JP2008004603A - Semiconductor manufacturing apparatus, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure the thickness of a film stacked in a reaction furnace (chamber) even if its optical property is changed due to the aging of a base material. <P>SOLUTION: The semiconductor manufacturing apparatus is provided with a reaction furnace 2 wherein semiconductor wafers are housed for film formation, and a film formation gas for forming a film on the semiconductor wafer and a cleaning gas for cleaning a film stacked on the inner wall of the reaction furnace are introduced thereto. It is also provided with a light emitter 1 to emit a light; a light receiver 3 to receive the light which is emitted from the light emitting section, and passes through the reaction furnace and to measure transmissivities of a plurality of wavelengths of the received light; and a calculation section 5 to decide to execute at least one of cleaning of the inside of the reaction furnace using the transmissivity in the specified range of wavelength and repalcement of the reaction furnace, or to determine completion timing of cleaning within the reaction furnace. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor manufacturing apparatus and a semiconductor device manufacturing method.

  An apparatus for depositing a film in a reaction furnace using a quartz reaction furnace (chamber) such as a chemical vapor deposition (hereinafter, referred to as CVD) apparatus, a silicon oxide film or the like in the reaction furnace. A CVD deposited film is deposited. When such a CVD deposited film becomes too thick, there is a problem that film peeling occurs and dust contamination occurs, and when the deposited film thickness in the reaction furnace is non-uniform, a film is formed on a semiconductor wafer. There is a problem that the CVD film to be formed is not uniformly formed.

  Therefore, conventionally, before such a problem becomes prominent, cleaning is performed to remove the deposited film by an etching process using a cleaning gas containing a halogen such as chlorine trifluoride (ClF 3). Normally, cleaning is performed on a wafer that is difficult to process in a normal lot, for example, due to dust contamination due to excessive film thickness, dust contamination due to excessive film thickness, or uneven film thickness on a member. This is implemented when a situation such as deterioration of film thickness uniformity occurs. Further, the time when these defects occur is empirically known from the accumulated film thickness, and the cleaning execution time is determined only for such defects.

  Also, the cleaning execution time is a time that is determined to be sufficient empirically from the accumulated film type and accumulated film thickness, and it takes a lot of time because the end point time is unknown. In addition, the quartz in the chamber was also etched by cleaning. This leads to devitrification of the quartz material, increased surface roughness, and decreased thickness. The devitrification of the quartz material causes a reduction in radiant heat generated by the heater. Surface roughness of the quartz material increases the gas consumption and deteriorates the gas concentration distribution in the chamber. A decrease in the thickness of the quartz material causes a leak due to pinholes. Such problems were caused by not knowing the proper cleaning time.

  In order to solve this problem, cleaning is performed by detecting the light intensity of one wavelength emitted from the tip of the quartz tube installed inside the quartz inner tube with an infrared radiation thermometer and monitoring the change in light intensity. Has been proposed (see Patent Document 1).

However, in the conventional cleaning end point detection method as described above, if the optical properties change due to the aging of the base material that transmits light, and the light transmittance changes, an error occurs in the detected light intensity. However, the film thickness of the film deposited in the reaction furnace (chamber) cannot be measured with high accuracy, and cleaning cannot be completed at an appropriate time.
Japanese Patent Laid-Open No. 11-200053

  The present invention has been made to solve the above-described problems. Even when the optical properties change due to the aging of the base material, the cleaning time of the film deposited in the reaction furnace (chamber) and the cleaning end time are as follows. It is another object of the present invention to provide a semiconductor manufacturing apparatus capable of appropriately determining a chamber replacement time.

  A semiconductor manufacturing apparatus according to one aspect of the present invention includes a reaction furnace that accommodates a semiconductor wafer and performs film formation, and a film deposition gas for forming a film on the semiconductor wafer and a film deposited on an inner wall of the reaction furnace are provided. A semiconductor manufacturing apparatus into which a cleaning gas for cleaning is introduced, wherein a light emitting unit that emits light, and the light emitted from the light emitting unit and transmitted through the reaction furnace are received, and the received light at a plurality of wavelengths A light receiving unit for measuring transmittance, determination of whether or not to clean the inside of the reaction furnace using the transmittance in a predetermined wavelength range, determination of completion time of cleaning in the reaction furnace, and the reaction furnace And a calculation unit that performs at least one of the determinations as to whether or not to exchange them.

  A method of manufacturing a semiconductor device according to an aspect of the present invention includes a light emitting unit, a light receiving unit, a calculation unit, and a reaction furnace that houses a semiconductor wafer to form a film, and a film forming gas for forming a film on the semiconductor wafer And a semiconductor device manufacturing method using a semiconductor manufacturing apparatus into which a cleaning gas for cleaning a film deposited on the inner wall of the reaction furnace is introduced, wherein the light emitting unit emits light, and the light receiving unit emits the light emitting unit. Is emitted, the light transmitted through the reactor is received, the transmittance of the received light at a plurality of wavelengths is measured, and the calculation unit uses the transmittance in a predetermined wavelength range in the reactor. This includes at least one of determination of whether to perform cleaning, determination of the end time of cleaning in the reaction furnace, and determination of whether to replace the reaction furnace.

  According to the present invention, it is possible to appropriately determine the cleaning time of the film deposited in the chamber, the cleaning end time, and the chamber replacement time.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of a semiconductor manufacturing apparatus according to an embodiment of the present invention.

  The semiconductor manufacturing apparatus of the present embodiment is a low pressure vapor deposition (hereinafter referred to as LPCVD) apparatus for forming a silicon nitride film (hereinafter referred to as SiN film). The light emitting unit 1 is installed outside the quartz chamber 2 and emits light that passes through the quartz material. In this embodiment, a halogen lamp is used. You may make it the structure which uses the infrared rays emitted from the heater for reactor heating. The light emitting unit 1 emits light after film formation on the semiconductor wafer, during cleaning in the quartz chamber, and after completion of cleaning in the quartz chamber.

  The light receiving unit 3 receives the light emitted from the light emitting unit 1 and transmitted through the quartz material, and measures the transmittance for each of a plurality of wavelengths as spectrum data of the received light. A semiconductor detector, a scintillation detector, a proportional counter detector, or the like can be used as the sensor of the light receiving unit 3. The spectrum data measured by the light receiving unit 3 is sent to and stored in the storage unit 4. The storage unit 4 also stores reference spectral data such as spectral data immediately after replacement of the quartz material, spectral data immediately after the previous cleaning, and spectral data after the previous film formation.

  The calculation unit 5 can use the stored spectral data to determine whether or not the quartz chamber 2 needs to be cleaned, determine whether or not to clean the quartz chamber 2, and use the quartz material in the quartz chamber 2. Whether or not (use limit has come) is determined. The result calculated by the calculation unit 5 can be stored in the storage unit 4. The determination result can be displayed on the display unit 6 and can be confirmed by the user.

When forming a SiN film on the wafer, a film forming gas (SiH ₂ Cl ₂ and NH ₃ ) is introduced into the quartz chamber 2 through the film forming gas introduction pipe 7. Further, when cleaning the quartz chamber 2, a cleaning gas (chlorine trifluoride ClF ₃ ) is introduced into the quartz chamber 2 through the cleaning gas introduction pipe 8. The film forming gas and the cleaning gas are exhausted from the exhaust pipe 9 to the outside of the quartz chamber 2.

  With reference to the flowchart shown in FIG. 2, the flow of the cleaning process of the semiconductor manufacturing apparatus and the operation of each part will be described. The spectral data of the transmitted light measured by the light receiving unit 3 uses the number of cleanings i performed after the quartz chamber 2 is attached to the LPCVD apparatus, the number of film depositions j performed since the previous cleaning, and the wavelength of light x. And store it in the form of y (i, j, x). The wavelength of the light to be measured is from 0.1 to 1.0 μm in increments of 0.001 μm.

  (Step 1) An unused quartz chamber is attached to the apparatus.

  (Step 2) Obtain spectral data y (0,0, x) of transmitted light immediately after the unused quartz chamber is attached.

  (Step 3) A SiN film is formed on a semiconductor wafer with an LPCVD apparatus. A 20 nm SiN film is formed at a time.

  (Step 4) Obtain spectral data after film formation on a semiconductor wafer. Spectral data after film formation on the semiconductor wafer j times is y (0, j, x). Moreover, after performing cleaning i times, the spectrum data after performing film formation j times is y (i, j, x).

  (Step 5) The function z defined by z (i, j, x) = y (i, j, x) + y (0,0, x) −y (i, 0, x) is calculated by the calculation unit. To do. The function z is obtained by adding the spectrum data immediately after the unused quartz material is attached to the spectrum data obtained in step 4 and subtracting the spectrum data after the previous cleaning in the chamber. As a result, the influence of devitrification of the quartz material accumulated until the cleaning is performed i times is eliminated, and z becomes data as if the film was formed j times after the unused quartz material was attached. Therefore, it is possible to reduce an error in transmittance caused by a change in the quartz material accompanying a change with time.

  Then, it is examined whether z ′, which is a single derivative of z, may become 0 within a range of 0.25 ≦ x ≦ 0.70 μm. That is, it is examined whether or not the value of z changes from increasing to decreasing or decreasing to increasing within the range of 0.25 ≦ x ≦ 0.70 μm.

  In the case where there is a wavelength where z ′ = 0, the wavelength having a wavelength of 0.70 μm or less and the largest convex distribution (the curve is convex upward) where z ′ = 0 is m1. In the present embodiment, when m1 is 0.65 μm or more, it is determined that the SiN film deposited on the inner wall of the quartz chamber 2 has reached the film thickness to be cleaned, and the process proceeds to step 6 to perform cleaning. When m1 is less than 0.65 μm, the process returns to step 3 and the film formation is repeated until m1 becomes 0.65 μm or more.

  FIG. 3 shows the relationship between the wavelength and transmittance when the deposited film thickness on the inner wall of the chamber is 0, 40, 80, and 150 nm. It can be seen that the greater the deposited film thickness, the greater the frequency of change in transmittance. Also, the difference in transmittance increase / decrease depending on the film thickness becomes clear when the wavelength is 200 nm (= 0.2 μm) or more. This is why the wavelength range for examining the increase / decrease change of the function z is set to 0.25 ≦ x ≦ 0.70 μm. This wavelength range is also suitable for approximating (fitting) the function z, which is discrete data obtained at wavelengths of 0.001 μm, with a continuous function (exponential function).

  Examples of curves representing the function z are shown in FIGS. FIG. 4 shows an example when the deposited film thickness is thick, and FIG. 5 shows an example when the deposited film thickness is thin. When the deposited film thickness is thin, the frequency of increase / decrease in the function z is small and m1 is small. It can be seen that the value of m1 increases as the deposited film thickness increases.

  (Step 6) A cleaning gas is introduced into the quartz chamber 2 to perform cleaning. During the cleaning, spectrum data y2 (i, t, x) is measured every predetermined time. t is the time (seconds) elapsed from the start of cleaning. In this embodiment, the spectrum data is measured in increments of 1 second. Then, at each time, it is checked whether there is a wavelength at which the first derivative y2 ′ of y2 becomes zero. When there is a wavelength where y2 ′ = 0, the largest wavelength of the convex distribution where y2 ′ = 0 is n1. An example of a curve obtained by plotting the spectrum data y2 (i, t, x) is shown in FIG. When n1 is 0.25 μm or less and y2 (i, t, 0.25) is y2 (i−1, t, 0.25) × 0.95 or more, it is determined that the deposited SiN film is gone. Finish cleaning. When the cleaning is completed, the process proceeds to Step 7.

  Here, the value obtained by multiplying the transmittance at the end of the previous cleaning by 0.95 as a reference is based on the transmittance smaller than that at the end of the previous cleaning in consideration of the devitrification caused by the film formation. Because. In the present embodiment, the transmittance is 5% smaller than that at the end of the previous cleaning.

  (Step 7) Spectrum data y (i + 1,0, x) after cleaning is measured and stored in the storage unit 4. After saving, go to step 8.

  (Step 8) Ratio r (i + 1, x) = y (i + 1,0,) of spectrum data y (i, 0, x) after the previous cleaning and spectrum data y (i + 1,0, x) after the current cleaning x) / y (i, 0, x) is calculated by the calculation unit 5. After calculating the ratio r, go to step 9.

  (Step 9) The calculation unit 5 checks whether r (i + 1, x) may exceed 0.05 (= 5%) within the range of 0.25 μm ≦ x ≦ 0.70 μm. If yes, go to Step 12. If not, go to Step 10.

  (Step 10) The ratio r0 (i + 1, x) = y (i + 1, x) between the spectral data y (0,0, x) immediately after the unused quartz chamber is mounted and the spectral data y (i + 1,0, x) after this cleaning is performed. The calculation unit 5 calculates 0, x) / y (0,0, x). After calculating the ratio r0, the process proceeds to step 11.

  (Step 11) The calculation unit 5 checks whether r0 (i + 1, x) exceeds 0.6 (= 60%) within the range of 0.25 μm ≦ x ≦ 0.70 μm. If yes, go to Step 12. If not, the process returns to step 3 to form a SiN film on the semiconductor wafer.

  (Step 12) The use limit (life) of the quartz chamber 2 has been reached, it is determined that it is time to replace it, and the content is displayed on the display unit 6. The use limit of the quartz chamber was also determined in step 11 because the change in the quartz base material, which is less devitrified in one cleaning and cannot be determined in step 9, is compared with the spectrum data immediately after the unused quartz chamber is attached. This is because the determination is made by

  The light transmittance of the quartz chamber 2 is changed not only by the deposited film thickness but also by the change (devitrification) of the base material with time. In the present embodiment, the change of the base material is taken into consideration. In step 6, the largest wavelength n1 of the convex distribution where y2 ′ = 0 is 0.25 μm or less, and y2 (i, t, 0.25) is When the spectrum data y2 (i-1, t, 0.25) after the previous cleaning is 95% or more, the cleaning is finished. In step 8, the ratio r (i + 1, x) = y (i + 1,0) of the spectral data y (i, 0, x) after the previous cleaning and the spectral data y (i + 1,0, x) after the current cleaning is performed. , x) / y (i, 0, x) is obtained and used for predicting the lifetime of the quartz chamber 2. Between the spectral data y (i, 0, x) after the previous cleaning and the spectral data y (i + 1,0, x) after the current cleaning are not greatly affected by changes in the base material due to changes over time. The life prediction of the quartz chamber 2 using the ratio r (i + 1, x) can reduce the error.

  As described above, the semiconductor manufacturing apparatus according to the embodiment of the present invention can appropriately determine the cleaning time of the film deposited in the quartz chamber, the cleaning end time, and the replacement time of the quartz chamber.

  The above-described embodiment is an example and should not be considered restrictive. For example, instead of m1 in step 5, the wavelength m2 having the largest concave distribution (convex downward) with z ′ = 0 among the wavelengths below m1 as shown in FIG. 7 may be used as a reference. . When m2 is used as a reference, whether or not the inside of the chamber is cleaned is determined, for example, by whether or not m2 is 0.64 μm or more.

  Further, as shown in FIG. 8, a straight line L1 connecting a point of z (i, j, 0.7) having a wavelength of 0.7 μm and a point of z (i, j, m1) having a wavelength of m1. May be used based on the slope or intercept. As the deposited film thickness increases, the slope of L1 becomes steep. For example, it is determined that the cleaning is performed when the slope of L1 becomes −10 (unit: 1 / μm) or less.

  Further, as shown in FIG. 9, a straight line L2 connecting a point of z (i, j, 0.7) having a wavelength of 0.7 μm and a point of z (i, j, m2) having a wavelength of m2. You may use on the basis of inclination and intercept. Alternatively, the slope or intercept of the straight line L3 connecting the point z (i, j, m1) and the point z (i, j, m2) may be used as a reference.

  In the above-described embodiment, the spectrum data is measured every time when the film formation is completed. However, the measurement may be performed every time the time when the film formation gas is introduced into the quartz chamber 2 reaches a predetermined value. In this case, spectrum data may be measured during film formation according to a predetermined value.

  Further, as shown in FIG. 10, in step 6, a point y2 (i, t, 0.25) having a wavelength of 0.25 μm and a point y2 (i, t, n1) having a wavelength n1 are obtained. The slope or intercept of the connected straight line L4 may be used as a criterion for determining the end of cleaning. Alternatively, the slope or intercept of the straight line L5 connecting the point y2 (i, t, n1) and the point y2 (i, t, 0.7) having a wavelength of 0.7 μm may be used as a reference.

  In step 9, the ratio r (i + 1, x) may be approximated (fitted) to a continuous function (exponential function), and the tangent slope or intercept at a predetermined wavelength may be used as a reference. Further, not the ratio r (i + 1, x) but the slope of the tangent at a predetermined wavelength when y (i + 1,0, x) in the range of 0.25 μm ≦ x ≦ 0.70 μm is approximated by an exponential function, A section may be used as a reference.

  In step 11, the ratio r0 (i + 1, x) may be approximated (fitted) to a continuous function (exponential function), and the tangent slope or intercept at a predetermined wavelength may be used as a reference.

  Further, instead of the spectrum data y (i, j, x), the quartz transmittance correction spectrum yc defined by yc (i, j, x) = y (i, j, x) / r0 (i, x) It may be determined whether or not the chamber is cleaned using (i, j, x).

  Infrared rays emitted from the heater 12 for heating the chamber can be used as the transmitted light in the above embodiment. In addition, light from various lasers or the like can be used as transmitted light, and the spectrum distribution varies depending on the light used, so the wavelength range used for measurement varies depending on the type of transmitted light.

  Quartz materials are often used for the quartz tube 10, the film forming gas introduction pipe 7, the cleaning gas introduction pipe 8, the wafer boat 11 and the like as well as the quartz chamber 2, and the light emitting part 1 ′ and the corresponding light receiving part 3 ′ are used. By using the method of the above embodiment, it is possible to determine the cleaning time of the film deposited thereon.

  The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows schematic structure of the semiconductor manufacturing apparatus by one Embodiment of this invention. It is a figure which shows the flowchart of a process of the semiconductor manufacturing apparatus by the same embodiment. It is a graph which shows an example of the spectrum data of the transmitted light for every deposited film thickness. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light. It is a graph which shows an example of the spectrum data of transmitted light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission part 2 Quartz chamber 3 Light reception part 4 Memory | storage part 5 Calculation part 6 Display part 7 Film-forming gas introduction pipe 8 Cleaning gas introduction pipe 9 Exhaust pipe 10 Quartz tube 11 Wafer boat 12 Heater 13 Apparatus housing

Claims (5)

A semiconductor having a reaction furnace for forming a film by containing a semiconductor wafer, into which a film forming gas for forming a film on the semiconductor wafer and a cleaning gas for cleaning a film deposited on the inner wall of the reaction furnace are introduced Manufacturing equipment,
A light emitting unit that emits light;
A light-receiving unit that emits the light-emitting unit, receives light transmitted through the reactor, and measures transmittance at a plurality of wavelengths of the received light;
Determining whether or not to clean the inside of the reactor using the transmittance in a predetermined wavelength range, determining whether or not to clean the reactor, and determining whether or not to replace the reactor A calculation unit that performs at least one of
A semiconductor manufacturing apparatus comprising:   The calculation unit performs cleaning in the reactor i (i is an integer of 0 or more) times after mounting the reactor in the predetermined wavelength range, and j (j is an integer of 1 or more) ) After adding the reactor, the transmittance before the deposition of the semiconductor wafer after adding the reactor is added, and after the reactor is installed, the semiconductor wafer is cleaned i times after the reactor is installed. The semiconductor manufacturing apparatus according to claim 1, wherein it is determined whether or not the (i + 1) th cleaning in the reaction furnace is performed based on a result obtained by subtracting the transmittance before the film formation.   The calculation unit determines the end time of cleaning in the reactor by comparing the transmittance in a predetermined wavelength range during cleaning in the reactor with the transmittance at the end of the previous cleaning in the reactor. The semiconductor manufacturing apparatus according to claim 1 or 2.   After calculating the inside of the reaction furnace k times (k is an integer of 1 or more), the calculation unit performs the transmittance before film formation of the semiconductor wafer and the cleaning inside the reaction furnace k-1 times. The ratio of the transmittance before deposition of the semiconductor wafer and the transmittance before deposition of the semiconductor wafer after the inside of the reactor is cleaned k times and the deposition of the semiconductor wafer after mounting the reactor 4. The semiconductor manufacturing apparatus according to claim 1, wherein at least one of the previous transmittance ratios is calculated, and whether or not to replace the reactor is determined based on the result. 5. . A light emitting unit, a light receiving unit, a calculation unit, and a reaction furnace that contains a semiconductor wafer to form a film are formed, and a film forming gas for forming a film on the semiconductor wafer and a film deposited on the inner wall of the reaction furnace are cleaned. A method of manufacturing a semiconductor device using a semiconductor manufacturing apparatus into which a cleaning gas is introduced,
Emitting light by the light emitting unit,
The light emitting unit emits light from the light receiving unit, receives light transmitted through the reactor, and measures the transmittance of the received light at a plurality of wavelengths,
Whether the calculation unit determines whether to clean the inside of the reactor using the transmittance in a predetermined wavelength range, whether to determine the end time of cleaning in the reactor, and whether to replace the reactor A method of manufacturing a semiconductor device, comprising: performing at least one of determinations of whether or not.

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