JPH01313394A - Method for growing silicon - Google Patents

Abstract

PURPOSE:To rapidly deposit silicon on a substrate even in a low-temp. region by using SiCl4 or SiH2Cl2 as the raw gas, and growing silicon on the substrate while blowing H2 molecule provided with heat energy against the substrate. CONSTITUTION:The substrate 19 for growing silicon P<->(100), for example, is placed in a furnace 11, then the atmosphere in the furnace is replaced by gaseous N2, and the substrate 19 is baked in an H2 atmosphere. The SiCl4 or SiH2Cl2 (e.g., SiH2Cl2) as the raw gas is introduced through a preheating cell 15. The H2 molecule is heated to about 1000 deg.C by a cell 16 for heating the H2 molecule, provided with heat energy thereby, and blown against the substrate 19 heated at about 800 deg.C by a substrate heater 14 to grow silicon on the substrate 19.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor growing method, and more particularly to a silicon vapor phase growth method that allows a practical growth rate to be obtained at a low substrate temperature.

(Prior Art) Chemical vapor deposition is conventionally known as an epitaxial growth technique for forming silicon crystals using dichlorosilane (SiH2C12) or the like as a raw material. For example, in silicon crystal growth by chemical vapor deposition using dichlorosilane as a raw material gas, 5i
A mixture of H2C1° and carrier gas hydrogen at a certain flow rate 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. was. Heating the entire furnace or only the substrate in this way is necessary to decompose the raw material gas necessary for depositing the 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, deposition of an epitaxial film usually requires a temperature of 1000° or higher. 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 if the temperature is lowered, the growth rate required for practical purposes cannot 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 1. 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 in which hydrogen molecules extract chlorine atoms present on the substrate surface occurs. The present invention eliminates these conventional drawbacks and provides a crystal growth method capable of promoting surface reactions at low temperatures and obtaining a sufficient growth rate.

(Means for Solving the Problems) The present invention is characterized in that hydrogen molecules given particular thermal energy are blown onto the substrate when silicon chloride or hydrogenated silicon chloride-based raw material gas is supplied to the substrate.

(Function) When hydrogen molecules given thermal energy are blown onto the substrate during the growth of Sl, these hydrogen molecules can extract chlorine atoms from the source gas adsorbed on the substrate surface. As a result, SI is deposited. At this time, the substrate temperature is 1000
Even if the temperature is lower than .degree. C., if thermal energy is given to hydrogen molecules, Si can be deposited at a practical growth rate.

(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) to support the substrate, a heater to heat the substrate (Dungesten wire sealed in quartz glass) (14), preheating of 5iH2CI2 cell for heating hydrogen molecules (15), cell for heating hydrogen molecules (
16), a gas flow rate control section (controls the flow rate 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 back to the substrate heating heater control device to maintain the substrate temperature constant.

Here, the 5iH2C1° preheating cell is used, but if the decomposition of 5IH2C1° does not occur sufficiently due to the low pressure during growth, and the generation efficiency of reactive species decreases, preheating is sufficient. This is to allow decomposition to occur.

Silicon P''' (+00) was used as the substrate for growth. After the usual Branson cleaning, it was placed in the reactor. After replacing the air inside the reactor with nitrogen gas at normal pressure for 10 minutes, the pump After starting up the furnace and creating a high vacuum inside the furnace, hydrogen gas was flowed into the furnace.Prior to the growth, in order to remove the oxide film existing on the surface of the silicon substrate, a pressure crab inside the furnace torr) and a substrate temperature of 950°C for 5 minutes.

After that, the flow rate of 5IH2C12 is 5 to 30 cc.
/sin% Hydrogen gas flow rate is 50 cc/win
1 growth pressure 0. Growth was performed under the conditions of ITorr, substrate temperature of 800°C, hydrogen gas heating cell temperature of 1000°C, and SiH2C12 preheating cell temperature of 850°C. Second
The figure shows the growth rate when hydrogen gas is heated and when it is not heated. It can be seen that the growth rate increases by heating the hydrogen gas, despite the same substrate temperature. Note that a practical growth rate was obtained when the substrate temperature was 700° C. or higher. Also, the heating temperature of hydrogen is 1000
Even if the temperature was lower than °C, the heating effect of hydrogen was observed as long as the temperature was higher than the substrate temperature.

In this case, a heating cell was used to heat the hydrogen molecules, but the hydrogen molecules may also be heated by exciting the hydrogen molecules with light irradiation or the like and converting that energy into thermal energy. In addition, this time, we showed the experimental results using 5IH2C12 as a raw material gas, but 5IHIC13 and 5IC14 are raw material gases whose rate is determined by the final extraction of chlorine atoms present on the substrate surface by hydrogen molecules as a surface reaction.
The same effect can be obtained when silicon hydrogen chloride or silicon chloride-based raw materials are used.

(Effects of the Invention) As described above in detail, according to the method of the present invention, surface reactions can be promoted by spraying hydrogen molecules to which thermal energy has been applied during growth onto the substrate. Silicon can be deposited on a substrate at a high growth rate even at a low substrate temperature of 1000° C. or less.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a silicon growth apparatus used in an example of the present invention, and FIG. 2 is a diagram showing the growth rate of silicon by the growth method of the present invention. In the figure, 11 reactor, 12 pump, 13 susceptor, 14 substrate heating heater, 15 5iH2
These are a cell for preheating C1°, 16 a cell for heating hydrogen molecules, 17 a gas flow control section, 18 a pyrometer, and 19 a substrate. Agent Patent Law Inner Thickness B1ff Figure 1

Claims (1)

[Claims] A silicon growth method using silicon chloride or hydrogenated silicon chloride raw material gas, which is characterized by growing silicon on a substrate while blowing hydrogen molecules given thermal energy onto the substrate.