JPH0779163B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device suitable for increasing the density of charge transfer elements and a manufacturing method thereof.

2. Description of the Related Art In recent years, the demand for home video cameras has increased remarkably, and the demand for solid-state imaging devices has increased. Along with this, there is an increasing demand for higher resolution that can be realized at a low price. Therefore, there is a need for a low-cost semiconductor device (charge transfer element) that is suitable for high density and is used for a solid-state image sensor.

A typical charge transfer device is a charge transfer device.
There is a Coupled Device (hereinafter CCD). Among them, there is a trench CCD in which a transfer channel is formed in a concave shape as a device for high density (Japanese Patent Application No. 61-156630). In addition, there is a single-phase drive CCD as a simple structure of the transfer gate electrode (Jaroslav Hynecek: "Virtual Phase Technorog"
y: A New apprpoch to Fabrication of Large Area CCD '
s "), I EEE Transitions on electoron d
evices, VOL.ED-28, NO.5, p.483 May 1981)).

The conventional trench CCD and single-phase drive CCD will be described below. First, a conventional trench CCD will be described with reference to the drawings.

FIG. 4 (a) shows a schematic view of a conventional trench CCD. In FIG. 4, 401 is a p-type semiconductor, 402 is an n ⁻ region forming a charge transfer channel, 403 is an insulating film, 404 is a first transfer gate electrode, and 405 is a second transfer gate electrode. FIG. 4B shows a TT 'sectional structure along the trench groove. In FIG. 4 (b), AA ', BB', C-
A cross section perpendicular to the trench groove at C ′ is shown in FIG.
Shown in (d) and (e).

Regarding the conventional trench CCD configured as described above,
The operation will be described.

By applying a transfer pulse to the first transfer gate electrode 404 and the second transfer gate electrode 405, a signal charge is generated in the n ⁻ region 402 along the trench groove in the direction from T to T ′ (or T ′ to T). Is transferred.

Next, a single-phase drive CCD will be described with reference to the drawings.

FIG. 5A shows a cross-sectional view of the conventional single-phase drive CCD in the charge transfer direction. 501 is p-type semiconductor, 502 is n ₁ region, 503 is n ₂
A region, 504 is an n ₃ region, 505 is an n ₄ region, 506 is ap ⁺ region, 507 is an insulating film, and 508 is a transfer gate electrode. Note that n ₁ region 502
The n ₂ region 503, the n ₃ region 504, and the n ₄ region 505 are depleted in the main operation state.

The operation of the single-phase drive CCD configured as described above will be described below (the applied voltages to the transfer gate electrodes are V ₁ and V ₂ , where V ₁ <V ₂ ).

FIG. 5B is a potential diagram seen along the transfer direction of the transfer channel. As shown in FIG. 5B, first, when V ₁ is applied to the transfer gate electrode 508, the potential well becomes deeper in the order of D>C>B> A due to the difference in impurity concentration, and the signal charge is applied to the D portion. Is accumulated. V _{2 on} transfer gate electrode 508
, There is a p ⁺ region 506, so the potentials of C and D do not change and the wells of the potentials of A and B become deeper.
The signal charges are transferred from D to B by becoming deeper in the order of>D> C. When V ₁ is again applied to the transfer gate electrode 508, the signal charge is transferred from B to D this time. By repeating this, the signal charges are transferred in the direction from T to T '.

Problems to be Solved by the Invention In a trench CCD, when the trench groove is deep,
Since the manufacturing process for forming a complicated transfer gate electrode as shown in FIG. 4 becomes difficult, there is a drawback that the yield of products is low.

Further, in the single-phase drive CCD, since a part of the transfer channel is driven by fixing it to an intermediate potential, the potential well for accumulating the signal charges becomes shallow, so that the maximum amount of signal charge that can be transferred is larger than that in the multi-phase drive CCD. It had the drawback of a small dynamic range, about one-half to one-quarter.

The present invention solves the above-mentioned conventional problems by forming a trench.
An object of the present invention is to provide a semiconductor device having a large dynamic range and easy to manufacture, and a manufacturing method thereof, which have respective advantages by hybridizing a CCD and a single-phase drive CCD.

Means for Solving the Problems The semiconductor device of the present invention has a first semiconductor region of a first conductivity type, and a concave shape long in the first direction formed in the first semiconductor region of the first conductivity type. A trench groove, a second conductivity type first semiconductor region formed on a side surface and a bottom surface of the trench groove, and a direction perpendicular to the first direction inside the second conductivity type first semiconductor region. A second conductive type second semiconductor region formed along the trench groove, and a first conductive type second semiconductor region of the second conductive type second semiconductor region formed on the first direction side. A second semiconductor region and a second conductivity formed inside the first semiconductor region of the second conductivity type in contact with the second semiconductor region of the first conductivity type and in a direction perpendicular to the first direction. The third and fourth semiconductor regions of the mold, the insulating film formed on the semiconductor surface, and the insulating film separated from each other. The transfer gate formed continuously with the trench groove has an electrode.

Function With this configuration, the effective CCD transfer channel width is increased by the trench groove while the CCD occupation area on the device surface remains small, and only a single transfer gate electrode is required.
High performance and high integration of can be easily realized.

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

FIG. 1A is a sectional view of the semiconductor device in the first embodiment of the present invention in the charge transfer direction. Figure 1 (c) (d)
(E) and (f) are sectional views perpendicular to the transfer direction at A, B, C, and D in FIG. 1 (a), respectively. In FIG. 1, 101
Is a p-type semiconductor, 102 is an n ₁ region, 103 is an n ₂ region, 104 is an n ₃ region, 105 is an n ₄ region, 106 is ap ⁺ region, 107 is an insulating film, and 108 is a transfer gate electrode. Note that n ₁ region 102, n ₂ region 103, and n ₃ region
The region 104 and the n ₄ region 105 are in a depleted state in the main operating state.

The operation of the semiconductor device configured as described above will be described below. (The voltage applied to the transfer gate electrode is V
₁ and V ₂ . However, V ₁ <V ₂ ) FIG. 1B is a potential diagram seen along the transfer direction of the transfer channel. As shown in FIG. 1B, first, when V ₁ is applied to the transfer gate electrode 108, the potential well becomes deeper in the order of A, B, C, and D due to the difference in impurity concentration, and the signal charge is applied to the D portion. Is accumulated. V _{2 on} transfer gate electrode 108
Since there is added the p ⁺ region 106 of the potential of the C and D are a potential well A and B does not change becomes deep, a potential well is C,
The signal charges are transferred from D to B by becoming deeper in the order of D, A, and B. When V ₁ is again applied to the transfer gate electrode 108, the signal charge is transferred from B to D this time. By repeating this, the signal charge is transferred in the direction from T to T ′.

As described above, according to the present embodiment, the p-type semiconductor 101 (first semiconductor region of the first conductivity type) and the trench groove formed in the p-type semiconductor 101 and having a long concave shape in the first direction are formed. The n ₁ region 102 formed on the side surface and the bottom surface of the trench groove
(First semiconductor region of second conductivity type), and the n ₁ region 102
An n ₂ region 103 (second semiconductor region of second conductivity type) formed along the trench groove in a direction perpendicular to the first direction, and the n ₂ region 103 in the first direction P ⁺ region 106 formed on the side of (the second semiconductor region of the first conductivity type)
And n ₃ region 104 (second conductivity type third semiconductor region) formed in the n ₁ region 102 in contact with the p ⁺ region 106 in a direction perpendicular to the first direction, and n ₄ A region 105 (second conductivity type fourth semiconductor region), an insulating film 107 (insulating film) formed on the semiconductor surface, and a transfer gate continuously formed in the trench groove with the insulating film 107 interposed therebetween. By providing the electrode 108 (transfer gate electrode), the dynamic range can be increased with high yield.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 (a) is a layout diagram in the second embodiment. 2 (b), (c), (d),
(E) and (f) are respectively AA 'and B of FIG. 2 (a).
It is sectional drawing in -B ', CC', DD ', and TT'.

In FIG. 2, 201 is a p-type semiconductor, 202 is an n ₁ region, 203
Is the n ₂ region, 204 is the n ₃ region, 205 is the n ₄ region, 206 is the p ⁺ region, 2
Reference numeral 07 is an insulating film, 208 is a transfer gate electrode, and the above is the same as the configuration of FIG. The difference from the configuration of FIG. 1 is that
The point is that the n ⁻ region of the photodiode 209 and the p ⁻ region 210 of the read channel are provided, and the transfer gate electrode 208 also serves as the read gate electrode. Note that n ₁ region 102 and n ₂ region 1
The 03, n ₃ region 104, and n ₄ region 105 are depleted in the main operating state.

The operation of the semiconductor device configured as described above will be described below.

The electrons generated by the incident light are the n ^- region of the photodiode.
Accumulate in 209. When a high voltage V _H (where V _H >> V ₂ > V ₁ ) is applied to the read gate electrode 208, a signal is transferred from the n ⁻ region 209 of the photodiode to the transfer channel n ₁ region 202 of the single-phase trench CCD. The charge is read out. By applying the transfer pulses V ₁ and V ₂ to the transfer gate electrode 208, the signal charges are transferred in the same manner as in the first embodiment.

As described above, according to the present embodiment, the p-type semiconductor 201 (first conductivity type first semiconductor region) and the trench groove formed in the p-type semiconductor 201 and having a long concave shape in the first direction are formed. The n ₁ region 202 formed on the side surface and the bottom surface of the trench groove
(First semiconductor region of second conductivity type), and the n ₁ region 202
And n ₂ region 203 formed along the trench in the direction perpendicular to the first direction within the (second semiconductor region of a second conductivity type), the first direction of the n ₂ region 203 P ⁺ region 206 formed on the side of (the second semiconductor region of the first conductivity type)
An n ₃ region 204 (second conductivity type third semiconductor region) and an n ₄ region 205 (which are formed in the n ₁ region in contact with the p ⁺ region in a direction perpendicular to the first direction). Second conductivity type fourth semiconductor region) and n ⁻ region 209 (second conductivity type photoelectric conversion region) of the photodiode formed on the p-type semiconductor 201.
And an insulating film 207 (insulating film) formed on the semiconductor surface and having the p ⁻ region 210 (third semiconductor region of the first conductivity type) of the read channel and the insulating film 207. By providing the transfer gate electrode 208 (transfer gate electrode) formed continuously in the trench groove so that the transfer gate electrode 208 also serves as the read gate electrode, a solid-state imaging device having a high yield and a large dynamic range can be obtained. can do.

Note that the conductivity types of the semiconductors may be reversed in both the first embodiment and the second embodiment.

Next, a semiconductor device manufacturing method of the present invention will be described with reference to the drawings.

In the following, the same numbers as in the embodiment of FIG. 1 are used. 3 (a), (b), (c), (d), (e), (f), (g), and (h), the left diagram is a sectional view in the transfer direction, and the right diagram is a sectional view perpendicular to the transfer direction.

(1) As shown in FIG. 3 (a), boron 10 ^14-10
P-type silicon substrate with a resistivity of 10 cm ^-1 to 10 ² Ω · cm including ¹⁶ cm ^-3 1
A part of 01 is plasma-etched to form a trench groove having a long concave shape in the first direction.

(2) As shown in FIG. 3 (b), rotary ion implantation of phosphorus (dose amount N = 1 × 10 6) is performed on the side surface and the bottom surface of the trench groove.
¹¹ to 10 ¹³ cm ^-2 , implantation energy E = 50 to 200 keV)
An n ₁ region 102 is formed.

(3) As shown in FIG. 3C, phosphorus is ion-implanted into the n ₁ region 102 by rotational ion implantation (dose amount N = 1.2 × 10 ¹¹ -10).
¹³ cm ^-2 , implantation energy -E = 50 to 150 keV) and n ₂ region along the trench groove in a direction perpendicular to the first direction.
Form 103.

(4) As shown in FIG. 3D, phosphorus is rotationally ion-implanted into the n ₁ region 102 (dose amount N = 1.4 × 10 ¹¹ to 10 10).
¹³ cm ^-2 , implantation energy E = 50 to 200 keV) and n ₃ region along the trench groove in a direction perpendicular to the first direction.
Form 104.

(5) As shown in FIG. 3 (e), rotational ion implantation of phosphorus into the n ₁ region 102 (dose amount N = 1.6 to 10 ¹¹ to 10)
¹³ cm ^-2 , implantation energy E = 50 to 200 keV) and n ₄ region along the trench groove in a direction perpendicular to the first direction.
Form 105.

(6) As shown in FIG. 3 (f), rotary ion implantation of boron (dose amount N =) is performed on the surfaces of the n ₃ region 103 and the n ₄ region 104.
1.0 × 10 ¹¹ to 10 ¹³ cm ^-2 , implantation energy E = 50 to 150
keV) to form the p ⁺ region 106.

(7) As shown in FIG. 3 (g), once the oxide film on the semiconductor surface is removed, a three-layer structure (SiO ₂ / SiN) is formed on the semiconductor surface.
An insulating film 107 having a thickness of / SiO ₂ of 1 to ₂ μm is formed.

(8) As shown in FIG. 3H, transfer gate electrode 1 is formed by depositing polysilicon in the trench with an insulating film 107 interposed therebetween.
Forming 08.

As described above, according to this embodiment, the charge transfer channel capable of single-phase driving can be formed in the trench groove.

In the manufacturing method, solid phase diffusion may be used instead of rotary ion implantation.

EFFECTS OF THE INVENTION As described above, according to the present invention, a single-phase drive type trench CCD has a large dynamic range characteristic and an easy manufacturing method, and can achieve high performance and high integration.

[Brief description of drawings]

1A is a sectional view of the semiconductor device (CCD) in the charge transfer direction in the first embodiment of the present invention, and FIG. 1B is a charge transfer of the semiconductor device in the first embodiment of the present invention. Direction potential diagram, FIG. 1 (c), (d), (e),
2F is a cross-sectional view perpendicular to the charge transfer direction, FIG. 2A is a layout diagram of a semiconductor device (solid-state image pickup device) according to the second embodiment of the present invention, and FIGS. 2B and 2C. , (D),
(E) and (f) are cross-sectional views of the semiconductor device according to the second embodiment of the present invention, and FIGS. 3 (a), (b), (c),
(D), (e), (f), (g) and (h) are manufacturing process diagrams of the semiconductor device in the first embodiment of the present invention, and FIG. 4 (a) is a conventional trench CCD. Overview, Fig. 4 (b)
Is a sectional view of the conventional trench CCD in the transfer direction, FIGS. 4 (c), (d), and (e) are sectional views perpendicular to the charge transfer direction of the conventional trench CCD, and FIG. 5 (a) is FIG. 5B is a potential diagram of the conventional single-phase driving CCD, and FIG. 5B is a potential diagram of the conventional single-phase driving CCD. 101 …… p-type semiconductor, 102 …… n ₁ area, 103 …… n ₂ area, 1
04 …… n ₃ areas, 105 …… n ₄ areas, 106 …… p ⁺ areas, 107…
... insulating film, 108 ...... transfer gate electrode, 201 ...... p-type semiconductor, 202 ...... n ₁ regions, 203 ...... n ₂ regions, 204 ...... n ₃ regions, 2
05 …… n ₄ area, 206 …… p ⁺ area, 207 …… insulating film, 208…
... transfer gate electrode, 209 ...... photodiode n ^- region 210 ...... read channel p ^- region, 401 ...... p-type semiconductor, constituting 402 ...... charge transfer channel n ^- region, 403
...... Insulating film, 404 ...... First transfer gate electrode, 405 ...... Second transfer gate electrode, 501 ...... P type semiconductor, 502 ...... n ₁ area, 503 ...... n ₂ area, 504 ...... n ₃ areas, 505 …… n ₄ areas, 5
06 …… p ⁺ region, 507 …… insulating film, 508 …… transfer gate electrode.

Claims (4)

[Claims] 1. A first semiconductor region of a first conductivity type, a trench groove formed in the first semiconductor region of the first conductivity type and having a long recess in a first direction, and a side surface of the trench groove. And a second semiconductor region of the first conductivity type formed on the bottom surface, and formed inside the first semiconductor region of the second conductivity type along the trench groove in a direction perpendicular to the first direction. A second semiconductor region of the second conductivity type, a second semiconductor region of the first conductivity type formed on the side of the second direction of the second semiconductor region of the second conductivity type, Second conductivity type third and fourth semiconductors formed inside the first conductivity type second semiconductor region in contact with the first conductivity type second semiconductor region in a direction perpendicular to the first direction. A region, an insulating film formed on the semiconductor surface, and a transfer film continuously formed in the trench groove with the insulating film interposed therebetween. Wherein a has a gate electrode. 2. The second semiconductor region of the second conductivity type and the third semiconductor region are in contact with each other, and the third semiconductor region of the second conductivity type and the fourth semiconductor region are in contact with each other. 1. The semiconductor device according to 1. 3. A first semiconductor region of a first conductivity type, a trench groove formed in the first semiconductor region of the first conductivity type and having a concave shape elongated in a first direction, and a side surface of the trench groove. And a second semiconductor region of the first conductivity type formed on the bottom surface, and formed inside the first semiconductor region of the second conductivity type along the trench groove in a direction perpendicular to the first direction. A second semiconductor region of the second conductivity type, a second semiconductor region of the first conductivity type formed on the side of the second direction of the second semiconductor region of the second conductivity type, Second conductivity type third and fourth semiconductors formed inside the first conductivity type second semiconductor region in contact with the first conductivity type second semiconductor region in a direction perpendicular to the first direction. A region, a second-conductivity-type photoelectric conversion region formed in the first semiconductor region of the first-conductivity type, and the second-conductivity type A third semiconductor region of the first conductivity type formed between the photoelectric conversion region and the first semiconductor region of the second conductivity type, an insulating film formed on the semiconductor surface, and the insulating film separated from each other. It has a transfer gate electrode continuously formed in the trench groove, and the transfer gate electrode is formed so as to project so as to cover the third semiconductor region of the first conductivity type and also serves as a read gate electrode. Characteristic semiconductor device. 4. A first step of forming a trench groove having a long concave shape in a first direction on a semiconductor substrate of a first conductivity type, and a first conductivity type first groove on a side surface and a bottom surface of the trench groove. A second step of forming a semiconductor region, a second semiconductor region of the second conductivity type along the trench groove in a direction perpendicular to the first direction in the first semiconductor region of the second conductivity type. A third step of forming, a fourth step of forming a third semiconductor region of a second conductivity type, a fifth step of forming a fourth semiconductor region of a second conductivity type, and the second step A sixth step of forming a second semiconductor region of the first conductivity type on the surface side of the third semiconductor region of the conductivity type and the fourth semiconductor region, and a seventh step of forming an insulating film on the semiconductor surface And an eighth step of forming a transfer gate electrode in the trench groove with the insulating film interposed therebetween. Manufacturing method of the device.