JP2005072434A - Film forming method of semiconductor substrate and semiconductor device manufactured by employing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film forming method of a semiconductor substrate capable of forming a thick film thickness without the need for heat treatment for a long time, and to provide a semiconductor device manufactured by employing the method. <P>SOLUTION: A resist film on the surface of the semiconductor substrate is removed, surface treatment to promote growing of a film formed on the surface of the semiconductor substrate is carried out at a prescribed temperature, and thereafter the film is formed on the surface of the semiconductor substrate at a temperature higher than the prescribed temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for forming a semiconductor substrate and a semiconductor device manufactured using the method.

  Conventionally, in a semiconductor device, an oxide film is formed as a protective film or an insulating film on the surface of a semiconductor substrate.

  This oxide film is obtained by removing the resist film used in the dry etching process or lithography process by ashing at a predetermined temperature, and then thermally oxidizing the surface of the semiconductor substrate at a temperature increased from the predetermined temperature. (For example, refer to Patent Document 1).

  As the method, first, the resist film is removed by making an oxygen (O) radical collide with the resist film remaining on the surface of the semiconductor substrate at a temperature of about 200 ° C. in an ashing apparatus. Thereafter, the temperature inside the oxidation furnace was raised to about 1000 ° C., and the surface of the semiconductor substrate was thermally oxidized to form an oxide film.

Since the oxide film thus formed is formed for the purpose of insulating and protecting the semiconductor device, it has been necessary to form the film so as to have a predetermined thickness or more.
Japanese Patent Laid-Open No. 11-102906

  However, in the conventional film formation method described above, the oxide film cannot be formed thick unless the surface of the semiconductor substrate is thermally oxidized for a long time. For this reason, the semiconductor substrate is distorted by being exposed to a high temperature for a long time, and the yield of the product is lowered.

  In addition, when thermal oxidation is performed over a long period of time, impurities generated when the resist film is removed are mixed into the oxide film and contaminate the oxide film, so the interface characteristics between the semiconductor substrate and the oxide film Became unstable, and the insulating properties of the oxide film were deteriorated.

  Therefore, in the present invention according to claim 1, after removing the resist film on the surface of the semiconductor substrate, surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under a predetermined temperature, The film was formed on the surface of the semiconductor substrate under a temperature higher than a predetermined temperature.

  In the present invention according to claim 2, in the surface treatment, the film thickness to be formed is changed by changing the surface treatment time.

  In the present invention according to claim 3, the surface treatment time is set to 20 minutes or longer.

  In the present invention according to claim 4, the resist film is removed and the surface treatment is performed by irradiating the surface of the semiconductor substrate with plasma.

  Further, in the present invention according to claim 5, after removing the resist film on the surface of the semiconductor substrate, surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under a predetermined temperature, The production was performed by forming a film on the surface of the semiconductor substrate under a temperature higher than a predetermined temperature.

  In the present invention according to claim 1, after removing the resist film on the surface of the semiconductor substrate, a surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed at a predetermined temperature, and then the predetermined temperature is reached. Since the film was formed on the surface of the semiconductor substrate at a higher temperature, the film thickness can be increased without performing a long-time heat treatment, so that the semiconductor substrate can be prevented from being distorted, It is possible to prevent the insulating properties of the film from deteriorating.

  Further, in the present invention according to claim 2, since the surface treatment is to change the film thickness to be formed by changing the surface treatment time, the desired thickness can be obtained only by changing the surface treatment time. This film can be easily formed.

  In the present invention according to claim 3, since the surface treatment is performed for a surface treatment time of 20 minutes or longer, the growth of a film formed on the surface of the semiconductor substrate can be surely promoted by this surface treatment. .

  In the present invention according to claim 4, since the resist film is removed and the surface treatment is performed by irradiating the surface of the semiconductor substrate with plasma, the ashing apparatus used for removing the resist film is used as it is. Since the surface treatment can be performed, it is not necessary to make a new capital investment to perform the surface treatment, and an increase in manufacturing cost of the semiconductor device can be prevented.

  Further, in the present invention according to claim 5, after removing the resist film on the surface of the semiconductor substrate, surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under a predetermined temperature, Since manufacturing is performed by forming a film on the surface of a semiconductor substrate at a temperature higher than a predetermined temperature, deformation of the semiconductor substrate due to long-time heat treatment can be prevented, so that a semiconductor device with a low incidence of defective products is obtained. And the yield of products can be improved. Further, a semiconductor device having a film with excellent insulating characteristics that is not adversely affected by heat treatment for a long time can be obtained.

  The semiconductor device according to the present invention is manufactured as follows.

  First, the resist film formed on the surface of the semiconductor substrate is irradiated with plasma using an ashing device to remove the resist film, thereby exposing the surface of the semiconductor substrate.

  Thereafter, a surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under substantially the same process conditions as when the resist film was removed.

  In this surface treatment, the ashing apparatus from which the resist film has been removed is used as it is, and the exposed surface of the semiconductor substrate is irradiated with plasma for a predetermined time without removing the semiconductor substrate from the ashing apparatus. This surface treatment is performed at a temperature lower than the temperature in the next film formation process.

  By causing the plasma to collide with atoms on the surface of the semiconductor substrate by this plasma irradiation, it is considered that atoms near the surface of the semiconductor substrate are in an active state in which they are likely to combine with atoms in a predetermined process gas during film formation.

  Then, a film is formed on the surface of the semiconductor substrate by reacting atoms in the vicinity of the surface of the semiconductor substrate with atoms in a predetermined process gas at a temperature of 1000 ° C., for example.

  As described above, the film provided in this semiconductor device does not require long-time heat treatment to form a thick film, so there is no possibility that the semiconductor substrate is deformed during film formation, and the incidence of defective products. The semiconductor device can be low.

  Furthermore, since the impurities generated when the resist film is removed do not enter the film during the film formation, the interface characteristics between the semiconductor substrate and the film are stable and the semiconductor device has excellent insulating characteristics. Can do.

  Also, the surface treatment is performed by irradiating the surface of the semiconductor substrate with plasma continuously using the same apparatus after removing the resist film using a conventional ashing apparatus for removing the resist film. Therefore, since it is not necessary to make a new capital investment for performing the surface treatment, it is possible to prevent an increase in the manufacturing cost of the semiconductor device.

  Hereinafter, a method for forming a semiconductor substrate according to the present invention will be specifically described with reference to the drawings. In the following description, a method for forming an oxide film on the surface of a semiconductor substrate will be described. However, the present invention is not limited to this, and another film, for example, a nitride film is formed on the surface of a semiconductor substrate. It can also be applied to.

  First, as shown in FIG. 1A, a semiconductor (Si) substrate 1 having a resist film 2 formed on the surface is placed inside an ashing apparatus.

  Thereafter, oxygen (O 2) flowing into the ashing device is turned into plasma inside the ashing device to generate oxygen radicals 3.

  Next, the temperature in the ashing apparatus is set to about 200 ° C., and as shown in FIG. 1B, the oxygen radical 3 and the resist film 2 are reacted for about 20 minutes. The resist film 2 is usually a solid composed of oxygen (O), carbon (C), and hydrogen (H), and reacts with the oxygen radical 3 to form a gas composed of CO2, O2, and H2O. Removed.

  In this way, as shown in FIG. 1C, the resist film 2 is completely removed, and the surface of the Si substrate 1 is exposed.

  Next, the surface treatment for promoting the growth of the film formed on the surface of the Si substrate 1 is performed for about 40 minutes by leaving the surface of the Si substrate 1 in an active state while keeping the process conditions in the ashing apparatus as it is. This surface treatment is performed by irradiating the exposed surface of the Si substrate 1 with oxygen radicals 3 as shown in FIG.

  By doing so, a surface active region 4 is formed in the vicinity of the surface of the Si substrate 1 as shown in FIG.

  At this time, the Si atoms in the surface active region 4 are in an active state in which they are easily bonded to O atoms during thermal oxidation.

  As described above, the surface treatment is continuously performed using an ashing apparatus for removing the resist film 2.

  Next, the Si substrate 1 is moved to an oxidation furnace, and the Si substrate 1 is heated to about 1000 ° C. in an oxygen (O 2) atmosphere and thermally oxidized for a predetermined time, thereby, as shown in FIG. An oxide film (SiO 2 film) 5 is formed on the surface of 1.

  At this time, as described above, since Si atoms near the surface of the Si substrate 1 are in an active state, they are quickly bonded to O atoms in the O 2 atmosphere. Therefore, a thicker oxide film 5 can be formed even if thermal oxidation is performed for the same period of time as before.

  FIG. 2 shows the relationship between the thickness of the oxide film 5 formed by this thermal oxidation and the surface treatment time.

  As can be seen from FIG. 2, when thermal oxidation is performed for a predetermined time without surface treatment (when the surface treatment time is 0 minute), an oxide film 5 having a thickness of about 9.7 nm is formed. On the other hand, when the surface treatment is performed for about 40 minutes and then thermal oxidation is performed for the same predetermined time, the oxide film 5 having a thickness of about 10.9 nm is formed.

  In this way, when the surface treatment is performed, the film thickness is formed to be about 12% thick even though thermal oxidation is performed for the same time as compared with the case where the surface treatment is not performed. Can do.

  In other words, when the oxide film 5 having the same film thickness is formed, it is possible to shorten the thermal oxidation treatment time of the Si substrate 1 by performing the surface treatment.

  Therefore, deformation of the Si substrate 1 due to long-time thermal oxidation can be prevented, the generation rate of defective products can be reduced, and the yield of products can be improved.

  Furthermore, the impurities generated when the resist film 2 is removed are not mixed into the oxide film 5 and the interface characteristics between the Si substrate 1 and the oxide film 5 are stabilized, so that the insulating characteristics are excellent. An oxide film 5 can be formed.

  Further, in the conventional film forming method, the change in the thickness of the oxide film 5 to be formed depends only on the time for performing the thermal oxidation, whereas in the present invention, the change in the thickness of the oxide film 5 to be formed is as follows. The change also depends on the time for performing the surface treatment, as shown in FIG.

  Therefore, when the oxide film 5 is formed thick, the film thickness can be increased by extending the surface treatment time, and deformation of the Si substrate 1 or deterioration of the film quality of the oxide film 5 due to prolonged thermal oxidation. The oxide film 5 having a desired thickness can be easily formed without considering the above.

  Here, as shown in FIG. 2, when performing the surface treatment, the surface treatment of 20 minutes or less makes the surface of the Si substrate 1 less likely to be in an active state, and the change in the thickness of the oxide film 5 corresponding to the surface treatment time is small. Therefore, it is preferable to perform the surface treatment for at least 20 minutes.

  In particular, when the surface treatment is performed for 30 minutes or more, as shown in FIG. 2, the change in the thickness of the oxide film 5 corresponding to the surface treatment time appears more significantly. More preferably.

It is explanatory drawing which shows the film-forming method of the semiconductor substrate which concerns on this invention. It is a graph which shows the relationship between surface treatment time and an oxide film thickness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Resist film 3 Oxygen radical 4 Surface active region 5 Oxide film

Claims (5)

  After removing the resist film on the surface of the semiconductor substrate, surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under a predetermined temperature, and then the temperature is higher than the predetermined temperature. A method for forming a semiconductor substrate, comprising forming a film on a surface of the semiconductor substrate.   The method of forming a semiconductor substrate according to claim 1, wherein the surface treatment changes a film thickness to be formed by changing a surface treatment time.   3. The method of forming a semiconductor substrate according to claim 1, wherein the surface treatment has a surface treatment time of 20 minutes or more.   4. The method for forming a semiconductor substrate according to claim 1, wherein the resist film is removed and the surface treatment is performed by irradiating the surface of the semiconductor substrate with plasma.   After removing the resist film on the surface of the semiconductor substrate, surface treatment for promoting the growth of the film formed on the surface of the semiconductor substrate is performed under a predetermined temperature, and then the temperature is higher than the predetermined temperature. A semiconductor device manufactured by forming a film on a surface of a semiconductor substrate.

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