JPH04162618A - Manufacture of semiconductor device; ion implantation apparatus; semiconductor device - Google Patents

Abstract

PURPOSE:To surely reduce a defect which is produced at an ion implantation operation and which is left by a method wherein, immediately after ions have been implanted in a low-temperature state, a semiconductor substrate is heated to a high temperature. CONSTITUTION:During the period from the start of an ion implantation treatment to the activation treatment of a substance introduced into a semiconductor substrate 1, the temperature of the semiconductor substrate 1 is kept at -100 deg.C or lower. Immediately after the finish of the ion implantation treatment, the semiconductor substrate 1 is heated by using a halogen lamp, microwaves or an energy beam in such a way that the time required for the temperature rise up to a temperature of 600 deg.C or higher is within one minute. This apparatus is provided with the following: a specimen stand used to hold the semiconductor substrate 1 so as to be freely detachable; an ion-beam formation means used to radiate the ion beam of a desired substance; a cooling means used to cool the substrate 1 down to -100 deg.C or lower; and a heating means used to heat it instantaneously up to 600 deg.C or higher. Thereby, it is possible to avoid that a defect 2 produced at the ion implantation treatment is stabilized when it is left at a temperature near room temperature, the defect 2 can be restored easily by a heating treatment, and the residual defect 2 can be reduced surely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device and an ion implantation apparatus, and particularly to a technique that is effective when applied to an ion implantation step in a wafer process.

[Conventional technology]

For example, in the field of manufacturing semiconductor devices such as IC memories and logic LSIs, ion implantation technology has become indispensable as a means of introducing impurity elements into semiconductor substrates.

The elementary process of ion implantation consists of collision, excitation, and ionization between ions and solid atoms constituting the semiconductor substrate, and is a destructive phenomenon that results in the creation of many point defects or complexes thereof within the solid. Therefore, the biggest challenge in applying ion implantation technology to semiconductor device manufacturing technology is how to recover the crystal defects that occur with ion implantation. and has been resolved. However, in recent years, with the significant progress in miniaturization of semiconductor devices, problems caused by crystal defects in new areas that did not pose a problem before have become apparent.

One way to control such crystal defects caused by ion implantation is to lower the temperature of the semiconductor substrate during ion implantation. The effect of lowering the implantation temperature on residual defects will be explained with reference to FIGS. 7(a) to 7(C). Figure (a) shows the semiconductor substrate I during ion implantation.
Figure (b) is a diagram schematically showing a cross section of the substrate surface when ion implantation is performed at room temperature, and Figure (c) is a diagram showing the depth of the introduced impurity. FIG. 3 is a diagram showing distribution in the horizontal direction. When the substrate temperature is lowered, the defects 4 (end-of-range defects) formed at the base of the concentration distribution curve and the defects 3 near the range are significantly reduced compared to when the substrate temperature is at room temperature. However, for defects 2 formed in a region shallower than the range, lowering the temperature has little effect. Regarding the effect of lowering the substrate temperature during ion implantation on reducing residual defects, see, for example, "Applied Physics Letters".
hysics Letters), 41'', No. 53
7 to 539 (1982).

[Invention or problem to be solved]

The reason for the reduction in residual defects by ion implantation at low temperatures is that by keeping the substrate temperature low, cell annealing during ion implantation is suppressed and stable defects are generated that are difficult to recover from. It is believed that this is to prevent it.

However, in conventional low-temperature implantation, after ion implantation is performed with the substrate temperature at a low temperature, the substrate temperature is returned to room temperature, taken out of the device, and then loaded into a designated annealing device, etc., and then implanted. Because the method uses heat treatment to activate impurities, some annealing occurs during the process of returning the substrate temperature from low temperature to room temperature. In other words, the reason why the conventional low-temperature implantation was not yet sufficiently effective in preventing the generation of residual defects is thought to be due to the process of returning (leaving) the material to room temperature.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device that can reliably reduce defects that occur and remain during ion implantation.

Another object of the present invention is to provide an ion implantation apparatus that can easily recover crystal defects generated during ion implantation and reliably reduce residual defects.

Still another object of the present invention is to provide a semiconductor device that can reduce product defects and improve operational reliability.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device in which a desired substance is introduced by ion implantation into a semiconductor substrate on which a semiconductor device is formed,
A first step of performing ion implantation while keeping the temperature of the semiconductor substrate at -100°C or less, and a second step of instantly heating the semiconductor substrate to a temperature of 600°C or more immediately after the first step. This includes:

Further, in the method for manufacturing a semiconductor device according to the present invention, the semiconductor substrate is heated using a halogen lamp, a microwave, or an energy beam.

Further, in the method for manufacturing a semiconductor device according to the present invention, the time required to raise the temperature to 600° C. or higher is within 1 minute immediately after the completion of ion implantation into the semiconductor substrate.

Further, the method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device in which a desired substance is introduced by ion implantation into a semiconductor substrate on which the semiconductor device is formed, and the method includes introducing a desired substance by ion implantation from the start of the ion implantation process. The temperature of the semiconductor substrate is maintained at -100° C. or lower until the substance introduced into the semiconductor substrate is activated.

Further, the ion implantation apparatus of the present invention includes a sample stage that removably holds a semiconductor substrate, an ion beam forming means for irradiating the semiconductor substrate held on the sample stage with an ion beam of a desired substance, and a sample stage. a cooling means disposed in a part of the specimen stage to cool the semiconductor substrate held on the sample stage to below -100°C; and a cooling means provided near the specimen stage to cool the semiconductor substrate held on the specimen stage; It is equipped with a heating means for instantaneously heating to a temperature of 600° C. or higher at any time.

Further, in the ion implantation apparatus according to the present invention, the heating means is
It consists of a halogen lamp, a microwave, or an energy beam.

Further, a semiconductor device according to the present invention is manufactured by the method for manufacturing a semiconductor device according to claim 1, 2.3, or 4.

Further, a semiconductor device according to the present invention is manufactured using the ion implantation apparatus according to claim 5 or 6.

[Effect]

According to the method for manufacturing a semiconductor device of the present invention described above, by heating to a high temperature immediately after ion implantation in a low temperature state,
Defects generated during ion implantation are prevented from being stabilized by being left near room temperature, the defects can be easily recovered by heat treatment, and residual defects can be reliably reduced.

Further, according to the method for manufacturing a semiconductor device of the present invention, the semiconductor substrate is maintained at a low temperature from the start of ion implantation at low temperature to the activation treatment of the introduced substance by heating, so that the ion implantation is not performed. The semiconductor substrate is not left at room temperature. This prevents the defects generated during ion implantation from becoming stabilized by being left near room temperature, and allows the defects to be easily recovered by heat treatment, thereby reliably reducing the number of remaining defects.

Further, according to the ion implantation apparatus of the present invention, ions are implanted while the semiconductor substrate is kept at a low temperature by the cooling means disposed on the sample stand, and immediately after the completion of the ion implantation, the semiconductor substrate is placed on the sample stand. It is possible to perform an operation of immediately heating the sample to a high temperature using a heating means while the sample is being held at a high temperature. This prevents the defects generated during ion implantation from becoming stabilized by being left near room temperature, and allows the defects to be easily recovered by heat treatment, thereby reliably reducing the number of remaining defects.

Further, according to the semiconductor device according to the present invention, claims 1 and 2
．． Since it is manufactured by the semiconductor device manufacturing method described in 3 or 4, it is possible to reduce product defects and improve operational reliability.

Further, according to the semiconductor device of the present invention, since it is manufactured using the ion implantation apparatus according to claim 5 or 6,
It is possible to reduce product defects and improve operational reliability.

[Example 1] Hereinafter, an example of a method for manufacturing a semiconductor device according to an embodiment of the present invention and an example of an ion implantation apparatus used therein will be described in detail with reference to the drawings.

1(a) to (C) and FIG. 2(al, Q)] are schematic diagrams showing an example of the effects of the actual semiconductor device manufacturing method and ion implantation equipment in this book, in comparison with the case of the prior art. FIG. 3 is a schematic cross-sectional view schematically showing an example of the configuration of the ion implantation apparatus of this embodiment.

First, an example of the configuration of the ion implantation apparatus of this embodiment will be explained with reference to FIG.

A disk-shaped sample stage 100, on which a plurality of semiconductor substrates 1 are removably held, is supported by a rotating shaft 101 from the back side and rotated. Sample stand 100
The holding surface of the semiconductor substrate 1 is irradiated with an ion beam 102 of a desired substance emitted from an ion source (not shown), and the beam deflector +03 directs the ion beam 102 in a direction perpendicular to the rotation direction of the semiconductor substrate 1. A scan is performed. That is, the entire surface of the semiconductor substrate 1 is irradiated with the ion beam 102 by rotating the sample stage 1000 times and scanning the ion beam 102.

A refrigerant flow path 00a is formed inside the sample stage 100 and the rotating shaft 101, through which a refrigerant 104 such as a liquefied gas having a temperature of -100° C. or lower flows from the outside. The structure is such that the semiconductor substrate 1 being held is cooled from the back side to a low temperature of -100''C or less.

In this case, in the vicinity of the sample stand 100, the sample stand 100 is
A halogen lamp 105 is placed on the semiconductor substrate 1 held on the sample stage 100 and is turned on at any time to quickly heat the semiconductor substrate 1 held on the sample stage 100 to, for example, 60'C. The structure is such that it can be heated to a temperature higher than that.

Although not particularly shown, the sample stage 100 and the like are housed inside a vacuum chamber (not shown), and under a desired degree of vacuum, the semiconductor substrate 1 is irradiated with the ion beam 102 (ion implantation), and a halogen lamp is used. Heat treatment by step 105 is performed.

An example of a method for manufacturing a semiconductor device using an ion implantation apparatus having such a configuration will be described below.

First, the semiconductor substrate l is loaded onto the sample stage 100 and cooled to a low temperature by the coolant 104 flowing inside the sample stage 100. Then, while rotating the sample stage 100,
Ion implantation into the semiconductor substrate 1 at a low temperature is performed for a predetermined period of time, and a desired amount of a desired impurity element is introduced into the semiconductor substrate 1.

Immediately after this ion implantation operation is completed, the halogen lamp 105 is turned on, and the semiconductor substrate 1 is irradiated with a hot ray of 1° 5a to rapidly raise the temperature to 600'C or more.

Here, FIGS. 2(a) and 2(b) are examples of measurement results when the manufacturing method of this example is applied to the formation of a buried doped layer of a semiconductor element formed on a semiconductor substrate l.

That is, in the case of this embodiment, a semiconductor substrate 1 made of p-type silicon with a plane orientation (100) and a resistivity of 10Ω (2) is
Under the cooling temperature of -150℃, acceleration energy 2MeV,
Phosphorus (P) ions were implanted under the conditions of 1X10 ion/aIr, and immediately after the implantation, heat treatment was performed at 900° C. for 1 minute. Figure (a) shows the P concentration distribution in the depth direction immediately after implantation, and Figure (b) shows the distribution of crystal defect density in the depth direction determined from the etch bit density measurement by Seco etching. .

In the same figure (b), a measurement line 5 shows the case where the substrate temperature at the time of implantation is room temperature, and a measurement line 6 shows the case where the substrate temperature is 1150°C.
This is the case where the implantation was performed at a temperature of -150°C, and then the temperature was returned to room temperature, the ion implantation device was taken out, and the heat treatment was performed.As mentioned above, the measurement line 7 indicates that the halogen lamp was immediately This shows the case of this example in which the heating was performed rapidly by the heating method No. 105.

As shown in the figure, the crystal defect density near the range and in the region deeper than the range is the same in the case of conventional low-temperature implantation and in the case of this example, and is 1/1/2 that in the case of implantation at room temperature. 10'. On the other hand, when compared in a region shallower than the range, in the case of conventional low-temperature implantation, the reduction was only 115 compared to that at room temperature, whereas in the case of this example, it was 1/10
Etch bit density (residual crystal defect density) significantly below 0
or is decreasing. This is schematically shown in FIGS. 1(a) to (e).

As described above, according to the method for manufacturing a semiconductor device and the ion implantation apparatus of this embodiment, when a buried doped layer is formed by ion implantation into the semiconductor substrate 1, there are fewer defects 2 in the shallow region, and the formation of the semiconductor element is improved. A buried tope layer can be formed with a surface area suitable for.

[Example 2] FIGS. 4(a) and 4(b) show an example in which the method for manufacturing a semiconductor device of the present invention is applied to the formation of a pn junction diode.

That is, FIG. 3A is a cross-sectional view showing an example of the structure of the pn junction diode.

For a p-type silicon substrate 8 with a surface concentration of I x 10 ''/al, an acceleration energy of 80 keV and 5 x 10 ''
As (arsenic) ions were implanted under the conditions of ion/al, and the 04 layer 9 was formed by heat treatment. The ion implantation is performed by fixing the temperature of the silicon substrate 8 at a certain temperature in the range of -150°C to -200°C. After the ion implantation is completed, the heat treatment is performed inside the ion implantation device at a temperature of 900"0.1".
The test was carried out under conditions of 1 minute.

The shape of the pn junction is a rectangle of 2008 m x 200 μm, and each element is covered with a selective oxide film of 500 nm thick.
(Sift) to separate the elements.

Further, the surface of the diode is covered with an insulating protective film 10a, and an extraction terminal 10b is connected to the n+ layer 9 through a through hole opened at a position facing the center of the n+ layer 9.

FIG. 5B is a diagram showing an example of the relationship between the leakage current measured with a reverse applied voltage of 5 V and the cooling temperature of the silicon substrate 8 during implantation in the diode thus formed. The leakage current decreases significantly when the temperature of the silicon substrate 8 is -100°C or lower, and is -15°C.
It is known that when the temperature is set to 0° C., the amount is drastically reduced to about 1/20 of that when ion implantation is performed at room temperature.

According to the method for manufacturing a semiconductor device of this embodiment, the temperature of the silicon substrate 8 during ion implantation is kept below -100°C, and immediately after the implantation is completed, heat treatment is performed by heating the silicon substrate 8 to a temperature of 900″C. , a diode having a pn junction with extremely low leakage current can be manufactured.

Although not particularly shown, a part of the sample stage 100 on which the semiconductor substrate 1 is fixed, including the cooling structure, is made portable, and the semiconductor substrate 1 that has undergone ion implantation is transported to the outside while still in a low temperature state. It may be carried out and loaded into a desired heating device to perform activation of introduced impurities and recovery treatment of crystal defects.

[Example 3] Figures 5 (al and 'b) are cross-sectional views and performance diagrams of a vertical npn bipolar transistor manufactured by a method for manufacturing a semiconductor device and an ion implantation apparatus according to another example of the present invention. FIG. 6 is a diagram illustrating an example. FIG. 6 is a sectional view schematically illustrating an example of the configuration of the ion implantation apparatus of this embodiment.

The ion implantation apparatus of this third embodiment is configured so that the silicon substrate 8 held on the sample stage 100 is heated by the argon ion laser 106a.

That is, an optical system 107 and a swinging mirror 108 are interposed in the optical path of the argon ion laser 106a emitted from the laser source 106, and the entire surface of the silicon substrate 8 rotating together with the sample stage 100 is scanned by the argon ion laser 106a. (irradiation) enables rapid heat treatment.

Using such an ion implantation apparatus, a bipolar transistor having the cross-sectional structure shown in FIG. 5(a) was formed in the following manner.

That is, for a p-type silicon substrate 8 with a resistivity of 30Ω, an acceleration energy of 2.5 MeV and 3×101″ ions/
The buried sub-collector 11 was formed by P ion implantation under the conditions of cffl. Silicon substrate 8 during implantation
Temperature is -50℃~-200℃ 1 Heat treatment after implantation is as follows:
Immediately after implantation is completed in the chamber of the ion implanter,
This was performed by heating, for example, at 900° C. for 1 minute by irradiation with an argon ion laser 106a.

Thereafter, a vertical bipolar transistor having an emitter depth and a base width of 0.1 .mu.m each and an area of 2.times.3 .mu.m.sup.2 was fabricated using a well-known technique.

FIG. 2B shows the relationship between the rate of defective products in the vertical bipolar transistor manufactured in this manner and the temperature of the silicon substrate 8 during ion implantation. The rate of defective products was determined by determining that products with a current gain of 5θ or less or 200 or more when the collector current reached 1O-4 were considered defective.

In the case of this embodiment, the defective product incidence rate decreases as the temperature of the silicon substrate 8 during ion implantation decreases, and when the substrate temperature is -150°C, it is about 1150 compared to the case of implantation at room temperature. It is known that.

As described above, according to the semiconductor device manufacturing method and ion implantation apparatus of this embodiment, it is possible to significantly improve the reliability of operation of a bipolar transistor that uses ion implantation to form a buried collector.

Note that in the above description, an argon ion laser is used as a heating means, but heating may be performed by irradiation with an electron beam or microwave.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the semiconductor device is not limited to the diodes and bipolar transistors exemplified in the above embodiments, but may be other semiconductor elements.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, according to the method of manufacturing a semiconductor device according to the present invention, defects generated during ion implantation are stabilized by being left near room temperature by heating to a high temperature immediately after ion implantation in a low temperature state. Avoided. This provides the effect that defects can be easily recovered by heat treatment and residual defects can be reliably reduced.

Further, according to the method of manufacturing a semiconductor device of the present invention, -10
Since the semiconductor substrate is kept at a low temperature from the start of ion implantation at a low temperature below 0°C until the activation of the introduced substance by heating, the ion-implanted semiconductor substrate can be left at room temperature. do not have. This prevents defects generated during ion implantation from becoming stabilized by being left at room temperature, making it easier to recover defects through heat treatment, and reliably reducing residual defects. You can get some effect.

Further, according to the ion implantation apparatus of the present invention, ions are implanted while the semiconductor substrate is kept at a low temperature by the cooling means disposed on the sample stand, and immediately after the completion of the ion implantation, the semiconductor substrate is placed on the sample stand. It is possible to perform an operation of immediately heating the sample to a high temperature using a heating means while the sample is being held at a high temperature. This prevents defects generated during ion implantation from becoming stabilized by being left at room temperature, making it easier to recover defects through heat treatment, and reliably reducing residual defects. You can get some effect.

Further, according to the semiconductor device according to the present invention, claims 1 and 2
．． Since the semiconductor device is manufactured by the semiconductor device manufacturing method described in 3 or 4, it is possible to reduce product defects and improve operational reliability.

Further, according to the semiconductor device of the present invention, since it is manufactured using the ion implantation apparatus according to claim 5 or 6,
This has the effect of reducing product defects and improving operational reliability.

[Brief explanation of the drawing]

FIG. 1 (al to FC+ is a diagram schematically showing an example of the effects of the semiconductor device manufacturing method and ion implantation device according to an embodiment of the present invention in comparison with the case of the prior art; FIG. (a) and ('b) are diagrams schematically showing an example of the effects of the semiconductor device manufacturing method and ion implantation device, which are also an embodiment of the present invention, in comparison with the case of the prior art; FIG. 3 is a schematic cross-sectional view schematically showing an example of the configuration of the ion implantation apparatus of this embodiment, and FIGS. FIGS. 5(a) and 5(b) are explanatory views when applied to the formation of a pn junction diode. An explanatory diagram of a transistor; FIG. 6 is a cross-sectional view schematically showing an example of the configuration of the ion implantation apparatus of this embodiment; FIGS. 7(a) to (C) are It is an explanatory view schematically illustrating an example of the general effect when the above is applied.■...Semiconductor substrate, 2.3.4...Defect, 5.6.
7...Measurement line, 8...Silicon substrate, 9...n4
layer, 1O...selective oxide film, 11...embedded sub-collector, 100...sample stand, 100a...coolant channel,
101...Rotation axis, 102...Ion beam, 10
3...Beam deflector, 104...Refrigerant, 105...
・No10 Genrambu, 105a...Heat ray, 106...
・Laser source, 106a...Argon ion laser, 1
07...Optical system, lO8...Swinging mirror. In case of Example 1 2...Defect (t)) (C) Conventional low temperature implantation Impurity concentration - Figure 2 (G) ・(b) Figure 4 (b) Substrate 1 degree (''C)

Claims (1)

[Scope of Claims] 1. A method for manufacturing a semiconductor device in which a desired substance is introduced by ion implantation into a semiconductor substrate on which the semiconductor device is formed, the method comprising: implanting the ions while maintaining the temperature of the semiconductor substrate at -100°C or lower; A method for manufacturing a semiconductor device, comprising a first step of implanting, and a second step of instantaneously heating the semiconductor substrate to a temperature of 600° C. or higher immediately after the first step. . 2. The method of manufacturing a semiconductor device according to claim 1, wherein the heating of the semiconductor substrate is performed using a halogen lamp, a microwave, or an energy beam. 3. The time required for heating the semiconductor substrate to the temperature of 600° C. or higher from immediately after the completion of the ion implantation to the semiconductor substrate is 1.
3. The method of manufacturing a semiconductor device according to claim 1, wherein the manufacturing time is within minutes. 4. A method for manufacturing a semiconductor device in which a desired substance is introduced into a semiconductor substrate on which the semiconductor device is formed by ion implantation, the substance being introduced into the semiconductor substrate by the ion implantation from the start of the ion implantation process. A method of manufacturing a semiconductor device, characterized in that the temperature of the semiconductor substrate is maintained at -100° C. or lower until activation treatment by heating. 5. a sample stage that removably holds a semiconductor substrate, an ion beam forming means for irradiating the semiconductor substrate held on the sample stage with an ion beam of a desired substance, and disposed on a part of the sample stage; A cooling means for cooling the semiconductor substrate held on the sample stand to -100°C or lower, and a cooling means provided near the sample stand to cool the semiconductor substrate held on the sample stand to 600°C at any time. An ion implantation device characterized by comprising a heating means for instantaneously heating to a temperature above. 6. The ion implantation apparatus according to claim 5, wherein the heating means is a halogen lamp, a microwave, or an energy beam. 7. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 1, 2, 3 or 4. 8. A semiconductor device manufactured using the ion implantation apparatus according to claim 5 or 6.