JPH04177825A - Epitaxial growth method and chemical vapor growth device - Google Patents

Abstract

PURPOSE:To manufacture an epitaxial film, which has good properties, at low growth temperature by jetting material gas against a silicon substrate together with hydrogen gas for jetting support. CONSTITUTION:A reaction pipe 1 is vacuumized through a feed through 4 by pumps RP1, RP2, TMP, and MBP, and as material gas, a silane compound such as silicon hydride or its chloride are supplied to the reaction pipe 1 together with hydrogen gas H2 for jetting support via mass flow controllers MFC1 and MFC4 and valves V1, V5, and V7. And due to the pressure difference between the pressure inside the gas line and the pressure inside the reaction pipe 1, the material gas is jetted against the surface of the substrate 2 at high speed, and the material gas reacts upon it, and a silicon epitaxial film grows on the surface of the substrate. Hereby, a good quality of silicon epitaxial film can be achieved at high speed and low temperature on the silicon substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an epitaxial growth method and chemical vapor deposition apparatus for growing an epitaxial silicon single crystal thin film having good properties on a silicon substrate at a low temperature.

[Summary of the Invention] The present invention makes it possible to produce an epitaxial thin film with good characteristics at a low growth temperature by spraying a raw material gas together with hydrogen gas for spraying support onto a silicon substrate. .

[Prior Art] As semiconductor integration technology progresses, the design rules that determine the degree of microfabrication required in device design are being reduced year by year, and the demand for such rules is becoming stronger.

However, conventionally, the design rules required for miniaturization have been limited due to the manufacturing process for manufacturing them.

One thing that limits design rules from a manufacturing process perspective is epitaxial growth conditions.

One of the problems is the incorporation of impurities during epitaxial growth. That is, autodoping and outward diffusion from the substrate and impurity incorporation from outside the substrate.

The autodoping occurs when impurities vaporized from the substrate surface are incorporated into the epitaxially grown film again. - As an example, a case will be described in which silicon epitaxial growth is performed using SiCl4 as a raw material. Since SiCl4 is a liquid at room temperature, hydrogen is used as a bubbling gas to vaporize it. Hydrogen power 2 including SiCl4, 1000℃~130℃
When introduced onto a growth substrate heated by a reaction tube heated to a high temperature of 0°C or a high-frequency heating device, the hydrogen used there as a carrier acts to reduce 5IC14 and causes it to form on the substrate. epitaxial growth occurs.

The reduction reaction is shown in the following formula.

SiCl4(g 1+2H2(g , →5i(s ,
(Deposition)↓+4HC1(g+↑-(+) At the same time, HCI generated in the gas phase etches the substrate, and a reverse reaction or a similar reverse reaction occurs. The growth rate is determined by the balance between etching and growth.

As an example, the etching reaction of an As-doped 81 substrate is shown by the following equation.

Si: As(s)+HC1(g,-+5i
hC14-n↑+AsCl3 or AsH3↑+H2
(2) (Coefficients omitted) The impurities generated at this time are redoped into the epitaxial layer. This is autodoping, and growth occurs at atmospheric pressure (lat+I+) or at a certain reduced pressure (approximately 80 to
100 torr). The growth rate at that time is about 0.1 to 1.0 μm. At this time, although the reduction reaction of formula (1) occurs even at a lower temperature, a temperature of about 1150 to 1300° C. is required to obtain a good quality epitaxial growth layer. The problem is that impurities in the substrate are discharged into the gas phase as a result of the etching reaction of equation (2).

At this time, autodoping occurs when the impurities discharged into the gas phase are incorporated into the grown epitaxial film again. This depends on the growth temperature, pressure during growth, and growth rate. The behavior of each impurity differs depending on the type of impurity. For example, in the case of n-type impure willow, P >
Autodoping is more likely to occur in the order of A s > S b , and in general, the higher the growth temperature and the lower the growth pressure, the lower the amount of autodoping. The longer the residence time of impurities discharged from the substrate in the boundary layer region during epitaxial growth, the greater the amount of autodoping. This is called longitudinal autodoping. Similarly, doping of the grown film in the lateral direction also occurs, which impedes pattern refinement. This is called lateral autodoping.The above-mentioned outward diffusion occurs when the epitaxial growth temperature is 1150℃.
Since the temperature is quite high at ~1300° C., impurities in the substrate are diffused into the grown film due to thermal diffusion from the substrate side. Therefore, the boundary between the substrate and the epitaxial layer becomes broad.

In order to avoid the influence of out-diffusion, the influence is avoided by growing the film thicker than actually required. Particularly when a low concentration epitaxial film is required on a high concentration buried diffusion layer, a considerably long film thickness is required. Also, impurity redistribution occurs due to a decrease in substrate surface concentration. This makes it necessary to pre-dope the substrate with a relatively large amount of impurity, and that amount of impurity is wasted.

The impurity taken in from outside the substrate is caused by the high epitaxial growth temperature. Because the growth temperature is very high, evaporation and diffusion occur very quickly even if there is a very small amount of contamination source in the reactor and susceptor.
They are incorporated into the grown film and form defects, which shortens the life of minority carriers on the wafer. This means that the high temperature process increases the possibility of contamination of the grown film. −
Generally, epitaxial growth is performed relatively early in the process, and is often the process at the highest temperature of all processes. In order to minimize the occurrence of defects due to contamination such as impurities during the process, methods of introducing defects such as extrinsic gettering are used.

However, because the epitaxial temperature is high, defects introduced to the back surface etc. for gettering purposes during epitaxial growth disappear, resulting in a phenomenon in which the gettering effect is lost. Since no gettering method has so far been developed that maintains the effect even after epitaxial growth, no gettering effect can be expected in subsequent processes.

In order to solve these problems, the following measures are currently being taken.

One is to change the raw material gas. When chlorine in 5iCI4 is replaced with hydrogen one by one in a chlorine-containing system, the epitaxial growth temperature becomes lower. 5iH
For C13, it is 1100-1150°C, and for 5iH2Cl2, it is 1080-1100°C. This lowers the growth temperature and at the same time reduces the amount of MCI generated by the reaction, reducing the etching rate during growth and reducing the amount of autodoping.

When the raw material gas becomes silane gas SiH4, the reaction mechanism changes. The main reaction is thermal decomposition of SiH4 itself. In this case, the carrier gas is not necessarily hydrogen, but may be any other inert gas. In this case, thermal decomposition of silane starts at 600°C, but is carried out at a temperature of 900°C or higher due to quality problems of the grown film. Since surface etching does not occur during growth, the amount of autodoping is reduced and at the same time
Since the growth temperature can be lowered, the amount of outward diffusion is also reduced.

However, the temperature has not decreased enough yet.

As a measure to reduce autodoping and out-diffusion,
There is a two-stage growth method. In this method, a thin epitaxial growth layer is once grown on a substrate, and then a target layer is epitaxially grown with this film suppressing the diffusion of impurities. This has the advantage of not requiring changes to conventional raw materials or growth temperatures, but the process is complicated.

Next, problems with the above-mentioned epitaxial film from the viewpoint of integration of semiconductor elements will be described.

As semiconductor devices become more integrated, the rules for active parts of devices are being reduced every year. When considering element integration, the area occupied by device element isolation is increasing.

For element isolation in integrated circuits, buried diffusion layers are used in bipolar devices. This is for separation in the depth direction, and before epitaxial growth, pn impurities opposite to the high concentration epitaxial growth layer are diffused into the substrate. For lateral separation, after epitaxial growth, impurities that reach the substrate are diffused to create islands that form elements.

For MOS devices, silicon oxide (LOGO
3) is used. This creates a thick film of oxide between the regions where the devices are to be formed, thereby providing isolation between the devices.

In the case of impurity diffusion, it is necessary to sufficiently diffuse from the surface to the epitaxially grown film, and lateral diffusion inevitably occurs, expanding the element isolation region. LOCO
In the case of method 3, when selective oxidation is performed, an oxide film protrudes (so-called bird's beak) occurs under the oxidation prevention film (for example, silicon nitride), and the element formation area is reduced.

In order to cope with the expansion of these element isolation regions, it is necessary to include a margin region equivalent to that at the time of mask design, which hinders miniaturization. The effects of the formation of bird's beaks can be reduced by reducing the thickness of the oxide film used for element isolation, but thinning the oxide film is due to the potential difference caused when wiring such as power supply lines passes over it. Pn inversion may occur in the 81 portion under the oxide film, and element isolation may be broken. Therefore, the impurity concentration under the oxide film is increased to avoid inversion (channel stopper).

Another method being considered is to create a trench by etching the silicon substrate and bury a CVD oxide film in the trench to isolate the elements, but this method requires great stress on the wafer and technical difficulties. Since then, it has not been put into practical use.

Further, as the element isolation region becomes larger, stray capacitance generated in the element isolation region increases, reducing the operating speed of the device. In order to effectively isolate elements,
The periphery must be surrounded by a material and a shape that does not generate unnecessary parasitic capacitance components.

Therefore, if epitaxial growth can be selectively performed only in the element formation region on a silicon substrate, the problem of stray capacitance can be practically solved by considering the isolation between the silicon substrate and the lower part of the substrate.

When selectively epitaxially growing silicon on a silicon substrate using SiCl4 as a raw material, for example, the silicon surface is thermally oxidized, and then the oxide film in the area where silicon is to be selectively grown is removed by wet or dry etching. Epitaxial growth is performed on this substrate. A step mechanism is considered to be the reason for the selectivity between the silicon substrate surface and the oxide film surface. This is because on the exposed silicon surface there is a step of silicon that becomes a grown film when it grows from the vapor phase to the surface, so epitaxial growth progresses according to the following equation (3). However, although silicon adhesion from the gas phase occurs on the oxide film,
↑ (coefficient omitted) - (3) SiH4-4Si↓+2H2
↑ ...(3)'5to2+si -*Si
○ ↑ (Gas) ...(4) The reaction of equation (4) also occurs at the same time. Since the fine particles of silicon deposited on the oxide film are re-evaporated as SiO gas before they grow to a thermally stable size, no silicon is deposited on the oxide film.

Therefore, if there is a small amount of contamination on the oxide film, a specific part may become a growth step.

Selectivity is destroyed, so controlling selectivity is extremely difficult.

In order to actually maintain selectivity, the wafer surface must be cleaned at high temperature before epitaxial growth, or gaseous MC must be applied.
Etch the surface with I, etc. to improve cleanliness and maintain selectivity. Furthermore, since the temperature range in which the selectivity exists includes the reaction of formula (4), it becomes quite high. S IH4
Even the thermal decomposition system of 1100°C to 1200°C.

There are two problems with the characteristics of selectively grown silicon. One problem is the deterioration of electrical characteristics at the oxide film interface, and the other problem is the shape of the selectively grown epitaxial film.

For example, when performing selective epitaxial growth at 1300° C. for 15 minutes, the mask oxide film needs to have a thickness of at least 0.4 μm to withstand etching.

Therefore, since the side walls of the mask prevent the growth of the silicon facets toward the side, the interface between the mask side walls and the silicon is disturbed and becomes electrically unstable. When manufactured as a device, this portion acts as a current bus and causes leakage current. To avoid this, polysilicon is deposited on the sides of the mask oxide film to act as a buffer between the sides and the silicon interface, thereby reducing leakage current.

In addition, silane derivative gas is generated by cleaning the surface of the Si substrate with HCI, and the Si substrate and mask 510 are
The etching reaction of formula (4) occurs at the interface of 2. As a result, undercuts occur near the interface between the mask oxide film and the silicon at a stage before selective epitaxial growth, and stacking faults occur at the undercut positions during silicon epitaxial growth. The defects generated here multiply and grow as the grain grows. To prevent undercuts, lower the cleaning temperature or use a cleaning method other than heating (ultraviolet light, sputtering, etc.). In order to prevent the multiplication of stacking faults, it is necessary to lower the growth temperature and perform low-temperature selective growth. Although it is possible to lower the selective growth temperature by reducing the pressure, lowering the temperature also involves the problem of deterioration of the crystallinity of the epitaxially grown film itself, and sufficient electrical characteristics cannot be obtained.

When selective growth is performed, abnormal growth occurs in which the epitaxial layer bulges near the interface between the mask oxide film and silicon. Therefore, in the epitaxial layer, silicon/S
A phenomenon occurs in which the area near the boundary of i○2 becomes thicker than the center of the pattern. As a countermeasure, raising the growth temperature has been proposed.

However, raising the growth temperature is something that should be avoided due to the problems mentioned above.

The occurrence of facets also poses a problem. Facets occur because epitaxial growth changes from general two-dimensional growth to selective three-dimensional growth, and the dependence of silicon growth rate on plane orientation appears. -The growth rate of higher-order crystal planes becomes slower when fishing on a boat. When selective growth is performed on a (100) wafer, (110) or (11)
1) Surfaces appear as facets. These facets become larger as the growth thickness increases, and the size becomes too large to be ignored for use as a device.

If facets exist, a step will be created between the mask oxide film and the silicon epitaxial film, leading to disconnection of the wiring material used as the gate, and also causing surface irregularities, which will impede microfabrication.

[Problems to be Solved by the Invention] As a method of solving the above-mentioned problems at once, efforts are being made to considerably lower the epitaxial growth temperature. The above-mentioned problems can be solved by lowering the epitaxial growth temperature to 1000° C. or lower or even further. However, if the growth temperature is lowered, the above problems can be solved, but on the other hand, the crystallinity deteriorates, that is, the occurrence of stacking faults and the associated lifetime of minority carriers in the epitaxially grown film are reduced. New problems arise, such as reduction in carrier mobility in the grown film.

At present, a growth temperature of 1000° C. or lower is not practical because the crystallinity deteriorates. In addition, the growth rate of epitaxial growth is strongly influenced by the growth temperature, so the growth rate, which was about 0.5 to 5 μ/h at high temperatures, has changed to 100 μ/h.
If the temperature is below 0°C, the thickness will be on the order of several tens to hundreds of angstroms, making it impractical. In other words, when trying to grow at a low temperature, the lower limit of the growth temperature is determined by the quality of the growing film and the growth rate.

Further, the uniformity of the thickness of the grown film and the doping concentration are important conditions in the epitaxial growth of silicon. The uniformity of the grown film depends on the boundary layer, which is determined by the flow rate and flow direction of the source gas. When the flow rate becomes faster, the effect of decreasing concentration of raw material components in the gas phase outside the boundary layer becomes smaller, and the non-uniformity of the grown film becomes less. At that time, normal pressure or 0.1 atm
Under the above growth conditions, as the flow rate increases, there is a tendency for the surface structure of the grown film to deteriorate. An object of the present invention is to provide a method for growing a film and a chemical vapor deposition apparatus.

[Means for Solving the Problems] In order to achieve the above object, the first invention of the present application is a method for epitaxial growth of a silicon single crystal thin film. In other words, in this epitaxial growth method, a silicon substrate is held in a reaction tube evacuated to a high vacuum, and then heated to the epitaxial film growth temperature, source gas is blown into the gas line along with supporting hydrogen gas. The method comprises a step of supplying raw material gas onto the substrate surface at high speed and causing the reaction to occur by spraying onto the substrate surface using the pressure difference between the pressure and the pressure inside the reaction tube.

The second invention of the present application covers the silicon substrate installed at a predetermined location in the reaction tube except for the desired location with a mask member, and after holding the silicon substrate in the reaction tube which is evacuated to a high vacuum, epitaxial While heated to the film growth temperature,
Supplying the raw material gas onto the substrate surface at high speed by spraying the raw material gas onto the substrate surface using the pressure difference in the gas line and the pressure inside the reaction tube together with the hydrogen gas for spraying support; The gist is to selectively grow only in desired locations other than the mask member by causing the reaction to occur.

The third invention of the present application is that in a chemical vapor deposition apparatus (C to 'D apparatus), in addition to a carrier gas for transporting a raw material gas,
The gist is that a gas line for spraying support is provided to spray raw material gas onto the substrate.

[Operations] According to the first invention of the present application, a raw material gas is supplied onto the substrate surface at high speed and a reaction is carried out, so that a silicon film is epitaxially grown on the substrate at high speed.

Further, according to the second invention of the present application, silicon is not grown on the mask, and silicon is not grown on the mask by supplying raw material gas on the substrate surface at high speed to cause a reaction and causing epitaxial growth on the substrate at high speed. A silicon film is epitaxially grown only at desired locations.

Furthermore, according to the third invention of the present application, an apparatus is obtained that can grow an epitaxial single crystal thin film having good characteristics on a silicon substrate at a low temperature.

[Example] Embodiment of the third invention (device) Embodiments will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a CVD apparatus for carrying out the method of the present invention. In the figure, 1 is a reaction tube, 2 is a substrate,
3 is a bypass line, 4 is a feed through, 5 is a gate valve, 6 is a pressure adjustment valve, 7 is a baratron pressure gauge,
■1 to V9 are valves, MFC1 to MFC5 are mass flow controllers, RPI and RP2 are rotary pumps,
TMP is a turbo molecular pump, MBP is a mechanical booster pump, I2 is a substrate introduction mechanism, 11 is a substrate exchange mechanism and susceptor support mechanism, 13 is a thermocouple thermometer, 1
0 is an optical pyrometer, 9 is a susceptor, and 8 is a high frequency induction heating device.

The reaction tube 1 is evacuated by the pump through the feedthrough 4, and the raw material gas is a hydrogen compound of silicon or a silane compound such as a chloride derivative thereof, such as monosilane gas, and a hydrogen gas H2 for spraying support is used. In addition, mass flow controllers MFC1 and MF
C4, reaction tube l together through valves v1, v5, V7
supplied to

A substrate 21, for example, a Si substrate 2, is held at a predetermined position in the reaction tube 1 by a substrate exchange mechanism 12, and can be heated to a desired temperature by a high-frequency induction heating device 8, and the temperature of the susceptor 9 is controlled by the temperature of the susceptor 9 on which it is placed. The substrate surface temperature is simultaneously measured by a thermometer 13 using a thermocouple embedded in the substrate and an optical pyrometer 10.

When the raw material gas is supplied to the reaction tube together with the blowing support gas, the raw material gas is blown onto the surface of the substrate 2 at high speed due to the pressure difference between the gas line and the reaction tube 1.
The source gas reacts and a silicon epitaxial film grows on the substrate surface.

However, in this case, the total gas flow rate flowing into the reaction tube 1 during growth of the silicon single crystal thin film is set to a predetermined amount, the pressure in the reaction tube 1 during the thin film growth is kept at a predetermined static pressure, and the reaction tube 1 is kept at a predetermined static pressure. Static pressure in l (measured with baratron pressure gauge 7)
In order to independently adjust the gas flow rate sprayed onto the substrate 2, hydrogen gas for pressure and flow rate adjustment is flowed into the feedthrough 4 via the valve v9 and the bypass line 3.

The pressure adjustment valve 6 is adjusted to roughly set the static pressure and gas flow rate in the reaction tube 1, and under these conditions, the gas flow rate and static pressure flowing into the reaction tube 1 by the gas supply through the bypass line 3 are adjusted. It can be controlled independently of the pressure, and the raw material gas can be blown onto the surface of the substrate 2 under optimal conditions for single crystal film growth.

Note that the exchange and introduction of the substrate 2 are performed by the mechanisms 11 and 12, which are well known and have little relevance to the present invention, so a detailed explanation thereof will be omitted. Furthermore, the heating device and thermometer are not limited to those described above.

Furthermore, the above-mentioned spraying support hydrogen gas also has the function of instantly purging the raw material gas line with hydrogen gas when switching the raw material gas, so it has the effect of reliably eliminating residual gas when the supply of raw material gas is stopped. be.

Next, a manufacturing method of the present invention using the above-mentioned apparatus will be described, but the method of the present invention is not limited to using the above-mentioned apparatus, and any apparatus may be used.

Next, specific aspects of implementing the first invention will be described.

To prevent autodoping, from the reaction formula (2) above, H
Just remove CI. To remove HCI, a silane derivative that does not contain C1 is used. This is publicly known.

Another method is to remove the gas generated by the etching reaction from the substrate. To achieve this, the linear velocity inside the reaction tube can be significantly increased by increasing the gas flow rate and lowering the pressure.

Furthermore, to prevent outward diffusion and incorporation of impurities from outside the substrate, the growth temperature may be lowered to 900° C. or lower, or even as low as possible, but issues regarding crystallinity and growth rate must be resolved. Furthermore, by lowering the growth temperature in autodoping, the amount and rate of diffusion can be suppressed.

That is, in the method for producing a silicon epitaxial single crystal film of the present invention, a Si epitaxial single crystal thin film is produced on a predetermined substrate by chemical vapor deposition (CVD) using silane or a chloride derivative of silane as a raw material gas. In the method, the substrate is held in a reaction tube and heated in a hydrogen stream containing hydrogen chloride for a predetermined period of time to clean the surface of the substrate, and then the substrate is heated to a growth temperature of 81 epitaxial crystal. , evacuate the inside of the reaction tube,
By spraying the raw material gas onto the substrate surface using the pressure difference in the gas line and the pressure in the reaction tube together with hydrogen gas for spraying support, the raw material gas is supplied onto the substrate surface at high speed and reacted. , it is possible to perform epitaxial growth on the above substrate at high speed.

Therefore, unlike the conventional method, the raw material gas is simply heated at normal pressure (760
Torr) or a growth pressure of about 100 Torr is slowly supplied to a predetermined substrate in a reactor, and the raw material gas or decomposed products of the raw material drive a concentration difference on the substrate through a boundary layer formed between the substrate and the gas flow. Unlike methods in which the raw material gas is supplied as a force, a blowing support gas is required to spray the raw material gas onto the substrate at a sufficient linear velocity, and the spraying support gas is sprayed onto the substrate together with the raw material gas. It must be done. By doing so, it is possible to grow a single crystal film with excellent crystallinity on the substrate at a high growth rate without deteriorating the surface structure of the grown epitaxial film, despite the low temperature of 900° C. or lower. Furthermore, since a large flow rate of gas is blown at high speed under low pressure, the gas produced by the etching reaction is instantly removed to the exhaust system, significantly reducing autodoping. Furthermore, as a result of lowering the growth temperature, out-diffusion and impurity diffusion from outside the substrate are also significantly reduced.

In the case of conventional growth, as the growth temperature decreases, the growth rate rapidly decreases. In the case of this growth method, 90
Even at about 0'C, if an appropriate amount of raw material is contained in the gas blown, a growth rate close to that of high-temperature growth can be obtained.

In addition, in order to make the flow rate of the raw material gas sprayed into the reaction tube obtained by the spraying support gas (this is equivalent to the linear velocity) the optimum condition for epitaxial growth, a bypass for pressure and flow rate adjustment is installed in parallel with the reaction tube. By installing a gas line and changing the flow rate of the gas flowing into the reaction tube and the gas flowing through the bypass gas line, the amount of gas flowing into the reaction tube and the pressure inside the reaction tube can be independently changed to obtain the optimum blowing flow rate. An epitaxial film with excellent properties can be produced.

Embodiments of the First Invention Example 1 (Example using SiH4) A Si (100) substrate on which an N+ buried layer was formed using antimony as an impurity was heated to 1 torr or less, for example, 1.
After performing high-temperature cleaning including surface etching due to the action of hydrogen chloride in a hydrogen flow containing hydrogen chloride at a flow rate of about 0 torr 11000 to 3000 sec at a substrate temperature of about 900°C for 5 minutes or more, the substrate surface temperature was adjusted to the silicone epitaxial growth temperature of 700 to 800°C. At this temperature, a $1 single crystal film of a predetermined thickness is grown directly on the Si substrate using silane and hydrogen gas or argon gas for spraying support at a static pressure of 1-10 torr. Ta.

At this time, in order to obtain a single-crystalline thin film that is flat with no protrusions or bits on the surface, has few stacking faults, and has excellent crystallization, the above raw material gas, which is poured into the reaction tube 1, is mixed with hydrogen gas for spraying support. It is extremely important to use the pressure difference in the gas line and the reaction tube to forcibly spray the gas onto the substrate 81, and the total amount of gas for approximately 2000 to 4000 seconds is poured from the top of the reaction tube 1 onto the substrate 81. is. As in the conventional epitaxial growth method, the carrier gas is slowly flowed under high pressure, and the silane raw materials or their decomposition products diffuse through the carrier gas boundary layer that naturally forms on the 81 substrate, resulting in silicon epitaxial growth on the 81 substrate. In the method in which the film is produced, a good silicon epitaxial film cannot be grown at the temperature of the present method. Therefore, it is preferable to independently control the total amount of gas flowing into the reaction tube and the static pressure inside the reaction tube so that the gas flowing into the reaction tube has an appropriate linear velocity.

(Specific Growth Example 1) The growth temperature profile is shown in FIG. The Si substrate used has a diameter of 3 inches (111). The conditions for cleaning the Si substrate are a substrate temperature of 900°C and a static pressure of 0.4 torr.
, in a hydrogen gas flow containing hydrogen chloride with a flow rate of 1500 sec 1
It was set to 0 minutes. Thereafter, the temperature was lowered, and the growth temperature of the silicon epitaxial film was about 700°C. Silane gas diluted to 1% based on hydrogen gas and hydrogen gas for spraying support were flowed into the dark reaction tube for silicon epitaxial film growth for 2200 seconds and forcedly sprayed onto the Si substrate.

Hydrogen was flowed at 1000 sec through the bypass line 3, and the static pressure was set to 3 torr as measured by a baratron pressure gauge 7 provided in the field through 4 in the reaction tube 1. The growth rate changes by changing the silane to hydrogen gas ratio, but the growth rate is 0.
．． There was not much difference in film quality under conditions of about 1 to 1 μ/win.

When the surface of the epitaxial film grown to 4μ was observed using a Nomarski microscope, no surface irregularities or surface defects such as bits or slips were observed on the surface.

Conventional WRIGHT etching was performed to observe stacking faults. The number of stacking faults found was 0.5/
d or less.

The mobility of the silicon epitaxial film produced by this method was evaluated by conventional Hall measurement.

Boron (B) doped low resistance p-type substrate (specific resistance 1
A silicon epitaxial film doped with phosphorus and having a specific resistance of 4 to 5 ohms was fabricated by the method of the present invention. The film thickness is 4μ. The impurity distribution of the epitaxially grown layer was evaluated using a two-end needle spread resistance measuring device.

At this time, the outward diffusion region from the substrate surface was 1 μm or less.

The electron mobility of the silicon epitaxial film due to the Hall effect was 1750 crd/v-sec. This value indicates that the film has sufficient characteristics as an epitaxial film even though the growth temperature is lower than that of conventional films.

(Specific Growth Example 2) The 81 substrate used has a diameter of 3 inches (111). S
The conditions for cleaning the i-substrate were a substrate temperature of 900° C., a static pressure of 0.4 torr, and a flow rate of 1500 sec in a hydrogen stream containing hydrogen chloride for 10 minutes. Thereafter, the temperature was lowered, and the growth temperature of the silicon epitaxial film was approximately 830°C. During silicon epitaxial film growth, the inside of the reaction tube is filled with hydrogen gas at zero.
Dichlorosilane gas (SiHz Cl2) diluted to 5%
), 2500 sec including hydrogen gas for spray support
The liquid was forced to flow onto the Si substrate. Hydrogen was flowed through the bypass line 3 for 1000 sec+, and the static pressure was set to 3 torr as measured by a baratron pressure gauge 7 provided in the field through 4 in the reaction tube 1. The growth rate changes by changing the ratio of dichlorosilane to hydrogen gas, but the growth rate is 0.
．． There was no significant difference in film quality under conditions of about 1 to 1 μ/min.

The surface of the epitaxial film grown to 4 μm was observed using a Nomarski microscope, but no surface defects such as surface irregularities, bits, or slips were observed. I did etching. The number of stacking faults found was 0.5/d or less.

The mobility of the silicon epitaxial film produced by this method was evaluated by conventional Hall measurement.

Low resistance p-type substrate doped with boron (B) (specific resistance 18
A silicon epitaxial film doped with phosphorus and having a specific resistance of 4 to 5 ohms was fabricated using the method of the present invention. Belly thickness is 4μ. The impurity distribution of the epitaxially grown layer was evaluated using a two-end needle spread resistance measuring device. The outdiffusion area was less than 1 μm.

The electron mobility of the silicon epitaxial film due to the Hall effect was 1760 d/v-sec. This value indicates that although the growth temperature is lower than conventional ones, almost no autodoping occurs due to substrate etching, and that the film has sufficient characteristics as an epitaxial film.

From the above, it is obvious that the method of the present invention is applicable not only to dichlorosilane but also to silane derivatives such as trichlorosilane and tetrachlorosilane.

Next, a specific embodiment of the second invention will be described.

In order to solve the problem of the second invention, silicon grows on the silicon oxide film under conditions that do not cause an etching reaction of the silicon oxide film with silicon in the boundary region between the mask oxide film and the silicon and on the mask surface. It is only necessary to find conditions under which epitaxial growth of silicon occurs only on the silicon surface. In other words, it is sufficient to cause reaction formula (1) only on the silicon substrate surface.

That is, in a method for manufacturing a silicon epitaxial single crystal film, a predetermined amount of Si epitaxial single crystal thin film is selectively grown on a predetermined substrate by chemical vapor deposition (CVD) using silane or a chloride derivative of silane as a raw material gas. A silicon wafer with a surface orientation of 5 is
The film is oxidized to a thickness of 102 mm, then patterned into a desired shape by photolithography, and windows are opened at desired locations by an appropriate etching method. Next, the substrate was placed in a reaction tube and heated in a hydrogen stream containing hydrogen chloride for a predetermined period of time to clean the surface of the substrate.
i While heated to the epitaxial single crystal growth temperature,
The inside of the reaction tube is evacuated, and the raw material gas is sprayed onto the substrate surface using the pressure difference between the gas line and the reaction tube together with the hydrogen gas for spraying support, thereby spraying the raw material onto the substrate surface at high speed. By supplying a gas, causing a reaction, and growing epitaxially at high speed on the above substrate, 5i
Silicon does not grow on the 02 mask, and a silicon film grows epitaxially only in the window-opened areas.

Example 2 (example using SiH2) A silicon wafer with a predetermined surface orientation is heated to a predetermined 5iO)
The film was oxidized to a thickness of 4.0 mm, then patterned into a desired shape by photolithography, and windows were opened at desired locations by dry etching. Subsequently, the above substrate was set in the reaction tube. After that, the substrate temperature was 100°C in a hydrogen flow containing a small amount of hydrogen chloride at 1 torr or less and several thousand seconds.
After high-temperature cleaning including surface etching by the action of hydrogen chloride at 0°C or higher for 5 minutes or more, the substrate surface temperature was lowered to the silicon epitaxial growth temperature of 700 to 950°C, and the growth pressure was set to 1 to 8 torr in static pressure. 81 single crystal film of a given thickness using silane at temperature
It was selectively grown on the i-substrate.

At this time, in order to obtain a selectively grown epitaxial film that does not lose selectivity despite the low temperature, has good crystallinity, and has a flat surface without facet growth or abnormal growth around the pattern. It is extremely important to forcibly spray the raw material gas flowing into the reaction tube 1 onto the substrate using the pressure difference between the gas line and the reaction tube together with the hydrogen gas for spraying support. 1000
~4000sec total gas amount from the top of reaction tube 1
It was poured onto 1 substrate 2. In this case, as in the conventional epitaxial growth method reported in the literature, the carrier gas is slowly flowed under high pressure, and the silane raw materials or their In the method in which a silicon epitaxial film is formed on the 81 substrate by diffusion of decomposed products, a good selectively grown silicon epitaxial film cannot be grown at the temperature of this method. Therefore, it is preferable to independently control the total amount of gas flowing into the reaction tube and the static pressure inside the reaction tube so that the gas flowing into the reaction tube has an appropriate linear velocity.

(Specific Growth Example) The growth temperature profile is shown in Figure 2. The 81 substrate used was 3 inches (100) in diameter. After forming a 0.5 μm oxide film using a steam oxidation method, a required pattern was formed by photolithography. Thereafter, a window in the oxide film was opened using a plasma dry etching method. After removing the resist used in photolithography, the substrate was placed in a reactor. The cleaning conditions for the No. 81 substrate were as follows: substrate temperature: 1,000° C., static pressure: 0.4 t, arr, and 15 minutes in a hydrogen stream containing 1% hydrogen chloride at a flow rate of 1,500 sec.

Thereafter, the temperature was lowered, and the growth temperature of the silicon epitaxial film was about 700°C. During silicon epitaxial layer growth, the reaction tube contains 220 ml of hydrogen gas, including monosilane gas diluted to 1% and hydrogen gas for spraying support.
It was forcibly sprayed onto the 81 substrate with a flow of 0 seconds. 1000 sec of hydrogen was flowed into the bypass line 3, and a baratron pressure gauge 7 installed in the field through 4 inside the reaction tube 1
The static pressure measured was 3 torr. The growth rate changes by changing the silane to hydrogen gas ratio, but the growth rate is 0.
There was not much difference in film quality under conditions of about 1 to 1 μ/win.

At this time, no silicon growth was observed on the oxide film, confirming that selective growth was occurring.

The cross-sectional shape of the selective epitaxially grown silicon wafer was observed using a scanning electron microscope. No abnormal growth was observed in the facet shape or pattern periphery, and the mask oxide film and the surface of the selective epitaxial growth were flat.

A conventional WRr GHT etch was performed to observe stacking faults. No stacking faults were observed in the center of the pattern, which may be caused by undercuts.

The electron mobility of the selectively grown epitaxial film portion was measured. A film doped with phosphorus at 10"/cm was used. The electron mobility at room temperature was 1750 CIIl/V-see, and a film close to that of a bulk epitaxial film was obtained.

Example 3 (Example using Sl.H2Cl2) A silicon wafer with a predetermined surface orientation is oxidized to a predetermined Si○2 film thickness, and then the desired shape is patterned by photolithography, and the desired shape is formed by dry etching. A window was opened at the location. Subsequently, the above substrate was set in the reaction tube. After that, in a hydrogen flow containing a small amount of hydrogen chloride at 1 torr or less and several thousand seconds, the substrate temperature was 1000°C or more for 5 minutes or more, and after high-temperature cleaning including surface etching due to the action of hydrogen chloride, the substrate surface temperature was lowered to 8000-950°C.
The silicon epitaxial growth temperature was lowered to .degree. C., the growth pressure was statically set to 1 to 8 torr, and an 81 single crystal film of a predetermined thickness was selectively grown on the 81 substrate using silane at this temperature.

The general flow of each of the above steps is the same as that shown in FIG.

At this time, in order to obtain a selectively grown epitaxial film that does not lose selectivity despite the low temperature, has good crystallinity, and has a flat surface without facet growth or abnormal growth around the pattern. It is extremely important to forcibly spray the raw material gas flowing into the reaction tube 1 onto the substrate using the pressure difference between the gas line and the reaction tube together with the hydrogen gas for spraying support. 1000
S from the top of reaction tube 1 with a total gas volume of ~4000 sec
It was poured into i-board 2. As in conventional epitaxial growth methods reported in the literature, the carrier gas is slowly flowed under high pressure, and the silane raw materials or their decomposition products diffuse through the carrier gas boundary layer that naturally forms on the Si substrate. In a method in which a silicon epitaxial film is produced on a Si substrate using a silicon substrate, a good selectively grown silicon epitaxial film cannot be grown at the temperature of this method.

Therefore, it is preferable to independently control the total amount of gas flowing into the reaction tube and the static pressure inside the reaction tube so that the gas flowing into the reaction tube has an appropriate linear velocity.

(Specific growth example) The 81 substrate used has a diameter of 3 inches (100). After forming a 0.5μm oxide film using steam oxidation method,
A required pattern was formed by photolithography. Thereafter, a window in the oxide film was opened using a plasma dry etching method. After removing the resist used in photolithography, the substrate was set in a reagator. The conditions for cleaning the 81 board are: board temperature 1000℃, static pressure 0.4torr, 1%
In a hydrogen flow containing hydrogen chloride with a flow rate of 150Q sccm 1
It was set as 5 minutes. Thereafter, the temperature was lowered, and the growth temperature of the silicon epitaxial film was about 800°C. During the growth of the silicon epitaxial layer, diglolsilane gas diluted to 1% based on hydrogen gas and hydrogen gas for spraying support were flowed in the reaction tube for 2200 seconds and forcedly sprayed onto the Si substrate. Hydrogen 1000se in bypass line 3
cm, and the static pressure was 3 torr as measured by a baratron pressure gauge 7 provided in the field through 4 in the reaction tube 1. Although the growth rate changes when the ratio of silane to hydrogen gas is changed, there is no significant difference in film quality under conditions where the growth rate is approximately 0.1 to 1 μ/min.

At this time, no silicon growth was observed on the oxide film, confirming that selective growth was occurring.

The cross-sectional shape of the selective epitaxially grown silicon wafer was observed using a scanning electron microscope. No abnormal growth was observed in the facet shape or pattern periphery, and the surfaces of the mass polyoxide film and the selective epitaxial growth were flat.

Conventional WRI GHT etching was performed to observe stacking faults. No stacking faults were observed in the center of the pattern, which may be caused by undercuts.

The electron mobility of the selectively grown epitaxial film portion was measured. Phosphorus 10 “” / cn? A doped version was used. Electron mobility at room temperature is 1750 cm/V −s
ec, and a film close to a bulk epitaxial film was obtained.

[Effects of the Invention] As described above, according to the present invention, a high-quality silicon epitaxial film is formed on a silicon substrate at a temperature far lower than the temperature at which impurity diffusion from outside the substrate or outward diffusion from the substrate occurs. It can be manufactured at high speed, and autodoping is almost completely suppressed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a CVD apparatus for carrying out the method of the present invention, and FIG. 2 is a diagram showing an example of a growth temperature profile according to the method of the present invention. 1...Reaction tube, 2...Substrate, 3...Bypass line, 4...
...Field through, 5...Gate valve, 6...Pressure adjustment valve, 7...
...Baratron pressure gauge, 8...High frequency induction heating device, 9...Susceptor, 10
......Optical pyrometer, 11...
...... Board exchange mechanism and susceptor support mechanism, 13
......Thermocouple thermometer. Patent Applicant Clarion Co., Ltd. Agent Patent Attorney Nagai 1) Takeshi Part 3 Figure 1

Claims (8)

[Claims] (1) After holding the silicon substrate in a reaction tube evacuated to high vacuum, and heating it to the epitaxial film growth temperature, source gas is sprayed together with hydrogen gas for support, and the pressure inside the gas line and the inside of the reaction tube are adjusted. A method for epitaxial growth of a silicon single crystal thin film, comprising a step of supplying a raw material gas onto the surface of the substrate at high speed by spraying it onto the surface of the substrate using a pressure difference, and causing a reaction. (2) The method for epitaxial growth of a silicon single crystal thin film according to claim (1), wherein the source gas is silane (SiH_4). (3) The raw material gas is SiH_2Cl_2, Si
The method for epitaxial growth of a silicon single crystal thin film according to claim (1), characterized in that HCl_3 or SiCl_4 is used. (4) Cover the silicon substrate installed at a predetermined location in the reaction tube with a mask member, hold the silicon substrate in the reaction tube that is evacuated to high vacuum, and then heat to the epitaxial film growth temperature. In this state, the raw material gas is sprayed onto the substrate surface using the pressure difference between the gas line and the reaction tube together with the hydrogen gas for spraying support, thereby spraying the raw material gas onto the substrate surface at high speed. An epitaxial growth method characterized by selectively growing only at desired locations other than a mask member by supplying and reacting. (5) Claim No. 4, characterized in that the mask member is made of silicon oxide, silicon nitride, or a laminated material thereof.
) Growth method as described in section. (6) The raw material gas is monosilane (SiH_4), dichlorosilane (SiH_2Cl_2), trichlorosilane (S
iHCl_3) or tetrachlorosilane (SiCl
_4) Claim No. (4)
Growth method described in section. (7) A chemical vapor deposition apparatus (CVD apparatus) characterized in that, in addition to a carrier gas for transporting the raw material gas, a gas line for spraying support for spraying the raw material gas onto the substrate is provided. Phase growth device. (8) In claim (7), pressure and flow rate adjustment for the purpose of flow rate and pressure adjustment in order to bring the linear velocity of the raw material gas and blowing support gas flowing into the reaction tube into optimal epitaxial conditions. A chemical vapor deposition device characterized by a line installed in parallel with a reaction tube.