Name: 斯坦福大學納米加工設備：幹法蝕刻 - 選擇幹法蝕刻工藝和工具（第 4 部分，共 4 部分） (Stanford Nanofabrication Facility: Dry Etching - Choosing a Dry Etching Process & Tool (Part 4 of 4))
Uploaded: 2025-06-07T15:44:37.000Z
Duration: 18 min 58 s

Hi, I'm Jim McVitie, and this is part four of a four-part series of lectures on dry etching.

大家好，我是吉姆-麥克維蒂（Jim McVitie），這是幹法蝕刻四部曲系列講座的第四部分。

In this lecture, I'm going to talk about choosing a dry etching process and tool.

在本講座中，我將講述如何選擇幹蝕刻工藝和工具。

Previously, I talked about, I gave an introduction to dry etching.

之前，我談到過，我給大家介紹過幹蝕刻法。

I've been followed by basic applied methods and types of dry etching tools, followed by dry etching mechanisms.

接下來，我介紹了幹蝕刻的基本應用方法和工具類型，然後是幹蝕刻機制。

In this lecture, I'm going to cover what are the issues that control etch process choice, etch chemistry choices, and I'll talk about the role of the use of boiling points to help determine useful etch products, and polymer crayoffs in oxide etching.

在本講座中，我將介紹控制蝕刻工藝選擇、蝕刻化學選擇的問題，並將討論使用沸點幫助確定有用蝕刻產品的作用，以及氧化物蝕刻中的聚合物裂解。

I'll then cover etch crayons in different materials, and end with a comparison between different etch configurations.

然後，我將介紹不同材料的蝕刻蠟筆，最後比較不同的蝕刻結構。

哪些問題控制著蝕刻工藝的選擇？

Here we show a diagram we showed previously of our photoresist over a film that was being etched over a substrate in the polysilicon etch case.

這裡展示的是我們之前展示過的一張圖，圖中顯示的是我們的光刻膠覆蓋在多晶硅蝕刻案例中正在基底上蝕刻的薄膜上。

What etch tools and process should we use to get desired etch characteristics for our structure?

我們應該使用什麼蝕刻工具和工藝來獲得結構所需的蝕刻特性？

So here's going through some of the issues.

下面我們就來談談其中的一些問題。

First is, are there volatile etch products?

首先，是否有揮發性蝕刻產品？

The etch depth controls selectivity means, what is the matte material, stopping material, allow losses.

蝕刻深度控制選擇性意味著什麼？

Deeper depths require higher rates and higher selectivities.

更深的深度需要更高的速率和更高的選擇性。

If we're talking about really deep, and we're talking about silicon, then we can use what we call the deep silicon etch process, with fluorine based, with a switching between etch and deposition.

如果我們談論的是真正的深度，而且是硅，那麼我們可以使用我們稱之為深度硅蝕刻工藝的氟基工藝，在蝕刻和沉積之間切換。

We have a control, we can set the temperature in the reactor, and then we also have wafer heating depending on the process conditions, how much power we have, and by power.

我們有一個控制裝置，可以設定反應器中的溫度，然後還可以根據工藝條件、功率大小和功率對晶片進行加熱。

Temperature affects the etch and depth rates.

It affects profile, selectivity, and it can affect resistive degradation.

它會影響輪廓和選擇性，還可能影響電阻衰減。

If the resistive gets too hard, it can degrade and be very difficult to remove, and actually affect the profile as we're going deeper.

如果電阻太硬，它就會變質，很難去除，而且實際上會影響我們的深度剖面。

And finally, in terms of etch temperature, many of our tools have backside helium used to improve the heat transfer between the wafer and the electrodes.

最後，在蝕刻溫度方面，我們的許多工具都使用背面氦氣來改善晶片和電極之間的熱傳導。

And finally, we have the issue of initial breakthroughs.

Some of the steps we will begin with a step that will just remove any oxide or polymer before we begin the process.

在某些步驟中，我們會先去除氧化物或聚合物，然後再開始加工。

This is very important when you have a very high selectivity process.

這一點在高選擇性工藝中非常重要。

You have to start with your material and oxide can slow you down.

你必須從你的材料開始，氧化物會拖慢你的速度。

So sometimes you go in and just remove that oxide and then switch to the high selectivity process.

是以，有時只需去除氧化物，然後轉用高選擇性工藝。

For etching we have, for the case of silicon and germanium, we use halogens, fluorine, chlorine, bromine, to form halides, volatile halides.

對於硅和鍺的蝕刻，我們使用鹵素、氟、氯、溴來形成鹵化物、揮發性鹵化物。

And the fluorine tends to be faster, but more isocropic than the fluorine and bromine.

而氟的速度往往更快，但比氟和溴的同向性更強。

For metals, we use the halogens also to form metal halides, which may or may not be volatile.

對於金屬，我們還使用鹵素形成金屬鹵化物，這些鹵化物可能會揮發，也可能不會揮發。

We may need boron trifluoride and a sputtering to remove an initial oxide.

我們可能需要三氟化硼和濺射來去除初始氧化物。

Boron trifluoride is a very interesting chemical in that it not only removes a lot of oxides, it also, when in the gas chemistry, it removes any water vapor or oxygen that may be coming from the surfaces or other places.

三氟化硼是一種非常有趣的化學物質，它不僅能去除大量氧化物，還能在氣體化學反應中去除可能來自表面或其他地方的水蒸氣或氧氣。

So it really, it generates an environmental void of any oxidizers.

是以，它確實能產生一種沒有任何氧化劑的環境。

Metal oxides and nitrites, we use halogens again, plus ion bombardment and maybe boron trifluoride.

金屬氧化物和亞硝酸鹽，我們再次使用鹵素，加上離子轟擊，也許還有三氟化硼。

For silicon oxide, we tend to use carbon fluorides, mixtures, plus maybe CHF3.

對於氧化硅，我們傾向於使用氟化碳、氟化碳混合物以及 CHF3。

The CF4 compound may have CHF3 added or not, or maybe hydrogen added.

CF4 化合物可以添加或不添加 CHF3，也可以添加氫。

Plus we'll add in additives that will enhance or reduce deposition.

此外，我們還會添加添加劑，以增強或減少沉積。

So oxygen and fluorine that tend to remove the polymer and therefore give it better control.

是以，氧和氟往往會去除聚合物，從而使其得到更好的控制。

For nitrite, we can either use an oxide etch or we use a fluorine-based etch where we add oxygen or nitrogen.

對於亞硝酸鹽，我們既可以使用氧化物蝕刻，也可以使用添加氧氣或氮氣的氟基蝕刻。

For polymer, we typically use oxygen, but we can add either argon or fluorine to help the process.

對於聚合物，我們通常使用氧氣，但也可以添加氬氣或氟氣來幫助處理。

Fluorine added, when you have a really tough polymer, sometimes a little bit of fluorine added to oxygen will break through a tough polymer that has a lot of cross-linking.

添加氟時，如果聚合物非常堅韌，有時在氧氣中添加一點氟，就能擊穿有大量交聯的堅韌聚合物。

And argon is used when we want to add more ion bombardment.

當我們想增加離子轟擊時，就會使用氬氣。

Inhibitory deposition, we use the fluorocarbons, CHF3, hydrogen, and sometimes both nitrogen or oxygen can help with inhibitory deposition.

抑制沉積，我們使用碳氟化合物、CHF3、氫氣，有時氮氣或氧氣也能幫助抑制沉積。

And this is for controlling sidewalls and anisotropic etching.

這是為了控制側壁和各向異性蝕刻。

When we have marginal byproduct volatility, we often increase the temperature and also increase ion bombardment.

當副產品的揮發性很小時，我們通常會提高溫度，同時增加離子轟擊。

The downside is that the increased temperature and ion bombardment can damage the photoresist and lower selectivity.

缺點是溫度升高和離子轟擊會損壞光刻膠，降低選擇性。

This slide, I'm going to talk about the use of boiling points to evaluate possible byproducts.

在這張幻燈片中，我將講述如何利用沸點來評估可能的副產品。

So what I have here is a table of different elements, and I have chloride products, fluoride products, and their boiling points.

是以，我這裡有一張不同元素的表格，有氯化物產物、氟化物產物和它們的沸點。

And the reason we look at boiling points is boiling points are often easily available, whereas from possible products, we often do not have the data for vapor pressures at the temperature we're doing the etching is not available.

我們查看沸點的原因是，沸點往往很容易獲得，而對於可能的產品，我們往往沒有在蝕刻溫度下的蒸氣壓數據。

But we can extrapolate roughly what the vapor pressure is at the operating temperature from boiling points.

但我們可以根據沸點推斷出工作溫度下的蒸汽壓力大致是多少。

What I have here is a plot of temperature versus vapor pressure for the case of gallium tichochloride.

我這裡有一張溫度與蒸氣壓的關係圖，顯示的是二氯化鎵的情況。

And we see here at the top here, here's the atmospheric pressure.

我們在頂部看到的是大氣壓力。

We have the boiling point at about 200 degrees C.

Now down here at 50 degrees C, what might be a typical etching temperature, we see the vapor pressure is on the order of one millitor.

在 50 攝氏度的典型蝕刻溫度下，我們可以看到蒸氣壓約為 1 毫託。

And millitor, one to ten millitor is what we like to have for the byproduct so that they come off the surface.

我們希望副產品的濃度在一到十毫克之間，這樣它們就能從表面浮出。

So we see here there's a relationship between boiling point and vapor pressure at the operating temperature.

是以，我們可以看到，在工作溫度下，沸點和蒸汽壓力之間存在一定的關係。

So we can use boiling point to help us determine possible byproducts.

是以，我們可以利用沸點來幫助我們確定可能的副產品。

And so typically, we're interested in boiling point less than 200 degrees for vapor that we're going to be operating near room temperature or less than 300 degrees for vapor that might be heated.

是以，通常情況下，我們對沸點小於 200 度的蒸汽感興趣，因為我們將在接近室溫的溫度下操作，或者對可能被加熱的蒸汽感興趣，因為它的沸點小於 300 度。

So aluminum chloride has a boiling point that actually sublimes at 180 degrees C.

是以，氯化鋁的沸點實際上是 180 攝氏度。

Whereas aluminum fluoride has a boiling point of 1,200 degrees or 1,300 degrees.

而氟化鋁的沸點為 1200 度或 1300 度。

So we see obviously if we're going to etch aluminum, we want to use chlorine.

是以，如果我們要蝕刻鋁，顯然要使用氯氣。

When we take a look at copper, we see copper chloride has a boiling point of 1,500 degrees C.

我們看一下銅，就會發現氯化銅的沸點為 1 500 攝氏度。

So basically, we're not going to etch very well copper, either chlorine or fluorine.

是以，基本上，無論是氯還是氟，我們都無法很好地蝕刻銅。

Whereas silicon tetrafluoride has a boiling point of minus 86 degrees.

而四氟化硅的沸點為零下 86 度。

So it means that fluorine is going to come off easier.

So we're probably going to have a higher equity than we know.

是以，我們的資產淨值可能會比我們知道的要高。

But we can easily etch this temperature, a boiling point of 60 degrees C for silicon tetrafluoride is well within the range that we can easily do etching.

但我們可以在這個溫度下輕鬆進行蝕刻，四氟化硅的沸點為 60 攝氏度，完全在我們可以輕鬆進行蝕刻的範圍內。

And as we've shown throughout the lectures, that chlorine does a very good job at etching silicon.

正如我們在整個講座中所展示的，氯在蝕刻硅方面的效果非常好。

So here I show a polymer payoff for oxide etching.

是以，我在這裡展示了氧化物蝕刻的聚合物回報。

What I have here, I'm showing basically pressure on one side.

我這裡顯示的基本上是一側的壓力。

I'm showing basically very low pressure to a high pressure one torr.

我顯示的基本上是非常低的壓力到 1 託的高壓。

And typically, we're going to get much at the high pressure.

通常情況下，我們會在高壓下得到很多東西。

We can have low ion energy because of all the collisions.

由於所有的碰撞，我們可以獲得較低的離子能量。

At low pressure, we're going to have high ion energy.

在低壓條件下，離子能量會很高。

In the x-axis here, I'm showing basically the fluorocarbon composition.

在 x 軸上，我顯示的基本上是碳氟化合物的成分。

So that as one side, I'm adding oxygen and fluorine.

這樣，我在一邊加入氧氣和氟。

And so in this case, I'm going to have a lot more free fluorine going on.

是以，在這種情況下，我會有更多的遊離氟。

But at high pressures, with the high fluorine case, we can actually get isocropic etching of oxide.

但在高壓和高氟的情況下，我們實際上可以獲得氧化物的各向同性蝕刻。

At low pressures, rather than adding oxygen, we typically go for maybe hydrogen or adding carbon.

在低壓條件下，我們通常不會加入氧氣，而是加入氫氣或碳。

We go more toward the polymer deposition range.

我們更傾向於聚合物沉積範圍。

Before we get to actual deposition of polymer, we get the most anisotropic etching.

在實際沉積聚合物之前，我們要進行最各向異性的蝕刻。

If we go more towards the deposition threshold, we actually start getting wall slope and the etch rate drops down.

如果我們更接近沉積閾值，實際上就會開始出現壁斜，蝕刻率也會下降。

And we see that at high pressures, we get polymer deposition that occurs much earlier than at low pressures.

我們發現，在高壓條件下，聚合物沉積的時間比低壓條件下早得多。

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斯坦福大學納米加工設備：幹法蝕刻 - 選擇幹法蝕刻工藝和工具（第 4 部分，共 4 部分） (Stanford Nanofabrication Facility: Dry Etching - Choosing a Dry Etching Process & Tool (Part 4 of 4))

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