JPH02226775A - Semiconductor manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor, and more specifically,
Method for manufacturing T (static induction transistor) and 5ITby
The present invention relates to a method of re-diffusion of impurities into a gate portion in a manufacturing method of (electrostatic induction silice).

[Conventional technology]

Generally, in order to make ohmic contact between the gate electrodes of SIT and S[Th, in these manufacturing methods,
This includes a step of re-diffusing impurities (dopants) into the gate area. Conventionally, as this type of method, thermal diffusion method or ion implantation method has been mainly used.

[Problem to be solved by the invention]

However, the above-mentioned conventional thermal diffusion method or ion implantation method requires a thermal process at 1000°C or higher, and during this thermal process, impurities in the gate region diffuse into the channel region, resulting in an increase in channel resistance. For example, when performing an amplification operation, the amount of electrons flowing from the source to the drain (in the case of SIT) or from the cathode to the anode (in the case of SIThy) decreases. This is an inconvenience.

The present invention has focused on the above-mentioned conventional problems, and aims to provide a method for manufacturing a semiconductor in which on-resistance is reduced by lowering the temperature during the step of reimposing impurities into the gate portion.

(Means and Effects for Solving the Problems) In order to achieve the above objectives, the semiconductor manufacturing method according to the present invention will be described with reference to FIG. The configuration is such that the impurity re-diffusion method into part G is a laser doping method. According to this configuration,
Since the impurity re-diffusion into the gate part G can be carried out at low temperature (room temperature), it is possible to prevent the initial diffusion impurities in the gate part G from diffusing and narrowing the channel. Therefore, this re-diffusion itself can also be made uniform and highly accurate.

(Example〕 Embodiments of the present invention will be described below with reference to the drawings.

First, the laser irradiation device and the laser doping method of the manufacturing method according to the present invention will be explained based on FIG. 2, and then the third
Based on the drawings and FIG. 4, the entire manufacturing process including the manufacturing method according to the present invention will be explained using SIT as an example.

As shown in FIG. 2, the laser irradiation device includes a vacuum chamber ti for installing a substrate 1B, and a base material gas 1 in this vacuum chamber 11.
9, a pipe 13 for exhausting gas and air in the vacuum chamber 11, an exhaust device 14 following the vacuum chamber 11, and a quartz window provided in the vacuum chamber 11 for introducing the laser beam 17. 15, and a laser device 16 for oscillating laser light 17. In such a laser irradiation device, the laser doping method includes a first step of adsorbing impurities onto the surface of the substrate 1B, and a laser beam 17 applied to the substrate 18.
and a second step of irradiating impurities to re-diffuse the impurities into the gate portion.

The first step includes the following method.

(1) Method of adsorbing gaseous impurities on the surface of the substrate (method adopted in the first embodiment below) After placing the substrate 18 in the vacuum chamber 11, the inside of this vacuum chamber 11 is evacuated, and then the impurity containing impurities is adsorbed. Create an atmosphere of base material gas 19. In this way, the impurities are adsorbed onto the substrate 18 by irradiation with the zero-order laser beam 17, but this may be done in the atmosphere of the base material gas 19 or by removing the base material gas 19. For example, when forming p-type, a base material gas containing boron B etc. (B2H
6, BF2, etc.) 19, and when forming the other n-type, a base material gas 19 containing phosphorus P or H1tAs, etc.
Use.

(2) Method of forming a film containing impurities (diffusion source film) on the substrate surface (method adopted in the second embodiment below) Forming a diffusion B film on the substrate surface by vacuum evaporation, plasma CVD, etc. For example, in the plasma CVD method, an a-BH film or BNII is formed as a p-swell diffusion source, and an n
The swelling diffusion source film is formed of an a-PH film or PNlll[. Also spread 11111 using the spin code method! It is also good to apply 0 For example, p swelling diffusion fsll! The formation of HOlA
A film-forming coating liquid containing B is used. On the other hand, for the formation of n-swelling diffusion ays, an S, i02-based coating solution containing phosphorus P is used. All of these are liquid substances in which additives (diffusion impurities, glass forming agents, etc.) are dissolved in a solvent (alcohol-based), and can be easily applied onto a substrate using the spin code method. The impurity is diffused into the substrate by irradiating the substrate with the diffusion source film formed in this way with a laser through the diffusion source film. Note that by variously changing the concentration of the solution and/or the rotation speed of the spin code, the film thickness can be controlled, and the amount of diffusion (or concentration) into the substrate can be indirectly controlled. After the re-diffusion is completed, the diffusion source film is removed (not shown above; see second embodiment below for details).

Next, the second step of irradiating the substrate 1B with the laser beam 17 will be described. 9, - the light 17 oscillated from the laser device 16
is a substrate installed in the vacuum chamber 11 through the quartz window 15.
18 is irradiated. The position of irradiation can be moved and set freely by moving the laser beam 17 or the substrate 18.

The laser device 16 uses a laser having an appropriate wavelength that matches the desired re-diffusion depth and concentration from among excimer lasers such as XeC1 and rF, Ar lasers, YAG lasers, etc., and adjusts the irradiation time and pulse. The impurities are re-diffused into the substrate 18 by controlling the number of times.

3 and 4 are diagrams showing an example of a manufacturing method including a semiconductor manufacturing method according to the present invention, taking the manufacturing of an SIT as an example.

FIGS. 3(a) to 3(g) are manufacturing process diagrams of the SIT according to the first embodiment of the present invention, in which the first conductivity type is the n-type, and the second conductivity type is the n-type.
This is an example of manufacturing an n-channel SIT using p-type conductivity. This example uses the laser doping method described above.
The first step uses a method in which gaseous impurities are adsorbed onto the substrate surface (FIG. 3(f) process diagram).

Figure 3(a): n-type silicon substrate doped with n-type impurities such as phosphorus P by epitaxial growth on an n-type silicon substrate.
Grow the epitaxial layer.

Alternatively, an n-type impurity is diffused into an n-silicon substrate to form a highly concentrated n" region. In this way, using phosphorus P as the n-type impurity, the phosphorus concentration is 1xto'.~5x10"7c.
~3 n′ region 1 and phosphorus concentration 1×l Q l! ~to
``A silicon substrate having n- regions 2 of 7c to 3 is formed.

FIG. 3(b) P-type impurities such as boron and IB are diffused on the surface of +n- region 2 through a mask, and boron concentration lXl0
20 striped regions 3 of "~5XlO" 7c~3 are formed. This p0 area 3 becomes the embedding area.

Fig. 3 <c>: A 95% epitaxial layer 4 is formed using SiH4 containing phosphorus P as a raw material for embedding the p'' region 3.
Laminated to a thickness of 5 to 10 μm at 0°C (phosphorus concentration IXI O
"~10"7c~3).

FIG. 3(d) Further impurity diffusion is performed on the surface of the +n- epitaxial layer 4, and the n9 region 5 (phosphorus concentration lX 10
"~1 G"7c~3) is formed.

Figure 3(e): In order to re-diffuse impurities into the gate part, the n-epitaxial layer 4 and the n'' layer formed on this surface
After removing unnecessary portions of the region 5 by etching, a mask region 6 of AI or 5i02 or the like is formed as a mask material.

FIG. 3(f): The substrate 1B provided with the mask region 6 is placed in a vacuum chamber 11 of a laser irradiation device. and vacuum chamber
Make a vacuum inside the l and add 5% B2H6 of the l&H2 dilution.
Next, XaCj excimer laser light (wavelength: 308 mm) 17 is irradiated perpendicularly to the p9 region 3 of the substrate 18 through the quartz 2115. When the irradiation energy is IJ/cm2・5hot and one irradiation, the boron concentration is 3×10"7c~3. Cleanliness O', p of l#rn
"Li region 7 has been formed. At this time, if you want to increase the impurity concentration, you can increase the number of irradiated countries. If you want to increase the diffusion depth, you can increase the energy of the laser beam 17. , the base material gas 82H6 may be removed before laser irradiation.

FIG. 3(g): To take out the electrode, mask area 6 is removed, and finally electrode 8.9 made of a metal thin film such as AI,
By forming IO, 31T is completed.

FIGS. 4(a) to 4(h) are manufacturing process diagrams of the SIT according to the second embodiment of the present invention, and similar to the IR1 embodiment, the n-channel SIT
This is an example of IT manufacturing. In this example, the first step of the laser doping method described above is [Ion containing impurities on the substrate surface].
I (method of forming a diffused fig) was used (Fig. 4 (
f) and (g) process diagram).

Figure 4 (a) N-type silicon substrate doped with n-type impurities such as phosphorus P by epitaxial growth on a 2n”-type silicon substrate.
``Grow epitaxial layer. Alternatively, n-type impurities are diffused into an n-silicon substrate to form a highly concentrated 00 region. In this way, assuming that the n-type impurity is phosphorus P, the phosphorus concentration is 1 x lO''~5 x 10''/c~3n''
A silicon substrate is formed having a region table and an n- region 2 having a phosphorus concentration LX of 10'' to 1014/cm3.

FIG. 4(b): A p-type impurity such as boron B is diffused into the surface of the n-region 2 through a mask, and the boron concentration txto'
A striped p9 region 3 of 7c to 5×10” is formed. This p1 area 3 becomes the embedding area.

Figure 4(c): An n epitaxial layer 4 for burying the p"fl region 3 is formed using SiH4 containing phosphorus P as a raw material.
Laminated to a thickness of 5 to 10 μm at 0°C (phosphorus concentration I
0''~10'''/e~3).

FIG. 4(d): Further impurity diffusion is performed on the surface of the n- epitaxial layer 4, and the n9 region 5 (phosphorus concentration lXl0''~
10"7c~3).

Figure 4(e): To re-diffuse impurities into the gate area,
After removing unnecessary portions of the n-epitaxial layer 4 and the n0 region 5 formed on its surface by etching, a mask region 6 of AI or S102 or the like is formed as a mask material.

Figure 4 <r>: A coating solution for forming a 5102-based film containing boron mB is applied as a p-type diffusion source film to the surface of the p'' region 3 by a spin code method.Or by a CVD method t's lH4
B2O3+S using +82H6+02 gas etc. as raw material
For example, plasma C to form 102 diffusion source films 7A.
In the VD method, BNM may be formed using B2H6 + N2 gas as a raw material, or a-BH may be formed using B2H6 gas as a raw material.
In this example, the B2O3+510 film may be formed.
The substrate 18 on which the expansion source film 7A of No. 2 was formed was placed in a vacuum chamber 11 of a laser irradiation device. After evacuating the vacuum chamber 11, the XeCl excimer laser beam (wavelength 308
mm) 17 was irradiated.

The irradiation energy was IJ/cm2・5hot, and when irradiated once, the boron concentration was 3X10”・/c
A p0 region 7 with m3 and El of 0.1 was formed.

FIG. 4(g) = After laser irradiation, the diffusion source film 7A of 8203+5i02 and the mask region 6 are removed by etching using fluoric acid or the like.

FIG. 4(h): To take out the electrodes, SIT is completed by finally forming electrodes 8.9.10 made of a thin metal film such as Al.

By forming the p♦ region 7 using laser doping as in the first and second embodiments, the same process can be performed at room temperature. Therefore, the p9 region 3, which is the buried layer, is not heated after being formed, and as a result, it is possible to prevent the occurrence of inadvertent diffusion as seen in the prior art. That is, the desired SIT can be obtained as designed.

Regarding the manufacturing method for 5ITb, there is no difference from SIT in terms of the manufacturing process of st'rhy and the configuration of s+'rhy, so the same manufacturing method as that of SIT can be applied.

(Effects of the Invention) As explained above, the semiconductor manufacturing method of the present invention
In the process of forming the ohmic layer on the electrode side of lT or sI'rhy, since laser doping is used for impurity diffusion, the high concentration region, which is the augmented region, is not heated after formation.

As a result, it becomes possible to prevent the accidental diffusion that occurs during the thermal process in the conventional technology.

That is, the initially formed distribution of impurities can be maintained. Therefore, the channel resistance between the source and drain or between the cathode and anode can be lowered compared to the conventional one. That is, since the on-resistance can be reduced, electrons flowing from the source to the drain or from the cathode to the anode can be held w1 as designed values when performing an amplification operation.

[Brief explanation of the drawing]

Fig. 1: Explanatory diagram of the semiconductor manufacturing method according to the present invention Fig. 2: Conceptual diagram of the laser irradiation device Fig. 3: Diagram of the SIT manufacturing process of the first embodiment of the present invention Fig. 4 Figure: Manufacturing of SIT according to the second embodiment of the present invention.
・ 2 ・ ・ 3 ・ ・ 4 ・ ・ 5 ・ ・ 6 ・ ・ 7 ・ ・ 7 A ・ 8 ・ 9 ・ ・ Construction process diagram・n0 area 10・・・n− area 11・・・p0 area 12.13・・N-epitaxial layer・n0 region 14・・・Mask region 15・・・P0 region 16・・・Diffusion source fl 17・・・Drain electrode 18・・・Gate electrode 19・・・G・・・Source electrode・vacuum Tank, piping, exhaust equipment, quartz window, laser equipment, laser light, substrate, base material gas, gate section

Claims (2)

[Claims] (1) A semiconductor manufacturing method characterized in that the impurity re-diffusion method into the gate portion is a laser doping method in the SIT manufacturing method. (2) The method for manufacturing a semiconductor according to claim 1, wherein SIT is SIThy.