等离子体干法去胶机工艺原理及使用Application of plasma dry Resist Asher

等离子体干法去胶机工艺原理及使用

1) 等离子去胶反应机理：

   在干法等离子去胶技术中，氧是首要腐蚀气体。它在真空等离子去胶机反响室中受高频及微波能量效果，电离发生氧离子、游离态氧原子 O*、氧分子和电子等混合的等离子体，其间具有强氧化才能的游离态氧原子 （约占 10-20%）在高频电压效果下与光刻胶膜反响： O2→O*+ O*， CxHy + O*→CO2↑+ H2O↑。反应后生成的 CO2 和 H2O，随即被抽走。

2) 等离子去胶操作方法：

   将待去胶片插入石英舟并平行气流方向，推入真空室两电极间，抽真空到 1.3Pa，通入恰当氧气，坚持反响室压力在 1.3-13Pa，加高频功率，在电极间发生淡紫色辉光放电，经过调理功率、流量等技术参数，可得不一样去胶速率，当胶膜去净时，辉光不见。

3）等离子去胶影响要素：

   频率挑选：频率越高，氧越易电离构成等离子体。频率太高，以致电子振幅比其平均自由程还短，则电子与气体分子磕碰概率反而减少，使电离率降低。通常常用频率为 13.56MHz及2.45GHZ 。

   功率影响：关于必定量的气体，功率大，等离子体中的的活性粒子密度也大，去胶速度也快；但当功率增大到必定值，反响所能耗费的活性离子到达饱满，功率再大，去胶速度则无显着添加。由于功率大，基片温度高，所以应根据技术需求调理功率。

   真空度的挑选：恰当进步真空度，可使电子运动的平均自由程变大，因而从电场取得的能量就大，有利电离。别的当氧气流量必守时，真空度越高，则氧的相对份额就大，发生的活性粒子浓度也就大。但若真空度过高，活性粒子浓度反而会减小。

氧气流量的影响：氧气流量大，活性粒子密度大，去胶速率加速；但流量太大，则离子的复合概率增大，电子运动的平均自由程缩短，电离强度反而降低。若反响室压力不变，流量增大，则被抽出的气体量也添加，其间尚没参与反响的活性粒子抽出量也随之添加， 因而流量添加对去胶速率的影响也就不甚显着。

Principle and application of plasma dry Resist Asher

1) reaction mechanism of plasma degumming: oxygen is the primary corrosive gas in dry plasma degumming technology.

     It receives high frequency and microwave energy effect in the reaction chamber of vacuum plasma degummer, ionizes and produces a plasma mixed with oxygen ion, free oxygen atom o *, oxygen molecule and electron, among which the free oxygen atom with strong oxidation ability (about 10-20%) reacts with photoresist film under high frequency voltage effect: O2 → o * + O *, CxHy + O * → CO2 ↑ + H2O ↑. After reaction, CO2 and H2O are extracted.

2) Operation method of Resist Asher: 

     Insert the film to be removed into the quartz boat and parallel to the air flow direction, push it into the space between the two electrodes of the vacuum chamber, vacuumize to 1.3pa, inject appropriate oxygen, and keep the pressure of the reaction chamber at 1.3-13pa, add high-frequency power, generate lavender glow discharge between electrodes. After adjusting technical parameters such as power, flow, etc., different degumming rate can be obtained. When the film is degummed, the glow is not seen. 

3) Factors affecting plasma Resist Asher: frequency selection: 

    The higher the frequency is, the easier oxygen is ionized to form plasma. If the frequency is too high, the amplitude of the electron is shorter than its average free path, the probability of collision between the electron and the gas molecule will be reduced, and the ionization rate will be reduced. The commonly used frequencies are 13.56MHz and 2.45GHz. Power effect: for a certain amount of gas, the power is high, the density of the active particles in the plasma is high, and the degumming speed is fast; however, when the power is increased to a certain value, the active ions consumed by the reaction are full, and the degumming speed is not significantly increased with the power. Because of the high power and substrate temperature, the power should be adjusted according to the technical requirements. Selection of vacuum degree: if the vacuum degree is improved properly, the average free path of electron motion will be enlarged, so the energy obtained from the electric field will be larger, which is favorable for ionization. In addition, when the oxygen flow must be constant, the higher the vacuum degree is, the larger the relative share of oxygen will be and the concentration of active particles will be. However, if the vacuum is too high, the concentration of active particles will decrease. The influence of oxygen flow rate: large oxygen flow rate, high density of active particles, accelerated degumming rate; but too large flow rate, the ion recombination probability increases, the average free path of electron motion shortens, and the ionization intensity decreases. If the pressure of the reaction chamber is constant and the flow rate increases, the amount of gas pumped out will be added, and the amount of active particles that have not participated in the reaction will also be added, so the effect of flow rate addition on the degumming rate is not significant.