TWI613333B - Method for forming monocrystalline silicon and wafer - Google Patents

Abstract

The invention provides a method for forming a single crystal silicon ingot and a wafer. When a single crystal silicon ingot is formed by a zone melting method, a gas containing a deuterium element is introduced into the silicon in the melting zone, so that the deuterium element is stored in the single crystal silicon ingot. In the gap, the content of carbon elements and other impurities is reduced; after the wafer is formed using a single crystal silicon ingot, the deuterium element can diffuse out when forming a component on the wafer and combine with the dangling bonds at the interface to form a more stable Structure, thereby increasing the resistance of the element to hot carriers, reducing leakage current, and improving the performance and reliability of the element.

Description

Method for forming single crystal silicon ingot and wafer

The invention relates to the field of single-crystal growth and semiconductor manufacturing in the zone melting method, in particular to a method for forming single-crystal silicon ingots and wafers.

As a semiconductor material, single crystal silicon is widely used in the field of semiconductor components, so the demand is huge, and single-crystal silicon growth by zone melting is an important method to obtain single crystal silicon.

The zone melting method is also called FZ method, that is, the suspension zone melting method. The heat energy is used to generate a melting zone at one end of the raw material rod, and then the single crystal seed crystal is welded. Adjust the temperature to slowly move the melting zone to the other end of the raw rod, and grow a single crystal through the entire raw rod with the same crystal orientation as the seed crystal. The zone melting method for preparing silicon single crystals has the following advantages: 1. Without the use of a crucible, the single crystal growth process will not be contaminated by the crucible materials; 2. Due to the effect of impurity segregation and evaporation, silicon single crystals with high resistivity can be grown.

The general method of partially melting the raw material rod is: fixing the columnar raw material rod to the chuck, a metal coil slowly moves along the length of the polycrystal and passes through the raw material rod, and passes a high-power radio frequency current in the metal coil, and an electromagnetic field of radio frequency power Eddy current will be caused in the raw material rod, and Joule heat will be generated. By adjusting the coil power, the part of the raw material rod close to the coil can be melted. After the coil is moved, the melt crystallizes into a single crystal with the same crystal orientation as the seed crystal. Another method to locally melt the raw rod is to use a focused electron beam. The entire zone melt growth device can be placed in a vacuum system, or Protected atmosphere in a closed chamber.

The gas doping method is widely used in industry to grow silicon single crystals by zone melting. This doping technique involves diluting volatile PH ₄ (N-type doping) or B ₂ H ₆ (P-type doping) gas with argon (Ar) and directly blowing it into the melting region for doping. The advantage is that manufacturers do not need to store polysilicon rods with different resistivities. However, it is still unavoidable that impurities such as carbon are introduced during the formation of single crystal silicon. At the melting temperature of silicon, carbon penetrates into the crystal lattice, and as the single crystal silicon grows and cools from the molten silicon, carbon remains in the single crystal silicon, which further affects the performance and reliability of the subsequently formed semiconductor elements.

Therefore, how to reduce the content of carbon and other impurities in the single crystal silicon and improve the performance and reliability of the semiconductor device is a technical problem that those skilled in the art need to solve.

An object of the present invention is to provide a method for forming a single crystal silicon ingot and a wafer, which can reduce the formation of impurities and improve the performance of subsequent semiconductor elements.

The invention provides a method for forming a single crystal silicon ingot, and a gas containing a deuterium element is introduced into the silicon in the melting zone.

Further, in the method for forming a single crystal silicon ingot, the gas is deuterium gas.

Further, in the method for forming a single crystal silicon ingot, the gas is a mixed gas of deuterium and one or more gases of argon, hydrogen, or nitrogen.

Further, in the method for forming a single crystal silicon ingot, the gas is a mixed gas of deuterium and argon.

Further, in the method for forming a single crystal silicon ingot, the percentage of the deuterium gas and the argon gas is 0.1% to 99%.

Further, in the method for forming a single crystal silicon ingot, the gas further includes a doping gas, and the doping gas is PH ₃ , AsH ₃ or B ₂ H ₆ .

Further, in the method for forming a single crystal silicon ingot, the gas containing deuterium is passed into the silicon in the melting zone, and the method is as follows: the raw material rod is arranged in a single crystal manufacturing device and is heated with radio frequency A gas injector attached to the coil is injected into the silicon in the melting zone.

Further, in the method for forming a single crystal silicon ingot, before passing into the melting zone, the gas containing deuterium is mixed in a gas mixing box.

Further, in the method for forming a single crystal silicon ingot, moving a radio frequency coil and a gas ejector provided in a single crystal manufacturing apparatus to move the melting zone from one end of the raw material rod to the other end.

Further, in the method for forming a single crystal silicon ingot, the above steps are repeated one or more times, and no gas is introduced during the repetition.

Correspondingly, the present invention also provides a method for forming a wafer, wherein a single crystal silicon ingot is used as a raw material to form a wafer, and the single crystal silicon ingot is formed using the method for forming a single crystal silicon ingot, and the wafer contains deuterium element.

Further, the method for forming the wafer includes the steps of sequentially performing thinning, surface grinding, polishing, edge processing, and cleaning processing on the single crystal silicon ingot to form a wafer.

Compared with the prior art, the present invention has the following advantages: When a single crystal silicon ingot is formed by the zone melting method, a gas containing deuterium is introduced into the silicon in the melting zone, so that the deuterium element is stored in the gap between the single crystal silicon ingots. Reduce the content of carbon and other impurities; after forming a wafer with a single crystal silicon ingot, When a component is formed on a wafer, deuterium can diffuse out and combine with the dangling bonds at the interface to form a more stable structure, thereby increasing the resistance of the component to hot carriers, reducing leakage current, and improving the performance and performance of the component. reliability.

20‧‧‧ Raw rod

30‧‧‧Melting zone

40‧‧‧Single crystal rod

100‧‧‧Gas injector

200‧‧‧RF heating coil

300‧‧‧Gas mixing box

400‧‧‧Quality Flow Controller

FIG. 1 is a flowchart of a method for forming a single crystal silicon ingot according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of forming a single crystal silicon ingot in a single crystal manufacturing apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a connection between a gas injector and a gas mixing box in a single crystal manufacturing apparatus according to an embodiment of the present invention.

In order to make the content of the present invention more clear and easy to understand, the content of the present invention is further described below with reference to the accompanying drawings of the description. Of course, the present invention is not limited to this specific embodiment, and general substitutions well known to those skilled in the art are also covered by the protection scope of the present invention.

Secondly, the present invention is described in detail using a schematic diagram. In detailing the examples of the present invention, for the convenience of explanation, the schematic diagram is not partially enlarged according to general proportions, and should not be used as a limitation on the present invention.

The core idea of the present invention is: when a single crystal silicon ingot is formed by the zone melting method, a gas containing deuterium element is introduced into the silicon in the melting zone, so that the deuterium element is stored in the gap between the single crystal silicon ingot, and carbon and other elements are reduced The content of impurities; after the wafer is formed using a single crystal silicon ingot, the deuterium element can diffuse out when forming a component on the wafer and combine with the dangling bonds at the interface to form a more stable structure, thereby increasing the component's heat load. It can reduce the leakage current and improve the performance and reliability of components.

The invention provides a method for forming a single crystal silicon ingot. A gas containing deuterium is introduced into the silicon in the melting zone. Specifically, the gas may be simple deuterium, or deuterium and argon, hydrogen, or nitrogen. A mixed gas of one or more kinds of gases, and a preferred combination in the mixed gas is a mixed gas of deuterium and argon, and the percentage of the deuterium and argon is 0.1% to 99%, for example, 50%, specifically It can be determined according to the requirements of the process and is not limited again.

The gas also includes a doping gas. The doping gas is PH ₃ , AsH _3, or B ₂ H _6. After mixing with a gas containing deuterium, the gas is directly passed into the silicon of the melting region for N-type or P-type doping. .

Specifically, please refer to FIG. 1, which is a flowchart of a method for forming a single-crystal silicon ingot according to an embodiment of the present invention. As shown in FIG. 1, in step S01, a raw material rod is fixed to a chuck. The heating coil moves slowly along the length of the raw material rod and passes through the raw material rod, a melting zone is generated at one end of the raw material rod, and then a single crystal seed crystal is welded, and the deuterium-containing element is sprayed into the molten zone by a gas ejector. gas. In this embodiment, a schematic diagram of forming a single crystal silicon ingot by using a single crystal manufacturing apparatus is shown in FIG. 2. The single crystal manufacturing apparatus includes a gas injector 100 and a radio frequency heating coil 200. The gas injector 100 The radio frequency heating coil 200 has the same shape as the radio frequency heating coil 200, and surrounds the raw material rod 20 together, and the gas injector 100 is fixedly connected to the radio frequency heating coil 200. The radio frequency heating coil 200 generates a melting zone 30 at one end of the raw material rod 20. The gas ejector 100 injects a gas containing deuterium into the melting zone 30 and forms a single crystal rod 40 after cooling. The seeds are the same.

In step S02, the radio frequency heating coil 200 and the gas ejector 100 are moved, so that the melting zone 30 is moved from one end to the other end of the raw material rod 20, and a complete single crystal is finally formed. The rod 40 is a single crystal silicon ingot.

The gas ejector 100 includes a circular tube, an air inlet end is provided on the circular tube, and a plurality of air holes are provided on the circular tube, so that the doping gas flow can be more uniformly distributed around the melting zone. The absorption rate of the doped gas in the melting region is greatly increased, thereby improving the resistance uniformity of the vapor-doped silicon single crystal and saving the doping source. The single crystal manufacturing device further includes a gas mixing box 300 and a mass flow controller 400. The connection diagram is shown in FIG. 3, the gas mixing box 300 has a cooling device, and an air outlet of the gas mixing box 300 and The gas injector 100 is connected, the mass flow controller 400 is connected to the air inlet of the gas mixing tank 300, and is used to control the gas flowing into the gas mixing tank 300. The single crystal manufacturing device includes A plurality of mass flow controllers 400 are used to control different gases to pass into the gas mixing box 300 for mixing, and only two are marked in the third figure. The gas containing deuterium is introduced into the gas mixing box 300 through the mass flow controller 400 for mixing and cooling, and then is transmitted to the gas ejector 100, and then injected into the melting zone 30 for doped growth.

The introduction of a gas containing deuterium in the melting zone 30 can control the defects such as point defects and carbon agglomeration, which are generated in the single crystal silicon ingot formed later, reduce the generation of such defects, and store the deuterium element. In the gap between the single crystal silicon ingots, the content of carbon elements and other impurities can be reduced. After the subsequent formation of the wafer, when the element is fabricated on the wafer, the deuterium element can diffuse out and combine with the dangling bonds at the interface. A more stable structure is formed, thereby increasing the resistance of the device to hot carriers, reducing leakage current, and improving the performance and reliability of the device.

In general, the solubility of most impurities in solidified silicon is lower than that of silicon in the melting zone. Therefore, a large amount of impurities can be transferred through the melting zone, reducing the amount of impurities in the single crystal rod formed after cooling, making the impurities constantly To the end of the raw crystal rod away from the single crystal rod Aggregate, and finally remove the raw rod containing a large amount of impurities by cutting to form a single crystal rod containing a small amount of impurities. In order to continuously reduce the content of impurities in the single crystal rod, the above steps may be repeated one or more times. Therefore, the method for the single crystal silicon ingot further includes step S03: repeating steps S01 and S02 one or more times, and it is not necessary when repeating The gas containing deuterium is introduced to continuously reduce the impurity content in the single crystal rod. The specific number of repetitions is determined according to the actual process conditions, and is not limited here. After that, the formed single crystal silicon ingot can be rounded according to the diameter of the required wafer to form a regular cylindrical shape, and then the regular single crystal silicon ingot is fabricated to form a wafer.

In another aspect of this embodiment, a method for forming a wafer is also proposed. The wafer is formed using a single crystal silicon ingot as a raw material, and the single crystal silicon ingot is formed using the method for forming a single crystal silicon ingot as described above. The wafer contains deuterium-doped atoms.

Specifically, the method for forming a wafer includes the steps of: performing thinning, surface grinding, polishing, edge processing, and cleaning processing on the single crystal silicon ingot in order to form a wafer.

Subsequent elements can be formed on the wafer. As the deuterium element is stored in the gap between the wafers, the content of carbon and other impurities is reduced, and the deuterium element can diffuse out and combine with the dangling bonds at the interface to form a more stable Structure, thereby increasing the resistance of the element to hot carriers, reducing leakage current, and improving the performance and reliability of the element.

In summary, in the method for forming a single crystal silicon ingot and a wafer provided by the present invention, when a single crystal silicon ingot is formed by a zone melting method, a gas containing deuterium is introduced into the silicon in the melting zone, so that the deuterium element is stored in In the gap between single crystal silicon ingots, the content of carbon elements and other impurities is reduced. When a single crystal silicon ingot is used to form a wafer, the deuterium element can diffuse out when it is formed on the wafer and combine with the dangling bonds at the interface. , Forming a more stable structure, thereby increasing the resistance of the element to hot carriers, reducing leakage current, and improving the performance and reliability of the element.

The above are only preferred embodiments of the present invention, and do not play any limiting role on the present invention. Any person skilled in the art, within the scope not departing from the technical solution of the present invention, make any equivalent replacement or modification to the technical solution and technical content disclosed in the present invention without departing from the technical solution of the present invention. The content still falls within the protection scope of the present invention.

Flow chart without label

Claims (9)

A method for forming a single crystal silicon ingot, which uses a zone melting method to form a single crystal silicon ingot, includes: passing a gas containing a deuterium element into the silicon in a melting zone, and the method is performed by: manufacturing on a single crystal A gas ejector surrounding a raw material rod in the device and fixedly connected to an RF heating coil is sprayed into the silicon in the melting zone; moving the RF heating coil and the gas ejector provided in the single crystal manufacturing device makes the The melting zone is moved from one end to the other end of the raw material rod; and the steps of moving the radio frequency heating coil and the gas ejector are repeated one or more times, and no gas is passed in when repeated. The method for forming a single crystal silicon ingot according to claim 1, wherein the gas is deuterium gas. The method for forming a single crystal silicon ingot according to claim 1, wherein the gas is a mixed gas of deuterium and one or more gases of argon, hydrogen, or nitrogen. The method for forming a single crystal silicon ingot according to claim 3, wherein the gas is a mixed gas of deuterium and argon. The method for forming a single crystal silicon ingot according to claim 4, wherein the percentage of deuterium and argon is 0.1% to 99%. The method for forming a single crystal silicon ingot according to any one of claims 1 to 5, wherein the gas further includes a doping gas, and the doping gas is PH ₃ , AsH ₃ or B ₂ H ₆ . The method for forming a single crystal silicon ingot according to claim 1, wherein the gas containing deuterium is mixed in a gas mixing box before passing into the melting zone. A method for forming a wafer includes: A method according to any one of claims 1 to 7 is used to form a single crystal silicon ingot; the single crystal silicon ingot is used as a raw material to form a wafer, and the wafer contains a deuterium element. The method for forming a wafer according to claim 8, further comprising: sequentially performing thinning, surface grinding, polishing, edge processing, and cleaning processing on the single crystal silicon ingot to form the wafer.