the alternately laminated film is shown.

Further, in FIG. 3, with only Ar as a sputtering gas, an X-ray diffraction spectrum of the alternate lamination film deposition was Si _1-x Ge _x and Si by setting the substrate temperature to the 480 ° C. and 500 ° C. Show. When hydrogen is introduced (FIG. 2), clear X-ray diffraction peaks of three superlattices are observed from a substrate temperature of 400 ° C. On the other hand, when only Ar is used (FIG. 3), the peak at 60.75 degree is weak, and the peak at 60.75 degree almost disappears even when the substrate temperature is 480 ° C., and hydrogen is added (FIG. 2). It can be seen that the crystallinity is further deteriorated, and that high crystal quality can be obtained by introducing hydrogen.

DESCRIPTION OF SYMBOLS 500 Semiconductor thin film manufacturing apparatus 1 Reaction container 2 Separate container 3 Vacuum blocker 4 Vacuum blocker 5 Turbo molecular pump 6 Rotary pump 7 Vacuum blocker 8 Sputter ion pump 9 Gas introduction pipe 100, 101 Sputter gun 102, 103 Sputter Gun container 11 Vacuum shut-off device 12 Sputter ion pump 13 Si single crystal sputter target 14 Ge single crystal sputter target 15 Applied magnetic field 16 Matching box 17 High frequency power supply 180, 181 Shutter 19 Substrate 19 Substrate 20 Deposition substrate Position 21 Heater

Claims (6)

In a semiconductor thin film manufacturing apparatus for forming a single crystal or polycrystalline thin film,
A reaction vessel;
Pressure setting means for setting the pressure in the reaction vessel to less than 1 × 10 −7 Torr;
Heating means for heating the substrate placed in the reaction vessel to a temperature greater than 400 degrees and up to 680 degrees while maintaining the pressure in the reaction vessel set by the pressure setting means;
At least one other container connected via a blocker capable of blocking communication with the reaction container;
Transfer means for transferring the substrate from the separate container to the reaction container, or transferring the substrate from the reaction container to the separate container;
Pressure setting means for setting the pressure in the separate container to less than 1 × 10 ⁻⁷ Torr;
Introducing means for introducing a mixed gas containing a rare gas and hydrogen gas into the reaction vessel;
Using the mixed gas introduced by the introducing means as a sputtering gas, a sputtering target made of Si or Ge or a mixed crystal of Si and Ge, which may contain a doping element, is formed on the substrate heated by the heating means by a magnetron method. A semiconductor thin film manufacturing apparatus, comprising: a sputtering means for sputtering.   2. The semiconductor thin film manufacturing apparatus according to claim 1, wherein the content of hydrogen gas in the mixed gas introduced by the introducing means is 30% or less. The pressure setting means has a first exhaust means for exhausting using a rotation mechanism, and a second exhaust means for exhausting without having a rotation mechanism,
When sputtering gas is introduced into the reaction vessel, the sputtering gas is exhausted by the first exhaust means to set the pressure,
When the sputtering gas is not introduced, the pressure is set by exhausting by the second exhaust means,
The semiconductor thin film manufacturing apparatus according to claim 1, wherein the apparatus is a semiconductor thin film manufacturing apparatus. The sputtering means includes a container on which the sputtering target is placed, and a blocker that can open and close communication between the container and the reaction container;
Pressure setting means for setting the pressure of the container;
The semiconductor thin film manufacturing apparatus according to claim 1, wherein: In a semiconductor thin film manufacturing method for forming a single crystal or polycrystalline thin film by sputtering,
A step of always setting the pressure in the reaction vessel to less than 1 × 10 −7 Torr except when the sputtering gas is introduced;
Placing the substrate in the reaction vessel while maintaining the set pressure in the reaction vessel, and heating the substrate to a temperature greater than 400 degrees and up to 680 degrees;
Introducing a mixed gas containing a rare gas and hydrogen gas into the reaction vessel;
Sputtering a sputtering target made of Si, Ge, or a mixed crystal of Si and Ge, which may contain a doping element, on a heated substrate using the introduced mixed gas as a sputtering gas by a magnetron method. A method for producing a semiconductor thin film. Placing a Si single crystal substrate in a reaction vessel;
The pressure in the reaction vessel is set to a vacuum state of 5 × 10 −9 Torr or less, and a thermal annealing step is performed at a temperature of 900 to 1100 degrees, or a gas containing hydrogen is introduced into the reaction vessel, Thermal annealing at a temperature between 1100 degrees;
Always setting the pressure in the reaction vessel to less than 1 × 10 −7 Torr except when sputtering gas is introduced;
Placing the substrate in the reaction vessel while maintaining the set pressure in the reaction vessel, and heating the substrate to a temperature greater than 400 degrees and up to 680 degrees;
Introducing a mixed gas containing a rare gas and hydrogen gas into the reaction vessel;
Sputtering a sputter target made of Si, Ge, or a mixed crystal of Si and Ge, which may contain a doping element including a group 4 element, on a heated substrate by using the introduced mixed gas as a sputtering gas by a magnetron method A method for producing a semiconductor thin film, comprising:

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