JPS61204944A - Insulating film forming method - Google Patents

Abstract

PURPOSE:To provide an insulating film forming method suitable for manufacture of mainly InP field effect transistors and characterized by excellent interface characteristics of III-V compound semiconductors and capability of forming practical gate insulating film, by using phosphorus trichloride (PCl3) and ammonia (NH3) as materials for the insulating film, and specifying a film forming temperature. CONSTITUTION:In forming an insulating film including phosphorus as well as P3N5, phosphorus trichloride (PCl3) and ammonia (NH3) are used as raw materials, and a chemical vapor deposition method is used at a temperature region of 350-250 deg.C. When the film is made at a temperature lower than 250 deg.C, its insulating resistance is low and the film cannot be used as a gate insulating film, Meanwhile, at a temperature higher than 350 deg.C, thermal deterioration of the surface of a semiconductor cannot be avoided, and an accumulating layer cannot be formed on a P-type substrate.

Description

[Detailed description of the invention]

[Technical field] The present invention relates to a ■-v group compound semiconductor (indium phosphide In
This invention relates to a method of forming an insulating film such as a gate insulating film of a field effect transistor using P). [Prior Art] Conventionally, chemical vapor deposition films of alumina, silicon oxide, nitrogen phosphide (P3N, etc.) have been used as gate insulating films for InPt field effect transistors. In chemical deposition, it is desirable for the constituent elements of the gate insulating film to be close to the constituent elements of the semiconductor from the point of view of phase n diffusion at the interface. P3Ns) is
This is advantageous because it contains phosphorus (P), which is a constituent of InP. However, phosphine (PH, ) and ammonia (N
In order to form P3N using the usual method using H3), it is necessary to heat the InP substrate to 500°C or higher, and thermal deterioration of the substrate surface is unavoidable.
We were able to realize a high-performance lS-type field effect chamber with no deterioration and no powder. [11th objective] Ikor, favorite 11 [Objective is IV group compound ゛I':
Conductor customer! A! U'ii characteristics i, bond, the second one can be practically used for gate insulation 11 ri +&, and Et and 11. The purpose of this is to provide a list of suitable insulating films for the production of IFIP field effect Nh transistors. In order to achieve

[! 1 is
ρ, N1, and 11, when forming an insulating film containing phosphorus, use chemical phosphorus (PC93) door 7 fnia (NH3) with raw material car 1 and I=-(and 350℃~250℃) A chemical vapor deposition method is used in the temperature range of ℃.The main advantage is that the material used is different from the conventional technology, and the film is formed in a temperature range that does not cause thermal deterioration of the semiconductor substrate. i-+7 differs in one point. ri is a beautiful reaction tube, 2 is a city air furnace placed around reaction tube 1, and 3 is a beautiful reaction tube.
and 4 is the branched input of reaction tube 1 [15 is anti-1v'
T? 1 and 6 are InP substrates placed inside the reaction tube 1. 7 is &A I! in the axial direction of reaction tube 1. '1 minute/
An example of Ii is yf<. From person 3, ammonia gas diluted with argon gas (
Argon gas containing 51% to 20%) was supplied from the PC 41 arc to the reaction tube inner vessel, respectively. As an example of a reaction tube, when using a stone)) reaction tube with an inner diameter of 8mm, ammonia gas is heated at 3) 5cc/s.
Introduced from human[]3 in 17, while PG kept in greenhouse
fL was bubbled with argon gas, further diluted with 50 cc/win of argon gas, and introduced into the reaction tube 1 from the population 4. 6 InP placed in the reaction tube 1) 1 (
By heating the plate 6 at 300°C for 5 minutes, In
A nitride trench film with a thickness of o and t g could be deposited on the P substrate 6 . Figure 2 shows a film formed by forming a nitride groove film on a plate 1- with a p-type 1nP film at a film formation temperature of 300°C and having a thickness of 0 by the above-mentioned undeveloped I11 method.
．． After forming a film with a thickness of about 1 μm, a gold electrode is formed on the film]7
This is the voltage (v) - 8 pF (pF) characteristic measured between a semiconductor and a metal in a diode. The measurement frequency was 83.3 Hz. When using a nitride groove film formed by undeveloped IJ+, a voltage of 15V is applied to a p-type 1mP substrate, as shown in Figure 2.
By applying a degree of
3 is obtained. That is, it can be seen that it is possible to form a phosphor layer on a p-type 1nP substrate. This word,
It is important to note that the interface state Iff near the valence band of a semiconductor is small. 77-ro/ of the electric field created by the Q electric center of )-3
Scattering is caused by ``f semiconductor inhibition 11
It is considered that the bales are filled in at 3. Therefore, in the case of the nitrided groove film of the present invention, Coulomb scattering is considered to be reduced, so this insulating film can be applied to In the chemical vapor deposition method used, the method of the present invention described above reduces 1
- Even in the above temperature range (250° C. to 350° C.), phosphorus nitride is still formed. However, in the case of a film manufactured at a low temperature of 250° C. or lower, the insulation resistance was low and it could not be used as a gate insulating film. -power, 35
At temperatures as high as 0° C. or higher, thermal deterioration of the semiconductor surface cannot be avoided, making it impossible to form a grainy layer on the p-type substrate. Figure 3 shows that when the film formation temperature 1 is 350°C, P-type InP
The voltage (V)-capacity of the IS diode formed by forming a circulating phosphorus film on the substrate and as described in FIG. 2 is as follows:
1) Shows (pF) characteristics 1°The measurement frequency is 83.8Hz, and unlike the case of t-0 in Figure 2 (film formation temperature 300°C), even when applying a heavy pressure of -7V, the 8% value does not increase at all. You can see that the Noelmi level is pinned. This means that near the valence band of the semiconductor there is a near-field quasi-Q density 1ff.
5a taste that there are many. Therefore, ]]riform IA edition Iff is 350℃ or more,
In the case of , the drain current-drain voltage characteristics of an inverted InP-NIs field effect transistor manufactured using the insulating film formed according to the present invention are as follows: As can be seen from the characteristics shown in the figure, this transistor exhibits characteristics as a field effect transistor. As effective electron mobility, fQQOc+s2/V a se
I got a spy that exceeds c. This value is higher than that when using nitriding leaching (P3Ns) made using a conventional high-temperature process.
This value is about two orders of magnitude larger. This is due to the effect of forming the insulating film at a low temperature and the accompanying reduction in the interface state density described above. As other electrical characteristics of the MIS type field effect transistor, the drift characteristics of the drain current were measured, and as a result, no drift was observed, and a substantially constant drain current could be maintained even after 104 seconds. This is considered to be because the gate insulating film is highly dense, so there are extremely few electron capture levels in the film. [Of course] As explained, according to 11, it is possible to form an insulating film with good interfacial properties between the insulating film and the conductor, and as a result, an electric field with good electrical properties can be formed. An effect transistor can be constructed. 1. Moreover, since the method of the present invention only requires controlling the temperature for forming the insulating film, it has the advantage that semiconductor devices δ having excellent characteristics can be manufactured easily.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the method for forming a phosphorous nitride insulating film according to the present invention, and FIG. 2 is a voltage-6 star characteristic diagram of the insulating film according to the present invention. FIG. 3 is a voltage-series characteristic diagram when the lIg carving and knitting temperature is 50° C., and FIG. 4 is a train voltage-drain current characteristic diagram of a semiconductor device using an insulating film according to the present invention. 1... Reaction tube, 2... Electric furnace, 3.4... Reaction tube population, 5... Reaction tube outlet. 6...InP substrate 1 7...Temperature distribution.

Claims (1)

[Claims] When forming an insulating film by a chemical vapor deposition method, phosphorus trichloride (PCl) is used as a material for the insulating film.
_3) and ammonia (NH_3), and forming the insulating film by chemical vapor deposition at a film forming temperature in the range of 250°C to 350°C.