JPH01260829A - Semiconductor manufacturing equipment - Google Patents

Abstract

PURPOSE:To overcome the dependency on a pattern direction, by splaying etchants having nearly uniform direction and strength in an etching range and causing the linear velocity of rotating of a wafer to be smaller than that of spraying the etchants in every point on the wafer. CONSTITUTION:A nozzle is provided with holes 17 so that the surface density in an elliptical surface is made uniform and the size of its ellipse is determined in such a way that its long diameter (a) is longer than the diameter of a wafer and a short diameter (b) may satisfy the equation: b=a.sintheta where the angle of the nozzle is theta. Further, the shape of a side face is adjusted so that amounts of spraying from respective holes are constant and pressure losses reaching respective holes become approximately equal. When etched, the wafer 11 is held by a chuck consisting of pins 12, an arm 13, and an axis 14 and then, etchants 16 are sprayed from a nozzle 15 while the wafer is rotating. In such a case, the flow of etchants is kept almost constant in every point on the wafer and etching plate does not depend upon the direction of a pattern and further, the etchants are distributed uniformly in the wafer by making the rotating of the wafer have the linear velocity which is slower than the flowing speed of the sprayed etchants.

Description

[Detailed Description of the Invention] [Summary] Regarding semiconductor manufacturing equipment, particularly manufacturing equipment that performs wet etching in the manufacturing of semiconductor devices, wet etching is generally used where the etching rate does not depend on the direction of the pattern and the etching rate has a good distribution within the wafer. The purpose of the present invention is to provide a wet etching apparatus that etches a semiconductor substrate, a metal film on a semiconductor substrate, a semiconductor film, an insulating film, etc. using an etching solution. It has a spray port that sprays the etching solution in a uniform direction and intensity, and is designed so that the linear velocity at any point in the range is smaller than the velocity of the etching solution sprayed from the spray port. The present invention includes a semiconductor manufacturing apparatus characterized by having a mechanism for rotating a substrate.

[Industrial application field]

The present invention relates to semiconductor manufacturing equipment, and particularly to a manufacturing equipment that performs wet etching in the manufacturing of semiconductor devices.

[Conventional technology]

In recent years, the scale of semiconductor integrated circuits has been rapidly increasing, and there is a strong desire to improve the degree of construction. Therefore, it is absolutely necessary to miniaturize not only active elements such as transistors but also element isolation regions. In the case of silicon LSIs, the element isolation method conventionally used is a dielectric isolation method using 5iOz formed by selective oxidation of silicon. However, with this method, the so-called bird's beak (
bird'5beak) and the reduction in active area width due to C
There are limits to reducing the width of the isolation region, such as the problem of latch-up in well isolation of a MOS structure.

Therefore, trench isolation technology is currently being developed and has been put into practical use to some extent.

Referring to FIG. 3, in this method, a groove 32 of an appropriate depth is formed in a silicon substrate 31, and a filler made of a dielectric or a laminated film of a dielectric and a semiconductor is buried inside the groove 32 to isolate the elements. It is something to do. In the figure, 33 is a 5t02 film formed on the side wall of the trench, and 34 and 35 are 5i02B'A films used as masks when etching the trench.
and silicon nitride film. After forming such a groove, for example, polysilicon 36 is grown by, for example, chemical vapor deposition (CVD) to the position shown by the broken line, and then the polysilicon is etched in the direction of the arrow, and the etching is stopped at the point shown by the solid line to form the groove 32. Fill it with polysilicon 36. In the manufacturing process of filling the trench with a filler, etching back using wear etching is considered to be a promising method because of its good selectivity and less damage.

Among conventional wet etching equipment, the following conditions are met in the etchback process: good distribution within the wafer, good wafer-to-wafer reproducibility, and the ability to detect end points and quickly stop etching. A single-wafer spin etcher satisfies this requirement.

FIG. 4 is a block diagram of a conventional spin-effer. A semiconductor substrate 1 is held by a chuck with a pin 2, an arm 3, and a shaft 4, and etching is performed by spraying an etching liquid 6 from a spray nozzle 5 while rotating the semiconductor substrate 1 at a speed of about 80 rpm.

In this figure, the nozzle for simultaneously etching the polysilicon attached to the back surface and the optical system for detecting the end point are omitted.

A spin etcher with this configuration requires relatively high speed rotation of about 800 rpm in order to ensure uniformity of etching rate within the wafer.

[Problem to be solved by the invention]

During etching with conventional equipment, a radial flow of etching solution is created across the wafer surface. For this reason, when performing a slight overetch to eliminate any residue after etchback is complete, the etching rate within the grooves is faster than in other areas in patterns where the groove direction is approximately parallel to the radial direction. However, there was a problem in that the flatness of the substrate surface was lost after the etch-back filling process was completed.

FIG. 5 is a diagram showing etching of a wafer, and the inventor of the present invention
A resist pattern of chips 42a and 42b was formed on a wafer 41. The chip 42a was provided directly below the rotation center 41a for the sea urchin as shown in the figure, and the chip 42b was provided to the left of the rotation center. Pattern 43 is the same groove pattern as groove 32 in FIG. 3, and 44 is a cylindrical hole (circular pattern) with the same depth as the groove formed for the experiment, and polysilicon 45 is formed in the groove and hole. embedded. Using such a pattern, polysilicon grown on the wafer 41 was etched at a rotation speed of 800 rpm using the spin etcher shown in FIG. The polysilicon 45 in the trench 43 is overetched so that the polysilicon 45 in the trench 43 is overetched, and in the left chip 42b, the polysilicon is etched so that the surface of the trench 43 is flush with the wafer surface, as shown in the cross-sectional view on the left side of the wafer. Ta. In addition, both chips 42a, 4
2b, polysilicon was etched in hole 44 to approximately the same height as the wafer surface. From this phenomenon, the inventor discovered that when the wafer 41 rotates at a rotational speed of 80 rpm, the etching solution is blown away by centrifugal force in the direction shown by the white arrow in figure t. It was inferred that etching would proceed quickly in the chip 42a) where the direction of the groove pattern coincided with that of the groove pattern, and that etching would proceed slowly where the direction of the groove pattern was perpendicular to the direction of the arrow (chip 42b). The fact that the polysilicon holes were etched to the same depth on both chips seems to support this reasoning.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wet etching apparatus in which the etching rate generally does not depend on the direction of the pattern and the etching rate has good distribution within the wafer.

[Means to solve the problem]

In the present invention, the sprayed etching solution is sprayed using a nozzle so that the direction is approximately parallel and uniform over the entire surface of the wafer, and the flow rate of the sprayed etching solution is also controlled at the periphery of the wafer. A configuration is adopted in which etching is performed by rotating the wafer at a speed that is slower than the current speed.

That is, when the radius of the wafer is r, the angular velocity of rotation of the wafer is ω, and the velocity of the flow of the sprayed etching liquid is (■), the wafer is rotated so as to satisfy the condition r·ω<V.

[Effect]

According to the method of the present invention, the above problems can be solved as follows.

First, the etching rate depends on the amount of etching solution supplied at each point on the wafer and the speed of the flow on the surface.
In the configuration of the present invention, the nozzle shape ensures that the supply is uniform within the wafer, and the velocity of the flow on the surface is uniform within the wafer since the flow at the time of spraying is not significantly disturbed by rotation. . Therefore, uniformity of etching rate within the wafer can be ensured.

Second, since the direction of flow on the surface is approximately the same at each instant and the wafer rotates against it, no effect of flow direction is averaged out at any point on the wafer. Therefore, there is no pattern dependence of the etch rate.

Referring to FIG. 2 showing the principle of the present invention, when the radius of the wafer 41 on which the chip 42 is formed is r, and the angular velocity is ω, the linear velocity around the chip is indicated by the arrow r and ω. Occur. When the etching solution is sprayed toward this wafer 41 at a speed of V, if r・ω>V, the phenomenon explained with reference to FIG. 5 will occur.
・When ω is set to v, even if the wafer 41 rotates in the direction of the arrow ■, the etching liquid always flows in the direction of the dashed arrow.For the 11 [1i1 chip, there are times when the flow direction of the etching liquid is parallel to the groove pattern, and at the next point in time the flow direction of the etching liquid is perpendicular to the groove pattern. In other words, the groove pattern of each chip and the flow direction of the etching solution change on average for all chips, so overall they become uniform, and the polysilicon in all grooves is etched evenly. That will happen.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 is an explanatory diagram of an embodiment of the present invention. Same figure [a]
is a front view of a nozzle, in which holes 17 are formed in an elliptical plane so that the surface density is constant.

Here, the major axis a of the ellipse is greater than or equal to the diameter d of the wafer, and the minor axis satisfies b=a·sin θ, where θ is the angle of the nozzle. Further, the side surface shape is adjusted so that the pressure loss reaching the guard hole 17 is approximately equal so that the amount of ejection from the guard hole 17 is constant.

Figure ('b) is an overall configuration diagram. While the wafer 11 is held and rotated by a chuck consisting of a pin 12, an arm 13, and a shaft 14, etching is performed by spraying an etching liquid 16 from the nozzle 15. At this time, the etching liquid 16
The flow is almost constant at any point on the wafer,
Pattern direction dependence can be eliminated by setting the rotational speed to an appropriate speed.

Note that the flow rate of the etching liquid and the wafer rotation speed must be determined experimentally based on the shape and number of holes in the nozzle. At this time, the nozzle angle θ affects the flow rate V of the etching liquid (when θ = 0 and θ = 90°, the velocity of the etching liquid on the wafer is V and 0), so the nozzle angle should also be considered. There must be.

In this embodiment, the elliptical nozzle is provided with holes of a constant density and the same size, but the density and size of the holes may be changed hydrodynamically to ensure uniformity.

Further, although the nozzle was oval in this embodiment, similar results can be obtained by using holes arranged in a straight line if the nozzle angle is appropriately selected. Further, although not shown in this embodiment, an end point detection mechanism and simultaneous etching on the back surface may be arranged in parallel.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain an etching apparatus that has a uniform etching rate within a wafer regardless of the direction of the pattern, and therefore, by using the apparatus of the present invention, highly accurate etching is possible. Semiconductor manufacturing yield and reliability are improved. Note that although the above example describes etching polysilicon, the scope of the present invention is not limited to that case, and can also be applied to etching semiconductor substrates, metal films on semiconductor substrates, semiconductor films, insulating films, etc. This also applies to cases.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, in which (a) is a front view of a nozzle, (b) is an overall configuration diagram, FIG. 2 is a diagram illustrating the present invention in detail, and FIG. 3 is a semiconductor substrate. 4 is a diagram showing the configuration of a conventional spin errature, and FIG. 5 is a diagram showing etching of a wafer. In the figure, 11 is a wafer, 12 is a pin, 13 is an arm, 14 is a shaft, 15 is a nozzle, 16 is an etching liquid, and 17 is a hole. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Moto Kuki Akira Fuyoshirone 1 Row 4 Obscene Figure 1 Fujiang Lang ^ I'm ashamed of the threat Figure 2 I'm ashamed of the threat Figure 2 Figure 5

Claims (1)

[Claims] A wet etching apparatus that etches a semiconductor substrate, a metal film on the semiconductor substrate, a semiconductor film, an insulating film, etc. using an etching solution, in a substantially uniform direction in a range that substantially coincides with the range to be etched. A spray nozzle (15
), and has a mechanism for rotating the semiconductor substrate so that the linear velocity at any point within the range is smaller than the velocity of the etching solution (16) sprayed from the spray port (15). A semiconductor manufacturing device characterized by: