TWI514933B - Apparatus of generating planarized focusing plasma for deep etching - Google Patents

Description

Plane focusing deep etching plasma generating device

This invention relates to a plasma generating apparatus, and more particularly to a planar focusing plasma generating apparatus.

Micro Electro Mechanical Systems (MEMS) is a smart, miniaturized system. Its function includes sensing, processing or actuation functions that require the integration of two or more electronic, mechanical, optical, chemical, biological, magnetic or other properties onto a single or multiple wafer. Its application fields are extremely extensive, including manufacturing, automation, information and communication, aerospace industry, transportation, civil engineering, environmental protection, agriculture, forestry, fishery and animal husbandry. Due to the system integration characteristics of MEMS, the specifications of the requirements can be described as "various". The rules of "the smaller the circuit size is better" of the integrated circuit are completely unsuitable for MEMS products.

At present, mainstream MEMS companies were established 15 years ago, and there is a need to form a high aspect ratio in the design of a type of MEMS products. The deep trenches are used to achieve the purpose of moving the structure. However, this aspect ratio is much larger than the common ditch aspect ratio (<15:1), which makes the MEMS product design always limited by the support capacity of the production machine. It was not until 2001 that there were some deep etching machines with mass production capabilities, such as the Surface Etching Machine (STS) deep etching machine. However, the products that can be stably mass-produced are still large-scale products with a depth-to-width ratio of less than 30:1, although the academic experiment can achieve a depth ratio of 100:1.

However, in view of the demand for MEMS dissimilation products, the yield and yield of various products with high aspect ratio trenches are not stable enough, so there is a need to solve this problem.

Accordingly, one aspect of the present invention is to provide a device for planarly focusing deep etch plasma comprising an etch chamber.

The etch chamber contains reaction chamber inlets, coils, funnels, and confinement rings. The reaction chamber inlet is used to input an etching gas. The coil is disposed on the outer side of the reaction chamber wall and below the inlet of the reaction chamber for causing the etching gas to generate etching plasma.

The funnel is disposed in the reaction chamber and below the coil for collectively etching the distribution range of the plasma. The diameter of the inlet of the funnel is larger than the diameter of the outlet of the funnel, and the diameter of the outlet of the funnel is 0.8-1.2 times the diameter of the wafer.

The limiting ring contact ring is disposed on the inner side wall of the funnel for pre-filtering the etching plasma to reduce the number of ions moving laterally in the etching plasma. The inner diameter of the confinement ring is 1-1.2 times the diameter of the wafer and is greater than or equal to the diameter of the outlet of the funnel.

Due to the adjustment of the above-mentioned funnel outlet and the inner diameter of the restriction ring, a planarly focused deep etching plasma can be produced. If the position of the wafer is adjusted, the etching rate can be further adjusted.

Referring to FIG. 1 , a cross-sectional structural view of an etching reaction chamber according to an embodiment of the present invention is illustrated. The etching reaction chamber can be disposed in a deep etching machine.

In FIG. 1, the etching reaction chamber 100 has an air inlet 105 for allowing an etching gas to enter the etching reaction chamber 100. A coil 110 is disposed on the outer wall below the inlet 105 of the etching reaction chamber 100 for ionizing the etching gas entering the etching reaction chamber 100, and causing the etching gas to generate the etching plasma 150 in the etching reaction chamber 100 for etching. reaction.

Within the etching reaction chamber 100 below the coil 110, a funnel 115 is disposed to limit the distribution range of the etched plasma. The diameter of the air inlet 115a above the funnel 115 is larger than the diameter D1 of the air outlet 115b below the funnel 115 to etch the plasma to a central position. Moreover, according to an embodiment, the diameter D1 of the air outlet 115b below the funnel 115 is 0.8-1.2 times the diameter of the wafer. For example, when the wafer is 6 吋 wafer, the diameter D1 of the air outlet 115b of the funnel 115 may be 140-160 mm; when the wafer is 8 吋 wafer, the diameter D1 of the air outlet 115b of the funnel 115 may be 190-205 mm.

A restriction ring 120 is disposed in the funnel 115, and the contact ring is disposed on the inner wall of the funnel 115. According to an embodiment, the inner diameter D2 of the confinement ring 120 needs to be greater than or equal to the diameter D1 of the air outlet 115b of the funnel 115, and the inner diameter D2 is 1-1.2 times the diameter of the wafer. For example, when the wafer is 6 吋 wafer, the inner diameter D2 of the limiting ring 120 is 160-180 mm; when the wafer is 8 吋 wafer, the inner diameter D2 of the limiting ring 120 is 205-225 mm. The function of the confinement ring 120, in addition to the concentrated etching of the plasma, can also filter out laterally moving ions in the etched plasma to reduce the chance of lateral etching.

A carrier 125 is disposed under the funnel 115 for carrying the wafer 130 to be etched. The position of the stage 125 can be adjusted up and down by adjusting the distance Ds between the wafer 130 and the outlet 115b of the funnel 115 to adjust the desired etch rate. In general, the shorter the distance Ds between the wafer 130 and the gas outlet 115b of the funnel 115, the faster the etching rate. According to one embodiment, the distance Ds between the wafer 130 and the gas outlet 115b of the funnel 115 is 5-15 mm.

According to the above-mentioned deep etching experiment, a 6-inch wafer was used for the test, and the deep trench of the deep trench to be etched was 27.5 (ditch diameter 6 μm, depth 165 μm), and the obtained data are shown in the following table. The comparative example in the table below uses the STS machine (Pegasus) listed in 2005 to form a deep trench. Contrary to this experimental example, the diameter D1 of the funnel outlet and the inner diameter D2 of the limiting ring are smaller than the diameter of the wafer. The distance Ds between the wafer and the funnel outlet can only be set to 0.5 mm.

As can be seen from the following table, according to the above, as long as the funnel outlet diameter D1 and the inner diameter D2 of the limiting ring are larger than the wafer diameter, the product yield is immediately increased, and the ratio of the etched area (Impact Area) is from the original 70% dropped to 5%.

^a is usually distributed in the peripheral area of the wafer, which refers to the area where the inclination angle of the trench is too large to meet the demand of the product.

^b In general, more than 15% of the bad areas represent products that cannot be shipped and accepted by customers.

^c trench depth maximum - minimum trench depth

^d calculation formula = (depth maximum - depth minimum) / (2 × depth average)

The angle of the center line of the ^e ditch from the vertical line

^f General MEMS products require <0.4 degrees, and high-precision products (such as gyroscopes) must be <0.2 degrees.

It is found that since the STS machine is designed such that the diameter of the funnel outlet and the inner diameter of the limiting ring are smaller than the diameter of the wafer, the etching plasma is concentrated in the central area of the wafer, thereby reducing the ability to laterally etch the sidewall of the trench. It achieves its high-speed deep etching to shorten the etching time. However, this method makes the plasma density distribution uneven, and the farther away from the central region, the greater the etching tilt angle, so that the peripheral edge region of the wafer becomes a large area of poor etching area, and finally the product in the peripheral edge of the wafer can be disposed of. To make the product yield greatly reduced. The finished product located between the center area of the wafer and the peripheral area, because the tilt angle of the deep trench is still too large, will cause noise, affect the transmission of signals, and does not conform to the customer's product specifications, and can only be reduced to general application products.

After careful adjustment, the diameter of the funnel outlet and the inner diameter of the limiting ring are larger than the diameter of the wafer. It is found that it is not necessary to change other etching parameters or add any other process, which not only greatly improves the yield but also maintains a certain etching rate. . In fact, if the energy of the etched plasma is not increased, the etch rate is only about 20% slower. However, the reduced etch rate can be compensated by increasing the energy of the etched plasma, with the actual result being the same etch rate. This effect is also directly reflected in the number of wafers cast per month. For example, in general MEMS products, the accelerator products and autofocus device products increase the number of wafer shots by 2.4 times and 6 times respectively. . In the case of high-end MEMS products, new customers of gyroscopes have been successfully introduced. Gyro is one of the most demanding applications in high-end MEMS products. All of these show that the products produced by the improved equipment can be highly recognized by customers.

It can be seen from the above embodiments of the present invention that the above embodiments of the present invention can not only produce an etched plasma having a relatively uniform density, but also increase the plasma distribution area, that is, the plasma can be substantially focused on a plane, thereby greatly improving. Yield of MEMS products.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . Etching reaction chamber

105. . . Air inlet

110. . . Coil

115. . . funnel

115a. . . Air inlet

115b. . . Air outlet

120. . . Limit ring

125. . . Carrying platform

130. . . Wafer

150. . . Plasma

D1. . . Funnel outlet diameter

D2. . . Limiting ring inner diameter

Ds. . . The distance between the wafer and the funnel outlet

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a schematic cross-sectional view showing an etching reaction chamber according to an embodiment of the present invention. The etching reaction chamber can be disposed in a deep etching machine.

100. . . Etching reaction chamber

105. . . Air inlet

110. . . Coil

115. . . funnel

115a. . . Air inlet

115b. . . Air outlet

120. . . Limit ring

125. . . Carrying platform

130. . . Wafer

150. . . Plasma

D1. . . Funnel outlet diameter

D2. . . Limiting ring inner diameter

Ds. . . The distance between the wafer and the funnel outlet

Claims (10)

A planar focusing deep etching plasma generating device, comprising: an etching reaction chamber comprising: a reaction chamber inlet; a coil disposed on an outer side of the reaction chamber wall and located in the reaction chamber Below the gas port; a funnel disposed in the reaction chamber and located below the coil, the diameter of the gas inlet of the funnel is larger than the diameter of the gas outlet of the funnel, and the diameter of the gas outlet of the funnel is larger than a wafer diameter and less than or equal to The diameter of the wafer is 1.2 times; and a limiting ring is disposed on the inner side wall of the funnel. The inner diameter of the limiting ring is less than or equal to 1.2 times the diameter of the wafer and greater than or equal to the diameter of the air outlet of the funnel. The device for generating a deep etching plasma according to claim 1, further comprising a carrying platform disposed under the funnel outlet for carrying the wafer. The apparatus for producing a deep etching plasma according to claim 1, wherein a distance between the wafer and the funnel outlet is 5-15 mm. The device for generating a deep etching plasma according to claim 1, wherein when the wafer is a 6-inch wafer, the diameter of the gas outlet of the funnel is 152.4-160 mm, and the inner diameter of the limiting ring is 160-180 mm. A device for producing a deep etching plasma according to claim 1, wherein When the wafer is 8 吋 wafer, the diameter of the gas outlet of the funnel is 203.2-205 mm, and the inner diameter of the limiting ring is 205-225 mm. An etching reaction chamber can be installed in an etching machine for generating a planar focusing deep etching plasma, the etching reaction chamber comprising: a reaction chamber inlet device for inputting an etching gas; and a coil disposed at The reaction chamber is below the air intake device for causing the etching gas to generate an etching plasma; a funnel is disposed under the coil to concentrate the etching plasma to a distribution range greater than a wafer diameter and less than or equal to the a 1.2-fold diameter of the wafer; and a confinement ring disposed within the funnel for filtering the etched plasma to reduce the number of ions moving laterally in the etched plasma, and the inner diameter of the confinement ring is less than or equal to The diameter of the wafer is 1.2 times and greater than or equal to the diameter of the gas outlet of the funnel. The etching reaction chamber of claim 6, further comprising a carrying device disposed under the funnel for carrying the wafer. The etching reaction chamber of claim 6, wherein the distance between the wafer and the funnel is 5-15 mm. The etching reaction chamber of claim 6, wherein the diameter of the gas outlet of the funnel is larger than the diameter of the wafer and less than or equal to 1.2 times the diameter of the wafer. An etching reaction chamber as claimed in claim 6, wherein the limiting ring The inner diameter is less than or equal to 1.2 times the diameter of the wafer and greater than or equal to the diameter of the gas outlet of the funnel.