JP3978341B2 - Light receiving element and optical pickup section - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a light receiving element.And optical pickup sectionAbout.
[0002]
[Prior art]
  Conventionally, an optical pickup unit provided in an optical disk device condenses and irradiates the emitted light of a semiconductor laser onto a disk with a lens, and reflects reflected light whose light intensity is modulated by a data part written on the disk. Light is received by the light receiving element. From the output signal of the light receiving element, the signal processing circuit detects a data signal written on the disk and also detects a focus signal and a servo signal. The optical disk device controls the focal point of the lens based on the focus signal, and controls the condensing position of the laser beam on the disk based on the servo signal.
[0003]
  FIG. 7 is a cross-sectional view of a conventional light receiving element provided in the optical disc apparatus. In this light receiving element, a P-type semiconductor layer 702 is formed on a first P-type diffusion layer 701 formed on a semiconductor substrate 700, and an N-type diffusion layer 703 is formed on a surface portion of the P-type semiconductor layer 702. A light receiving unit is configured. An antireflection film 707 composed of a silicon oxide layer 705 and a silicon nitride layer 706 is provided on the light receiving portion in a region where light on the surface of the light receiving element is incident. The thickness of the silicon oxide layer 705 and the thickness of the silicon nitride layer 706 are set such that the reflectance of the antireflection film 707 is low with respect to incident light having a predetermined wavelength. That is, when the silicon oxide layer 705 has a refractive index of 1.47 and the silicon nitride layer 706 has a refractive index of 2.07, the silicon oxide layer 705 has a thickness of 23 nm and the silicon nitride layer 706 has a thickness of 23 nm. The layer thickness is set to 25 nm, and the reflectance of the antireflection film 707 is set to 5% with respect to incident light having a wavelength of 405 nm.
[0004]
  In the conventional light receiving element, a protective transparent resin may be coated on the surface of the P-type semiconductor layer 702 and the surface of the antireflection film 707 depending on usage.
[0005]
[Problems to be solved by the invention]
  However, when the conventional light receiving element is coated with the transparent resin, the reflectance with respect to the incident light of the transparent resin and the antireflection film 707 is larger than the reflectance with respect to the incident light of the antireflection film 707 alone. There is a problem of becoming. Specifically, when the light receiving element of FIG. 7 is coated with a transparent resin, the reflectance of the antireflection film 707 with respect to the incident light is 5%, but the reflection between the transparent resin and the antireflection film 707 with respect to the incident light. The rate becomes 22%, and the reflectivity for incident light increases by 17%. Usually, in order to make this increase in reflectance smaller, an antireflection coating is applied to the resin surface. However, in this case as well, the reflectance can be reduced only to a minimum of 17%. That is, the reflectance with respect to incident light always increases by 13% or more. More specifically, the reflectance when a transparent resin is coated is expressed by the following equation.
100− (100−A) × (100−B) ÷ 100 (%)
A: Reflectance of resin surface (%), B: Reflectance of resin and antireflection film interface (%)
Therefore, as in the above equation, the reflectance when the transparent resin is coated is determined by the reflectance of the resin surface and the reflectance of the interface between the resin and the antireflection film. Here, the reflectance of the resin surface is 5% regardless of the antireflection film structure, and can be reduced to at least 0% by applying an antireflection coating on the resin surface. The reflectance value of 17% is for this case. Therefore, the reflectance is at least 17%, and the reflectance with respect to the incident light always increases by 13% or more. If the reflectance with respect to the incident light to the light receiving element is different to this extent, the value of the signal output from the light receiving element when light of the same intensity is incident differs depending on whether or not the transparent resin is coated. Therefore, it is necessary to change the configuration of the signal processing circuit that processes the signal from the light receiving element depending on whether or not the transparent resin is coated. In other words, even with the same light receiving element, it is necessary to prepare two signal processing circuits depending on the presence or absence of the coating of the transparent resin, so that it takes time to design the signal processing circuit, and manufacturing the signal processing circuit There is a problem that costs increase.
[0006]
  In addition, since the reflectance with respect to the incident light varies depending on the presence or absence of the coating of the transparent resin, the performance test performed before shipping the product needs to be performed after the coating of the transparent resin. There is a problem that labor and cost in the performance test increase.
[0007]
  In the light receiving element of FIG. 7, when the thickness of the silicon oxide layer 705 is 40 nm and the thickness of the silicon nitride layer 706 is 33 nm, the difference in reflectance due to the presence or absence of the transparent resin coating can be suppressed to within 5%. it can. However, since the reflectance of the antireflection film 707 in this case becomes 30% or more, the sensitivity of the light receiving element is lowered. If the sensitivity is low, a sufficient S / N ratio cannot be obtained, causing a signal reading error. Further, the light receiving element with a built-in circuit has a problem that the operation speed becomes slower as the S / N ratio becomes smaller. The above problem becomes conspicuous when using short-wavelength light whose theoretical sensitivity is low. When a light receiving element with a built-in circuit was actually created and light having a wavelength of 400 nm was examined as signal light, the reflectance was It was found that it was necessary to keep it below 15%.
[0008]
  Accordingly, an object of the present invention is to provide a light receiving element in which the reflectance with respect to incident light hardly changes between the case where the transparent resin is coated and the case where the transparent resin is not disposed, and the reflectance can be reduced.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the light receiving element of the present invention comprises:,lightIn the light receiving element having an antireflection film in the region where
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, and the refractive index of the first silicon oxide layer is n1.The refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3. The refractive index of the second silicon nitride layer is n4.As
  The thickness of the first silicon oxide layer is λ / (25 · n1) nm or more and λ / (11 · n1) nm or less.Thus, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, the thickness of the second silicon oxide layer is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer is Is λ / (4 · n4) nmIt is characterized by that.
[0010]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance test work can be simplified.
[0011]
  The light receiving element of the present invention is a light receiving element having an antireflection film in a region where light enters,
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, and the refractive index of the first silicon nitride layer is n2.The refractive index of the first silicon oxide layer is n1, the refractive index of the second silicon oxide layer is n3, and the refractive index of the second silicon nitride layer is n4.As
  The thickness of the first silicon nitride layer is not less than λ / (7 · n2) nm and not more than λ / (5 · n2) nm.Thus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the second silicon oxide layer is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer. Is λ / (4 · n4) nmIt is characterized by that.
[0012]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance test work can be simplified.
[0013]
  The light receiving element of the present invention is a light receiving element having an antireflection film in a region where light enters,
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, and the refractive index of the second silicon oxide layer is n3.The refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon nitride layer is n4.As
  The thickness of the second silicon oxide layer is 19λ / (93 · n3) nm or more and 2λ / (7 · n3) nm or less.Thus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon nitride layer is Is λ / (4 · n4) nmIt is characterized by that.
[0014]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance test work can be simplified.
[0015]
  The light receiving element of the present invention is a light receiving element having an antireflection film in a region where light enters,
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, and the refractive index of the second silicon nitride layer is n4.Above The refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3.As
  The thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more4λ / (13・ N4) nm or lessThus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon oxide layer. Is λ / (4 · n3) nmIt is characterized by that.
[0016]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance test work can be simplified.
[0017]
  The light receiving element of the present invention is a light receiving element having an antireflection film in a region where light enters,
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3. Yes, above2Assuming that the refractive index of the silicon nitride layer is n4,
  The thickness of the first silicon oxide layer is λ / (25 · n1) nm or more and λ / (11 · n1) nm or less,
  The thickness of the first silicon nitride layer is λ / (7 · n2) nm or more and λ / (5 · n2) nm or less,
  The thickness of the second silicon oxide layer is 19λ / (93 · n3) nm or more and 2λ / (7 · n3) nm or less,
  The thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more4λ / (13N4) It is characterized by being nm or less.
[0018]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance test work can be simplified.
[0019]
  The light receiving element of the present invention is a light receiving element having an antireflection film in a region where light enters,
  The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
  The wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3. Yes, above2Assuming that the refractive index of the silicon nitride layer is n4,
  The thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon oxide layer is λ. / (4 · n3) nm2The thickness of the silicon nitride layer is λ / (4 · n4) nm.
[0020]
  According to the above configuration, the difference in reflectance of incident light to the light receiving element can be reliably reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. As a result, in the performance test of the product, the reflectance of the light receiving element in which the resin is arranged can be predicted almost accurately by measuring the reflectance of the light receiving element in which the resin is not arranged. Performance testing can be simplified.
[0021]
  BookInvention lightPickup partIs the light receiving elementChildPrepare.
[0022]
  According to the above-described configuration, the same signal processing circuit is used for light transmission regardless of whether or not the resin is disposed on the antireflection film included in the light receiving element.Pickup partThis light can be configuredPickup partCan be made cheaper.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0024]
  FIG. 1 is a sectional view showing a light receiving element according to the first embodiment of the present invention. In the present embodiment, descriptions of contacts, metal wirings, and interlayer insulating films formed after the contact process are omitted.
[0025]
  This light receiving element has an impurity concentration of 1E18 cm on the silicon substrate 100 in order.^-3P-type diffusion layer 101 having a thickness of about 1 μm and an impurity concentration of 1E13 to 1E16 cm^-3And a P-type semiconductor layer 102 having a thickness of about 10 to 20 μm. On the surface portion of the P-type semiconductor layer 102, the impurity concentration in the vicinity of the surface is 1E17 to 1E20 cm.^-3About N-type diffusion layer 103 is formed to constitute a light receiving portion. The impurity forming the N-type diffusion layer 103 may be any element such as arsenic, phosphorus, and antimony as long as it is a V-valent element.
[0026]
  P-type diffusion layers 104 and 104 for making contact with the P-type diffusion layer 101 from the surface of the P-type semiconductor layer 102 are formed on the left and right sides of the P-type semiconductor layer 102 in FIG. The impurity forming the P-type diffusion layer 104 may be any element such as boron or indium as long as it is a valent element.
[0027]
  An antireflection film 109 is disposed on the P-type semiconductor layer 102 and on the light receiving portion. The antireflection film 109 is composed of four layers of a first silicon oxide layer 105, a first silicon nitride layer 106, a second silicon oxide layer 107, and a second silicon nitride layer 108 in order from the side closer to the light receiving portion. Yes. Each layer constituting the antireflection film 109 is formed by a normal silicon process. The refractive index of the first silicon oxide layer 105 is n1, the refractive index of the first silicon nitride layer 106 is n2, the refractive index of the second silicon oxide layer 107 is n3, and the refractive index of the second silicon nitride layer 108 is n4. When the wavelength of light incident on the light receiving element is λ nm, the thickness of the first silicon oxide layer 105 is λ / (17 · n1) nm, and the thickness of the first silicon nitride layer 106 is λ / (6 N2) nm, the thickness of the second silicon oxide layer 107 is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer 108 is λ / (4 · n4) nm. Specifically, the first and second silicon oxide layers 105 and 107 have a refractive index of 1.47, the first and second silicon nitride layers 106 and 108 have a refractive index of 2.07, and When the wavelength of incident light is 405 nm, the thickness of the first silicon oxide layer 105 is 16 nm, the thickness of the first silicon nitride layer 106 is 33 nm, the thickness of the second silicon oxide layer 107 is 69 nm, and the second The thickness of the silicon nitride layer 108 is 49 nm.
[0028]
  With respect to the light receiving element having the above structure, the change in reflectance of light incident on the light receiving element was measured depending on whether or not the antireflection film 109 was coated with a transparent resin. Here, the transparent resin is an epoxy resin, the refractive index is 1.55, and the antireflection film 109 is formed to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%. The light incident on the light receiving element is light having a wavelength of 405 nm.
[0029]
  According to the experiment, it has been confirmed that the light receiving element can reduce the reflectance with respect to the incident light to 3% or less in both cases where the transparent resin is coated and not coated. In the light receiving element, the reflectance of the transparent resin and the antireflection film 109 with respect to the incident light is larger than the reflectance of the antireflection film 109 alone with respect to the incident light, and the difference in reflectance is 3 % Or less. Therefore, the value of the output signal with respect to incident light having the same intensity is approximately the same in the case where the transparent resin is disposed and in the case where the transparent resin is not disposed. Therefore, it is not necessary to change the configuration of the signal processing circuit of the light receiving element between when the transparent resin is disposed and when it is not disposed as in the prior art. As a result, it is only necessary to prepare one signal processing circuit for the light receiving element regardless of the presence or absence of the coating of the transparent resin. Therefore, the signal processing circuit of the light receiving element can be formed at low cost. The light receiving element has little difference between the reflectance when coated with transparent resin and the reflectance when not coated. Therefore, in the performance test after the light receiving element is completed, the light receiving element that is not coated with transparent resin is tested. Then, the test result of the light receiving element coated with the transparent resin can be predicted almost accurately. Therefore, since the performance test can be performed before coating the transparent resin, the performance test can be simplified.
[0030]
  In the above embodiment, the incident light of the light receiving element may have a wavelength other than 405 nm, and the thickness of the first silicon oxide layer 105 is λ / (17 · n1) nm based on the wavelength λ of the incident light. The thickness of the first silicon nitride layer 106 is λ / (6 · n2) nm, the thickness of the second silicon oxide layer 107 is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer 108 is λ. What is necessary is just to comprise an anti-reflective film to / (4 * n4) nm.
[0031]
  In the above-described embodiment, the antireflection film 109 is a part of the surface of the P-type semiconductor layer 102 and is disposed on the light receiving portion 103. However, the antireflection film 109 may be disposed on the entire surface of the P-type semiconductor layer 102. .
[0032]
  (Second Embodiment)
  The light receiving element of the second embodiment of the present invention has the same structure as the light receiving element of the first embodiment, and will be described with reference to FIG. In the present embodiment, when the transparent resin is coated on the antireflection film 109 of the light receiving element and when the transparent resin is not coated, among the four layers constituting the antireflection film 109 included in the light receiving element, The thickness of the first silicon oxide layer 105 was changed from 0 to λ / (5 · n1) nm. Changes in the reflectance of the antireflection film 109 and the transparent resin when the thickness of the first silicon oxide layer 105 was changed, and changes in the reflectance of the antireflection film 109 were measured. The thickness of the anti-reflection film 109 other than the first silicon oxide layer 105 is λ / (6 · n2) nm for the first silicon nitride layer 106 and λ / (4 for the second silicon oxide layer 107. N3) nm, and the second silicon nitride layer 108 is λ / (4 · n4) nm. Here, λ is the wavelength of incident light, n1 is the refractive index of the first silicon oxide layer 105, n2 is the refractive index of the first silicon nitride layer 106, and n3 is the refractive index of the second silicon oxide layer 107. N4 is the refractive index of the second silicon nitride layer 108. The transparent resin was an epoxy resin, the refractive index was 1.55, and was formed on the antireflection film 109 to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%.
[0033]
  FIG. 2 is a diagram showing measurement results of the reflectance of the antireflection film 109 and the transparent resin and the reflectance of the antireflection film 109 when the thickness of the first silicon oxide layer 105 is changed. In FIG. 2, the horizontal axis represents the thickness of the first silicon oxide layer 105, and the vertical axis represents the reflectance of the antireflection film 109 and the transparent resin, and the reflectance of the antireflection film 109. As can be seen from FIG. 2, the light receiving element of the present embodiment has a transparent resin by setting the thickness of the first silicon oxide layer 105 to λ / (25 · n1) nm or more and λ / (11 · n1) nm or less. It can be seen that the difference in reflectance with respect to incident light can be reduced to 5% or less with and without coating. In particular, when the thickness of the first silicon oxide layer 105 is λ / (17 · n1) nm, the difference in reflectance with respect to incident light between when the transparent resin is coated and when it is not coated can be minimized. When the thickness of the first silicon oxide layer 105 is not less than λ / (25 · n1) nm and not more than λ / (11 · n1) nm, the incident light can be used regardless of whether the transparent resin is coated or not. It can be seen that the reflectance with respect to can be reduced to 15% or less.
[0034]
  Specifically, when the wavelength of incident light is 405 nm, the refractive index of the first and second silicon oxide layers is 1.47, and the refractive index of the first and second silicon nitride layers is 2.07. If the thickness of the first silicon nitride layer 106 is 33 nm, the thickness of the second silicon oxide layer 107 is 69 nm, and the thickness of the second silicon nitride layer 108 is 49 nm, By setting the thickness to 11 nm or more and 25 nm or less, the difference in reflectance with respect to incident light of the light receiving element can be reduced to 5% or less depending on whether or not the transparent resin is coated.
[0035]
  According to the light receiving element of this embodiment, the difference in reflectance with respect to incident light can be reduced to 5% or less depending on whether or not the transparent resin is coated. This eliminates the need to change the circuit configuration of the signal processing circuit for processing the signal from the light receiving element depending on whether the transparent resin is coated or not as in the prior art. Therefore, the light receiving element can reduce the manufacturing cost of the signal processing circuit. In addition, the light receiving element has a signal output value corresponding to incident light of the same power, with and without coating with a transparent resin, so the transparent resin is coated in the performance test of the product. By measuring the reflectance of the antireflection film 109 in the absence, the reflectance between the antireflection film 109 and the transparent resin after coating with the transparent resin can be predicted almost accurately. Therefore, the performance test work can be simplified.
[0036]
  (Third embodiment)
  The light receiving element of the third embodiment of the present invention also has the same structure as the light receiving element of the first embodiment, and will be described with reference to FIG. In the present embodiment, when the transparent resin is coated on the antireflection film 109 of the light receiving element and when the transparent resin is not coated, among the four layers constituting the antireflection film 109 included in the light receiving element, The thickness of the first silicon nitride layer 106 was changed between λ / (10 · n2) nm and λ / (4 · n2) nm. Changes in the reflectance of the antireflection film 109 and the transparent resin when the thickness of the first silicon nitride layer 106 was changed, and changes in the reflectance of the antireflection film 109 were measured. The thickness of the layers other than the first silicon nitride layer 106 constituting the antireflection film 109 is λ / (17 · n1) nm for the first silicon oxide layer 105 and λ / (4 for the second silicon oxide layer 107. N3) nm, and the second silicon nitride layer 108 is λ / (4 · n4) nm. Here, λ is the wavelength of incident light, n1 is the refractive index of the first silicon oxide layer 105, n2 is the refractive index of the first silicon nitride layer 106, and n3 is the refractive index of the second silicon oxide layer 107. N4 is the refractive index of the second silicon nitride layer 108. The transparent resin was an epoxy resin, the refractive index was 1.55, and was formed on the antireflection film 109 to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%.
[0037]
  FIG. 3 is a diagram showing measurement results of the reflectance of the antireflection film 109 and the transparent resin and the reflectance of the antireflection film 109 when the thickness of the first silicon nitride layer 106 is changed. In FIG. 3, the horizontal axis represents the thickness of the first silicon nitride layer 106, and the vertical axis represents the reflectance of the antireflection film 109 and the transparent resin, and the reflectance of the antireflection film 109. As can be seen from FIG. 3, the light receiving element of the present embodiment has a transparent resin by setting the thickness of the first silicon nitride layer 106 to λ / (7 · n2) nm or more and λ / (5 · n2) nm or less. It can be seen that the difference in reflectance with respect to incident light can be reduced to 5% or less with and without coating. In particular, in the light receiving element of this embodiment, when the thickness of the first silicon nitride layer 106 is λ / (6 · n2) nm, the difference in reflectance with respect to incident light between when the transparent resin is coated and when it is not coated. Can be minimized. In the case where the thickness of the first silicon nitride layer 106 is λ / (7 · n2) nm or more and λ / (5 · n2) nm or less, the incident light is applied regardless of whether the transparent resin is coated or not. It can be seen that the reflectance with respect to can be reduced to 15% or less.
[0038]
  Specifically, when the wavelength of incident light is 405 nm, the refractive index of the first and second silicon oxide layers is 1.47, and the refractive index of the first and second silicon nitride layers is 2.07. Assuming that the thickness of the first silicon oxide layer 105 is 16 nm, the thickness of the second silicon oxide layer 107 is 69 nm, and the thickness of the second silicon nitride layer 108 is 49 nm, By making the thickness 28 nm or more and 39 nm or less, the difference in reflectance with respect to incident light of the light receiving element can be reduced to 5% or less depending on whether or not the transparent resin is coated.
[0039]
  According to the light receiving element of the present embodiment, there is no need to change the circuit configuration of the signal processing circuit for processing the signal from the light receiving element between when the transparent resin is coated and when the transparent resin is not coated. Therefore, the manufacturing cost of the signal processing circuit can be reduced. In the product performance test, the light receiving element measures the reflectance of the antireflection film 109 in a state where the transparent resin is not coated, so that the antireflection film 109 and the transparent resin after coating the transparent resin Can be predicted almost accurately. Therefore, the performance test work can be simplified.
[0040]
  (Fourth embodiment)
  The light receiving element of the fourth embodiment of the present invention also has the same structure as the light receiving element of the first embodiment, and will be described with reference to FIG. In the present embodiment, when the transparent resin is coated on the antireflection film 109 of the light receiving element and when the transparent resin is not coated, among the four layers constituting the antireflection film 109 included in the light receiving element, The thickness of the second silicon oxide layer 107 was changed from 5 · λ / (28 · n3) nm to 9 · λ / (28 · n3) nm. Changes in the reflectivity of the antireflection film 109 and the transparent resin when the thickness of the second silicon oxide layer 107 was changed, and changes in the reflectivity of the antireflection film 109 were measured. The thickness of the layers other than the second silicon oxide layer 107 constituting the antireflection film 109 is λ / (17 · n1) nm for the first silicon oxide layer 105 and λ / (6 for the first silicon nitride layer 106. N2) nm, and the second silicon nitride layer 108 is λ / (4 · n4) nm. Here, λ is the wavelength of incident light, n1 is the refractive index of the first silicon oxide layer 105, n2 is the refractive index of the first silicon nitride layer 106, and n3 is the refractive index of the second silicon oxide layer 107. N4 is the refractive index of the second silicon nitride layer 108. The transparent resin was an epoxy resin, the refractive index was 1.55, and was formed on the antireflection film 109 to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%.
[0041]
  FIG. 4 is a diagram showing measurement results of the reflectance of the antireflection film 109 and the transparent resin and the reflectance of the antireflection film 109 when the thickness of the second silicon oxide layer 107 is changed. In FIG. 4, the horizontal axis represents the thickness of the second silicon oxide layer 107, and the vertical axis represents the reflectance of the antireflection film 109 and the transparent resin, and the reflectance of the antireflection film 109. As can be seen from FIG. 4, in the light receiving element of this embodiment, the thickness of the second silicon oxide layer 107 is 19 · λ / (93 · n3) nm or more and 2 · λ / (7 · n3) nm or less. Thus, it can be seen that the difference in reflectance with respect to incident light can be reduced to 5% or less depending on whether or not the transparent resin is coated. In particular, in the light receiving element of the present embodiment, when the thickness of the first silicon nitride layer 106 is λ / (4 · n3) nm, a difference in reflectance with respect to incident light between when the transparent resin is coated and when not coated. Can be minimized. When the thickness of the second silicon oxide layer 107 is 19 · λ / (93 · n3) nm or more and 2 · λ / (7 · n3) nm or less, the transparent resin is coated or not. It can also be seen that the reflectivity for incident light can be reduced to 15% or less.
[0042]
  Specifically, when the wavelength of incident light is 405 nm, the refractive index of the first and second silicon oxide layers is 1.47, and the refractive index of the first and second silicon nitride layers is 2.07. Assuming that the thickness of the first silicon oxide layer 105 is 16 nm, the thickness of the first silicon nitride layer 106 is 33 nm, and the thickness of the second silicon nitride layer 108 is 49 nm, By setting the thickness to 56 nm to 79 nm, the difference in reflectance with respect to incident light of the light receiving element can be reduced to 5% or less depending on whether or not the transparent resin is coated.
[0043]
  According to the light receiving element of the present embodiment, there is no need to change the circuit configuration of the signal processing circuit for processing the signal from the light receiving element between when the transparent resin is coated and when the transparent resin is not coated. Therefore, the manufacturing cost of the signal processing circuit can be reduced. In the product performance test, the light receiving element measures the reflectance of the antireflection film 109 in a state where the transparent resin is not coated, so that the antireflection film 109 and the transparent resin after coating the transparent resin Can be predicted almost accurately. Therefore, the performance test work can be simplified.
[0044]
  In addition, the thickness of the second silicon oxide layer 107 that can reduce the reflectance difference with respect to the incident light of the light receiving element to 5% or less between the case where the transparent resin is coated and the case where the transparent resin is coated is 56 nm to 79 nm. The range of the thickness value is larger than that of the first silicon oxide layer 105 in the embodiment and the first silicon nitride layer 106 in the third embodiment. Therefore, the light receiving element of the present embodiment can be obtained with a reflectance that can be lowered regardless of the presence or absence of the transparent resin by layer thickness control that is easier than in the second or third embodiment.
[0045]
  (Fifth embodiment)
  Since the light receiving element of the fifth embodiment of the present invention also has the same structure as the light receiving element of the first embodiment, description will be made with reference to FIG. In the present embodiment, when the transparent resin is coated on the antireflection film 109 of the light receiving element and when the transparent resin is not coated, among the four layers constituting the antireflection film 109 included in the light receiving element, The thickness of the second silicon nitride layer 108 was changed from 3 · λ / (20 · n4) nm to 7 · λ / (20 · n4) nm. Changes in the reflectance of the antireflection film 109 and the transparent resin and the change in the reflectance of the antireflection film 109 when the thickness of the second silicon nitride layer 108 was changed were measured. The thickness of the layers other than the second silicon nitride layer 108 constituting the antireflection film 109 is λ / (17 · n1) nm for the first silicon oxide layer 105 and λ / (6 for the first silicon nitride layer 106. N2) nm and the second silicon oxide layer 107 is λ / (4 · n3) nm. Here, λ is the wavelength of incident light, n1 is the refractive index of the first silicon oxide layer 105, n2 is the refractive index of the first silicon nitride layer 106, and n3 is the refractive index of the second silicon oxide layer 107. N4 is the refractive index of the second silicon nitride layer 108. The transparent resin was an epoxy resin, the refractive index was 1.55, and was formed on the antireflection film 109 to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%.
[0046]
  FIG. 5 is a diagram showing measurement results of the reflectance of the antireflection film 109 and the transparent resin and the reflectance of the antireflection film 109 when the thickness of the second silicon nitride layer 108 is changed. In FIG. 5, the horizontal axis represents the thickness of the second silicon nitride layer 108, and the vertical axis represents the reflectance of the antireflection film 109 and the transparent resin, and the reflectance of the antireflection film 109. As can be seen from FIG. 5, in the light receiving element of this embodiment, the thickness of the second silicon nitride layer 108 is 5 · λ / (28 · n4) nm or more and 4 · λ / (13 · n4) nm or less. Thus, it can be seen that the difference in reflectance with respect to incident light can be reduced to 5% or less depending on whether or not the transparent resin is coated. In particular, in the light receiving element of the present embodiment, when the thickness of the first silicon nitride layer 106 is λ / (4 · n4) nm, the difference in reflectance with respect to incident light between when the transparent resin is coated and when not coated. Can be minimized. When the thickness of the second silicon nitride layer 108 is 5 · λ / (28 · n4) nm or more and 4 · λ / (13 · n4) nm or less, the transparent resin is coated or not. It can also be seen that the reflectivity for incident light can be reduced to 15% or less.
[0047]
  Specifically, when the wavelength of incident light is 405 nm, the refractive index of the first and second silicon oxide layers is 1.47, and the refractive index of the first and second silicon nitride layers is 2.07. If the thickness of the first silicon oxide layer 105 is 16 nm, the thickness of the first silicon nitride layer 106 is 33 nm, and the thickness of the second silicon oxide layer 107 is 69 nm, the second silicon nitride layer 108 By setting the thickness to 35 nm to 60 nm, the difference in reflectance with respect to incident light of the light receiving element can be reduced to 5% or less depending on whether or not the transparent resin is coated.
[0048]
  According to the light receiving element of the present embodiment, there is no need to change the circuit configuration of the signal processing circuit for processing the signal from the light receiving element between when the transparent resin is coated and when the transparent resin is not coated. Therefore, the manufacturing cost of the signal processing circuit can be reduced. In the product performance test, the light receiving element measures the reflectance of the antireflection film 109 in a state where the transparent resin is not coated, so that the antireflection film 109 and the transparent resin after coating the transparent resin Can be predicted almost accurately. Therefore, the performance test work can be simplified.
[0049]
  In addition, the thickness of the second silicon nitride layer 108 that can reduce the reflectance difference with respect to the incident light of the light receiving element to 5% or less between the case where the transparent resin is coated and the case where the second resin is coated is 35 nm to 60 nm. The range of the thickness value is larger than that of the first silicon oxide layer 105 in the embodiment and the first silicon nitride layer 106 in the third embodiment. Therefore, the light receiving element of the present embodiment can be obtained with a reflectance that can be lowered regardless of the presence or absence of the transparent resin by layer thickness control that is easier than in the second or third embodiment.
[0050]
  (Sixth embodiment)
  The light receiving element of the sixth embodiment of the present invention also has the same structure as the light receiving element of the first embodiment, and will be described with reference to FIG. In the light receiving element of the present embodiment, the four layers constituting the antireflection film 109 included in the light receiving element are each changed to a size within a predetermined range. Here, a change in the reflectance of the antireflection film 109 and the transparent resin and a change in the reflectance of the antireflection film 109 are measured when the transparent resin is coated on the antireflection film 109 and when the transparent resin is not coated. It was measured. That is, for each layer constituting the antireflection film 109, the thickness of the first silicon oxide layer 105 is changed between λ / (25 · n1) nm and λ / (11 · n1) nm to reduce the first silicon nitride. The thickness of the layer 106 is changed between λ / (7 · n2) nm and λ / (5 · n2) nm, and the thickness of the second silicon oxide layer 107 is changed from 19 · λ / (93 · n3) nm to 2 The thickness of the second silicon nitride layer 108 is changed between 5 · λ / (28 · n4) nm and 4 · λ / (13 · n4) nm or less by changing between λ / (7 · n3) nm and below. Changed.
[0051]
  Specifically, for incident light having a wavelength of 405 nm, the refractive index of the first and second silicon oxide layers is 1.47, and the refractive index of the first and second silicon nitride layers is 2.07. In this case, the thickness of the first silicon oxide layer 105 is 11 nm to 25 nm, the thickness of the first silicon nitride layer 106 is 28 nm to 39 nm, the thickness of the second silicon oxide layer 107 is 56 nm to 79 nm, and the second silicon nitride layer. The thickness of 108 was 35 nm or more and 60 nm or less. The transparent resin was an epoxy resin, the refractive index was 1.55, and was formed on the antireflection film 109 to a thickness of 0.5 mm. Further, an antireflection coating was applied to the resin surface so that the reflectance of the resin surface was 0%.
[0052]
  In the light receiving element of this embodiment, when the thickness of the four layers constituting the antireflection film 109 is changed, the difference in reflectance with respect to incident light is 5% or less depending on whether the transparent resin is coated or not. In order to achieve this, it has been found that it is necessary to set the film thickness within at least the above range. Further, it has been found that in order to make the reflectance of the antireflection film 109, the transparent resin, and the antireflection film 109 15% or less, it is necessary to set the film thickness to at least the above range. Therefore, according to the light receiving element of this embodiment, it is necessary to change the circuit configuration of the signal processing circuit for processing the signal from the light receiving element depending on whether or not the transparent resin is coated as in the prior art. Therefore, the manufacturing cost of the signal processing circuit can be reduced. In the product performance test, the light receiving element measures the reflectance of the antireflection film 109 in a state where the transparent resin is not coated, so that the antireflection film 109 and the transparent resin after coating the transparent resin Can be predicted almost accurately. Therefore, the performance test work can be simplified.
[0053]
  In the above embodiment, the incident light of the light receiving element may have other wavelengths. The first and second silicon oxide layers and the first and second silicon nitride layers may have other refractive indexes.
[0054]
  The transparent resin may have other refractive index and thickness.
[0055]
  (Seventh embodiment)
  FIG. 6 is a diagram showing an optical pickup section provided in the optical disc apparatus according to the seventh embodiment of the present invention, and this optical pickup section includes a light receiving element according to the present invention. This optical pickup unit divides the light emitted from the semiconductor laser 600 into three beams of two tracking sub-beams and one signal readout main beam by a tracking beam generating diffraction grating 601. Yes. These lights are transmitted through the hologram element 602 as zero-order light, converted into parallel light by the collimator lens 603, and then condensed on the disk 605 by the objective lens 604. The light collected on the disk 605 is reflected after the light intensity is modulated by the pits formed on the disk 605. The reflected light is transmitted through the objective lens and the collimator lens, and is diffracted by the hologram element 602. The primary light from the hologram element 602 is received by five light receiving elements D1 to D5 formed on the split light receiving element 606. Light is received by the surface. Outputs corresponding to the five light receiving surfaces are added and subtracted by a signal processing circuit (not shown) to obtain a data signal recorded on the disk 605 and a tracking signal of the optical pickup unit.
[0056]
  The split type light receiving element 606 is provided with an antireflection film similar to that of the light receiving element of the first embodiment on the light receiving surfaces D1 to D5. Therefore, the split-type light receiving element 606 has almost the same reflectivity with respect to incident light when the transparent resin is coated on the antireflection film and when it is not coated. As a result, the optical pickup section does not need to change the configuration of the signal processing circuit in accordance with the presence or absence of the transparent resin coating on the light receiving element 606, and thus the manufacturing cost can be reduced.
[0057]
  In the above embodiment, the optical system of the optical pickup unit may have other configurations.
[0058]
【The invention's effect】
  As is clear from the above, according to the light receiving element of the present invention.,lightIn the light receiving element having the antireflection film in the region where the light enters, the antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon, which are sequentially stacked on the semiconductor layer. It is made of a nitride layer, the wavelength of incident light is λ nm, and the refractive index of the first silicon oxide layer is n1.The refractive index of the first silicon nitride layer is n2, the refractive index of the second silicon oxide layer is n3, and the refractive index of the second silicon nitride layer is n4.The thickness of the first silicon oxide layer is λ / (25 · n1) nm or more and λ / (11 · n1) nm or less.Thus, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, the thickness of the second silicon oxide layer is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer is Is λ / (4 · n4) nmTherefore, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. Further, the reflectance of the antireflection film can be made 15% or less.
[0059]
  According to the light receiving element of the present invention, in the light receiving element having the antireflection film in the light incident region, the antireflection film is formed by sequentially stacking the first silicon oxide layer and the first silicon nitride layer on the semiconductor layer. And a second silicon oxide layer and a second silicon nitride layer, the wavelength of incident light is λ nm, and the refractive index of the first silicon nitride layer is n2.The refractive index of the first silicon oxide layer is n1, the refractive index of the second silicon oxide layer is n3, and the refractive index of the second silicon nitride layer is n4.The thickness of the first silicon nitride layer is not less than λ / (7 · n2) nm and not more than λ / (5 · n2) nm.Thus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the second silicon oxide layer is λ / (4 · n3) nm, and the thickness of the second silicon nitride layer. Is λ / (4 · n4) nmTherefore, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. Further, the reflectance of the antireflection film can be made 15% or less.
[0060]
  According to the light receiving element of the present invention, in the light receiving element having the antireflection film in the light incident region, the wavelength of the incident light is λ nm, and the refractive index of the second silicon oxide layer is n3.The refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon nitride layer is n4.The thickness of the second silicon oxide layer is 19λ / (93 · n3) nm or more and 2λ / (7 · n3) nm or less.Thus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon nitride layer is Is λ / (4 · n4) nmTherefore, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. Further, the reflectance of the antireflection film can be made 15% or less.
[0061]
  According to the light receiving element of the present invention, in the light receiving element having the antireflection film in the light incident region, the antireflection film is formed by sequentially stacking the first silicon oxide layer and the first silicon nitride layer on the semiconductor layer. The second silicon oxide layer and the second silicon nitride layer, the wavelength of incident light is λ nm, and the refractive index of the second silicon nitride layer is n4The refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3.The thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more.4λ / (13・ N4) nm or lessThus, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon oxide layer. Is λ / (4 · n3) nmTherefore, the difference in reflectance of incident light to the light receiving element can be easily reduced to 5% or less between the case where the resin is disposed on the antireflection film and the case where the resin is not disposed. Further, the reflectance of the antireflection film can be made 15% or less.
[0062]
  According to the light receiving element of the present invention, in the light receiving element having the antireflection film in the light incident region, the antireflection film is formed by sequentially stacking the first silicon oxide layer and the first silicon nitride layer on the semiconductor layer. And a second silicon oxide layer and a second silicon nitride layer, the wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, and the refractive index of the first silicon nitride layer is n2. The refractive index of the second silicon oxide layer is n3, and the second2Assuming that the refractive index of the silicon nitride layer is n4, the thickness of the first silicon oxide layer is λ / (25 · n1) nm or more and λ / (11 · n1) nm or less, and the thickness of the first silicon nitride layer is Is λ / (7 · n2) nm or more and λ / (5 · n2) nm or less, and the thickness of the second silicon oxide layer is 19λ / (93 · n3) nm or more and 2λ / (7 · n3) nm or less. Yes, the thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more4λ / (13Since n4) nm or less, the film thickness can reduce the difference in reflectance of incident light to the light receiving element to 5% or less between the case where the resin is placed on at least the antireflection film and the case where the resin is not placed. A combination of Moreover, the combination of the film thickness which can make reflectance 15% or less is included.
[0063]
  According to the light receiving element of the present invention, in the light receiving element having the antireflection film in the light incident region, the antireflection film is formed by sequentially stacking the first silicon oxide layer and the first silicon nitride layer on the semiconductor layer. And a second silicon oxide layer and a second silicon nitride layer, the wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, and the refractive index of the first silicon nitride layer is n2. The refractive index of the second silicon oxide layer is n3, and the second2Assuming that the refractive index of the silicon nitride layer is n4, the thickness of the first silicon oxide layer is λ / (17 · n1) nm, and the thickness of the first silicon nitride layer is λ / (6 · n2) nm. And the thickness of the second silicon oxide layer is λ / (4 · n3) nm,2Since the thickness of the silicon nitride layer is λ / (4 · n4) nm, the difference in reflectance of incident light to the light receiving element between the case where the resin is arranged on the antireflection film and the case where the resin is not arranged. Can be reliably reduced to 5% or less. Further, the reflectance can be reduced to 15% or less..
[0064]
  BookInvention lightPickup partAccording to the above light receiving elementChildThe same signal processing circuit is used for the light regardless of whether or not the resin is disposed on the antireflection film included in the light receiving element.Pickup partCan be configured at low costPickup partCan be formed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a light receiving element according to a first embodiment of the present invention.
FIG. 2 shows a case where the thickness of the first silicon oxide layer 105 of the antireflection film 109 is changed between the case where the resin is arranged on the antireflection film 109 and the case where the resin is not arranged in the light receiving element of the second embodiment. It is the figure which showed the change of the reflectance with respect to incident light.
3 shows a case where the thickness of the first silicon nitride layer 106 of the antireflection film 109 is changed between the case where the resin is arranged on the antireflection film 109 and the case where the resin is not arranged in the light receiving element of the third embodiment. It is the figure which showed the change of the reflectance with respect to incident light.
4 shows a case where the thickness of the second silicon oxide layer 107 of the antireflection film 109 is changed between the case where the resin is arranged on the antireflection film 109 and the case where the resin is not arranged in the light receiving element of the fourth embodiment. It is the figure which showed the change of the reflectance with respect to incident light.
5 shows a case where the thickness of the second silicon nitride layer 108 of the antireflection film 109 is changed between the case where the resin is arranged on the antireflection film 109 and the case where the resin is not arranged in the light receiving element of the fifth embodiment. It is the figure which showed the change of the reflectance with respect to incident light.
FIG. 6 is a diagram illustrating an optical pickup unit included in an optical disc device according to a seventh embodiment.
FIG. 7 is a cross-sectional view showing a conventional light receiving element.
[Explanation of symbols]
  100 silicon substrate
  101 P-type diffusion layer
  102 P-type semiconductor layer
  103 N-type diffusion layer
  104 P-type diffusion layer
  105 First silicon oxide layer
  106 First silicon nitride layer
  107 Second silicon oxide layer
  108 Second silicon nitride layer
  109 Anti-reflective coating

Claims (7)

In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
A wavelength of the incident light is [lambda] nm, the refractive index of the first silicon oxide layer is Ri der n1, the refractive index of the first silicon nitride layer is n2, the refractive index of the second silicon oxide layer is n3 , and the refractive index of the second silicon nitride layer is n4 der Rutoshite,
The thickness of the first silicon oxide layer is λ / (25 · n1) nm or λ / (11 · n1) nm Ri der less, the thickness of the first silicon nitride layer is located at λ / (6 · n2) nm , the thickness of the second silicon oxide layer is λ / (4 · n3) nm , light-receiving element the thickness of the second silicon nitride layer and said λ / (4 · n4) nm der Rukoto. In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
A wavelength of the incident light is [lambda] nm, the refractive index of the first silicon nitride layer is Ri der n2, the refractive index of the first silicon oxide layer is n1, the refractive index of the second silicon oxide layer is n3 , and the refractive index of the second silicon nitride layer is n4 der Rutoshite,
Said first silicon nitride layer thickness of λ / (7 · n2) nm or λ / (5 · n2) nm Ri der less, the thickness of the first silicon oxide layer is located at λ / (17 · n1) nm , the thickness of the second silicon oxide layer is λ / (4 · n3) nm , light-receiving element the thickness of the second silicon nitride layer and said λ / (4 · n4) nm der Rukoto. In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
A wavelength of the incident light is [lambda] nm, refractive index of the second silicon oxide layer is Ri der n3, refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2 , and the refractive index of the second silicon nitride layer is n4 der Rutoshite,
The thickness of the second silicon oxide layer is Ri 19λ / (93 · n3) nm or 2λ / (7 · n3) nm der less, the thickness of the first silicon oxide layer is located at λ / (17 · n1) nm , the thickness of the first silicon nitride layer is λ / (6 · n2) nm , light-receiving element the thickness of the second silicon nitride layer and said λ / (4 · n4) nm der Rukoto. In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
A wavelength of the incident light is [lambda] nm, the refractive index of the second silicon nitride layer is Ri der n4, the refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2 , and the refractive index of the second silicon oxide layer is n3 der Rutoshite,
The thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more 4 λ / (13 · n4) nm Ri der below, in the thickness of the first silicon oxide layer is λ / (17 · n1) nm There, the thickness of the first silicon nitride layer is λ / (6 · n2) nm , light-receiving element the thickness of the second silicon oxide layer and said λ / (4 · n3) nm der Rukoto. In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
The wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3. And the refractive index of the second silicon nitride layer is n4,
The thickness of the first silicon oxide layer is λ / (25 · n1) nm or more and λ / (11 · n1) nm or less,
The thickness of the first silicon nitride layer is λ / (7 · n2) nm or more and λ / (5 · n2) nm or less,
The thickness of the second silicon oxide layer is 19λ / (93 · n3) nm or more and 2λ / (7 · n3) nm or less,
The light receiving element, wherein the thickness of the second silicon nitride layer is 5λ / (28 · n4) nm or more and 4 λ / ( 13 · n4) nm or less. In a light receiving element having an antireflection film in a region where light enters,
The antireflection film includes a first silicon oxide layer, a first silicon nitride layer, a second silicon oxide layer, and a second silicon nitride layer sequentially stacked on the semiconductor layer,
The wavelength of incident light is λ nm, the refractive index of the first silicon oxide layer is n1, the refractive index of the first silicon nitride layer is n2, and the refractive index of the second silicon oxide layer is n3. And the refractive index of the second silicon nitride layer is n4,
The thickness of the first silicon oxide layer is λ / (17 · n1) nm, the thickness of the first silicon nitride layer is λ / (6 · n2) nm, and the thickness of the second silicon oxide layer is λ. / (4 · n3) nm, and the thickness of the second silicon nitride layer is λ / (4 · n4) nm. The optical pickup unit having a light-receiving element according to any one of claims 1 to 6.

Images