JP2006222373A - Dry etching system and dry etching method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching system which can accurately detect the end point of dry etching. <P>SOLUTION: In the dry etching system, a substrate to be treated in a reaction chamber 100 is treated by dry etching using plasma made of reactive gas. The reaction gas is generated by supplying radiofrequency power into the reaction chamber 100 where the reaction gas has been introduced. The dry etching system comprises a photoluminescence detector 106 which detects the intensity of photoluminescence from the treated substrate according to the elapsed time since the start of dry etching. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser manufacturing, in particular, a dry etching apparatus used for forming a ridge pattern, and a dry etching method using the apparatus.

  For a red semiconductor laser used as a light source in an optical disc system such as a recording / reproducing DVD or a high-speed CD-R / RW, it is strongly required to realize a semiconductor laser capable of high output operation.

  According to the market demand in 2003, a red semiconductor laser capable of outputting power up to 160 mW was required. In 2004, a red semiconductor laser capable of outputting power of 240 mW appeared on the market. After 2006, it is considered that a red semiconductor laser capable of outputting power of 400 mW or more is required from the market.

  In order to realize such a high output of the red semiconductor laser, it is necessary to improve the kink level. To improve the kink level, the bias of the carrier distribution and the light distribution in the resonator of the semiconductor laser is reduced. It is important to.

  For this reason, in recent years, there has been a demand for the realization of a semiconductor laser having a ridge pattern having a shape excellent in symmetry and perpendicularity, thereby reducing the bias of carrier distribution and light distribution in the resonator of the semiconductor laser. Can be reduced.

  In order to meet such a demand, a dry etching method capable of anisotropic etching is being adopted as a ridge pattern forming method instead of the wet etching method.

  Hereinafter, a conventional dry etching apparatus used in a method for forming a ridge pattern using a dry etching method will be described with reference to FIG.

  FIG. 7 is a cross-sectional view showing a configuration of a conventional dry etching apparatus.

  As shown in FIG. 7, a lower electrode 401 is provided at the bottom of the reaction chamber 400, and a substrate to be processed (not shown) is placed on the lower electrode 401. On the other hand, an upper electrode 402 is provided on the ceiling of the reaction chamber 400 so as to face the lower electrode 401 across a space for generating plasma.

  The reaction chamber 400 is provided with a high frequency power source 403, and power of, for example, 13.56 MHz is applied to the lower electrode 401 using the high frequency power source 403. The reaction chamber 400 is also provided with a gas inlet 404 for introducing a reactive gas into the reaction chamber 400 and a gas exhaust port 405 for discharging the reactive gas from the reaction chamber 400. .

  Further, the reaction chamber 400 is provided with a plasma light emission detection device 406. The plasma light emission detection device 406 corresponds to the intensity of plasma light emission from a predetermined plasma corresponding to the elapsed time from the start of dry etching. Is detected.

  Hereinafter, a semiconductor laser manufacturing method using a conventional dry etching apparatus, specifically, a ridge pattern forming method will be described with reference to FIGS. 8 (a) to (d), FIG. 9, and FIG. 7 described above. While explaining.

  8 (a) to 8 (d) are cross-sectional views of main steps showing a semiconductor laser manufacturing method using a conventional dry etching apparatus.

  FIG. 9 is a diagram showing the intensity of plasma emission from a predetermined plasma corresponding to the elapsed time from the start of dry etching.

  First, as shown in FIG. 8A, an active layer formed by laminating a clad layer 501 made of n-type AlGaInP, a GaInP layer, and an AlGaInP layer on a substrate 500 made of n-type GaAs using MOCVD. 502, a first cladding layer 503 made of p-type AlGaInP, an etching stop layer (hereinafter referred to as an ES layer) 504 made of GaInP, and a second ladder layer 505 made of p-type AlGaInP are stacked in this order from the bottom.

  Subsequently, a resist 506 patterned into a desired shape is formed on the second cladding layer 505 by using lithography and etching techniques.

  Here, the active layer 502 is made of a material that induces and emits PL light by absorbing light having a specific wavelength incident on the layer.

  Next, a semiconductor substrate 500 on which a plurality of semiconductor layers (501 to 505) and the like are formed is transferred into a reaction chamber 400 (see FIG. 7 described above) in a conventional dry etching apparatus, and on the lower electrode 401, A semiconductor substrate 500 on which a plurality of semiconductor layers (501 to 505) and the like are formed is provided.

  Subsequently, a reactive gas is supplied into the reaction chamber 400 through the gas inlet 404, and high frequency power is supplied into the reaction chamber 400 using the high frequency power source 403. Accordingly, in the reaction chamber 400, plasma made of a reactive gas is generated and dry etching using the plasma is performed on the second cladding layer 505.

  In this way, dry etching of the portion of the second cladding layer 505 where the resist 506 is not present is started.

  With the start of dry etching, plasma emission from a predetermined plasma, specifically, plasma derived from the second cladding layer 505 starts to be observed.

  For this reason, as shown in FIG. 9, the intensity of plasma emission from the plasma derived from the second cladding layer 505 gradually increases with the start of dry etching.

  Next, as shown in FIG. 8B, as dry etching in the second cladding layer 505 proceeds, a portion of the second cladding layer 505 where the resist 506 is not present starts to be selectively removed.

  As described above, when the second cladding layer 505 is dry-etched, plasma emission from the plasma derived from the second cladding layer 505 is stably observed, as shown in FIG. In addition, during the etching time t1 to the etching time t3, the plasma emission from the plasma derived from the second cladding layer 505 exhibits a substantially constant intensity.

  Next, as shown in FIG. 8C, with further progress of dry etching, part of the second cladding layer 505 where the resist 506 is not present is completely removed, and ES An exposed portion 504a in which a part of the layer 504 is exposed is formed.

  For this reason, as shown in FIG. 9, the intensity of the plasma emission from the plasma derived from the second cladding layer 505 gradually decreases as the dry etching further progresses.

  Further, as the dry etching further progresses, as shown in FIG. 9, the intensity of plasma emission from the plasma derived from the second cladding layer 505 does not decrease at the etching time t4, and the intensity is almost constant. Indicates.

  As described above, in the conventional dry etching apparatus, as shown in FIG. 9, when the intensity of the plasma emission from the second cladding layer 505 is reduced, the etching time t4 is set to the second time. The semiconductor substrate 500 is unloaded from the reaction chamber 400 as an end point of dry etching in the cladding layer 505.

  Here, when the second cladding layer 505 is further subjected to dry etching without carrying out the semiconductor substrate 500 from the reaction chamber 400, as shown in FIG. 8D, the second cladding layer 505 is used. The portion where the resist 506 is not present in is completely removed, and the ridge pattern 505a having a desired shape can be formed.

  However, as shown in FIG. 8D, a dug 507 is formed in the ES layer 504 and the first cladding layer 503.

  As described above, in the method of manufacturing a semiconductor laser using a conventional dry etching apparatus, the plasma emission detection apparatus 406 provided in the apparatus is used to correspond to the elapsed time from the start of dry etching, The intensity of plasma emission from the plasma derived from the second cladding layer 505 is detected. Thereby, the end point of dry etching in the second cladding layer 505 is detected.

  However, the semiconductor laser manufacturing method using the conventional dry etching apparatus has the following problems.

  When dry etching is continuously performed on the second cladding layer 505 in order to form the ridge pattern 505a having a desired shape, as shown in FIG. 8D, the ES layer 504 and the first cladding layer are formed. A dug portion 507 is formed at 503. Thereby, the numerical value of the refractive index which the 1st cladding layer 503 has becomes larger than the numerical value of the refractive index set beforehand.

  For this reason, in the manufacturing method of the semiconductor laser using the conventional dry etching apparatus, not only the yield of the semiconductor laser is lowered but also a semiconductor laser having desired laser characteristics cannot be realized.

  Further, during dry etching, the pressure in the reaction chamber 400 fluctuates due to the product of the dry etching reaction adhering in the reaction chamber 400, thereby causing fluctuations in plasma emission.

  For this reason, the semiconductor laser manufacturing method using the conventional dry etching apparatus cannot detect the end point of the dry etching in the second cladding layer 505 with good reproducibility.

  In particular, when the etching time t3 is detected instead of the etching time t4 as the end point of the dry etching, the time when the intensity of the plasma emission changes due to the pressure fluctuation in the reaction chamber 400, that is, the time when the fluctuation of the plasma emission occurs. Since there is a possibility that the etching end point is detected by mistake, a ridge pattern having a desired shape cannot be formed.

  In order to solve these problems, a method for forming a ridge pattern using a dry etching method and a wet etching method in combination has been proposed as a method of manufacturing a red semiconductor laser (for example, Non-Patent Document 1 and Patent Document 1).

  10A to 10C and FIG. 7 described above with respect to a method for manufacturing a semiconductor laser, specifically, a method for forming a ridge pattern, using a dry etching method and a wet etching method in combination. Will be described with reference to FIG.

  10 (a) to 10 (c) are cross-sectional views of essential steps showing a method of manufacturing a semiconductor laser using a dry etching method and a wet etching method in combination.

  10A to 10C, the same components as those of the semiconductor laser described above are denoted by the same reference numerals. Therefore, in the following description, the same description as the semiconductor laser described above will not be repeated.

  First, as shown in FIG. 10 (a), a plurality of semiconductor layers (501 to 505) are formed on the semiconductor substrate 500 using the MOCVD method in the same manner as the process shown in FIG. 8 (a). At the same time, a resist 506 patterned into a desired shape is formed on the second cladding layer 505.

  Here, the active layer 502 and the ES layer 504 are configured using a material that induces and emits PL light by absorbing light having a specific wavelength incident on the layers.

  Next, as shown in FIG. 10B, the second cladding layer 505 is dry-etched by using a conventional dry etching apparatus (see FIG. 7 described above), and the second cladding layer 505 is then etched. The second cladding layer 505b is formed by selectively removing the portion of the second cladding layer 505 where the resist 506 is not present from the surface of the portion where the resist 506 is present to a predetermined depth d. .

  Next, as shown in FIG. 10C, wet etching is performed on the second cladding layer 505b using a chemical solution made of tartaric acid and hydrogen peroxide.

  As a result, the remaining portion of the second cladding layer 505 b after dry etching is completely removed to expose a part of the ES layer 504, and a ridge pattern 505 c is formed on the ES layer 504.

  As described above, in the semiconductor laser manufacturing method using both the dry etching method and the wet etching method, the remaining portion of the second cladding layer 505b is completely removed as shown in FIG. This state is the end point of wet etching.

  For example, as a method for detecting the end point of wet etching, there is a method using PL light emission from the ES layer 504 (see, for example, Patent Document 2, Patent Document 3, and Utility Model Document 1).

  In this method, during wet etching, the ES layer 504 is irradiated with light having a specific wavelength using an external light source provided in a wet etching apparatus (not shown). Since the light emitted into the ES layer 504 is absorbed into the ES layer 504, PL light emission is stimulated and emitted from the ES layer 504, so that PL light emission from the ES layer 504 is observed.

  Thus, the end point of wet etching is detected by using PL light emission from the ES layer 504.

  As described above, in the semiconductor laser manufacturing method using both the dry etching method and the wet etching method, an appropriate chemical solution can be selected during the wet etching. The selection ratio of the second cladding layer 505b can be 100 or more.

  For this reason, wet etching is not performed on the first cladding layer 503, and therefore, as described above, the dug 507 (see FIG. 8D described above) is formed in the ES layer 504 and the first cladding layer 503. 507) is not formed.

  Further, when PL emission from the ES layer 504 is used as a method for detecting the end point of wet etching, the PL emission from the ES layer 504 is affected by pressure fluctuation in the reaction chamber 400 as compared with plasma emission. It is hard to receive.

For this reason, the PL emission from the ES layer 504 does not fluctuate greatly during wet etching, so that the end point of the wet etching in the second cladding layer 505 can be detected with good reproducibility.
Hiroyama et al., "High-power 200mW 660nm AlGaInP Laser Diodes with Low Operating Current", Japanese Journal of Applied Physics, vol.43, No.4B, pp.1951-1955 (2004). JP 2003-69154 A JP-A-6-13446 JP-A-10-233384

Utility model document 1

  Published Utility Model Gazette 3-110836

  However, the semiconductor laser manufacturing method using both the dry etching method and the wet etching method has the following problems.

  Generally, wet etching is isotropic etching. As shown in FIG. 10C, a ridge pattern 505c formed by using a wet etching method has a side-etched shape.

  In the red semiconductor laser, an AlGaInP-based material is used as the material of the second cladding layer 505, and the (111) surface, which is a stable surface, is exposed during wet etching in the second cladding layer 505b. A ridge pattern 505c is formed. On the other hand, a 10 ° off substrate with respect to the (100) plane is used as the semiconductor substrate 500 made of GaAs.

  For this reason, as shown in FIG. 10C, the ridge pattern 505c formed using the wet etching method has an asymmetric shape.

  As described above, the ridge pattern forming method using both the dry etching method and the wet etching method cannot realize a semiconductor laser having a ridge pattern having a shape with excellent perpendicularity and symmetry. .

  As described above, as long as the wet etching method is used as a semiconductor laser manufacturing method, specifically, a ridge pattern forming method, a semiconductor laser having a ridge pattern having a shape with excellent verticality and symmetry is realized. Therefore, it is difficult to provide a semiconductor laser capable of high power operation.

  In view of the above, an object of the present invention is to provide a dry etching apparatus capable of accurately and reproducibly detecting an end point in dry etching and a dry etching method using the apparatus without using a wet etching method. To provide a semiconductor laser having a ridge pattern having a shape excellent in perpendicularity and symmetry by using only a dry etching method.

  In order to solve the above-described problems, a dry etching apparatus according to the present invention performs dry etching using plasma made of reactive gas, which is generated by supplying high-frequency power into a reaction chamber into which reactive gas is introduced, A dry etching apparatus for processing a substrate to be processed installed in a reaction chamber, which detects a photoluminescence light intensity from a substrate to be processed corresponding to an elapsed time from the start of dry etching. A sense light detection device is provided.

  According to the dry etching apparatus of the present invention, the photoluminescence light detection apparatus is used to detect the intensity of the photoluminescence light from the substrate to be processed corresponding to the elapsed time from the start of dry etching. Can do.

  Thereby, since the progress of dry etching in the substrate to be processed can be accurately observed, the end point of dry etching can be detected with high accuracy.

  Further, according to the dry etching apparatus of the present invention, photoluminescence light from the substrate to be processed is used as a method for detecting the end point of dry etching.

  Therefore, during dry etching, the product of the dry etching reaction adhering to the reaction chamber may cause fluctuations in the plasma emission due to fluctuations in the pressure in the reaction chamber, etc. Since the photoluminescence light from is hardly affected by fluctuations in plasma emission, the end point of dry etching can be detected with good reproducibility.

  In the dry etching apparatus according to the present invention, the photoluminescence light detection apparatus is preferably installed at a position overlooking the substrate to be processed.

  If it does in this way, the photoluminescence light from the whole to-be-processed substrate can be observed using a photoluminescence light detection apparatus. For this reason, since the progress of dry etching in the substrate to be processed can be accurately observed, the end point of dry etching can be detected with high accuracy.

  In the dry etching apparatus according to the present invention, it is preferable that the apparatus further includes a plasma light emission detection apparatus that detects the intensity of plasma light emission from the plasma corresponding to the elapsed time from the start of dry etching.

  In this way, the plasma emission detector can be used to observe changes in the intensity of plasma emission due to fluctuations in the pressure in the reaction chamber during dry etching, that is, fluctuations in plasma emission. it can.

  As a result, the intensity of the photoluminescence light from the substrate to be processed fluctuates in response to fluctuations in predetermined plasma emission, specifically, plasma emission that induces and emits photoluminescence light from the substrate to be processed. Can be detected.

  For this reason, since the progress of dry etching in the substrate to be processed can be observed more accurately, the end point of dry etching can be detected with higher accuracy.

  A dry etching method according to the present invention includes a substrate to be processed installed in a reaction chamber by dry etching using plasma made of a reactive gas, which is generated by supplying high-frequency power into the reaction chamber into which the reactive gas is introduced. Is a dry etching method for processing the substrate, wherein the dry etching is performed based on the intensity of the photoluminescence light from the substrate to be processed corresponding to the elapsed time from the start of the dry etching.

  According to the dry etching method of the present invention, dry etching can be performed based on the intensity of photoluminescence light from the substrate to be processed, corresponding to the elapsed time from the start of dry etching.

  As a result, dry etching can be performed while accurately grasping the progress of dry etching on the substrate to be processed, so that dry etching can be satisfactorily completed without excessively etching the substrate to be processed. Can do.

  Further, according to the dry etching method of the present invention, dry etching is performed based on the intensity of photoluminescence light from the substrate to be processed.

  Therefore, during dry etching, the product of the dry etching reaction adhering to the reaction chamber may cause fluctuations in the plasma emission due to fluctuations in the pressure in the reaction chamber, etc. Since the photoluminescence light from is not easily affected by fluctuations in plasma emission, the progress of dry etching on the substrate to be processed can be accurately grasped.

  In the dry etching method according to the present invention, it is preferable to perform dry etching further based on the intensity of plasma emission from plasma corresponding to the elapsed time from the start of dry etching.

  In this way, dry etching can be performed based on the intensity of predetermined plasma emission, specifically, plasma emission that induces and emits photoluminescence light from the substrate to be processed. .

  For this reason, since dry etching can be performed while more accurately grasping the progress of dry etching on the substrate to be processed, the dry etching is further improved without excessively performing dry etching on the substrate to be processed. Can be finished.

In the dry etching method according to the present invention, the reactive gas includes an etching gas composed of a mixed gas of a chlorine-based gas and a rare gas, and the chlorine-based gas includes a gas composed of Cl ₂ , a gas composed of SiCl ₄ , and BCl. _{It is} preferable that at least one kind of gas composed of ₃ is included, and the rare gas includes at least one kind of gas selected from Ar, He, and Xe.

  In the dry etching method according to the present invention, it is preferable that the reactive gas further includes an additive gas having plasma emission that induces and emits photoluminescence light.

  Accordingly, dry etching can be performed based on the intensity of photoluminescence light that is induced and emitted from the substrate to be processed by plasma emission.

In the dry etching method according to the present invention, the additive gas is a gas composed of N ₂ , a gas composed of CO, a gas composed of O ₂ , a gas composed of H ₂ , a gas composed of H ₂ O, and a gas composed of NH ₃ . Among these, it is preferable that at least one kind of gas is included.

  Thus, photoluminescence light can be induced to be emitted from the substrate to be processed by plasma emission from plasma (radicals or ions) derived from the additive gas.

  The semiconductor laser manufacturing method according to the present invention includes a first conductive type cladding layer, an active layer, a second conductive type first cladding layer, an etching stop layer, and a second conductive type second layer on a semiconductor substrate. A method for manufacturing a semiconductor laser in which a plurality of cladding layers are stacked in order from the bottom, including a step of forming a ridge pattern in the second cladding layer by dry etching using plasma made of a reactive gas. Is characterized in that it is performed based on the intensity of photoluminescence light stimulated and emitted from the etching stop layer in correspondence with the elapsed time from the start of dry etching.

  According to the semiconductor laser manufacturing method of the present invention, dry etching can be performed based on the intensity of photoluminescence light from the etching stop layer, corresponding to the elapsed time from the start of dry etching.

  For this reason, when the ridge pattern is formed, the dry etching can be performed while accurately grasping the progress of the dry etching in the second cladding layer, so that the etching stop layer and the first cladding are conventionally used. Since no digging portion is formed in the layer, the yield of the semiconductor laser can be improved.

  Furthermore, according to the semiconductor laser manufacturing method of the present invention, the ridge pattern can be formed using only the dry etching method without using the wet etching method.

  For this reason, a semiconductor laser having a ridge pattern having a shape excellent in symmetry and perpendicularity can be realized, so that a semiconductor laser capable of high output operation can be provided.

  Moreover, according to the method for manufacturing a semiconductor laser according to the present invention, dry etching is performed based on the intensity of photoluminescence light from the etching stop layer.

  Therefore, during dry etching, the product of the dry etching reaction adhering to the reaction chamber may cause fluctuations in the plasma emission due to fluctuations in the pressure in the reaction chamber. Since the photoluminescence light from is hardly affected by fluctuations in plasma emission, the progress of dry etching in the second cladding layer can be accurately grasped.

  In the semiconductor laser manufacturing method according to the present invention, the dry etching may be further performed based on the intensity of the plasma emission from the plasma made of the reactive gas corresponding to the elapsed time from the start of the dry etching. preferable.

  Thus, when the ridge pattern is formed, dry etching is further performed based on predetermined plasma emission, specifically, the intensity of plasma emission that induces and emits photoluminescence light from the etching stop layer. Can do.

  For this reason, when the ridge pattern is formed, the dry etching can be performed while more accurately grasping the progress of the dry etching in the second cladding layer. Since no digging portion is formed in the cladding layer, the yield of the semiconductor laser can be further improved.

  In the semiconductor laser manufacturing method according to the present invention, it is preferable that the cladding layer, the first cladding layer, and the second cladding layer are made of AlGaInP, and the active layer and the etching stop layer contain GaInP.

  In the method for producing a semiconductor laser according to the present invention, it is preferable that the dry etching is continuously performed under the adjusted conditions after the dry etching conditions are adjusted based on the intensity of the photoluminescence light.

  In this way, when the ridge pattern is formed, dry etching corresponding to the progress of dry etching in the second cladding layer can be performed.

  For example, by adjusting the dry etching conditions (specifically, the flow rate of the etching gas, etc.) immediately before the etching stop layer is completely exposed, the selection ratio of the second cladding layer to the etching stop layer can be increased. Change to high dry etching conditions.

  Accordingly, when the ridge pattern is formed, the second cladding layer can be selectively dry-etched immediately before the etching stop layer is completely exposed. In addition, since the digging portion is not formed in the first cladding layer, the yield of the semiconductor laser can be further improved.

  In the method for manufacturing a semiconductor laser according to the present invention, it is preferable to adjust the composition ratio of the material constituting the etching stop layer.

  In this way, since the band gap of the etching stop layer can be adjusted, the photoluminescence light from the etching stop layer can be controlled so as to exhibit a light emission peak in a desired wavelength region.

  Thus, the additive gas can be selected as appropriate in accordance with the wavelength (λmax) of the emission peak indicated by the photoluminescence light from the etching stop layer, so that the choice of additive gas can be expanded.

  Moreover, since the difference between the wavelength of the emission peak indicated by the photoluminescence light from the etching stop layer and the wavelength of the emission peak indicated by the photoluminescence light from the active layer can be achieved, the interference between the two can be reduced. Can do.

  For this reason, when the ridge pattern is formed, the dry etching can be performed while more accurately grasping the progress of the dry etching in the second cladding layer. Since no digging portion is formed in the cladding layer, the yield of the semiconductor laser can be further improved.

  In the dry etching apparatus according to the present invention, it is possible to detect the intensity of the photoluminescence light from the substrate to be processed corresponding to the elapsed time after the dry etching is started using the photoluminescence light detection apparatus. Therefore, the end point of dry etching can be detected with high accuracy.

  In particular, in the method of manufacturing a semiconductor laser using the dry etching apparatus according to the present invention, when the ridge pattern is formed, the photoluminescence light detector provided in the apparatus is used to dry the second cladding layer. Corresponding to the elapsed time from the start of etching, the intensity of photoluminescence light from the etching stop layer can be detected.

  Therefore, in the semiconductor laser manufacturing method using the dry etching apparatus according to the present invention, the end point of the dry etching in the second cladding layer can be accurately detected. Since no digging portion is formed in one cladding layer, the yield of the semiconductor laser can be improved.

  Furthermore, in the semiconductor laser manufacturing method using the dry etching apparatus according to the present invention, the ridge pattern can be formed using only the dry etching method without using the wet etching method.

  For this reason, since a semiconductor laser provided with a ridge pattern having a shape with excellent verticality and objectivity can be realized, a semiconductor laser capable of high output operation can be provided.

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

(First embodiment)
A dry etching apparatus according to the first embodiment of the present invention will be described below with reference to FIG.

  FIG. 1 is a cross-sectional view showing a configuration of a dry etching apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, a lower electrode 101 is provided at the bottom of the reaction chamber 100, and a substrate to be processed (not shown) is placed on the lower electrode 101. On the other hand, an upper electrode 102 is provided on the ceiling of the reaction chamber 100 so as to face the lower electrode 101 with a space for generating plasma interposed therebetween.

  The reaction chamber 100 is provided with a high-frequency power source 103, and for example, 13.56 MHz power is applied to the lower electrode 101 using the high-frequency power source 103. The reaction chamber 100 is provided with a gas inlet 104 for introducing a reactive gas into the reaction chamber 100 and a gas exhaust port 105 for discharging the reactive gas from the reaction chamber 100. .

  Further, the reaction chamber 100 is provided with a PL light emission detection device 106 and a plasma light emission detection device 107.

  The PL light emission detection device 106 detects the intensity of photoluminescence light (hereinafter referred to as PL light) from the substrate to be processed, corresponding to the elapsed time from the start of dry etching.

  On the other hand, the plasma light emission detecting device 107 detects the intensity of plasma light emission from a predetermined plasma corresponding to the elapsed time from the start of dry etching.

  The plasma emission detected using the plasma emission detector 107 is plasma emission that induces and emits PL emission from the substrate to be processed. Specifically, the plasma emission is introduced into the reaction chamber 100 through the gas inlet 104. This corresponds to plasma emission from a plasma made of a reactive gas or a plasma made of a product of a dry etching reaction.

  In the following, a dry etching method using the dry etching apparatus according to the first embodiment of the present invention, specifically, a semiconductor laser manufacturing method will be described with reference to FIGS. This will be described with reference to FIG.

  2 (a) to 2 (c) are cross-sectional views of essential steps showing a semiconductor laser manufacturing method using the dry etching apparatus according to the first embodiment of the present invention.

  FIG. 3 is a diagram showing the intensity of PL emission from the substrate to be processed corresponding to the elapsed time from the start of dry etching.

  First, as shown in FIG. 2A, an n-type clad layer 201, an active layer 202, a p-type first clad layer 203, an etching stop are formed on an n-type substrate 200 by using MOCVD. A layer (hereinafter referred to as an ES layer) 204 and a p-type second cladding layer 205 are stacked in this order from the bottom.

  Subsequently, a resist 206 patterned into a desired shape is formed on the second cladding layer 205 by using lithography and etching techniques.

  Here, the active layer 202 and the ES layer 204 are configured using a material that induces and emits PL light by absorbing light having a specific wavelength incident on the layers.

  Thereby, PL light emission can be induced to be emitted from the ES layer 204 by plasma light emission (that is, light having a specific wavelength) from a predetermined plasma.

  Next, the semiconductor substrate 200 on which a plurality of semiconductor layers (201 to 205) and the like are formed is transferred into the reaction chamber 100 (see FIG. 1 described above) in the dry etching apparatus according to the first embodiment of the present invention. A semiconductor substrate 200 on which a plurality of semiconductor layers (201 to 205) and the like are formed is placed on the lower electrode 101.

  Subsequently, a reactive gas is supplied into the reaction chamber 100 through the gas inlet 104, and high frequency power is supplied into the reaction chamber 100 using the high frequency power source 103. As a result, in the reaction chamber 100, a plasma made of a reactive gas is generated, and dry etching using the plasma is performed on the second cladding layer 205.

  In this way, dry etching of the portion of the second cladding layer 205 where the resist 206 is not present is started.

  With the start of dry etching, plasma emission from a predetermined plasma starts to enter the second cladding layer 205.

  Here, it is generally known that the proportion of light that is transmitted into the material without being absorbed in the material is proportional to the thickness of the material.

  For this reason, in the initial stage of dry etching, plasma emission from a predetermined plasma is completely absorbed in the second cladding layer 205. For this reason, the plasma emission from the predetermined plasma does not reach the ES layer 204, so that the PL emission from the ES layer 204 is not induced and emitted by the plasma emission.

  Therefore, as shown in FIG. 3, PL light emission from the ES layer 204 is not observed in the PL light emission detection device 106 in the initial stage of dry etching.

  Next, as shown in FIG. 2B, as dry etching in the second cladding layer 205 proceeds, a portion of the second cladding layer 205 where the resist 206 is not present begins to be selectively removed.

  As described above, it is generally known that the proportion of light that is transmitted into the material without being absorbed in the material is proportional to the thickness of the material.

  For this reason, as the dry etching progresses, the thickness of the portion of the second cladding layer 205 where the resist 206 is not present decreases, so that part of the plasma emission from the predetermined plasma is the second The light passes through the second cladding layer 205 and reaches the ES layer 204 without being completely absorbed by the cladding layer 205. For this reason, PL emission from the ES layer 204 starts to be stimulated and emitted by plasma emission from a predetermined plasma.

  Therefore, with the progress of dry etching, PL light emission from the ES layer 204 starts to be observed in the PL light emission detection device 106 as shown in FIG.

  Further, as the dry etching further progresses, the thickness of the portion of the second cladding layer 205 where the resist 206 does not exist is further reduced, so that the second of the plasma emission from the predetermined plasma is the second. The proportion of plasma emission that passes through the second cladding layer 205 and reaches the ES layer 204 without being absorbed in the cladding layer 205 increases.

  Therefore, with further progress of dry etching, the PL light emission detection device 106 gradually increases the intensity of PL light emission from the ES layer 204 as shown in FIG.

  Thus, as shown in FIG. 3, the intensity of PL emission from the ES layer 204 gradually increases with the progress of dry etching, and changes from the state in the region a to the state in the region b.

  Next, with further progress of dry etching, part of the second clad layer 205 where the resist 206 is not present is completely removed, and the ES layer 204 begins to be exposed.

  For this reason, as the dry etching further progresses, the thickness of the portion of the second cladding layer 205 where the resist 206 does not exist further decreases and a part of the ES layer 204 begins to be exposed. Part of the plasma emission from this plasma is directly incident on the ES layer 204 without the second cladding layer 205 interposed.

  Therefore, with further progress of dry etching, the PL emission detection device 106 rapidly increases the intensity of PL emission from the ES layer 204 as shown in FIG.

  Next, as shown in FIG. 2C, as dry etching further progresses, the portion of the second cladding layer 205 where the resist 206 is not present is completely removed. As a result, a portion of the ES layer 204 where the resist 206 is not present is completely exposed, and a ridge pattern 205 a having a desired shape can be formed on the ES layer 204.

  For this reason, in the etching state shown in FIG. 2C, all plasma emission from the predetermined plasma is directly incident on the ES layer 204 without the second cladding layer 205 interposed.

  Therefore, with further progress of dry etching, PL light emission from the ES layer 204 shows a substantially constant intensity in the PL light emission detection device 106 as shown in FIG.

  Thus, as shown in FIG. 3, the intensity of PL emission from the ES layer 204 shows a constant intensity after increasing rapidly with further progress of dry etching, and changes from the state in the region b to the region c. Changes to the state at.

  In the method of manufacturing a semiconductor laser using the dry etching apparatus according to the first embodiment of the present invention, as shown in FIG. 3, a point in time when the intensity of PL emission from the ES layer 204 increases and a certain intensity is shown. This is the end point of dry etching.

  As described above, in the dry etching apparatus according to the first embodiment of the present invention, using the PL light emission detection device 106 provided in the apparatus, corresponding to the elapsed time from the start of the dry etching, The intensity of PL emission from the ES layer 204 is detected.

  Accordingly, since the progress of dry etching in the second cladding layer 205 can be accurately observed, the end point of dry etching in the second cladding layer 205 can be detected with high accuracy.

  Further, in the dry etching apparatus according to the first embodiment of the present invention, from the second cladding layer (see FIG. 9 described above) as in the past, corresponding to the elapsed time from the start of dry etching. Instead of detecting the intensity of the plasma emission, the intensity of the PL emission from the ES layer 204 is detected as shown in FIG.

  For this reason, during dry etching, the pressure in the reaction chamber 100 may fluctuate due to the product of the dry etching reaction adhering in the reaction chamber 100, which may cause fluctuations in plasma emission. Since PL light emission from the ES layer 204 is not easily affected by fluctuations in plasma light emission, the end point of dry etching in the second cladding layer 205 can be detected with good reproducibility.

  Further, in the dry etching apparatus according to the first embodiment of the present invention, as shown in FIG. 1, the PL emission detection device 106 provided in the apparatus is installed at a position overlooking the substrate to be processed. Yes.

  Thereby, PL light emission from the entire ES layer 204 can be observed using the PL light emission detection device 106. Therefore, since the progress of dry etching in the second cladding layer 205 can be accurately observed, the end point of dry etching can be detected with high accuracy.

  Further, in the dry etching method using the dry etching apparatus according to the first embodiment of the present invention, specifically, in the method for manufacturing a semiconductor laser, the first time corresponding to the elapsed time from the start of dry etching is Based on the intensity of PL emission from the second clad layer 205, dry etching can be performed.

  Accordingly, since the dry etching can be performed while accurately grasping the progress of the dry etching in the second cladding layer 205, the dry etching can be performed without excessively performing the dry etching on the second cladding layer 205. Can be finished well.

  That is, when the ridge pattern 205a is formed, the digging portion (see FIG. 8 (d) 507 described above) is not formed in the ES layer 204 and the first clad layer 203 as in the prior art. The yield can be improved.

  Furthermore, in the semiconductor laser manufacturing method using the dry etching apparatus according to the first embodiment of the present invention, the ridge pattern 205a can be formed using only the dry etching method without using the wet etching method. it can.

  Therefore, a semiconductor laser including the ridge pattern 205a having a shape excellent in symmetry and perpendicularity can be realized, so that a semiconductor laser capable of high output operation can be provided.

  In the dry etching apparatus according to the first embodiment of the present invention, as shown in FIG. 1, the PL light emission detection apparatus 106 provided in the apparatus is such that the entire substrate to be processed is viewed from obliquely above. Although it is installed at the position, it is not limited to this position, and the PL is set in consideration of the installation position of the upper electrode 102, the coil (not shown) for generating plasma, or the antenna (not shown). What is necessary is just to select the attachment position of the light emission detection apparatus 106 suitably.

(Second Embodiment)
Hereinafter, a dry etching method using the dry etching apparatus according to the second embodiment of the present invention, specifically, a method for manufacturing a semiconductor laser will be described with reference to FIGS. This will be described with reference to FIG. 6 and FIG.

  4 (a) to 4 (d) and FIGS. 5 (a) to 5 (c) are cross-sectional views showing main steps of a semiconductor laser manufacturing method using the dry etching apparatus according to the second embodiment of the present invention. It is.

  FIG. 6 is a diagram showing the intensity of PL emission from the substrate to be processed and the intensity of plasma emission from a predetermined plasma corresponding to the elapsed time from the start of dry etching.

A curve PL shown in FIG. 6 shows a time change in the intensity of PL emission from the ES layer 204, while a curve OES shown in FIG. 6 shows a predetermined plasma (specifically, N ₂ The time change in the intensity of plasma emission from radicals) is shown.

First, as shown in FIG. 4A, an active layer formed by laminating a clad layer 201 made of n-type AlGaInP, a GaInP layer, and an AlGaInP layer on a substrate 200 made of n-type GaAs using MOCVD. 202, a first cladding layer 203 made of p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, an etching stop layer (hereinafter referred to as ES layer) 204 made of a GaInP layer, and a p-type (Al _0.7 Ga _0.3 ) _0.5 In _A second clad layer 205 made of _0.5 P and a cap layer 306 made of p-type GaAs are stacked in this order from the bottom.

  Here, the active layer 202 and the ES layer 204 are configured using a material that induces and emits PL light by absorbing light having a specific wavelength incident on the layers.

  Specifically, the ES layer 204 is configured using a material designed to exhibit a light emission peak near a wavelength of 660 nm, while the active layer 202 is designed to exhibit a light emission peak near a wavelength of 650 nm. It is constructed using materials.

  Next, as shown in FIG. 4B, after an oxide film 307 is formed on the cap layer 306, the oxide film 307 is patterned into a desired shape using lithography and etching techniques. A resist 206 is formed.

  Next, as shown in FIG. 4C, using the dry etching technique, the resist 206 is used as a mask to selectively remove a portion of the oxide film 307 where the resist 206 is not present, and then the resist 206 is removed. To do.

  Thereby, an oxide film mask 307 a patterned into a desired shape is formed on the cap layer 306.

  Next, a semiconductor substrate 200 (with a plurality of semiconductor layers (201 to 205 and 306) formed in the reaction chamber 100 (see FIG. 1 described above) in the dry etching apparatus according to the second embodiment of the present invention. 4C), the semiconductor substrate 200 on which a plurality of semiconductor layers (201 to 205 and 306) and the like are formed is placed on the lower electrode 101.

Subsequently, with the pressure in the reaction chamber 100 controlled to 1 Pa, the flow rate of SiCl ₄ gas is 10 (ml / min), the flow rate of Ar gas is 50 (ml / min), and the flow rate of N ₂ gas. Each gas is supplied into the reaction chamber 100 through the gas inlet 104 under 5 (ml / min).

  Thus, the reactive gas supplied into the reaction chamber 100 through the gas inlet 104 is configured using the etching gas and the additive gas.

The etching gas is a mixed gas of a chlorine-based gas and a rare gas. In the dry etching apparatus according to the second embodiment of the present invention, SiCl ₄ gas is used as the chlorine-based gas, and Ar gas is used as the rare gas. Used.

On the other hand, the additive gas is a gas having plasma emission that induces and emits PL emission from the ES layer 204. In the dry etching apparatus according to the second embodiment of the present invention, N ₂ gas is used as the additive gas. .

  Subsequently, the temperature of the substrate 200 installed in the reaction chamber 100 is increased to 150 (° C.), and high frequency power of 500 (W) is supplied into the reaction chamber 100 using the high frequency power source 103. As a result, a large number of plasma species including the etching gas and the additive gas are generated in the reaction chamber 100.

Among the plasma species composed of SiCl ₄ gas, Cl ^* radicals or Cl ⁺ ions react with the cap layer 306 composed of GaAs and the second cladding layer 205 composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. Chlorides, specifically AsCl _x , AlCl _x , GaCl _x , InCl _x , and PCl _x are generated and eliminated. In this way, the dry etching reaction proceeds in the cap layer 306 and the second cladding layer 205.

Here, the additive gas (specifically, N ₂ gas) supplied into the reaction chamber 100 together with the etching gas through the gas inlet 104 does not hinder the progress of the dry etching reaction.

On the other hand, among the plasma species composed of N ₂ gas, the plasma emission from the N ₂ ^* radical shows an emission peak in the vicinity of 660 nm, so that the PL emission from the ES layer 204 can be induced to be emitted.

  As described above, in the dry etching apparatus according to the second embodiment of the present invention, the cap layer 306 and the second cladding layer 205 are dry-etched using plasma made of an etching gas and made of an additive gas. PL emission from the ES layer 204 is stimulated to be emitted using plasma.

With the start of dry etching, plasma emission from a predetermined plasma (N ₂ ^* radical) starts to enter the second cladding layer 205.

  Here, it is generally known that the proportion of light that is transmitted into the material without being absorbed in the material is proportional to the thickness of the material.

Therefore, in the initial stage of dry etching, plasma emission from plasma (N ₂ ^* radical) derived from N ₂ gas is completely absorbed in the cap layer 306 and the second cladding layer 205. For this reason, plasma emission from plasma (N ₂ ^* radical) derived from N ₂ gas does not reach the ES layer 204, and PL emission from the ES layer 204 is induced and emitted by the plasma emission. There is nothing.

  Therefore, in the PL emission detection device 106 (see FIG. 1 described above) in the initial stage of dry etching, PL emission from the ES layer 204 is not observed at the etching time t1, as shown in FIG.

  Subsequently, as the dry etching of the cap layer 306 and the second cladding layer 205 proceeds, the cap layer 306 where the oxide film mask 307a does not exist is completely removed and patterned into a desired shape. Layer 306a is formed.

  Next, as shown in FIG. 4 (d), as dry etching in the second cladding layer 205 proceeds, a portion of the second cladding layer 205 where the oxide film mask 307a does not exist is selectively removed. start.

  As described above, it is generally known that the proportion of light that is transmitted into the material without being absorbed in the material is proportional to the thickness of the material.

For this reason, as the dry etching progresses, the thickness of the portion of the second cladding layer 205 where the oxide film mask 307a does not exist decreases, so that the plasma (N ₂ ^* radical) derived from the N ₂ gas is used. A part of the plasma emission is not completely absorbed in the second cladding layer 205 but passes through the second cladding layer 205 and reaches the ES layer 204. For this reason, PL light emission from the ES layer 204 starts to be stimulated and emitted by plasma light emission from plasma derived from N ₂ gas.

  Therefore, with the progress of dry etching, PL light emission from the ES layer 204 begins to be observed at the etching time t2 in the PL light emission detection device 106 (see FIG. 1 described above) as shown in FIG.

  Next, as shown in FIG. 5A, with further progress of dry etching, a portion of the second cladding layer 205 where the oxide film mask 307a does not exist is partially removed. Then, an exposed portion 204a in which a part of the ES layer 204 is exposed is formed.

For this reason, as the dry etching further progresses, the thickness of the portion of the second cladding layer 205 where the oxide film mask 307a does not exist further decreases and a part of the ES layer 204 begins to be exposed. A part of the plasma emission from the plasma (N ₂ ^* radical) derived from N ₂ gas is directly incident on the ES layer 404 without the second cladding layer 205 interposed.

  Therefore, as the dry etching further progresses, the PL emission detection device 106 (see FIG. 1 described above) rapidly increases the intensity of PL emission from the ES layer 204 at the etching time t3 as shown in FIG. Increase.

  Next, as shown in FIG. 5 (b), with further progress of dry etching, the portion of the second cladding layer 205 where the oxide film mask 307a does not exist is completely removed. As a result, a portion of the ES layer 204 where the oxide film mask 307a does not exist is completely exposed, and a ridge pattern 205a having a desired shape can be formed on the ES layer 204.

For this reason, in the etching state shown in FIG. 5B, all the plasma emission from the plasma (N ₂ ^* radical) derived from the N ₂ gas does not intervene the second cladding layer 205, and the ES layer 204 Directly incident on the inside.

  Therefore, as the dry etching further progresses, the PL emission detection device 106 (see FIG. 1 described above) has a substantially constant PL emission from the ES layer 204 at the etching time t4 as shown in FIG. Indicates strength.

  As described above, in the method for manufacturing a semiconductor laser using the dry etching apparatus according to the second embodiment of the present invention, as shown in FIG. 6, the intensity of PL emitted from the ES layer 204 is increased after the intensity is increased. That is, the etching time t4 is the end point of dry etching.

  PL light emission from the ES layer 204 shows a light emission peak in the vicinity of a wavelength of 660 nm. Using the PL light emission detector 106 (see FIG. 1 described above), as shown in FIG. Corresponding to time, the intensity of PL emission from the ES layer 204 at a wavelength of 660 nm is detected (see curve PL).

On the other hand, the plasma emission from the N ₂ ^* radical shows an emission peak near the wavelength of 654 nm, and dry etching is started using the plasma emission detector 107 (see FIG. 1 described above) as shown in FIG. Corresponding to the elapsed time from, the intensity of plasma emission from the N ₂ ^* radical at a wavelength of 654 nm is detected (see curve OES).

  Next, as shown in FIG. 5C, a current blocking layer 308 is formed on the ES layer 204 so as to cover the ridge pattern 205a, and then the oxide film mask 307a is removed to thereby remove the cap layer 306a. A current injection region (not shown) is formed in which is exposed. Subsequently, a p-electrode 309 is formed on the cap layer 306a (that is, the current injection region).

  Subsequently, an n-electrode (not shown) is formed on the clad layer 201, thereby forming a semiconductor laser having a current confinement structure.

  As described above, in the dry etching apparatus according to the second embodiment of the present invention, the ES using the PL light emission detection apparatus 106 provided in the apparatus corresponding to the elapsed time from the start of dry etching. In addition to detecting the intensity of PL emission from the layer 204, the intensity of plasma emission from a predetermined plasma is detected using the plasma emission detector 107.

Thus, the intensity of plasma emission from the plasma (N ₂ ^* radical) derived from N ₂ gas due to fluctuations in the pressure in the reaction chamber 100 during dry etching using the plasma emission detector 107. Can be observed, that is, fluctuations in plasma emission can be observed.

For this reason, it is detected that the intensity of PL light emission from the ES layer 204 varies in response to fluctuations in plasma light emission that induces and emits plasma light emission from N ₂ ^* radicals, that is, PL light emission from the ES layer 204. be able to.

  Thereby, since the progress of dry etching in the second cladding layer 205 can be observed more accurately, the end point of dry etching in the second cladding layer 205 can be detected with higher accuracy.

  Further, in the dry etching apparatus according to the second embodiment of the present invention, from the second cladding layer (see FIG. 9 described above) as in the past, corresponding to the elapsed time from the start of dry etching. Instead of detecting the intensity of the plasma emission, the intensity of the PL emission from the ES layer 204 is detected as shown in FIG.

  For this reason, during dry etching, the pressure in the reaction chamber 100 may fluctuate due to the product of the dry etching reaction adhering in the reaction chamber 100, which may cause fluctuations in plasma emission. Since PL light emission from the ES layer 204 is not easily affected by fluctuations in plasma light emission, the end point of dry etching in the second cladding layer 205 can be detected with good reproducibility.

Further, in the dry etching method using the dry etching apparatus according to the second embodiment of the present invention, specifically, in the method of manufacturing a semiconductor laser, the first time corresponding to the elapsed time from the start of dry etching is Further, dry etching is performed based on not only the intensity of PL emission from the second clad layer 205 but also the intensity of plasma emission from N ₂ ^* radicals, that is, the intensity of plasma emission that induces and emits PL emission from the ES layer 204. be able to.

For example, the intensity of PL emission from the ES layer 204 is normalized using the intensity indicated by plasma emission from N ₂ ^* radicals corresponding to the elapsed time from the start of dry etching. Thereby, it is possible to improve the SN ratio with respect to the temporal change in the intensity of PL emission from the ES layer 204.

  Thus, in the semiconductor laser manufacturing method using the dry etching apparatus according to the second embodiment of the present invention, dry etching is performed while more accurately grasping the progress of dry etching in the second cladding layer 205. Since it can be performed, the dry etching can be completed more satisfactorily without excessively dry etching the second cladding layer 205.

  That is, when the ridge pattern 205a is formed, a digging portion (see FIG. 8 (d) 507 described above) is not formed in the ES layer 204 and the first cladding layer 203 as in the prior art. The yield of laser can be further improved.

  Furthermore, in the semiconductor laser manufacturing method using the dry etching apparatus according to the second embodiment of the present invention, the ridge pattern 205a can be formed using only the dry etching method without using the wet etching method. it can.

  Therefore, a semiconductor laser including the ridge pattern 205a having a shape excellent in symmetry and perpendicularity can be realized, so that a semiconductor laser capable of high output operation can be provided.

In the semiconductor laser manufacturing method using the dry etching apparatus according to the second embodiment of the present invention, N ₂ gas is used as the additive gas supplied into the reaction chamber 100 through the gas inlet 104. The gas is not limited to N ₂ gas, and may be appropriately selected as long as it is a gas that generates plasma (ion or radical) having a light emission peak in the vicinity of PL emission (λmax = 660 nm) from the ES layer 204 made of GaInP. Can be used.

  In the following, plasma types showing emission peaks in the vicinity of a wavelength of 660 nm and their representative wavelengths will be described with reference to [Table 1].

As shown in [Table 1], when N ₂ gas, CO gas, H ₂ O gas, H ₂ gas, and NH ₃ gas are used as additive gases, plasma species (radicals or ions) made of these additive gases The plasma emission from, shows a strong emission peak in the vicinity of a wavelength of 660 nm.

  For this reason, at least one kind of these gases is selected as an additive gas, and is supplied into the reaction chamber 100 through the gas inlet 104 together with the etching gas. PL emission can be induced to be emitted.

  In the dry etching method using the dry etching apparatus according to the second embodiment of the present invention, the etching time t4 shown in FIG. 6, that is, the portion where the oxide film mask 307a is not present in the ES layer 204 is completely present. The dry etching is performed without changing the dry etching conditions, and the dry etching method according to the present invention is not limited to this. The dry etching conditions may be adjusted based on the intensity of PL emission, and the dry etching may be continued under the adjusted conditions.

  For example, the dry etching conditions (for example, the flow rate of the etching gas) are adjusted immediately before the ES layer 204 is completely exposed, that is, immediately before the etching time t3 shown in FIG.

Specifically, after the step shown in FIG. 4 (c), the flow rate of the SiCl ₄ gas is maintained at 10 (ml / min) while the pressure in the reaction chamber 100 is controlled to 1 Pa. The flow rate of Ar gas is maintained at 50 (ml / min), the flow rate of N ₂ gas is adjusted to 10 (ml / min), and each gas is supplied into the reaction chamber 100 through the gas inlet 104.

  Subsequently, the temperature of the substrate 200 installed in the reaction chamber 100 is maintained at 150 (° C.), and the high frequency power supplied into the reaction chamber 100 is adjusted to 200 (W) using the high frequency power source 103.

  In this way, by adjusting the dry etching conditions, it is possible to change the dry etching conditions so that the selectivity of the second cladding layer 205 with respect to the ES layer 204 is high.

  Therefore, when the ridge pattern 205a is formed, the second cladding layer 205 can be selectively dry-etched immediately before the ES layer 204 is completely exposed. Since the digging portion (see FIG. 8D described above) is not formed in the layer 204 and the first cladding layer 203, the yield of the semiconductor laser can be further improved.

(Third embodiment)
Hereinafter, a semiconductor laser manufacturing method using the dry etching apparatus according to the third embodiment of the present invention will be described.

  In the semiconductor laser manufacturing method using the dry etching apparatus according to the second embodiment of the present invention described above, the case where the PL emission generated from the ES layer 204 exhibits an emission peak in the vicinity of a wavelength of 660 nm has been described as an example. .

  However, the semiconductor laser manufacturing method using the dry etching apparatus according to the present invention is not limited to the case where PL emission from the ES layer exhibits an emission peak in the vicinity of a wavelength of 660 nm.

  In the dry etching apparatus according to the present invention, the additive gas supplied into the reaction chamber through the gas inlet is appropriately selected and used in accordance with the wavelength (λmax) of the emission peak indicated by the PL emission generated from the ES layer. The same effects as those of the semiconductor laser manufacturing method using the dry etching apparatus according to the first and second embodiments of the present invention described above can be obtained.

  The method for manufacturing a semiconductor laser using the dry etching apparatus according to the third embodiment of the present invention will be described below with reference to the semiconductor laser using the dry etching apparatus according to the first and second embodiments of the present invention described above. Similar to the manufacturing method, the case where the material constituting the ES layer is GaInP will be described as an example.

  For example, in the ES layer made of GaInP, the composition ratio of Ga and In is adjusted so that the Ga mixed crystal ratio is increased. Thereby, since the band gap in the ES layer can be increased, the emission peak indicated by the PL emission from the ES layer shifts to the short wavelength (˜630 nm) side.

  On the other hand, for example, in the ES layer made of GaInP, the composition ratio of Ga and In is adjusted so that the mixed crystal ratio of Ga becomes small. Thereby, since the band gap in the ES layer can be reduced, the emission peak indicated by the PL emission from the ES layer shifts to the long wavelength (˜680 nm) side.

  In this way, the band gap of the ES layer can be adjusted by adjusting the composition ratio of Ga and In in the material (GaInP) constituting the ES layer, so that PL emission from the ES layer is 630 nm to It can be controlled to show an emission peak in the wavelength region of 680 nm.

  In the following, plasma types showing emission peaks in the wavelength region of 630 nm to 680 nm and their representative wavelengths will be described with reference to [Table 2].

  [Table 2] is a table showing plasma species showing emission peaks in the wavelength region of 630 nm to 680 nm and their typical wavelengths.

As shown in [Table 2], plasma from plasma species (radicals or ions) derived from N ₂ gas, O ₂ gas, CO gas, H ₂ O gas, NH ₃ gas, H ₂ gas, and NO ₃ gas Luminescence shows a strong emission peak in the wavelength region of 630 nm to 680 nm.

  For this reason, in the dry etching apparatus according to the third embodiment of the present invention, at least one of these gases is selected as an additive gas and supplied together with the etching gas into the reaction chamber through the gas inlet.

  Thus, in the method of manufacturing a semiconductor laser using the dry etching apparatus according to the third embodiment of the present invention, PL light emission from the ES layer is caused by plasma light emission from the plasma derived from the additive gas during dry etching. Can be induced to be released.

  As described above, in the semiconductor laser manufacturing method using the dry etching apparatus according to the third embodiment of the present invention, the wavelength of the emission peak indicated by PL emission from the ES layer (λmax = 630 nm to 680 nm) is supported. Since the additive gas can be selected as appropriate, the choice of additive gas can be expanded as compared with [Table 1] described above.

  Hereinafter, the semiconductor laser manufacturing method using the dry etching apparatus according to the third embodiment of the present invention will be described by taking as an example the case where PL emission generated from the ES layer shows an emission peak in the vicinity of a wavelength of 630 nm. 4 (a) to 4 (d), FIGS. 5 (a) to 5 (c) described above, and FIG. 1 described above.

  First, similarly to the process shown in FIG. 4A described above, a plurality of semiconductor layers (201 to 205 and 306) are sequentially stacked on the semiconductor substrate 200 using the MOCVD method.

  Here, in the ES layer 204 made of GaInP formed using the MOCVD method, the PL emission from the ES layer 204 has an emission peak in the vicinity of a wavelength of 630 nm by adjusting the Ga mixed crystal ratio to 0.5. Controlled as shown.

  Next, similarly to the steps shown in FIGS. 4B and 4C, an oxide film mask 307a patterned into a desired shape is formed on the cap layer 306. Next, as shown in FIG.

  Next, a semiconductor substrate 200 (in which a plurality of semiconductor layers (201 to 205 and 306) and the like are formed in a reaction chamber 100 (see FIG. 1 described above) in a dry etching apparatus according to a third embodiment of the present invention. 4C), the semiconductor substrate 200 on which a plurality of semiconductor layers (201 to 205 and 306) and the like are formed is placed on the lower electrode 101.

Subsequently, with the pressure in the reaction chamber 100 controlled to 1 Pa, the flow rate of SiCl ₄ gas is 10 (ml / min), the flow rate of Ar gas is 50 (ml / min), and the flow rate of O ₂ gas. Each gas is supplied into the reaction chamber 100 through the gas inlet 104 at 10 (ml / min).

  Subsequently, the temperature of the substrate 200 installed in the reaction chamber 100 is increased to 150 (° C.), and high frequency power of 500 (W) is supplied into the reaction chamber 100 using the high frequency power source 103.

  As a result, a large number of plasma species (radicals or ions) composed of an etching gas and an additive gas are generated in the reaction chamber 100, and dry etching using the plasma is performed on the cap layer 306 and the second cladding layer 205. I do.

Thus, in the dry etching apparatus according to the third embodiment of the present invention, a mixed gas of SiCl ₄ gas and Ar gas is used as an etching gas, and O ₂ gas is selected and used as an additive gas.

Among the plasma species derived from O ₂ gas, plasma emission from O ₂ ^* radicals exhibits an emission peak in the vicinity of a wavelength of 628 nm, so that PL emission (λmax = 630 nm) from the ES layer 204 can be induced to be emitted. .

  As described above, in the semiconductor laser manufacturing method using the dry etching apparatus according to the third embodiment of the present invention, the band of the ES layer 204 is adjusted by adjusting the composition ratio of the material constituting the ES layer 204. Since the gap can be adjusted, the PL emission from the ES layer 204 can be controlled so as to show an emission peak in a desired wavelength region (λmax = 630 nm to 680 nm).

  Thereby, the additive gas can be appropriately selected in accordance with the wavelength (λmax) of the emission peak indicated by the PL emission from the ES layer 204, so that the choice of additive gas can be expanded.

Further, for example, when O ₂ gas is selected and used as the additive gas, the selection ratio of the second cladding layer 205 to the ES layer 204 and the second cladding layer 205 to the oxide film mask 307a during dry etching are used. The selection ratio can be improved.

  Therefore, when the ridge pattern 205a is formed, the second cladding layer 205 can be selectively dry-etched, so that the ES layer 204 and the first cladding layer 204 are dug as in the conventional case. Since the portion (see FIG. 8 (d) 507 described above) is not formed, the yield of the semiconductor laser can be further improved.

  Further, in the method of manufacturing a semiconductor laser using the dry etching apparatus according to the third embodiment of the present invention, the wavelength of the emission peak (λmax = 630 nm) indicated by the PL emission from the ES layer 204 is Since the difference from the emission peak wavelength (λmax = 660 nm) exhibited by PL emission can be achieved, the interference between the two can be reduced.

  Accordingly, the progress of dry etching in the second cladding layer 205 can be more accurately observed using the PL emission detection device 106 (see FIG. 1 described above). The end point of dry etching can be detected with higher accuracy.

  Therefore, when the ridge pattern 205a is formed, the dry etching can be performed while more accurately grasping the progress of the dry etching in the second cladding layer 205. Since the digging portion (see FIG. 8 (d) 507 described above) is not formed in the first cladding layer 203, the yield of the semiconductor laser can be further improved.

  Furthermore, in the semiconductor laser manufacturing method using the dry etching apparatus according to the third embodiment of the present invention, the ridge pattern 205a can be formed using only the dry etching method without using the wet etching method. it can.

  Therefore, a semiconductor laser including the ridge pattern 205a having a shape excellent in symmetry and perpendicularity can be realized, so that a semiconductor laser capable of high output operation can be provided.

  Although the semiconductor laser manufacturing method using the dry etching apparatus according to the first to third aspects of the present invention has been described using GaInP as the material constituting the ES layer, the present invention is not limited to this. Alternatively, AlInP may be used as a material constituting the ES layer.

  Since PL light emission generated from the ES layer made of AlInP shows a light emission peak in the wavelength region of 510 nm to 580 nm, the PL light emission from the ES layer is stimulated to be emitted by plasma light emission showing the light emission peak in the wavelength region of 510 to 580 nm. be able to.

  In the following, plasma types showing emission peaks in the wavelength region of 510 nm to 580 nm and their representative wavelengths will be described with reference to [Table 3].

  [Table 3] is a table showing plasma species showing emission peaks in the wavelength region of 510 nm to 580 nm and their typical wavelengths.

As shown in [Table 3], plasma emission from plasma species (radicals or ions) derived from N ₂ gas, O ₂ gas, CO gas, H ₂ O gas, NH ₃ gas, and He gas is 510 nm to A strong emission peak is shown in the wavelength region of 580 nm.

  For this reason, at least one of these gases is selected as an additive gas, and is supplied into the reaction chamber through the gas inlet together with the etching gas, so that the plasma derived from the additive gas can be used during dry etching. The PL emission from the ES layer made of AlInP can be induced and emitted by the plasma emission.

  As described above, even when AlInP is used as a material constituting the ES layer, a semiconductor laser using the dry etching apparatus according to the first to third embodiments of the present invention can be selected by appropriately selecting a desired additive gas. The same effects as those of the manufacturing method can be obtained.

  Moreover, in the manufacturing method of the semiconductor laser using the dry etching apparatus according to the first to third embodiments of the present invention, it has been described using a red semiconductor laser, but the present invention is not limited to this, An infrared semiconductor laser using AlGaAs as a material constituting the active layer and the ES layer may be used.

  Since PL light emission generated from the ES layer made of AlGaAs shows a light emission peak in the wavelength region of 730 nm to 800 nm, that is, in the infrared region, plasma light emission showing a light emission peak in the wavelength region of 730 to 800 nm causes the emission from the ES layer. PL emission can be induced to be emitted.

  In the following, plasma types showing emission peaks in the wavelength region of 730 nm to 800 nm and typical wavelengths thereof will be described with reference to [Table 4].

  [Table 4] is a table showing the plasma types showing the emission peaks in the wavelength region of 730 nm to 800 nm and their typical wavelengths.

As shown in [Table 4], plasma emission from plasma species (radicals or ions) derived from N ₂ gas, H ₂ O gas, O ₂ gas, CO gas, and Ar gas is in the wavelength range of 730 nm to 800 nm. Shows a strong emission peak.

  For this reason, at least one of these gases is selected as an additive gas, and supplied into the reaction chamber through the gas inlet together with the etching gas, so that the PL from the ES layer made of AlGaAs can be obtained during dry etching. Luminescence can be induced to be emitted.

  Thus, even when an infrared semiconductor laser is used, by appropriately selecting a desired additive gas, a method for manufacturing a semiconductor laser using the dry etching apparatus according to the first to third embodiments of the present invention, and Similar effects can be obtained.

  In the semiconductor laser manufacturing method using the dry etching apparatus according to the first to third embodiments of the present invention, plasma (radical or ion) made of an additive gas is used as the light that induces and emits PL emission from the ES layer. However, the present invention is not limited to this, and plasma emission from plasma made of a product of a dry etching reaction may be used.

  In the dry etching method using the dry etching apparatus according to the first to third embodiments of the present invention, the method for forming the ridge pattern in the semiconductor laser has been described as a specific example, but the present invention is not limited thereto. It will never be done.

  Since the dry etching apparatus according to the present invention can accurately detect the end point of dry etching, it is useful for a method of manufacturing a semiconductor laser capable of high output operation.

It is sectional drawing which shows the structure of the dry etching apparatus which concerns on the 1st Embodiment of this invention. (a)-(c) is principal part process sectional drawing which shows the manufacturing method of a semiconductor laser using the dry etching apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the intensity | strength of PL light emission from a to-be-processed substrate corresponding to the elapsed time after dry etching was started. (a)-(d) is principal part process sectional drawing which shows the manufacturing method of a semiconductor laser using the dry etching apparatus which concerns on the 2nd Embodiment of this invention. (a)-(c) is principal part process sectional drawing which shows the manufacturing method of a semiconductor laser using the dry etching apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the intensity | strength of PL light emission from a to-be-processed substrate and the intensity | strength of plasma light emission from predetermined plasma corresponding to the elapsed time after the dry etching was started. It is sectional drawing which shows the structure of the conventional dry etching apparatus. It is principal part process sectional drawing which shows the manufacturing method of a semiconductor laser using the conventional dry etching apparatus. It is a figure which shows the intensity | strength of the plasma emission from a to-be-processed substrate corresponding to the elapsed time after the dry etching was started. It is principal part process sectional drawing which shows the manufacturing method of the semiconductor laser which used together using the dry etching method and the wet etching method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reaction chamber 101 Lower electrode 102 Upper electrode 103 High frequency power supply 104 Gas introduction port 105 Gas exhaust port 106 PL light emission detection device 107 Plasma light emission detection device 200 Substrate 201 Cladding layer 202 Active layer 203 First cladding layer 204 Etching stop layer (ES layer)
205 Second Cladding Layer 205a Ridge Pattern 206 Resist 306 Cap Layer 306a Patterned Cap Layer 307 Oxide Film 307a Oxide Film Mask 308 Current Block Layer 309 P Electrode 400 Reaction Chamber 401 Lower Electrode 402 Upper Electrode 403 High Frequency Power Supply 404 Gas Inlet 405 Gas exhaust port 406 PL emission detector 500 Substrate 501 Cladding layer 502 Active layer 503 First cladding layer 504 Etching stop layer (ES layer)
505 Second cladding layer 505a Ridge pattern 505b Second cladding layer 505c Ridge pattern

Claims (13)

A dry etching apparatus for processing a substrate to be processed installed in the reaction chamber by dry etching using plasma made of the reactive gas generated by supplying high-frequency power into the reaction chamber into which the reactive gas is introduced. There,
A dry etching apparatus comprising: a photoluminescence light detection device that detects an intensity of photoluminescence light from the substrate to be processed corresponding to an elapsed time after the dry etching is started.   The dry etching apparatus according to claim 1, wherein the photoluminescence light detection apparatus is installed at a position overlooking the substrate to be processed.   2. The dry etching apparatus according to claim 1, further comprising a plasma light emission detection device that detects an intensity of plasma light emission from the plasma in correspondence with an elapsed time from the start of the dry etching. A dry etching method for processing a substrate to be processed installed in the reaction chamber by dry etching using plasma made of the reactive gas generated by supplying high-frequency power into the reaction chamber into which the reactive gas has been introduced. There,
A dry etching method, wherein the dry etching is performed based on an intensity of photoluminescence light from the substrate to be processed corresponding to an elapsed time from the start of the dry etching.   5. The dry etching method according to claim 4, wherein the dry etching is performed further based on an intensity of plasma emission from the plasma corresponding to an elapsed time from the start of the dry etching. The reactive gas includes an etching gas composed of a mixed gas of a chlorine-based gas and a rare gas,
The chlorine-based gas includes at least one kind of gas selected from a gas composed of Cl ₂ , a gas composed of SiCl ₄ , and a gas composed of BCl ₃ ,
5. The dry etching method according to claim 4, wherein the rare gas includes at least one kind of gas selected from the group consisting of Ar gas, He gas, and Xe gas.   The dry etching method according to claim 6, wherein the reactive gas further includes an additive gas having plasma emission that induces and emits the photoluminescence light. The additive gas includes at least one gas selected from the group consisting of N ₂ gas, CO gas, O ₂ gas, H ₂ gas, H ₂ O gas, and NH ₃ gas. The dry etching method according to claim 7, further comprising: On a semiconductor substrate, a first conductivity type cladding layer, an active layer, a second conductivity type first cladding layer, an etching stop layer, and a second conductivity type second cladding layer are laminated in order from the bottom. A method for manufacturing a semiconductor laser, comprising:
Including a step of forming a ridge pattern in the second cladding layer by dry etching using plasma of a reactive gas,
The dry etching is performed based on the intensity of photoluminescence light stimulated and emitted from the etching stop layer corresponding to the elapsed time from the start of the dry etching. Method.   The dry etching is further performed based on the intensity of plasma emission from the plasma made of the reactive gas corresponding to the elapsed time from the start of the dry etching. Semiconductor laser manufacturing method. 10. The semiconductor laser according to claim 9, wherein the cladding layer, the first cladding layer, and the second cladding layer are made of AlGaInP, and the active layer and the etching stop layer contain GaInP. Manufacturing method.   10. The semiconductor laser according to claim 9, wherein the dry etching is performed under the adjusted conditions after adjusting the conditions of the dry etching based on the intensity of the photoluminescence light. Production method.   The method for manufacturing a semiconductor laser according to claim 9, wherein a composition ratio of a material constituting the etching stop layer is adjusted.

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