JPH01313395A - Method for growing silicon in vapor phase - Google Patents

Abstract

PURPOSE:To rapidly deposit silicon on a substrate even in a low-temp. region by using SiCl4 and SiH2Cl2 as the raw gas, and forming silicon on the substrate while blowing atomic H against the substrate. CONSTITUTION:The substrate 19 for growing silicon P<->(100), for example, is placed in a furnace 11, the atmosphere in the furnace is replaced by gaseous nitrogen, and then the substrate is baked in an H2 atmosphere. Gaseous H2 is introduced while introducing the silicon chloride or silicon hydrochloride (e.g., SiH2Cl2) as the raw material through a preheating cell 15 at about 850 deg.C. The H atom obtained by dissociating hydrogen molecule with a cell 16 is simultaneously blown against the substrate 19 heated to about 800 deg.C by a substrate preheating heater 14 to grow silicon on the substrate 19. Dissociation of hydrogen molecule by plasma or by light irradiation can be utilized in the cell 16 for dissociating hydrogen molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor growth method, and more particularly to a silicon vapor phase growth method performed at low temperatures.

(Prior Art) Chemical vapor deposition is conventionally known as an epitaxial growth technique for forming silicon crystals using dichlorosilane (Sjf12CI2) or the like as a raw material. For example, in silicon crystal growth by chemical vapor deposition using dichlorosilane as a raw material gas, 5
A mixture of jH2C12 and hydrogen as a carrier gas at a certain flow rate ratio is simultaneously introduced into the growth apparatus, and a film is deposited on the silicon substrate by heating the entire reactor or heating only the substrate part. Ta. The reason for heating the entire furnace or only the substrate in this way is to decompose the raw material gas necessary for depositing a film and to cause a surface reaction on the substrate surface.

(Problems to be Solved by the Invention) However, this heating temperature poses a problem in normal silicon epitaxial growth. That is, the deposition of an epitaxial film usually requires a temperature of too much or more. Such high growth temperatures pose problems in utilizing this process. For example, impurity diffusion occurs due to high temperatures, making it impossible to obtain the steep impurity profile currently required. Therefore, in order to realize such a steep profile, a reduction in the growth temperature is required. However, there is a problem in that simply lowering the temperature does not allow a practically necessary growth rate to be obtained. Even if the supply amount of source gas is increased in order to increase the growth rate, the growth rate will not increase in such a low temperature and slow growth rate region. In other words, the growth rate becomes saturated at a certain growth rate. This is because the growth rate is rate-limited by a so-called surface reaction. Therefore, in order to increase the growth rate in a low temperature range, it depends on how quickly a surface reaction can occur to remove chlorine atoms present on the surface. The present invention eliminates these conventional drawbacks and provides a vapor phase growth method that promotes surface reactions at low temperatures and can increase growth rates.

(Means for Solving the Problems) According to the present invention, there is obtained a semiconductor vapor phase growth method characterized in that a source gas and atomic hydrogen are blown onto a substrate.

(Operation) According to the present invention, atomic hydrogen is supplied to the surface of the substrate into which the source gas has been absorbed. Since this atomic hydrogen is chemically active, it acts on the source gas to remove the chlorine source r, promoting the growth of silicon on the substrate. For example, if the substrate temperature is 1
The effect of this atomic hydrogen makes it possible to grow silicon at a practical growth rate even at low temperatures of 0,000° C. or less.

(Example) The crystal growth method of the present invention will be explained using FIG. 1st
The figure is a schematic diagram of the apparatus used when depositing silicon on a substrate in this method. This device consists of a reactor (11)
, a pump (12) to reduce the pressure inside the furnace, a susceptor (13) that supports the substrate, a heater (Dungesten wire sealed in quartz glass) (14) to heat the substrate, and preheating of 5iH2C12. A cell (15) for atomic dissociation of hydrogen molecules, a cell (15) for atomic dissociation of hydrogen molecules
8), and a gas flow rate control section (controls the flow meter by using a mass flow controller) (17). The substrate temperature was measured using a pyrometer (18) through a window provided in the furnace. The measured results are fed as a feedbank to the controller for the heater for heating the substrate, so that the substrate temperature can be maintained constant.

This is a preheating cell for 5IH2CI2, but because the pressure during growth is low, sufficient decomposition of 5IR2C1□ does not occur and the generation efficiency of reactive species decreases, so the raw material gas is heated in advance. This is to ensure that sufficient decomposition occurs. Also, hydrogen molecules are dissociated to produce atomic hydrogen,
This time, hydrogen atoms were obtained by plasma discharge 27 using a microwave power source 24 as shown in FIG. H2 gas is introduced into the discharge tube 25 from the hydrogen introduction tube 28. A 2.45GH2 microwave is used to generate hydrogen plasma 2.
7 was generated. As a substrate for growth, silicon P-
(100) was used. After the usual Branson cleaning, it was placed in the reactor. After replacing the air inside the furnace with nitrogen gas at normal pressure for 10 minutes, the pump was started to once create a high vacuum inside the furnace, and then hydrogen gas was flowed into the inside of the furnace. Prior to growth, in order to remove the oxide film existing on the surface of the silicon substrate, it was
r) Baking was performed for 5 minutes at a substrate temperature of 950°C.

After that, the flow rate of 5HI2C12 is 5 to 30 cc.
/win 1 50cc/+Ins as a hydrogen gas flowmeter
Growth pressure 0.01 Torr, substrate temperature 800°C, 5IH
Growth was performed at a temperature of 850°C in a 2CI2 preheating cell. Figure 3 shows the case using atomic hydrogen and the case of normal growth (growth pressure 20 Torr1 hydrogen flow (j1500
cc/win, 5iH2c+2 flow rate 5-30 cc
/win, substrate temperature 800° C.). It can be seen that despite the same substrate temperature, the growth rate increases by decomposing hydrogen gas into atoms. In addition, in the present invention, the substrate temperature is 700°C.
Above that, a growth rate sufficient for practical use was obtained.

This time, we used a hydrogen molecule decomposition cell that utilizes plasma, but hydrogen molecules may also be decomposed by light irradiation or the like. Alternatively, a metal heated to a high temperature may be dissociated by colliding with hydrogen molecules. In addition, this time, we showed the experimental results using 5l) I2C1□ as the raw material gas, but other raw material gases whose rate is determined by the final extraction of chlorine atoms present on the substrate surface by atomic hydrogen as a surface reaction may also be used. , for example 5IHICI3.5IC1
The same effect can be obtained when silicon chloride chloride such as No. 4 or a silicon chloride-based gas is used. Further, the Si to be grown may be not only crystalline but also polycrystalline or amorphous.

(Effects of the Invention) As described above in detail, according to the method of the present invention, by spraying atomic hydrogen onto the substrate surface during growth, it is possible to accelerate the surface reaction, and However, silicon can be deposited onto the substrate at a fast growth rate.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the silicon growth apparatus used in the example.
FIG. 2 is a diagram showing a hydrogen molecule decomposition cell, and FIG. 3 is a diagram showing growth rates obtained in Examples. In the figure, 11 reactor, 12 pump, 13 susceptor, 14 substrate heating heater, 15 5in2c
12 Cell for preheating, 16 Cell for dissociating hydrogen molecules, 17 Gas flow rate controller, 18 Pyrometer, 19 Substrate, 20H2 line, 21 5il12C
12 lines, 22 short-circuit plunger matching device, 23 cooling water, 24 micro power source, 25 discharge tube, 26 waveguide, 27 plasma, 28 hydrogen introduction tube.

Claims (1)

[Claims] A silicon vapor phase growth method using silicon chloride or silicon hydrogen chloride as a raw material gas, characterized in that silicon is formed on the substrate while blowing atomic hydrogen onto the substrate surface. .