JPH04340226A - Method and device for etching semiconductor substrate - Google Patents

Abstract

PURPOSE:To provide an etching method, wherein a semiconductor substrate is dipped in an etching liquid, is etched and fluctuation in a reaction rate of etching to be accompanied by heat generation is dissolved, and the device for the etching method. CONSTITUTION:A wafer 1 is brought into contact with grooves in a plurality of rotating stages 2 meshed with a transfer gear to make the wafer 1 make a self-sustaining rotation and an etching liquid is jetted on both surfaces of the wafer 1 through etching spray nozzles 6, which are swung by a dynamic arm 15 in the vertical directions of the wafer 1, and the wafer is etched. An etching of the wafer can be performed at a stable reaction rate and the flatness of the wafer of almost the same level as that of the flatness of a wafer obtainable by a lapping processing is obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method of etching semiconductor substrates such as silicon wafers, in which etching is performed by simultaneously spraying an etching solution onto both sides of a rotating wafer using a spray nozzle. The present invention relates to a method and apparatus for etching a semiconductor substrate that is not affected by heat generation when immersed in water.

0002

[Prior Art] In the manufacturing process of silicon wafers, CZ
There are steps in which a single-crystal ingot pulled by the FZ method or FZ method is processed into an external shape, cut out by slicing, chamfered, made uniform in thickness by lapping, and then removed by etching to remove the strained layer.

[0003] Generally, in the etching process, a large number of wafers are immersed in a bath containing an etching solution containing hydrofluoric acid, nitric acid, acetic acid, water, etc. in the required ratio, and the processed strained layer is chemically removed. .

In this etching, the reaction rate is determined by the etching solution composition ratio, temperature, solution stirring method, etc., and the heat generated by the silicon wafer reacting with the etching solution accelerates the reaction rate.

[0005]

[Problems to be Solved by the Invention] Nowadays, large-diameter silicon wafers are required, but as the diameter increases, heat generation during the etching process increases, and the reaction rate tends to be further accelerated. Therefore, in the method of etching a large number of wafers by immersing them in an etching solution, as the wafer diameter increases, it becomes extremely difficult to control the reaction rate and wafer shape.

[0006] The present invention provides a method and apparatus for etching a semiconductor substrate that eliminates fluctuations in reaction rate caused by heat generation in a method in which a semiconductor substrate is etched by immersing it in an etching solution, and is not adversely affected by such heat generation. The purpose is

[0007]

SUMMARY OF THE INVENTION The present invention is a method of etching a semiconductor substrate, which is characterized in that etching is performed by spraying an etching solution onto both sides of the substrate while rotating the semiconductor substrate. Further, the present invention has a substrate rotation means for rotating the semiconductor substrate while holding it independently, and a spray nozzle means for spraying the etching solution while changing the spray direction, so that the etching solution can be applied to both sides of the semiconductor substrate while rotating the semiconductor substrate. This is an etching apparatus for a semiconductor substrate, characterized in that it performs etching by spraying.

[0008]

[Operation] This invention is characterized in that etching is carried out by spraying an etching solution onto both sides of the semiconductor substrate while rotating the substrate. Since the wafer rotates, the etching solution on the wafer surface is constantly replaced, and the temperature of the etching solution on the wafer surface that is being etched does not rise, which has the advantage of not being affected by heat. The wafer can also be rotated while being held horizontally.
To prevent warpage and uniform etching on both sides, it is preferable to rotate while holding it by itself.

[0009] In the etching method of the present invention, the etching solution sprayed onto both sides of the semiconductor substrate does not stay there and is constantly replaced, so there is no rise in surface temperature, and the etching reaction rate depends on the composition, spraying time, and volume of the etching solution. ,
Since it is determined according to the injection pressure and is kept constant,
Etching can be performed at a stable reaction rate that is not affected by heat from the reaction, making it easier to control the amount of etching and the shape of the wafer.

In the present invention, the substrate rotation means for rotating the semiconductor substrate while holding it independently uses a plurality of rotary disks having grooves on the circumference, as shown in the embodiment, to rotate the semiconductor substrate in a self-supporting manner. Any configuration can be adopted as long as it is possible. The substrate rotation means constantly rotates during etching or rinsing to assist the etching solution or rinsing pure water solution to diffuse onto the substrate surface, and the speed depends on the composition of the etching solution and the spraying time. , capacity, and injection pressure, but if the rotation speed is too high, uneven etching tends to occur, so for example, 20
It is preferable to rotate at a speed of 0 to 400 rpm.

As the substrate rotates, it is possible to use a plurality of spray nozzles that spray etching solution onto both sides of a wafer that is vertically supported, with a fixed spray direction; It is preferable to use a configuration in which the ink can be sprayed while the etching is being performed in order to prevent the occurrence of uneven etching. The spray pattern of the spray nozzle is preferably conical, and the spray nozzle may be divided into a plurality of parts to improve the diffusion of the etching solution. Further, the spraying amount of the etching solution is preferably 1 l/min or more; if the spraying amount is small, the wafer surface may become dry and uneven etching may occur. The injection pressure of the etching solution was set at 1.0 kg/1.0 kg to prevent the wafer surface from drying and uneven etching.
cm2 or more, preferably 1.0 to 1.5 kg/cm2.

0012

【Example】

Example 1 An example of the present invention will be described below based on the drawings. The rotation stage 2 for self-rotating the wafer 1 shown in FIGS. 1 and 2 consists of a plurality of disks with transmission gears coaxially fixed thereon and grooves on the circumferential surface that come into contact with the edges of the wafer 1.
A transmission gear 5 is disposed between each rotation stage 2 and meshed with each other to transmit the rotational force from the rotation motor 3 via the transmission shaft 4 to each rotation stage 2, thereby maintaining contact with a plurality of rotation stages 2. The wafer 1 can be rotated independently.

An etching spray nozzle 6 and a rinsing spray nozzle 7 are installed on both sides of the wafer 1 at a required interval.
Multiple pieces are arranged facing each other. Here, the etching spray nozzle 6 has a plurality of nozzles arranged in parallel in the diameter direction of the wafer 1 as shown in FIG. Consisting of:

As shown in FIG. 3, the etching solution is supplied from an etching solution supply tank 8 to an etching spray nozzle 6 by a supply pump 9, and is sprayed onto both sides of the wafer 1. The injected etching solution is collected in a recovery tank 10, and in order to add the etching solution consumed by the reaction, the consumed amount is replenished from the concentration holding tank 12. This etching solution is recycled from the recovery tank 10 to an etching solution supply tank by a recovery pump. Also, when recovering the etching solution,
During etching, the recovery valve 13 is opened and the drain valve 14 is opened.
is closed. At the end of etching, the recovery valve 13 is closed and the drain valve 14 is opened to prevent the etching solution and rinsing pure water from being mixed.

With the etching apparatus of the present invention having the above configuration, the etching solution sprayed onto both sides of the wafer 1 diffuses over the substrate surface and is constantly replaced.
Etching can be performed at a stable reaction rate that is not affected by heat from the reaction.

Embodiment 2 In the etching apparatus configured as shown in Embodiment 1, the etching spray nozzle is oscillated at an angle within 20 degrees up and down with respect to the radial center of the wafer 1, as shown in FIG. 4A. As shown in FIG. 4B, the facing distance from the wafer 1 is set to 150 to 200 mm, and in the case of an 8-inch diameter, the etching is performed at four locations as shown in FIG. 4C. was carried out. As a result, etching can be performed at a stable reaction rate that is not affected by the heat generated by the reaction, and the wafer shape can be controlled to the same level as the lapping process, as shown in the TTV (thickness variation) in Figure 5. became.

For comparison, we performed a conventional etching method in which the wafer is immersed in an etching solution bath.
As shown in the TV, both flatness and lapping are incomparably superior to conventional immersion etching methods. The operating conditions of the etching apparatus of the present invention were as follows: wafer rotation speed was 300 rpm, etching solution spray amount was 1.2 l/min, and pressure was 1.5 kg/cm<2>.

[0018]

[Effects of the Invention] This invention performs etching by spraying an etching solution onto both sides of the semiconductor substrate while rotating the substrate, thereby achieving a stable reaction rate that is not affected by the heat generated by the reaction during etching. The wafer could be etched, and as shown in the examples, etching with good flatness was possible.

[Brief explanation of drawings]

FIG. 1 is a perspective explanatory view showing the structure of a substrate rotation means and an etching spray nozzle according to the present invention.

FIG. 2A is an explanatory diagram showing the configuration of a transmission gear of a rotary stage according to the present invention, and FIG. 2B is an explanatory diagram showing details of a groove portion.

FIG. 3 is a flow diagram of an etching apparatus according to the present invention.

FIG. 4 is an explanatory diagram showing the arrangement of the spray nozzle with respect to the wafer of the etching apparatus according to the present invention, where a is the swing angle of the spray nozzle, b is the distance between the nozzle and the wafer surface, and c is the swing trajectory of the nozzle. shows.

FIG. 5 is a graph showing TTV of a wafer.

[Explanation of symbols]

1 Wafer 2 Rotating stage 3 Rotating motor 4 Transmission shaft 5 Transmission gear 6 Spray nozzle for etching 7 Etching nozzle for rinsing 8 Etching liquid supply tank 9 Supply pump 10 Recovery tank 11 Recovery pump 12 Concentration holding liquid supply tank 13 Recovery valve 14 Drain valve 15 Swing arm 16 Spray nozzle installation jig

Claims (2)

[Claims] 1. A method of etching a semiconductor substrate, which comprises performing etching by spraying an etching solution onto both sides of the substrate while rotating the semiconductor substrate. 2. A substrate rotation means for rotating the semiconductor substrate while holding it independently, and a spray nozzle means for spraying the etching solution while changing the spray direction, and spraying the etching solution onto both sides of the substrate while rotating the semiconductor substrate. An etching device for semiconductor substrates that performs etching by spraying.