JPH0629234A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To achieve that impurities are hard to be left on a treated surface, that the treated surface is hard to damage, that the impurities are hard to diffuse and that an element characteristic is hard to deteriorate by a method wherein the following are executed simultaneously or alternately: a process wherein a substrate to be treated is heated for a short time by a rapid thermal annealing method; and a process wherein the beam of the constituent substance of the substrate to be treated is irradiated. CONSTITUTION:A substrate holder 11 has a shape which sandwiches edges of a substrate 12 in such a way that the surface on the side of an element formation region on the substrate 12 and the rear on its opposite side are not covered; the substrate 12 is arranged in such a way that its surface is faced downward; an infrared lamp 13 which can irradiate the rear is provided. Three X three pieces of molecular-beam cells 14 are arranged in a direction perpendicular to the surface of the substrate 12; the surface of the substrate 12 can be irradiated uniformly with molecular beams. The molecular beams are charged with high-purity Si. The Gi substrate 12 is moved between the infrared lamp 13 and the molecular-beam cells 14; its surface temperature is held at about 300 deg.C by the infrared lamp 13; the temperature of the molecular-beam cells 14 is raised to about 1400 deg.C; the temperature of the substrate 12 is raised and it is lowered immediately after the molecular beams have been irradiated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, it can be applied to a semiconductor crystal manufacturing technique and a surface treatment method for a substrate such as silicon used in an electronic device manufacturing process. The present invention relates to a method for manufacturing a semiconductor device, which can prevent impurity residues, damages, and the like from easily occurring on a processed surface when a natural oxide film on a substrate to be processed is removed, and prevent deterioration of element characteristics.

Recently, DRA of 256Mb or 1Gb class
In order to realize a ULSI integrated circuit such as M, the research and development of its basic technology are being actively conducted. In this class of integrated circuit, the minimum processing dimension rule is 0.3 μm or less, which is extremely small, and in addition, in each process, high quality as well as low temperature is required. Moreover, with the demand for higher integration of elements, the processing steps have changed significantly.

[0003]

2. Description of the Related Art FIG. 7 is a diagram showing the adverse effect of a natural oxide film on the surface of silicon on the basic structure of a device. Figure 7
As shown in (a), a natural oxide film is formed on the surface of the silicon substrate 31.
SiO ₂ insulating film 33 and poly-Si wiring layer with 32
When the 34 are sequentially formed, SiO ₂ insulating film 33 gas SiO ₂ insulating film 33 and the poly-Si wiring layer 34, impurities are diffused
In addition, the film quality of the poly-Si wiring layer 34 is deteriorated, and breakdown characteristics and the like are likely to occur, so that element characteristics are easily deteriorated.

[0004] Figure 7 (b), the silicon substrate 31 surface in a natural state where the oxide film 32 is caused to sequentially formed SiO ₂ insulating film 33 and the Al wiring layer 34 ,, SiO ₂ insulating film 33 And gases, impurities, etc. diffuse into the Al wiring layer 34, and the film quality of the SiO ₂ insulating film 33 and the Al wiring layer 34 deteriorates.
Element characteristics such as defects induced in the Al wiring layer 34 are likely to deteriorate.

Further, as shown in FIG. 7 (c), SiO ₂
A poly-Si wiring layer 34 is formed in a state where the natural oxide film 32 is formed on the surface of the silicon substrate 31 in the opening 33a formed in the insulating film 33, and a natural oxide film is further formed on the surface of the poly-Si wiring layer 34. If the SiN insulating film 35 is formed in this state, gas, impurities, etc. diffuse into the poly Si wiring layer 34 and the SiN insulating film 35, and the film quality of the poly Si wiring layer 34 and the SiN insulating film 35 deteriorates.
Contact characteristics are likely to occur between the silicon substrate 31 and the poly-Si wiring layer 34, or the capacitance of the capacitor is lowered to easily cause defects, resulting in deterioration of element characteristics. The problem shown in FIG. 7 becomes remarkable especially in the process of 0.3 μm level ULSI integrated circuits.

As described above, if the next layer is formed in the state where the natural oxide film is formed, the device characteristics will be deteriorated.
Conventionally, before forming a film, a surface treatment is performed by argon sputter etching, hydrogen plasma etching, fluorine radical etching, or the like to remove stains on the natural oxide film.

[0007]

However, in the above-described conventional method for manufacturing a semiconductor device, the surface treatment is performed by argon sputter etching, hydrogen plasma etching, fluorine radical etching, or the like. Impurities tend to remain, and if the next layer is formed with impurities remaining, the impurities will diffuse into the formed film, and as a result, the quality of the formed film will deteriorate and the device characteristics Has a problem that it is easily deteriorated. Further, since the surface treatment is performed by etching, there is a problem that the treated surface is easily damaged. If the surface is damaged, the surface morphology may be deteriorated, or if the underlying layer has a diffusion layer, the diffusion layer may be etched.

For this reason, in order to solve the problem that impurities remain on the treated surface and damage the treated surface, conventionally, the silicon substrate is heated at a high temperature of about 1000 ° C. using a heating furnace. Then, a method is known in which the SiO ₂ natural oxide film is removed by irradiating with a Si beam for more than 10 seconds. When removing the SiO ₂ natural oxide film without pretreatment on the silicon substrate, the substrate temperature should be about
A clean substrate surface can be obtained by setting the temperature to 1000 ° C. and irradiating the Si beam for 10 seconds or more.

However, in this method, since the temperature is raised in the furnace to raise the substrate temperature to a high temperature of 1000 ° C., it takes a long time to raise the temperature. For this reason,
Due to this high temperature holding for a long time, diffusion of impurities such as the diffusion layer in the element formation region occurs, and as a result, similar to the above, there is a problem that element characteristics are deteriorated due to impurity diffusion.

Therefore, according to the present invention, when the natural oxide film on the surface of the substrate to be processed is removed, it is possible to prevent impurities from remaining on the surface to be processed, and to prevent damage to the surface to be processed, and further It is an object of the present invention to provide a method for manufacturing a semiconductor device that can prevent diffusion and prevent deterioration of element characteristics.

[0011]

In order to achieve the above-mentioned object, a method of manufacturing a semiconductor device according to the present invention uses an RTA for a substrate to be processed.
A heating step of heating for a short time by a (Rapid Thermal Annealing) method and a beam irradiation step of irradiating the substrate to be processed with a beam of a constituent material of the substrate to be processed are performed at the same time or alternately at least once. The step of performing a surface treatment on the substrate to be processed is included.

The substrate to be processed according to the present invention includes Si and Ga.
Substrates made of As, InP and the like can be cited, and the beams of the constituent material of the substrate to be treated therefor can be beams of Si, As, P and the like. In addition, examples of heating by the RTA method include infrared irradiation heating. In the present invention, the beam irradiation is preferably carried out by a plurality of molecular beam cells, in which case a single molecular beam cell can be obtained by arranging the molecular beam cells appropriately and evenly with respect to the substrate to be treated. It is possible to irradiate the substrate to be processed with a more even distribution than in the case of.

In the present invention, when the heating step and the beam irradiation step are performed at the same time, for example, infrared rays or the like are heated from the back surface of the substrate to be processed (the surface opposite to the element formation region) to perform the beam irradiation. The heating may be performed from the surface of the substrate to be processed (the surface on the side of the element formation region), and when the heating step and the beam irradiation step are alternately performed, heating such as infrared irradiation and beam irradiation are performed on the surface of the substrate to be processed. It should be done alternately from. In the former case, the device system can be simplified and the surface can be easily treated as compared with the latter case. In the latter case, both steps can be performed from the front surface side of the substrate to be processed, so that the variation in the substrate surface temperature can be made smaller than in the former case.

In the present invention, wiring such as Al and SiO
It can be preferably applied to a pretreatment before forming an insulating film such as _{2 and the} like, and particularly preferably to a pretreatment step in a multi-chamber apparatus having a plurality of chambers such as a CVD or sputtering apparatus.

[0015]

Since the substrate temperature is conventionally raised in the furnace as described above, it takes a long time to reach the target temperature of 1000 ° C. as shown in FIG. Ten
Even if the natural oxide film can be removed by keeping the temperature of 00 ° C for only ten and a few seconds, the substrate is exposed to a high temperature for a long time of several minutes to several tens of minutes, which causes impurity diffusion and damage, and is practical. There was a problem.

On the other hand, since the RTA method is used in the present invention, as shown in FIG. 1B, it takes only a few seconds to raise the temperature to 1000 ° C., and the temperature can be lowered in a few seconds to several tens of seconds. Because it is good, the time to keep the substrate at a high temperature is much shorter than that in the case of using a conventional furnace. This can be said to be an equivalent process to the low temperature process because the process can be terminated before the influence of the diffusion of impurities appears. Therefore, problems such as damage and diffusion of impurities do not occur.

As described above, according to the present invention, the temperature of the substrate is raised for a short time by the RTA method so that the natural oxide film on the surface of the substrate can be easily removed.
The natural oxide film is physically removed by irradiating the same beam. As described above, since the beam of the constituent material of the substrate is irradiated, it is possible to prevent impurities residues from being easily generated on the treated surface. Even if the atoms (Si, etc.) of the substrate constituent substances remain on the processed surface, they are not impurities such as F in the case of conventional F etc. etching. There is no adverse effect. And
Since the natural oxide film, which has been heated and is in a state where it is easy to remove, is removed by beam irradiation, it is possible to prevent damage to the surface to be treated unlike in the case of conventional etching. Moreover, since the substrate temperature can be raised in a short time by the RTA method, it can be more difficult to occur than in the case of the high temperature time in the conventional furnace.

Needless to say, the natural oxide film cannot be removed only by raising the temperature of the substrate by the RTA method for a short time. Also, if the substrate is irradiated with a beam,
For example, with a Si beam at room temperature, it goes without saying that the natural oxide film cannot be removed but only Si is deposited.

[0019]

(Embodiment 1) FIG. 2 is a schematic view showing the structure of a multi-chamber apparatus according to Embodiment 1 of the present invention. In FIG. 2, each chamber is maintained in an ultrahigh vacuum or a high vacuum and is partitioned by a gate valve 1. The chambers are the CVD chamber 2, the sputtering chambers 3 and 4, the preparation chamber 5, and the UHV (Ultra High Vacuum, Ultra High Vacuum) processing chamber 6.
The wafer can be moved between the chambers with the preparation chamber 5 as the center.

Next, FIG. 3 is a plan view and a cross-sectional schematic view showing the structure of the surface treatment apparatus installed in the UHV treatment chamber 6 which is maintained in an ultrahigh vacuum of the order of 10 ^-10 Torr. In FIG. 3, reference numeral 11 denotes a substrate holder for holding the substrate 12, and the substrate holder 11 does not cover the surface of the substrate 12 on the element formation region side and the back surface on the opposite side thereof.
It has a shape sandwiching the edges of 12 and is arranged so that the surface of the substrate 12 faces downward. An infrared lamp 13 is provided as a heater that can radiate infrared rays from the back of the substrate 12. Also, 3 × in the vertical direction of the surface of the substrate
Three molecular beam cells 14 are arranged so that the surface of the substrate 12 can be uniformly irradiated with the molecular beam. In the molecular beam cell 14,
High-purity Si is charged.

First, the Si substrate 12 is moved from the preparatory chamber 5 kept in a high vacuum to the UHV processing chamber 6. Then S
The i substrate 12 is moved between the infrared lamp 13 and the molecular beam cell 14, and the surface temperature of the substrate 12 is kept at 300 ° C. by the infrared lamp 13. Meanwhile, the temperature of the molecular beam cell 14 is raised to about 1400 ° C. with the shutter closed. This molecular beam cell 14
Is set so that the rate of molecular beam growth on the surface of the substrate 12 is about 1Å / sec. After that, the surface temperature of the substrate 12 is increased to reach 1000 ° C and at the same time the molecular beam cell is reached.
Open 14 shutters for 15 seconds. And molecular beam cell 14
The substrate 12 temperature is lowered at the same time when the shutter of is closed. The temperature of the substrate 12 is lowered to 300 ° C. in about 20 seconds so that the temperature does not fall rapidly. This allows the substrate
It is possible to remove several tens of liters of natural oxide film on the 12th surface and obtain a clean substrate 12 surface. Here, FIG. 4 shows changes in the substrate surface temperature with time when this method is used.

Then, the substrate 12 on which a clean surface is obtained is returned to the preparation chamber 5 again, moved to the CVD chamber 2, the sputtering chamber 3 and the sputtering chamber 4 and subjected to a predetermined treatment. As described above, in the present embodiment, a clean substrate 12 surface can be obtained by adding a surface treatment device capable of extremely clean surface treatment to a multi-chamber device composed of an ultra-high vacuum or a high vacuum, and there is a risk of contamination. Instead, it can be moved to the next chamber and subjected to the next predetermined treatment, so that a semiconductor device having excellent characteristics could be manufactured. Since the high-purity Si molecular beam is irradiated from the molecular beam cell 14, there are no impurities other than Si and no impurities remain on the substrate 12. Since a plurality of molecular beam cells 14 are used, the substrate 12 is uniformly irradiated with the molecular beam, and even if an 8-inch wafer is used, the surface treatment can be performed evenly.
Further, since the RTA method using the infrared lamp 13 is used to raise the temperature of the substrate 12, the high temperature keeping time is as short as several tens of seconds, diffusion of impurities does not occur, and there is no damage.

(Embodiment 2) In this embodiment, the same multichamber device as that of the first embodiment will be described. FIG. 5 is a plan view and a cross-sectional schematic view showing the configuration of a surface treatment apparatus installed in a UHV treatment chamber 6 which is a vacuum chamber of a vacuum apparatus which is maintained at an ultrahigh vacuum of 10 ⁻¹⁰ Torr level. In FIG. 5, the same reference numerals as those in FIG. 3 indicate the same or corresponding portions, and 11a is a substrate holder for holding the substrate 12, and this substrate holder 11a holds the substrate 12 so that the surface of the substrate 12 faces downward. It has a cross shape that can hold one sheet, and it is designed to rotate about its center. Then, under the substrate holder 11a, it is equally divided into eight directions about the axis as shown in FIG.
The loader 21, the infrared lamp 13a, the molecular beam cell 14a, the infrared lamp 13b, the molecular beam cell 14b, the infrared lamp 13c, the molecular beam cell 14c, and the unloader 22 are arranged in this order from the preparation chamber 5 direction. Infrared lamps here 13a-13c
Are arranged so as to illuminate the surface of the substrate 12, respectively. The molecular beam cells 14a to 14c are arranged at 3 × 3 in one place so that the surface of the substrate 12 is uniformly irradiated with the molecular beam. High-purity Si is charged in the molecular beam cells 14a to 14c. The loader 21 can attach the substrate 12 moved from the preparation chamber 5 to the cross-shaped substrate holder 11a, and the unloader 22 can move the processed substrate 12 to the preparation chamber 5. It has a simple structure.

First, the substrate 12 is moved from the preparatory chamber 5 which is kept in a high vacuum to the UHV processing chamber 6. At that time, the substrate 12
Is attached to the substrate holder 11a by the loader 21. Then, the substrate 12 attached to the substrate holder 11a
The substrate holder 11a rotates and moves onto the infrared lamp 13a so that the surface temperature of the substrate 12 is maintained at 300 ° C. Meanwhile, the temperature of the molecular beam cell 14a is raised to about 1400 ° C. The temperature of the molecular beam cell 14a is set so that the molecular beam growth rate on the surface of the substrate 12 is about 1Å / sec. The surface of the substrate 12 is heated to 1200 ° C. on the infrared lamp 13a.
As soon as the surface temperature of the substrate 12 reaches 1200 ° C, the molecular beam cell 14a
It moves up and the molecular beam is irradiated for about 5 seconds, and the shutter closes. Meanwhile, the next substrate 12 is attached to the substrate holder 11a. When the shutter is closed, the substrate 12 is a molecular beam cell 14
Move up b. When the surface temperature of the next substrate 12 reaches 300 ° C, the surfaces of the first substrate 12 and the next substrate 12 are heated to 1200 ° C. When the surface temperature of the substrate 12 reaches 1200 ° C., it immediately moves to the next molecular beam cell and the molecular beam is irradiated for about 5 seconds.
This operation is performed for one rotation, and the substrate 12 is returned to the preparation chamber 5 by the loader 21. The irradiation time of the molecular flow from the molecular beam cells 14a to 14c is set to be 10 seconds to 15 seconds in total. Further, the cross-shaped substrate holder 11a rotates to suit each operation. Then, when the substrate 12 goes around once,
It is possible to remove dozens of natural oxide films on the surface of the substrate 12,
A clean substrate 12 surface can be obtained. Here, FIG. 6 shows changes in the substrate surface temperature with respect to changes with time when this method is used.

Then, the substrate 12 on which a clean surface is obtained is returned to the preparation chamber 5 again, moved to the CVD chamber 2, the sputtering chamber 3 and the sputtering chamber 4, and subjected to a predetermined treatment. As described above, in the present embodiment, a clean substrate 12 is obtained by adding a surface treatment apparatus capable of extremely clean surface treatment to a multi-chamber apparatus consisting of ultra-high vacuum or high vacuum.
Since the surface is obtained and there is no fear of contamination, it can be moved to the next chamber and the next predetermined treatment can be performed, so that a semiconductor device having excellent characteristics could be manufactured.
Since the high-purity Si molecular beam is irradiated from the molecular beam cells 14a to 14c, there are no impurities other than Si and no impurities remain on the substrate 12. Since a plurality of molecular beam cells are used, the substrate 12 is uniformly irradiated with the molecular beam, and even if an 8-inch wafer is used, surface treatment can be performed evenly. In this embodiment, since the infrared lamps 13a to 13c and the molecular beam cells 14a to 14c can be alternately arranged on the circumference and the treatment can be applied to the substrate 12 one after another, the surface treatment can be performed extremely efficiently. it can. Further, since the RTA method using the infrared lamps 13 to 13c is used to raise the temperature of the substrate 12, the time kept at high temperature is as short as several tens of seconds, diffusion of impurities does not occur, and there is no damage.

[0026]

According to the present invention, when the natural oxide film on the surface of the substrate to be processed is removed, it is possible to prevent impurities from remaining on the processed surface and to prevent damage to the processed surface. Moreover, there is an effect that it is possible to make it difficult to cause impurity diffusion and to make it difficult to cause deterioration of element characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in a substrate surface temperature with respect to time when a substrate is heated using a conventional furnace and when the substrate is heated using an RTA method of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a multi-chamber apparatus according to the first embodiment of the present invention.

FIG. 3 is a plan view and a cross-sectional schematic view showing a configuration of a surface treatment apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing changes in the substrate surface temperature with time according to Example 1 of the present invention.

5A and 5B are schematic plan and sectional views showing the configuration of a surface treatment apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram showing changes in the substrate surface temperature with time according to Example 2 of the present invention.

FIG. 7 is a diagram showing an adverse effect of a natural oxide film on a silicon surface on a basic structure of a device.

[Explanation of symbols]

 1 Gate Valve 2 CVD Room 3, 4 Sputtering Room 5 Preparation Room 6 UHV Processing Room 11, 11a Substrate Holder 12 Substrates 13, 13a-13c Infrared Lamp 14, 14a-14c Molecular Beam Cell 21 Loader 22 Unloader

Claims (7)

[Claims] 1. A substrate to be processed is a RTA (Rapid Thermal An
by simultaneously performing a heating step of heating for a short time by a (nealing) method and a beam irradiation step of irradiating the substrate to be processed with a beam of a constituent material of the substrate to be processed, or alternately performing at least once. And a step of performing a surface treatment on the substrate to be processed. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the beam irradiation is performed by a plurality of molecular beam cells. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the heating is infrared irradiation heating. 4. When performing the heating step and the beam irradiation step at the same time, the infrared irradiation heating is performed from the back surface of the substrate to be processed, which is opposite to the element formation region, and the beam irradiation is performed to the elements of the substrate to be processed. The method for manufacturing a semiconductor device according to claim 3, wherein the process is performed from the surface on the formation region side. 5. When the heating step and the beam irradiation step are performed alternately, the infrared irradiation heating and the beam irradiation step are performed from the surface of the substrate to be processed on the element formation region side. The method for manufacturing a semiconductor device according to claim 3. 6. The method of manufacturing a semiconductor device according to claim 5, wherein the surface treatment step is a pretreatment before film formation. 7. The method for manufacturing a semiconductor device according to claim 6, wherein the pretreatment is pretreatment in a multi-chamber apparatus having a plurality of chambers.