WO2014200328A1 - A method for forming silicon grass - Google Patents

Abstract

The present invention relates to a method for forming Si grass structure comprising: forming a silicon well (100); and etching the silicon well to form silicon grass structure (200); characterized in that the step of forming silicon well (100) is conducted using a standard deep reactive ion etching Bosch process using photoresist as the masking material. The present invention provides more surface area of the sensing membrane thus increasing the performance of a sensor.

Description

Description

Title of Invention: A METHOD FOE FORMING SILICON GRASS

[ 1 ] FIELD OF INVENTION

f 2] The present invention relates to a method for forming a silicon grass structure which its application is in sensor technology,

1_.31 BACKGROUND OF THE INVENTION

(41 One of the most important feature in a sensor is a sensing membrane. Currently, the ensing membran is fabricated in a form of fiat surface. The flat surface structure of a sensing membrane is limiting the reactivity of tons that would cause no enough surface potential for the sensor device to property function. This would affect, the performance of the sensor. While many had invented a method for forming a silicon sensing membrane such as inUS 20!0/lK}92888. which construes : process for etching a silicon-containing substrate to form structures is provided, in the process, a metal is deposited and patterned onto a silicon-containing substrate (commonly one with a resistivity above 1-10 ohm-em) in such a way that the metal is present and touches silicon where etching is desired and is blocked from touching silicon or not present elsewhere. The metallized substrate is submerged into an etchant aqueous solution comprising about 4 to about 49 weight percent HP and an oxidizing agent such as about 0,5 to about 30 weight percent H.sub,20.sub.2, thus producing a metallized substrate with one or more trenches. A second silicon etch is optionally employed t remove nanowires inside the one or more trenches.

[5 J However, the prior art still could not solve the above problem which isrelaied to low sttrface-area- o-volnme ratio of the sensing material structure,

[6] Therefore it is a need for an invention thai can overcome the above mentioned

problem.

[7] SUMMARY OF THE INVENTION

[8] According to an aspect of the present invention, the present invention pro- videsmethod for forming Si grass structure comprising;formtng a silicon well ( 100); etching the silicon well to form silicon grass structure (200); characterised in that the step of forming silicon well { 100) is conducted using a standard deep reactive ion etching Bosch process using photoresist as the masking material. The above provision is advantageous as the present invention provides more surface area of the sensing material, thus increasing the performance of the sensor. The method tor forming the silicon, grass structure is invented using inductivel coupled plasma (ICP) deep reactive ion etching (DRIE) process chamber, it was found that the diameter and height of silicon grass re controllable by varying the wafer chuck silicon temperature process parameter. Bosch process is one type of silicon etching technology for high-aspect

Claims

flow rate of 8 to 10 seem; wherein the silicon s at 0°C below pressure of 4 to 5 Pa for a predetermined time.

(Claim 8] A method for forming S grass structure as claimed in Claim 5. wherein the third sequential etching and passi ation (205) further comprising: exposing the silicon to SP_ft plasma for one seconds at flow rate of 200 to 250secni;

exposing the silicon to a mixture of CJP* and 0_:> plasma for three seconds, with the€₄F_¾ at. a flow rate of 120 to 150 seem and the 0_; at a flow rate of 8 to 10 seem; whereto the silicon at -4 to -5 ^'C below pressure of 4 to 5 Fa for a predetermined time.