JPH0360028A - Doping n-type impurity - Google Patents

Abstract

PURPOSE:To improve doping efficiency by carrying out vapor or solid doping using trimethylphosphine having low combination dissociation energy as N-type impurity. CONSTITUTION:TMP(trimethylphosphine) is introduced through a conductance valve 3 while a reaction chamber 1 is exhausted by an exhaust means 2. An oxide silicon film is provided to a surface of glass substrate on a substrate mount base 4, and a semiconductor material 5 whereon a polycrystalline silicon film is deposited is placed thereon. A laser beam 6 of high energy is irradiated to a surface of the semiconductor material 5. A place whereon the laser beam 6 of the semiconductor material 5 is irradiated is doped with phosphorus which is dissociated from TMP.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention provides n! :1 Concerning a method for doping impurities.

(b) Conventional technology nl! for semiconductor bulk materials and semiconductor thin films! :! Various doping methods have been proposed for doping with impurities, but the laser doping method, in which semiconductor materials are directly doped from n-type impurities in a vapor phase using a laser beam, is a low-temperature and simple process, and is suitable for shallow PN. It is attracting attention because of its ability to form bonds. The n-type impurity used for laser doping is PH
, , Pct, , POCIs, etc. are frequently used.

(c) Problems to be solved by the invention On the other hand, rlJ! ! To act as an impurity of I, the above-mentioned PH, , PCl, , POCI.

It is necessary to separate phosphorus from phosphorus compounds such as

However, the bond dissociation energy required to separate phosphorus from these phosphorus compounds is, for example, in the case of I) II,
It is generally high at 343 KJ/mol, and the dissociation efficiency is low.

(d) Means for Solving the Problems The present invention has been made in view of the above problems, and uses trimethylphosphine [p(CH,)s, hereinafter TMP], which has a low bond dissociation energy as an n-type impurity. [abbreviated as]] is used to perform gas phase or in-phase doping.

(E) Effect According to the present invention, phosphorus is separated from a phosphorus compound with low energy, and doping efficiency can be improved.

(v) Example diagram is a conceptual diagram showing the configuration when implementing the doping method of the present invention, in which ] is a reaction chamber associated with evacuation means 2, and furthermore, this reaction chamber 1 is filled with TMP or carrier. @4 is a substrate stand placed in the reaction chamber 1, on which a conductance valve 3 for introducing gas, etc. is attached;
A conductive material 5 doped with n'ff impurities is deposited. Reference numeral 6 denotes a laser beam that is irradiated onto the surface of the semiconductor material 5, which is focused by a light converging means 7 placed outside the reaction chamber 1, and is supplied through a light transmission window 8.

First, a more detailed explanation will be given by citing specific values when the method of the present invention is adopted for vapor phase doping.

The reaction chamber I is evacuated by the exhaust means 2, and at the same time TMP is introduced through the conductance valve 3, and the partial pressure in the reaction chamber 1 is set to 10 Torr and 50 SCCM. On the substrate a'Ii stand 4, there are two
A silicon oxide film with a thickness of 1,000 people is provided, and a film of 15
A semiconductor material 5 having a polycrystalline silicon film deposited thereon is placed. Note that the temperature of this semiconductor material 5 is 25°C. Now, if we consider the bond dissociation energy of TMP, its chain is 287 KJ/mol, which is considerably lower than that of PH.

As the laser beam 6 irradiated onto the surface of the semiconductor material 5, an excimer laser with a wave of Iz193nI11 is used,
The energy density on the surface of the semiconductor material 5 is 300/
The score was C- and the number of shots was 10.

As a result of the doping treatment under such conditions, the portions of the semiconductor material 5 irradiated with the laser beam 6 are doped with phosphorus separated from the TMP, and the impurity concentration is 10''/c+.
The n-type of a' is shown.

Next, the case of solid phase doping will be explained.

In the reaction chamber 1, TMP has a partial pressure of 0, 5 Torr, 5 S.
Introduced under CCM conditions, an ultraviolet excimer laser beam 6 with a wavelength of 193 na+ is introduced under CCM conditions, with the semiconductor material 5 kept at 25° C., with an energy intensity of 80 mJ/cva'', a laser pulse repetition frequency of 5011z, and an irradiation time of 1 minute. As a result, a phosphorus-based thin film of about 1,000 μm is deposited on the surface of the semiconductor material 5. After the growth of this phosphorus-based thin film, the reaction chamber l
After evacuating the TMP inside, a solid phase doping process is performed. For this purpose, the degree of vacuum in the reaction chamber 1 is set to I
Torr, the substrate temperature was set at 25° C., and an excimer laser beam 6 with an energy intensity of 350 mJ/cm was irradiated with lO shots onto the surface of the P conductor material 5. As a result of processing under these conditions, the semiconductor material 5 was formed. When using a glass substrate with a 500+ polycrystalline silicon thin film, the sheet resistance is 100 to 200Ω/mouth,
Impurity concentration, to''/c1 n)!: l was reduced by 1.?i
After i, the surface of the semiconductor material 5 is washed with an organic detergent to remove the excess phosphorus-based d film remaining on the surface of the material 5.

Note that, in the step of depositing a phosphorus-based thin film during this in-phase doping, not only the laser beam 6 in the ultraviolet region but also ordinary light including the ultraviolet region can be used as well.

(G) Effects of the Invention As is clear from the explanation below, the present invention uses TMP, which has a low bond dissociation energy, as the nQ impurity when doping n-type impurities using a laser beam. Desired 01 with energy laser! :! By doping with impurities, it is possible to achieve high energy efficiency, and with a small number of pulses and low partial pressure, it is possible to secure a negative dose hole and at the same time prevent excess heat from being generated in the semiconductor material plate. Since this eliminates the risk of adverse effects on the formation of semiconductor materials, there is no risk of adverse effects on the formation of semiconductor materials.

[Brief explanation of drawings]

The figure is a conceptual diagram showing the configuration when implementing the method of the present invention. ■...Reaction chamber, 5...Semiconductor material, 6...Laser beam.

Claims (2)

[Claims] (1) When doping a semiconductor material with an n-type impurity using a laser beam, the semiconductor material surface is irradiated with a high-energy laser beam while the semiconductor material surface is in contact with vapor phase trimethylphosphine. , an n-type impurity doping method for doping phosphorus into a location irradiated with the laser beam to make it n-type. (2) When doping a semiconductor material with n-type impurities using a laser beam, light containing low-energy ultraviolet light is applied to the semiconductor material surface while the semiconductor material surface is in contact with vapor phase trimethylphosphine. , or after growing a phosphorous-based thin film on the surface of the semiconductor material by irradiating it with an ultraviolet laser beam, irradiating the surface of the semiconductor material to be doped with n-type impurities with a high-energy laser beam; A method of doping n-type impurities by doping phosphorus into the exposed areas to make them n-type.