JP2008218612A - Heat treatment temperature measuring method of semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a versatile measuring method of heat treatment temperature capable of measuring in a wider temperature range. <P>SOLUTION: The method of measuring heat treatment temperature of a semiconductor substrate includes an impurity implanting process in which a dopant impurity is implanted into a surface part of a semiconductor substrate, a low resistive region formation process in which a low resistive region is formed at the surface part of the semiconductor substrate by heat treatment to the substrate, a crystal defect formation process in which an ion is implanted in the low resistive region to form a crystal defect therein so that the resistance of the low resistive region is increased, a heat treatment process in which, after the crystal defect formation process, the semiconductor substrate is put in a heat treatment device being held at a constant heat treatment temperature for a specified heat treatment period t1, a post-heat-treatment resistance measuring process in which post-heat-treatment resistance R1 of the low resistive region is measured after the heat treatment process, and a heat treatment temperature specifying process in which the heat treatment temperature in the heat treatment process is specified based on the relationship among heat treatment temperature, heat treatment period, and post-heat-treatment resistance, as well as the heat treatment period t1 and the post-heat-treatment resistance R1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for measuring a heat treatment temperature of a semiconductor substrate. Note that heat treatment in this specification refers to heating and holding a semiconductor substrate at a temperature equal to or higher than normal temperature. The heat treatment includes heating and holding the semiconductor substrate when processing the semiconductor substrate (for example, film formation, etching, etc.).

  At the time of manufacturing a semiconductor device, various processes are performed on the semiconductor substrate. In order to manufacture a semiconductor device having desired characteristics, it is necessary to perform each process under accurate conditions. In particular, the temperature at which the semiconductor substrate is held in each process (hereinafter referred to as heat treatment temperature) greatly affects the characteristics of the semiconductor device to be manufactured. Therefore, it is necessary to accurately control the heat treatment temperature. For this purpose, it is important to accurately measure the actual temperature of the semiconductor substrate during the heat treatment.

Patent Document 1 discloses a technique for measuring a heat treatment temperature in a heat treatment furnace using a semiconductor substrate in which crystal defects are formed by electron beam irradiation. In this technique, a semiconductor substrate on which crystal defects are formed is heat-treated in a heat treatment furnace. When the semiconductor substrate is held at a high temperature, the number of crystal defects in the semiconductor substrate is reduced and the resistance of the semiconductor substrate is lowered. From the resistance reduction rate, the temperature at which the semiconductor substrate is held in the heat treatment furnace is specified.
Patent Document 2 discloses a technique for measuring a heat treatment temperature of a semiconductor heat treatment apparatus using a semiconductor substrate on which a laminated film of Al and Ti is formed. In this technique, a semiconductor substrate on which an Al—Ti laminated film is formed is heat-treated with a semiconductor heat treatment apparatus. When the semiconductor substrate is held at a high temperature, the composition of the Al—Ti laminated film changes and the resistance of the Al—Ti laminated film increases. From the increase in resistance, the temperature at which the semiconductor substrate is held in the semiconductor heat treatment apparatus is specified.
Patent Document 3 discloses a technique for measuring a heat treatment temperature of a semiconductor heat treatment apparatus using a semiconductor substrate on which an amorphous layer is formed by ion implantation. In this technique, a semiconductor substrate on which an amorphous layer is formed is heat-treated with a semiconductor heat treatment apparatus. When the semiconductor substrate is held at a high temperature, the amorphous layer is recrystallized and the resistance of the amorphous layer is reduced. The temperature at which the semiconductor substrate is held in the semiconductor heat treatment apparatus is specified from the decrease in resistance.

JP-A-8-22963 JP-A-9-292285 JP 2000-208524 A

In the technique of Patent Document 1, a semiconductor substrate in which crystal defects are formed by electron beam irradiation is used. The electron beam irradiation apparatus is a special apparatus that is not used in the manufacturing process of a normal semiconductor device. Therefore, the technique of Patent Document 1 has low versatility. At a temperature of 200 ° C. or lower, the number of crystal defects formed on the semiconductor substrate is difficult to decrease, and the resistance of the semiconductor substrate hardly changes. At a temperature of 500 ° C. or higher, crystal defects are rapidly reduced. Therefore, in the technique of Patent Document 1, the measurable temperature is limited to 200 ° C to 500 ° C.
In the technique of Patent Document 2, a semiconductor substrate on which a laminated film of Al and Ti is formed is used. When this semiconductor substrate is heat-treated, Al and Ti diffuse in the semiconductor heat treatment apparatus. Therefore, after the heat treatment, the inside of the semiconductor heat treatment apparatus is contaminated. Therefore, this method can be used only when there is no problem even if Al and Ti remain in the semiconductor heat treatment apparatus, and the versatility is low. Moreover, since the temperature at which the composition change between Al and Ti occurs is 400 ° C. to 550 ° C., the temperature that can be measured by this method is limited to 400 ° C. to 550 ° C.
In the technique of Patent Document 3, a semiconductor substrate on which an amorphous layer is formed is used. Since the temperature at which the amorphous recrystallizes is 530 ° C. to 720 ° C., the temperature that can be measured by this method is limited to 530 ° C. to 720 ° C. The technique of Patent Document 3 has a problem that a relatively low temperature cannot be measured.

  The present invention has been made in view of the above circumstances, and provides a method for measuring a heat treatment temperature that is highly versatile and capable of measuring a wider temperature range.

The method for measuring a heat treatment temperature of a semiconductor substrate according to the present invention includes an impurity implantation step of implanting a dopant impurity into a surface portion of the semiconductor substrate, and activating the impurities implanted in the impurity implantation step by heat treating the semiconductor substrate. Low-resistance region formation process that forms a low-resistance region on the surface, and crystal defect formation that raises the resistance of the low-resistance region to a predetermined resistance by forming ions in the low-resistance region by implanting ions into the low-resistance region A heat treatment step in which the semiconductor substrate is put into a semiconductor heat treatment apparatus maintained at a constant heat treatment temperature after the crystal defect formation step and a predetermined heat treatment time t1, and a post-heat treatment resistance R1 in the low resistance region is measured after the heat treatment step. Post-heat treatment resistance measurement step, correlation between heat treatment temperature, heat treatment time and post-heat treatment resistance, heat treatment time t1, and post-heat treatment resistance From R1, it has a heat treatment temperature specifying step of specifying the heat treatment temperature in the heat treatment step.
When a semiconductor substrate in which crystal defects are formed in the low resistance region is heat-treated, the number of crystal defects in the low resistance region is reduced according to the heat treatment temperature and the heat treatment time t1, and the resistance of the low resistance region is lowered. Therefore, the post-heat treatment resistance R1 in the low resistance region is a resistance corresponding to the heat treatment temperature and the heat treatment time t1. Therefore, in the heat treatment temperature specifying step, the heat treatment temperature in the heat treatment step can be specified from the correlation between the heat treatment temperature, the heat treatment time, and the post heat treatment resistance, the heat treatment time t1, and the post heat treatment resistance R1.
The number of crystal defects in the low resistance region decreases even at room temperature. Therefore, according to this heat treatment temperature measurement method, a temperature equal to or higher than normal temperature can be measured. Moreover, this semiconductor substrate can be implemented using only an apparatus used for manufacturing a normal semiconductor device. Moreover, this semiconductor substrate can be comprised only with the substance used for manufacture of a normal semiconductor device. Therefore, this heat treatment temperature measurement method is very versatile.

In the heat treatment temperature measurement method described above, the number of crystal defects in the low resistance region is reduced even at room temperature. Therefore, the number of crystal defects is reduced between the formation of crystal defects and the start of the heat treatment process, and the resistance of the low resistance region is reduced. In some cases, the resistance decreases after the heat treatment due to the decrease in resistance.
In such a case, the above-described heat treatment temperature measurement method further includes a post-defect formation elapsed time measurement step of measuring a post-defect formation elapsed time t2 from the execution of the crystal defect formation step to the start of the heat treatment step. In the heat treatment temperature specifying step, the heat treatment step is calculated from the correlation between the heat treatment temperature, the heat treatment time, the post-heat treatment resistance and the elapsed time after defect formation, the heat treatment time t1, the post-heat treatment resistance R1, and the elapsed time after defect formation t2. It is preferable to specify the heat treatment temperature in.
According to such a configuration, the heat treatment temperature can be accurately measured even when the post-heat treatment resistance has a different value depending on the elapsed time after the defect formation after the crystal defect formation step until the heat treatment step is started. can do.

In the heat treatment temperature measurement method described above, it is preferable that the second conductivity type dopant impurity is implanted into the first conductivity type semiconductor substrate in the impurity implantation step.
According to such a configuration, when the resistance in the low resistance region is measured, current is prevented from flowing between the low resistance region and the semiconductor region outside the low resistance region, so that the resistance in the low resistance region can be accurately measured. Can be measured.

In the heat treatment temperature measurement method described above, in the post-heat treatment resistance measurement step, the post-heat treatment resistance R1 is measured at a plurality of measurement points in the low resistance region, and in the heat treatment temperature specifying step, each measurement in the heat treatment step is performed from the post-heat treatment resistance R1 at each measurement point. It is preferable to specify the heat treatment temperature at a point.
According to such a configuration, the distribution of the heat treatment temperature in the semiconductor substrate can be measured.

The heat treatment temperature measurement method described above further includes a separation layer formation step that is performed before the crystal defect formation step, and a separation layer removal step that is performed between the heat treatment step and the post-heat treatment resistance measurement step. In the step of forming a separation layer on the surface of the semiconductor substrate, in the crystal defect forming step, ions are penetrated through the separation layer and implanted into the surface portion of the semiconductor substrate, and in the heat treatment step, an insulating layer is formed on the separation layer. In the removing step, it is preferable to remove the insulating layer and the separation layer while keeping the semiconductor substrate at room temperature.
In this heat treatment temperature measurement method, the separation layer is formed on the surface of the semiconductor substrate in the separation layer forming step, and the insulating layer is formed on the separation layer in the heat treatment step. Therefore, the heat treatment temperature in the low resistance region is a temperature affected by the formation of the insulating layer. After the insulating layer is formed, the insulating layer and the separating layer are removed in the separation layer removing step, the post-heat treatment resistance measurement step is followed by measuring the post-heat treatment resistance R1 in the low resistance region, and the heat treatment temperature specifying step is specified. Therefore, according to this heat treatment temperature measurement method, the temperature (heat treatment temperature) of the semiconductor substrate when forming the insulating layer can be measured. Since the separation layer is formed before the crystal defect formation step, the measurement of the heat treatment temperature is not hindered by the separation layer formation step. Further, since the separation layer is removed at room temperature, the measurement of the heat treatment temperature is not hindered by the separation layer removal step.

The heat treatment temperature measuring method described above further includes a pre-heat treatment resistance measurement step of measuring the pre-heat treatment resistance R2 in the low resistance region immediately before performing the heat treatment step, and in the temperature specifying step, the heat treatment temperature, the heat treatment time, and the post-heat treatment resistance. The heat treatment temperature in the heat treatment step may be specified from the correlation between the heat treatment resistance and the pre-heat treatment resistance, the heat treatment time t1, the post-heat treatment resistance R1, and the pre-heat treatment resistance R2.
Even with such a configuration, the heat treatment temperature is accurately measured even when the post-heat treatment resistance becomes different depending on the elapsed time after the defect formation after the crystal defect formation step is performed until the heat treatment step is started. be able to.

The main features of the embodiments described in detail below are listed first.
First, the features of the semiconductor substrate manufacturing method of the first embodiment will be listed.
(Feature 1) In the impurity implantation step and the crystal defect formation step, ions of the same type are implanted.
(Feature 2) In the crystal defect formation step, a smaller amount of ions is implanted than in the impurity implantation step.
(Feature 3) In the impurity implantation step, ions of 1 × 10 ¹⁵ ions / cm ² or more are implanted.
(Feature 4) In the crystal defect forming step, ions of 1 × 10 ¹³ ions / cm ² or less are implanted.

(First embodiment)
Preferred embodiments of the present invention will be described below with reference to the drawings. In the first embodiment, the heat treatment temperature of the silicon substrate in the electric furnace is measured. FIG. 1 shows a flowchart of the heat treatment temperature measuring method of the present invention. FIG. 2 is a schematic cross-sectional view of the silicon substrate 10 used in the heat treatment temperature measurement method of FIG. The silicon substrate 10 is a p-type silicon substrate.

In step S2, phosphorus ions (n-type impurities) are implanted into the silicon substrate 10 from the upper surface 12 side. Phosphorus ions are implanted with energy remaining at the surface portion of the upper surface 12. Phosphorus ions are implanted at a concentration of 1 × 10 ¹⁵ ions / cm ² or more. As a result, a region in which a large number of phosphorus exists in the surface portion of the upper surface 12 is formed.
When phosphorus ions are implanted, crystal defects are formed on the surface portion of the upper surface 12. Crystal defects include interstitial silicon (silicon atoms at interstitial positions) generated in a silicon crystal by phosphorous ion implantation, vacancies (state where there are no atoms at lattice points), and the like.

In step S4, the silicon substrate 10 is heat treated. As a result, the phosphorus injected into the silicon substrate 10 in step S2 is activated, and a large number of carriers (electrons) are generated in the region where phosphorus is injected. That is, the region into which phosphorus is implanted becomes n-type. In addition, substantially all of the crystal defects formed in step S2 (crystal defects formed in the region implanted with phosphorus) are eliminated by the heat treatment. As a result, the region implanted with phosphorus in step S2 becomes the n-type low-resistance region 20. Since phosphorus is implanted into the surface portion of the upper surface 12 in step S2, the low resistance region 20 is formed in the surface portion of the upper surface 12 of the silicon substrate 10 as shown in FIG.
By controlling the conditions for implanting phosphorus ions in step S2 and the heat treatment conditions in step S4, the sheet resistance of the low resistance region 20 and the thickness of the low resistance region 20 can be accurately controlled. In this embodiment, the sheet resistance of the low resistance region 20 after step S4 is controlled to about 50Ω / sq. In the present embodiment, the thickness of the low resistance region 20 is controlled to about 5 μm. The thickness of the low resistance region 20 is preferably 5 μm or less.

In step S6, phosphorus ions are implanted into the silicon substrate 10 from the upper surface 12 side. Phosphorus ions are implanted with energy remaining in the low resistance region 20. In step S6, a smaller amount (low concentration) of phosphorus ions is implanted than in step S2. In this embodiment, phosphorus ions are implanted at a concentration of about 1 × 10 ¹³ ions / cm ² . When phosphorus ions are implanted, crystal defects are formed in the low resistance region 20 as in step S2. When crystal defects are formed, the sheet resistance of the low resistance region 20 increases. Hereinafter, the sheet resistance after step S6 is referred to as sheet resistance R0.
By controlling the conditions for implanting phosphorus ions in step S6, the sheet resistance R0 of the low resistance region 20 can be accurately controlled. In this embodiment, the sheet resistance R0 is adjusted to about 300Ω / sq.

  Crystal defects formed in the low resistance region 20 disappear with a predetermined probability even at room temperature (that is, about 25 ° C.). Therefore, after step S6, the number of crystal defects existing in the low resistance region 20 gradually decreases. That is, as shown in FIG. 4, the sheet resistance (sheet resistance Rt) of the low resistance region 20 decreases from the sheet resistance R0 with time.

  In step S8, an elapsed time t2 from the execution of step S6 to the execution of step S10 described later is measured. In the present embodiment, since step S10 is performed 3 hours after performing step S6, the elapsed time t2 is 3 hours.

  In step S10, the silicon substrate 10 is heat-treated by an electric furnace whose heat treatment temperature is to be measured. In step S10, the heat treatment temperature of the electric furnace is set to a predetermined set temperature Ts (100 ° C. in this embodiment), and the silicon substrate 10 is put into the electric furnace for a time t1 (30 seconds in this embodiment). As a result, the silicon substrate 10 is held at a temperature Tx (temperature to be measured) corresponding to the temperature Ts for approximately time t1. When the silicon substrate 10 is heat-treated, the number of crystal defects existing in the low resistance region 20 is greatly reduced. Therefore, the sheet resistance of the low resistance region 20 is greatly reduced. Hereinafter, the sheet resistance of the low resistance region 20 after execution of step S10 is referred to as post-heat treatment sheet resistance R1. The post-heat treatment sheet resistance R1 is a sheet resistance corresponding to the heat treatment temperature Tx, the heat treatment time t1, and the elapsed time t2.

  In step S12, the post-heat treatment sheet resistance R1 of the low resistance region 20 is measured at a predetermined measurement point on the surface (upper surface 12) of the low resistance region 20.

  In step S14, a calibration curve group showing the correlation among the heat treatment temperature Tx, the heat treatment time t1, the post-heat treatment sheet resistance R1, and the elapsed time t2 is prepared. The calibration curve group, the actual value ta2 of the elapsed time t2 measured in step S8, the actual value ta1 of the heat treatment time t1 of the heat treatment performed in step S10, and the actual value of the post-heat treatment sheet resistance R1 measured in step S12. From Ra1, the heat treatment temperature in the heat treatment step of Step S10 is specified.

  FIG. 5 illustrates some calibration curves A to D in the calibration curve group. Each of the calibration curves A to D is a calibration curve when the silicon substrate 10 having the sheet resistance R0 of 300Ω is heat-treated for 30 seconds (that is, a calibration curve when the heat treatment time t1 is 30 seconds). The calibration curve A is a calibration curve when the elapsed time t2 is 5 minutes. The calibration curve B is a calibration curve when the elapsed time t2 is 3 hours. The calibration curve C is a calibration curve when the elapsed time t2 is 48 hours. The calibration curve D is a calibration curve when the elapsed time is 96 hours. For example, the point H of the calibration curve D indicates that when the silicon substrate 10 having a sheet resistance R0 of 300Ω is heat-treated at 80 ° C. for 30 seconds 96 hours after the execution of step S6, the post-heat treatment sheet resistance R1 becomes 200Ω / sq. It shows that it becomes. Each calibration curve is created based on experiments conducted using an electric furnace having a known heat treatment temperature Tx. Note that the calibration curves A to D are examples, and the calibration curve group has a large number of calibration curves created every heat treatment time t1 and every elapsed time t2.

  In step S14, a calibration curve with matching conditions is selected from the calibration curve group. That is, a calibration curve in which the heat treatment time t1 coincides with the heat treatment time ta1 and the elapsed time t2 coincides with the elapsed time ta2 is selected. In this embodiment, the heat treatment time ta1 is 30 seconds and the elapsed time ta2 is 3 hours, so the calibration curve B is selected. Next, the heat treatment temperature Tx is specified from the selected calibration curve and the post-heat treatment sheet resistance Ra1. For example, when the post-heat treatment sheet resistance Ra1 is 205Ω / sq, the heat treatment temperature Tx is specified as 105 ° C. as shown in FIG. Accordingly, it can be understood that the actual heat treatment temperature Tx of the silicon substrate becomes 105 ° C. when the set temperature Ts is set to 100 ° C. in the electric furnace used in step S10.

As described above, in the heat treatment temperature measurement method of the first embodiment, the low resistance region 20 is formed on the surface portion of the silicon substrate 10 and crystal defects are formed in the low resistance region 20. The number of crystal defects in the low resistance region 20 decreases with time. Further, the rate of decrease in the number of crystal defects in the low resistance region 20 varies depending on the temperature at which the silicon substrate 10 is held. That is, the reduction rate of the sheet resistance in the low resistance region 20 varies depending on the temperature at which the silicon substrate 10 is held. Therefore, by measuring the post-heat treatment sheet resistance R1 of the silicon substrate 10, the heat treatment temperature of the silicon substrate can be specified.
Since the number of crystal defects formed in the low resistance region 20 decreases even at room temperature (that is, the sheet resistance of the low resistance region 20 decreases even at room temperature), according to this heat treatment temperature measurement method, The temperature can be measured.
In addition, the number of crystal defects formed in the low resistance region 20 rapidly decreases when the temperature of the silicon substrate 10 reaches 800 ° C. or more. Therefore, according to this heat treatment temperature measurement method, a temperature of less than 800 ° C. can be measured.

  Further, in the heat treatment temperature measuring method of the first embodiment, the low resistance region 20 is thinly formed on the surface portion of the silicon substrate 10. For this reason, the amount of decrease in sheet resistance due to a decrease in the number of crystal defects is very large. Therefore, more accurate temperature measurement is possible.

  Further, the silicon substrate 10 is composed only of a substance used for manufacturing a normal silicon semiconductor. Accordingly, there is no possibility that a substance that hinders the manufacture of the semiconductor device remains after the heat treatment.

  Further, the heat treatment temperature measuring method of the first embodiment can be implemented if there is an apparatus for implanting ions into the silicon substrate 10. In other words, it can be carried out using only an apparatus generally used for manufacturing a semiconductor device.

In the heat treatment temperature measurement method of the first embodiment, the n-type low resistance region 20 is formed on the surface portion of the p-type silicon substrate 10. When the low resistance region 20 is formed in this way, current is prevented from flowing between the low resistance region 20 (that is, the n-type region) and the p-type region of the silicon substrate 10. Therefore, the sheet resistance of the low resistance region 20 can be measured more accurately. That is, the heat treatment temperature Tx can be measured more accurately.
Note that the p-type low resistance region 20 may be formed on the surface portion of the n-type silicon substrate 10.

  In the above-described embodiment, the elapsed time t2 from the execution of step S6 to the execution of step S10 is measured. However, instead of the elapsed time t2, the sheet resistance (sheet resistance R2 before heat treatment) of the low resistance region 20 may be measured immediately before the heat treatment in step S10. Even when the pre-heat treatment sheet resistance R2 is used, the heat treatment temperature can be specified from the calibration curve as in the case of using the elapsed time t2. For example, when the heat treatment time t1 is 30 seconds, the post-heat treatment sheet resistance R1 (sheet resistance after holding the silicon substrate at room temperature for 30 seconds) of each calibration curve with each heat treatment time t1 being 30 seconds is confirmed. . The post-heat treatment sheet resistance R1 after holding the silicon substrate at room temperature for 30 seconds is not substantially different from the pre-heat treatment sheet resistance R2. Therefore, a calibration curve can be specified from the sheet resistance R2 before heat treatment. For example, when the sheet resistance R2 before heat treatment is 265Ω / sq, the calibration curve B in FIG. 5 can be specified. Therefore, the heat treatment temperature Tx is specified from the calibration curve B. Thus, the heat treatment temperature Tx can be accurately measured also by measuring the pre-heat treatment sheet resistance R2. That is, it can also be said that the calibration curve in FIG. 5 shows the correlation among the heat treatment temperature Tx, the heat treatment time t1, the post-heat treatment sheet resistance R1, and the pre-heat treatment sheet resistance R2.

  Further, as shown in FIG. 5, when the heat treatment time t1 is 30 seconds and the heat treatment temperature Tx is 150 ° C. or higher, the calibration curves A to D substantially coincide. That is, even if the silicon substrate 10 has a different elapsed time t2, the post-heat treatment sheet resistances R1 substantially match. The longer the heat treatment time t1, the smaller the difference in post-heat treatment sheet resistance R1 due to the difference in elapsed time t2. That is, when the heat treatment time t1 is 30 seconds or more and the heat treatment temperature Tx is 150 ° C. or more, the post-heat treatment sheet resistance R1 does not vary with the elapsed time t2. Therefore, when the expected heat treatment temperature Tx is 150 ° C. or higher (for example, when the set temperature Ts of the electric furnace is set to a temperature sufficiently higher than 150 ° C.), the heat treatment time t1 is 30 seconds or longer. When doing so, it is not necessary to measure the elapsed time t2. The heat treatment temperature Tx can be specified from the calibration curve group, the post-heat treatment sheet resistance R1, and the heat treatment time t1.

  In the first embodiment, the post-heat treatment sheet resistance R1 of the low resistance region 20 is measured at one measurement point in step S12. May be. When the sheet resistance R1 after heat treatment is measured at a number of measurement points, the heat treatment temperature Tx at each measurement point can be measured. That is, the distribution of the heat treatment temperature in the silicon substrate can be measured.

(Second embodiment)
Next, a method for measuring the heat treatment temperature (film formation treatment temperature) of the second embodiment will be described. In the heat treatment temperature measurement method of the second embodiment, the temperature at which the silicon substrate is held is measured when the insulating film is formed on the silicon substrate by the CVD apparatus.

  FIG. 7 shows a flowchart of the heat treatment temperature measuring method of the second embodiment. Also in the second embodiment, a p-type silicon substrate 30 is used as in the first embodiment.

  In step S20, a silicon oxide film 42 is formed on the upper surface 32 of the silicon substrate 30 as shown in FIG. The silicon oxide film 42 can be formed using a conventionally known technique. The silicon oxide film 42 is formed very thin.

In step S22, phosphorus ions are implanted into the silicon substrate 30 from the upper surface 32 side. At this time, phosphorus ions are implanted with energy that penetrates the silicon oxide film 42 and remains on the surface portion of the silicon substrate 30. Phosphorus ions are implanted at a concentration of about 1 × 10 ¹⁵ ions / cm ² .

  In step S24, the silicon substrate 30 is heat-treated together with the silicon oxide film. As a result, as shown in FIG. 9, the low resistance region 40 is formed on the surface portion of the silicon substrate 30 on the upper surface 32 side.

In step S26, phosphorus ions are implanted into the silicon substrate 30 from the upper surface 32 side. At this time, phosphorus ions are implanted with energy that penetrates the silicon oxide film 42 and remains on the surface portion of the silicon substrate 30. Phosphorus ions are implanted at a concentration of about 1 × 10 ¹³ ions / cm ² . As a result, the sheet resistance of the low resistance region 40 increases to the sheet resistance R0.

  In step S28, an insulating film is grown on the silicon oxide film 42 by a CVD apparatus whose temperature is to be measured. When the insulating film is grown by the CVD apparatus, the silicon substrate 30 is maintained at a substantially constant film formation temperature Tx. In step S30, the film forming process is performed only for time t1 (film forming process time t1). By performing step S28, an insulating film 44 is formed on the silicon oxide film 42 as shown in FIG.

  In step S30, the silicon oxide film 42 is selectively etched at room temperature with hydrofluoric acid or the like. As a result, the silicon oxide film 42 and the insulating film 44 are removed, and the upper surface 32 of the silicon substrate 30 is exposed.

  In step S32, the sheet resistance (sheet resistance R1 after film formation) is measured at a predetermined measurement point on the surface (upper surface 32) of the low resistance region 40 of the silicon substrate 30.

  In step S34, the film forming temperature Tx is specified from the calibration curve, the sheet resistance R1 after the film forming process, and the film forming process time t1. In the second embodiment, the film forming process time t1 is 30 seconds or more. It is also known in advance that the film formation temperature Tx during the film formation process is much higher than 150 ° C. Therefore, the film forming temperature Tx can be specified without measuring the elapsed time t2.

  As described above, according to the heat treatment temperature measurement method of the second embodiment, the film formation temperature Tx when the insulating film is grown by the CVD apparatus can be measured. According to this heat treatment temperature measurement method, since the silicon substrate 30 can be held in substantially the same state as when the semiconductor device is manufactured, the film formation temperature of the silicon substrate when actually manufacturing the semiconductor device is accurately measured. be able to. In the heat treatment temperature measurement method of the second embodiment described above, step S20 (silicon oxide film forming step) was performed before step S22 (impurity implantation step). However, step S22 may be performed at any timing as long as it is before step S26 (crystal defect formation step). For example, step S22 may be performed between step S24 and step S26.

  In the first and second embodiments described above, the temperature is measured using a silicon substrate, but the temperature may be measured using a substrate of another substance. For example, when measuring the temperature at which the gallium arsenide substrate is heat-treated, the temperature may be measured using a gallium arsenide substrate.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The flowchart which shows the heat processing temperature measuring method of 1st Example. 1 is a schematic sectional view of a silicon substrate 10. FIG. 1 is a schematic sectional view of a silicon substrate 10. FIG. The graph which shows the change with respect to the elapsed time t2 of the sheet resistance R of the low resistance area | region 20 after step S6 implementation. The graph which shows the example of the calibration curve of the silicon substrate. The graph which showed in more detail the range whose heat processing temperature Tx of the calibration curve B of FIG. 5 is 200 degrees C or less. The flowchart which shows the heat processing temperature measuring method of 2nd Example. 2 is a schematic cross-sectional view of a silicon substrate 30. FIG. 2 is a schematic cross-sectional view of a silicon substrate 30. FIG. 2 is a schematic cross-sectional view of a silicon substrate 30. FIG.

Explanation of symbols

10: silicon substrate 20: low resistance region 30: silicon substrate 40: low resistance region 42: silicon oxide film 44: insulating film

Claims (6)

A method for measuring a heat treatment temperature of a semiconductor substrate,
An impurity implantation step of implanting dopant impurities into the surface portion of the semiconductor substrate;
A low resistance region forming step of activating the impurities implanted in the impurity implantation step by heat treating the semiconductor substrate and forming a low resistance region on a surface portion of the semiconductor substrate;
Forming a crystal defect in the low resistance region by implanting ions into the low resistance region, and increasing the resistance of the low resistance region to a predetermined resistance; and
A heat treatment step of placing the semiconductor substrate for a predetermined heat treatment time t1 in a heat treatment apparatus held at a constant heat treatment temperature after the crystal defect formation step;
After the heat treatment step, a post-heat treatment resistance measurement step for measuring the post-heat treatment resistance R1 in the low resistance region;
A heat treatment temperature specifying step of specifying a heat treatment temperature in the heat treatment step from the correlation between the heat treatment temperature, the heat treatment time and the resistance after heat treatment, the heat treatment time t1, and the resistance after heat treatment R1;
A method for measuring a heat treatment temperature of a semiconductor substrate having It further has a post-defect formation elapsed time measuring step of measuring a post-defect formation elapsed time t2 from the implementation of the crystal defect formation step to the start of the heat treatment step,
In the heat treatment temperature specifying step, the heat treatment temperature, the heat treatment time, the post-heat treatment resistance and the elapsed time after defect formation, the heat treatment time t1, the post-heat treatment resistance R1, and the post-defect formation elapsed time t2 are used. 2. The heat treatment temperature measuring method according to claim 1, wherein the temperature is specified.   3. The heat treatment temperature measuring method according to claim 1, wherein in the impurity implantation step, a second conductivity type dopant impurity is implanted into the first conductivity type semiconductor substrate. In the post-heat treatment resistance measurement step, the post-heat treatment resistance R1 is measured at a plurality of measurement points in the low resistance region,
The heat treatment temperature measuring method according to any one of claims 1 to 3, wherein in the heat treatment temperature specifying step, the heat treatment temperature at each measurement point in the heat treatment step is specified from the post-heat treatment resistance R1 at each measurement point. A separation layer forming step to be performed before the crystal defect forming step, and a separation layer removing step to be performed between the heat treatment step and the post-heat treatment resistance measurement step,
In the separation layer forming step, a separation layer is formed on the surface of the semiconductor substrate,
In the crystal defect forming step, the ions are implanted into the surface portion of the semiconductor substrate through the separation layer,
In the heat treatment step, an insulating layer is formed on the separation layer,
5. The heat treatment temperature measuring method according to claim 1, wherein in the separation layer removing step, the insulating layer and the separation layer are removed in a state where the semiconductor substrate is kept at room temperature. Immediately before carrying out the heat treatment step, it further comprises a pre-heat treatment resistance measurement step for measuring the pre-heat treatment resistance R2 in the low resistance region,
In the heat treatment temperature specifying step, the heat treatment temperature in the heat treatment step is specified from the correlation between the heat treatment temperature, the heat treatment time, the post-heat treatment resistance and the pre-heat treatment resistance, the heat treatment time t1, the post-heat treatment resistance R1, and the pre-heat treatment resistance R2. The heat treatment temperature measuring method according to claim 1.

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