JPH04307931A - Forming method of p-type introducing region - Google Patents

Abstract

PURPOSE:To form a P-type impurity introducing region easily with excellent controllability in the specified concentration of P-type impurities by using boron as the P-type impurity, employing quick heat treatment by light irradiation as heat treatment and conducting the heat treatment in an atmosphere containing hydrogen or steam. CONSTITUTION:An insulating film 2 containing a P-type impurity is formed onto a semiconductor substrate 1 composed of Si, and the P-type impurity contained in the insulating film 2 is introduced into the semiconductor substrate 1 from the insulating film 2 through heat treatment to the semiconductor substrate 1 and the insulating film 2. In the forming method of such a P-type impurity introducing region 4, boron is used as the P-type impurities, quick heat treatment in a short time by light irradiation is employed as said heat treatment, and the heat treatment is conducted in an atmosphere comprising hydrogen or steam. The insulating film 2 containing boron and composed of SiO2 is formed onto the Si substrate 1, and quick heat treatment using an infrared lamp is performed in a mixed gas atmosphere at the ratio of hydrogen to nitrogen of 1:1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a p-type impurity doped region in a semiconductor substrate made of Si from the top surface thereof.

0002

2. Description of the Related Art Conventionally, an n-type semiconductor substrate made of Si is used, and a p-channel type has a structure in which a p-type impurity doped region is formed as a channel region from the upper surface side of the semiconductor substrate. MOS field effect transistors are widely available.

Conventionally, in forming a p-type impurity doped region as a channel region in such a p-channel MOS field effect transistor, (i) boron (B) is deposited on a semiconductor substrate made of Si and having n-type conductivity. (ii) Next, the semiconductor substrate and the insulating film are subjected to rapid heat treatment in a short period of time by light irradiation in a nitrogen atmosphere. A method for forming a p-type impurity introduced region has been proposed, which includes a step of introducing boron as a p-type impurity contained in the insulating film into the semiconductor substrate.

According to such a conventional method for forming a p-type impurity doped region, a p-type impurity doped region is formed in a semiconductor substrate.
Since the p-type impurity is introduced into the insulating film containing the p-type impurity formed thereon by heat treatment, the p-type impurity introduced region is formed into the p-type impurity in the semiconductor substrate.
It has the feature that it can be formed without causing crystal defects, which is the case with other conventional methods for forming p-type impurity-introduced regions, which are formed by implanting p-type impurity ions.

[0005]

[Problems to be Solved by the Invention] In the conventional method for forming a p-type impurity-introduced region described above, in the step of forming the p-type impurity-introduced region by heat treatment, the semiconductor substrate is formed between the semiconductor substrate and the insulating film. It is made of Si oxide and has an oxide layer as thin as 10A. If the surface of the semiconductor substrate is exposed to the outside air before the process of forming an insulating film on the semiconductor substrate, or if the semiconductor substrate is placed in a reaction chamber to form an insulating film on it, it may remain in the reaction chamber. If the surface of the semiconductor substrate comes into contact with the oxygen present in the semiconductor substrate, or even if an insulating film is
This is because if the semiconductor substrate is formed of an oxide such as 2, the surface of the semiconductor substrate will come into contact with the oxygen used at that time.

Therefore, in the conventional method for forming a p-type impurity doped region described above, boron as a p-type impurity is
It is introduced into the semiconductor substrate through the oxide layer between the semiconductor substrate and the insulating film described above. At this time, the concentration of boron as a p-type impurity in the oxide layer increases over time from the start of the heat treatment, and then does not change as the heat treatment time progresses, so that Accordingly, the diffusion coefficient of boron as a p-type impurity in the oxide layer increases as the heat treatment time elapses from the start of the heat treatment, and then does not change as the heat treatment time progresses.

Therefore, in the conventional method for forming a p-type impurity doped region described above, in the step of forming the p-type impurity doped region by heat treatment, the p-type impurity doped region is
The concentration of boron as a type impurity depends on the heat treatment time.
From FIG. 8, which shows the relationship between the concentration of boron as a p-type impurity on the surface of the p-type impurity-introduced region, which was actually measured, the relationship between the sheet resistance of the p-type impurity-introduced region and the heat treatment time was also measured. As is clear from FIG. 9, it increases at a relatively large rate of change over time from the start of the heat treatment, and then stops changing as the heat treatment time progresses.

By the way, in the conventional method for forming a p-type impurity introduced region described above, in the step of forming the p-type impurity introduced region by heat treatment, the heat treatment is performed in a nitrogen atmosphere. , the time until the concentration of boron as a p-type impurity in the p-type impurity-introduced region stops changing (this is designated as ta) is:
As is clear from Fig. 8, the temperature during heat treatment was set to 1000
℃, it is relatively long, such as 50 seconds. Therefore, if heat treatment is performed until after the time ta when the concentration of boron as a p-type impurity in the p-type impurity introduction region stops changing, after that time ta, p
Since the p-type impurity concentration in the p-type impurity-introduced region hardly changes, the p-type impurity-introduced region can be formed to a predetermined p-type impurity concentration, but in this case, the p-type impurity-introduced region is relatively deeply formed. Moreover, if the heat treatment is performed up to the point before the above-mentioned point ta,
As is clear from the above, even if the p-type impurity doped region can be formed shallowly, it is possible to form the p-type impurity doped region with good controllability by setting the p-type impurity concentration to a predetermined value. cannot be easily formed.

From the above, in the conventional p-type impurity doped region formation method described above, it is desirable to form the p-type impurity doped region shallowly with a predetermined p-type impurity concentration. However, it has the disadvantage that it is difficult to form in this way. Therefore, the present invention aims to propose a novel method for forming a p-type impurity-introduced region without the above-mentioned drawbacks.

0010

[Means for Solving the Problems] The method for forming a p-type impurity doped region according to the present invention is similar to the conventional method for forming a p-type impurity doped region described above. (ii) introducing p-type impurities contained in the insulating film from the insulating film into the semiconductor substrate by forming an insulating film containing a type impurity; and (ii) heat treating the semiconductor substrate and the insulating film. It has a process.

However, in the method for forming a p-type impurity introduced region according to the present invention, (iii) boron is used as the p-type impurity, and (iv) the above heat treatment is performed. , rapid heat treatment in a short period of time by light irradiation, and the heat treatment is performed in an atmosphere containing hydrogen or water vapor.

0012

[Operations/Effects] According to the method for forming a p-type impurity doped region according to the present invention, a p-type impurity doped region can be formed in a semiconductor substrate and on top of the same in the same manner as in the conventional p-type impurity doped region forming method described above. Since the p-type impurity is introduced into the insulating film containing the p-type impurity formed by heat treatment, the p-type impurity-introduced region is formed in a manner different from that in the conventional p-type impurity-introduced region formation method described above. Similarly, it has the characteristic that it can be formed without crystal defects.

However, in the method of forming a p-type impurity doped region according to the present invention, in the step of forming the p-type impurity doped region by heat treatment, the heat treatment is different from that in the conventional p-type impurity doped region forming method described above. The difference is that it is carried out in an atmosphere containing hydrogen or water vapor. For this reason, in the step of forming a p-type impurity doped region by heat treatment, the semiconductor substrate is formed between the semiconductor substrate and the insulating film for the reason described above in the case of the conventional p-type impurity doped region formation method. 10A
By having such a thin oxide layer, the concentration of boron as a p-type impurity in the p-type impurity doped region changes at a relatively large rate over time from the start of heat treatment. The concentration of boron as a p-type impurity in the p-type impurity introduction region stops changing from the start of the heat treatment until the concentration of boron as a p-type impurity in the p-type impurity introduction region stops changing. This is much shorter than in the case of the p-type impurity doped region formation method.

Therefore, in the method of forming a p-type impurity doped region according to the present invention, the p-type impurity doped region has a predetermined p-type impurity concentration, and the p-type impurity doped region is formed using the conventional p-type impurity doped region forming method described above. Much shallower than can be formed,
It has good controllability and can be easily formed.

[0015]

[Embodiment 1] Next, an embodiment of the method for forming a p-type impurity introduced region according to the present invention will be described with reference to FIG.

An insulating film 2 made of SiO2 containing boron (B) as a p-type impurity at a concentration of 18 atomic % is formed on a previously prepared semiconductor substrate 1 made of Si and of n-type (FIG. 1A). , by the CVD method, which is known per se.
It is deposited to a thickness of 5000 Å (FIG. 1B). In this case, between the semiconductor substrate 1 and the insulating film 2,

In the section [Problem to be Solved by the Invention], the conventional p
For the reason described in the case of the type impurity introduction region forming method, the oxide layer 3 made of Si oxide constituting the semiconductor substrate 1 and having a thin thickness of 10 Å is formed.

Next, with respect to the semiconductor substrate 1 and the insulating film 2,
The temperature was increased to 1000℃ by light irradiation using an infrared lamp.
Rapid heat treatment in a short time is performed using hydrogen and nitrogen.
By performing this in an atmosphere containing hydrogen made of a mixed gas of 1, boron (B) as a p-type impurity contained in the insulating film 2 is introduced into the semiconductor substrate 1,
Therefore, a p-type impurity doped region 4 is formed in the semiconductor substrate 1 (FIG. 1C).

Next, regarding the insulating film 2 and the oxide layer 3,
The insulating film 2 and oxide layer 3 are etched using a mixture of fluorine and water as an etchant.
It is removed by dissolution from the top of the semiconductor substrate 1 (FIG. 1D). More than,
This is an example of a method for forming a p-type impurity introduced region according to the present invention.

According to the method for forming a p-type impurity introduced region according to the present invention, the p-type impurity introduction region 4 is formed in the semiconductor substrate 1 in the same manner as in the conventional method for forming a p-type impurity introduction region described above. Since the p-type impurity introduced region 4 is formed by introducing boron as a p-type impurity through heat treatment from the insulating film 2 containing boron as a p-type impurity formed thereon, the p-type impurity introduced region 4 is Similar to the method for forming a p-type impurity-introduced region, this method has the characteristic that it can be formed without crystal defects.

However, the p
In the case of the method for forming a p-type impurity introduced region, the p-type impurity introduced region 4
In the step of forming by heat treatment (FIG. 1C), the heat treatment is performed in an atmosphere containing hydrogen, unlike in the case of the conventional p-type impurity introduction region formation method described above. Therefore, in the step of forming the p-type impurity introduced region 4 by heat treatment (FIG. 1C), by having the oxide layer 3 between the semiconductor substrate 1 and the insulating film 3,
As in the case of the conventional p-type impurity doped region forming method described above, the concentration of boron as a p-type impurity in the p-type impurity doped region 4 changes at a relatively large rate over time from the start of the heat treatment. The concentration of boron as a p-type impurity in the p-type impurity introduction region 4 stops changing from the start of the heat treatment until the concentration of boron as a p-type impurity in the p-type impurity introduction region 4 stops changing. This is much shorter than in the case of the p-type impurity introduced region formation method.

This can be confirmed by measuring the relationship between the concentration of boron as a p-type impurity on the surface of the p-type impurity-introduced region 4 and the heat treatment time in the step of forming the p-type impurity-introduced region 4 by heat treatment (FIG. 1C). However, Figure 2
The results shown are obtained, and when the relationship between the sheet resistance of the p-type impurity introduced region 4 and the heat treatment time was measured,
The results shown in FIG. 3 were obtained, the measurement results shown in FIGS. 2 and 3, and the corresponding results shown in FIGS. 8 and 9 in the case of the conventional p-type impurity doped region formation method described above. This will become clear by comparing the measurement results shown.

From the above, in the case of the p-type impurity doped region forming method according to the present invention shown in FIG. It is much shallower than that which can be formed by the type impurity-introduced region formation method, and can be easily formed with good controllability.

[0023]

[Embodiment 2] Next, referring to FIGS. 4 to 7, p-channel type M
An example will be described in which an OS field effect transistor is manufactured. 4 to 7, parts corresponding to those in FIG. 1 are designated by the same reference numerals.

[0024] Made of Si and containing 3×101 n-type impurities
SiO is deposited on the upper surface side of the semiconductor substrate 1 prepared in advance, which has n-type by introducing it at a concentration of 7 cm-3.
A field insulating film 12 of 2.0 mm was formed to a thickness of 5000 Å by a thermal oxidation process known per se so as to define the element formation region 11 (FIG. 4A).

Next, SiO2 is formed on the semiconductor substrate 1, continuously extending over the field insulating film 12 and the element forming region 11, and containing boron (B) as a p-type impurity in an amount of 4 atomic %. The insulating film 2 made of
It was formed to a thickness of 1000 Å by the method (FIG. 4B). In this case, the element formation region 11 of the semiconductor substrate 1 and the insulating film 2
An oxide layer 3 made of Si oxide and constituting the element formation region 11 was formed between the two.

Next, the semiconductor substrate 1 and the insulating film 2 are subjected to rapid heat treatment for a short time of 20 seconds at a temperature of 920° C. by irradiation with light from an infrared lamp using a 1:1 mixture of hydrogen and nitrogen. By performing this in an atmosphere containing gaseous hydrogen, boron (B) as a p-type impurity containing boron is introduced from the insulating film 2 into the semiconductor substrate 1. A p-type impurity doped region 4 was formed in (FIG. 5C).

Next, the insulating film 2 and oxide layer 3 are etched using a mixture of fluorine and hydrogen as an etchant.
It was removed by dissolution from the top of the semiconductor substrate 1 (FIG. 5D).

Next, on the p-type impurity doped region 4, SiO
A gate insulating film 13 of 2.2 was formed to a thickness of 50 Å by a thermal oxidation treatment in a dry oxygen atmosphere, which is known per se (FIG. 6E).

Next, a gate electrode layer 14 made of polycrystalline silicon and provided with conductivity is formed on the gate insulating film 13 so as to bisect the element formation region 11 when viewed from above.
was formed by a lithographic method known per se (FIG. 6F).

Next, using the gate electrode 14 as a mask, a known BF2 ion implantation process is performed, and then,
By performing rapid thermal annealing treatment, a source region 15 and a drain region 1 having p+ type are formed in the element forming region 11 at both positions sandwiching the gate electrode 14.
6, thereby forming a p-type channel region 17 extending from the p-type impurity doped region 4 between the source region 15 and the drain region 16 (FIG. 7G).
).

Next, an interlayer insulating film 18 made of SiO2 is formed on the semiconductor substrate 1 and extends to cover the field insulating film 12, the gate insulating film, and the gate electrode 14.
Next, a window 14 for exposing the gate electrode 14 to the outside is formed in the interlayer insulating film 18, and a source region 15 and a drain region 1 are formed through the interlayer insulating film 18 and the gate insulating film 13.
forming windows 20 and 21 that respectively expose the windows 6 to the outside;
Next, on the interlayer insulating film 18, a gate electrode 22, a source electrode 23 and a A drain electrode 24 was formed (FIG. 7H).

The above is an example in which a p-channel type MOS field effect transistor is manufactured by applying the p-type impurity-introduced region forming method according to the present invention.

According to the p-channel MOS field effect transistor manufactured in this manner, the channel forming region 17 is formed from the p-type impurity doped region 4 formed by the p-type impurity doped region forming method according to the present invention. Therefore, it has a high surface concentration of 1019 cm-3 and a sufficiently shallow depth of 200 A, and therefore has excellent characteristics such as leakage current resistance.

The above description merely shows one embodiment of the method for forming a p-type impurity introduced region according to the present invention, and in the embodiment of the method for forming a p-type impurity introduced region according to the present invention shown in FIG. The p-type impurity introduction according to the present invention shown in FIG. The same effects as in the area forming method were obtained.

Furthermore, in the above description, the case where an infrared lamp is used for light irradiation for heat treatment to form a p-type impurity introduced region is shown. Other lamps producing heatable radiation may be used, and other modifications may be made without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing sequential steps of an embodiment of a method for forming a p-type impurity-introduced region according to the present invention.

FIG. 2 is a diagram showing the relationship between the surface concentration of the p-type impurity-doped region and the heat treatment time in the step of forming the p-type impurity-doped region by heat treatment, to explain the method for forming the p-type impurity-doped region according to the present invention. .

FIG. 3 is a diagram showing the relationship between the sheet resistance of the p-type impurity-introduced region and the heat treatment time in the step of forming the p-type impurity-introduction region by heat treatment, to explain the method for forming the p-type impurity-introduction region according to the present invention; It is.

FIGS. 4A and 4B are schematic cross-sectional views showing successive steps of an embodiment in which a p-channel MOS field effect transistor is manufactured by applying the p-type impurity-introduced region forming method according to the present invention; FIGS.

5 is a schematic diagram showing an example of manufacturing a p-channel MOS field effect transistor by applying the method for forming a p-type impurity-introduced region according to the present invention, in sequential steps following the sequential steps in FIG. 4; FIG.

6 is a schematic diagram of sequential steps following the sequential steps of FIG. 5, showing an example of manufacturing a p-channel MOS field effect transistor by applying the p-type impurity-introduced region forming method according to the present invention; FIG. FIG.

7 is a schematic diagram of sequential steps following the sequential steps of FIG. 6, showing an example of manufacturing a p-channel MOS field effect transistor by applying the p-type impurity-introduced region forming method according to the present invention; FIG. FIG.

FIG. 8 is a diagram illustrating the relationship between the surface concentration of the p-type impurity-doped region and the heat treatment time in the step of forming the p-type impurity-doped region by heat treatment, to explain the conventional method for forming the p-type impurity-doped region.

FIG. 9 is a graph of the p-type impurity-introduced region versus heat treatment time in the step of forming the p-type impurity-introduced region by heat treatment, which is used to explain a conventional p-type impurity-introduced region forming method;
FIG.

[Explanation of symbols]

1 Semiconductor substrate 2
Insulating film 3
Oxide layer 4 P-type impurity introduction region 11 Element formation region 12 Field insulating film 13 Gate insulating film 1
4 Gate electrode 15
source area 16
drain region 17
Channel forming area 18
Interlayer insulating film 19, 20, 21 window

Claims (1)

[Claims] 1. A step of forming an insulating film containing a p-type impurity on a semiconductor substrate made of Si, and heat treatment of the semiconductor substrate and the insulating film, so that the semiconductor substrate has the following properties: In the method for forming a p-type impurity introduced region, the p-type impurity introduction region forming method includes a step of introducing a p-type impurity contained in the p-type impurity, wherein boron is used as the p-type impurity, and the heat treatment is a rapid heat treatment in a short time by light irradiation,
A method for forming a p-type impurity-introduced region, characterized in that the heat treatment is performed in an atmosphere containing hydrogen or water vapor.